Question

Which of the following alcohols can be oxidised by ${K_2}C{r_2}{O_7}$
(A) Ethanol
(B) Tert Butyl Alcohol
(C) Isopropyl alcohol
(D) Allyl alcohol

Answer 1

Hint: Potassium dichromate is a strong oxidising agent which oxidises almost all types of functional groups including alcohol. We will check according to the structure of alcohol which will be oxidised or not.

Complete Solution :
-Potassium dichromate is a strong oxidising agent which oxidises all the functional groups including alcohol.
- we have ethanol given it converts into ethanoic acid
- reaction is as follows
- $C{H_3}C{H_2}OH \to C{H_3}COOH$ in presence of potassium permanganate
-we have tertiary butyl alcohol , the reaction is as follows
-${(C{H_3})_3}C - OH \to \times $ it does not give reaction as tertiary butyl alcohol can’t be oxidised
 so this option is incorrect
-next we have isopropyl alcohol it also gets oxidised in presence of potassium dichromate
-the reaction is as follows
  $C{H_3} - CHOH - C{H_3} \to C{H_3}COC{H_3}$ here it oxidises into acetone.
-Further we have allyl alcohol which converts into acid
The reaction is as follows
-$C{H_2} = CH - C{H_2} - OH \to C{H_2} = CH - C{H_2} - COOH$

-It gets converted to acid in presence of potassium dichromate
So, the correct answer is “Option A,C and D”.

Note: Acidified potassium dichromate is used to change to green when alcohol is oxidised and is used as a test for alcohols .