Alcohols, Phenols and Ethers

Which of the following is correct?

1. On reduction, any aldehyde gives secondary alcohol.
2. Reaction of vegetable oil with H2SO4 gives glycerine
3. Alcoholic iodine with NaOH gives iodoform.
4. Sucrose on reaction with NaCl gives invert sugar.

Answer

(3) Alcoholic iodine with NaOH gives iodoform.

Solution

(1) Incorrect: reduction of an aldehyde gives a primary alcohol, RCHO H2/Pd RCH2OH.

(2) Incorrect: glycerol is obtained by alkaline hydrolysis (saponification) of oils and fats, not by treating them with H2SO4.

(3) Correct: as per NCERT, ethanol (alcoholic solution) heated with iodine and NaOH gives a yellow precipitate of iodoform:

CH3CH2OH + 4I2 + 6NaOH CHI3 + HCOONa + 5NaI + 5H2O

(4) Incorrect: invert sugar is formed by hydrolysis of sucrose with dilute acid or the enzyme invertase, not with NaCl.

Answer: (3)