Spectroscopy Beauchamp 1

Basics of Mass Spectroscopy

The roots of mass spectroscopy (MS) trace back to the early part of the 20th century. In 1911 J.J. Thomson used a primitive form of MS to prove the existence of isotopes with neon-20 and neon- 22. Current, easy-to-use, table-top instruments of today are a very recent luxury. In less than a day, you could be running samples on a mass spectrometer. However, it would take you longer to learn the many intricacies of MS, something we cannot pursue in a book such as this. We will mainly look at electron impact mass spectrometry (EI) and briefly mention chemical ionization (CI) as they pertain to determining an organic structure. The technique of MS only requires very small amounts of sample (g-ng) for high quality data. For that reason, it is the preferred method to evaluate product structures in combinatorial chemistry, forensic laboratories and with complicated biological samples. Generally, in these situations, you have some indication of the structure(s) possible. MS can be coupled to separation techniques such as gas chromatography (GC) and high pressure liquid chromatography (HPLC) to make a combination technique (GC-MS and LC-MS). GC can separate components in relatively volatile mixtures and HPLC can separate components in relatively less volatile mixtures. There are also options for direct inlet of solid samples and sampling methods for high molecular weight biomolecules and polymers. But, these are beyond the scope of this book. MS is different from the other spectroscopies (UV-Vis, IR, NMR) in that absorption or emission of electromagnetic radiation is not used. Rather, the sample (molecule) is ionized by some method (often a high energy electron beam = electron impact = EI). An electron is knocked out of a bonding molecular orbital (MO), forming a radical cation. Dications and anions can also be formed, but we will not consider these possibilities.

high EI mass spec RH+ energy RH 2 e- e- + radical cation

The cations formed are accelerated in a high voltage field, focused and separated by mass to charge ratio (m/z or m/e) using a magnetic and/or electric fields. A detector indicates the intensity of each mass signal and the mass data (x axis) are plotted against this intensity (y axis) to produce a spectrum similar to that shown below. It is also possible that this same data can be printed in a tabulated, numerical form (shown in the side box). The most useful information from the MS is the molecular weight (the M+ peak), which can indicate what the formula is. The formula provides the degree of unsaturation, which gives important clues to the possible structures (rings and pi bonds). Fragment peaks that are detected provide hints as to the nature of the carbon skeleton, heteroatoms and functional groups present. The most abundant peak (largest) in the mass spectrum is called the base peak. It is assigned a value of 100% and all other detectable masses are indicated as a percent of the base peak. The molecular weight peak is called the mass peak or molecular ion peak or parent peak and symbolized with an M. Since this peak is a radical cation, it often also has a + or + . (plus sign and a dot) superscript as well. We will use M+. There is often ambiguity in the other fragment peaks because of high energy rearrangements that are possible. It is usually very difficult to assign a structure to a completely unknown molecule based solely on mass spectroscopy. But a mass spectrum can help provide a very important piece of the puzzle, the molecular weight.

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base peak = largest peak in MS spectrum = 100% peak, other peaks are reported as a percent of this peak

molecular ion = M = M+ = M+ = parent peak Only specific isotopic masses are found in the molecular formula. We do not see “average” masses that are listed in the periodic table. Also present will be M+1, M+2, etc. peaks due to other isotopes. On low resolution MS these peaks can help decide what the molecular formula is.

In the MS example below, some of the peaks are very ‘logical’ (57, 85 and 91 are logical) and some are less so (39, 41, 42, 51 and 55). It is also true that peaks that are ‘logical’ are sometimes small or completely missing (119). Many of the other peaks will be explainable with certain assumptions about fragmentations discussed later in this chapter. .

Tabulated Data 91 57 85 119 Mass percent O 1-phenyl-2-hexanone 27 6 C12H16O , MW = 176 28 2 29 24 57 85 = base peak 39 7 100 41 26 Many smaller 42 1 peaks are not 43 1 shown, but listed 50 1 in data table to 51 3 75 the left. 55 3 57 99 58 5 percent 60 1 relative 50 63 3 intensity 65 11 91 77 2 85 100 (base) 29 41 86 6 25 M+ 89 2 65 peak 90 2 27 176 91 36 39 58 86 92 92 6 0 176 7 = M+ 177 1 0 25 50 75 100 125 150 175 200 mass m = charge e

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Typical MS Instrument Features.

The moving charged cations (R-H+) can be made to curve in their direction of flight in a magnetic or electric field. The amount of curvature is determined by the mass (m) of the ions as shown in the following equations (assuming the charge, e, is constant = +1). The magnetic field (B) and/or accelerator plate voltage (V) can be altered to cause each possible mass to impact the detector. The charged masses must survive about 10-6 to 10-5 seconds to make this journey to the detector. Often there is some rational feature to explain each peak’s special stability that allows it to last long enough to reach the detector, where it becomes part of the data we examine. We will look at some of these features later in this discussion. We will not discuss other possibilities, such as metastable ions or +2 and negatively charged ions. Our main goal in this book is interpretation.

2 2 m = B r m = mass e 2V e = charge (usually +1) B = size of magnetic field r = radius of curvature V = voltage on accelerator plate r mV 1 = e B 

Besides just seeing a positively charged mass at the detector, we must resolve it from nearby mass values. MS instruments can be either low resolution (LRMS) or high resolution (HRMS). Low resolution MS instruments can generally resolve single amu values as high as about 2000 amu’s (e.g. they can distinguish 300 amu from 301 amu). An atomic mass unit is defined as 1/12 the mass of a neutral carbon-12 atom (12C = 12.0000, by definition). High resolution MS instruments can resolve masses as close as the fourth decimal place (XXX.XXXX). With such accuracy, an exact molecular formula can be determined by a computer. A molecular formula can also be obtained from LRMS, y:\files\classes\Spectroscopy Book home\1 Spectroscopy Workbook, latest MS full chapter.doc Spectroscopy Beauchamp 4

through a slightly more involved procedure. HRMS instruments tend to be more expensive and less common.

Exact Masses

We need to be precise in our calculation of possible masses for each collection of atoms because the atoms in any cation hitting the detector are specific isotopes. The atomic weights listed in the periodic table are average weights based on the abundance and mass of all of the naturally occurring isotopes of each element. For example, the atomic weight of bromine in the periodic table is 79.9, even though there is no bromine isotope with a mass of 80. The 79.9 atomic weight is a result of an approximate 50/50 mixture of two stable isotopes of mass 78.9 and 80.9. Because of this complication, we will require data on the exact masses and the relative abundance of the common isotopes that we expect to encounter. Those most useful to us in organic chemistry and biochemistry are listed below.

Average Element Atomic Weight Nuclides Exact Mass Relative Abundance* hydrogen 1.00797 1H 1.00783 100.0 2H (D) 2.01410 0.015

carbon 12.01115 12C 12.00000 100.0 13C 13.00336 1.11

nitrogen 14.0067 14N 14.00307 100.0 15N 15.00011 0.37

oxygen 15.9994 16O 15.9949 100.0 17O 16.9991 0.04 18O 17.9992 0.20

fluorine 18.9984 19F 18.9984 100.0

silicon 28.086 28Si 27.9769 100.0 29Si 28.9765 5.06 30Si 29.9738 3.36

phosphorous 30.974 31P 30.9738 100.0

sulfur 32.064 32S 31.9721 100.0 33S 32.9715 0.79 34S 33.9679 4.43

chlorine 35,453 35Cl 34.9689 100.0 37Cl 36.9659 31.98

bromine 79.909 79Br 78.9183 100.0 81Br 80.9163 97.3

iodine 126.904 127I 126.9045 100.0 *The most abundant nuclide is assigned 100% and the others assigned a fractional percent of that value. Coincidently, in the examples listed in the table above with more than one isotope, the lowest mass isotope is the 100% isotope. Spectroscopy Beauchamp 5

Obtaining a molecular formula from a HRMS is relatively straight forward Each possible molecular mass is unique when calculated to 3-4 decimal places and computers can do the calculations for us. Try the problems below. Unfortunately, here you have to do the calculations yourself.

Problem 1 - A low-resolution mass spectrum of 1,10-phenanthroline showed the molecular weight to be 180. This molecular weight is correct for the molecular formulas C14H12, C13H8O and C12H8N2. A high-resolution mass spectrum provided a molecular weight of 180.0688. Which of the possible molecular formulas is the correct one? What is the degree of unsaturation in 1,10-phenanthroline?

Problem 2 – Isopalhinine A, a natural product was found by low-resolution mass spectrometry to have a molecular weight of 291. Possible molecular formulas include C15H17NO5, C16H21NNO4, and C17H25NO3. High-resolution mass spectrometry indicated that the precise molecular weight was 291.1472. What is the correct molecular formula of isopalhinine? What is the degree of unsaturation?

To obtain a molecular formula from a LRMS requires more sophistication. Various possible formulas can be generated using the molecular ion peak and the rule of 13. The first possible formula assumes that only carbon and hydrogen are present. The molecular mass (M+) is divided by 13 generating an integer (n) and a remainder (r). The number 13 represents the mass of one carbon atom and one hydrogen atom. The CH formula becomes CnHn+r. All molecular hydrocarbons have even mass molecular weights.

Each of these masses = 13 amu = C + H H H H H H H (We assume there are "n" of them if the unknown was a hydrocarbon. H C C C C C C H This is our starting point formula.)

H H H H H H These are left over hydrogen atoms = r

M M = molecular weight = n + r 13 n = number of CH units = quotient r = left over hydrogens = remainder Possible hydrocarbon molecular formula = C H (as a hydrocarbon always an even mass) n n+r

The degree of unsaturation can be calculated for this formula and possible rings and/or pi bonds can be considered (discussed in the introduction, p 10). If oxygen and/or nitrogen (and other elements) are present, the C/H numbers in the molecular formula must be changed by an amount equal to the new element’s isotopic mass. It is assumed, when substituting atoms, that the major isotope is used in all cases (always the lowest mass isotope, for us), H=1, C=12, N=14, O=16, S=32, Cl=35, Br=79. Since oxygen weighs 16, we can subtract CH4 (= 16) from the formula and substitute in the oxygen atom. If two oxygen atoms were present, we would subtract 2x(CH4) = C2H8 and so forth. Nitrogen-14 would substitute for CH2 and n nitrogen atoms would substitute for (CH2)x(n). If we did not have enough hydrogen atoms for some reason (it happens), we could take away one carbon atom and add in 12 hydrogen atoms, or if there were too many hydrogens, you could do it the other way around and add one carbon and take away 12 hydrogen atoms. Information concerning the possible number of nitrogen atoms in the molecular formula is also available in the molecular mass. If the molecular mass is an even number, then the number of y:\files\classes\Spectroscopy Book home\1 Spectroscopy Workbook, latest MS full chapter.doc Spectroscopy Beauchamp 6

nitrogen atoms has to be zero or an even number (= 0, 2, 4...... ). If the molecular mass is an odd number, then the number of nitrogen atoms has to be odd (= 1, 3, 5.....). Remember, each nitrogen atom in the formula adds an extra bonding position.

C C C C O C C C C N N C C C C N

C H N CnH2n+2Ox CnH2n+3N1 n 2n+4 2 (N is odd) (N is even) C = even mass C = even mass C = even mass H = even mass H = odd mass H = even mass O = even mass O = even mass O = even mass MW = even mass MW = odd mass MW = even mass

Problem 3 - An unknown compound produces a molecular weight of 108. What are all possible formulas having only carbon and hydrogen or having carbon, hydrogen and an oxygen atom (…two oxygen atoms) or having carbon hydrogen and nitrogen (what is the minimum of nitrogen atoms that would have to be present)? What is the degree of unsaturation for each of these possibilities? Is it possible that the formula has only a single nitrogen? If so what would the formula be? If not, why not? What if the molecular weight was 107? (Same questions.)

To choose among the various formulas generated from the rule of 13, we can consider the other possible isotopes present and their relative abundances to calculate the size of the peaks just one mass unit (M+1) and two mass units (M+2) larger than the molecular ion peak (M+). For each possible formula, percents of the M+1 and M+2 peaks versus the M+ peak are calculated. In this calculation the M+ peak is assumed to be 100% for comparisons with M+1 and M+2, regardless of the base peak. These calculated values are compared to the experimental values to determine the most likely formula. The reason for this is that the relative sizes of the M+1 and M+2 peaks are determined by the number and isotopic abundance of the elements present. The presence of either chlorine, bromine or sulfur significantly changes the M+2 peak. If there are multiple halogens (Cl and Br), the M+2, M+4, M+6 and beyond can be calculated and compared to the experimental mass spectrum. This approach only works if the M+ peak is large enough so that M+1 and M+2 are significant. If the M+ peak is too small, we can’t tell what the relative fractions of M+1 and M+2 are. Let’s take a look at how one could calculate the relative size of these peaks (M+1 and M+2).

Sample calculation using M+, M+1, M+2 peaks to identify the molecular formula by LRMS

We will assume an actual formula that is C4H10O. However, we will pretend we don’t know this. How could the M+1 and M+2 lead us to the correct formula? The molecular mass of C4H10O is 74 and that would produce our molecular ion peak, M+. We would have an extra amu in the mass if we had a different isotope one amu higher. We could do this 4 ways with carbon (because there are four 13C atoms) 10 ways with hydrogen (2H = D) and 1 way with oxygen (17O). The probabilities for these possibilities are shown below for the M+1 peak. If we add all of these together we can see the total probability for getting an M+1 peak relative to 1.0000 for getting the M+ peak. Using a similar strategy we can estimate the probability for getting an M+2 peak, which will be considerably lower since we have to get two 13C or two 2H or one 13C and one 2H. The main contribution to the M+2 peak is the 18O isotope. Taken together, these three peaks would predict the indicated distribution for M+, M+1 and M+2 for this collection of atoms (C4H10O).

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molecular ion peak = M+ = 4x(12C) + 10x(1H) + 1x(16O) = 74 amu Whatever the size of this peak, as a fraction = 1.000 it is assumed to be 100% for as a percent = 100% comparison with the M+1 and M+2 peaks. M+1 peak - arises from different possibilities of one additional amu = 75 amu

1.11 13C one 13C = (4 ways) = 0.0439 101.11 12C + 13C 0.015 2D one 2H = (10 ways) = 0.0015 100.015 1H + 2D 17O 16 0.04 one O = 101.24 (1 ways) = 0.0004 16O + 17O+ 18O

sum of possibilities = (0.0439) + (0.0015) + (0.0004) = 0.0458

M+1 peak as a percent of M+ peak = (0.0458)x(100%) = 4.58%

M+2 peak - arises from different possibilities of two additional amu = 76 amu "mini" probability theory 1.11 2 two 13C = 4 x 3 2 There are 4 ways of picking 101.11 2 x 1 = (0.0439) (6 ways) = 0.0007 the first carbon and 3 ways of picking the second carbon 0.015 2 10 x 9 two 2H = (=4x3) and since all carbon 100.015 2 x 1 = (2.25x10-8)(45 ways) is the same, we can't tell what -6 carbon was picked first and = 1 x 10 = 0.000001 = too small to consider second, so we divide by two facorial (2x1). 18 0.20 one O = 101.24 (1 ways) = 0.0020 100% 0.015 13 2 1.11 (10 ways) one C and one H = 101.11 (4 ways) x 100.015 = 1 x 10-6 = 0.000065 = 0.0001

4.58% sum of possibilities = (0.0007) + (0.0020) + (0.0001) = 0.0028 0.28% M+2 peak as a percent of M+ peak = (0.0028)x(100%) = 0.28% M+ M+1 M+2 To find a possible molecular formula using the M+1 and M+2 peaks, we first find the correct molecular weight for our molecule (in this case mass = 74). Then we look through the M+1 and M+2 values for two values that match our mass spec data. In this case we see that C4H10O is a very close match and it becomes our best guess. M+ = molecular ion peak Exact Mass (M+1) (M+2) M+ = molecular ion peak Exact Mass (M+1) (M+2) (formulas) (formulas) 74 75 CH2H2O2 74.0117 1.95 0.41 CH2H2O2 74.9956 1.60 0.61 CH4N3O 74.0355 2.33 0.22 CH4N3O 75.0320 2.70 0.43 CH6N4 74.0594 2.70 0.03 CH6N4 75.0798 3.45 0.05 C2H2O3 74.0004 2.31 0.62 C2H2O3 75.0684 3.81 0.25 C2H4NO2 74.0242 2.69 0.42 C H NO 74.0480 3.06 0.23 Data tables exist with many values 2 6 etc. C3H6O2 74.0368 3.42 0.44 already calculated for comparisons. C3H10N2 74.0845 4.17 0.07 C4H10O 74.0003 4.52 0.28 Here is our compound. Since the molecular weight is even, the number of nitrogens atoms must be even (0,2,4...). Any formulas with an odd number of nitrogen atoms must be part of a fragment.

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Problem 4 – a. Calculate the relative intensities (as a percent) of M+, M+1 and M+2 for propene (CH3-CH=CH2) and diazomethane (CH2=N=N). Can these two formulas (C3H6 vs CH2N2) be distinguished on the basis of their M+1 and M+2 peaks? Calculate the exact mass (four decimal places) for both of these formulas. Can they be distinguished on the basis of exact mass? Helpful data are on page 4.

+ + + b. Both CHO and C2H5 have fragment masses of approximately 29, yet CHO has a M+1 peak of + 1.13% and M+2 peak of 0.20%, whereas C2H5 has a M+1 peak of 2.24% and M+2 peak of + + 0.01%. High resolution mass spec shows CHO to have a different fragment mass than C2H5 . Explain these observations and show all of your work. Helpful data are on page 4.

Chlorine, bromine and sulfur, when present, have very characteristic M+2 peaks (32.6% for Cl, 96.9% for Br and 4.4% for S). If multiple Cl’s and/or Br’s are present M+2, M+4 and beyond are indicative of the number and type of halogen(s) present. The various patterns are available in many references. However, you can calculate these values yourself, as was done above for the M+1 and M+2 peaks above.

one Cl – comparison of M+ peak (35Cl) to M+2 peak (37Cl)

M+ peak relative size 100% probability of 35Cl = 100 (1 way) = 0.758 100 + 32 (assigned a referenced value of 100%) 32% M+2 peak relative size probability of 37Cl = 32 (1 way) = 0.242 100 + 32

percent of M+ peak = 0.242 (100%) = 32% 0.758 M+ M+1 M+2

one Br – comparison of M+ peak (79Br) to M+2 peak (81Br)

M+ peak relative size 100% 97% probability of 79Br = 100 (1 way) = 0.508 100 + 97 (assigned a referenced value of 100%) M+2 peak relative size probability of 81Br = 97 (1 way) = 0.492 100 + 97 0.492 percent of M+ peak = (100%) = 97% M+ M+1 M+2 0.508

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one S – comparison of M+ peak to M+1 to M+2 peak

M+ peak relative size 32 100 probability of S = (1 way) = 0.950 100 + 0.79 + 4.43 100% (assigned a referenced value of 100%) M+1 peak relative size probability of 33S = 0.79 100 + 0.79 + 4.43 (1 way) = 0.008

percent of M+ peak = 0.008 (100%) = 0.8% 4.4% 0.950 0.8% M+2 peak relative size M+ M+1 M+2 probability of 34S = 4.43 100 + 0.79 + 4.43 (1 way) = 0.042

percent of M+ peak = 0.042 (100%) = 4.4% 0.950

one Br and one Cl – comparison of M+ peak to M+2 and M+4 peaks

M+ peak relative size probability of 79Br = 0.508 (from above) probability of 35Cl = 0.758 (from above) (probability of 79Br)(probability of 35Cl) = (0.508) (0.758)(1 way) = 0.385 129% (assigned a referenced value of 100%) M+2 peak relative size 100% probability of 81Br = 0.492 (from above) probability of 37Cl = 0.242 (from above) (probability of 79Br)(probability of 37Cl)(1 way) = (0.508) (0.242)(1) = 0.123 (probability of 81Br)(probability of 35Cl)(1 way) = (0.492) (0.758)(1) = 0.373 total = 0.496 31% percent of M+ peak = (0.496/0.373)x100% = 129% M+4 peak relative size (probability of 81Br)(probability of 37Cl)(1 way) = (0.492) (0.242)(1) = 0.119 M+ M+2 M+4 percent of M+ peak = (0.119/0.373)x100% = 31%

two Cl – comparison of M+ peak to M+2 peak to M+4 peaks

M+ peak relative size probability of two 35Cl = (0.758)2 (1 way) = 0.602 100% (assigned a referenced value of 100%) M+2 peak relative size 61% probability of 37Cl = 0.242 (from above) (probability of 35Cl)(probability of 37Cl)(2 ways) = (0.758) (0.242)(2) = 0.367 percent of M+ peak = (0.367/0.602)x100% = 61% 10% M+4 peak relative size (probability of 37Cl)(probability of 37Cl)(1 way) = (0.242)2(1) = 0.059 percent of M+ peak = (0.059/0.602)x100% = 10% M+ M+2 M+4

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Problem 5 - Calculate the relative intensities (as a percent) of M+, M+2 and M+4 for Br2. Use the probabilities from above.

+ Problem 6 - Calculate the relative intensities (as a percent) of M , M+2, M+4 and M+6 for BrCl2 and Br2Cl. Hint: All of the data you need to perform these calculations are in the examples above. Use the probabilities from above.

Energetics of Fragmentation of simple hydrocarbon patterns

Bonds are broken in fragmentations, forming radicals and/or cations. The energy costs for radicals and cations of common hydrocarbon patterns are worked out in the tables that follow. We first assume a C-H bond is homolytically broken (each atom gets one electron, no charge is formed). Next, we take away the cost of making the hydrogen atom (the same for every C-H bond) to find out what the cost is for forming only the carbon free radical. Lower energy possibilities are favored over higher energy possibilities. A few problems are provided just below the following tables to illustrate these points.

A similar diagram is constructed to estimate the energy costs of forming carbocations. We start out the same, but in this diagram we include the ionization potential of the carbon free radical, a value that can be measured experimentally. We again take away the energy to make the hydrogen free radical and also take away the energy change when the hydrogen atom attracts the extra electron (electron affinity) to become a hydride. What remains is an estimate of the energy to make only the carbocation. This is a considerably larger amount of energy than to make the carbon free radical (because we are stealing away an electron).

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General Energy Cycle for Carbocations - relative energy to form carbocations (all energy values in kcal/mole)

R e- H heterolytic o heat of formatio of hydrogen bond energy Hf (H ) = -52 C H C H atom, common to all cycles

o ionization Hf (H electron affinity) = -17 potential of R H

o R H Hf (R ) = + value (see table) homolytic bond Energy to form energy carbocation R-H

o o Hf (R ) = [BE+IP-EA- Hf (H )] o Compound Radical (BE) I.P. E.A.(H) Hf (H ) =energytomakeR H-H H (hydrogen carbocation) 104 313 -17 -52 (104) + (313) - (17) - (52) = +348 H3C-H H3C (methyl carbocation) 105 227 -17 -52 (105) + (227) - (17) - (52) = +263 CH3CH2-H CH3CH2 (primary carbocationl) 98 193 -17 -52 (98) + (193) - (17) - (52) = +222 95 -17 -52 (CH3)2CH-H (CH3)2CH (secondary carbocation) 169 (95) + (169) - (17) - (52) = +195 (CH3)3C-H (CH3)3C (tertiary carbocation) 92 154 -17 -52 (92) + (154) - (17) - (52) = +177 86 -17 (86) + (186) - (17) - (52) = +203 CH2=CHCH2-H CH2=CHCH2 (allylcarbocation) 186 -52 C H CH -H C H CH (benzyl carbocation) 88 -17 (88) + (165) - (17) - (52) = +184 6 5 2 6 5 2 165 -52

Common arguments for relative stabilities of free radicals and carbocations are inductive effects/hyperconjugation and resonance. Inductive effects and hyperconjugation argue that switching out a hydrogen for a carbon group allows greater electron donation to the electron deficient carbon atom (free radical or carbocation) because of increased pairs of electrons polarized towards the electron deficient centers. Carbocations are much more electron deficient than free radicals and benefit much more from this effect. The resonance argument states that an adjacent pi bond or lone pair can spread electron density through parallel p orbitals, thus reducing the energy to form a cation or free radical.

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The differences in relative carbocation stabilities parallel the trend seen in free radicals, but are greatly enhanced versus the free radical stabilities.

One could also make a steric argument for tertiary being the most stable free radical or carbocation. The geometry changes from 109o (sp3) bond angles to 120o bond angles (sp2). The ground state of a tertiary C-H bond would start at higher potential energy from crowding, which would be relieved somewhat when the fourth group is removed, providing, perhaps, part of the advantage in the tertiary reaction over secondary over primary over methyl when forming tertiary free radicals and carbocations.

R Breaking a bond is a large uphill energy transformation, C R R but less so with a sterically R CR R R crowded starting point, so Ea is a little smaller than expected. R

2 more crowded as sp3 center = higher less crowded as sp with 3 groups potential energy starting point around trigonal planar carbon with 3-4 larger groups around is slightly more stable than it tetrahedral carbon would be if groups were smaller Spectroscopy Beauchamp 13

Problem 7 – Consider the possible fragmentation of 2-methylbutane (isopentane). There are 3 types of C-C bonds that could break (b,d,f) and 4 types of C-H bonds that could break (a,c,e,g). Only consider breaking the C-C bonds (b,d,f) and the tertiary C-H bond (c). Each bond could break in two ways: either atom could be a cation and either atom could be a free radical. Calculate the energy cost for each possibility (each bonded atom as a radical and each atom as a cation). For each possibility what are the masses that would be observed at the detector (we only see cations)? This problem will require eight calculations for the four bonds considered.

CH3 CH3 b d H f high energy H C C CH electron beam b d H f 2 2 H C C CH Possible a c e g 2 2 fragmentations? a c e g H H H H H H H H 2-methylbutane Energy to rupture bonds (isopentane) radical cation (eight calculations).

b b ccddf f

Actual Mass Spectrum – tabulated and graphical. mass percent Peaks 15, 29, 43, 57 and 72 are logical. In our discussions of 15 2 fragmentation we will see how many of the other peaks are explainable. 26 4 27 43 75 eV 28 6 43 = base peak 29 60 100 isopentane 41,42 57 Many smaller 30 1 peaks not shown. 37 1 C5H12 38 3 75 39 30 CH3 57 43 40 5 29 15 29 41 88 percent CH CH3 relative H3C C 42 95 50 H 43 100 = base intensity 2 44 7 MW = 72 50 2 39 51 3 25 M+ 53 4 peak 55 10 72 56 40 57 95 0 58 6 0 25 50 75 100 71 5 mass m = 72 16 = M+ charge e

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Problem 8 – Consider the possible fragmentation of 2,2,4-trimethylpentane. There are four types of C-C bonds that could break (a, b, d, f) and 4 types of C-H bonds that could break (a, c, e, g). Only consider breaking the C-C bonds (a, b, c, d). Each bond could break in two ways: either atom could be a cation and either atom could be a free radical. Calculate the energy cost for each possibility (each bonded atom as a radical and each atom as a cation). For each possibility what are the masses that would be observed at the detector? This problem will require eight calculations for the four bonds considered (we only see cations).

CH3 CH3 high energy H2 H electron beam H2 H H3C C C C CH3 Possible a b c H3C C C C CH3 d a b c d fragmentations?

CH3 CH3 CH3 CH3 Energy to rupture bonds 2,2,4-trimethylpentane radical cation (eight calculations).

a a b b c c dd

Actual Mass Spectrum tabulated and graphical.

mass percent 27 5 29 8 39 5 40 1 41 21 42 1 43 18 53 1 55 3 56 33 57 100 = base 58 4 99 6 114 0 = M+ (missing)

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Problem 9 - Predict reasonable fragmentation patterns for n-octane and where the major ion peaks should appear. Rationalize your predictions on the basis of energetics. The mass spectrum is provided for comparison. Some of the less logical peaks will become explainable after our discussions on fragmentation. Is there a ‘logical’ peak that is missing?

Actual Mass Spectrum tabulated and graphical. mass percent percent relative base 27 20 intensity 75 eV peak 28 4 43 29 27 100 octane Many smaller 39 12 C H peaks not shown. 40 2 8 18 41 44 75 H2 H2 H2 42 15 C C C CH3

43 100 = base H3C C C C 44 3 H2 H2 H2 53 2 50 55 11 41 56 18 57 57 34 29 + 25 71 85 M 69 2 peak 70 12 114 71 20 84 7 0 85 26 0 120 86 2 25 50 75 100 mass 114 6 = M+ = m charge Z

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Special patterns of fragmentation from organic functional groups

Alkanes - Key Points (see examples above)

1. Lower mass alkyl branch fragments (2-6 C’s, masses = 29, 43, 57, 71, 85) are more intense than higher mass fragments (6). The loss of the smaller branch as the cation more commonly reaches the detector.

2. The major carbocations that form follow carbocation stabilities (R+ = 3o > 2o > 1o > Me). It is also quite possible that less stable carbocations rearrange to more stable carbocations before they reach the detector. We can’t tell by only observing the mass since they have the same number.

less stable more stable primary carbocation tertiary carbocation proposed probable fragmentation rearrangement R R

C4H9 C4H9 mass = 57can't tell which mass = 57

3. Linear alkanes more often have observable molecular ion peaks, while increased branching weakens the molecular ion peak. Fragmentation is more common at branch points. Loss of a methyl from a straight chain is considerably weaker than loss of a methyl at a branch point.

M+ = 114 (6%) M+ = 114 (3%) M+ = 114 (0%) base peak = 43 base peak = 43 base peak = 57 (M - 15) = 99 peak (0%) (M - 15) = 99 peak (1%) (M - 15) = 99 peak99 peak (6%)

4. Linear fragments often differ by 14 amu (different size branches split off between carbons in different molecules, CH2 = 14). Take another look at problem 9, just above.

5. There are often clusters of peaks around main peaks. Very large fragment peaks will have a trailing M+1 peak due to 13C isotopes (about 1% for every carbon present). A rough guide for any large peak is that it will have “M+1” peak that is about 1% its size for every carbon in the fragment due to 1% 13C isotopes at each carbon. For example, if a fragment mass had an 80% value in a five carbon fragment, the next mass peak would be expected to be 0.05x80%  4% size based on 13C isotopes. If there were 10 carbons, the next mass peak would be expected to have 0.10x80%  8% size just based on the 13C isotopes (in addition to any real fragments that might come at that value.

Spectroscopy Beauchamp 17

6. Cycloalkanes tend to have stronger molecular ion peaks (two bonds have to break) and their fragment patterns are more complicated to interpret (and we won’t try to interpret every possibility). Alkene fragmentation peaks are often subfeatures of the fragmentation pattern. Loss of “CH2CH2“ (= 28) is common, if present.

M+ = 112 (59%) M+ = 114 (6%) M-28 = 84 (39%) M-28 = 86 (2%)

7. Two masses that seem to show up in nearly every mass spectrum are 39 and 41. These may arise from resonance stabilized carbocations formed by rearrangements in the high energy electron beam. Look for peaks that extend those patterns by units of 14 (insertion of a CH2),. which are also commonly observed masses.

8. Even masses of 30, 44, 58, 72, etc. on occasion can be due to “radical-cation alkanes” that form from high energy rearrangements. Some of these masses form from other fragmentations too. But if there is no other logical reason to see one of these masses, this could be a possible explanation.

Common alkane fragmentations occur at branch points; more branches lead to more stable carbocations. However, skeletons can rearrange in almost any conceivable way possible to form o o o more stable carbocations (e.g. 3 R+ > 2 R+ > 1 R+ > H3C+). Also, alkanes can lose H2 or R-H to form alkenes, so we have to consider possible alkene rearrangements for alkanes too (see our next functional group). Smaller masses tend to be more prominent than larger masses in the mass spectrum. Perhaps they don’t have as many options for falling apart as the larger fragments do. Also, when larger fragments fall apart, they make smaller fragments.

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M+ = 114 C H 8 18 C H 71 99 C8H18 6 13 C6H13 C5H11 C4H9 C3H7 C2H5 C1H3 57 43 15 29 M+ = 114 99 85 71 57 43 57 85 29 15 actual peaks octane - all alkane fragments not observed in octane are observed, except 99. in octane mass % alkane 15.0 1 peaks 26.0 1 Only cations reach detector, so only the part with positive charge is observed at the detector. A positive charge 27.0 20 is written on all fragments to indicate that either part could retain the positive charge (in a rearranged stable form). 28.0 4 Often you can see the mass of both cations of a possible fragmentation. It is useful to look for both fragment 29.0 27 masses in the mass spectrum. Peaks related to alkene fragmentations are discussed in the next functional group. 39.0 12 40.0 2 41.0 44 42.0 15 The typical appearance of a mass spectrum is shown below. Data is also often presented as shown 43.0 100 base to the right. The intensity of the peaks tends to decrease as the fragment masses get larger. Larger 44.0 3 fragments are less likely to survive the 10-5 second trip to the detector. 51.0 1 53.0 2 54.0 1 55.0 11 56.0 18 Mostly peaks greater than 4% 43 = base 57.0 34 of the base peak are shown. 58.0 2 69.0 2 70.0 12 41 MW = 114 71.0 20 72.0 1 57 84.0 7 71 27 29 56 85 85.0 26 42 M+ = 114 28 39 55 70 86.0 2 99.0 none 114.0 6 M+ 20 30 50 60 70 80 90 100 110 120 40 115.0 1

Spectroscopy Beauchamp 19

3,4-dimethylhexane - has branches actual peaks possible alkyl in 3,4-dimethylhexane fragments mass % 15 / 99 27.0 10 28.0 1 H alkane 29 / 85 58 (4%) 29.0 26 peaks elimination reaction similar to 39.0 7 43 / 71 -H2O in alcohols to form alkene 40.0 1 41.0 43 MW = 114 57 / 57 42.0 2 43.0 58 Loss of hydrogen (H-H) or an alkane (R-H) fragment 44.0 2 generates alkenes so alkene fragmentation patterns are 51.0 1 also observed from alkane structures (see on next page). 53.0 2 the base 55.0 8 peak is 56.0 100 not expected (-H2) (-RH) 57.0 81 56 (100%) 58.0 4 alkenes 69.0 3 (see the next functional group) The base peak (56) is likely from an alkene, C H . 70.0 1 4 8 71.0 1 Remarkably, it is the major peak in the spectrum! 84.0 7 85.0 41 56 = base Mostly peaks greater than 4% 86.0 3 of the base peak are shown. 99.0 none 57 114.0 2 M+ 43 115.0 0.2 41 85 MW = 114

29 55 84 27 39 M+ = 114

20 30 40 50 60 70 80 90 100 110 120 130

It is very common to see alkene fragments in the mass spectra of alkanes, though it is very surprising to see one as the base peak, as is the case here. In the next functional group, we will compare fragmentations of alkenes and alkanes.

Alkenes - Key Points

1. A pi electron is likely to be ionized first from the HOMO of the alkene as the least tightly held electrons. Alkenes often produce stronger molecular ion peaks than alkanes because of this.

Remaining sigma bond e- R R + holds skeleton together.

oct-1-ene, MW =112 (M+ = 20%) octane, MW =114 (M+ = 6%)

2. The double bond can migrate through the skeleton (this makes it difficult to distinguish among positional isomers sharing a common skeleton).

These alkenes all look similar.

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3. Allylic cleavage is common due to resonance stabilization of cation fragment. The mass can vary depending on the groups attached to the allylic part. Look for peaks that extend this pattern by units of 14 (insertion of CH2 x1, x2, …).

R R R R R' ionization R' fragmentation R' free radical resonance stabilized carbocation is sucked away mass = 41 (R = H) 55 (R = CH3) 69 (R= CH2CH3) 83 (R = C3H7) etc.

4. McLafferty-like rearrangements are possible (similar to carbonyl pi bonds). Again, bond migration is possible. Also look for some of these fragment peaks in alkane mass spectra that have lost H2.

McLafferty-like rearrangement It is possible to see the cation charge on either fragment. Both fragments will be even unless an odd number of nitrogen atoms is present. R R H H CH2 C H2C C fragmentation C C C R C R CH2 R R H2 mass = 42 (R = H) 28 (R = H) even mass 56 (R = CH3) 42 (1 extra C) 70 (R= CH2CH3) 56 (2 extra C) 84 (R = C H ) 70 (3 extra C) 3 7

5. Cyclohexenes often undergo retro Diels-Alder reactions.

R2 R2 fragmentation is a retro-Diels-Alder reaction R1 diene dienophile R1 Only cations reach the detector. Either fragment could be positive, but usually the diene would be the more stable cation. Both fragments will be even unless an odd number of nitrogen atoms is present. Spectroscopy Beauchamp 21

Alkenes Fragmentation Patterns (Many of those below can also be found in octane, an alkane.)

Only cations reach detector, so only the part with positive charge is seen at the detector. A positive charge is written on both fragments to indicate that either could retain the positive charge (in a rearranged stable form). Often you can see both as cations from different fragmentations. The following peaks are explained by common alkene fragmentations (data on the right). Many of them are found in fragment peaks of octane, an alkane (see data on the following page). A pi bond can migrate through the skeleton to almost any conceivable position, leading to almost any variation conceivable.

McLafferty rearrangements allylic fragmentations

H

OR OR actual peaks 112 (0%) 112 (0%) 71 (20%) from octane 41 (44%) 42 (15%) 70 (12%) mass % 26.0 1 27.0 20 H 28.0 4 29.0 27 39.0 12 OR OR 40.0 2 57 (34%) 41.0 44 112 (0%) 42.0 15 112 (0%) 56 (18%) 56 (18%) 43.0 100 55 (11%) 44.0 3 53.0 2 55.0 11 H 56.0 18 OR 57.0 34 OR 58.0 2 69.0 2 112 (0%) 69 (2%) 43 (100%) 70.0 12 112 (0%) 70 (12%) 42 (15%) 71.0 20 72.0 1 84.0 7 85.0 26 86.0 2 CH3 OR 114.0 6 112 (0%) 15 (0%) 97 (0%)

H

OR OR 112 (0%) 84 (7%) 112 (0%) 28 (4%) 83 (0%) 29 (27%)

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Similar fragmentation patterns for C8H16 alkenes. Notice that octane (an alkane) has many of these same fragments.

A C E G

F H B D

A B C D E F G H octane 1-octene trans-2-octene cis-2-octene trans-3-octene cis-3-octene cis-4-octene trans-4-octene 15.0 1 15.0 1 15.0 1 15.0 1 15.0 2 15.0 1 15.0 1 26.0 1 26.0 1 26.0 1 26.0 1 26.0 2 26.0 2 26.0 1 27.0 20 27.0 25 27.0 18 27.0 25 not available 27.0 25 27.0 23 27.0 16 28.0 4 28.0 5 28.0 4 28.0 4 28.0 4 28.0 3 28.0 2 29.0 27 29.0 35 29.0 33 29.0 45 29.0 19 29.0 17 29.0 14 30.0 - 30.0 - 30.0 1 30.0 1 30.0 - 30.0 - 30.0 - 32.0 - 32.0 1 32.0 - 32.0 - 32.0 - 32.0 - 32.0 - 38.0 - 38.0 1 38.0 1 38.0 1 38.0 2 38.0 2 38.0 1 39.0 12 39.0 28 39.0 19 39.0 22 39.0 26 39.0 24 39.0 16 40.0 2 40.0 5 40.0 3 40.0 4 40.0 5 40.0 4 40.0 2 41.0 44 41.0 82 41.0 64 41.0 81 41.0 100 41.0 93 41.0 78 42.0 15 42.0 66 42.0 34 42.0 44 42.0 38 42.0 29 42.0 25 43.0 100 43.0 100 43.0 11 43.0 15 43.0 18 43.0 15 43.0 12 44.0 3 44.0 3 44.0 - 44.0 1 44.0 1 44.0 - 44.0 - 50.0 - 50.0 - 50.0 1 50.0 1 50.0 2 50.0 2 50.0 1 51.0 1 51.0 2 51.0 2 51.0 2 51.0 4 51.0 3 51.0 2 52.0 - 52.0 1 52.0 1 52.0 1 52.0 2 52.0 2 52.0 1 53.0 2 53.0 8 53.0 8 53.0 8 53.0 11 53.0 9 53.0 6 54.0 1 54.0 9 54.0 9 54.0 8 54.0 8 54.0 9.2 54.0 7 55.0 11 55.0 99 55.0 100 55.0 100 55.0 95 55.0 100 55.0 100 56.0 18 56.0 87 56.0 52 56.0 63 56.0 54 56.0 46 56.0 43 57.0 34 57.0 19 57.0 21 57.0 25 57.0 16 57.0 14 57.0 12 58.0 2 58.0 - 58.0 1 58.0 1 58.0 1 58.0 - 58.0 - 59.0 - 59.0 - 59.0 - 59.0 - 59.0 1 59.0 - 59.0 - 63.0 - 63.0 - 63.0 - 63.0 - 63.0 1 63.0 1 63.0 - 65.0 - 65.0 1 65.0 1 65.0 1 65.0 2 65.0 2 65.0 2 66.0 - 66.0 - 66.0 - 66.0 - 66.0 1 66.0 1 66.0 - 67.0 - 67.0 6 67.0 5 67.0 6 67.0 10 67.0 9 67.0 8 68.0 - 68.0 7 68.0 4 68.0 5 68.0 7 68.0 5 68.0 4 69.0 2 69.0 44 69.0 29 69.0 34 69.0 47 69.0 36 69.0 32 70.0 12 70.0 86 70.0 43 70.0 56 70.0 48 70.0 44 70.0 42 71.0 20 71.0 12 71.0 4 71.0 6 71.0 6 71.0 5 71.0 4 72.0 1 72.0 - 72.0 - 72.0 - 72.0 - 72.0 - 72.0 - 77.0 - 77.0 - 77.0 - 77.0 - 77.0 2 77.0 1 77.0 1 79.0 - 79.0 - 79.0 - 79.0 - 79.0 2 79.0 2 79.0 1 81.0 - 81.0 1 81.0 1 81.0 1 81.0 3 81.0 2 81.0 2 82.0 - 82.0 6 82.0 2 82.0 3 82.0 2 82.0 2 82.0 2 83.0 - 83.0 34 83.0 16 83.0 22 83.0 24 83.0 24 83.0 29 84.0 7 84.0 22 84.0 7 84.0 10 84.0 7 84.0 7 84.0 7 85.0 26 85.0 2 85.0 - 85.0 1 85.0 2 85.0 1 85.0 - 86.0 2 86.0 - 86.0 - 86.0 - 86.0 - 86.0 - 86.0 - 97.0 - 97.0 4 97.0 2 97.0 2 97.0 2 97.0 2 97.0 1 112.0 - 112.0 20 112.0 28 112.0 36 112.0 36 112.0 36 112.0 33 113.0 - 113.0 2 113.0 3 113.0 3 113.0 3 113.0 3 113.0 3 114.0 - 115.0 1 alkyl branch fragments = 15, 29, 43, 57, 71, 85, 99 allylic fragments = 27, 41, 55, 69, 83, 97 McLafferty fragments = 28, 42, 56, 70, 84, 98

Spectroscopy Beauchamp 23

Another Alkene Example (C7 alkene) alkenes (1-heptene, 2-heptene, 3-heptene, all of them look similar because the pi bond can migrate through the skeleton)

This example starts with hept-1-ene A pi bond can migrate McLafferty rearrangements through the skeleton to allylic fragmentations almost any conceivable H position.

57 (31%) C7H14 = 98 (14%) 42 (55%) 56 (100%) C7H14 = 98 (14%) 41 (97%) all peaks > 1% 15.0 1 18.0 1 H 26.0 2 27.0 26 28.0 5 29.0 56 43 (16%) 30.0 1 42 (55%) 38.0 2 C7H14 = 98 (14%) 56 (100%) C7H14 = 98 (14%) 55 (68%) 39.0 30 40.0 5 41.0 97 42.0 55 43.0 16 H 50.0 2 51.0 2 52.0 1 53.0 6 54.0 8 70 (44%) 28 (5%) 69 (31%) 55.0 68 C7H14 = 98 (14%) C7H14 = 98 (14%) 29 (56%) 56.0 100 57.0 31 58.0 1 67.0 2 68.0 4 69.0 31 CH3 = 15 (1%) 70.0 44 71.0 2 83.0 4 98.0 14 C7H14 = 98 (14%) 83 (31%)

alkyl branches allylic 15 (1%) McLafferty fragments fragments 29 (56%) 27 (26%) 43 (16%) 28 (5%) 41 (97%) 42 (55%) 57 (31%) 55 (68%) 71 (3%) 56 (100%) 69 (31%) 70 (44%) 85 (0%) 83 (4%)

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Alkynes - Key Points

1. Terminal alkynes have weak or missing M+ peaks (they often lose radical hydrogen), though M-1 can be very strong. H H H

R H R

M+ (M-1)+ 2. The triple bond can migrate through the skeleton (this makes it difficult to distinguish among positional isomers sharing a common skeleton).

These alkynes all look similar.

3. All alkynes give a reasonably strong m/e = 39 peak from propargylic cleavage (resonance is OK, but more electronegative sp carbocation resonance form reduces contribution). This mass can also be explained by rearrangement to from a very stable aromatic cyclypropenyl carbocation. If you look at a lot of mass spectra, this mass always shows up, even if no alkyne is present. Look for peaks that extend this pattern by units of 14 (insertion of CH2 x1, x2, …).

Only cations reach the detector. Mass 39 is in every EI mass spectrum. R' This could be because the cation is really an aromatic carbocation. H C H H R C C fragmentation resonance C also CH R C R C works R C for H C R' H radical cation mass = 39 (R = H) 53 (R = CH3) 67 (R= CH2CH3)

4. Small peaks at M=26 are probably ethyne (acetylene). H C C M = 26 H

5. McLafferty-like rearrangements are possible (similar to the alkene above and a carbonyl pi bond) R H on one or the other. R C H R H C C R fragmentation C H C H H H 40 (R = H) 28 (R = H) radical cation 54 (R = CH ) 3 42 (R = CH3) even mass 68 (R= CH CH ) 2 3 56 (R= CH2CH3) 82 (R= C H ) 3 7 70 (R= C3H7) Either fragment can be observed and both show an even mass. Spectroscopy Beauchamp 25

Example peaks from hept-1-yne:

alkynes (1-heptyne, 2-heptyne, 3-heptyne, all of them look similar because the pi bonds can migrate through the skeleton) McLafferty rearrangements A pi bond can migrate through the skeleton to allylic fragmentations almost any conceivable H position.

C H = 96 (1%) 57 (28%) 7 12 40 (12%) 56 (26%) C7H12 = 96 (1%) 39 (30%)

H

43 (4%)

42 (8%) C7H12 = 96 (1%) 53 (18%) C7H12 = 96 (1%) 54 (35%) 15 (0.5%) 29 (46%) H 43 (4%) 57 (28%) 71 (0.2%) 85 (0%)

68 (30%) 67 (44%) 29 (46%) 28 (4%) C7H12 = 96 (1%) C7H12 = 96 (1%)

CH3

15 (0.5%) 81 (100%) C7H12 = 96 (1%) mass % mass % mass % mass % mass % 26.0 1 40.0 12 53.0 18 66.0 3 81.0 100 27.0 18 41.0 71 54.0 35 67.0 44 82.0 7 28.0 4 42.0 8 55.0 51 68.0 30 95.0 9 29.0 46 43.0 4 56.0 26 69.0 2 96.0 1 57.0 28 C7H12 30.0 1 45.0 1 70.0 2 M+ = 96 37.0 1 50.0 3 58.0 1 77.0 3 38.0 3 51.0 6 63.0 2 79.0 11 1-heptyne 39.0 30 52.0 3 65.0 7 80.0 1 mass % mass % mass % mass % mass % 15.0 1 39.0 51 53.0 47 66.0 6 81.0 100 18.0 2 40.0 8 54.0 82 67.0 43 82.0 8 26.0 3 41.0 68 55.0 22 68.0 42 91.0 1 27.0 40 42.0 7 56.0 8 69.0 4 95.0 5 C H 28.0 7 43.0 26 57.0 1 77.0 5 96.0 18 7 12 97.0 2 M+ = 96 29.0 9 50.0 6 62.0 2 78.0 1 37.0 2 51.0 12 63.0 3 79.0 14 2-heptyne 38.0 4 52.0 9 65.0 10 80.0 3 mass % mass % mass % mass % mass % 79.0 32 15.0 2 39.0 43 53.0 49 65.0 21 80.0 4 18.0 1 40.0 12 54.0 25 66.0 11 81.0 93 26.0 3 41.0 84 55.0 26 67.0 100 82.0 6 27.0 23 42.0 10 56.0 5 68.0 29 91.0 2 C H 28.0 1 43.0 3 61.0 1 69.0 2 93.0 1 7 12 50.0 6 62.0 3 95.0 7 M+ = 96 29.0 14 74.0 1 37.0 2 51.0 12 63.0 5 77.0 9 96.0 70 3-heptyne 38.0 4 52.0 7 64.0 1 78.0 2 97.0 6

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Benzenoid Structures - Key Points

1. Generally, aromatics compounds show a strong M+ peak.

2. A side chain alkyl branch (RCH2-) can fragment at the benzylic position, which is proposed to rearrange to the tropylium ion showing a m/e = 91 peak. Analogous rearrangements are possible in more substituted benzenoid compounds producing different, but predictable, masses.

R R

fragmentation rearrangement R' CH2 R' CH lots of 2 resonance R'

radical cation tropylium ion, Only cations reach the detector. This mass is 91 (if an aromatic cation R = H) and even though it is a very stable cation, it (lots of resonance) rearranges to a more stable 'tropylium' carbocation. Any branches or heteroatoms would change the '91' R' = mass mass. H 91 CH3 105 C2H5 119 HO 107 H2N 106

3. Isomeric benzenes are difficult to distinguish among, as a group. Even though the structures are different, the mass spectra of the compounds are pretty much alike due to high energy rearrangements.

These isomers have similar looking mass spectra.

4. McLafferty-like rearrangements are possible, if a simple alkyl chain of three more carbons is present (oxygen can also be in the branch) and a hydrogen atom is on the gama atom. This fragmentation produces an even mass of m/e = 92 for an unsubstituted carbon chain. Substituted rings will have different masses depending on the additional atoms. Remember that part of the 92 peak is C-13 isotopes in the 91 peak (about 7x0.01 = 0.07).

H R R R R H H H C H  or C can be on either fragment C C H  H C C H H H R = mass H Both have even masses, H H if there is not an odd H 92 number of nitrogen atoms. R = mass Even mass, if there is not an CH3 106 H 28 odd number of nitrogen atoms. C H 120 2 5 CH3 42 HO 108 C2H5 56 H2N 107 C H 70 3 7 Spectroscopy Beauchamp 27

H H H H H H C H  or C can be on either fragment C C H  H O O H H 94.0 = 100% M+ = 122 (35%) 28.0 = 1%

Examples:

McLafferty rearrangements benzylic fragmentations H H H

57 (4%) 56 (0.4%) 91 (100%) C11H16 = 148 (27%) 92 (74%)

15 (0.2%) 29 (6%) 43 (1%) 57 (4%) 65 (9%) 43 (1%) 71 (0%) 77 (4%) 85 (0.2%) 105 (11%) 105 (11%) bridging phenyl group

mass % mass % mass % mass % mass % 27.0 5 52.0 1 79.0 4 104.0 3 163.0 5 29.0 6 55.0 4 82.0 1 105.0 11 39.0 6 56.0 1 83.0 2 106.0 2 41.0 8 63.0 2 89.0 1 115.0 1 C12H18 42.0 1 65.0 9 91.0 100 117.0 1 M+ = 162 43.0 17 71.0 2 92.0 95 * 119.0 3 hexylbenzene 50.0 1 77.0 5 93.0 8 133.0 5 51.0 3 78.0 6 103.0 2 162.0 33 * Only about 7% is due to 13C isotopes.

mass % mass % mass % mass % mass % 27.0 1 64.0 2 92.0 1 119.0 21 162.0 21 29.0 2 65.0 4 103.0 2 120.0 2 163.0 3 39.0 2 66.0 1 104.0 1 128.0 2 41.0 6 77.0 4 105.0 4 129.0 1 C12H18 51.0 2 78.0 2 107.0 2 131.0 3 M+ = 162 53.0 1 79.0 6 115.0 5 133.0 1 57.0 1 89.0 1 116.0 2 147.0 100 1-t-butyl-3-ethylbenzene 63.0 1 91.0 14 117.0 4 148.0 12 Notice that "91" is not logical, but it shows up.

mass % mass % mass % mass % mass % 27.0 2 78.0 2 115.0 1 39.0 3 79.0 5 117.0 1 41.0 2 91.0 6 119.0 1 51.0 2 92.0 2 134.0 23 135.0 2.6 C10H14 53.0 1 103.0 3 M+ = 135 63.0 1 104.0 2 p-propyltoluene 65.0 2 105.0 100 77.0 6 106.0 9

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Halogenated Compounds - Key Points

1. Fluorine (mass = 19) and iodine (mass = 127) have only one naturally occurring isotope, loss of either of these masses is informative (M-19, M-127). Fluorine compounds tend to show weak M+ peaks (or none at all). When iodine is lost, there can be a big hole (= 127) in the middle of the mass spectrum.

2. Chlorine has two isotopes (35 and 37) which occur in a 3:1 ratio; this is easily observed when there is a molecular ion and in any fragments that retain the chlorine. An M-35 peak is informative, and M-36 corresponds to loss of HCl.

3. Bromine has two isotopes (79 and 81) which occur in a 1:1 ratio; this is easily observed when there is a molecular ion and in any fragments that retain the bromine. An M-79 peak is informative, and M-80 corresponds to loss of HBr.

4. Loss of “X” is common (see above) and loss of HX can occur with fluorine (M-20), chlorine (M-36), bromine (M-80).

5. Loss of an alkyl radical and formation of a five atom ring or three atom ring is possible with chains of C5 and longer with bridging chlorine, bromine or iodine (also true for sulfur).

X X R R  fragmentation    Free radicals are sucked     away by the vacuum pump. Cations reach the detector, will see this mass. X = mass Cl 91 Br 135 I 183

X X R fragmentation

R Cations reach the detector, Free radicals are sucked will see this mass. away by the vacuum pump. X = mass Cl 63 Br 107 I 155

Spectroscopy Beauchamp 29

Examples mass % mass % alkyl branches Cl 15 (1%) Cl Cl 15.0 1 55.0 81 29 (32%) 26.0 2 56.0 56 1-chlorhexane 43 (72%) 84 (4%), minus HCl 27.0 27 57.0 15 C6H13Cl = 120 57 (15%) other alkene fragments 28.0 5 63.0 5 63 (5%) 29.0 32 65.0 2 71 (3%) 91 (100%) allylic 85 (0.7%) McLafferty 39.0 17 67.0 3 28 (5%) 27 (27%) 40.0 3 69.0 22 42 (45%) 41 (59%) 41.0 59 70.0 2 56 (56%) 63 (81%) 42.0 45 71.0 3 70 (3%) 43.0 72 84.0 4 84 (1%) 44.0 2 91.0 100 49.0 3 92.0 4 91.0 100 53.0 4 35 37 93.0 32 93.0 32 Cl and Cl 54.0 4 94.0 1

alkyl branches mass % mass % Br 15 (1%) Br Br 29 (21%) 15.0 1 58.0 4.9 1-bromorhexane 43 (66%) 84 (4%), minus HBr 26.0 1 69.0 .5 C H Br = 165 57 (100%) 27.0 16 70.0 3 6 13 107 (1%) other alkene fragments 28.0 3 71.0 3 71 (3%) 135 (8%) McLafferty allylic 85 (18%) 29.0 21 81.0 1 28 (3%) 27 (16%) 39.0 11 83.0 1.5 42 (10%) 41 (42%) 40.0 2 84.0 1 56 (5%) 63 (0%) 41.0 42 85.0 18 70 (3%) 42.0 10 86.0 1 84 (1%) 43.0 66 99.0 14 44.0 2 100.0 1 91.0 100 53.0 2 107.0 1 93.0 32 35Cl and 37Cl 54.0 1 109.0 1 55.0 6 135.0 8 91.0 100 56.0 5 137.0 8 93.0 32 35Cl and 37Cl 57.0 100

alkyl branches mass % mass % I 15 (1%) I I 27.0 14 29 (15%) 1-iodohexane 84 (4%), minus HI 28.0 3 43 (100%) 29.0 15 C6H13I = 212 57 (11%) 107 (2%) other alkene fragments 39.0 7 71 (0%) 183 (0%) McLafferty allylic 40.0 1 85 (50%) 28 (3%) 27 (14%) 41.0 25 42 (3%) 41 (25%) 42.0 3 56 (2%) 63 (0%) 43.0 100 70 (0%) 44.0 3 84 (0%) 53.0 1 55.0 6 56.0 2 57.0 11 85.0 50 86.0 3 155.0 2 212.0 4

1-iodopropane 2-iodopropane mass % mass % I alkyl branches I 15.0 2 15.0 1 15 (2%) (1%) 26.0 2 29 (0%) (0%) 42, minus HI 26.0 1 1-iodopropane 27.0 32 27.0 28 43 (100%) (100%) other alkene fragments 28.0 2 C3H7I = 170 57 (0%) (0%) 28.0 2 not possible McLafferty allylic 38.0 2 38.0 2 71 (0%) (0%) 28 (3%) (2%) 27 (32%) (28%) 39.0 11 39.0 12 85 (0%) (0%) 40.0 2 I 42 (3%) (4%) 41 (37%) (36%) 40.0 2 56 (0%) (0%) 63 (0%) (0%) 41.0 37 41.0 36 70 (0%) (0%) 42.0 3 42.0 4 I 84 (0%) (0%) 43.0 100 43.0 100 Almost identical 155 (0%) 2-iodopropane 44.0 3 44.0 3 mass spectra. 127.0 5 127.0 6 C3H7I = 170 I = 127.0 (5%) (6%) 128.0 1 128.0 2 HI = 128.0 (1%) (2%) 170.0 24 170.0 24

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Alcohols - Key Points

1. Alcohols generally have weak M+ peaks. Tertiary alcohols often do not have an M+ peak. However, if you had an IR, you would know an alcohol was present from the OH and CO bands. Additional evidence would be present in the proton and carbon 13 NMR spectra, if available.

2. Loss of water (M-18) is common; more so with straight chains and less so with branched alcohols.

H O M-18 fragmentation H H H R' O R' This can lead to alkene fragmentations.

OH OH OH OH

linear has branch has branch has branch 15.0 3 15.0 2 15.0 3 15.0 2 26.0 3 26.0 2 26.0 1 26.0 2 27.0 33 27.0 10 27.0 4 27.0 23 28.0 12 28.0 52 28.0 1 28.0 12 29.0 16 29.0 6 29.0 6 29.0 8 31.0 83 31.0 17 31.0 27 31.0 40 H2C=OH 39.0 11 39.0 3 39.0 6 39.0 14 40.0 4 40.0 1 40.0 1 40.0 3 41.0 66 41.0 12 41.0 21 41.0 57 42.0 32 42.0 1 42.0 1 42.0 59 43.0 59 43.0 9 43.0 9 43.0 100 45.0 1 45.0 7 45.0 100 45.0 4 (M-29) = C2H5 53.0 1 53.0 1 53.0 1 53.0 1 55.0 14 55.0 2 55.0 2 55.0 6 56.0 100 56.0 2 56.0 3 56.0 5 (M-18) = H2O 57.0 6 57.0 2 57.0 8 57.0 3 59.0 100 59.0 0.3 59.0 20 59.0 6 (M-15) = CH3 74.0 0.6 74.0 0.2 74.0 0 74.0 13 M+ peak The base peak is bolded in each example.

3. “Alpha” cleavage is common because a resonance stabilized carbocation can form three possible o ways in tertiary alcohols where R1 ≠ R2 ≠ R3. (two ways with 2 alcohols). Often all are observed, when present.

R1 R1 fragmentation H O C R2 H O C R2 H O C R2

R3 R3 R3 "X" lone pair electrons fill in loss of electrons at carbocation site. This is a common radical cation fragmentation pattern for any atom that has a lone pair of electrons (oxygen = alcohol, ether, ester; nitrogen = amine, amide; sulfur and halogens). Loss of R1, R2 or R3 is possible.

Spectroscopy Beauchamp 31

4. Cyclic alcohols tend to show stronger M+ peaks than linear chains. OH OH OH OH

M+ = 72 (1%) M+ = 86 (9%) M+ = 100 (3%) M+ = 114 (2%) M-18 = 54 (1%) M-18 = 68 (7%) M-18 = 82 (46%) M-18 = 96 (23%) M-28 = 44 (100%) M-28 = 58 (14%) M-28 = 72 (7%) M-28 = 86 (4%) base peak = 44 (100%) base peak = 57 (100%) base peak = 57 (100%) base peak = 57 (100%) OH OH OH OH

M+ = 74 (0.6%) M+ = 88 (0%) M+ = 102 (0%) M+ = 116 (0%) M-18 = 56 (100%) M-18 = 70 (51%) M-18 = 84 (9%) M-18 = 98 (6%) base peak = 56 (100%) base peak = 42 (100%) base peak = 56 (100%) base peak = 70 (100%)

5. When oxygen is present in any molecule, it is likely that mass 31 will be present.

H O C H H O C H

H H Mass = 31 is almost always present when oxygen is present, especially in alcohols.

Example OH

H (-H2O) 98 (4%), minus H2O loss of water other alkene fragments C7H16O M+ = 116 from either side McLafferty allylic 28 (0%) 27 (5%) 42 (4%) 41 (10%) See alkene fragmentations earlier. The 56 (7%) 55 (15%) pi bond can move around the carbon 70 (5%) 69 (3%) skeleton, which can also rearrange. 84 (0%)

OH 98 alkyl branches actual peaks a b a 15 (1%) 29 (5%) mass % b CH3 43 (8%) 27.0 5 C5H11 71 57 (4%) 29.0 5 C7H16O M+ = 116 71 (1%) 31.0 2 15 85 (0%) 39.0 3 H H 41.0 10 O 42.0 4 O H 43.0 8 45 O 44.0 7 HC CH 45.0 100 CH 46.0 2 3 101 CH2 55.0 15 31 56.0 7 Many types of skeletal rearrangements are possible using a such high energy electron beam. not logical, 57.0 4 The "31" fragment does not make sense at a 2o or 3o ROH, but is often observed (in ethers too). but observed 69.0 3 70.0 5 83.0 9 98.0 4 101.0 4

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Ethers - Key Points

1. Ethers tend to have stronger M+ peaks than alcohols, but still can lose ROH the way that alcohols lose H2O. R O R = mass H 18 fragmentation H R CH 32 H 3 R' O C H 46 R' 2 5 C3H7 60 from either side

2. Alpha cleavage is common from either side and further loss of the carbonyl fragment is possible.

R1 R1 fragmentation R' O C R2 R' O C R2 R' O C R2

R3 R3 R3 "X" lone pair electrons fill in loss of electrons at carbocation site. This is a common radical cation fragmentation pattern for any atom that has a lone pair of electrons (oxygen = alcohol, ether, ester; nitrogen = amine, amide; sulfur and halogens). Loss of R1, R2 or R3 is possible.

3. Loss of an oxygen carbon branch is also possible (from either side).

R1 R1

fragmentation C R2 R' O C R2 R' O

R3 R3 We only see the cations. The fragmentation could potentially occur from either side. radical cation

56 (24%), minus ROH a 28 (4%), minus ROH (-ROH) mass % O OH2 other alkene fragments b a 15.0 1 46 (0%) 56 (24%) McLafferty allylic 18.0 3 H H M+ = 102 (4%) loss of alcohol b 28 (4%) 27 (12%) 26.0 1 from either side HO 42 (3%) 41 (26%) 27.0 12 56 (24%) 55 (6%) 28.0 4 28 (4%) 74 (0%) 70 (0%) 69 (0%) 29.0 27 84 (0%) 31.0 57 39.0 5 41.0 26 c d H2 d c C 42.0 3 CH 3 O H C CH 43.0 6 O O 2 3 44.0 1 15 (1%) 87 (2%) 43 (6%) 45.0 10 C H O M+ = 102 (4%) 59 (100%) 47.0 1 6 14 55.0 6 56.0 24 H 57.0 31 e f ef O 58.0 1 59.0 100 O O 60.0 3 O CH 57 (31%) 2 73.0 8 29 (27%) 73 (8%) 45 (10%) M+ = 102 (4%) 31 (57%) 87.0 2 C6H14O 101.0 1 not logical, 102.0 4 but observed

Spectroscopy Beauchamp 33

Thiols and Thioethers - Key Points

1. The M+2 peak with a single sulfur adds an extra 4.4% to this peak relative to the M+ peak (in addition to other M+2 contributions). Other than chlorine and bromine, this is the most significant M+2 contributor to common organic molecules.

2. Loss of H2S (M-34) is possible for thiols and RSH for sulfides (loss of CH3SH = (M-48)).

R M - (RSH mass) S R = mass H 34 R H fragmentation CH3 48 H R' S C2H5 62 R' C H 76 This can lead to alkene fragmentations. 3 7

3. “Alpha” cleavage is possible because a resonance stabilized carbocation can form three possible ways. Often all are observed, when present.

R1 R1 fragmentation R S C R2 R S C R2 R S C R2

R3 R3 R3 "X" lone pair electrons fill in loss of electrons at carbocation site. This is a common radical cation fragmentation pattern for any atom that has a lone pair of electrons (oxygen = alcohol, ether, ester; nitrogen = amine, amide; sulfur and halogens). Loss of R1, R2 or R3 is possible. 4. If a side chain has five or more atoms then  cleavage is possible with ring formation (see the halogens). Beta (β) cleavage is also reasonable.

R R

S S R R  fragmentation    Free radicals are sucked     away by the vacuum pump. Cations reach the detector, will see this mass. R = mass H 89 CH3 103 C2H5 117

R S R S R fragmentation   R Cations reach the detector, Free radicals are sucked will see this mass. away by the vacuum pump. R = mass H 61 CH3 75 C2H5 89 y:\files\classes\Spectroscopy Book home\1 Spectroscopy Workbook, latest MS full chapter.doc Spectroscopy Beauchamp 34

Example H alkyl branches H mass % mass % SH 15 (1%) S S 26.0 1 55.0 35 29 (15%) 27.0 16 1-hexanethiol 43 (48%) 84 (16%), minus H2S 56.0 100 28.0 4 57.0 7 C6H14S = 118 57 (7%) other alkene fragments 61 (10%) 29.0 15 59.0 2 120 (5.3%) 71 (0%) 89 (3%) McLafferty allylic 35.0 2 85 (2%) 60.0 2 28 (4%) 27 (16%) 39.0 9 61.0 10 42 (32%) 41 (35%) 40.0 2 62.0 1 56 (100%) 55 (35%) 41.0 35 69.0 25 70 (2%) 69 (25%) 42.0 32 70.0 2 84 (16%) 83 (1%) 43.0 48 83.0 1 44.0 2 84.0 16 45.0 4 85.0 2 46.0 2 89.0 3 47.0 15 118.0 30 48.0 1 119.0 2 53.0 2 120.0 1.6 54.0 3 mass % mass % H H alkyl branches 15.0 1 55.0 17 S 15 (1%) S S 26.0 3 56.0 68 29 (50%) 56 (68%), minus H2S 27.0 36 57.0 17 butyl ethyl sulfide 43 (4%) other alkene fragments 28.0 9 58.0 3 C6H14S = 118 57 (0%) 29.0 50 59.0 6 120 (4.8%) 71 (0%) 89 (25%) 61 (38%) McLafferty allylic 34.0 1 60.0 6 85 (0%) 28 (9%) 27 (36%) 35.0 9 61.0 38 42 (4%) 41 (49%) 39.0 11 62.0 47 CH3 H S = 34 (1%) 56 (68%) 55 (17%) 40.0 2 63.0 20 2 S 70 (0%) 69 (0%) 41.0 49 75.0 100 84 (0%) 83 (0%) 42.0 4 76.0 8 43.0 4 77.0 5 45.0 12 89.0 25 75 (100%) 46.0 12 90.0 3 47.0 48 103.0 2 S S 48.0 6 118.0 56.4 = M+ (M-57) = 89 (38%) (M-29) = 89 (25%) 53.0 2 119.0 4 54.0 1 120.0 2.7 = M+2

Phenols - Key Points

1. Phenols tend to have intense M+ peaks. (See below = 100% and 36%.)

2. Loss of CO with extensive rearrangement is common. R R OH R1 R O fragmentation loss of carbon monoxide...? CO R = mass radical cation H 65 CH3 79 C2H5 93

3. A hydroxy tropylium ion with no other substituents has a m/e = 107. R R1 OH R' H R = mass fragmentation CH 107 O Lots of 3 resonance. C2H5 121 etc. radical cation

Spectroscopy Beauchamp 35

Examples mass % mass % OH alkyl branches 15 (0%) 27.0 2 62.0 2 29 (0.8%) 37.0 2 63.0 4 43 (0.4%) 38.0 4 64.0 1 57 (0%) 39.0 14 65.0 17 71 (0%) 65 (17%) 39 (14%) 40.0 9 66.0 23 phenol 85 (0%) 47.0 4 67.0 2 C6H60 = 94 (100%) 50.0 3 74.0 1 M+1 = (7%) 51.0 3 93.0 2 53.0 2 94.0 100 55.0 7 95.0 7 61.0 1

alkyl branches OH 15 (0.4%) R 29 (0.4%) OH mass % mass % 43 (0.4%) 27.0 3 65.0 3 57 (0%) 38.0 1 77.0 13 71 (0%) R=H 65 (3%) 39 (6%) 39.0 6 78.0 3 85 (0%) R=CH 79 (2%) 41.0 1 79.0 2 p-ethylphenol 3 50.0 3 91.0 4 R=C2H5 93 (1%) C H 0 = 122 (36%) 27 (3%) 107 (100%) 51.0 5 94.0 1 6 6 41 (1%) 52.0 3 103.0 2 M+1 = (3%) OH 55 (3%) allylic R 53.0 2 107.0 100 69 (0%) 55.0 3 108.0 8 83 (0%) 62.0 1 121.0 3 63.0 2 122.0 36 123.0 3 121 (3%)

Amines - Key Points

1. Amines often have weak or absent M+ peaks. An odd number of nitrogen atoms produces an odd molecular ion peak.

H2 C H H2 H C N C H 3 C H O CnH2n+2Om n 2n+2+N m H3C O H Molecules made with an odd number of Molecules made with C, H, S, O, halogens nitrogen atoms have odd molecular masses and an even number of nitrogen because they have an odd number of hydrogens. atoms have even molecular masses.

2. Alpha cleavage is usually a major fragmentation pattern in a manner similar to alcohols and ethers.

R R1 1 mass all R = H 30 fragmentation R' N C R R' N C R R' N C R2 2 one CH 44 2 resonance 3 C2H5 58 R" R3 R" R3 R" R3 etc. The fragment mass depends on what is present in the "R" groups. If all radical cation R groups are "H" (H2N=CH2 ) then the mass will be 30, which shows up in almost every amine compound examined, even tertiary amines.

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3. Loss of a branch at nitrogen is also possible in a manner similar to alcohols and ethers.

R1 R1 fragmentation R' N R' N C R2 CR2 R" R" R3 R3 radical cation The fragment mass depends on what is present in the "R" groups and which fragment retains the cation charge.

4. Aromatic amines generally show intense M+ peaks.

R1 odd mass NH2 R' H R' = mass 1. fragmentation H 106 R N Lots of 2. rearrangement resonance. CH3 120 C2H5 134 H etc. R' radical cation odd mass even mass

Examples

mass % 56 (6%), minus RNH2 15.0 1 a b other alkene fragments 18.0 2 (-ROH) 27.0 7 N McLafferty allylic b 28.0 8 a 28 (8%) 27 (7%) 29.0 18 H H H 42 (4%) 41 (18%) 30.0 100 loss of amine 56 (6%) from either side 56 56 55 (7%) 31.0 1 n-isobutyl-sec-butylamine 70 (2%) 69 (0%) 39.0 5 M+ = 129 (1%) 84 (2%) 41.0 18 C H N 42.0 4 8 19 43.0 2 d c 44.0 53 C H 45.0 1 e 2 5 N c H 55.0 7 56.0 6 N H 29 (18%) 100 (18%) 57.0 24 58.0 20 70.0 2 d 72.0 6 n-isobutyl-sec-butylamine CH N 84.0 2 3 H M+ = 129 (1%) 86.0 66 15 (1%) 114 (8%) 87.0 4 100.0 67 e 101.0 5 114.0 8 NH2 alkyl branches 128.0 1 30 (100%) 29 (18%) 129.0 1 C3H7 N CH2 43 (2%) H 57 (24%) 86 (66%) 43 (2%) not logical, but observed 71 (0%) and is even the base peak 85 (0%)

Spectroscopy Beauchamp 37

a

NH N (-ROH) 2 a 45 (0%) 56 (3%) See alkene b H fragmentations above. b H M+ = 101 (9%) H H2N butylethylamine 28 (5%) 73 (0%) mass % c d c 15.0 1 18.0 1 N CH3 27.0 5 H N 28.0 5 15 (1%) H C H N M+ = 101 (9%) 86 (2%) 29.0 8 6 15 30.0 33 butylethylamine d 39.0 2 H2 C 41.0 4 42.0 3 N H2C CH3 58 (100%) H 43 (2%) 43.0 2 44.0 10 e 56.0 3 ef 57.0 3 58.0 100 N HN 59.0 4 NH H 29 (8%) 72 (0%) 2 86.0 2 NH4 C6H15N M+ = 101 (9%) 100.0 2 f 18 (1%) 101.0 9 butylethylamine CH2 30 (33%) NH 44 (10%) 57 (3%)

Carbonyl Compounds (aldehydes, ketones, esters, acids, amides, acid chlorides) - Key Points

1. M+ peaks are often observable (though they can be weak or absent). Several examples are provided below.

2. Alpha cleavage is possible from either side. Usually the more stable cation forms in greater amount. It is best to look for both possibilities.

O R1 C O R1 C O

C R1 R2 O CR O CR radical cation 2 2 R or R can be lost from 1 2 An oxygen lone pair paritally fills in the loss of electrons at the aldehydes, ketones, acids, carbocation site via resonance. This is a common fragmentation esters, amides, acid chlorides, pattern for any carbonyl compound and can occur from either etc. side, though some are more common than others.

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3. Alpha cleavage can be followed by loss of CO (another -28). That would leave the side branches as observable peaks, plus any further fragment branches from those peaks.

R C O 1 R1 C O R1 loss of Subsequent loss of CO is possible after  fragmentation, so not only can you see loss of an  branch you can also see the mass of an  branch. CO R O CR2 O CR2 2

4. McLafferty rearrangements are common with at least three carbons in a side chain. Cleavage occurs between Cα and Cβ.

R H H O C Positive charge can be on R  R O either fragment, which typically has an even mass. C  R C C R C R C 1  R R C = alpha position C R 1   = beta position  R R  = gamma position R radical cation R R This is another common fragmentation pattern for carbonyl compounds (and other pi systems as well: alkenes, alkynes, aromatics, nitriles, etc.). If the pi bond has at least 3 additional nonhydrogen atoms attached and a hydrogen on the "gamma" atom, the branch can curve around to a comfortable 6 atom arrangement and the pi bond can pick up a hydrgen atom and cut off a fragment between the C and C positions. The positive charge can be seen on either fragment and usually the fragments have an even mass (unless there is an odd number of nitrogen atoms). The mass of either fragment depends on what "R"s are.

The bottom line is there are several ways that carbonyl (C=O) functionality can fall apart. It is best to look for all possibilities. See the last example in this example list below (ketone).

Carbonyl Examples

Carboxylic Acids mass % Loss of side chain, then CO (?) O 18.0 2 OH 26.0 2 a O H 27.0 17 28.0 4 O 17 (0.4%) C 99 (0.8%) 29.0 14 a b 71 (2%) 30.0 1 28 (5%)* 31.0 2 HO alkyl branches 39.0 10 O 15 (0.9%) 40.0 2 b 41.0 26 C6H12O2 = 116 (0%) 29 (14%) 71 (2%) 43 (14%) 42.0 7 HO 57 (12%) 43.0 14 45 (100%) 71 (2%) 45.0 9 *28 could also be ethene 85 (0.4%) 53.0 1 99 (0.8%) 55.0 10 McLafferty alkenes 56.0 8 57.0 12 H H McLafferty allylic 58.0 6 O O 59.0 3 O 60.0 100 HO 61.0 9 HO 69.0 3 HO 56 (8%) 41 (26%) 70.0 3 60 (100%) 55 (10%) 71.0 2 C6H12O2 = 116 (0%) 28 (4%) 69 (3%) 73.0 44 42 (7%) (M-29) = 87 (11%) hexanoic acid 83 (1%) 74.0 7 70 (3%) 83.0 1 87.0 11

Spectroscopy Beauchamp 39

Esters mass % Loss of side chain, then CO (?) 15.0 10 18.0 1 26.0 1 O H3CO O 27.0 11 a 28.0 2 O 29.0 12 a b 31 (2%) C 31.0 2 99 (19%) 28 (2%)* 71 (10%) 39.0 7 40.0 1 CH O 3 alkyl branches 41.0 17 O 42.0 6 15 (10%) 43.0 31 C7H14O2 = 130 (0.4%) b 29 (12%) 44.0 2 43 (31%) 45.0 2 CH O 71 (10%) 57 (4%) 53.0 1 3 71 (10%) 59 (15%) *28 could also be ethene 55.0 9 85 (0.1%) 56.0 2 99 (19%) alkenes 57.0 4 McLafferty 59.0 15 H McLafferty 69.0 2 O H allylic O 70.0 3 O CH3O 71.0 10 73.0 1 74.0 100 CH O 3 56 (2%) 75.0 5 H3CO 41 (17%) 87.0 32 55 (9%) 74 (100%) 28 (2%) (M-29) = 101 (8%) 88.0 4 C H O = 130 (0.4%) 69 (2%) 99.0 19 7 14 2 42 (6%) 83 (0%) 70 (3%) 100.0 1 methyl hexanoate 101.0 8

Aldehyde mass % 15.0 2 18.0 1 Loss of side chain, then CO (?) 26.0 3 27.0 34 H O a O 28.0 8 29.0 33 C 30.0 2 1 (?) 31.0 2 99 (0.4%) 71 (7%) OH 28 (8%)* 38.0 2 a b 39.0 20 alkyl branches 40.0 4 O 15 (2%) 41.0 69 H 29 (33%) 42.0 11 b 43 (55%) 43.0 55 C6H12O = 100 (0.4%) 57 (38%) 44.0 100 H hexanal 71 (7%) 71 (7%) 45.0 20 29 (33%) 85 (0.3%) 50.0 1 *28 could also be ethene 99 (0.4%) 51.0 1 53.0 3 54.0 2 alkenes 55.0 15 McLafferty 56.0 82 McLafferty 57.0 38 H allylic H 58.0 9 O O 60.0 4 O H 67.0 8 69.0 1 56 (82%) 71.0 7 H 41 (69%) 55 (15%) 72.0 17 28 (8%) (M-29) = 71 (7%) 73.0 2 C6H12O = 100 (0.4%) 44 (100%) 69 (1%) 42 (11%) 83 (1%) 81.0 1 hexanal 70 (0%) 82.0 13 83.0 1

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Ketone

Loss of side chain, then CO (?) O CH3 O a mass % 15 (4%) C 15.0 4 H 99 (4%) 28 (2%)* 71 (14%) 18.0 2 O a 27.0 9 b alkyl branches 28.0 2 15 (4%) 29.0 9 O 29 (9%) 39.0 7 43 (100%) 40.0 1 C7H14O = 114 (10%) b 57 (2%) 41.0 12 2-heptanone 71 (14%) 42.0 3 71 (14%) 85 (3%) 43.0 100 43 (100%) 99 (4%) 44.0 2 *28 could also be ethene 45.0 1 53.0 1 McLafferty alkenes 55.0 5 McLafferty H 56.0 2 H allylic 57.0 2 O O O 58.0 91 59.0 15 71.0 14 56 (2%) 41 (12%) 72.0 4 85.0 3 55 (5%) (M-29) = 85 (3%) C7H14O = 114 (10%) 58 (91%) 28 (2%) 69 (0%) 99.0 4 113.0 2 2-heptanone 42 (3%) 83 (0%) 70 (0%) 114.0 10 115.0 1

Amide Loss of side chain, then CO (?) O NH4 O a 18 (2%)=NH4 99 (1%) C O 98 (0.2%) 28 (2%)* 71 (2%) a b alkyl branches 15 (0%) mass % O H2N 29 (8%) 18.0 2 18 could be 43 (26%) 27.0 9 b 57 (2%) C H NO = 115 (0.6%) 28.0 2 6 13 NH4 or H2O 71 (2%) H2N 71 (2%) 29.0 8 hexanamide 44 (29%) 85 (0%) 39.0 6 *28 could also be ethene 99 (1%) 41.0 12 42.0 4 alkenes McLafferty 43.0 26 44.0 28 H H McLafferty allylic 45.0 1 O O O 55.0 4 H2N 57.0 2 59.0 100 H N 56 (0%) 60.0 3 2 H2N 41 (12%) 71.0 2 28 (2%) 55 (4%) (M-29) = 86 (9%) 72.0 19 59 (100%) C6H13NO = 115 (0.6%) 42 (4%) 69 (0%) 73.0 4 83 (0%) hexanamide 70 (0%) 86.0 9 99.0 1

Spectroscopy Beauchamp 41

Full example for 2-methyl-4-heptanone

2-methylheptan-4-one Mostly peaks greater than 5% 27.0 17 57.0 100 O of the base peak are shown. 28.0 2 58.0 27 29.0 17 59.0 1 39.0 11 69.0 2 40.0 2 70.0 1 57 = base 41.0 36 71.0 70 C H O 72.0 3 8 16 43 71 42.0 5 MW = 128 43.0 73 85.0 72 44.0 3 86.0 11 53.0 1 113.0 6 55.0 2 128.0 23 41 58 56.0 1 129.0 2 27 29 M+ = 128 39 86 113 28 42 100

120 130 20 30 40 50 60 70 80 90 100 110 a = only see the fragment that b = only see the fragment that H H retains the positive charge retains the positive charge O 2 McLafferty a H b H possibilities O O

b a and b a 28 (2%) 42 (5%) C8H16O = 128 (23%) 86 (11%) 100 (0.4%)

c = only see the fragment that Lose c retains the positive charge O left Lose c branch O CO O C C 28 (2%) 57 (100%) 43 (73%) C8H16O = 128 (23%) 71 (70%)

reasonable mass peaks d = only see the fragment that 128 100 Lose d retains the positive charge 86 O d right Lose branch 85 O CO O 71 C C 57 43 28 (2%) C H O = 128 (23%) 85 (72%) 57 (100%) 42 8 16 43 (73%) 28

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Nitriles - Key Points

1. Usually have weak M+ peaks. An odd number of nitrogen atoms produces an odd molecular ion peak. H2 Compare. CnH2n-2+N H2 CnH2n-2 C C H3C C C H N H3C C C H N 3 5 4 6 MW = 55 CH MW = 54

Nitriles made with an odd number of Alkynes made with C and H nitrogen atoms have odd molecular masses have even molecular masses. because they have an odd number of hydrogens.

2. With side chains of three carbons or longer McLafferty rearrangements are possible.

H R R H HN N C C ...or... fragmentation C C C odd CH even CH mass odd mass R R mass R R mass = 41 (R = H) mass = 28 (all H) radical cation 55 (R = CH3) 42 (1R = CH3) 69 (R= CH2CH3) 56 (1R= CH2CH3) 83 (R = C3H7) 70 (1R = C3H7) Nitrile McLafferty can cut off a fragment between the C and C positions. Either fragment can be observed (if the cation) and the one with the nitrogen atom will show an odd mass.

3. Alpha cleavage is possible.

N R C N even C C fragmentation odd odd mass R mass C mass radical cation The detector sees cations. Radicals are pumped away.

Spectroscopy Beauchamp 43

Example

mass % 15.0 2 Loss of side chain, then CN (?) alkyl branches 26.0 4 N H 15 (2%) 27.0 33 28.0 9 N a 29 (43%) C 43 (32%) 29.0 43 a 57 (28%) 30.0 1.6 hexanenitrile 26 (5%) 71 (1%) 37.0 1 71 (1%) 85 (0%) 38.0 3 39.0 22 C H N = 97 (0.8%) 6 11 40.0 5 perhaps...? 41.0 100 H 27 (33%) H 42.0 14 NH 43.0 28 NH H2CCH b 50.0 1 43 (32%) 54 (82%) or 51.0 2 42 (14%) 55 (42%) 52.0 3 HCNH b 41 (100%) 56 (4%) 53.0 4 54.0 82 55.0 42 alkenes 56.0 4 McLafferty 57.0 32 McLafferty 58.0 1 H H allylic 66.0 1 N N 67.0 1 68.0 30 69.0 23 56 (4%) 41 (100%) 70.0 4 55 (42%) 71.0 1 28 (9%) 69 (23%) 82.0 24 C H N = 97 (0.8%) 41 (100%) 6 11 42 (14%) 83 (1%) 83.0 1 70 (4%) 96.0 12 hexanenitrile 97.0 1 similar masses

These are some of the more common organic functional group fragmentation patterns in EI mass spectroscopy. Most of the examples presented here are very simple monofunctional compounds. When more functional groups are present, more complexity is expected and it gets increasingly difficult to make definitive conclusions on the basis of mass spectroscopy. Even with simple monofunctional group compounds, we have seen that functional groups can change through rearrangements possible due to the high energy of ionization (e.g. alkanes  alkenes). If you specialize in other specific patterns of functionality in your work, you will become familiar with useful mass spectral features of those groups. For us, the molecular weight is the primary information we seek from a mass spectrum, assisting us toward our main goal of determining organic structures from the available spectra. A one page summary sheet showing many of the fragmentation patterns above is provided on the next page, and the following page shows common fragments and their extended variations. These two pages will explain most of what you will encounter as a burgeoning mass spectroscopist.

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Common fragmentation patterns in mass spectroscopy (only cations are observed) 1. Fragment a branch next to a pi bond (α cleavage)

R R Characteristic carbocation stability also applies. C C C C C C C C C o o o 3 R > 2 R > 1 R > CH3

radical cation Pi electrons partially fill in loss of electrons at carbocation pi bond of an alkene, site via resonance. This is a common fragmentation We only see the cationic fragments. The alkyne or aromatic pattern for alkenes, alkynes and aromatics. radical fragments are lost to the vacuum.

2. Fragment a branch next to an atom with a lone pair of electrons

R XC X C R XC

radical cation X lone pair partially fills in loss of electrons at carbocation site via resonance. This is a common fragmentation pattern for any atom that has a lone pair of electrons (oxygen = alcohol, ether, ester; adjacent lone pair ofan nitrogen = amine, amide; sulfur = thiol, sulfide, etc.) Alcohols often lose water (M-18), ethers can oxygen or nitrogen atom lose ROH, primary amines can lose ammonia (M-17), etc.

3. Fragment a branch next to a carbonyl (C=O) bond…and possible subsequent loss of carbon monoxide, CO loss of a R1 R1 C O R1 C O O C O b a loss of C b R2 R1 R2 O CR2 O CR2 O C R1 or R2 can be lost from aldehydes, ketones, An oxygen lone pair partially fills in the loss of electrons Subsequent loss of CO is possible after acids, esters, amides...etc. at the carbocation site via resonance. This is a common  fragmentation, so not only can you fragmentation pattern for any carbonyl compound and see loss of an a branch, you can also can occur from either side, though some are more common see the mass of an  branch. than others.

4. McLafferty Rearrangement H H The positive charge can be on O O C C either fragment, which typically  have even masses (unless an odd C C C number of N is present). C R C R1 C 1   = alpha position  = beta position OR cation fragment radical cation cation fragment  = gama position

This is another common fragmentation pattern for carbonyl compounds (and other pi systems as well: alkenes, aromatics, alkynes, nitriles, etc). If the pi bond has at least 3 additional nonhydrogen atoms attached and a hydrogen on the "gama" atom, the branch can curve around to a comfortable 6 atom arrangement and the pi bond can pick up a hydrogen atom and cut off a fragment between the C and C positions. The positive charge can be seen on either fragment and usually the fragments have an even mass (unless there is an odd number of nitrogen atoms in the observed fragment). Knowing these few fragmentation patterns will allow you to make many useful predictions and interpretations in mass spectroscopy. Also loss of small molecules is common, producing an even mass if no nitrogen is present: H2O = 18, H2S = 34, CH3OH = 32, C2H5OH = 46, NH3 = 17, CH3CO2H = 62, HF = 20, HCl = 36/38, HBr = 80/82, etc. This can even include loss of an alkane equivalent (R branch plus H, 16, 30, 44, etc.) to leave behind an alkene cation that can also generate alkene fragments, which is shown later in the notes (McLafferty & allylic). Certain atoms generate characteristic M+2 peak patterns: 35Cl/37Cl = 75/25 ration, 79Br/81Br = 50/50 ratio, 32S/34S = 95/5 ratio. Any peak 1 amu larger than the one in front of it shows about 1% of the front peak for every carbon atom in the formula (e.g. C6 = M+ / M+1 ratio of 100% / 6%).

Spectroscopy Beauchamp 45

A sampling of common and/or miscellaneous peaks that are often seen, (even when they don't make sense). Whatever the initial mass is, a series of masses increased by increments of 14 (CH2)n reveals additional "logical" fragment masses. Remember, we only see the cationic fragments.

R R R CH3 = 15 C R CH3CH2 = 29 H mass = 39 (R = H) C3H7 = 43 C H = 57 53 (R = CH3) mass = 41 (R = H) 4 9 mass = 91 (R = H) C H = 71 67 (R= CH2CH3) 55 (R = CH3) mass = 65 (R = H) 5 11 105 (R = CH ) C H = 85 also works for 69 (R= CH2CH3) 79 (R = CH3) 3 6 13 119 (R= CH CH ) 83 (R=C3H7) 93 (R= CH2CH3) 2 3 R CH2

H R H2N CO O C R H C mass = 29 (R = H) mass = 44 H2 43 (R = CH ) mass = 42 (R = H) 3 H 57 (R= CH2CH3) 56 (R = CH3) mass = 27 mass = 77 RO CO 71 (R = C3H7) 70 (R= CH2CH3) mass = 45 (R = H) 85 (R = C4H9) 84 (R=C3H7) 99 (R = C5H11) 59 (R = CH3) 73 (R = CH CH ) 105 (R = C6H5) 2 3 45 (R= OH) 87 (R = C3H7) Loss of small molecules via elimination reactions. 59 (R= OCH3) HCl HBr 44 (R= NH2) H2O H S CH OH C H OH NH CH CO H HF 2 3 2 5 3 3 2 36 (75%) 80 (50%) mass = 18 34 32 46 17 62 20 38 (25%) 82 (50%) McLafferty Rearrangement Possibilities H R H Notice! O HC McLafferty R O R2 even masses 2 (without N) C = CH2 R R1 1 R CH2 mass = 28 (R = H) R C variable mass, 42 (R = CH ) H2 44 (R = H) 60 (R = OH) 3 58 (R = CH ) 74 (R = OCH ) (can sometimes see this 56 (R= CH2CH3) mass = 3 3 72 (R = CH2CH3) 59 (R = NH2) fragment if it retains the 70 (R = C3H7) 86 (R = C3H7) 78 (R = Cl) cation charge) 84 (R = C4H9)

Similar Patterns - positive charge is written on both fragments to show that either fragment might be seen at the detector H H H CH R H 2 2 R H 2 N R C R2 2 R 1 R R C 1 R C R1 1 H2 C H2 C H H2 2

H H H C H H H 2 R2 H C R2 N R2 R2 C R1 R R CH C R1 C R1 2 R1 CH2 CH2 mass = 42 (R = H) mass = 92 (R = H) mass = 40 (R = H) mass = 41 (R = H) 56 (R = CH3) 106 (R = CH3) 54 (R = CH3) 55 (R = CH3) 70 (R= CH2CH3) 120 (R= CH2CH3) 68 (R= CH2CH3) 69 (R= CH2CH3) 84 (R = C3H7) 134 (R = C3H7) 82 (R = C3H7) 83 (R = C3H7)

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Very Brief Description of Various Mass Spec Techniques – There are other techniques others besides those mentioned below. If you need practical knowledge of the theory and instrumentation of these experimental techniques, you will need to consult specialty references or textbooks.

1. In electron impact (EI), vaporized sample is bombarded with a very high energy beam of electrons at about 70 eV (1600 kcal/mole) knocking an electron out of a bonding orbital, forming a radical cation. EI is relatively inexpensive and additional information can be obtained from fragmentation patterns. However fragmentation can prevent seeing the molecular ion peak (parent peak), which may necessitate using another approach, such as CI (next).

2. Chemical ionization (CI) introduces a reagent gas in the source at higher concentration and the gas is ionized by electrons at 500 eV. The reagent gas acts as a strong acid to protonate a basic site in the molecule of interest (at much lower energy to minimize fragmentation). This adds some mass to the sample, such as +1 (proton) or +(mass of gas). The protonated reagent gas can also abstract a proton (forming M-1). Generally, one can see the molecular mass peak (+1) much more clearly using CI. However, the sample must be vaporized and thermally stable which limits many biological samples or high molecular weight samples. If EI-MS does not produce an M+ peak, we will provide a hypothetical CI mass peak (and always assume it represents M+1). If we have access to a proton and 13C NMR we can use those spectra to provide a proton and carbon count. Both IR and 13C can provide information about the functional groups that are present which will give us a clue about how many oxygen and nitrogen atoms are present. If any larger than expected M+2 peaks show up (molecular ion or in a fragment) we might gain information about chlorine, bromine or sulfur. Using such a combination approach could also lead us to a molecular formula.

3. In fast atom bombardment (FAB), a solution of the sample in a matrix of low volatility is bombarded with neutral fast heavy atoms (Xe, Ar at 7 kev). It is a good method for molecules up to 20 KDa (biological molecules), and one can sequence some proteins. However the matrix usually produces background peaks at nearly every mass. One can usually see ions at M+1 or M-1.

4. In electrospray (ES), a solution of the sample is sprayed at atmospheric pressure through a 2-5 kV potential and the resulting droplets are electrostatically charged. There is no matrix background, multicharged species, molecules up to 200 kDa can be analyzed. However the method is susceptible to contamination of ions in the mist solution and nonpolar molecules are not detected.

5. In matrix assisted laser desorption ionization (MALDI), ions are accelerated to an energy of 3kV for mass analysis. A matrix absorbs energy produced by a laser and there is minimal fragmentation with better resolution than ES and FAB, especially at high mass.

6. In field desorption (FD), a sample is deposited directly onto anode where a high electric field produces desorption and ionization. There are very few fragmentations and is a preferred method for synthetic polymers. However samples may begin to decompose before inserted to the direct inlet. It is not good for high sensitivity and biological samples and has poor reproducibility. Spectroscopy Beauchamp 47

Mass Spec Problem Set Name ______

1. If the molecular ion peak is 142, what molecular formula does the rule of 13 predict if the structure is a hydrocarbon? What formula is predicted if there is one oxygen atom? Two oxygen atoms? Two nitrogen atoms? What is the degree of unsaturation for each possibility above (4 calculations)? Draw one structure for each possibility. What if the molecular ion peak is 143 (same questions)?

+ + + 2. Both CHO and C2H5 have fragment masses of approximately 29, yet CHO has a M+1 peak of 1.13% + and M+2 peak of 0.20%, whereas C2H5 has a M+1 peak of 2.24% and M+2 peak of 0.01%. High + + resolution mass spec shows CHO to have a different fragment mass than C2H5 . Explain these observations and show all of your work. Helpful data follow.

Average Nuclide Element Atomic Mass (Relative Abundance) Mass H 1.00797 1H (100) 1.00783 H 2H (0.016) 2.01410 C 12.01115 12C (100) 12.00000 C 13C (1.08) 13.00336 O 15.9994 16O (100) 15.9949 O 17O (0.04) 16.9991 O 18O (0.20) 17.9992

3. What relative abundance would the characteristic M (let M be 100%), M+2, M+4, M+6 mass peaks have for: (a) tribromo, Br3 substituted alkane, (b) trichloro, Cl3, substituted alkane and (c) bromodichloro, BrCl2 substituted alkane? Show your work. You can use these approximate probabilities (P): P35Cl = 0.75, P37Cl = 0.25, P79Br = 0.50, P81Br = 0.50

4. Radical cations of the following molecules (e- + M  M.+ + 2e-) will fragment to yield the indicated masses as major peaks. The molecular ion peak is given under each structure. The base peak is listed as 100%. Other values listed represent some relatively stable possibilities (hence higher relative abundance), or common fragmentations (expected), even if in low amount. For the fragments with arrows pointing at them, show what the fragment is and how it could form from the parent ion. This may be as easy as drawing a line between two atoms of a bond, or it may require drawing curved arrows to show how electrons move (e.g. McLafferty). Explain why each fragment is reasonable. This may involve drawing o + o + o + + resonance structures or indicating special substitution patterns (3 R > 2 R > 1 R > CH3 ). If a fragment has an even mass and there is a pi bond, think McLafferty (unless an odd number of nitrogen atoms are present). Even masses can also be formed by elimination of a small molecule such as loss of water from an alcohol or loss of an alcohol from an ether or a retro-Diels-Alder reaction, etc. Make sure you show this.

Peaks with arrows are expected from the functional group shown. Most of the other peaks should be explainable using the examples in the prior discussions. See how many you can explain.

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m/e % base m/e % base b. a. H H H 27.0 20.1 27.0 17.2 2 2 2 C C C CH3 29.0 27.4 CH3 29.0 33.6 H3C C C C 41.0 43.8 H C 41.0 49.1 H2 H2 H2 42.0 15.3 3 42.0 5.6 C CH3 + 43.0 100.0 43.0 100.0 M = 114 55.0 11.4 H3C C 55.0 11.3 H2 56.0 18.4 56.0 28.0 57.0 33.5 M+ = 86 57.0 98.3 Is there a logical peak that is missing? 70.0 12.1 71.0 76.7 71.0 20.4 72.0 4.5 85.0 26.5 86.0 <1.0 114.0 6.0

c. m/e % base 27.0 10.0 41.0 49.5 H No easy explanation for 42.0 24.7 ? 43.0 11.2 56, but if ring opens and 56.0 100.0 forms alkene, McLafferty M+ = 84 69.0 35.4 might work. 84.0 17.5

d. e. m/e % base m/e % base 27.0 32.9 CH H2 29.0 24.4 27.0 20.8 C C 39.0 54.9 40.0 61.2 41.0 68.2 H3C C 42.0 31.4 H2 41.0 22.7 M+ = 84 43.0 100.0 + 42.0 22.3 56.0 49.8 M = 68 53.0 44.0 69.0 16.9 67.0 100.0 You might have to 84.0 11.7 68.0 15.3 move the C=C around. Don't remove the sp C-H, there is a better spot to lose an H atom (resonance).

f. g. m/e % base H2 27.0 32.7 C CH H2 H2 3 m/e % base C C 29.0 16.1 C 31.0 83.4 H2 H3C C OH 65.0 7.2 H2 41.0 65.6 77.0 2.7 + 42.0 31.6 M+ = 120 91.0 100.0 M = 74 43.0 59.3 92.0 10.8 56 is an even mass, but not 55.0 14.1 105.0 3.8 McLafferty. A small molecule 56.0 100.0 Use a bridging ring to make 105. 120.0 25.9 might help explain it. 57.0 5.9 74.0 <1.0

Spectroscopy Beauchamp 49

h. m/e % base i. m/e % base OH 27.0 9.8 27.0 23.0 H2 28.0 7.9 CH CH 28.0 51.5 C O CH3 3 29.0 6.0 29.0 34.9 H3C C H3C C C 31.0 100.0 H 31.0 16.8 H2 H2 2 41.0 11.7 42.0 4.1 M+ = 74 43.0 9.2 M+ = 88 43.0 39.8 45.0 100.0 59.0 98.3 56.0 1.5 73.0 3.3 Peak 31 is harder to 88.0 25.7 explain, but common. 59.0 20.5 74.0 <1.0 28 and 42 are even, but not McLafferty. Think like "g", but "organic" water. 31 requires some drastic rearrangements.

j. k. O H2 H2 m/e % base C C H2 m/e % base C C CH 27.0 8.2 H3C C NH2 3 H2 29.0 14.8 27.0 3.5 H3C C C + H2 H2 43.0 100.0 M = 73 29.0 2.1 57.0 15.8 30.0 100.0 M+ = 100 58.0 49.8 43.0 1.2 Peak 30 dominates. Think of a 85.0 6.4 56.0 1.2 small molecule elimination for 43 is different than C H + 100.0 8.0 peak 56. 73.0 7.3 3 7

l. O m. m/e % base m/e % base O H2 27.0 47.0 C C 27.0 73.5 H2 29.0 9.2 H3C C C H C CH3 29.0 54.8 41.0 45.3 H O C CH3 2 41.0 69.1 H 43.0 100.0 43.0 75.3 2 M+ = 72 M+ = 102 59.0 22.2 44.0 100.0 71.0 49.9 + 57.0 23.3 74.0 64.2 29 is different than C2H5 72.0 53.6 74 is an even mass. 87.0 16.4 44 is an even mass, so... 102.0 1.4

o. n. O m/e % base O m/e % base H2 27.0 26.6 H2 C C 27.0 13.6 C C 29.0 26.1 29.0 8.1 41.0 53.4 H2N C CH3 HO C CH3 H2 43.0 32.2 H2 41.0 16.3 43.0 14.1 + 44.0 66.3 M+ = 88 45.0 9.9 M = 87 59.0 100.0 60.0 100.0 71.0 8.0 An even mass strikes again 73.0 32.5 Normally 59 would be even, 72.0 19.2 at 60 and 45 is not common, 88.0 2.6 87.0 2.9 but expected here. but there is nitrogen present.

p. q. m/e % base m/e % base N H2 C C 27.0 28.6 27.0 9.3 41.0 19.3 C CH3 29.0 66.3 H2 40.0 3.8 68.0 100.0 91.0 12.7 M+ = 69 41.0 100.0 42.0 4.0 92.0 18.8 Normally 41 would be even, 54.0 1.2 M+ = 136 95.0 7.6 but there is nitrogen present. 69.0 0.2 121.0 19.5 Two famous names goes with 68. 136.0 22.6

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Problem 11 – On the following pages are 22 compounds (these are lettered A-V) from the 22 functional groups numbered below. Try to match each spectrum (A-V) to the class of functional group numbered 1-22, and then try to solve the exact structure of each compound. These are simple monofunctional group compounds. Explain the major peaks that helped decide on your structure. Why are these peaks formed in preference to others (what is the reason for their special stability)?

Classes of compounds

1. alkane 2. branched alkane 3. cycloalkane 4. alkene 5. alkyne 6. aromatic 7. fluorinated alkane 8. chlorinated alkane 9. brominated alkane 10. iodinated alkane 11. alcohol 12. ether 13. phenol 14. aldehyde 15. ketone 16. ester 17. acid 18. amine 19. amide 20. acid chloride 21. sulfide 22. thiol

A few hints are given with some of the spectra to help you match structures with the functional groups mentioned above. The mass of each peak is listed with its percent of the base peak. The IR spectra should also give you some functional group hints. Remember, not every wave number is interpretable.

Sample A answer (remove) oct-1-yne Major peaks mass percent Mass Spec - Only larger and/or significant peaks are shown. Hint: No N or O. Explain peaks at 67, 53 and 39. Peak 54 associated with McLafferty. 26 3 28 5 %T 29 6 39 36 100 40 25 41 64 725 42 16 2120 1375 43 49 1385 50 6 50 51 8 3310 1470 52 4 53 15 54 27 2960-2850 650 55 3 0 65 5 3500 30002500 2000 1500 1000 500 67 100 (base) 4000 68 6  = wavenumber = cm-1 81 10 82 = M+ 100% 67 = base peak

75% 41

50% 43 39 40 54 42 M+ peak = 82 25% 53 (very small) 81 0%

20 30 40 50 60 70 80 90 100 110 m/e

Spectroscopy Beauchamp 51

Sample B Major peaks 1-methylcyclohexene (remove) MW = 96 mass percent Mass Spec - Only larger and/or significant peaks are shown. Hint: Strong M+ peak, easily lost branch explains 81 and two famous names are associated with 68. 27 6 29 4 %T 39 12 40 4 100 41 11 53 13 54 16 1685 1375 55 28 1385 838 65 4 50 67 42 1470 68 36 77 5 79 11 2960-2850 81 100 (base) 0 82 7 3500 30002500 2000 1500 1000 500 95 8 4000 96 41 = M+  = wavenumber = cm-1 97 4

100% 81 = base peak

75%

50% 67 M+ = 96 55 68 25% 39 41 54 53 79 0% 20 30 50 70 40 60 m 80 90 100 110 e Major peaks Major peaks Sample C 4-methyl-1-bromopentane mass percent mass percent MW = 164 (remove in book) Mass Spec - Only larger and/or significant peaks are shown. 15.0 1 85.0 59 Hint: (M+2) is helpful, as are 151/149, 109/107. Explain 85, 57 and 43. 27.0 13 86.0 4 28.0 1 107.0 3 %T 29.0 8 109.0 2 38.0 1 149.0 3 100 39.0 11 151.0 3 40.0 2 164.0 2 = M+ 41.0 44 166.0 2 = M+2 42.0 42 1385 50 43.0 100 (base) 1470 640 560 44.0 3 1250 53.0 2 55.0 5 2960-2850 56.0 12 57.0 9 0 69.0 31 4000 3500 30002500 2000 1500 1000 500 70.0 2 -1 83.0 1  = wavenumber = cm 84.0 2

100% 43 = base peak

75% 85 41 50% 42 69

25% 56 107 57 149 164 = M+ 109 151 166 = M+2 0% 20 40 80 60 100 m 120 140 160 180 200 e

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Sample D p-thiomethyltoluene Major peaks Major peaks MW = 138 (remove in book) mass percent Mass Spec - Only larger and/or significant peaks are shown. mass percent 106.0 10 Hint: (M+2) is helpful. There is no major peak at 91 for a reason, but 105 will substitute. 27.0 3 39.0 4 135.0 2 %T 45.0 6 137.0 2 50.0 2 138.0 15.5 = M+ 100 51.0 4 139.0 2 52.0 1 140.0 0.9 = M+2 (5.8%) 3050 53.0 2 1375 63.0 2 3550 1385 65.0 3 50 68.0 2 1520 1440 77.0 11 78.0 4 79.0 11 2960-2850 820 89.0 1 0 91.0 5 3500 30002500 2000 1000 500 93.0 1 4000 1500 103.0 8  = wavenumber = cm-1 104.0 6 105.0 100 (base) 100% 105 = base peak

75%

50%

25% 138 = M+ 77 79 140 = M+2 0% 20 40 80 60 100 m 120 140 160 180 200 e

Sample E butoxybenzene Major peaks Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 150 (remove in book) mass percent mass percent Hint: McLafferty can explain 94, though there is no carbonyl group, but there is an xygen. 107 is 27.0 4.1 small, but more like what you would expect for this functional group. Regular peaks at 29 and 57. 29.0 11.2 %T The IR peak at 1220 is important. 39.0 7.1 40.0 1.4 100 41.0 8.3 50.0 1.2 3040 51.0 4.4 55.0 1.5 1380 56.0 1.1 50 57.0 3.9 63.0 1.1 65.0 5.3 2960-2850 1600 1500 1250 760 690 66.0 5.5 77.0 7.4 0 94.0 100.0 (base) 4000 3500 30002500 2000 1500 1000 500 95.0 7.0  = wavenumber = cm-1 107.0 1.6 150.0 18.4 = M+ 151.0 2.1 100% 94 = base peak

75%

50%

25% 150 = M+ 57 69 29 41 77 107 0% 20 40 80 60 100 m 120 140 160 180 200 e

Spectroscopy Beauchamp 53

Sample F propylbenzene Major peaks Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 120 (remove in book) mass percent mass percent Hint: The big base peak is a big clue. 27.0 2 39.0 4 %T 41.0 2 50.0 1 100 51.0 4 63.0 2 65.0 7 3030 1610 77.0 3 50 78.0 6 1500 79.0 1 89.0 1 91.0 100 (base) 2960-2850 1450 740 700 92.0 12 0 103.0 1 3500 30002500 2000 1000 500 105.0 4 4000 1500 120.0 26 = M+  = wavenumber = cm-1 121.0 3

100% 91 = base peak

75%

50% 120 = M+ 25% 41 65 103 29 78 105 0% 20 40 80 60 100 m 120 140 160 180 200 e

Major peaks Major peaks Sample G octan-3-one Mass Spec - Only larger and/or significant peaks are shown. MW = 128 (remove in book) mass percent mass percent Hint: There are a lot of peaks that could be explained, both large and small. 15.0 1 72.0 67 Try 100, 86, 85, 71, 57, 43 and 29. McLafferty might help on some of these. 18.0 1 73.0 8 %T 26.0 2 81.0 1 27.0 21 85.0 10 100 28.0 4 86.0 3 29.0 58 99.0 52 3420 30.0 1 100.0 4 39.0 8 128.0 12 = M+ 40.0 1 129.0 1 50 41.0 17 1460 1410 1380 42.0 4 43.0 100 (base) 44.0 4 2960-2850 1720 53.0 2 0 55.0 9 3500 30002500 2000 1500 1000 500 56.0 3 4000 57.0 92  = wavenumber = cm-1 58.0 5 71.0 52 43 = base peak 57 72 29 71 99 50%

25% 85 128 = M+ 0% 20 40 80 60 100 m 120 140 160 180 200 e

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Major peaks Sample H 2-ethylhexanal Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 128 (remove in book) mass percent mass percent Hint: There are a lot of peaks that could be explained, both large and small. Try 100, 72, 27.0 15 71.0 5 57, 43 and 29. McLafferty might help on some of these. 28.0 1 72.0 100 (base) %T 29.0 24 73.0 5 39.0 9 81.0 1 100 40.0 1 82.0 3 41.0 34 85.0 3 3420 2810 42.0 4 100.0 1 2700 43.0 40 128.0 1 = M+ 44.0 2 50 1340 53.0 2 1460 54.0 3 55.0 11 56.0 4 2960-2850 1730 57.0 82 0 58.0 4 3500 30002500 2000 1500 1000 500 67.0 2 4000 68.0 1  = wavenumber = cm-1 69.0 2 70.0 1 100% 57 72 = base peak

75%

50% 41 43

25% 27 29 55 15 128 = M+ 0% 20 40 80 180 200 60 100 m 120 140 160 e

Major peaks Sample I pentylamine Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 87 (remove in book) mass percent mass percent 18.0 2 Hint: Notice the odd mass peak and the really big peak at 30. Though small 29 and 43 are obvious. 27.0 3 %T 28.0 33 29.0 2 100 30.0 100 (base) 31.0 2 39.0 2 3370 41.0 3 3290 1610 42.0 2 50 1380 43.0 1 1470 44.0 2 820 45.0 3 87.0 4 = M+ 2960-2850 0 4000 3500 30002500 2000 1500 1000 500  = wavenumber = cm-1

30 = base peak

50% 27

25% 87 = M+ 0% 20 40 80 60 100 m 120 140 160 180 200 e

Spectroscopy Beauchamp 55

Major peaks Sample J heptane Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 100 (remove in book) mass percent mass percent Hint: Look how regular the peaks are. What is lost in each fragment…100, 85, 71, 57, 43, 29? 15.0 1 72.0 2 26.0 1 85.0 2 %T 27.0 18 100.0 11 = M+ 28.0 3 100 29.0 31 39.0 11 40.0 2 41.0 45 42.0 20 50 1380 720 1470 43.0 100 (base) 44.0 3 53.0 1 55.0 10 2960-2850 56.0 25 0 57.0 47 3500 30002500 2000 1500 1000 500 58.0 2 4000 70.0 18  = wavenumber = cm-1 71.0 46

43 = base peak 57

99 41 50% 42 29 71 56 25% 70 100 = M+ 72 85 0% 20 40 80 60 100 m 120 140 160 180 200 e

Major peaks Sample K 2-ethylpentane Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 100 (remove in book) mass percent mass percent 27.0 10 Hint: You can barely see the M+ peak because…? 43 is big and 71, 57 and 29 are all there too. 29.0 14 %T 39.0 6 41.0 16 100 42.0 7 43.0 100 (base) 44.0 4 53.0 1 1380 770 55.0 15 50 56.0 4 1460 890 57.0 4 70.0 48 71.0 51 2960-2850 72.0 3 0 100.0 2 = M+ 4000 3500 30002500 2000 1500 1000 500  = wavenumber = cm-1

43 = base peak

41 50% 42 70 71

25% 29 27 55 57 72 100 = M+ 0% 20 40 60 80 100 160 180 200 m 120 140 e

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Major peaks Major peaks Sample L dipropylsulfide Mass Spec - Only larger and/or significant peaks are shown. MW = 118 (remove in book) mass percent mass percent 15.0 2 Hint: The (M+2) at 120 is helpful, as are 103, 89, 43 and 29. Why is 89 so big and 103 so small? 27.0 25 %T 29.0 6 39.0 16 100 41.0 2 42.0 65 43.0 100 (base) 47.0 47 1380 61.0 35 50 75.0 13 76.0 50 89.0 92 103.0 4 2960-2850 1470 118.0 63 = M+ 0 119.0 5 4000 3500 30002500 2000 1500 1000 500 120.0 3 = M+2 (4.8%)  = wavenumber = cm-1

43 = base peak 89

42 118 = M+ 47 76 50% 61 27 25% 75 29 103 120 = M+2 (4.8%) 0% 20 40 60 80 100 160 180 200 m 120 140 e

Major peaks Sample M 1-iodohexane Major peaks Mass Spec - Only larger and/or significant peaks are shown. MW = 212 (remove in book) mass percent mass percent Hint: Look at that big hole in the middle…then there's 85, 57, 43, 29. 27.0 14 28.0 4 %T 29.0 15 39.0 7 100 40.0 1 41.0 25 42.0 3 1370 43.0 100 (base) 1420 44.0 3 50 53.0 1 55.0 6 56.0 2 57.0 11 2960-2850 1460 85.0 50 0 86.0 3 4000 3500 30002500 2000 1500 1000 500 155.0 2 212.0 4 = M+  = wavenumber = cm-1

43 = base peak

85 50%

25% 29 57 86 155 212 = M+ 0% 20 40 60 80 100 160 180 200 m 120 140 e

Spectroscopy Beauchamp 57

Sample N Major peaks Major peaks hexan-1-ol mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 102 (remove in book) 15.0 1 84.0 9 Hint: If you look hard there is a tiny peak at 102 (=M+)…and then a gap of 18. Some 18.0 3 102.0 0 M+ (missing) familiar peaks at 57, 43 and 29 are helpful. There's a special reason that 31 is there…why? 27.0 15 %T 28.0 3 29.0 20 100 31.0 24 39.0 8 41.0 36 1380 660 42.0 43 50 43.0 59 45.0 3 3320 53.0 2 55.0 49 2960-2850 1470 1060 56.0 100 57.0 7 0 69.0 25 4000 3500 30002500 2000 1500 1000 500 70.0 3  = wavenumber = cm-1 71.0 2 73.0 1 83.0 2 56 = base peak

43 55 50% 42 31 41 69 25% 29 27 70 84 M+ = 102 15 71 is missing 0%

20 40 60 80 m 100 120 140 160 180 200 e

Sample O Major peaks Major peaks hexanoic acid (remove in book) mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 144 15.0 1 73.0 92 Hint: 144 is tiny, but important. (M-56) is big for a reason (McLafferty). Other helpful 18.0 4 74.0 5 peaks are 73, 71, 57, 56, 45, 43, 29. 29.0 22 87.0 21 %T 31.0 1 88.0 100 (base) 100 39.0 10 89.0 5 41.0 32 101.0 18 42.0 5 115.0 11 3300-2500 43.0 20 116.0 14 45.0 7 144.0 0.5 = M+ 50 1380 53.0 2 55.0 17 1460 56.0 5 57.0 38 2864 59.0 3 2925 1710 1230 940 60.0 2 0 69.0 6 4000 3500 30002500 2000 1500 1000 500 70.0 4  = wavenumber = cm-1 71.0 1

73 88 = base peak M+ = 102 is missing

50% 57 41 55 43 87 101 115 25% 29 56 116 45 70 31 71 144 = M+ 0%

20 40 60 80 m 100 120 140 160 180 200 e

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Sample P propyl pentanoate Major peaks Major peaks mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 144 (remove in book) 15.0 2 86.0 6 Hint:. McLafferty can occur two ways, at 116 and 88. Other useful peaks are at 57, 43, 29 27.0 24 87.0 3 and 45 is there for a reason. By the way, the M+ peak is missing at 144 28.0 8 102.0 10 %T 29.0 29 103.0 60 31.0 4 100 104.0 4 39.0 10 115.0 4 41.0 38 42.0 19 M+ = 144 43.0 40 is missing 1380 55.0 7 50 56.0 5 1460 1250 1090 57.0 57 59.0 7 60.0 34 2850-2960 1740 1180 61.0 29 0 73.0 19 4000 3500 3000 2500 2000 1500 1000 500 84.0 1  = wavenumber = cm-1 85.0 100 (base)

85 = base peak

103 57 60 50% 40 43 61 29 41 27 73 25% 104 115 15 M+ = 144 31 is missing 0%

20 40 60 80 m 100 120 140 160 180 200 e

Sample Q Major peaks Major peaks heptanamide mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 143 (remove in book) 18.0 2 . 73.0 6 Hint: Has an odd M+ peak at 143. McLafferty can explain the base peak at 59 and other 27.0 5 82.0 2 familiar peaks are 43 and 29. The peak at 44 can be explained too. 28.0 2 83.0 2 %T 29.0 7 84.0 1 100 39.0 4 86.0 10 41.0 13 96.0 1 42.0 4 97.0 1 43.0 16 100.0 6 44.0 19 114.0 5 50 1460 640 53.0 1 143.0 6 = M+ 54.0 1 3190 1380 720 55.0 8 56.0 2 3360 2850-2960 57.0 10 1650 1630 59.0 100 (base) 0 60.0 7 4000 3500 3000 2500 2000 1500 1000 500 69.0 2  = wavenumber = cm-1 72.0 34

59 = base peak

50% 72 43 25% 4144 55 29 100 M+ = 143 18 42 57 0%

20 40 60 80 m 100 120 140 160 180 200 e

Spectroscopy Beauchamp 59

Sample R Major peaks Major peaks 1-octene (remove in book) mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 112 15.0 1 .Hint: Some important peaks are M+ at 112 and 41 has a special reason as does 56 27.0 25 (McLafferty-like, but there is no oxygen). Other familiar peaks are at 71, 57, 43 and 29. 28.0 5 %T 29.0 35 39.0 28 100 41.0 82 42.0 66 43.0 100 (base) 53.0 8 3080 1640 1380 50 990 55.0 99 1470 56.0 87 910 57.0 19 69.0 44 70.0 86 2850-2960 71.0 12 0 83.0 34 4000 3500 3000 2500 2000 1500 1000 500 84.0 22  = wavenumber = cm-1 85.0 2 112.0 20 = M+ 43 = base peak 55 41 70 42 56

50% 69 29 83 27 39 M+ = 112 25% 57 84 53 71 15 85 0%

20 40 60 80 m 100 120 140 160 180 200 e

Sample S Major peaks Major peaks p-ethylphenol mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 122 (remove in book) 27.0 3 103.0 2 . Hint: The M+ peak is solid at 122…and look at that peak at 107 (think "91" plus a really 38.0 1 107.0 100 (base) good something extra). That's almost all there is. 39.0 6 108.0 8 %T 41.0 1 121.0 3 50.0 2 122.0 36 = M+ 100 51.0 4 123.0 3 52.0 2 53.0 2 55.0 2 3020 50 62.0 1 63.0 2 3330 1620 1450 65.0 3 77.0 13 78.0 3 2850-2960 1510 1240 830 79.0 2 0 91.0 4 4000 3500 3000 2500 2000 1500 1000 500 94.0 1  = wavenumber = cm-1

107 = base peak

50% M+ = 122

25% 77 39 108 27 55 65 91 121 0%

20 40 60 80 m 100 120 140 160 180 200 e

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Sample T 1-chloropentane Major peaks Major peaks mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 106 (remove in book) 15.0 1 Hint:. The M+ peak barely shows at 106 (and 108 is 1/3 its size). 70 is really big because 27.0 27 it lost a small molecule of… (36)? 71, 57, 43 and 29 are old familiar friends. 28.0 6 %T 29.0 38 100 39.0 19 41.0 70 42.0 100 (base) 43.0 39 53.0 3 50 55.0 93 56.0 6 1350 57.0 22 63.0 5 2850-2960 1470 750 660 69.0 3 70.0 95 0 71.0 6 4000 3500 3000 2500 2000 1500 1000 500 91.0 3  = wavenumber = cm-1 93.0 0.9 106.0 1.0 = M+ 108.0 0.3 = M+2 42 = base peak 70 55

50% 29 43 27 25% 39 57 91 M+ = 106 15 93 M+2 = 108 0%

20 40 60 80 m 100 120 140 160 180 200 e

Sample U Major peaks Major peaks benzylfluoride mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 110 (remove in book) 27.0 2 91.0 8 .Hint: M+ is big, but M-1 is bigger and that's unusual. However, it has lots of stabilization. 28.0 2 92.0 1 There is a halogen present, but M+2 is not important. What does 91 remind you of? 31.0 1 107.0 2 %T 39.0 8 108.0 1 100 44.0 1 109.0 100 (base) 45.0 2 110.0 55 = M+ 50.0 5 111.0 4 51.0 8 1510 57.0 5 50 62.0 3 3080-3030 63.0 6 1470 1380 65.0 4 2850-2960 77.0 2 740 700 81.0 2 980 83.0 12 0 89.0 4 4000 3500 3000 2500 2000 1500 1000 500  = wavenumber = cm-1

109 = base peak

110 = M+ 50%

25% 27 44 51 83 91 29 31 39 45 57 65 77 0%

20 40 60 80 m 100 120 140 160 180 200 e

Spectroscopy Beauchamp 61

Major peaks Major peaks Sample V benzoyl choride (remove in book) mass percent mass percent Mass Spec - Only larger and/or significant peaks are shown. MW = 134.6 15.0 4 80.0 11 . Hint: Peaks at 105 and 106 have M+2 about 1/3 their size. There is a really helpful 27.0 59 91.0 12 band in the IR spectrum. There are the usual peaks at 29, 43, 57 and 71. 29.0 44 92.0 1 %T 39.0 36 98.0 24 41.0 84 99.0 84 100 42.0 43 105.0 6 43.0 97 106.0 6 53.0 5 107.0 2 = mass+2 55.0 100 (base) 108.0 2 = mass+2 56.0 27 1380 50 57.0 45 134.0 0 M+ 1470 1130 580 440 60.0 13 (missing) 65.0 2 69.0 10 2860-2960 1800 960 730 70.0 23 0 71.0 40 4000 3500 3000 2500 2000 1500 1000 500 77.0 4  = wavenumber = cm-1 78.0 34

41 43 55 = base peak 42 99

27 50% 29 39 56 71 78 57 105 70 106 25% 107 60 69 91 15 80 108 134.0 0 M+ 53 65 (missing) 0%

20 40 60 80 m 100 120 140 160 180 200 e

What Happens When There is More Than One Functional Group?

We have mostly looked at monofunctional groups to learn the main clues provided by each functional group toward our goal of determining organic structures. What if more than one functional group is present? We can pit two strongly stabilizing groups against one another and see what happens. Both benzyl (91 mass) and methyliminium (30 mass) carbocations are strongly stabilized and generate easily recognizable MS peaks. We have seen both individually earlier, but we will repeat them below for comparison.

27.0 2 15.0 1 39.0 4 18.0 3 41.0 2 26.0 1 H 50.0 1 27.0 4 51.0 4 28.0 8 CH 2 63.0 2 29.0 2 65.0 7 H 30.0 100.0 base 77.0 3 NH 2 31.0 2 peak 78.0 6 H2C 39.0 2 79.0 1 41.0 5 H2N 89.0 1 base 42.0 3 mass = 91 91.0 100 peak M+ = 59 mass = 30 43.0 2 M+ = 120 92.0 11 (M-29) 44.0 1 (M-29) 103.0 1 56.0 1 105.0 4 58.0 2 120.0 26 59.0 9

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One way we could pit these two groups against one another would be to look at the mass spectrum of benzyl amine. Do we lose the amine group, NH2, or do we lose the phenyl group, C6H5? Not surprisingly, we don’t lose either. Instead they work together to make an even more stable carbocation with mass of 106 (M-1).

27.0 2 74.0 2 H H H 28.0 11 75.0 1 29.0 5 76.0 2 30.0 27 77.0 19 CH2 NH 32.0 1 78.0 12 2 NH2 NH2 38.0 2 79.0 35 H C 39.0 6 80.0 3 2 41.0 1 89.0 4 50.0 6 90.0 2 M+ = 107 51.0 11 91.0 15 mass = 106 (100%) mass = 91 (15%) mass = 30 (27%) 52.0 4 92.0 2 (M-29) (M-16) (M-77) 52.5 2 103.0 2 both 53.0 3 104.0 5 benzyl 62.0 1 stabilizing carbocation 105.0 1 base imminium 63.0 3 106.0 100 groups (tropylium ion) ion peak 65.0 5 107.0 60

Another way to compare these two groups would be to look at the spectrum of 2-phenylethylamine (phenethylamine). Do we lose benzyl or do we lose methylimminium? Here we find the methylimminium group is the preferred method of fragmentation, but the benzyl carbocation is still observable. As molecules get more complicated, so will their mass spectra. We will not emphasize such examples because there are other methods much more helpful to our goal of determining organic structures, namely 1H and 13C NMR spectroscopy. 28.0 2 H 30.0 100 base H 31.0 1 peak CH2 39.0 3 NH2 NH 50.0 1 2 NH2 51.0 3 H2C 63.0 2 H 65.0 6 mass = 30 (100%) H 77.0 2 mass = 30 (15%) 89.0 1 M+ = 121 91.0 15 (M-29) (M-91) mass = 120 (1%) 92.0 6 benzyl imminium (M-1) 103.0 2 carbocation ion 120.0 1 (tropylium ion) 121.0 6 Problem – Discuss the MS of the following compounds. How do they compare to those in the examples above? 15.0 1 27.0 2 26.0 2 39.0 4 27.0 10 41.0 2 28.0 4 50.0 1 29.0 7 51.0 4 30.0 2 63.0 2 31.0 100 base 65.0 7 32.0 2 peak 77.0 3 33.0 1 78.0 6 HO 39.0 4 79.0 1 41.0 7 89.0 1 base 42.0 12 91.0 100 M+ = 60 M+ = 120 peak 43.0 2 92.0 11 45.0 2 103.0 1 57.0 1 105.0 4 59.0 16 120.0 26 60.0 10

18.0 1 50.0 10 76.0 2 27.0 1 74.0 1 26.0 1 51.0 21 77.0 49 31.0 4 77.0 5 27.0 6 52.0 6 78.0 11 base 38.0 1 78.0 4 28.0 2 53.0 6 79.0 100 39.0 8 OH peak OH 79.0 1 29.0 4 53.5 2 80.0 10 (very 41.0 1 89.0 3 31.0 3 54.0 1 89.0 6 unusual) 50.0 3 90.0 1 37.0 2 61.0 1 90.0 9 51.0 6 91.0 100 base 38.0 3 62.0 3 91.0 17 52.0 2 92.0 60 peak 39.0 11 63.0 6 92.0 2 62.0 1 93.0 4 M+ = 108 40.0 1 64.0 2 105.0 4 63.0 4 103.0 4 41.0 1 65.0 7 107.0 68 M+ = 122 64.0 1 104.0 4 43.0 1 74.0 3 108.0 99 65.0 15 122.0 30 49.0 1 75.0 2 109.0 8 66.0 1 123.0 3 Spectroscopy Beauchamp 63

Problem – Major peaks in mass spectra representing most organic groups are provided below. Explain as many peaks as seems reasonable. There is plenty of opportunity to practice your new mass spec skills.

Alkanes (Also look for alkene fragments too.)

mass % mass % mass % mass % mass % 27.0 19 44.0 3 72.0 3 28.0 3 53.0 2 85.0 2 29.0 31 55.0 10 100.0 11 39.0 11 56.0 25 C7H16 40.0 2 57.0 48 M+ = 100 41.0 45 58.0 2 42.0 20 70.0 18 heptane 43.0 100 71.0 46

mass % mass % mass % mass % mass % 27.0 11 53.0 1 84.0 5 29.0 15 55.0 5 85.0 37 39.0 8 56.0 21 86.0 3 40.0 1 57.0 29 100.0 3 41.0 31 C H 58.0 1 7 16 42.0 35 69.0 1 M+ = 100 43.0 100 70.0 2 2-methylhexane 44.0 3 71.0 2

mass % mass % mass % mass % mass % 27.0 12.8 53.0 1.8 72.0 3.1 29.0 24.7 55.0 15.0 84.0 1.1 39.0 9.1 56.0 39.3 85.0 5.7 40.0 1.5 57.0 52.8 100.0 4.0 C H 41.0 36.7 58.0 2.3 7 16 42.0 9.2 M+ = 100 69.0 2.0 43.0 100.0 70.0 46.5 3-methylhexane 44.0 3.5 71.0 58.3 mass % mass % mass % mass % mass % 27.0 9.9 55.0 14.9 29.0 14.3 56.0 3.6 39.0 6.4 57.0 4.5 41.0 16.1 70.0 48.4 C H 42.0 6.8 71.0 50.6 7 16 43.0 100.0 M+ = 100 72.0 2.8 44.0 3.5 100.0 1.7 3-ethylpentane 53.0 1.4 mass % mass % mass % mass % mass % 27.0 14.8 44.0 3.4 71.0 38.2 28.0 1.3 53.0 2.2 72.0 2.2 29.0 27.0 55.0 9.8 84.0 1.0 39.0 10.8 56.0 99.8 85.0 12.6 C7H16 40.0 2.0 57.0 76.2 100.0 3.0 M+ = 100 41.0 52.5 58.0 3.3 42.0 26.0 69.0 1.9 2,3-dimethylpentane 43.0 100.0 70.0 10.8 mass % mass % mass % mass % mass % 27.0 9.3 55.0 11.2 86.0 1.3 29.0 11.5 56.0 1.3 100.0 0.0 39.0 6.4 57.0 6.1 41.0 15.7 69.0 1.4 C7H16 42.0 2.7 70.0 18.0 M+ = 100 43.0 100.0 71.0 69.7 44.0 3.4 72.0 4.1 3,3-dimethylpentane 53.0 1.8 85.0 19.3

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mass % mass % mass % mass % mass % 15.0 1.0 44.0 3.3 85.0 18.5 27.0 10.6 53.0 1.0 86.0 1.3 29.0 14.0 55.0 3.2 100.0 0.0 39.0 7.6 56.0 35.3 40.0 1.4 57.0 71.7 C7H16 M+ = 100 41.0 33.5 58.0 3.2 42.0 23.9 69.0 2.4 2,4-dimethylpentane 43.0 100.0 71.0 1.1

mass % mass % mass % mass % mass % 15.0 1.5 44.0 2.1 83.0 1.0 27.0 8.4 53.0 1.6 85.0 34.4 29.0 15.6 55.0 5.1 86.0 2.3 39.0 9.3 56.0 58.3 100.0 0.0 C7H16 40.0 1.6 57.0 100.0 M+ = 100 41.0 42.1 58.0 4.6 42.0 2.7 59.0 2.8 2,2,3-trimethylbutane 43.0 62.6 69.0 2.4

mass % mass % mass % mass % mass % 15.0 1.3 40.0 3.1 55.0 12.1 86.0 10.0 26.0 1.7 41.0 72.5 56.0 70.5 27.0 22.7 42.0 42.4 57.0 100.0 28.0 4.7 43.0 80.9 58.0 4.7 29.0 42.5 44.0 2.8 69.0 8.5 C6H14 30.0 1.0 51.0 1.2 70.0 2.6 M+ = 86 38.0 1.2 53.0 2.2 71.0 11.0 hexane 39.0 14.8 54.0 1.2 84.0 3.2 mass % mass % mass % mass % mass % 27.0 12.6 44.0 3.2 72.0 2.2 28.0 1.3 53.0 1.2 78.0 1.0 29.0 11.3 55.0 6.7 85.0 1.5 39.0 9.6 56.0 9.4 86.0 6.1 40.0 1.5 57.0 17.0 C6H14 41.0 29.5 69.0 1.3 M+ = 86 42.0 52.6 70.0 10.2 2-methylpentane 43.0 100.0 71.0 39.5 mass % mass % mass % mass % mass % 26.0 1.0 43.0 25.4 86.0 3.0 27.0 13.3 53.0 1.8 28.0 2.2 55.0 6.7 29.0 39.1 56.0 76.7 39.0 9.2 57.0 100.0 C6H14 40.0 1.2 58.0 4.5 M+ = 86 41.0 53.4 70.0 1.6 3-methylpentane 42.0 3.6 71.0 5.7 mass % mass % mass % mass % mass % 15.0 1.6 41.0 49.1 57.0 98.3 26.0 1.1 42.0 5.6 58.0 4.7 27.0 17.2 43.0 100.0 70.0 3.3 28.0 2.6 44.0 3.1 71.0 76.7 29.0 33.6 51.0 1.1 72.0 4.5 C6H14 38.0 1.0 53.0 2.5 86.0 0.1 M+ = 86 39.0 13.6 55.0 11.3 2,2-dimethylbutane 40.0 1.8 56.0 28.0 mass % mass % mass % mass % mass % 15.0 1.4 43.0 100.0 86.0 3.6 27.0 13.7 44.0 3.5 28.0 1.9 53.0 1.4 29.0 7.5 55.0 5.2 39.0 9.0 56.0 1.5 C6H14 M+ = 86 40.0 1.5 57.0 2.3 41.0 27.4 71.0 19.2 2,3-dimethylbutane 42.0 87.0 72.0 1.1

Spectroscopy Beauchamp 65

Alkenes & Cycloalkanes

mass % mass % mass % mass % mass % 15.0 1.1 39.0 30.5 53.0 6.5 69.0 31.1 18.0 1.2 40.0 4.9 54.0 7.6 70.0 44.2 26.0 2.0 41.0 96.8 55.0 67.6 71.0 2.5 27.0 25.7 42.0 54.9 56.0 100.0 83.0 4.2 C H 28.0 4.9 43.0 15.9 57.0 30.7 98.0 13.8 7 14 99.0 1.1 M+ = 98 29.0 55.9 50.0 1.5 58.0 1.3 30.0 1.2 51.0 2.3 67.0 2.3 1-heptene 38.0 1.8 52.0 1.0 68.0 3.6

mass % mass % mass % mass % mass % 15.0 1.4 41.0 74.3 55.0 100.0 71.0 1.1 26.0 2.2 42.0 19.3 56.0 90.4 81.0 1.2 27.0 26.3 43.0 20.5 57.0 9.9 83.0 4.2 28.0 3.7 50.0 1.8 65.0 1.3 98.0 43.4 C H 29.0 22.0 51.0 3.1 67.0 5.0 99.0 3.6 7 14 68.0 3.6 M+ = 98 38.0 2.1 52.0 1.4 39.0 27.6 53.0 9.9 69.0 48.1 trans-2-heptene 40.0 4.8 54.0 11.6 70.0 16.9

mass % mass % mass % mass % mass % 27.0 13.5 43.0 18.0 57.0 14.2 79.0 1.3 28.0 3.1 50.0 1.2 65.0 1.8 81.0 1.7 29.0 12.8 51.0 2.4 67.0 8.5 83.0 8.3 38.0 1.1 52.0 1.0 68.0 5.2 97.0 2.0 39.0 18.4 69.0 100.0 98.0 80.2 C7H14 53.0 7.7 M+ = 98 40.0 3.7 54.0 8.3 70.0 28.3 99.0 6.1 41.0 95.3 55.0 82.5 71.0 1.6 trans-3-heptene 42.0 23.7 56.0 98.8 77.0 1.0

mass % mass % mass % mass % mass % 15.0 1.4 41.0 87.8 53.0 7.6 69.0 49.4 26.0 1.7 42.0 22.8 54.0 9.7 70.0 17.6 27.0 24.8 43.0 27.5 55.0 79.3 71.0 2.6 28.0 4.9 44.0 1.0 56.0 100.0 81.0 1.2 C H 29.0 23.4 45.0 1.1 57.0 18.4 83.0 4.5 7 14 65.0 1.0 98.0 43.3 M+ = 98 38.0 1.6 50.0 1.5 39.0 23.0 51.0 2.4 67.0 4.0 99.0 3.9 cis-2-heptene 40.0 4.3 52.0 1.0 68.0 3.6

mass % mass % mass % mass % mass % 27.0 11.7 53.0 3.2 83.0 1.1 28.0 3.1 54.0 1.6 98.0 3.1 29.0 8.9 55.0 17.7 39.0 10.5 56.0 100.0 C7H14 40.0 2.9 57.0 10.5 M+ = 98 41.0 46.6 67.0 1.5 42.0 5.6 69.0 9.9 2-methy l-1-hexene 43.0 11.5 70.0 12.4

mass % mass % mass % mass % mass % 15.0 1.4 41.0 82.1 55.0 69 72.0 1.2 98.0 35.9 26.0 1.1 42.0 6.1 56.0 19 73.0 1.0 99.0 3.2 27.0 15.5 43.0 8.2 57.0 2 77.0 1.0 28.0 3.3 50.0 1.7 65.0 2 79.0 1.4 C H 29.0 12.2 51.0 3.2 67.0 7 81.0 2.5 7 14 38.0 1.5 M+ = 98 52.0 1.4 68.0 3 83.0 14.9 39.0 18.9 53.0 8.2 69.0 100 84.0 1.1 3-methy l-3-hexene 40.0 3.4 54.0 2.2 70.0 13 85.0 1.5

mass % mass % mass % mass % mass % 15.0 2.2 40.0 3.4 54.0 2.3 68.0 1.6 83.0 82.9 18.0 1.0 41.0 65.3 55.0 100.0 69.0 21.1 84.0 5.7 27.0 14.1 42.0 5.1 56.0 13.7 70.0 4.5 85.0 4.8 28.0 2.3 43.0 18.9 57.0 4.6 71.0 1.0 98.0 37.8 C H 29.0 12.8 50.0 1.3 58.0 1.8 72.0 5.2 99.0 4.1 7 14 31.0 1.3 M+ = 98 51.0 2.5 59.0 8.9 73.0 3.5 38.0 1.1 52.0 1.2 65.0 1.7 79.0 1.5 2,3-dimethy l-2-pentene 39.0 17.9 53.0 7.6 67.0 7.3 81.0 4.2 y:\files\classes\Spectroscopy Book home\1 Spectroscopy Workbook, latest MS full chapter.doc Spectroscopy Beauchamp 66

mass % mass % mass % mass % mass % 15.0 1.7 41.0 77.6 55.0 96.8 69.0 61.7 84.0 3.7 26.0 2.4 42.0 75.4 56.0 100.0 70.0 85.7 91.0 2.0 27.0 23.2 43.0 14.1 57.0 17.9 71.0 5.1 92.0 1.4 28.0 4.8 50.0 1.6 63.0 1.0 77.0 1.1 95.0 1.1 29.0 23.9 51.0 2.9 65.0 2.0 79.0 1.5 96.0 3.4 C7H14 38.0 2.2 52.0 1.3 66.0 1.7 81.0 7.5 97.0 1.7 M+ = 98 39.0 30.9 53.0 8.5 67.0 13.2 82.0 4.6 98.0 62.9 cycloheptane 40.0 6.2 54.0 18.4 68.0 27.2 83.0 48.6 99.0 5.0

mass % mass % mass % mass % mass % 26.0 1.0 42.0 28.6 67.0 4.5 84.0 7.0 27.0 12.9 43.0 6.9 68.0 9.3 97.0 2.8 28.0 3.2 51.0 1.9 69.0 22.5 98.0 36.9 29.0 11.1 53.0 4.6 70.0 21.8 99.0 3.1 38.0 1.0 54.0 4.5 71.0 1.4 C7H14 39.0 15.6 55.0 76.3 81.0 1.4 M+ = 98 40.0 2.9 56.0 28.5 82.0 14.5 methylcyclohexane 41.0 41.1 57.0 5.0 83.0 100.0

mass % mass % mass % mass % mass % 15.0 1.0 41.0 63.7 56.0 44.7 83.0 8.2 26.0 1.4 42.0 41.3 57.0 7.4 98.0 12.3 27.0 13.7 43.0 7.0 65.0 1.2 99.0 1.0 28.0 2.6 50.0 1.0 67.0 10.0 29.0 12.5 51.0 1.7 68.0 66.4 C7H14 38.0 1.2 53.0 5.1 69.0 100.0 M+ = 98 39.0 18.6 54.0 5.3 70.0 56.1 ethylcyclopentane 40.0 3.5 55.0 47.9 71.0 3.2

mass % mass % mass % mass % mass % 27.0 9.6 43.0 17.4 69.0 2.4 28.0 2.3 51.0 1.6 81.0 1.4 29.0 8.3 53.0 3.9 83.0 88.4 38.0 1.1 55.0 100.0 84.0 6.0 39.0 18.0 56.0 11.2 98.0 18.4 C7H14 40.0 3.0 57.0 2.0 99.0 1.4 M+ = 98 41.0 48.6 65.0 1.1 1,1,2,2-tet ramethylcyclopropane 42.0 2.7 67.0 3.7

Alcohols and ethers mass % mass % mass % mass % mass % 15.0 1.3 40.0 2.4 55.0 65.7 73.0 2.0 18.0 3.2 41.0 62.6 56.0 95.5 83.0 7.4 26.0 1.2 42.0 48.5 57.0 23.4 98.0 5.6 27.0 20.2 43.0 66.7 67.0 1.8 116.0 0.0 OH 28.0 4.6 44.0 2.7 68.0 13.3 C7H16O 29.0 27.2 45.0 3.6 69.0 51.6 M+ = 116 31.0 25.6 53.0 2.5 70.0 100.0 1-heptanol 39.0 11.3 54.0 5.6 71.0 6.3

OH mass % mass % mass % mass % mass % 27.0 5.1 45.0 100.0 98.0 4.0 29.0 5.4 46.0 2.3 101.0 3.7 31.0 1.5 55.0 14.9 116.0 0.0 39.0 3.2 56.0 6.8 41.0 10.0 57.0 3.5 C7H16O 42.0 3.6 69.0 2.7 M+ = 116 43.0 8.1 70.0 4.8 2-heptanol 44.0 6.9 83.0 8.9 mass % mass % mass % mass % mass % 27.0 9.8 43.0 11.4 59.0 100.0 98.0 2.9 28.0 2.1 44.0 2.9 60.0 3.3 116.0 0.0 29.0 11.1 45.0 8.1 69.0 70.2 OH 30.0 1.1 53.0 1.1 70.0 5.4 31.0 22.1 55.0 8.0 73.0 1.0 C7H16O 39.0 5.3 56.0 5.8 86.0 2.7 M+ = 116 41.0 34.9 57.0 8.1 87.0 31.3 3-heptanol 42.0 2.9 58.0 8.0 88.0 1.8

Spectroscopy Beauchamp 67

OH mass % mass % mass % mass % mass % 18.0 1.1 42.0 2.5 69.0 4.0 19.0 1.1 43.0 33.4 70.0 1.3 27.0 9.8 44.0 5.4 71.0 3.2 28.0 1.1 45.0 4.6 72.0 6.3 29.0 6.9 53.0 1.2 73.0 71.4 C7H16O 31.0 11.1 55.0 100.0 74.0 3.4 M+ = 116 39.0 5.4 56.0 9.2 98.0 2.0 4-heptanol 41.0 13.1 116.0 0.0 57.0 4.4 OH mass % mass % mass % mass % mass % 18.0 1.7 43.0 12.5 67.0 1.2 27.0 8.5 45.0 73.7 69.0 28.1 28.0 1.5 46.0 1.7 70.0 2.7 C H O 29.0 13.9 53.0 1.9 83.0 1.6 7 16 31.0 6.1 87.0 100.0 M+ = 116 55.0 8.2 39.0 4.2 56.0 2.3 88.0 5.4 41.0 24.9 57.0 11.2 98.0 2.8 3-ethy l-3-pentanol 42.0 1.5 59.0 2.5 116.0 0.0

mass % mass % mass % mass % mass % 15.0 2.0 42.0 13.1 57.0 3.4 27.0 5.9 43.0 13.3 69.0 13.2 28.0 1.9 45.0 100.0 70.0 2.4 O 29.0 8.2 46.0 2.4 83.0 1.3 31.0 1.8 C H O 47.0 1.3 84.0 19.4 7 16 33.0 5.2 54.0 1.3 85.0 1.8 M+ = 116 39.0 4.5 55.0 16.4 116.0 0.0 1-methoxyhexane 41.0 14.1 56.0 53.7

OH mass % mass % mass % mass % mass % 15.0 1.3 39.0 12.7 53.0 4.8 68.0 38.6 85.0 5.6 18.0 1.4 40.0 2.8 54.0 15.9 69.0 4.0 86.0 4.1 26.0 1.0 41.0 25.0 55.0 23.1 70.0 13.0 95.0 2.9 27.0 11.9 42.0 14.8 56.0 4.4 71.0 14.9 96.0 22.6 C H O 28.0 2.8 43.0 10.3 57.0 100.0 72.0 6.3 97.0 2.0 7 14 29.0 12.0 M+ = 114 44.0 22.5 58.0 9.1 81.0 34.2 113.0 1.1 30.0 1.1 45.0 5.3 66.0 2.0 82.0 2.5 114.0 2.1 cycloheptanol 31.0 5.4 51.0 1.1 67.0 19.8 83.0 1.4

OH mass % mass % mass % mass % mass % mass % 15.0 1.5 39.0 12.7 53.0 5.5 67.0 10.7 81.0 47.2 113.0 1.4 18.0 2.4 40.0 2.6 54.0 7.7 68.0 11.8 82.0 3.7 114.0 2.8 26.0 1.1 41.0 34.8 55.0 31.1 69.0 3.1 83.0 2.2 27.0 13.5 42.0 9.9 56.0 12.0 70.0 34.1 85.0 3.8 C7H14O 28.0 3.7 43.0 7.8 57.0 100.0 71.0 12.6 86.0 3.1 M+ = 114 29.0 19.8 44.0 17.0 58.0 52.8 73.0 1.7 95.0 6.0 30.0 1.7 45.0 3.3 59.0 2.7 77.0 1.0 96.0 35.0 4-methylcyclohexanol 31.0 5.7 51.0 1.5 65.0 1.0 79.0 2.0 97.0 3.1

OH mass % mass % mass % mass % mass % 18.0 1.3 42.0 9.6 56.0 7.0 71.0 1.9 27.0 10.6 43.0 4.8 57.0 7.3 79.0 1.5 28.0 2.5 44.0 5.8 58.0 1.0 81.0 23.9 29.0 8.4 45.0 2.4 65.0 1.2 82.0 2.2 31.0 11.0 C H O 51.0 1.2 66.0 7.6 83.0 7.5 7 14 39.0 13.4 53.0 7.5 95.0 3.0 M+ = 114 67.0 99.6 40.0 3.8 54.0 12.3 68.0 100.0 96.0 4.0 2-cyclopentylethanol 41.0 40.7 55.0 36.9 69.0 15.4 114.0 0.0

mass % mass % mass % mass % mass % O 15.0 1.4 38.0 1.1 56.0 13.3 114.0 0.0 18.0 1.3 39.0 13.4 57.0 42.9 26.0 1.8 40.0 3.0 58.0 72.2 27.0 9.9 41.0 100.0 59.0 3.8 C7H14O 28.0 4.0 42.0 7.6 71.0 10.7 M+ = 114 29.0 24.7 43.0 16.0 72.0 1.8 30.0 3.2 44.0 1.9 73.0 2.8 3-butoxypropene 31.0 3.2 55.0 10.4 85.0 1.9

y:\files\classes\Spectroscopy Book home\1 Spectroscopy Workbook, latest MS full chapter.doc Spectroscopy Beauchamp 68

mass % mass % mass % mass % mass % O 15.0 1.2 43.0 4.7 58.0 3.8 112.0 1.0 27.0 8.0 44.0 1.3 59.0 29.5 115.0 1.0 28.0 2.0 45.0 100.0 60.0 1.0 130.0 0.2 29.0 23.8 46.0 2.2 73.0 5.4 C H O 31.0 2.9 53.0 1.0 83.0 9.7 8 18 39.0 5.2 55.0 8.3 97.0 1.1 M+ = 130 41.0 28.8 56.0 6.8 101.0 39.1 di-sec-butyl ether 42.0 1.7 57.0 84.5 102.0 2.6

mass % mass % mass % mass % mass % 27.0 4.0 55.0 2.0 29.0 12.4 56.0 4.7 O 31.0 1.0 57.0 100.0 39.0 4.2 58.0 4.6 C H O 41.0 19.3 59.0 1.7 8 18 42.0 2.2 M+ = 130 73.0 1.0 43.0 3.6 87.0 8.2 di-isobutyl ether 45.0 2.0 130.0 2.6

Amines

Spectroscopy Beauchamp 69

Haloalkanes

mass % mass % mass % mass % mass % 15.0 1.3 38.0 3.1 63.0 4.7 18.0 1.3 39.0 11.4 65.0 1.4 26.0 3.9 40.0 3.1 78.0 2.7 Cl 27.0 31.9 41.0 23.2 80.0 0.8 C3H7Cl 28.0 12.9 42.0 100.0 M+ = 78.5 29.0 40.6 43.0 13.7 36.0 1.2 (78 & 80) 49.0 4.2 37.0 2.3 51.0 1.3 1-chloropropane

mass % mass % mass % mass % mass % 15.0 1.7 41.0 21.8 78.0 9.0 26.0 2.4 42.0 6.6 80.0 3.1 27.0 29.3 43.0 100.0 Cl 36.0 1.2 44.0 3.6 C3H7Cl 37.0 1.5 62.0 1.8 M+ = 78.5 38.0 2.4 63.0 17.0 (78 & 80) 39.0 8.5 65.0 5.7 40.0 2.1 2-chloropropane

mass % mass % mass % mass % mass % 18.0 1.4 41.0 57.5 55.0 7.5 26.0 3.7 42.0 5.0 56.0 100.0 27.0 26.3 43.0 36.6 57.0 5.8 Cl 28.0 15.0 44.0 1.1 62.0 1.3 63.0 4.8 C3H7Cl 29.0 16.7 49.0 2.8 M+ = 92.6 38.0 1.4 51.0 1.1 65.0 1.4 (78 & 80) 39.0 10.0 53.0 1.2 40.0 2.2 1-chlorobutane

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mass % mass % mass % mass % mass % 15.0 1.9 39.0 17.9 55.0 3.9 26.0 1.9 40.0 2.6 56.0 8.1 41.0 66.8 57.0 100.0 Cl 27.0 10.4 28.0 1.4 42.0 3.2 58.0 4.3 76.0 3.1 C3H7Cl 29.0 22.3 49.0 2.2 M+ = 92.6 36.0 3.1 51.0 1.3 77.0 38.3 79.0 12.2 (90 & 92) 37.0 1.4 53.0 1.3 38.0 2.6 2-chloro-2-methylpropane

mass % mass % mass % mass % mass % 15.0 1.3 39.0 16.7 53.0 3.7 67.0 2.7 91.0 100.0 18.0 3.2 40.0 2.9 69.0 22.1 93.0 32.0 Cl 54.0 3.9 26.0 2.2 41.0 59.0 55.0 81.1 70.0 2.1 27.0 27.0 42.0 44.7 56.0 56.5 71.0 2.8 C6H13Cl 28.0 5.0 43.0 72.0 57.0 14.7 82.0 1.2 M+ = 120.6 29.0 32.0 44.0 2.5 62.0 1.2 83.0 1.3 (120 & 122) 31.0 1.4 49.0 3.0 63.0 4.7 84.0 4.2 38.0 1.2 51.0 1.4 65.0 1.5 1-chlorohexane

mass % mass % mass % mass % mass % 15.0 1.6 40.0 2.1 107.0 1.5 26.0 2.4 41.0 31.0 109.0 1.2 Br 27.0 25.6 42.0 7.7 122.0 8.6 28.0 1.6 43.0 100.0 124.0 8.3 44.0 3.5 C3H7Br 29.0 4.0 M+ = 123 37.0 1.2 93.0 1.1 95.0 1.0 (122 & 124) 38.0 2.2 39.0 9.0 1-bromohexane

mass % mass % mass % mass % mass % 15.0 1.4 41.0 31.9 26.0 2.2 42.0 4.0 27.0 27.4 43.0 100.0 Br 28.0 1.1 44.0 3.6 C H Br 37.0 1.2 107.0 1.1 3 7 38.0 2.1 M+ = 123 109.0 1.0 39.0 9.9 122.0 5.9 (122 & 124) 40.0 1.9 124.0 5.7 2-bromohexane

mass % mass % mass % mass % mass % 15.0 1.5 41.0 64.5 57.0 100.0 136.0 7.9 26.0 5.7 42.0 3.2 58.0 4.6 138.0 7.8 Br 27.0 29.4 43.0 3.9 79.0 1.0 28.0 13.3 50.0 1.6 81.0 1.0 C4H9Br 29.0 40.9 51.0 1.4 93.0 1.4 M+ = 137 38.0 2.0 53.0 1.5 95.0 1.3 (136 & 138) 39.0 14.8 55.0 7.2 107.0 3.7 40.0 2.2 56.0 16.4 109.0 3.6 1-bromobutane

mass % mass % mass % mass % mass % 15.0 1.4 41.0 53.2 58.0 4.4 26.0 3.9 42.0 2.9 107.0 1.2 50.0 1.6 Br 27.0 18.6 109.0 1.0 28.0 5.3 51.0 1.5 136.0 0.6 C4H9Br 29.0 40.9 53.0 1.6 138.0 0.6 M+ = 137 38.0 1.8 55.0 4.9 (136 & 138) 39.0 14.3 56.0 8.0 40.0 1.7 57.0 100.0 2-bromobutane

Spectroscopy Beauchamp 71

mass % mass % mass % mass % mass % 26.0 1.2 43.0 66.4 69.0 7.5 99.0 14.5 164.0 0.4 27.0 16.5 44.0 2.2 70.0 3.2 100.0 1.2 166.0 0.4 107.0 1.2 Br 28.0 2.7 53.0 2.4 71.0 2.8 29.0 20.7 54.0 1.3 81.0 1.0 109.0 1.0 39.0 10.8 55.0 25.7 83.0 1.5 135.0 8.3 C6H13Br 137.0 8.0 M+ = 165.1 40.0 1.9 56.0 14.6 84.0 1.2 41.0 41.8 57.0 100.0 85.0 18.2 (164 & 166) 42.0 10.3 58.0 4.9 86.0 1.3 1-bromohexane

mass % mass % mass % mass % mass % 15.0 1.7 42.0 3.3 26.0 1.7 43.0 100.0 I+ = 127 44.0 3.3 I 27.0 31.7 28.0 1.7 127.0 4.9 + 38.0 1.5 128.0 1.2 HI = 128 C3H7I 39.0 10.7 170.0 23.3 M+ = 170.0 40.0 2.0 41.0 36.8 1-iodopropane

mass % mass % mass % mass % mass % 15.0 1.1 42.0 3.6 43.0 100.0 26.0 1.4 I+ = 127 27.0 27.7 44.0 3.4 28.0 1.6 127.0 5.8 I 38.0 1.6 128.0 1.7 HI+ = 128 170.0 24.3 C3H7I 39.0 11.5 M+ = 170.0 40.0 2.0 41.0 35.8 2-iodopropane

mass % mass % mass % mass % mass % 26.0 1.2 43.0 100.0 141.0 1.2 27.0 18.8 44.0 3.4 155.0 2.3 28.0 2.5 53.0 1.3 198.0 9.5 I+ = 127 I 29.0 23.1 55.0 9.9 39.0 10.6 71.0 73.2 + C5H11I 40.0 2.0 72.0 4.3 HI = 128 M+ = 198.0 41.0 30.1 127.0 2.1 42.0 8.3 128.0 0.6 1-iodopentane

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Aldehydes and ketones O mass % mass % mass % mass % mass % 14.0 2.0 30.0 7.8 58.0 85.0 15.0 4.7 31.0 5.6 59.0 12.1 18.0 5.2 37.0 2.4 H 25.0 2.4 38.0 2.3 26.0 16.4 39.0 4.0 C3H6O M+ = 58 27.0 59.0 40.0 1.7 28.0 90.8 56.0 1.7 propanal 29.0 100.0 57.0 7.3

mass % mass % mass % mass % mass % O 14.0 2.9 39.0 4.2 59.0 3.1 15.0 23.1 40.0 1.0 26.0 3.5 41.0 2.0 27.0 5.7 42.0 9.1 C3H6O 28.0 1.2 43.0 100.0 M+ = 58 29.0 3.1 44.0 3.4 propanone 37.0 1.8 57.0 1.7 38.0 2.2 58.0 63.8

mass % mass % mass % mass % mass % O 14.0 1.7 31.0 2.6 43.0 75.3 60.0 2.7 15.0 5.9 32.0 1.3 44.0 100.0 71.0 5.4 18.0 1.2 37.0 3.1 45.0 3.2 72.0 53.6 H 26.0 8.2 38.0 5.3 50.0 1.1 73.0 2.7 C4H8O 27.0 73.5 39.0 27.3 53.0 1.1 M+ = 72 28.0 19.6 40.0 3.5 54.0 2.3 29.0 54.8 41.0 69.1 55.0 1.5 butanal 30.0 1.2 42.0 9.4 57.0 23.3

O mass % mass % mass % mass % mass % 15.0 2.4 38.0 5.7 50.0 1.0 26.0 5.6 39.0 28.7 53.0 1.5 H 27.0 54.9 40.0 3.9 55.0 3.3 28.0 13.1 41.0 86.7 56.0 1.8 C4H8O 29.0 31.5 42.0 14.0 57.0 6.9 M+ = 72 31.0 1.5 43.0 100.0 71.0 4.4 37.0 3.4 44.0 7.4 72.0 92.3 pentanal 45.0 1.1 73.0 5.9

mass % mass % mass % mass % mass % O 14.0 1.2 41.0 1.1 15.0 6.6 42.0 4.1 18.0 1.3 43.0 100.0 26.0 2.6 44.0 2.6 C H O 27.0 8.9 57.0 8.0 4 8 28.0 1.3 M+ = 72 72.0 22.1 29.0 18.8 73.0 1.0 butanone 39.0 1.6

O mass % mass % mass % mass % mass % 15.0 3.9 39.0 12.3 55.0 4.4 71.0 1.8 26.0 3.4 40.0 2.2 56.0 2.2 73.0 1.1 27.0 28.2 41.0 41.0 57.0 19.8 85.0 1.2 H 28.0 10.5 42.0 11.1 58.0 31.4 86.0 1.1 43.0 18.7 59.0 1.3 C5H10O 29.0 52.3 M+ = 86 30.0 2.2 44.0 100.0 60.0 2.9 31.0 1.9 45.0 12.2 67.0 1.1 pentanal 38.0 1.3 53.0 1.6 68.0 1.0

O mass % mass % mass % mass % mass % 15.0 4.2 38.0 5.0 50.0 2.5 60.0 2.7 87.0 1.2 26.0 2.8 39.0 38.7 51.0 2.4 67.0 1.9 27.0 41.9 40.0 5.7 53.0 5.7 68.0 2.3 H 28.0 4.0 41.0 89.8 55.0 6.2 69.0 2.6 42.0 24.6 71.0 36.0 C5H10O 29.0 46.3 56.0 3.6 M+ = 86 30.0 1.0 43.0 93.4 57.0 37.0 72.0 1.7 31.0 1.3 44.0 100.0 58.0 81.4 85.0 2.8 3-methylbutanal 37.0 2.3 45.0 19.6 59.0 3.1 86.0 11.7

Spectroscopy Beauchamp 73

O mass % mass % mass % mass % mass % 15.0 2.3 37.0 1.1 45.0 3.0 59.0 2.7 86.0 6.3 18.0 2.3 38.0 1.9 50.0 1.4 67.0 1.1 87.0 3.2 H 26.0 4.5 39.0 18.4 51.0 1.5 69.0 1.3 27.0 31.1 40.0 2.7 53.0 3.6 70.0 2.3 C5H10O 28.0 9.4 41.0 92.4 55.0 9.4 71.0 4.9 M+ = 86 29.0 100.0 42.0 5.8 56.0 7.8 73.0 1.8 30.0 4.0 43.0 11.9 57.0 95.8 74.0 11.1 3-methylbutanal 31.0 1.7 44.0 3.8 58.0 60.0 85.0 1.8

O mass % mass % mass % mass % mass % 15.0 2.3 37.0 1.1 51.0 1.3 86.0 18.1 18.0 3.0 38.0 2.5 53.0 2.1 87.0 3.1 26.0 1.7 39.0 19.4 55.0 5.5 H 27.0 16.4 40.0 2.6 56.0 2.8 C5H10O 28.0 3.2 41.0 83.5 57.0 100.0 M+ = 86 29.0 51.5 42.0 8.8 58.0 5.2 30.0 1.1 43.0 26.6 59.0 1.5 2,2-dimethylpropanal 32.0 1.0 50.0 1.2 71.0 1.6

O mass % mass % mass % mass % mass % 15.0 4.8 42.0 4.0 26.0 1.3 43.0 100.0 27.0 10.5 44.0 2.3 28.0 1.3 58.0 10.3 C5H10O 29.0 1.9 71.0 11.0 M+ = 86 38.0 1.2 86.0 20.2 87.0 1.2 2-pentanone 39.0 6.3 41.0 11.9

mass % mass % O mass % mass % mass % 26.0 2.5 43.0 1.6 27.0 12.4 55.0 1.3 28.0 4.3 56.0 3.7 29.0 59.4 57.0 100.0 C5H10O 30.0 1.4 58.0 3.4 M+ = 86 39.0 1.8 86.0 21.2 87.0 1.2 3-pentanone 41.0 2.0 42.0 1.8

O mass % mass % mass % mass % mass % 14.0 1.6 39.0 16.3 51.0 1.1 15.0 9.8 40.0 2.1 57.0 3.7 26.0 3.1 41.0 26.2 71.0 6.9 27.0 19.3 42.0 4.9 86.0 22.6 C5H10O 28.0 3.1 43.0 100.0 87.0 1.0 M+ = 86 29.0 3.5 44.0 2.4 37.0 1.4 45.0 1.3 3-methyl-2-butanone 38.0 2.9 50.0 1.3

O mass % mass % mass % mass % mass % 15.0 2.2 38.0 1.9 50.0 1.0 60.0 3.6 83.0 1.0 18.0 1.0 39.0 20.1 51.0 1.3 67.0 8.1 100.0 0.4 H 26.0 2.7 40.0 3.8 53.0 2.9 69.0 1.4 27.0 33.9 41.0 69.1 54.0 2.3 71.0 6.7 C H O 28.0 8.1 42.0 10.8 55.0 15.3 72.0 16.7 6 12 73.0 1.8 M+ = 100 29.0 33.0 43.0 55.1 56.0 82.0 30.0 1.6 44.0 100.0 57.0 38.1 81.0 1.2 hexanal 31.0 1.8 45.0 19.5 58.0 9.0 82.0 12.8

O mass % mass % mass % mass % mass % 15.0 1.0 39.0 11.4 56.0 1.7 72.0 1.0 18.0 1.0 40.0 1.9 57.0 12.1 74.0 1.7 H 26.0 1.5 41.0 27.2 58.0 90.1 100.0 2.0 27.0 17.6 42.0 5.2 59.0 3.4 C6H12O 28.0 2.1 43.0 100.0 67.0 1.3 M+ = 100 29.0 21.4 44.0 3.4 69.0 1.3 30.0 2.5 53.0 1.9 70.0 1.2 2-methylpentanal 38.0 1.0 55.0 10.3 71.0 15.3

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O mass % mass % mass % mass % mass % 26.0 1.2 43.0 100.0 59.0 1.2 88.0 1.5 27.0 14.9 44.0 5.5 67.0 2.6 100.0 3.1 H 28.0 2.0 53.0 2.7 69.0 1.7 29.0 22.2 54.0 1.6 70.0 2.9 39.0 10.9 C6H12O 55.0 12.6 71.0 34.2 M+ = 100 40.0 1.3 56.0 2.9 72.0 48.1 41.0 27.5 57.0 15.3 73.0 3.1 2-ethylbutanal 42.0 4.9 58.0 3.8 82.0 4.9 O mass % mass % mass % mass % mass % 15.0 3.6 42.0 3.1 85.0 6.4 18.0 1.9 43.0 100.0 100.0 8.0 26.0 1.1 44.0 2.4 27.0 8.2 55.0 1.4 C6H12O 28.0 2.0 57.0 15.8 M+ = 100 29.0 14.8 58.0 49.8 2-hexanone 39.0 5.6 59.0 3.1 71.0 5.4 41.0 14.1 O mass % mass % mass % mass % mass % 15.0 2.4 38.0 1.0 55.0 2.4 101.0 2.0 18.0 1.8 39.0 7.9 56.0 1.8 26.0 2.9 40.0 1.2 57.0 84.9 27.0 27.6 41.0 20.3 58.0 3.1 C6H12O 28.0 7.5 42.0 3.6 71.0 54.0 M+ = 100 29.0 53.0 43.0 100.0 72.0 6.1 3-hexanone 30.0 1.1 44.0 3.4 85.0 2.9 32.0 1.6 53.0 1.0 100.0 28.6

O mass % mass % mass % mass % mass % 15.0 5.1 42.0 3.1 67.0 1.9 27.0 7.2 43.0 100.0 72.0 1.3 28.0 1.7 44.0 2.6 85.0 17.7 29.0 11.0 55.0 1.4 86.0 1.0 31.0 1.1 100.0 19.0 C6H12O 56.0 1.4 M+ = 100 39.0 8.3 57.0 24.9 101.0 1.4 40.0 1.3 58.0 42.6 4-methyl-2-pentanone 41.0 19.2 59.0 3.5

O mass % mass % mass % mass % mass % 15.0 2.9 43.0 100.0 67.0 1.6 26.0 1.0 44.0 4.4 71.0 2.4 27.0 8.0 45.0 2.5 72.0 50.7 28.0 2.2 53.0 1.6 73.0 2.2 C6H12O 29.0 33.6 55.0 5.1 85.0 8.3 M+ = 100 39.0 7.1 56.0 23.5 100.0 17.6 41.0 41.8 57.0 67.9 101.0 2.4 3-methyl-2-pentanone 42.0 4.0 58.0 3.3

O mass % mass % mass % mass % mass % mass % 15.0 2.0 39.0 19.2 53.0 4.0 67.0 8.8 82.0 2.2 97.0 2.1 26.0 2.1 40.0 3.3 54.0 7.6 68.0 17.5 83.0 3.2 114.0 1.5 27.0 30.7 41.0 66.7 55.0 58.6 69.0 7.1 84.0 1.2 H 28.0 7.4 42.0 53.0 56.0 9.7 70.0 93.7 85.0 4.1 57.0 46.5 71.0 23.7 C7H14O 29.0 40.2 43.0 84.0 86.0 15.4 M+ = 114 30.0 1.5 44.0 100.0 58.0 6.4 72.0 8.5 87.0 1.3 31.0 1.9 45.0 21.9 59.0 1.0 74.0 2.0 95.0 2.2 heptanal 38.0 1.2 51.0 1.5 60.0 1.1 81.0 19.2 96.0 14.4

O mass % mass % mass % mass % mass % mass % 27.0 9.8 43.0 70.9 59.0 4.3 28.0 3.4 44.0 2.4 69.0 1.5 H 29.0 25.0 45.0 1.2 70.0 1.5 30.0 2.7 53.0 1.9 74.0 2.5 C7H14O 39.0 6.9 55.0 7.2 85.0 9.9 M+ = 114 40.0 1.2 56.0 7.9 91.0 1.3 41.0 31.1 57.0 31.8 97.0 1.5 2,3-dimethylpentanal 42.0 1.9 58.0 100.0

Spectroscopy Beauchamp 75

O mass % mass % mass % mass % mass % 15.0 4.2 42.0 3.0 58.0 90.6 115.0 1.0 18.0 1.5 43.0 100.0 59.0 14.8 27.0 8.9 44.0 2.4 71.0 14.0 28.0 2.0 45.0 1.4 72.0 3.9 C7H14O 29.0 8.7 53.0 1.0 85.0 3.3 M+ = 114 39.0 6.7 55.0 5.1 99.0 4.1 40.0 1.0 56.0 1.5 113.0 1.7 2-heptanone 41.0 11.6 57.0 1.6 114.0 9.5

O mass % mass % mass % mass % mass % 15.0 1.2 41.0 33.7 59.0 1.2 26.0 2.5 42.0 2.8 71.0 5.6 27.0 22.8 43.0 15.2 72.0 32.9 28.0 8.2 53.0 1.5 73.0 2.0 C7H14O 29.0 79.1 55.0 3.6 85.0 43.3 M+ = 114 30.0 1.8 56.0 2.8 86.0 2.6 39.0 8.8 57.0 100.0 114.0 14.0 3-heptanone 40.0 1.0 58.0 4.4 115.0 1.1

mass % O mass % mass % mass % mass % 15.0 1.5 42.0 2.6 72.0 3.8 26.0 1.0 43.0 100.0 86.0 1.4 27.0 15.9 44.0 3.5 99.0 2.0 28.0 1.1 55.0 2.2 114.0 14.4 57.0 1.4 115.0 1.2 C7H14O 29.0 2.9 M+ = 114 39.0 6.3 58.0 6.7 40.0 1.0 70.0 1.2 4-heptanone 41.0 17.5 71.0 84.7

O mass % mass % mass % mass % mass % 15.0 1.4 41.0 25.7 69.0 1.2 115.0 1.5 26.0 1.3 42.0 3.0 71.0 1.5 27.0 13.3 43.0 15.1 72.0 14.0 28.0 2.6 53.0 1.0 73.0 1.0 C H O 29.0 44.8 55.0 1.6 85.0 41.3 7 14 86.0 2.8 M+ = 114 30.0 1.0 56.0 1.7 39.0 8.0 57.0 100.0 99.0 4.3 5-methyl-3-hexanone 40.0 1.2 58.0 5.0 114.0 20.4

O mass % mass % mass % mass % mass % 15.0 4.6 42.0 2.1 59.0 12.4 18.0 1.0 43.0 100.0 71.0 9.6 27.0 9.3 44.0 2.4 72.0 1.2 28.0 1.6 53.0 1.3 81.0 4.8 55.0 4.1 85.0 1.4 C7H14O 29.0 7.1 M+ = 114 39.0 7.0 56.0 3.8 86.0 1.2 40.0 1.0 57.0 14.8 99.0 2.3 5-methyl-2-hexanone 41.0 13.3 58.0 50.2 114.0 4.3

O mass % mass % mass % mass % mass % 15.0 1.1 43.0 100.0 71.0 59.5 27.0 16.0 44.0 3.8 72.0 3.4 28.0 1.7 53.0 1.2 86.0 15.3 29.0 11.5 55.0 5.5 87.0 2.5 39.0 7.0 57.0 2.5 99.0 34.3 C9H18O 40.0 1.4 58.0 34.4 100.0 3.4 M+ = 142 41.0 18.7 59.0 1.5 142.0 5.2 4-nonanone 42.0 4.2 70.0 1.5

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Esters

mass % mass % mass % mass % mass % O 15.0 1.9 40.0 1.7 56.0 2.6 72.0 1.5 98.0 1.3 26.0 1.8 41.0 22.3 57.0 2.5 73.0 23.3 99.0 51.9 27.0 22.3 42.0 10.1 59.0 1.0 74.0 4.1 100.0 3.5 O 28.0 4.0 43.0 61.0 60.0 38.9 83.0 1.3 101.0 25.8 C8H16O2 29.0 49.8 44.0 2.2 61.0 23.6 87.0 6.8 102.0 3.6 M+=144 30.0 1.4 45.0 17.4 69.0 5.5 88.0 100.0 115.0 8.0 31.0 1.5 53.0 1.3 70.0 22.9 89.0 5.8 ethyl hexanoate 116.0 1.0 39.0 8.7 55.0 12.4 71.0 26.1 97.0 2.0 117.0 5.0 144.0 1.6

Spectroscopy Beauchamp 77

mass % mass % mass % mass % mass % 15.0 1.0 40.0 2.7 56.0 12.4 86.0 3.7 144.0 0.6 O 26.0 1.1 41.0 43.4 57.0 92.6 87.0 11.0 27.0 13.0 42.0 9.6 58.0 4.1 102.0 10.5 28.0 5.7 43.0 100.0 59.0 10.0 103.0 32.0 44.0 3.3 69.0 1.4 104.0 1.8 C H O O 29.0 15.7 8 16 2 31.0 1.0 45.0 5.0 73.0 2.6 116.0 21.3 M+ = 144 38.0 1.3 53.0 1.0 74.0 19.5 117.0 1.4 isopropyl 2-methylbutanoate 55.0 4.2 85.0 66.8 129.0 5.0 39.0 12.0

Carboxylic acids

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mass % mass % mass % mass % mass % O 18.0 1.5 42.0 3.4 58.0 4.4 83.0 2.8 144.0 0.1 27.0 8.9 43.0 25.2 59.0 5.5 87.0 7.3 28.0 1.0 44.0 1.1 60.0 1.0 88.0 67.9 OH 29.0 11.9 45.0 2.5 69.0 3.3 89.0 3.1 C H O 31.0 1.1 53.0 2.2 70.0 3.8 99.0 28.5 8 16 2 55.0 11.5 100.0 2.2 M+ = 144 39.0 8.4 71.0 1.2 40.0 1.4 56.0 4.1 73.0 19.2 101.0 6.2 2,2-dimethylhexanoic acid 57.0 100.0 115.0 2.0 41.0 27.3 74.0 1.3

Alkynes

Acid chlorides

Nitriles

Anhydrides

Amides Spectroscopy Beauchamp 79

Amides

hexanamide N,N-diethylethanamide N-ethylpropanamide N-butylpropanamide 27.0 8.7 15.0 6.5 27.0 6.4 27.0 25.1 29.0 8.4 28.0 10.4 27.0 12.3 39.0 5.5 28.0 5.6 28.0 6.9 29.0 8.3 29.0 100.0 41.0 11.6 30.0 69.7 29.0 40.0 43.0 25.8 30.0 19.0 30.0 100.0 42.0 6.6 42.0 5.4 44.0 28.5 44.0 72.0 41.0 12.6 59.0 100.0 43.0 27.6 44.0 30.5 44.0 32.9 46.0 9.1 72.0 18.7 56.0 8.6 57.0 51.6 86.0 9.3 58.0 100.0 58.0 7.2 72.0 15.1 57.0 63.2 72.0 62.1 74.0 11.1 100.0 5.9 86.0 22.8 115.0 33.5 86.0 9.6 100.0 5.4 87.0 25.0 101.0 92.6 100.0 14.5 102.0 5.6 129.0 13.2

O O M+ = 115 M+ = 115 O O M+ = 101 M+ = 129 N NH 2 N N H H

heptanenitrile 1-heptyne 2-heptyne 3-heptyne 27.0 20.6 27.0 18.4 27.0 39.9 27.0 23.3 28.0 6.7 29.0 45.7 28.0 6.7 29.0 13.9 29.0 22.5 39.0 29.8 29.0 8.6 39.0 43.1 39.0 17.8 40.0 11.7 39.0 50.8 40.0 11.5 41.0 87.3 41.0 70.6 40.0 7.6 41.0 83.6 42.0 12.0 42.0 8.0 41.0 67.6 42.0 10.5 43.0 60.2 51.0 5.9 42.0 7.2 50.0 6.3 54.0 55.3 53.0 17.9 43.0 25.6 51.0 11.7 55.0 50.2 54.0 35.4 50.0 6.3 52.0 7.3 56.0 8.2 55.0 51.0 51.0 11.5 53.0 48.8 57.0 11.2 56.0 26.1 52.0 8.6 54.0 24.6 68.0 23.1 57.0 28.4 53.0 46.9 55.0 26.5 69.0 14.7 65.0 7.1 54.0 81.8 56.0 5.0 71.0 5.2 67.0 44.0 55.0 22.3 63.0 5.2 82.0 100.0 68.0 30.2 56.0 8.2 65.0 21.3 83.0 59.4 79.0 10.6 65.0 9.9 66.0 11.1 96.0 14.3 81.0 100.0 66.0 5.5 67.0 100.0 110.0 7.8 82.0 7.3 67.0 43.3 68.0 29.2 111.0 0.7 95.0 9.4 68.0 42.5 77.0 9.2 96.0 1.0 77.0 5.3 79.0 32.4 79.0 13.8 81.0 92.6 81.0 100.0 82.0 6.4 82.0 7.6 95.0 6.9 95.0 5.3 96.0 69.6 96.0 18.0

C N M+ = 111 M+ = 96 M+ = 96 M+ = 96

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Aromatics

hexylbenzene m-diisopropylbenzene p-diisopropylbenzene 27.0 6.0 27.0 5.2 39.0 5.4 41.0 9.3 29.0 5.6 41.0 13.1 39.0 5.5 43.0 19.2 43.0 33.4 77.0 5.5 41.0 7.6 65.0 5.2 43.0 16.6 91.0 19.2 66.0 5.2 105.0 21.8 65.0 8.8 77.0 7.2 78.0 6.4 117.0 7.5 79.0 5.6 119.0 30.8 91.0 100.0 91.0 25.7 92.0 95.1 131.0 5.0 105.0 30.2 147.0 100.0 93.0 7.7 119.0 41.8 105.0 11.2 148.0 12.4 133.0 6.5 162.0 33.1 133.0 5.4 147.0 100.0 162.0 33.2 148.0 14.4 162.0 36.4

M+ = 162 M+ = 162 M+ = 162