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Reactivity and reaction pathways of alkylalkoxybenzene radical cations. Part 3. Effects of 2-alkyl substituents on the relative importance of ring-substitution over deprotonation of 2-alkyl-1,4-dimethoxybenzene radical cations

Reactivity and reaction pathways of alkylalkoxybenzene radical cations. Part 3. Effects of... One-electron oxidation of 2-alkyl-1,4-dimethoxybenzenes 1a-f (2-alkyl=Me, Et, i-Pr, cy-C3H5CH2, PhCH2 and t-Bu) by 4-nitrobenzoyl peroxide 2 and pentaflurobenzoyl peroxide 3 was proved by the observation of great acceleration of decomposition of the peroxides at room temperature, the detection of the corresponding radical cations 1 +• a-f and product analysis. The product studies have disclosed that under the conditions employed (in acetonitrile at 40°C), the reaction pathways of the radical cations are greatly dependent on the nature of 2-alkyl substituents: Ring-4-nitrobenzoloxylation product at C 5 and C 6 were obtained exclusively in the reactions of the donors with aliphatic 2-alkyl substituents bearing at least one α-hydrogen atom, such as 1a, 1b, 1c and 1d; whereas in the case of 1e (with 2-benzyl group), both ring-substitution at C 5 (4e) and C 6 (5e) and deprotonation/4-nitrobenzoloxylation products 8e were isolated; from the donor without α-hydrogen atom, 1f, de-t-butylation products 12 and t-butyl 4-nitrobenzoate 13 were incorporated with ring-substitution at C 5 (4f) and C 6 (5f). Furthermore, the product distribution (4 over 5) is also affected by the bulkiness of 2-alkyl group. For all the electron-transfer reactions, large amounts of the benzoic acid (4-NO2-C6H4COOH or C6F5COOH) were generated and trace amounts of de-methylation product (2-alkyl-1,4-benzoqinones 6) were also detected by 1H NMR. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Research on Chemical Intermediates Springer Journals

Reactivity and reaction pathways of alkylalkoxybenzene radical cations. Part 3. Effects of 2-alkyl substituents on the relative importance of ring-substitution over deprotonation of 2-alkyl-1,4-dimethoxybenzene radical cations

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References (14)

Publisher
Springer Journals
Copyright
Copyright © 2000 by Springer
Subject
Chemistry; Catalysis; Physical Chemistry; Inorganic Chemistry
ISSN
0922-6168
eISSN
1568-5675
DOI
10.1163/156856700X00615
Publisher site
See Article on Publisher Site

Abstract

One-electron oxidation of 2-alkyl-1,4-dimethoxybenzenes 1a-f (2-alkyl=Me, Et, i-Pr, cy-C3H5CH2, PhCH2 and t-Bu) by 4-nitrobenzoyl peroxide 2 and pentaflurobenzoyl peroxide 3 was proved by the observation of great acceleration of decomposition of the peroxides at room temperature, the detection of the corresponding radical cations 1 +• a-f and product analysis. The product studies have disclosed that under the conditions employed (in acetonitrile at 40°C), the reaction pathways of the radical cations are greatly dependent on the nature of 2-alkyl substituents: Ring-4-nitrobenzoloxylation product at C 5 and C 6 were obtained exclusively in the reactions of the donors with aliphatic 2-alkyl substituents bearing at least one α-hydrogen atom, such as 1a, 1b, 1c and 1d; whereas in the case of 1e (with 2-benzyl group), both ring-substitution at C 5 (4e) and C 6 (5e) and deprotonation/4-nitrobenzoloxylation products 8e were isolated; from the donor without α-hydrogen atom, 1f, de-t-butylation products 12 and t-butyl 4-nitrobenzoate 13 were incorporated with ring-substitution at C 5 (4f) and C 6 (5f). Furthermore, the product distribution (4 over 5) is also affected by the bulkiness of 2-alkyl group. For all the electron-transfer reactions, large amounts of the benzoic acid (4-NO2-C6H4COOH or C6F5COOH) were generated and trace amounts of de-methylation product (2-alkyl-1,4-benzoqinones 6) were also detected by 1H NMR.

Journal

Research on Chemical Intermediates – Springer Journals

Published: Jul 7, 2009

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