AMIDES & AMINES

Introduction So far, we’ve dealt with compounds containing C, H, and O atoms. Many naturally produced compounds also contain nitrogen. Organic compounds that contain nitrogen can either be called amines or amides

AMINES Can be thought of as ammonia (NH 3 ), with one, two or all three of its hydrogens substituted by alkyl groups The number of substituted alkyl groups allow for primary (1 0 ), secondary (2 0 ), and tertiary (3 0 ) sub-classifications (similar to alcohols)

Common Names for Amines: Text method 1.Identify the largest alkyl group attached to the nitrogen atom as the parent alkane 2.Replace the -e at the end of the parent alkane with the new ending –amine. Include a position number if required Butan-1-amine

IUPAC Names for 2 0 and 3 0 Amines The IUPAC names for 2 0 and 3 0 amines include the N- prefix to denote the substituted groups on the N atom of the amino group. The larger alkyl group determines the main chain If the structure is a 3 0 amine, one group must be considered the main chain, while the other groups are considered branches Additional side chains are listed in alphabetical order as normal

N-methylbutan-1-amine N,N-dimethylmethanamine 5-chloro-N,N-dimethylhexan-3-amine

Properties of Amines N-C and N-H bonds are polar, thereby allowing for dipole-dipole and London forces. In addition, N-H bonds allow for hydrogen bonding. Note that N-H hydrogen bonds are weaker than O-H hydrogen bonds

Preparing Amines: Substitution Reactions Amines are prepared by the reaction of ammonia with an alkyl halide (let X represent any halogen)

AMIDES

Structure and Properties Contain the amide linkage as their functional group. Structurally similar to esters. Amide linkage is very significant in biological systems as the forming and breaking of these bonds give specificity to proteins.

Naming Amides Locate the part of the amide that contains the C=O group. Name the parent carboxylic acid that this part derives from. The C=O group is always given position number 1 ethanamide Replace the –oic acid ending of the name of the parent acid with the suffic –amide Ethanoic acid 1 2

If the amide is a 2 0 amide, name the alkyl group and give it location letter N- to indicate that it is bonded to the nitrogen atom Amide Branches If the amide is a 3 0 amide, place the alkyl groups in alphabetical order. Use location letter N- before each group to indicate that it is bonded to the nitrogen. If the two groups are identical, use N,N-

N,N-diethylethanamide N-ethyl-N,3-dimethyl H 3 CH 2 C C O N CH 3 H CCH 2 H 2 CCH 3 O N CH 3 H 2 C H 3 C Examples Parent carboxylic chain N-methyl Alkyl group N-ethyl-N-methyl propanamide butanamide

Preparation Amides are made through a condensation reaction of a carboxylic acid and a primary or secondary amine. Tertiary amines can not be used as they do not contain a hydrogen. carboxylic acid + 1 or 2 amine amide + water H 2 SO 4 ° ° methanamine

Amino Acids Amino acids are bifunctional because they contain both an amino group (NH 2 ) and a carboxyl group (COOH). Depending on what they are mixed with, amino acids can act as either an acid or a base. The amino and carboxyl groups are attached to the same carbon (  carbon). The 20 different amino acids only differ in their side chains (R group).