Explain the following reaction: Rosenmund reduction

Acyl chlorides are reduced with hydrogen in boiling xylene in the presence of palladium supported over barium sulphate catalyst to give aldehydes. This reaction is called Rosenmund reduction. Example:

Identify A , B and C in the following sequence of reactions: CH 3 COOH + NH 3 ⇌ CH 3 CO O - N + H 4 → ∆ A → ∆ H 3 O + B → Br 2 / red P C

Reaction of CH 3 COOH with NH 4 OH , followed by heating at high temperature give amides. CH 3 COOH + NH 3 ⇔ CH 3 CO O - NH 4 + → ∆ CH 3 CONH 2 + H 2 O Hydrolysis of an amide in acid solution actually gives a carboxylic acid and the salt of ammonia or an amine. HVZ reaction is a halogenation reaction i.e. addition reaction which adds one or more halogen to the compound. It halogenated carboxylic acids at the alpha carbon position in presence of Bromine and red phosphorus. CH 3 CONH 2 → H 3 O + CH 3 COOH + NH 3 HVZ reaction can go on till there is replacable acidic hydrogen present in the α group of the carboxylic acid. CH 3 COOH + Br 2 → P / H 2 O BrCH 2 COOH + HBr

Give the structural formula and IUPAC name of the product formed by the reaction of propanone with CH 3 MgBr in dry ether, followed by hydrolysis.

The structural formula and IUPAC name of the product formed by the reaction of propanone or acetone with CH 3 MgBr in dry ether, followed by hydrolysis are 2 - methylpropan - 2 - ol and tertiaty-butyl alcohol respectively.

Explain Haloform reaction.

The haloform reaction is a chemical reaction where a haloform CHX 3 , x = halogen is produced by the full halogenation of a methyl ketone ( RCOCH 3 , where R can be either a hydrogen atom, an alkyl or an aryl group) in the presence of a base. 2 NaOH + Cl 2 → NaOCl + NaCl CH 3 COCH 3 + 3 NaOCl → CH 3 COONa + CHCl 3 Haloform + 2 NaOH

Identify the products and give the name of the following reaction: C 6 H 5 CHO → ∆ conc . NaOH Products

The disproportionation reaction of aldehydes without α-hydrogens in presence of a strong base to give an alcohol and a carboxylic acid is called Cannizzaro reaction. One molecule of aldehyde is reduced to the corresponding alcohol, while a second one is oxidized to the carboxylic acid. 2 C 6 H 5 CHO → ∆ NaOH C 6 H 5 CH 2 OH + C 6 H 5 COONa

Give a chemical test to distinguish between propanal and propanone.

Iodoform test: Aldehydes and ketones having at least one methyl group linked to the carbonyl carbon atom respond to iodoform test. They are oxidised by sodium hypoiodite ( NaOI ) to give iodoforms. Propanone being a methyl ketone responds to this test, but propanal does not. CH 3 COCH 3 Propanone + 3 NaOI → CH 3 COONa + CHI 3 + 2 NaOH CH 3 CH 2 CHO Propanal + 3 NaOI → No reaction

How would you account for: Addition reaction of sodium hydrogen sulphite is useful for separation and addition of aldehydes.

Sodium hydrogen sulphite adds to aldehydes and ketones to form the additional products. The position of the equilibrium lies largely to the right-hand side for most aldehydes and to the left for most ketones due to steric reasons. The hydrogen sulphite addition compound is water-soluble and can be converted back to the original carbonyl compound by treating it with dilute mineral acid or alkali. Therefore, these are useful for the separation and purification of aldehydes.

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EMBIBE CHAPTER WISE PREVIOUS YEAR PAPERS FOR CHEMISTRY>Chapter -1 - Aldehydes, Ketones and Carboxylic Acids>Kerala Board-2018>Q 1

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12th Kerala Board

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Aromatic aldehydes undergo electrophilic substitution reactions. Write the nitration reaction of benzaldehyde with chemical equation.

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