Question

1. Give the mechanism for nucleophilic addition reactions to aldehydes and ketones, list factors that affect this reaction.

2. Give the mechanism for the Wittig reaction.

3. Discuss nucleophilic acyl substitution reactions and provide key examples to make your point.

4. List the major nomenclature rules for acid chlorides, anhydrides, carboxylic acids, esters, amides and nitriles.

Answer 1

Nomenclature

• Esters: The alkyl group is named first, followed by a derived name for the acyl group, the oic or ic suffix in the acid name is replaced by ate.
e.g. CH₃(CH₂)₂CO₂C₂H₅ is ethyl butanoate (or ethyl butyrate).
Cyclic esters are called lactones. A Greek letter identifies the location of the alkyl oxygen relative to the carboxyl carbonyl group.
• Acid Halides: The acyl group is named first, followed by the halogen name as a separate word.
e.g. CH₃CH₂COCl is propanoyl chloride (or propionyl chloride).
• Anhydrides: The name of the related acid(s) is used first, followed by the separate word "anhydride".
e.g. (CH₃(CH₂)₂CO)₂O is butanoic anhydride & CH₃COOCOCH₂CH₃ is ethanoic propanoic anhydride (or acetic propionic anhydride).
• Amides: The name of the related acid is used first and the oic acid or ic acid suffix is replaced by amide (only for 1º-amides).
e.g. CH₃CONH₂ is ethanamide (or acetamide).
2º & 3º-amides have alkyl substituents on the nitrogen atom. These are designated by "N-alkyl" term(s) at the beginning of the name.
e.g. CH₃(CH₂)₂CONHC₂H₅ is N-ethylbutanamide; & HCON(CH₃)₂ is N,N-dimethylmethanamide (or N,N-dimethylformamide).
Cyclic amides are called lactams. A Greek letter identifies the location of the nitrogen on the alkyl chain relative to the carboxyl carbonyl group.
• Nitriles: Simple acyclic nitriles are named by adding nitrile as a suffix to the name of the corresponding alkane (same number of carbon atoms).
Chain numbering begins with the nitrile carbon . Commonly, the oic acid or ic acid ending of the corresponding carboxylic acid is replaced by onitrile.
A nitrile substituent, e.g. on a ring, is named carbonitrile.
e.g. (CH₃)₂CHCH₂C≡N is 3-methylbutanenitrile (or isovaleronitrile).