Give the plausible explanation for the following: Glucose doesn’t give 2 , 4 - DNP test.

Despite the fact that glucose has a free aldehydic group in its open chain structure, it does not yield the 2,4-DNP test, which is a characteristic reaction of aldehydes, i.e. – CHO groups. This is because the cyclic hemiacetal form of glucose exists in equilibrium with only a small amount of the open chain form. As the open-chain form's concentration is so low and its reactions with 2,4-DNP are reversible, the 2,4-DNP adduct is rarely observed. Also, glucose doesn’t give 2,4-DNP test because the – CHO group in glucose is involved in hemiacetal formation and thus it is not free.

Give the structures of A and B in the following sequence of reactions: CH 3 COOH → ∆ NH 3 A → NaOBr B

In the first step of the reaction, acetic acid reacts with ammonia to form ammonium acetate which on heating undergoes dehydration to form acetamide. It is a neutralisation reaction and is represented as follows: CH 3 COOH → NH 3 CH 3 COONH 4 + → ∆ CH 3 CONH 2 + H 2 O In the second step, the acetamide undergoes Hoffmann bromamide degradation reaction. Hoffmann developed a method for preparation of primary amines by treating an amide with bromine in an aqueous or ethanolic solution of sodium hydroxide. In this degradation reaction, migration of an alkyl or aryl group takes place from carbonyl carbon of the amide to the nitrogen atom. The reaction of acetamide with NaOBr forms methylamine and is represented as: CH 3 CONH 2 → NaOBr CH 3 NH 2 Methylamine

What happens when benzene is treated with CH 3 COCl in presence of anhydrous AlCl 3 ?

In the presence of anhydrous aluminium chloride, benzene reacts with acetyl chloride to form acetophenone. The reaction is a Friedel-craft reaction in which the aromatic ring gains an acyl group. Friedel-craft acylation involves the addition of acid chloride using a Lewis acid catalyst, aluminium chloride AlCl 3 . The major product of the Friedel-craft acylation reaction is a ketone. The conversion of benzene into acetophenone is an electrophilic substitution, where an acyl group is attached to the benzene ring. The Lewis acid catalyst initially combines with the acyl chloride to produce a complex in which the acyl chloride loses its chloride ion and forms the acylium ion RCO + , which acts as an electrophile and stabilises through resonance. The reaction is as follows: C 6 H 6 + CH 3 COCl → ∆ Anhyd . AlCl 3 C 6 H 5 COCH 3 + HCl

Explain why pK a value of 4 -nitrobenzoic acid is lower than that of benzoic acid?

Due to the electron withdrawing nature of the nitro group, the conjugate carboxylate ion will be highly stabilised in the case of 4 - Nitrobenzoic acid. Due to which it is more acidic than benzoic acid and a thus a lower pK a value.

Aromatic carboxylic acids do not undergo Friedel-Crafts reaction.

Friedel-Crafts reaction is an organic coupling reaction involving an electrophilic aromatic substitution that is used for the attachment of substituents to aromatic rings. The carboxyl group of an aromatic carboxylic acid is a deactivating group and will not favour electrophilic substitution reaction.

How do you convert the following ? Toluene to Benzoic acid

Vigorous oxidation of toluene with KMnO 4 , KOH , heat, followed by acidic hydrolysis gives benzoic acid as the final product.

Write chemical equations for the following reaction : Benzoyl chloride is hydrogenated in presence of Pd / BaSO 4 .

Acyl chloride (acid chloride) is hydrogenated over catalyst, palladium on barium sulphate. This reaction is called Rosenmund reduction.Thus, when Benzoyl chloride is hydrogenated in presence of Pd / BaSO 4 , benzaldehyde is formed.

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How do you convert the following?
Ethanal to Propanone

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