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Nomenclature –Naming of Organic Compounds

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‘Trivial’ Names…

Aspirin

Cubane Housane Basketane Olympicene

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IUPAC International Union of Pure and Applied Chemistry

Pentacyclo[4.2.0.02,5.03,8.04,7]octane

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Naming Organic Compounds

Chains

meth 1 C eth 2 C C prop 3 C C C but 4 CCCC pent 5 C C C C C hex 6 C C C C C C hept 7 C C C C C C C oct 8 C C C C C C C C non 9 C C C C C C C C C

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Chains – Numbering Positions of Substituents

Cl C C C C C C C 2‐chloro… 1234567

Cl C C C C C C C 3‐chloro…

7 6 5 4 3 2 1

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Single and Multiple Carbon‐Carbon Bonds in Chains

C C C C C C Single carbon‐ Contains a Contains a an carbon bonds en carbon‐carbon yn carbon‐carbon only double bond triple bond

C C C C C C C …‐1‐ene 1234567

C C C C C C C …‐2‐ene 1 234567

C C C C C C C …‐3‐ene 7 6 5 4 3 2 1

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Branches to Carbon Chains

H

H C CH3 methyl H Common H H branches H C C CH CH ethyl on chains: 3 2 H H H H H

H C C C CH3 CH2CH2 propyl H H H

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Position (3‐) Branch (methyl) Longest chain HHCH HHHH Length of longest chain (7 = hept) 3 Only single C‐C bonds (ane) H C C C C C C C H 1234567 3‐methylheptane HHHHHHH

HHHHH H C C C C C H 3 4 5 6 HHHH 3‐methylhexane H C 2 H Longest chain

H C1 H H

2‐methylhex‐2‐ene

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For each of the alkanes below, identify and highlight the longest unbroken chain.

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Name the following alkanes.

2,4‐dimethylpentane 3‐methylpentane 2‐methylpentane 3‐ethylhexane

4,5‐diethylnonane 2,3,4,6‐tetramethylheptane

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Draw the skeletal structures of the following alkenes.

(i) but‐2‐ene

(ii) 2‐methylbut‐2‐ene

(iii) 2,3‐dimethylbut‐2‐ene

(iv) 3‐ethyl‐2‐methylpent‐1‐ene

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Functional Groups Haloalkanes (R‐F, R‐Cl, R‐Br, R‐I)

Cl Cl

2‐chloropentane Cl 2,3‐dichloropentane

When different halides are on a chain, the numbering is done to get the lowest possible numbers for the positions and then it is named so that the substituents are in alphabetical order.

Cl

5 –bromo‐2‐chloroheptane

Br

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Alcohols (R‐OH)

OH OH OH

OH propan‐2‐ol pentan‐2,3‐diol 2‐methylpentan ‐3‐ol Aldehydes (R‐CHO) have names ending in –al. The carbon atom of the aldehyde group counts as a member of the chain. The carbon of the aldehyde is always counted as number 1. Numbers are only used if there are substituents or branches on the main chain.

O O

H H propanal 2‐methylpentanal

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Ketones (RCOR’) have names ending in –one.

O

pentan‐2‐one

Carboxylic Acids (RCOOH) have names ending in –oic acid. The carbon in the acid group is part of the chain and is always counted as 1 when numbering.

O OH O

OH OH

propanoic acid 3‐hydroxybutanoic acid

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Esters (RCOOR’) are derivatives of acids where the H is replaced by an alkyl group. The naming of acid is therefore a combination of the alkyl group followed by a name derived from the acid (‐oate)

O

OH HO O butanoic acid ethanol

O ethyl butanoate

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Acyl Chlorides (RCOCl) are derivatives of acids where the H is replaced by a chlorine.

O

Cl pentanoyl chloride

O

Cl 3‐methylbutanoyl chloride

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Primary Amines (RNH ) have the amine group (‐NH ) attached to a 2 2 carbon chain. If the chain is short (n=1 or 2) there is no ambiguity about where the group is so –amine is attached to the alkyl group name. For longer groups amino‐ is used along with a number.

NH2

NH2 ethylamine 2‐aminopentane

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Secondary and Tertriary Amines (RR’NH, RR’R’’N) have two or three alkyl groups attached to a nitrogen atom. There name reflects the alkyl groups and how many of them there are.

NH N

diethylamine trimethylamine

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Ethers (ROR’) These are related to alcohols, but the H atom has been replaced by an alkyl group. One way to name them is to use the term ‘alkoxy‐’ (e.g. methoxy‐) as a substituent.

1‐methoxypropane 1‐ethoxy‐2‐methylpropane

Simpler ethers may be named by listing the name of each of the names of the groups (alphabetical order) attached to the oxygen atom followed by ‘ether’.

methyl propyl ether ethyl 2‐methylpropyl ether

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Amides (RCONH ) is carboxylic acid derivative where the –OH of the acid 2 group is replaced by a –NH2 group. There names end with –amide.

O

NH2 propanamide

Nitriles (RCN) are compounds that contain a carbon atom with a triple bond with nitrogen. Their names ends with –nitrile. The carbon counts as part of the chain when numbering.

N propanenitrile

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propylamine ethylbutanoate 3‐methylbutanenitrile

butan‐2‐one 2,4‐dimethylpentanal 2‐bromo‐1,3‐dichloropentane

pent‐2‐en‐4‐one butan‐2‐ol 3‐methylbutanamide

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Cyclic Compounds

cyclopentane cyclohexane cyclooctane

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Cyclic Compounds ‐ Numbering Cl 1 6 2 5 3 4 chlorocyclohexane cyclohexene

Cl Cl Cl

Cl 1,2‐dichlorocyclohexane 1,3‐dichlorocyclohexane cyclohexa‐1,4‐diene

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If a small, simple chain is attached to the ring then the alkyl group is considered as the substituent.

ethyl cyclohexane

If the attached chain is large, or complex then the ring may be named a substituent.

H O

5‐cyclohexylpentanal

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