Question

write the preparation of primary, secondary and tertiary alcohol from grignard reagent

Answer 1

Answer:

For 1°-OH:

Formaldehyde (methanal) on treatment with grignard reagent followed by acid hydrolysis yield primary alcohol.

e.g, H

|

H-CHO + CH3MgCl __CH3-C-OMgCl

Methanal G.R. |

H

+

CH3CH2OH_____H2SO4/H2O

primary alcohol acid in water

( Ethanol)

For 2°- OH:

Aldehydes except methanal on treatment with grignard reagent followed by acid hydrolysis yield

2°-OH.

e.g,

(CH3)2CHO + CH3MgCl. +

Aldehyde G.R. H2SO4/

(CH3)2CHOH ______H20

2°-OH

FOR 3°-OH:

Ketones on treatment with grignard reagent followed by acid hydrolysis yield 3°-OH.

e.g,

CH3COCH3 + CH3MgBr +

Acetone G.R. H2SO4/

(CH3)3COH______H2O

3°-OH

Note:

Formaldehyde yield 1°-OH,

Other aldehyde yield 2°-OH and

Ketones always yield 3°-OH with

Grignard reagent(G.R.).

Explanation: