Question

1]
30. 2075 GIE Q.No. 29 An organic compound gives H2 gas with
Sodium metal. On treatment with alkaline iodine gives yellow
ppt and on oxidation with CeO2/H+ form an aldehyde
(C2H4O). Name, the compound and write reactions involved.

Answer 1

Explanation:

Given -

• An organic compound gives H₂ gas with Na
• On treatment with alkaline iodine it gives yellow ppt.
• On oxidation with CrO₃/H⁺ forms an aldehyde (C₂H₄O)

To Find -

• Name the compound and write the reaction involved

Now,

Let A be the organic compound.

Then,

1. A + Na → + H₂↑
2. A + I₂ → CHI₃ (yellow ppt.)
3. A + CrO₃ + H⁺ → C₂H₄O

Now,

Here we see that compound A reacts with chromic oxide (CrO₃) in the presence of acidic medium gives aldehyde.

• Functional group of aldehyde = —CHO

And It forms only 2 Carbon aldehyde it means, It is Ethanal (CH₃CHO).

Compound A reacts with chromic oxide (CrO₃) in the presence of acidic medium gives ethanal.

It means,

We know that 1° alcohol on oxidation gives aldehyde.

Here it gives 2 Carbon aldehyde.

It means,

Here 2 Carbon and 1° alcohol is used.

Now,

Its cleared that Compound A is Ethanol.

Reaction Involved -

1. CH₃CH₂OH + Na → CH₃CH₂O⁻Na⁺ + H₂↑
2. CH₃CH₂OH + I₂ + OH⁻ → CHI₃↓ + HCOO⁻ + HI + H₂O
3. CH₃CH₂OH + CrO₃ + H⁺ → CH₃CHO