toreondemand.blogg.se - Carboxyl functional group

Hydrolysis of a protein is typically achieved by treating it with boiling 6M hydrochloric acid. Amino acids have both an amine functional group and a carboxylic acid functional group in the same molecule and proteins are formed by linking the amine group from one molecule with the carboxylic acid group of another to form an amide bond. They are polymeric materials formed from amino acids. It is a nucleophilic substitution reaction ( addition + elimination = substitution).The mechanism is the same for all the acid derivative interconversions and hydrolysis reactions.Hydrolysis under basic conditions results in formation of a carboxylate ion and hydrolysis of amides under acid conditions results in formation of an ammonium ion.The reaction is directly analogous to the interconversion of derivatives.The ease of hydrolysis depends on the stability of the derivative: acid chlorides hydrolyse in water at pH 7 esters require a H + or OH - catalyst and heat to hydrolyse amides require prolonged heating with more concentrated H + or OH.All derivatives hydrolyse with water to form the carboxylic acid.The polarity of the fragments can be used to decide what the final products are. In the outcome of all reactions of acid derivative the bond between the acyl group and the heteroatom breaks and, in the reagent, the bond between the hydrogen and heteroatom breaks.Acid chlorides are more reactive than esters which are more reactive than amides.A more reactive derivative may be converted into a less reactive one.Acid chlorides are formed by treatment of a carboxylic acid with thionyl chloride, SOCl 2.Three classes dealt with here: acid chlorides, esters and amides (in the lab another derivative, an acid anhydride, is used for convenience).Carboxylic acid derivatives all have an acyl group, attached to a heteroatom (O, N, halogen).Questions on Carboxylic Acid Nomenclature

Some biologically active compounds containing the

A carboxylic acid and an alcohol will form an ester and water.

Carboxylic acids react with dilute aqueous sodium hydroxide solution to form the water soluble carboxylate ion.

The carboxylate ion is a resonance stabilised carbanion.

Carboxylic acids are weak acids with p K a values ~ 4-5.

Carboxylic acids show a strong absorption around ~ 1700 cm -1 (C=O) and a very broad absorption around ~ 3000 cm -1 (O-H) in the infrared region.

Some simple carboxylic acids have non-systematic names.

The conjugate bases are named by replacing the – oic acid ending with – oate.

If substituents are present, start the numbering from the carboxyl group - C1.

The longest chain containing the COOH group gives the stem ending – oic acid.Reference: McMurry Ch 10 George et al Ch 2.7Ĭarboxylic acids contain the functional group: