Question

Arrange the following compounds in increasing order of their property as indicated: (i) Acetaldehyde, Acetone, Di-tert-butyl ketone, Methyl tert-butyl ketone (reactivity towards HCN) (ii) CH3CH2CH(Br)COOH, CH3CH(Br)CH2COOH, (CH3)2CHCOOH, CH3CH2CH2COOH (acid strength) (iii) Benzoic acid, 4-Nitrobenzoic acid, 3,4-Dinitrobenzoic acid, 4-Methoxybenzoic acid (acid strength)

Answer 1

Answer:

(i) We know that the the reactivity of a compound is depended on the steric hindrance which is due to groups which are present around the carbonyl group.And if the steric hindrance is greater, reactivity of the compound will be less.Hence, the reactivity towards HCN is :-

Di-tertiary butyl ketone < Methyl tertiary butyl 1-retorie < Acetone< Acetaldehyde.

(ii) It is known that the alkyl group having +I effect decreases the acidic strength while the -I effect increases the acidic strength Increasing order of acidic strength is    Increasing order of acidic strength is    

(CH3)2CHCOOH<CH3CH2CH2COOH <CH3CH2CH(Br)COOH< CH3CH(Br)CH2COOH.

(iii)Since, the electron donating group causes decrease in the acidic strength while we know that electron withdrawing group always increases the acidic strength.Thus, increasing order of acidic strength will be:

4-methoxy benzoic acid < benzoic acid < 4-nitrobenzoic acid<3,4-dinitrobenzoic acid.