(a) Account for the following: (i) ClCH2COOH is a stronger acid than CH3COOH. (ii) Carboxylic acids do not give reactions of the carbonyl group. (b) Write the chemical equations to illustrate the following name reactions: (i) Rosenmund reduction (ii) Cannizzaro's reaction (c) Out of CH3CH2COCH3 and CH3CH2CH2COCH3, which give iodoform test?

(a)(i) Because of the -I effect of the Cl atom in ClCH2COOH and the +I effect of the CH3 group in CH3COOH, the electron density in the O-H bond in ClCH2COOH is much lower than in CH3COOH. As a result, the O-H bond in ClCH2COOH is much weaker than in CH3COOH; therefore, it loses a proton more easily than CH3COOH. Hence, ClCH2COOH is a stronger acid than CH3COOH. (ii) Carboxylic acids are resonance hybrids of the following structures:

[Structures would be represented here using chemical drawing if this were a full-fledged answer system. A textual description is not sufficient to represent the structures accurately.]

Similarly, a carbonyl group of aldehydes and ketones may be regarded as a resonance hybrid of the following structures:

[Structures would be represented here using chemical drawing if this were a full-fledged answer system. A textual description is not sufficient to represent the structures accurately.]

Because of the contribution of structure (IV), the carbonyl carbon in aldehydes and ketones is electrophilic. On the other hand, the electrophilic character of the carboxyl carbon is reduced due to the contribution of structure (ii). As the carbonyl carbon of the carboxyl group is less electropositive than the carbonyl carbon in aldehydes and ketones, therefore, carboxylic acids do not give nucleophilic addition reactions of aldehydes and ketones. (b)(i) [Chemical equation for Rosenmund reduction would be represented here using chemical drawing and text if this were a full-fledged answer system.] (ii) [Chemical equation for Cannizzaro's reaction would be represented here using chemical drawing and text if this were a full-fledged answer system.] (c) CH3CH2COCH3