JEE Main · 2024 · 05 Apr 2024 · Shift 2 · Aldehydes Ketones and Carboxylic Acids

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In the Claisen-Schmidt reaction to prepare 351 g of dibenzalacetone using 87 g of acetone, the amount of benzaldehyde required is ______ g. (Nearest integer)

Answer: 318

Solution

Claisen–Schmidt condensation:

2 P h C H O + C H_{3} C O C H_{3} N a O H P h C H = C H - C O - C H = C H P h

(dibenzalacetone), i.e. 2 mol benzaldehyde per mol product.
Molar mass of dibenzalacetone

= 234

g/mol, so

351

= 1.5

mol (consistent with

87

g acetone

= 1.5

mol).
Benzaldehyde required

= 2 \times 1.5 = 3

mol

= 3 \times 106 = 318

JEE Main · 2024 · 05 Apr 2024 · Shift 2 · Integer answer

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