Solvolysis of substituted benzoyl chlorides in nonionic and mixed micellar solutions
P Campos-Rey1, C Cabaleiro-Lago, P Hervés
1Department of Physical Chemistry, Faculty of Chemistry, University of Vigo, 36310 Vigo, Spain.
Abstract:
The solvolysis of substituted benzoyl chlorides is sensitive both to substituent electronic effects and to medium effects. The solvolysis reactions of substituted benzoyl chlorides have been analyzed in the presence of nonionic micelles. The reaction is inhibited or catalyzed depending on the reaction mechanism, dissociative or associative, respectively. The micellar effects observed can be related to the low water content and low polarity of the interface as well as an increase of the nucleophilic character of the interfacial water. Moreover, the effect of the micellar surface charge on the solvolysis mechanism with high associative character was systematically studied. Mixed micelles of nonionic-ionic surfactants with a variable ionic content were prepared and characterized regarding charge and polarity. A correlation between the net charge of the micelles and the rate constants at the micellar interface was observed. The results suggest that the transient state for this mechanism is highly stabilized in a positively charged environment while the negative surface given by anionic micelles strongly inhibit the solvolysis reaction.
Related Concept Videos
Electrophilic Aromatic Substitution: Sulfonation of Benzene
Electrophilic Aromatic Substitution: Chlorination and Bromination of Benzene
Micelles
Hydrolysis of Chlorobenzene to Phenol: Dow Process
Acid Halides to Carboxylic Acids: Hydrolysis
As shown below, the mechanism involves a nucleophilic attack by water at the carbonyl carbon to form a tetrahedral intermediate. This is followed by the reformation of the carbon–oxygen π bond along with the departure of a halide ion. A final proton transfer step yields carboxylic acid...
Reactions at the Benzylic Position: Halogenation


