Publication Date

1967

Document Type

Dissertation/Thesis

First Advisor

Kevill, Dennis N.||Joncich, Michael J.

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Chemistry

LCSH

Quantum theory

Abstract

Investigations of the reactions of alkyl halides with silver salts in acetonitrile have given good evidence for simultaneous electrophi1ic and nucleophilic assistance being present in the rate limiting step. However, it has recently been shown that acyl halides (alkyl chloroformates) react with AgNO₃ in acetonitrile by either electrophi1ic attack or nucleophilic assistance in the rate limiting step, but not by both simultaneously. The simultaneous "push-pull" nucleophilic substitution mechanism for alkyl halides of C. G. Swain when extended to acyl halides, as previously proposed, seems to be in conflict with direct evidence. The investigations conducted here on the methanolysis of p-nitrobenzoy1 chloride in acetonitrile very strongly suggest that the simultaneous attack of two methanol molecules, previously postulated to be by one as nucleophile and one as electrophile, is rather a nucleophilic attack by one methanol molecule to form an intermediate, followed by a second methanol molecule accepting a proton to give a second intermediate which, in turn, decomposes to give products. The experimental reaction rate may then be expressed as 10⁴d [HCl]/dt = k₂[PNBC][MeOH] + k₃[PNBC] [MeOH]², the second order term appearing for cases when the solvent molecule, rather than a second methanol molecule, accepts a proton from the first intermediate. Consistent with this formulation, the reaction rate at 25.0° C. for MeOH up to approximately 1 M̲ is not affected by addition of an electrophi1ic reagent such as phenol, which would be a better electrophile than methanol. Also, added chloride ion causes a tremendous acceleration in the rate, presumable due to chloride being a stronger base than methanol in acetonitrile and acting in place of the second methanol molecule in accepting a proton form the first intermediate. The much weaker proton acceptor, perchlorate ion, causes no acceleration.

Comments

Includes bibliographical references.||Includes illustrations.

Extent

viii, 61 pages

Language

eng

Publisher

Northern Illinois University

Rights Statement

In Copyright

Rights Statement 2

NIU theses are protected by copyright. They may be viewed from Huskie Commons for any purpose, but reproduction or distribution in any format is prohibited without the written permission of the authors.

Media Type

Text

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