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Nomenclature – Naming of Organic Compounds

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Nomenclature – Naming of Organic Compounds 12/05/2020 Nomenclature –Naming of Organic Compounds 1 ‘Trivial’ Names… Aspirin Cubane Housane Basketane Olympicene 2 1 12/05/2020 IUPAC International Union of Pure and Applied Chemistry Pentacyclo[4.2.0.02,5.03,8.04,7]octane 3 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 4 2 12/05/2020 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 5 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 6 3 12/05/2020 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 7 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 8 4 12/05/2020 For each of the alkanes below, identify and highlight the longest unbroken chain. 9 Name the following alkanes. 2,4‐dimethylpentane 3‐methylpentane 2‐methylpentane 3‐ethylhexane 4,5‐diethylnonane 2,3,4,6‐tetramethylheptane 10 5 12/05/2020 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 11 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 12 6 12/05/2020 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 13 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 14 7 12/05/2020 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 15 Acyl Chlorides (RCOCl) are derivatives of acids where the H is replaced by a chlorine. O Cl pentanoyl chloride O Cl 3‐methylbutanoyl chloride 16 8 12/05/2020 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 17 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 18 9 12/05/2020 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 19 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 20 10 12/05/2020 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 21 Cyclic Compounds cyclopentane cyclohexane cyclooctane 22 11 12/05/2020 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 23 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 24 12.
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