Question 1

There are three alcohols  x,\ y,\ z  which have  2,\ 1  and  0  alpha hydrogen atom(s) respectively. Which does not give Lucas test immediately?

Accepted Answer

Lucas reagent is  ZnCl_2  and  HCl .Primary alcohols do not react with Lucas reagent.Since ' x ' contains two alpha hydrogens, it must be a primary alcohol. R-CH_2-OH  is primary alcohol which have 2 alpha hydrogen.Option A is correct.

Question 2

Dehydration of the alcohols will be in order:

Accepted Answer

The dehydration of tertiary alcohol is faster than the dehydration of the secondary alcohol.Also, the dehydration of the secondary alcohol is faster than the dehydration of primary alcohol.Thus, the order of dehydration is  IV  (tertiary\  alcohol)  >II  (secondary\  alcohol)>  III  (secondary\  alcohol) >I  (primary\  alcohol) .The alcohol  II  is more easily dehydrated than the alcohol  III  as in the alcohol  II , the secondary carbocation has 5 alpha hydrogen atoms takes part in hyperconjugation while in  III  there are only 3 alpha hydrogens.

Question 3

Which of the following reagents should be used to prepare tert-butyl ethyl ether?

Accepted Answer

tert -butyl ethyl ether can be prepared by the reaction of potassium  tert -butoxide with ethyl bromide. The process is Williamson synthesis.This reaction follows  S_{N}{2}  mechanism.Option D is correct.

Question 4

Phenol on treatment with conc.  HNO_{3}  gives:

Accepted Answer

With concentrated nitric acid, phenol is converted to 2,4,6-trinitrophenol. The product is commonly known as picric acid. The yield of the reaction product is poor.Nowadays picric acid is prepared by treating phenol first with concentrated sulphuric acid which converts it to phenol-2,4-disulphonic acid, and then with concentrated nitric acid to get 2,4,6-trinitrophenol. Option A is correct.

Alcohols, Phenols And Ethers