Question

On an industrial scale, $H_2{O}_2$ is prepared by auto - oxidation of:

• A. 2- Ethylanthraquinol
• B. 1- Ethylanthraquinol.
• C. 1-Ethylanthraquinone.
• D. All of the above.

Answer 1

The correct option is A 2- Ethylanthraquinol

(I) 2-Ethyl anthraquinone is reduced to 2-ethyl anthraquinol by $H_2$​ in the presence of palladium.
(II) This 2-ethyl anthraquinol is oxidised by air to 2-ethyl anthrequinone again. Then $H_2{O}_2$​ (20% solution) forms.

Theory :


Hydrogen Peroxide:
It is non linear, non planar.
It has an open book structure.
$-O-O-$ linkage is called peroxy linkage.
In solid phase, the $OH$ bond length is 98.8 pm and $-O-O-$ bond length is 145.8 pm. In the gas phase, the $OH$ bond length is 95.0 pm and $-O-O-$ bond length is 147.5 pm.
Preparation:
Laboratory method:
Prepared by Merck’s process: Calculated amounts of sodium peroxide is added to ice cold dilute (20%) solution of $H_{2}S{O}_4$.
$N{a}_2{O}_2+H_{2}S{O}_4\to N{a}_{2}S{O}_4+H_2{O}_2$
Action of $H_{2}S{O}_4$ or phosphoric acid on hydrated barium peroxide:
$\underset{\text{Barium peroxide}}{Ba{O}_2.8H_{2}O+H_{2}S{O}_4}\to BaS{O}_4\downarrow +H_2{O}_2+8H_{2}O$
$3Ba{O}_2+2H_{3}P{O}_4\to B{a}_3(P{O}_4{)}_2+3H_2{O}_2$
$B{a}_3(P{O}_4{)}_2+3H_{2}S{O}_4\to 3BaS{O}_4+2H_{3}P{O}_4$
Industrial method:
Prepared by the electrolysis of 50% $H_{2}S{O}_4$ solution: In a cell, peroxydisulfuric acid is formed at the anode.
$2H_{2}S{O}_4\stackrel{\text{Electrolysis}}{\to }\underset{\text{Peroxy disulphuric acid}}{H_2{S}_2{O}_8\left(aq\right)}+H_2\left(g\right)$
Peroxy disulphuric acid is hydrolysed with water.
$H_2{S}_2{O}_8+2H_{2}O\to 2H_{2}S{O}_4+H_2{O}_2$
By redox process:
Industrially $H_2{O}_2$ is prepared by the auto-oxidation of 2-alkyl anthraquinols
The net reaction is the catalytic union of $H_2$ and $O_2$ to give $H_2{O}_2$