Compound (I) reacts with methanol to produce intermediate (II) and chloride ions. Which one of the following mechanisms is correct?

Question

BlackTom AI · Accepted Answer

This question asks you to evaluate which mechanistic sequence best describes the reaction of compound I with methanol to give intermediate II and chloride ions.
First, consider what is happening: a carbonyl chloride (acetyl chloride-type) plus methanol can proceed via nucleophilic attack by alcohol on the acyl carbon, forming a tetrahedral intermediate, followed by collapse to give an ester (as intermediate II) and release of chloride as Cl−. You should look for a mechanism where methanol acts as a nucleophile attacking the carbonyl carbon, the leaving group is Cl−, and the intermediate resembles a protonated or neutral ester formation prior to final product formation.
Option A: The arrows depict methanol attacking after some immediate rearrangement and the chloride leaving in a way that seems inconsistent with a straightforward acyl substitution by a neutral alcohol. The depicted intermediate structure and charge distribution may not align with a simple acyl substitution mechanism, and the sequence of bond-making and bond-breaking does not clearly show formation of a stable tetrahedral intermediate that then collapses to yield the ester plus chloride. This makes the pathway less convincing as a direct esterification mechanism.
Option B: Here, methanol attacks the carbonyl carbon of I, generating a tetrahedral intermediate in which the methoxy group is forming a new C–O bond while the C=O is converted to a negatively charged oxygen. The leaving group is Cl− as the carbonyl collapses, giving the ester (II) and Cl−. This sequence matches the classic acyl substitution (nucleophilic acyl substitution) mechanism by an alcohol, producing an ester and chloride ion in the expected manner. The charge distribution and connectivity in the intermediate are consistent with a tetrahedral intermediate followed by chloride departure.
Option C: The depicted flow may indicate a similar attack but with a different orientation of electrons or a misplacement of the leaving group that does not correspond to the conventional acyl substitution pathway. If the intermediate shows an unusual arrangement or if the leaving group departure occurs prematurely, it would not accurately portray the standard progression from tetrahedral intermediate to ester plus Cl−. This makes C less consistent with the straightforward mechanism.
Option D: Although it appears to involve nucleophilic attack by methanol, the arrangement of electrons in the intermediate and the subsequent step may misrepresent which atom bears the positive or negative charges, or how the leaving group departs. If the sequence does not reflect the canonical acyl substitution (addition–elimination) pattern, it’s not the best fit for this reaction.
In summary, when comparing the options, you should look for the option that shows methanol adding to the carbonyl to form a tetrahedral intermediate, followed by collapse with chloride as the leaving group, yielding the ester (II). Option B best aligns with this classic acyl substitution mechanism, while A, C, and D introduce inconsistencies in electron flow, intermediate structure, or leaving-group behavior that do not match the standard process for converting an acyl chloride with an alcohol into an ester and Cl−.

CHM1052 - MUM S2 2025 CHM1052 2022 practice exam 1

Compound (I) reacts with methanol to produce intermediate (II) and chloride ions. Which one of the following mechanisms is correct?

View Explanation

Log in for full answers

Similar Questions

Consider the nucleophilic substitution of ammonia to benzoyl chloride shown below. Which of the following statements is true?

Consider the reaction of ethanoyl chloride with methanol shown below. What product(s) may you expect to be formed from the reaction?

Consider the nucleophilic addition of ammonia to benzoyl chloride shown below. Which of the following statements is true?

Which of these will NOT act like a nucleophile for nucleophilic acyl substitution with an acyl halide? (select all that apply).

In a consumer society, many adults channel creativity into buying things

More Practical Tools for Students Powered by AI Study Helper

Homework AI Solver

Stylized AI Paper Writer

Plagiarism Checker Assistant

Citation AI Academic Writing Tool

In-Class Translation Assistant

AI Note Generator

AI Quiz Answers

Past Exam Questions from University Test Bank

Smart Practice Assistant

Adaptive Practice

Making Your Study Simpler