Question

What of the following is not a good method to prepare 2,2-dimethylpropanoic acid? K2Cr2O7, H2SO (A) OH 1) Mg, diethyl ether Br 2) COZ 3) H30* 1) NaCN 2) H307, heat Cros, H2SO4

Answer 1

If we want to prepare 2,3-dimethyl propanoic acid all are good methods except option @. . Because In ② K2Cr2O7 / H₂ 504 is a good onidising agent and it oxidises the primary alcholic group to the acid Ky(7207 XOHH₂504 KroH In option also we can prepare 2, 3 dimethyl propaonic acid easily as the grignard reagent would attack co2 easily. I X Bro v Mg mg Bo ether X Mg Br O=CO X9-0 Mg Bro J 4300 X -OH ocn

In option ③ the reagent is The Jone's reagent, which is a very good oxidising reagent to convert alchol or aldehyde to acid by the formation of chromate ester. cron -COOH H₂SO4 But option ① is not favourable as it involves SN2 atták in the first step. To produce acid at first ca would attack 3 carbon centre backside and Bro leaves then the acid forms. But a SN2 attack at zo Carbon is not favourable. cxon Yo tau not favourable So, ② is not a good method. correct answer is option © . GO