Which of the statements is correct about the mechanism of the following reaction? A. DMSO reacts with the alcohol initially to give which reacts with (COCl2) B. (COCl2) reacts with the alcohol initially to give which reacts with DMSO C. DMSO reacts with (COCl)2 initially to give which reacts with the alcohol D. (COCl2) reacts with DMSO initially to give which reacts with the alcohol

The correct answer is: A. DMSO reacts with the alcohol initially to give which reacts with (COCl2).

The reaction is a nucleophilic substitution reaction. The nucleophile is the alcohol, and the electrophile is the carbon atom in the carbonyl group of (COCl2). The first step is the formation of a tetrahedral intermediate by attack of the nucleophile on the electrophile. In the second step, the leaving group, chloride, leaves, and the product is formed.

Here is a more detailed explanation of each option:

• Option A: DMSO reacts with the alcohol initially to give which reacts with (COCl2). This is the correct answer. The first step is the formation of a tetrahedral intermediate by attack of the nucleophile on the electrophile. In the second step, the leaving group, chloride, leaves, and the product is formed.
• Option B: (COCl2) reacts with the alcohol initially to give which reacts with DMSO. This is not the correct answer. The alcohol is the nucleophile, and (COCl2) is the electrophile. The first step should be the attack of the nucleophile on the electrophile, not the other way around.
• Option C: DMSO reacts with (COCl)2 initially to give which reacts with the alcohol. This is not the correct answer. The correct formula for (COCl2) is $\ce{COCl2}$, not $\ce{COCl}$.
• Option D: (COCl2) reacts with DMSO initially to give which reacts with the alcohol. This is not the correct answer. The alcohol is the nucleophile, and (COCl2) is the electrophile. The first step should be the attack of the nucleophile on the electrophile, not the other way around.