Amide Structure :O: 1179 、,H ←> H N H 121° 119 H H formamide Copyright2010 Pearson Prentice Hall.Inc Amides are the product of the reaction of a carboxylic acid with ammonia or an amine. Not basic because the lone pair on nitrogen is delocalized by resonance. The C-N bond has double-bond character. Chapter 21 6
Chapter 21 6 Amide Structure ▪ Amides are the product of the reaction of a carboxylic acid with ammonia or an amine. ▪ Not basic because the lone pair on nitrogen is delocalized by resonance. ▪ The C—N bond has double-bond character
Protonation of Amides H+ concentrated acid N一R very weakly basic protonation on oxygen Copyright 2010 Pearson Prentice Hall.Inc -Under acidic conditions,the double-bonded oxygen will get protonated. Chapter 21 7
Chapter 21 7 Protonation of Amides ▪ Under acidic conditions, the double-bonded oxygen will get protonated
Classes of Amides 0 CH3 H H-C-N CH3-C-N CHCH2-C-N CH: CH dimethylformamide N-methylacetamide propionamide 3°amide 2°amide 1°amide 1 amide has one C-N bond (two N-H). 2 amide or N-substituted amide has two C-N bonds (one N-H). 3 amide or N,N-disubstituted amide has three C-N bonds (no N-H). Chapter 21 8
Chapter 21 8 Classes of Amides ▪ 1 amide has one C—N bond (two N—H). ▪ 2 amide or N-substituted amide has two C—N bonds (one N—H). ▪ 3 amide or N,N-disubstituted amide has three C—N bonds (no N—H). 3º amide 2º amide 1º amide
Nomenclature of Amides CH3 N-ethyl-N-methyl-2-dimethylpropanamide CH3CHC-N-CH2CH3 (N-ethyl-N-methylisobutyramide) CH3 For 1 amide,drop -ic or -oic acid from the carboxylic acid name,add -amide. Alkyl groups bonded to nitrogen are named with N-alkyl to indicate their attachment to the nitrogen atom. Chapter 21 9
Chapter 21 9 Nomenclature of Amides ▪ For 1 amide, drop -ic or -oic acid from the carboxylic acid name, add -amide. ▪ Alkyl groups bonded to nitrogen are named with N-alkyl to indicate their attachment to the nitrogen atom. N-ethyl-N-methyl-2-dimethylpropanamide CH3CHC N (N-ethyl-N-methylisobutyramide) O CH2CH3 CH3 CH3
Cyclic Amides H.N-CH,CH,-CH,-c-OH H heat H,0 HH IUPAC name: 4-aminobutanoie acid 4-aminobutanoic acid lactam common name: y-aminobutyric acid y-butyrolactam CH CH IUPAC name: 3-aminopropanoic acid lactam 6-aminohexanoic acid lactam 4-amino-2-methylpentanoie acid lactam common name: B-propiolactam e-caprolactam a-methyl-y-valerolactam Copyright2010 Pearson Prentice Hall,Inc. Cyclic amides are called lactams. To name,add the word lactam to the lUPAC acid name or replace the -ic acid of common name with -olactam. Chapter 21 10
Chapter 21 10 Cyclic Amides ▪ Cyclic amides are called lactams. ▪ To name, add the word lactam to the IUPAC acid name or replace the -ic acid of common name with -olactam