An organic compound (A) of molecular formula C_2H_4O_2gives brisk effervescence with sodium carbonate. (A) on reaction with thiony chloride gives (B) of formula C_2H_3OCl . (B) on reaction with Pd//BaSO_4gives (C) of molecular formula C_2H_4Othat reduces Tollen's reagent to silver mirror. (C) on reaction with dilute NaOH gives (D) of molecular formula C_4H_8O_2. . Identify A,B,C,D and explain the reactions involved.

An organic compound (A) of molecular formula C_2H_4O_2gives brisk effe

1.	An organic compound (A) of molecular formula C_2H_4O_2gives brisk effervescence with sodium carbonate. (A) on reaction with thiony chloride gives (B) of formula C_2H_3OCl . (B) on reaction with Pd//BaSO_4gives (C) of molecular formula C_2H_4Othat reduces Tollen's reagent to silver mirror. (C) on reaction with dilute NaOH gives (D) of molecular formula C_4H_8O_2. . Identify A,B,C,D and explain the reactions involved.
Answer» Solution : (i) (A) gives brisk effervescence with `Na_2CO_3`means it must be a carboxylic ACID. So (A) must be `CH_3COOH` Acetic acid. (ii) Acetic acid reacts with thionyl chloride to give acetyl chloride `CH_3COCl` as (B) . ` underset("acetic acid (A) ")(CH_3COOH) + SOCl_2 to underset("acetyl chloride (B)")(CH_3COCl) + SO_2 uarr + HCl` (III) Acetyl chloride reacts with `Pd//BaSO_4` , it undergoes Rosenmund.s reduction to give acetaldehyde as (C) `CH_3COCl underset([H])overset(Pd//BaSO_4)(to) underset("acetaldehyde (C )")(CH_3CHO) + HCl` (iv) When acetaldehyde is warmed with dilute NaOH, it undergoes aldol condensation to `CH_3 - oversetunderset(\|)(H)( C) = O + H - CH_2 CHO overset(dil.NaOH)(to) underset("acetaldolor 3 - hydroxy butanal")(CH_3- undersetoverset(\|)(OH)(C ) H - CH_2CHO)`