question_answer

The best hydride donor intermediate in Cannizaro reaction will be

A)                                     

B)

C)                                           

D)

Correct Answer: D

Solution :

 Idea This problem includes conceptual mixing of Cannizaro reaction and effect of inductive effect on Cannizaro reaction. While solving this problem, the students are advised to see stability of dianion obtained as intermediate. Cannizaro reaction Conversion of 2 molecules of aldehyde to acid and alcohol due to self oxidation as well as reduction in which one molecule is oxidised to carboxylic acid and one molecule is reduced to alcohol.                             Necessary condition of Cannizaro reaction is that substrate should not contain \[\text{ }\!\!\alpha\!\!\text{ -}\]hydrogen atom and base is used to conduct the reaction.           \[HCHO\xrightarrow[{}]{O{{H}^{\Theta }}}HCHOH+HCOOH\] Role of inductive effect The group having-I effect increases the possibility of hydride transfer hence faster the hydride transfer. \[N{{O}_{2}}\]is an electron pulling group causes -/ effect to ring and increases the \[{{H}^{\Theta }}\] transfer ability so \[{{H}^{\Theta }}\]transfer occur faster here. TEST Edge Problems related to generation of carbanions such as Mannich reaction, Perkin reaction, benzoin condensation all are also asked in JEE Main frequently. So, students are advised to go through these topics.