Question

(a) Illustrate the following name reactions by giving example :

(i) Cannizzaro’s reaction

(ii) Clemmensen reduction

(b) An organic compound A contains 69.77% carbon, 11.63% hydrogen and rest oxygen. 

The molecular mass of the compound is 86. It does not reduce Tollens’ reagent but form an addition compound with sodium hydrogen sulphite and gives positive iodoform test. On vigorous oxidation it gives enthanoic and propanoic acids. Derive the possible structure of compound A.

Answer 1

(a) (i) Cannizzaro’s reaction :- Aldehydes which do not contain α-H atom undergo disproportionation when heated with concentrated (50%) NaOH.

(ii) Clemmensen reduction :- The carbonyl group of aldehydes and ketones is reduced to CH₂ group on treatment with zinc amalgam and concentrated hydrochloric acid.

(b) Calculation of the empirical formula of the compound :

So, the empirical formula is C₅H₁₀O

Empirical formula mass

= (5 × 12) + (10 × 1) + (1 × 16) = 86

Given that molecular mass of the compound = 86

Hence, the molecular formula of the compound is

C₅H₁₀O.

The given compound does not reduce Tollens’ reagent, so it is not an aldehyde but the formation of addition compound with sodium hydrogen sulphite indicates it to be a carbonyl compound. Since this compound gives positive iodoform test, so it should contain  group.

On the basis of this information, two possible structures are written as under :

On oxidation, this compound gives ethanoic and propanoic acids which confirm its structure to be I.