Ammonia reacts with acetyl chloride (CH3 COCl) to give acetamide (CH3 CONH2). Identify the bonds

step 1 In this problem, it says ammonia reacts with acetyl chloride to give acetamide. Identify the bon

Ammonia reacts with acetyl chloride (CH3 COCl) to give...

Ammonia reacts with acetyl chloride $\left(\mathrm{CH}_{3} \mathrm{COCl}\right)$ to give acetamide $\left(\mathrm{CH}_{3} \mathrm{CONH}_{2}\right)$. Identify the bonds broken and formed in each step of the reaction, and draw curved arrows to represent the flow of electrons in each step.

Key Concepts

Leaving Group Behavior

A key aspect of nucleophilic acyl substitution is the role of the leaving group. In this reaction, chloride ion serves as a good leaving group, meaning it can depart readily from the tetrahedral intermediate when the carbonyl is reformed. The ability of a group to leave is determined by its stability after departure; chloride is effective because it stabilizes the negative charge well in solution.

Curved Arrow Formalism

Curved arrow formalism is a tool used in organic chemistry to depict the movement of electrons during chemical reactions. Each curved arrow indicates the flow of an electron pair from a bond or lone pair to an electron-deficient site. This notation is essential for visualizing mechanistic steps such as the nucleophilic attack and the formation and breaking of bonds in the tetrahedral intermediate during the acyl substitution process.

Electrophilic Carbonyl Carbon

The carbonyl carbon in acyl chlorides is highly electrophilic due to the electron-withdrawing effect of both the oxygen and the chlorine attached to it. This electrophilicity makes it susceptible to attack by nucleophiles like ammonia, a property that is crucial for initiating the nucleophilic acyl substitution mechanism. Understanding this concept is important for predicting the behavior of carbonyl compounds in various reaction scenarios.

Nucleophilic Acyl Substitution

In this reaction, the mechanism involves a nucleophilic acyl substitution, where a nucleophile (ammonia) attacks the electrophilic carbonyl carbon of the acyl chloride. The process begins with the formation of a tetrahedral intermediate followed by the loss of the leaving group, typically chloride. This mechanism is fundamental in organic chemistry for transforming acyl derivatives into amides, esters, carboxylic acids, and other functional groups.

Tetrahedral Intermediate

The tetrahedral intermediate is a short-lived species formed when the nucleophile adds to the carbonyl carbon, temporarily disrupting the carbonyl double bond. This intermediate is key to understanding the reaction mechanism as it highlights the stepwise nature of the bond formation (new C–N bond) and bond breaking (C–Cl bond) processes before re-establishing a carbonyl or its equivalent, ultimately leading to product formation.

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