221.
Benzaldehyde can be prepared from benzene by passing vapours of _______ and _______ in its solution in presence of catalyst mixture of aluminium chloride and cuprous chloride. The reaction is known as _______ .
TIPS/Formulae :
Ketone (non-reducing) and aldehyde (reducing) can be distinguished by Fehling solution.
223.
An organic compound $$(X)$$ with molecular formula $${C_9}{H_{10}}O$$ gives positive 2, 4-$$DNP$$ and Tollens' tests. It undergoes Cannizzaro reaction and on vigorous oxidation it gives 1, 4-benzenedicarboxylic acid. Compound $$(X)$$ is
NOTE : $$ - CHO$$ produces $$ - R$$ effect i.e. it withdraws electrons from the double bond or from a conjugated system towards itself.
227.
Reaction of a carbonyl compound with one of the following reagents involves
nucleophilic addition followed by the elimination of water. The reagents is
A
a Grignard reagent
B
hydrazine in presence of feebly acidic solution
C
hydrocyanic acid
D
sodium hydrogen sulphite
Answer :
hydrazine in presence of feebly acidic solution
Reaction of carbonyl compounds with one of the following reagents involves nucleophilic addition followed by elimination of water.
The reagent is hydrazine in presence of feebly acidic solution.
For example, the reaction between acetone and hydrazine to form hydrazone is shown below.
228.
Which of the following reagents are not correctly matched with the reaction?
A
$$C{H_3}CH = CHCHO \to C{H_3}CH$$ $$ = CHCOOH:{\text{Ammoniacal}}\,\,AgN{O_3}$$
B
$$C{H_3}CH = CHCHO \to C{H_3}CH$$ $$ = CHC{H_2}OH:{H_2}/Pt$$
C
$$R - COOH \to R - C{H_2}OH:NaB{H_4}$$
D
$$C{H_3}C{H_2}COCl \to C{H_3}C{H_2}CHO$$ $$:{H_2},Pd/BaS{O_4}$$