Final answer:
The nucleophilic site in the reactants of a nucleophilic acyl substitution reaction is the carbon (C) of the carbonyl group, which becomes attacked by a nucleophile resulting in a new bond and the formations of a tetrahedral intermediate.
Step-by-step explanation:
The nucleophilic site in the reactants of a nucleophilic acyl substitution reaction is typically the carbon atom of the carbonyl group. This is because the carbon atom is electrophilic due to its partial positive charge caused by the strong electronegativity of the oxygen atom double bonded to it. During the course of the reaction, the nucleophile, which is a species with a pair of electrons to donate, attacks the positively charged carbon, forming a new bond and leading to a tetrahedral intermediate. The sequence often proceeds with the expulsion of a leaving group, after which the nucleophile has effectively substituted where the leaving group was previously attached.
In the mechanism of such reactions, the nucleophile attacks the electrophilic carbonyl C, while the weakest T-bond on the carbonyl carbon is concurrently broken. This answers the student's question that option 1, the carbon (C) of the carbonyl group, is the nucleophilic site in the reactants of a nucleophilic acyl substitution reaction.
A