Nomenclature of Organic Compounds Nomenclature of Aliphatic/Acyclic compounds

Line-Angle Formula (Skeletal Structure or Stick Figure): Very handy for writing organic structures, mostly for cyclic compoounds. atoms are assumed to be present wherever two lines meet or a line begins or ends. N, O, X, S (heteroatoms) are shown while C, H are not shown. H is shown onto a heteroatom.

O O CH3 C NH NH CH OH OH CH CH H3C = CH3 C CH3 H3C CH3

Alkanes Rule: Longest continuous carbon chain bearing maximum number of branches, numbered in the direction in which any branch is met first (Lowest Set of Locant Rules). Name of alkyl branches written first with alphabetic order followed by Word Root + ane(primary suffix). The first letter of the complex branch is considered for alphabetic ordering. For simple branch the multiplying prefixes di-, tri-, tetra- are not considered for alphabetic ordring. Complex branches are multiplied with the prefix bis, tris, tetrakis, pentakis etc. Locants are separated by commas and no space in between branches and parent alkane. If the set of locants is same from both side, then the alphabetically senior branch gets the lower locant.

branches + alk + ane Examples: Lower Set of Locants Rule:

CH3 CH3 7 5 2 4 CH CH 8 6 CH2 CH2 1 3 CH2 CH2 4 CH 5 CH H3C CH CH 3 H3C CH CH 3 3 1 6 8 CH3 CH3 CH2 2 CH3 CH2 7 CH3 CH2 CH2

4-ethyl-6,7-dimethyloctane(wrong) 5-ethyl-2,3-dimethyloctane(correct)

CH3

2 4 6 8 10

1 CH2 3 CH 5 CH2 7 CH2 9 CH3 9 7 5 3 1 H3C CH CH2 CH2 CH 10 8 6 4 2

CH3 CH3 3,4,9-trimethyldecane (wrong) (not lower set: begininng with 3) 2,7,8-trimethyldecane (correct) (Lower set: beginning with 2)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Same Set of Locants: Alphabetic Serniority:

CH3 3-methyl-4-ethylhexane (wrong) 5 CH2 1 3 3-ethyl-4-methylhexan (correct) CH2 4 CH 2 CH3 2' 6' 6 CH 4' H3C 3' CH2 1' 5' CH3

Branching Rule:

CH3 CH3 2 4 6 2 4 CH 7 CH 1 3 CH2 CH2 1 3 CH2 CH2 5 CH 5 CH H3C CH CH 3 H3C CH CH 3 6 CH3 (wrong) CH3 (correct) CH CH 7 CH3 CH3 CH3 CH3

2,3-dimethyl-5-propan-2-ylheptane(wrong) 5-ethyl-2,3,6-trimethylheptane(correct) The first one violates the branching rule. In 2nd one, the longest chain has largest number branches attached to it.

8' 7' CH3 H C CH CH 8 3 2' 3 2 4 6 CH3 7 CH CH 5 CH 1' 3 CH H 3 C CH CH 2 C CH3 CH3 H C 3 1 CH3 CH3

6-ethyl-2,2,4,5-tetramethyl-3,7-bis(propan-2-yl)octane N.B: propan-2-yl is a complex branch to be discussed below. Line Structure of Alkanes:

1 H3C 2 CH3 CH CH3 7 3 5 CH3 CH 4 CH 6 CH2 8 = CH2 CH CH CH3 CH2 CH3 CH3

3,4-diethyl-2,5,6-trimethyloctane SAQ I. 1: Give the IUPAC names of the following:

CH3 CH2 CH3 H3CCHCH2 CH3 CH CH CH CH3 3 CH2 (i) H3C CH (ii) (iii) H3CC CH3 CH3 CH2 CH3 CH3 Dr. S.S.Tripathy Nomenclature of Organic Compounds

CH3 H3C CH CH3 3 CH3 CH3 CH CH2 H CCCH H CC CCH (iv) (v) 3 3 (vi) 3 3 H3C CH CH CH3 CH3 CH3 CH2 CH2 CH3

(vii) (viii)

SAQ I.2: Give the structural formula of the following compounds. (i)2,3-dimethylpentane (ii)3-methylhexane (iii)2,2,4-trimethylhexane (iv)2-methylpropane SAQ I.3: Some incorrect names are given. Write the structure of alkanes from them. Also give the correct names. (i)3-methylbutane (ii)2-ethylpropane (iii)4,5-dimethylhexane

Naming a complex branch: Latest Rule: Numbering made from one terminal to the other giving lower locant to -yl. When locant of -yl is 1, then the suffix ‘ane’ is replaced by ‘yl’ and the loacnt 1 is dropped. For example, propyl, butyl, etc instead of prop-1-yl, but-1-yl. Simple alkyl groups like methyl, ethyl, propyl, butyl in which the locant of -yl is 1 are called simple branches. All other alkyl branches containing subbranches of simple alkyl groups like 2-methylpropyl or having locant of -yl other than 1 like propan-2-yl etc. are considered as complex branches. The first letter of the complex branches is considered for alphabetic numbering which includes di-, tri-etc. Such branches are multiplied by the prefixes bis, tris, tetrakis etc. When locant of ‘yl’ is not 1, then letter ‘e’ of ‘ane’ is replaced by ‘yl’,with the locant of ‘yl’ prefixing it. For example propan-2-yl etc.

3 2 3 2 1 CH3 CH CH3 CH2 CH2 1 CH 3 propyl propan-2-yl

4 3 2 4 3 2 1 CH3 CH2 CH CH3 CH2 CH2 CH2 1 CH3 butyl butan-2-yl

1 CH CH3 3 CH3 3 1 3 3 2 2 1 2 CH CH CH CH C CH CH3 C 3 2 3 2 CH CH3 2-methylpropyl 3 2-methylpropan-2-yl 2,2-dimethylpropyl

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Old Rule: The carbon atom of the alkyl branch directly bonded to the principal carbon chain is numbered 1’ to find the longest chain. Ultimately prime over the locant is dropped once it is put insidie parenthesis.

CH CH CH 3 3 3 2' 1' CH3 C CH3 CH CH3 CH2 CH 2' 1' 3' 2' 1' CH3 1-methylethyl 1-methylpropyl 1,1-dimethylethyl isopropyl(propan-2-yl) sec-butyl(butan-2-yl) tert-butyl(2-methylpropan-2-yl)

CH3 CH3 3' 2' 1' CH3 C CH2 CH3 CH CH2 3' 2' 1' CH3 2- methylpropyl 2,2-dimethylpropyl isobutyl neopentyl 2-methylpropyl and 2,2-dimethylpropyl remain the same for both old and new conventions.

N.B: Many text books still use the old convention of naming a complex alkyl branch(1,1-dimethylethyl). The names like isobutyl, isopropyl, sec-butyl, tert-butyl, neopentyl are also used in some texts in IUPAC naming. So the student should not take much critically on this aspect. Remember that a structure can have more than one IUPAC names out of which one is PIN(Preferred IUPAC Name) as per the latest conventions but one name can have a unique structure. Two branches having same initial words: When two groups have same initial words(or letters), the longer branch gets the higher locant. Beween methyl and methylpropyl the former gets a lower locant.

3' 1' 2 4 2' 10 12 3 5 1 6 7 8 2' 9 1' 3' 11

6-methyl-8-(2-methylpropan-2-yl)-5-(2-methylpropyl)dodecane (latest) 8-(1,1-dimethylethyl)-6-methyl-5-(2-methylpropyl)dodecane (old) 8-(tert-butyl)-5-isobutyl-6-methyldodecane (old) If you write according to old system, then for complex branch the prefixes di-, tri- are considered for alphabetic ordering as in the new convention. Using the common names of the alkyl groups, the prefix tert- and sec- are not considered while the prefixes iso and neo are considered for alphabetic ordering.

3'

1' 2' 2 4 10 12 3 5 1 6 7 8 9 11 6,6-bis(2,2-dimethylpropyl)dodecane 2' 1'

3' A complex branch has to be multiplied with the prefixes bis, tris etc. (not di, tri etc.) Dr. S.S.Tripathy Nomenclature of Organic Compounds

SHORT REPRESENTATIONS OF SOME COMMON ALKYL GROUPS: The following abbreviations are used for the alkyl groups written against their names. methyl Me isobutyl i-Bu ethyl Et sec-butyl s-Bu n-propyl n-Pr tert-butyl t-Bu isopropyl i-Pr n-butyl n-Bu SAQ I.4: Give the IUPAC names of the following compounds shown in line drawings.

(i) (ii)

(iii) (iv)

(v) (vi)

(vii) (viii)

(Rule for naming compound (viii): When two or more longest chains containing same number of branches and same set of locants for the branches compete with each other, IUPAC recommends that the longest chain which contains greatest number of carbon atoms in the branches is correct.

(ix) (ix) (x)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

(xi) (xii)

(xiii)

SAQ I.5: Draw the line structures for the following molecules. (i) 5-(2-methylpropy)dodecane (ii) 4-(propan-2-yl)-4-propylnonane (iii) 5-(butan-2-yl)-5-(propan-2-yl)decane (iv) 4,4-bis-(2-methylpropan-2-yl)heptane (v) 3-ethyl-6-(5-methylhexan-3-yl)-8-(propan-2-yl)undecane Answers to SAQs

SAQ I.1 (i) 2,3-dimethylpentane(ii)3-methylpentane

5 CH3 4 CH CH3 3 (iii) H3CC CH3 3,3,4-trimethylpentane(wrong); the set of locants =3,3,4 which is higher 1 2 CH2 CH3 2,3,3-tripmethylpentane(correct) , The set of locants 2,3,3 is lower and is correct.. 1 7 CH3 7 CH3 H3C H3C 2 6 CH 6 CH3 3 CH CH CH2 CH2 1 3 3 5 5 (iv) CH (correct); H C 2 CH (wrong) H3C 4 CH 3 4 CH CH2 CH CH2 CH2 CH3 CH2 3 The second one is violating the branching rule. In the first, there are more number of branches attached to the main chain. Count for yourself to verify. Name: 3-ethyl-2,5-dimethylheptane. The reverse direction of numbering would have given a higher set of locants: 5-ethyl-3,6-dimethylheptane which is wrong.

CH3 1 2 3 H CCCH (v) 3 3 ; 2,2-dimethylpropane (same name if we reverse the numbering) CH3

CH3 CH3 1 2 3 4 H CC CCH (vi) 3 3 ; 2,2,3,3-tetramethylbutane(same name on reverse numbering) CH3 CH3

Dr. S.S.Tripathy Nomenclature of Organic Compounds

CH3

8 6 4 2

(vii)H3C 7 5 3 ; 5-methyl-4-propylnonane (reverse numbering would have given the 9 CH3 1

CH3 set of locants 5,6 which is higher) (viii) 5-ethyl-6,7-dimethyl-4-propyldecane (The set of locants are same on either side. Hence lowest locant is given to alphabetically seniormost branch ethyl by numbering from left to right). SAQ.I. 2: While writing the structure of a compound from its name, first look to the word root of the parent alkane. In this case it is alk(e.g pent-, hex-, but- etc.). First draw a carbon chain containing the required number of carbon atoms in straight chain. Let us take the first bit. (i) The parent alkane is pentane. So let us first draw: C-C-C-C-C. Then number them from one end to the other end. Attach the (branches) at the appropriate carbon atoms.

1 2 3 4 5 CCCCC

CH3 CH3 Then attach the required number of hydrogen atoms to each carbon atom of the main chain bearing in mind that the valency of carbon is 4.

1 2 3 4 5 CH3 CH CH CH2 CH3

CH3 CH3

2 3 4 56 CH3 CH2 CH CH2 CH2 CH3 (ii) CH3

CH3 1 2 3 1 2 3 45 6 CH3 CH CH3 CH3 CCH2 CH CH2 CH (iii) 3 (iv) CH CH3 CH3 3 SAQ I. 3: 1 2 3 1 4 2 CH3 CH CH3 CH3 CH2 CH CH3 (2-methylbutane) 3 (i) (ii) CH2 (2-methylbutane) CH3 4 CH3

6 5 4 3 2 1 CH3 CH2 CH CH CH CH3 (iii) (2,3-dimethylhexane) CH3 CH3

SAQ I.4: (i) 4-ethyl-2-methyl-5,6-dipropylnonane (ii) 3,6,8-triethyl-2,4-dimethyl-6-propylundecane (iii) 5-(pentan-3-yl)decane (PIN); 5-(1-ethylpropyl)decane (iv) 6-(3-methylbutyl)-5-(2-methylpropyl)undecane (v) 2,3,5-trimethyl-4-propylheptane

Dr. S.S.Tripathy Nomenclature of Organic Compounds

(vi) 2,5-dimethyl-4-(2-methylpropyl)heptane (vii) 7-(2-methylhexan-2-yl)-7- (2-methylpentan-2-yl)tridecane (PIN) OR 7-(1,1-dimethylbutyl)-7-(1,1-dimethylpentyl)tridecane (viii) 7,7-bis(2,4-dimethylhexyl)-3-ethyl-5,9,11-trimethyltridecane (ix) 6-ethyl-2,4-dimethyl-5-(2-methylpropyl)-3-(propan-2-yl)octane (PIN) OR 6-ethyl-2,4-dimethyl-3-(1-methylethyl)-5-(2-methylpropyl)octane (x) 2,3-dimethyl-5-(propan-2-yl)octane(PIN) OR 2,3-dimethyl-5-(1-methlethyl)octane (xi) 3,6-dimethyl-5-(3-methylbutan-2-yl)-7-(propan-2-yl)decane (PIN) 5-(1,2-dimethylpropyl)-3,6-dimethyl-7-(1-methlethyl)decane (xii) 4-(2,2-dimethylpropyl)-9-ethyl-2,2-dimethyl-6,6-bis(2-methylpropan-2-yl)undecane(PIN) 6,6-bis(1,1-dimethylethyl)-4-(2,2-dimethylpropyl)-9-ethyl-2,2-dimethylundecane (xiii) 6-methyl-5-(3-methylbutan-2-yl)decane(PIN) OR 5-(1,2-dimethylpropyl)-6-methyldecane

SAQ I.5:

H3C CH3 CH3 H3C H3C

CH (i) 3 (ii)

CH3

CH3 CH3

CH CH3 H3C 3 H3C CH3 CH3 H3C (iii) (iv)H3C CH3 H3C CH3 H3C CH3 CH3

H 3 C CH3

CH3

H 3 C

(v) CH3 H 3 C

CH3

CH3

Dr. S.S.Tripathy Nomenclature of Organic Compounds & Rules Old: CC/ CC should be a part of principal carbon chain even if it may not be the longest chain. Locant of ‘ene’/ ‘yne’ should be least. In case of tally, the LSL(lower set of locants) rule for branches come into force. Branches + Word Root + primary suffix(ene/yne)

1

5CH2 4 2 (2-ethyl-3-methylpent-1-ene) H3C C CH2 4 3 2 5 CH2 CH (not 4-ethyl-3-methylpent-4-ene) 3 CH3 1 CH3

CH3 2 4 6 (2-methylhex-3-ene) CH CH3 1 CH 5 3 3 5 1 (not 5-methylhex-3-ene H3C CH CH2 6 4 2

CH3 1 2 3 4 HC C C CH 3 3,3-dimethylbut-1-yne (not 2,2-dimethylbut-3-yne) CH3

6 CH CH3 3 4 3 5 2 1 2,2,5-trimethylhex-3-yne CH CCC CH3 NOT 2,5,5-trimethylhex-3-yne

CH3 CH3

SAQ Write the IUPAC names from the following line structures.

(i) (ii)

Answer: (i) 6-(butan-2-yl)-3-(propan-2-yl)-2,2,7-trimethylnon-4-yne (ii) 3-ethyl-8-methyldec-5-yne(ethyl gets precedence over methyl due to alphabetical seniority of the former) NEW:

Longest continuous carbon chain to be taken as parent hydrocarbon. This may or may not include CC/

CC. If CC/ CCis not included, the parent becomes alkane. In such case, the branch containing

CC/ CCare written along with other alkyl branch in alphabetic order.

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Naming branch containing CC/ CC: Monvalent alkenyl and alkynyl group: The letter ‘e’ of ene/yne is replaced by ‘yl’. It becomes alkenyl or alkynyl. Note that ‘en/yn’ has its locant and ‘yl’ also has its locant. If the locant of ‘yl’ is 1, then it is dropped. According to new convention, the branch is numbered from one terminal to another like a complex alkyl group. However, the old rule is still followed by some text books in that the carbon atom bonded to the longest chain is numbered 1. See the following examples.

1 3 2 1 3 2 1 CH2 CH CH2 CH CH2 CH3 CH CH ethenyl or vinyl prop-2-en-1-yl or allyl prop-1-en-1-yl or prop-2-enyl or prop-1-enyl

3 2 5 4 3 2 CH3 C CH3 CH CH CH

1CH2 1CH3 prop-1-en-2-yl but-3-en-2-yl (1-methylethenyl) (1-methylbut-2-enyl)

HC C HC C CH2 H3CC C ethynyl prop-2-yn-1-yl prop-1-yn-1-yl or prop-2-ynyl or prop-1-ynyl Bivalent alkylidene group: If =C- is directly bonded to the longest chain, then the group is bivalent. In that case, a suffix ‘idene’ is to be used with the respective ‘alkyl’ group. alkyl + idene = alkylidene alkyl - alkylidene

CH3- () CH2= (methylidene group)

CH3-CH2-(ethyl) CH3CH= (ethylidene)

CH3-CH2-CH2-(propyl) CH3-CH2-CH= (propylidene)

H3C H3C CH (propan-2-yl/isopropyl C (propan-2-ylidene/isopropylidene) H3C H3C

Naming bivalent group contianing one more CC/ CC: alkenyl + idene = alkenylidene alkynyl + idene = Alkynylidene

H3C CH CH CH (but-2-enyl) H3C CH CH CH (but-2-enylidene)

CH C CH (prop-2-ynylidene) SAQ : Write the names of the following groups.

H3C CH3 CH2 CH C CH CH CH2 CH (i) (ii) (iii) H3CC CCH CH3 H3C

Dr. S.S.Tripathy Nomenclature of Organic Compounds

H C CH3 H CCCH 3 3 CH CCCH2 (iv) (v) (vi) H2CCCH CH2 (vii)CH =C= CH3 H C 2 3 CH3

(viii) CH3CH(CH3)CH(CH3)CH= (ix) CH3CH2C(CH3)= Answer:

(i) 3-methylbutylidene (ii)2-methylpent-2-enylidene (iii)but-2-ynylidene (iv)2-methylprop-1-enyl (v)4-methylpent-2-ynyl (vi)2,3-dimethylbut-3-enyl (vii)ethenylidene(vinylidene) (viii) 2,3-dimethylbutylidene (ix) butan-2-ylidene

Naming Alkenes and Alkynes according new rule:

8 6 4 2

7 5 3 H3C CH3 CH3 9 1

1 2 4 6 8 2 3 5 7 H3C CH3 1 9 CH 3

CH2 2-methyl-7-methylidenenonane(new name) 5-(prop-2-ynyl)nonane( new name) 2-ethyl-7-methyloct-1-ene(old name) 4-butyloct-1-yne(old name) SAQ : Write the names of names of the following alkenes and alkynes on the basis of the new rules. Compare the names with those obtained by using old rules.

CH CH3 3

CH3 CH3 H C (i) H3C CH3 (ii) 3

CH3 CH3 CH 3 H3C

H3C

CH3 (iii) CH CH3 Answer: (i) 3,4-diethyl-5-methylhept-2-ene(same according both the rules as the C=C bond is included in the longest chain) (ii) 4-ethyl-2,7-dimethyl-5-propylidenenonane(new); 5-ethyl-7-methyl-4-(2-methylbutyl)oct-3-ene(old) (iii) 3-ethyl-5-ethynyloctane(new); 5-ethyl-3-propylhept-1-yne(old)

Dr. S.S.Tripathy Nomenclature of Organic Compounds Haloalkanes(Alkyl Halides) Rule: The halo group(-X) may or may not be directly bonded to the longest carbon chain. If it is not directly bonded, then it is part of a complex alkyl group with a halo subbranch. The naming is done just like any alkane. Halo bearing group competes with other alkyl groups for alphabetical seniority.

1 2 3 4 5 H3CCHCHCH2 CH3 : 3-bromo-2-methylpentane(not 3-bromo-4-methylpentane) CH3 Br

Br H3C

6 4

H3C 5 3 7 CH3 CH 3 2

H3C CH3 1 4-(2-bromoethyl)-3-ethyl-2,5,6-trimethylheptane

In the above example, Br- is a part of a complex group bromoethyl. SAQ : Give the IUPAC names from the following line structures

ClCH3 Br

(i) (ii) (iii)

Cl H3C CH3 I

Asnwer: (i) 4-(butan-2-yl)-3-chloro-5-methylheptane (ii)4-ethyl-5-iodomethyl-2-methylheptane (iii) 2-bromo-6-chloro-4-methylheptane

Functional Groups having Secondary Suffixes: (Naming multifunctional compounds)

The following table gives the functional groups and their suffixes which are used after primary suffix.

Branches(Prefixes)+Word Root + primary suffix + secondary suffix

Word Root: meth(1), eth(2), prop(3), but(4), pent(5), hex(6), hept(7), oct(8), non(9), dec(10), undec(11), dodec(12), tridec(13), tetradec(14), pentadec(15), hexadec(16), heptadec(17),.. icos(20), henicos(21), docos(22), tricos(23), tetracos(24), pentacos(25).... triacont(30), hentriacont(31), dotriacont(32), tritriacont(33), tetratriacont(34)...... tetracont(40), hentetracont(41),dotetracont(42), tritetracont(43)...... pentacont(50), henpentacont(51),dopentacont(52)...... , hexacont(60), henhexacont(61), dohexacont(62)....., heptacont(70), henheptacont(71), doheptacont(72)...... octacont(80), henoctacont(81), dooctacont(82)...... nonacont(90), hennonacont(91), dononacont(92)...... hect(100), henihect(101), dohect(102), trihect(103), tetrahect(104).....decahect(110), undecahect(111), dodecahect(112)...... icosahect(120).....

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Primary suffix : ane/ene/yne

1. If there will be at least one C=C or CC, then primary suffix ‘ane’ is not used. In stead ‘ene’ or

‘yne’ is used. If there are more than one C=C or CC, then di-, tri- etc. are used as prefix to ‘ene’, ‘yne’. In such case, the letter ‘a’ is suffixed to the Word Root (alk) to maka it alka (eg buta, penta, hexa etc.). For example buta-1,3-diene(not but-1,3-diene). 2. C=C or CCcan be used as primary suffix as ‘ene’ or ‘yne’ along with the secondary suffix of the seniormost functional groups. They can also be used in a branch with the name alkenyl, alkynyl, alkylidene, alkenylidene or alkynylidene etc. 3. The following table gives the functional groups with decreasing priority order for which secondary suffix is used. These are called Type C groups which can both be used as suffix or as prefix(branches).

Type C functional Groups: Name of group structure prefix suffix

O -oic acid C OH carboxy (carboxylic acid)

-SO3H sulfo sulfonic acid

O O acid anhydride C OC - -oic anhydride

O alkoxycarbonyl -oate C OR' (carboxylate)

O -oyl halide acid halide halocarbonyl C X (carbonyl halide)

O acid -amide C NH2 aminocarbonyl (carboxamide)

- nitrile CN cyano (carbonitrile)

O -al oxo C H (formyl) (carbaldehyde)

O C oxo -one alcohol -OH hydroxy -ol -SH sulfanyl/mercapto -thiol

-NH2/-NHR/-NR2 amino - ______Deletion of ‘e’: If the secondary suffix begins with any vowel such as ‘a, y, i, o, u’ then the letter ‘e’ to be deleted from prmary suffix ane/ene/yne. For example butanol, pentanone, but pentanenitrile. (NB: For acquainting with the IUPAC naming compounds containing single , please refer e-Concepts in Chemistry for Junior Level: Nomenclature Chapter-II)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Rules: * The LONGEST carbon chain bearing the highest priority functional (type C) group should also bear maximum number of other type C groups. Such group(s) cannot be ignored or be excluded from the longest

chain. Such a chain may exclude C=C or CCif required, if they are not part of the LONGEST chain containing maximum number of type C groups. Conclusion: The longest chain bearing the highest priority group may or may not include other functional groups or C=C/ CC. Betwen any typc C group and C=C/ CC, the former is preferred.

* The one having highest priority among such groups will make the secondary suffix. In other words the parent compound will be named after this. Other such groups will be used as branches(prefixes). For -OH it is hydroxy, for (-C=O) it is oxo and so one. Look to the prefix column for this. The suffix names which are written inside parenthesis below their respective first names are used only when such functional group is outside the principal carbon chain. For example, if -COOH remains within the principal chain, i.e the carboxyl carbon is counted as no. 1, then the secondary suffix ‘oic acid’ is used. If -COOH remains outside the carbon chain, then ‘carboxylic acid’ is used. As a prefix also if -CHO(aldehyde) group remains outside the carbon chain, then ‘formyl’ is used otherwise ‘oxo’ is used. Groups which are used only as substitutents(Prefix): Type A groups Such groups do not have any priority order. All such groups obey LSL rule. Name of the group General formula alkyl R- alkoxy RO- alkylsulfanyl(alkylthio) RS- halo X-

nitro NO2- alkenyl RCHCH

alkynyl RCC

phenyl C6H5- cycloalkyl cyclopropyl, cyclobutyl etc.

(Note that C=C and CCare called Type B functional groups which are used as primary suffix(ene/yne) * Since -COOH and derivatives of -COOH and -CHO are terminal functional groups, the one which has the highest priority among them always gets no. 1 locant. * When –CN is a lower priority group in a molecule, it is never taken inside the principal carbon chain. It is always used as prifix(cyano). Cyanide carbon is never counted in such case.

* In polyene/enynes C=C and CCenjoy the same priority. However in case of tally, ‘ene’ gets the precedence.

CH3 O Cl O

7 5 3 1 6 4 2 H3C OH 8

O OH

N

5-chloro-2-cyano-4-hydroxy-7-methoxy-6-oxooct-3-en-1-oic acid OR 5-chloro-2-cyano-4-hydroxy-7-methoxy-6-oxooct-3-enoic acid

Dr. S.S.Tripathy Nomenclature of Organic Compounds

(locant 1- for terminal functional groups appearing in secondary suffix is deleted).

OH Cl

4 2 H O CH3 5 3 1

O OH O ethyl 4-chloro-3-hydroxy-2-(hydroxymethyl)-5-oxopentanoate

(note that for aldehyde group, we used the prefix ‘oxo’ as it is a part of the carbon chain. For too we shall use ‘oxo’.

HO 6 5 NH2

4 2 OH 3 1

O OH 6-amino-5-hydroxy-4-(2-oxoethyl)hexanoic acid

The longest chain containing more number of functional groups is chosen irrespective their priorities.

NH2 O

O 6 1 OH H O O 5432 6 1 5 4 3 2 NH 2 O NH2 NH 2 H 2-amino-5-methyl-6-oxohex-3-ynamide 2,6-diamino-5-formyl-6-oxohex-3-ynoic acid

In the 2nd case above, amide is senior to aldehyde, hence amide carbon was included in the principal chain. Since -CHO is now excluded from main chain, the prefix ‘formyl’ has been used. Note that for amide group, we used two suffixes, one for -C=O(oxo) and other other for -NH2(amino). functional group two prefixes used amide both amino and oxo (not aminocarbonyl) acid chloride both chloro and oxo (not chlorocarbonyl) ester both alkoxy and oxo (not alkoxycarbonyl)

O H O 4 2 OH 6 2 3 1 5 4 Cl 3 1 CH3O

O O 2-ethyl-4-formylhexanoyl chloride 4-methoxy-2-methyl-4-oxobutanoic acid

Dr. S.S.Tripathy Nomenclature of Organic Compounds

SO3H O O 2 H C 3 5 CH 1 3 4 3 3 1 2 4 6 7 OCH3

4-methoxy-3-methyl-4-oxobutane-2-sulfonic acid Cl Br OH

4-bromo-2-chloro-6-hydroxyhept-5-en-3-one

1' 2 I OH 5 2' 4' H2N 3 1 3 6 4 2 3' 3-aminopropan-1-ol (not 3-hydroxypropan-1-amine 1CN OH

2-(3-hydroxybutan-2-yl)-3-iodo-4-methylhexanenitrile

Br CH3 CH2 O

7 5 3 1

Cl 6 4 2 2-bromo-5-chlorohexane H3C OH 2-chloro-5-bromohexane(wrong) 8

7-methyl-5-methylideneoctanoic acid old: 5-(2-methylpropyl)hex-5-enoic acid)

CH2 CH2

HO 6 4 2 OH 2 O CH H3C 4 3 7 5 6 3 1 5 3 1

CH3 O O propan-2-yl 2-(prop-2-enylidene)hex-4-enoate 7-hydroxy-4-methylideneheptanoic acid old: 1-methylethyl 2-(but-2-enyl)penta-2,4-dienoate old: 4-(3-hydroxypropyl)pent-4-enoic acid

O

5 3 1 CHO 1CN 4 2 O H3C OH 6 7 6 5 4 3 2 COOEt CH3 C CH C C CH CH2 CH3 2-ethyl-5-formyl-6-oxohept-3-ynenitrile 4-(ethoxycarbonyl)hexanoic acid

4 6 4 2 3 2 1 OH 5 3 1 O N C CN O O 4-cyano-2-methylbutanoic acid sec-butyl 5-cyano-2-methylpentanoate

Dr. S.S.Tripathy Nomenclature of Organic Compounds

1 4 2 CN COOEt 1 OH 3 4 2 NC 3 O 5

4-cyano-2-methylbutanoic acid Ethyl 4-cyano-2-ethyl-3-methylpentanoate

CH3 CH3 CH O O CHO O 7 5 3 C 2 EtO 4 1 6 OH COOEt

ethyl 6-methyl-7-oxo-4-(propan-2-yloxy)hept-4-enoate 7-ethoxy-7-oxoheptanoic acid

O O O 3 5 7 5 3 CH3 C1 C 6 8 6 4 2 1 CH O EtO OH 2 4 CH3 C 7 8 O NH2 6-(ethoxycarbonyl)oct-7-enoic acid propan-2-yl 6-(aminocarbonyl)octanoate

Polyenes/Polyyenes/enyes:

In this case, longest chain is the key. That chain can bear C=C, CC, then its preferred. Such longest chain should bear maximum number of multple bonds, but not at the cost of chain length.

5 7 3 1 3 9 5 1 11 6 2 4 6 10 8 4 2 (I) (II) 3-methylhex a-1,4-diene 5-ethyl-7,9-dimethylundeca-4,6-diene

4 2 1 2 2 3 5 3 1 6 4 1 4 7 5 3 6 (IV) (V) (III) 4-isopropyl-6-methyl-3-propylhept-5-en-1-yne but-1-en-3-yne hexa-1,3-dien-5-yne

[Please read 4-(propan-2yl) for 4-isopropyl in (III) of the above structures and put it after 6-methyl. Isopropyl can be used but it is now not PIN].

Dr. S.S.Tripathy Nomenclature of Organic Compounds

7 5 3 2 6 2 8 4 4 5 3 9 7 6 1 1

6-ethyl-3,7-dimethyl-4-methylidenenon-2-ene 4-(ethenyl)hep-5-en-1-yne old: 2-(2-ethyl-3-methylpentyl)-3-methylpenta-1,3-diene (In the last structure ‘e’ has been deleted from ‘ene’ as ‘y’ is facing it. ‘en’ is always written first even though its locant is higher)

H3C 6 5 7 CH2 2 4 2' 45 1 3 1' 3' 6 7 23

H2C 8 9 CH 1 10 4-(prop-1-enyl)hepta-1,4-diene 7-ethenyl-5-ethylidenedec-1-en-9-yne

2

3 CH CH3 1

6 H3C 4 6 8 7 5 7 CH3 543 9

2 CH3 CH2 1 H2C H3C CH 3-ethenyl-3-ethynyl-2-methylheptane 5-(prop-2-ynylidene)-4-vinylnona-2,7-diene Old: 4-(2-methylpropyl)-4-propylpent-1-en-4-yne 4-(but-2-enyl)-5-ethenylocta-3,6-dien-1-yne

Compounds containg idential functional groups: In such case, the secondary suffix is prefixed with di-, tri- etc. For example, diol, trione, dial etc. In such case the ‘e’ of primary suffix is not dropped. Rule: The principal chain should bear maximum number functional groups.

Br OH OH OH 1 3 5 3 OH OH 2 4 6 2 4 OH CH2 CH CH2 CH CH 2 2 OH OH 1 OH ethane-1,2-diol propane-1,2,3-trio 2-butylbutane-1,4-dio (ethylene glycol) 5-bromohexane-2,4-diol (glycerol)

OH

1 2 2 4 6 CH3 8 5 3 CH 3 5 7 3 H3C 4 1 H3C 6

OH OH NH2 NH2 CH3 3-(1-hydroxyethyl)hexane-1,4-diol

7-methyloctane-3,5-diamine Dr. S.S.Tripathy Nomenclature of Organic Compounds

CH3 10 CH3 9 CH3 8

7 5 3 CH3 O 6 H C 4 2 1 3 3 5 6 H3C CH3 12 4 O O O O 3-ethyl-5-methylhexane-2,4-dione 5-(1-oxoethyl)decane-2,7-dione

O O O O O O

HC C H HCCH2 C H HCCH2 CH2 C H ethanedial propanedial butanedial (oxalaldehyde) (malonaldehyde) (succinaldehyde)

O O HO OC COOH HOOC COOH HOCC OH CH 2 CH2 CH2 ethanedioic acid propanedioic acid butanedioic acid (oxalic acid) (malonic acid) (succinic acid)

5 HOOC(CH2)3COOH 1 COOH COOH (pentanedioic acid/glutaric acid) 2 4 3 HOOC(CH2)4COOH (hexanedioic acid/adipic acid) 2-ethyl-4-isopropylpentanedioic acid

1 O H2N 4 O O 2 3 3 1 5 4 O 5 2 O 6 O NH2 2-ethyl-5-methylhexanediamide diisopropyl 2-methylpentanedioate (Please read di(propan-2-yl) for diisoprpyl)

H3C CH3

CH3

O O CH3

O O 1-ethyl 5-isopropyl 2-methylpentanedioate

2 4 Cl Cl 6 1 3 5 NC 4 2 5 3 1 CN O O 3-ethyl-2-methylpentanedioyl dichloride 2,4-dimethylhexanedinitrile

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Compound containing 3 or more identical carbon-bearing terminal functional groups : Case-I If the 3rd group is directly bonded to the principal chain containing two groups, then all the three are not included for the parent carbon chain. In such case, the following suffixes are used after alkane.

alkane tricarboxylic acid(acid); trialkyl alkanetricarboxylate(ester); alkane tricarbaldehyde(aldehyde); alkanetricarbonitrile(nitrile); alkane tricarboxamide(amide); tricarbonyl trichloride(acid chloride)

OCH2CH3 OH O O O O O 2 4 2 3 1 3 1 OCH CH OH CH3CH2O 2 3

4 5 HO O butane-1,1,2-tricarboxylic acid triethyl pentane-1,2,3-tricarboxylate

OH CN CH3 6 OCl H O 3 5 H3C 2 2 4 Cl 1 Cl O 3 1 H 1 CN propane-1,2,3-tricarbaldehyde CN O O methanetricarbonyl trichloride 2-methylhexane-1,3,4-tricarbonitrile

Case-II: If the 3rd group is not directly bonded to the carbon chain, then two groups in the chain are included in the principal chain, the third becomes subbranch of an alkyl branch eg. carboxymethyl, amioncarcarbonylmethyl etc.

1 3 HOOC 5 7 4 2 5 2 4 COOH 3 1 6 CN CN

CN COOH 4-carboxymethylheptanedioic acid 3-cyanomethyl-2-methylpentanedinitrile

3' 2' COOCH2CH3 CHO 1' 2' 1 1' 3 5 OHC 6 1 7 2 4 3 5 CHO CH3CH2OOC 2 4 6 8 COOCH2CH3 2-methyl-3-(2-oxoethyl)hexanedial diethyl 3-methyl-5-(3-ethoxy-3-oxopropyl)octanedioate SAQ: Give the IUPAC names of the following compounds from their line structures.

OH O (i) (ii) (iii) OH COOH

O NH2 SO3 H O

(iv) Cl (v) H (vi) OH Br OH CN

Dr. S.S.Tripathy Nomenclature of Organic Compounds

COOH O O H C CH3 3 CH3 Cl (vii) H3C O (viii) CH3 SO H CHO 3

HS OH OH SNH (ix) (x) 2 (xi) H

CH3 CH3 OH

H3C CH3 H C SCH 3 (xii) 3 (xiii) OH O CH3 O

CH3 O CH3 H C (xiv) 3 (xv) O OH H C CH 3 3 CHO

Asnwer: (i) pent-4-en-2-ol (ii) 2-methylhex-3-ynoic acid (iii) 5-hydroxyhexan-3-one (iv)3-amino-2-bromo-5-chloroheptan-4-ol (v) 2-methyl-5-oxopentanenitrile (vi)2-methyl-3-sulfobutanoic acid (vii) 7-tert-butoxy-6-formyl-3,5-dimethyl- 7-oxohept-4-enoic acid (viii) 6-chloro-4-methyl-6-oxohex-1-yne-3-sulfonic acid

(ix) 2-(prop-1-enyl)hexan-1-ol(new); 2-butylpent-3-en-1-ol(old) (x) 3-aminopropane-1-thiol (xi) 4-sulfanylbutan-2-ol (4-mercaptobutan-2-ol) (xii)7-(propan-2-ylthio)octan-4-ol (xiii) 7-oxo-4-(prop-1-enyl)octanoic acid(new);4-(3-oxobutyl)hept-5-enoic acid(old); (xiv)3-(but-1-enyl)-6-ethyl-7-methyloctan-2-one(new); 3-(3-ethyl-4-methylpentyl) hept-4-en-2-one(old) ; (xv) 4-formyl-5-phenylhept-2-enoic acid SAQ: Write the IUPAC names of the following compounds.

H3C CH3 HC CH CH2

H3C CH2 (i)H3C (ii)

CH 3 H2C H3C

Dr. S.S.Tripathy Nomenclature of Organic Compounds

H3C CH2

CH3 CH3

H2C (iii)

CH

CH3 H3C CH3

CH3

CH2 H3C CH (iv) 2 (v) H3C CH3 CH3

CH3 Answer:

(i) 4-ethynyl-2-methyl-5-(pent-2-en-2-yl)undec-2-en-8-yne (ii) 3-ethynyl-4-methyl-5-methyidenehepta-1,6-diene (iii) 3-ethynyl-4-(prop-1-en-2-yl)-6-methyldeca-1,3,6-trien-8-yne (iv) 4-ethenyl-6-methyl-7-(propan-2-ylidene)undeca-2,5,9-triene (v) 6-ethyl-4-methylidene-5-(prop-1-enyl)dodeca-7,9-dien-2-yne SAQ: Write the IUPAC names of the following.

O NH H2N 2 HO O O O H (i) NH2 (ii) NH2 O O

NH NH 2 2 NH2 NH2

OOOO (iii) (iv)

O O H N O H3C 2

H 2 N O CH OH O O 3

O (v) (vi) O (vii) OO Cl HO OH OH H O O

OOO

NH CH3

H3C CH3 (viii) (ix) H3C NH

CH3

Dr. S.S.Tripathy Nomenclature of Organic Compounds

O

CHO Cl O

H3C (x) (xi) Cl Cl CHO CHO

O

OOCH3

(xii)H3C O O CH3

CH3 Answer: (i) 3-(2-amino-2-oxoethyl)-2,3-dimethylpentanediamide (ii) 3-(2-amino-2-oxoethyl)-6-oxohexanoic acid) (iii) methyl 7-amino-2-(3-amino-3-oxopropyl)-7-oxoheptanoate (iv) heptane-1,3,7-tricarboxamide (v) 4-(aminocarbonyl)-7-oxoheptanoic acid (vi) 9-chloro-5-formyl-6-(methoxycarbonyl)-9-oxononanoic acid (vii) propane-1,2,3-triol(glycerol) (viii) 2-methylnonane-3,5,7-trione (ix) N,N’-dimethylbutane-1,4-diamine (x) pentane-1,1,3-tricarbaldehyde (xi) 3-(2-chloro-2-oxoethyl)hexanedioyl dichloride (xii) 5-ethyl 1-(propan-2-yl) 2-methylpentanedioate (When two alkoxy(OR’) parts of diester are different, each alkyl group is prefixed with the locant of carboxyl carbon to which the is attached)

SAQ: Draw the structures of the following. (i) ethyl 6-cyano-4-methyl-3-methylidenehepta-4,6-dienoate (ii) methanetricarbaldehyde (iii) 2,3,4,5,6-pentahydroxyhexanal (iv) 3-ethenyl-2,3,6-trimethylocta-1,6-dien-4-yne (v) 3-(2-amino-2-oxoethyl)pentanediamide Answer:

CN CH 3 OHC

6 4 2 OCH3 5 3 1 CHO H2C (i) 7 (ii)

CH2 O OHC

OH OH O CH2 7 H3C CH2 8 1 H (iii) (iv) 65432 OH OH OH H3C CH3 CH3

Dr. S.S.Tripathy Nomenclature of Organic Compounds Naming Bivalent and Multivalent Radicals:

Divalent radicals using the suffix ‘idene’ has been already discussed. That is case when one H atom is removed from a monovalent alkyl group. Similarly when two H atoms are removed from a monovalent alkyl group, it becomes a trivalent radical. Trivalent radical: yl of alkyl is suffixed with ‘idyne’.

CH : methyl+idyne = methylidyne CH3 C : ethyl + idyne = ethylidyne Note that these radicals cannot attach with any carbon chain. However such groups are used in complex compounds of metals ions as ligands. Bivalent radicals obtained by removing H atom from the two terminal carbon atoms(two monovalent radicals in one species) of a normal alkane(unbranched)

The suffix ‘ene’ is used after polymethyl : polymethyl+ene = polymethylene

CH2 CH2 tetramethyl+ene = tetramethylene (butylene)

–CH2–CH2– : ethyl + ene = ethylene Similarly hexamethylene, pentamethylene etc. These namings are used in trivial systems, eg. (1) hexamethylene diamine(for hexane-1,6-diamine) (2) ethylene dichloride(1,2-dichloroethane) Multivalent radicals on two terminals : alkane + diyl + idene (if both the terminals are C=) alkane + diyl + idyne (if both terminasl are C ) alkan+yl+ylidene (if one is C– and other is C=) CH CH butane+diyl+idene = butanediylidene

CH CH butane + diyl + idyne = butanediylidyne

CH CH butan-1-yl-4-ylidene Such groups(restricted to divalent on either side) can be used in naming compounds in trivial system eg butanediylidene diimine. However trivalent radicals on either side cannot be used often usually in organic structures.

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Naming of Alicyclic compounds:

cyclopropane cycloprpyl cyclobutane cyclobutyl cyclopentane cyclopentyl

cyclohexyl

Naming aliphatic compounds with cyclic branches:

OH O O

Cl O

5-cyclopropyl-4-oxoheptanoyl chloride 1-cyclobutyl-3-hydroxybutan-1-one

* If the cyclic ring is attached to one carbon atom or one functional group, then the naming should be done as a cyclic compound. In other words, if the higher priority functional group is directly attached to the ring, then it is named as a cyclic compound. * If the cyclic ring is attached to more than one carbon, then it can have two alternative names : (i) as an aliphatic compound with cycloalkyl prefix or (ii) a cyclic compound with aliphatic prefix. The aliphatic name is preferred(PIN)j in such case. See the following examples.

COOH CH2COOH

cyclobutane carboxylic acid 2-cyclopentylethanoic acid(aliphatic name) (not cyclobutylmethanoic acid) carboxymethylcyclopentane (cyclic name)

4 2 3 1 3' 2' OH COOH 2'' 1'' 2 3'' 4' 1' 1 HO CH2 CH2 CH2 CH CH2 OH

3-cyclohexylbutanoic acid 1-[4-(3-hydroxypropyl)cyclohexyl]ethane-1,2-diol Only in case of the 1st compound, the cyclic name is preferred. In all the other three examples, the aliphatic names are preferred as the functional group is not directly bonded to the ring. Dr. S.S.Tripathy Nomenclature of Organic Compounds

Other logic for naming as valid for aliphatic compounds are also valid for ring compounds. After the highest priority group, C=C is considered(not other functional group) for LSL rule.

HO O OH

1 H3C 1 6 2 6 2

5 3 5 3 4 4 cyclohex-2-en-1-ol 6-methylcyclohex-2-ene-1-carboxylic acid

O H O CH3 1 CH3 6 2 1 5 3 2 6 4 3 5 OH 4 4-hydroxy-2-methylcyclohexanone 2-ethylcyclohexanecarbaldehyde

Cl O H2N O

1 1 HO 6 2 6 2

5 3 5 3 4 O 4 5-oxocyclohex-2-ene-1-carboxamide 6-hydroxycyclohex-3-ene-1-carbonyl chloride

O O H3C HO 2 NH2 1 3 HO 1 2 6 6 4 3 5 5 4 O methyl 2-hydroxy-5-oxocyclohexanecarboxylate 3-aminocyclohexanol

NH2 2

1 O OH

2-ethylcyclohexanol ONH2 (2-ethylcyclohexan-1-ol) 2-(8-amino-8-oxooctyl)cyclohexanecarboxamide

COOH OH

cycloprop-2-ene-1-carboxylic acid 3-cyclobutylpropan-2-ol

Dr. S.S.Tripathy Nomenclature of Organic Compounds

NH2 CH3

CH3

H2N CHO 3-methylcyclohexane-1-carbaldehyde OH 1-(2,4-diaminocyclohexyl)propan-1-ol

NH2 OH

CONH2

2-aminocyclopentane-1-carboxamide cyclobut-2-en-1-ol

SAQ : Write the IUPAC names of the following.

H 2N O O O CH3 CH3

OH (i) OH (ii) (iii) O

HO

H 3C

CH3

CH3 H O

(iv) (v)

CH OH 3

CH3

NH2 HO CH3

H 3 C

CH3

(vi) COOH (vii) (viii)

CH3

CH3 Answer: (i) 3-(6-methylcyclohex-1-enyl)propan-1-ol (ii) 3-[2-(aminocarbonyl)cyclohexyl]propanoic acid (iii) 4-(3-formylcyclopentyl)-2-methylbutanoic acid (iv) 1-cyclopentylethanol (v) 2-(2,3-dimethylbutyl)cyclobutanol (vi) 3-(5-hydroxycyclohex-2-enyl)-2-methylpropanoic acid (vii) 2-(2,2-dimethylbutyl)cyclopropanamine (viii) 1-ethyl-2-propylcyclohexane

Dr. S.S.Tripathy Nomenclature of Organic Compounds

AROMATIC COMPOUNDS:

Benzene(C6H6): It is primarily the hybrid of the two resonating structures.(Refer Chemical Bond for details). Benzene and its derivatives are aromatic compounds. Such compounds are unique in their behaviour. They are more stable and hence less reactive than their acyclic analogue hexa-1,3,5-triene apart from having acceptable fragrance(aroma). The details of aromaticity will be discussed later in the chapter aromatic hydrocarbons.

(Resonance Hybrid) Resonating Structures

All the six positions of benzene are equivalent.

CH2 (C6H5–) phenyl (benzyl)

Monosubstituted Benzene:

1 2 Cl OH CH3 NO2 NH2 CHO COOH COCH3

toluene chlorobenzene phenol nitrobenzene aniline benzaldehyde benzoic acid acetophenone (methylbenzene) (hydroxybenzene) (aminobenzene) (1-phenylethanon

OCH O CN COCl CONH2 COONa 3 COOCH3

methoxybenzene benzophenone benzonitrile benzoyl chloride benzamide sodium benzoate methylbenzonate (anisole) (diphenylmethanone)

NO CH2 Cl (nitrosobenzene) chloromethylbenzene biphenyl (benyl chloride)

Cl Cl CCl CH Cl e Cl dichloromethylbenzen trichloromethylbenzen (benzal chloride) (benzotrichloride) If the functional group is not directly bonded to the benzene ring, then the compound is named as aliphatic.

Dr. S.S.Tripathy Nomenclature of Organic Compounds

OH

COOH CH2 OH OH phenylmethano phenylmethanol phenylacetic acid (benzyl alcohol triphenylmethanol

SAQ III.8: Write the IUPAC names of the following compounds.

H3C CH3 CH2CH3 CH COCH2CH3 OCHCH3 COOCH(CH3)2 I

(i) (ii) (iii) (iv) (v) (vi) (vii) Answer: (i) ethylbenzene (ii) isopropylbenzene(cumene) (iii) propiophenone(1-phenylpropan-1-one) (iv) ethoxybenzene (v) isopropylbenzoate (vi) iodobenzene (vii) 1,2,3-trimethylbutylbenzene

SAQ: Write the IUPAC names of the following.

CHO CH 3 H3C

CN Cl NH2 O CH3

(i) (ii) (iii) (iv) (v) CH3 O

Answer: (i) (chloromethyl)benzene(Cl is not a functional group) (ii) 1-phenylmethanamine (iii) methyl 2-phenylacetate(ethanoate) (iv) phenylacetonitrile(phenylethanenitrile) (v) 2,3-dimethyl-3-phenylbutanal Disubstituted Benzene :

X X X 1 1 1 2 6 6 Y 6 2 2

3 5 3 5 3 5 Y 4 4 4 Y 1,2- or ortho 1,3- or meta 1,4- or para

There are three isomers for two substituents namely (i) ortho(1,2) (ii) meta(1,3) (iii) para(1,4). There two equivalent ortho positions with resepct to a particular substitutent on either side of it. Similarly there are two equivalent meta positions for group. But there is only one para position. Naming: Rules: Priority order among Type C groups are the same as for aliphatic compounds.

-COOH >-SO3H > -COOR’ > COCl > CONH2 > -CN > -CHO > -COR > -OH > -NH2 (I) If the comounds has both or at least one Typce C group, then the parent compound is given after the higher priority group, the other one appears as branches(prefixes) see these examples. Dr. S.S.Tripathy Nomenclature of Organic Compounds

NH COOH 2 2 1 CN 3 1 3 HO 2 2 4 1 OHC HO salicylic acid 4-formylbenzonitrile 3-aminophenol (2-hydroxybenzoic (p-formylbenzonitrile) (m-aminophenol) acid/ o-hydroxybenzoic (not 4-cyanobenzaldehyde) (not 3-hydroxyanilin acid)

H3C CH3 N COCH 3 COCH3 OH

SO3H NO2

N,N-dimethyl-4-nitroaniline 3-acetylbenzenesulfonic acid 2-hydroxyacetophenone (II) If both groups belong to type A (not type C), then the alphabetic senior group will get the lower locant.

NO2 4 CH3 2 Cl 1 1 CH 3 CH3 1-chloro-2-methylbenzene(PIN 1-ethenyl-3-methylbenzene(PIN 1-methyl-4-nitrobenzen (3-ethenyltoluene) (2-chlorotoluene) Or, 4-nitrotoluene

OCH3 4 HO 1 1 2 2-(4-aminophenyl)phenol CH2CH3 H2N 1-ethyl-4-methoxybenzene(PIN (4-ethylanisole)

* If aromatic and aliphatic parts contain type C group, then the part bearing higher priority functional group gives the parent name. If idential functional group present in both the parts, then it will be named as aromatic.

CH3 COOH CHO

HOOC H3C HO HO CH3 (4-hydroxyphenyl)acetaldehyde 4-(2,2-dimethylbutyl)phenol 4-(carboxymethyl)benzoic acid

Dr. S.S.Tripathy Nomenclature of Organic Compounds

1 OH OH 2

3

NH 2 phenylmethanol (3-aminophenyl)methanol Identical groups:

OH OH OH COOH OH

COOH OH OH pyrocatechol resorcinol hydroquinone phthalic acid (1,2-dihydroxy (1,3-dihydroxy (quinol/1,4-dihy droxy (benzene-1,2-dicarboxylic benzene/o-dihydroxy benzene/o-dihydroxybenzene/p-dihydroxy acid) benzene) benzene) benzene

CH3 COOH COOH CH3 CH3

CH COOH 3 COOH m-xylene isophthalic acid terephthalic acid o-xylene (1 ,2 -dimethy l (1,3-dimethyl (benzene-1,3- (benzene-1,4- benzene/m-dimethyl dicarboxylic acid) benzene/o-dimethyl dicarboxylic acid) benzene) benzene)

NH2 NH2 CH3 NH2 NH2

NH2

NH2 CH3 p-xylene benzene-1,2-diamine benzene-1,3-diamine benzene-1,4-diamine (1,4-dimethyl (1,2-diaminobenzene/ (1,3-diaminobenzene/ (1,4-diaminobenzene/ benzene/p-dimethyl o-phenylenediamine) m-phenylenediamine) p-phenylenediamine) benzene)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

SAQ III.10: Write any one IUPAC name of the following aromatic compounds.

CH3 COOH CH 2CH3

Cl NO2

NH SO H 2 O2N 3 NO2 Cl CN COCl Cl Cl CH(CH3)2

O2N NO2 NO2 CONH2 COCH 3 OC H CO OH COOC H C2H5 2 CHO CONH2 2 5 Br Cl H2NOC

CHO I CN CH3 Cl

Answer: 3-methylaniline(m-toluidine), 1-chloro-2-nitrobenzene(o-nitrochlorobenzene), 3-sulfobenzoic acid, 1-chloro-4- ethylbenzene, 1,2-dinitrobenzene, 1,3-dichlorobenzene, 1-isopropyl -2-nitrobenzene, 4-acetylbenzonitrile, 3- (aminocarbonyl)benzoyl chloride, 1,3-dinitrobenzene, 1-bromo-3-iodobenzene, benzene-1,3-dicarbaldehyde, benzene-1,2-dicarboxamide, ethyl 4-cyanobenzoate, 1-ethyl-4-methylbenzene, 2,4-dichlorophenoxyacetic acid SAQ III.11: Write the preferred IUPAC names of the following compounds.

CN H3C CH3 CHO N NH2

CH3

CH3 (i) (ii) (iii) CH3

CH3

CHO

CH3 CHO CH3

COOH COOH (iv) (v) NO 2

Answer: (i) 3-[2-(dimethylamino)phenyl]butanal (ii)2-(2-methylprop-1-enyl)aniline (iii) 3-(1-oxopropan-2-yl)benzonitrile (iv)2-(2-formylphenyl)propanoic acid (v) 3-methyl-4-(2-nitrophenyl)but-2-enoic acid

Dr. S.S.Tripathy Nomenclature of Organic Compounds Tri or polysubstituted benzene: 1. If one of the groups belongs to type C, then the name is given after that groups getting locant 1. If more than one of such groups are there, then the highest priority groups determines the name of the compound. 2. If all the groups belong to type A, then LSL rule determines the name. See these examples.

OH Br NO2 1 5 2 Br 1 3 Br 6 2 6 4 5 3 1 3 O2N NO2 2 COOH 4 1,2,3-tribromobenzene 1,3,5-trinitrobenzene CH3 5-hydroxy-2-methylbenzoic acid

CHO CONH Br 2 2 NC 1 2 6 1 3 HO OH 5 1 NH2 6 4 4 2 6 5 3 5 COCH Br 3 Br 3 4 2,4,6-tribromoaniline 4-acetyl-2-formylbenzonitrile 2,6-dihydroxybenzamide

3 2 CH3 4 Cl H2NCl1 5

1 2 4 O N 2 O2N 3 4-chloro-2-methyl-1-nitrobenzene(correct) 5-chloro-2-nitroaniline(correct) 5-chloro-2-nitrotoluene(wrong) 2-amino-4-chloro-1-nitrobenzene(wrong)

CH3 2 3 NO2 CH2CH3 O2N 4 1 3 6 2-chloro-4-ethyl-1-methoxybenzene 4 2 5 (not 3-chloro-1-ethyl-4-methoxybenzen 1 Cl NO2 OC H3 2-methyl-1,3,5-trinitrobenzene(PIN (2,4,6-trinitrotoluene)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

SAQ:

COOCH3 COCH3 CH3 C2H5 COOCH3 CH3

COOCH3 O2N NO2 O2N CHO

OC H NO2 COCl 2 5 O N Br I 2 NO2 H3C NH2

NO2 Cl H3C COOH Cl Cl CH3

Answer: methyl 2-methyl-5-nitrobenzoate, 3-acetyl-5-nitrobenzaldehyde, 4-ethyl-2-methyl-1-nitrobenzene, dimethyl phthalate, 1-bromo-3-chloro-5-iodobenzene, 2-chloro-4-ethoxy-1-methylbenzene, 3,4-dimethyl-2-nitroaniline, 1,2,4- trinitrobenzene, 2-chloro-5-chlorocarbonylbenzoic acid

DIAZINES/AZO and AZOXY Compounds:

HN=NH : diazene CH3 NNCH3 (dimethyldiazene)

1 2 NN NN 1 2

diphenyldiazene (1-naphthyl)(2-naphthyl)diazene (azobenzene) (1,2’-azonaphthalene)

1 Cl 2 3 2 2 3 NN 1 NN1 4 Cl

(2-naphthyl)phenyldiazene (3-chlorophenyl)(4-chlorophenyl)diazene (naphthalene-2-azobenzene) (3,4'-dichloroazobenzene)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

NH2 2 CH3 1 1 2 NN 3 4 1 4 NN SO3H Cl

1-[(4-chloro-2-methylphenyl)diazenyl]naphthalen-2-amine 4-(phenyldiazenyl)benzenesulfonic acid

1 O SO3H

NN 3 N3

diphenyldiazene oxide 3-azidonaphthalene-2-sulfonic acid

(azoxybenzene) (N3– = azido group) Diazoninum compounds: Compound containing R-N2+ X– are called alkanediazonium halide (not alkyldiazonium halide)

CH2 CH2 (covalent structure) H3C NNCl H3C NNCl

ethyanediazonium chloride

- NNCl NNCl (covalent structure)

benzenediazonium chloride

1 + - HO 7 N2 BF4 NNOH

4

7-hydroxynaphthalene-2-diazonium tetrafluoroborate phenydiazenol (benzenediazonium hydroxide)

CH2NH2: (diazomethane)

Dr. S.S.Tripathy Nomenclature of Organic Compounds

POLYNUCLEAR AROMATIC COMPOUNDS Compounds containing more than one benzene ring fused at the ortho or 1,2 positons are called polynuclear or condensed aromatic compounds. A few examples are given below.

8 1 5 4 7 2 6 3 or 3 6 7 2 5 4 8 1 (napthalene) 10 4 8 9 1 5 7 2 6 3 or 2 6 3 7 9 5 10 4 8 1 (anthracene)

Then tetracenene(four benzene rings fused linearly), pentacene and so on. Monosubstituted naphthalene: For monosubstituted naphthalene, there are two non-equivalent positions namely 1-(α) or 2-(β).

1 1 2 2

2 2 1 1 Di- or polysubstituted naphthalene: For such compounds the numbering of carbon atoms is shown before. The highest priority functional group to get the lower locant.

CHO OH

COOH H3C

naphthalen-2-ol naphthalene-1-carboxylic acid 6-methylnaphthalene-1-carbaldehyde (β-naphthol)

4 5 5 4 CH3 OH H5C2 6 6 1 CN 2 1 1 COOH NH2

1-methylnaphthalene-2-carbonnitrile 6-hydroxynaphthalene-1-carboxylic acid 6-ethylnaphthalen-1-amine

Anthracene: For monosubstitued anthracene has 3 non-equivalent position, 1, 2 and 9. But for di- and polysubstituted anthracene, the numbering has been given before.

Dr. S.S.Tripathy Nomenclature of Organic Compounds

1 9 1 OH 2 2 COOH

2 2 1 9 1 anthrancene-2-carboxylic acid anthracen-9-ol

1 OH 2 CHO 1 9 2 7 NO2

5 4 6 4 CH 5 3 CH3

5-methylanthracene-2-carbaldehyde 4-methyl-2-nitroanthracen-9-ol Heteroaromatics and Heterocyclics:

4 4 4 3 4 3 3 5 3

5 5 2 5 2 2 6 2 N O S 1 H 1 N 1 1 furan pyrrole thiophene pyridine 4 4 5 3 5 3

2 6 2 6 1 N O H O O 1 4 4 3 4 3 4 3 5 3

5 1 2 5 1 2 5 1 2 6 1 2 NH O S N pyrrole funran thiophene pyridine N COOH

CHO N NH O pyrrole-2-carbaldehyde furan-3-carboxylic acid

OH

CH3

N 3-methylpyridin-4-ol

Dr. S.S.Tripathy Nomenclature of Organic Compounds

Other Heterocyclic Compounds: O

NH O O O tetrahydrofuran(THF) oxane 1,3-dioxane

NH NH NH HN NH

NH NH NH NH O 1,4-dihydropyrazine 1,3- 1,3,5- 4-H-pyran (1,4-diazinane)

Bicyclic Compounds: A bicyclic compound is one which can be converted to an open chain acyclic compound by making cleavage(scission or breakage) of covalent bonds two times.

1st cleavage 2nd cleavage

open chain

bridgehead carbon

bridges

bridgehead carbon There are two bridge head carbon atoms and three bridges. The bridge may contain only a single covalent bond(no carbon atom). bicylo[x.y.z]alkane x, y and z are ring size i.e number of carbon atoms in three bridges from highest to lowest bridges. This excludes the two bridgehead carbon atoms. If a bridge has no carbon atom(only a covalent bond) then it will get the numeral ‘0’. alkane will be from (x+y+z) +2 i.e all the carbon atoms. The numbering will start from one bridgehead through the longest bridge to the other bridgehead, then to bridge of intermediate length and shortest bridge. For naming a branched bicyclic compound, the priority order of functional group and LSL to be taken into account.

10

9 2

3 1

8 bicyclo[4.3.1]decane 4 6 7 5 Dr. S.S.Tripathy Nomenclature of Organic Compounds

3 2 2 1 1 0 1 0 5 bicyclo[2.2.0]hexane bicyclo[5.3.1]undecane bicyclo[1.1.0]butane

H3C 21 10 H3C 3 11 543

4 9 7

56 8 612 5-methylbicyclo[2.2.0]hex-2-ene 3-methylbicyclo[5.3.1]undec-8-ene

CH 3 OC H 3

6 4 5 5 7 8 3 6 10 HO 4 9 2 7 9

O 2N 1 3 1 8 2 6-methylbicyclo[5.2.1]dec-3-ene 4- methoxy-2-nitrobicyclo[3.2.2]nonan-6-ol SAQ: SAQ III.14:Write the names of the following bicyclics.

CH3

H3C

(i) (ii) (iii) CH3 (iv) (v) (vi)

H 2 N OHC

(vii) (viii) COOH (ix) (x)

H2N H2N Answer: (i) bicyclo[1.1.1]pentane (ii)bicyclo[2.2.2]oct-2-ene (iii)7-methylbicyclo[4.2.1]non-3-ene (iv)9- ethylbicyclo[3.3.2]decane (v)bicyclo[4.4.2]dodec-11-ene (vi) 8-methylbicyclo[5.2.0]non-2-ene (vii)bicyclo[5.3.1]undec-4-en-2-amine (viii)5-aminobicyclo[4.2.1]non-2-ene-7-carboxylic acid (ix)bicyclo[3.2.2]non- 2-en-6-amine (x)bicyclo[3.1.1]hept-2-ene-6-carbaldehyde

Dr. S.S.Tripathy Nomenclature of Organic Compounds

SPIRO COMPOUNDS: The compounds in which two rings share one common carbon atom are called spirocompounds. spiro[x.y]alkane x and y are chain lengths in the two rings or the number of carbon atoms in the two rings which link to the common atom(called spiro atom), which are separted by full stop. Note that the spiro atom is excluded in these numbers. The numbers are written in increasing order eg. [4.5] unlike that followed in bicyclic compounds(decreasing order). While naming the parent alkane the total number of carbon atoms in the compound is counted.

1 67

2

5 8

3

4 10 9 spiro[4.5]decane

The numbering starts in the smaller size ring from the carbon atom adjacent to the spiro atom and proceeds around the smaller ring back to spiro atom and then proceeds around the second ring(larger size ring). While going from the smaller ring towards the larger ring the lowest set of locants rule is kept in mind. If there is a C=C, then ene should get the lower locant compared to alkyl or other type A groups.

6 4 6 5 3 7 3 7 45 4 2 5 1 8 1 3 6 10 9 8 2

2 9 1 87 H 3 C spiro[4.4]nona-2,7-diene 1-ethylspiro[3.6]dec-6-ene H3C 8-methylspiro[2.5]oct-4-ene

SAQ III.15: Name the following spiro compounds.

H3C

(i) (ii)- CH3 (iii)

H3C

H3C

CH3

Dr. S.S.Tripathy Nomenclature of Organic Compounds

(iv) Cl (v)

H 3 C

Answer: (i) 1,4-dimethylspiro[2.7]deca-5,8-diene (ii) 6-isopropylspiro[3.5]non-1-ene (iii) 4-methylspiro[2.2]pent-1-ene (iv)1-chloro-5-ethylspiro[3.3]heptane (v) 4-methylspiro[4.8]trideca-1,7,9-triene

SUBSTITUTED OXIRANES(EPOXYALKANES), , LACTONES, LACTAMS, , KETENES

1. Substituted oxirane: The O atom of oxirane is always numbered 1. Alphabetical seniority of alkyl groups decides the correct direction of numbering. These are also named as epoxyalkanes, the locants of the epoxy are to be prefixed to it. 1 O 3 2 H 3 CCHCHCH2 CH 3 2-ethyl-3-methyloxirane (2,3-epoxypentane) 2. Imines: =NH is called group. It is a bivalent group. The name of imine is alkan-x-imine where x is the locant of imine. H C 3 CH 3 H 3 CCH2 CH 2 CH NH butan-1-imine NH propan-2-imine 3. Lactones: Cyclic are called lactones. Butyrolactone, valerolactone, caprolactone are a few examples of lactones.

CH 2 CH H 2 CH 2 2 C H C CH 2 H C H C 2 2 2 O CH 2 O H C H 2C H C 2 C C 2 O C O O O -butyrolactone -valerolactone -caprolactone 4. Lactams: Cyclic are called lactams. Butyrolactam, valerolactam, caprolactam are few examples of lactams. CH H 2 CH 2 CH 2 2 C H C CH 2 H C H C 2 2 2 NH CH 2 NH H C H 2C H C 2 C C 2 NH C O O O -butyrolactam -valerolactam -caprolactam

Dr. S.S.Tripathy Nomenclature of Organic Compounds

5. Ketenes: R-CH=C=O are called ketenes. Such compounds are named according to IUPAC rule.

Example: CH3-CH=C=O prop-1-en-1-one 6. Imides: Imides contain -CO-NH-CO- group. It is analogous to acid anhydride except -O-in anhydride is replaced by -NH- in . They are named according to IUPAC rules.

CH3-CO-NH-CO-CH3 N-acetylacetamide. ALTERNATIVE NAMING PROCEDURE FOR AND 20 AMINES Ethers:(OXA System) 1. Oxygen atom in is treated like a carbon atom in finding out the longest continuous chain including the oxygen atom. In otherwords, the oxygen atom is counted like a carbon atom in determining the the name of parent alkane. The ether group(oxygen atom) is indicated by the prefix oxa with its locant placed before it. Lowest set of locants rule is followed while choosing the direction of numbering. Note that ether group (O atom) does not enjoy any priority as functional group.

5 3 CH3 1

H3C O 2 6 4 (2-methyl-4-oxahexane)

CH3 Note that IUPAC does not have a fixed procedure for naming ethers, although the one discussed before(alkoxyalkane) is the preferred name. The oxaalkane procedure of naming ether is simpler, although used to a lesser degree of preference.

Cyclic ethers: When oxygen atom remains as a part of a ring, it is a cyclic ether. The systematic names of these ethers and their alternative names according to oxa system are given below.

O O O O

O oxirane oxetane oxacyclopentane 1,4-dioxacyclohexane (oxacyclopropane) (oxacyclobutane) (tetrahydrofuran or THF) (1,4-dioxane)

Note that oxirane is also commonly called ethylene oxide or epoxyethane. Sec-amines (AZA System) Like oxygen atom in ether, the nitrogen atom in a sec-amino group( NH) is counted like a carbon atom in finding out the longest continuous chain. The prefix aza is used for the amino function with its locant before it.

4 2 OH

1 H3C NH 5 3 3-azapentanoic acid [ 2-(ethylamino)acetic acid/N-ethylglycine] O

Dr. S.S.Tripathy Nomenclature of Organic Compounds Trivial System(Common Names): Type of Carbon atoms: (a) Primary (10) (b) secondary (20) (c) tertiary(30) (d) quaternary(40)

CH3 CH3 10 0 30 2 40 CH3 CH CH2 C CH3

CH3

Types of Alkyl Groups: (a) n-alkyl : straight chain : example n-propyl, n-butyl, n-pentyl etc. ( n = normal)

CH3 CH2 CH2 CH3 CH2 CH2 CH2

n-propyl n-butyl (b) sec-alkyl: derived from a 20 carbon atom. The carbon bearing the unsatistfied valency has one H atom.

CH3 CH2 CH CH3 CH3 CH2 CH CH2 CH3

sec-butyl sec-pentyl

CH3 CH2 CH2 CH CH3

sec-pentyl There is only one sec-butyl and hence can be used in naming. But there are two sec-pentyl groups, hence cannot be used for naming. Can you say how many sec-hexyl group you can have from hexane ? Again two. You will get clear picture about this in the chapter ‘Isomerism’. (c) tert-alkyl: derived from a 30 carbon atom. The carbon bearing the unsatisfied valency has NO H atom in it.

CH3 CH3

CH3 C CH3 C

CH3 CH2CH3

tert-butyl tert-pentyl Since there is one from each of the above, they can be used in naming.

Dr. S.S.Tripathy Nomenclature of Organic Compounds

(d) isoalkyl group: contain -CH3 branch at the 2nd position.

CH3 CH3 CH3

CH3 CH CH3 CH CH2 CH3 CH CH2 CH2

isopropyl(sec-propyl) isobutyl isopentyl Note that isopropy is also sec-propyl as it satisfies both the definitions. But isopropyl is preferred. (d) neopentyl group:

CH3

CH C CH 3 2 (neopentyl) CH3

Naming by Common System(traditional or trivial system):

CH3 CH2 CH2 CH3 CH3 CH2 CH2 CH2 CH3

n-butane n-pentane

CH3 CH3 CH3 CH3 C CH3 CH3 CH CH3 CH3 CH CH2 CH3 CH3

isobutane isopentane neopentane

CH3 O CH CH 3 3 CH C CH OH 3 2 CH3 C CH CH3 CH2 CH Cl CH CH3 3

sec-butyl chloride neopentyl alcohol isopropyl methyl ketone

CH3 CH CH OCCH 3 2 3 tert-butyl ethyl ether CH3

Dr. S.S.Tripathy Nomenclature of Organic Compounds

BRACKET SYSTEM OF STRUCTURE WRITING:

CH CH3 OH 3 CH CH C COOH (CH3)2CHCH(OH)C(CH3)2COOH = CH3 CH3

CH3 O CH3

CH3 C C CH CH2 CH2 CH2 CH3 (CH3)3CCOCH(CH3)(CH2)3CH3 = CH3

Short Notations: n-Bu (n-butyl); i-Pr (isopropyl); t-Bu (tert-butyl); n-Pr ( n-propyl); Me(methl): Et(ethyl)

Dr. S.S.Tripathy