Figure 22.2: (a) Lewis stucture of ethane (C2H6). (b) molecular structure of ethane Name calling
H H C H H
HYBRIDIZATION? methane
Name calling Name calling
H H H H H H C C H H C C C H H H H H H
ethane propane
1 Name calling Name calling
H H H H H H H H H H C C C C H H C C C C C H H H H H H H H H H
butane pentane
Name calling Name calling
H H H H H H H H H H H H H H C C C C C C H H C C C C C C C H H H H H H H H H H H H H H
hexane heptane
Name calling Name calling
•CH4 methane •CH ethane H H H H H H H H 2 6 •C3H8 propane
H C C C C C C C C H •C4H10 butane •CH pentane H H H H H H H H 5 12 •C6H14 hexane
•C7H16 heptane octane •C8H18 octane
2 Figure 22.3: Structures of (a) propane Figure 22.3: Structures of (a) propane (b) butane (b) butane
H H H H H H H H C C C H H C C C C H H H H H H H H
H H H H H H H H C C C H H C C C C H HYBRIDIZATION? H H H H H H H
Figure 22.3: Structures of (a) propane Figure 22.3: Structures of (a) propane (b) butane (b) butane
C C C C C C C
C C
C C
3 H H H H CH H C C C C H CH3 H H CH3 CH
Reactions of Alkanes Learning Check Alk3
Combustion Complete and balance the reaction for the
complete combustion of C7H16
alkane + O2 CO2 + H2O + heat
Solution Alk3 Combustion In the Cell
Metabolic oxidation is combustion Step 1 C6H12 O6 + 6O2 6CO2 + 6H2O + heat C7H16 + O2 CO2 + H2O glucose Step 2 • How does this reaction occur in living
C7H16 + O2 7 CO2 + 8 H2O organisms? Step 3
C7H16 + 11 O2 7 CO2 + 8 H2O
4 Aerobic Oxidation Occurs in a Mitochondrion Located within a Cell
Alkyl Groups Branches on carbon chains Branched Alkanes H Structural Formulas H C H methane Structural Isomers H H H
H C C H ethane
H H
Alkyl Groups Branched Alkanes Branches on carbon chains H CH3
H C CH3 methyl CH3CHCH3 H methyl groups H H CH3 CH3
H C C CH3CH2 ethyl CH3CHCH2CHCH3 H H
5 Naming Branched Alkanes Naming Branched Alkanes
CH3 methyl branch
CH3 methyl branch CH3CH2CH2CHCH2CH3 6 5 4 3 2 1 Count CH3CH2CH2CHCH2CH3 3-Methylhexane 6 5 4 3 2 1 Count
on third C CH3 six carbon chain group
Naming Summary Learning Check Alk4
A. CH3 CH3
1. Count the C’s in the longest chain CHCH2CH 2. Name each attached group CH3 CH3 3 Count the longest carbon chain to B. CH3 CH3 give the first attached group the CH3CH2CHCH2CH smallest number CH3 CH2CH3 4. Name and locate each group
Solution Alk4 Learning Check Alk5
A. CH3 CH3 Write a condensed structure for A. 3,4-dimethylheptane CH3CHCH2CHCH3 2,4-dimethylpentane
B. CH3 CH3
B. 2,2-dimethyloctane CH3CH2CHCH2CHCH2CH3
CH3 3,3,5-trimethylheptane
6 Solution Alk5 Isomers
A. 3,4-dimethylheptane CH3 Same molecular formula Same number and types of atoms CH CH CHCHCH CH CH 3 2 2 2 3 Different arrangement of atoms
CH3
B. 2,2-dimethyloctane CH3
CH3CCH2CH2CH2CH2CH2CH3
CH3
Butane structures Learning Check Alk6
Write 3 isomers of C5H12 and name each.
n-butane
methylpropane
Cyclic Solution Alk6 Alkanes
CH3CH2CH2CH2CH3 pentane or n-pentane
CH3
CH CHCH CH 2-methylbutane 3 2 3 Cyclopropane structure CH3
CH3CCH3 2,2-dimethylpropane
CH3
7 Cyclohexane Figure 22.11: The structure of benzene structure
Cycloalkanes with Side Groups Naming Cycloalkanes with CH3 Side Groups methylcyclopentane Number of Naming side groups CH3
One Side group name goes in front CH3 1,2-dimethylcyclopentane of the cycloalkane name.
CH3 Two Number the ring in the CH3 direction that gives the lowest numbers 1,2,4-trimethylcyclohexane to the side groups.
CH3
Learning Check Alk8 Name the following cyclic alkanes Solution Alk8 CH 3 CH3
1,2-dimethylcyclobutane CH3 CH3
CH3 CH3
methylcyclopentane
CH CH3 3 1,3-dimethylcyclohexane
CH3 CH3
8 Saturated and Unsaturated Alkenes Compounds Carbon-carbon double bonds zSaturated compounds (alkanes) have Names end in -ene the maximum number of hydrogen atoms attached to each carbon atom H2C=CH2 ethene (ethylene) zUnsaturated compounds have fewer H C=CH-CH propene (propylene) hydrogen atoms attached to the carbon 2 3 chain than alkanes cyclohexene zUnsaturated compounds contain double or triple bonds
Alkynes Naming Alkenes and Alkynes
Carbon-carbon triple bonds When the carbon chain has 4 or more C atoms, Names end in -yne number the chain to give the lowest number to the double or triple bond. HC≡CH ethyne(acetylene) 1 2 3 4
CH2=CHCH2CH3 1-butene HC≡C-CH3 propyne CH3CH=CHCH3 2-butene
CH3C≡CCH3 2-butyne
Learning Check HA3 Solutions HA3
Write the IUPAC name for each of the following Write the IUPAC name for each of the following unsaturated compounds: unsaturated compounds:
A. CH3CH2CH=CHCH3 2-pentyne A. CH3CH2C≡CCH3 CH3 CH3 CH3 CH3
B. CH3C=CHCH3 C. B. CH3C=CHCH3 C.
2-methyl-2-butene 3-methylcyclopentene
9 Calling names Hydrogenation Adds a hydrogen atom to each carbon atom of a •ALKANES double bond
•ALKENES H H H H + Ni •ALKYNES H–C=C–H H–C–C–H
•CYCLO- H H H H
•ALKYL- ethene ethane
Products of Hydrogenation Figure 22.11: The structure of benzene
Adding H2 to vegetable oils produces compounds with higher melting points
Margarines
Soft margarines
Shortenings (solid)
Compounds containing aromatic rings Figure 22.12: Some selected substituted benzenes and are often used in dyes, such as these for their names sale in a market in Nepal
Source: Getty Images
10 Bonding in ethane Bonding in ethylene
Bonding in acytylene Cis and Trans Isomers
Double bond is fixed Cis/trans Isomers are possible
CH3 CH3 CH3
CH = CH CH = CH
cis trans CH3
Vision begins with a light induced cis-trans isomerization reaction of retinal
11 isomers STEREO-ISOMERS
• Structural – chain butane Non-Superimposable Mirror Images methyl propane
• Structural - position 2methylhexane 3methylhexane • Structural – function cis • Stereo - geometrical trans
• Stereo - optical
12 COOH COOH COOH
HO CCH H OH
H CH3 CH3 HO CH3 lactic acid
Electromagnetic Radiation
(b)
Figure 20.13: Unpolarized light consists of waves vibrating Figure 20.14: Rotation of the plane of in many different planes polarized light by an optically active substance.
13 Optical Isomer and Interaction with Light Enatiomers rotate the plane of polarized light.
Dextrorotatory- “d” isomer Complex which rotates plane of polarized light to the right. Levorotatory- “l” isomer Complex which rotates plane of polarized light to the left. Chiral molecules are optically active because effect on light
Polarizing sun glasses reduce glare of polarized reflections from surfaces
14