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Title: Electrophilic substitution reactions
Author: Lawson, Alexander Johnston
Awarding Body: University of London
Current Institution: Imperial College London
Date of Award: 1970
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The mechanistic investigations of certain electrophilic substitution reactions are briefly reviewed, with particular regard to C-nitrosation of aromatic substrates. The kinetic principles of the investigation are then outlined. An account of the C-nitrosation of a series of indoles in dilute aqueous acid is reported, in which nitrous anhydride, nitrosyl chloride, and the nitrousacidium ion are each deduced to be active electrophiles. An unusual change in the rate-determining step on variation of the basicity of the substrate is ascribed to the diffusion-controlled nature of reaction, when the reagent is either nitrosyl chloride or the nitrousacidium ion. The nitrosation of both phenol and anisole in more concentrated acid are then reported, and the results interpreted in terms of a dienone intermediate in the case of phenol. The nitrosonium ion is demonstrated to be an active nitrosating agent. Further studies are presented on the reaction of less reactive aromatic substrates with the nitrosonium ion, and the conclusion is made that the transition state of the aromatic C-nitrosation. reactions generally involves loss of a proton from the Wheland intermediate to the solvent.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available