Answer to Question #165366 in Organic Chemistry for ulmighty super

Question

Carboxylic acids can be converted into acid derivatives R.CO₂H ➡ RCOX, where X may be an organic or inorganic group.

(i) Arrange the four derivatives in order of increasing rate of hydrolysis (putting the slowest first). Explain your answer.

(ii) Show how any one of the derivatives can be converted into another.

Answer 1

Hydrolysis reaction of carboxylic acid derivatives is example of nucleophilic substitution reaction

The four derivatives of carboxylic acid are

RCONH₂ (amides),RCOOR(esters), (RCOO)₂O (anhydrides) and RCOX( acyl halide)

The increasing order of reactivity toward hydrolysis of carboxylic acid derivatives

RCONH₂ < RCCOR < (RCOO)₂O < RCOX

There are two major factors affect the rate of hydrolysis reaction are following

1. the stability of the carbonyl compound,

and 2. the leaving-group ability of anion

and we know that halogen are more electronegative they have more tendency to loose electron where as lone pair on NH2 group make it less leaving group .

2.

We can take example of conversion of esters to amides

$CH_3COOC_2H_5 + NH_3 \xrightarrow{ \Delta} CH_3CONH_2 + C_2H_5OH$