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Rate-limiting proton-transfer in the σ-adduct forming reactions of 1,3,5-trinitrobenzene and 4-nitrobenzofuroxan with substituted anilines in dimethyl sulfoxide

Asghar, B.H.M.; Crampton, M.R.

Authors

B.H.M. Asghar

M.R. Crampton



Abstract

Kinetic and equilibrium results are compared for the reactions in dimethyl sulfoxide of 1,3,5-trinitrobenzene, 1, and 4-nitrobenzofuroxan, 4, with a series of substituted anilines in the presence of Dabco or in, some cases, quinuclidine. pKa values for the corresponding anilinium ions are reported. The reactions of 1 and 4 are likely to proceed through nucleophilic attack by the aniline to yield zwitterionic intermediates which may transfer an acidic proton to the bases present to yield the anionic adducts 9 or 12 respectively. In the formation of 9 from 1 the proton transfer step is rate-limiting; however, the slower interconversion of 4 and its zwitterion leads to only partial rate-limiting proton transfer in the formation of 12. Results with substituted anilines including 2-substituted and N-methyl aniline indicate that steric effects are not a major factor in determining rates of proton-transfer in these systems. Contrary to previous reports no evidence was found for a strong interaction between 1 and Dabco in DMSO.

Citation

Asghar, B., & Crampton, M. (2005). Rate-limiting proton-transfer in the σ-adduct forming reactions of 1,3,5-trinitrobenzene and 4-nitrobenzofuroxan with substituted anilines in dimethyl sulfoxide. Organic and Biomolecular Chemistry, 3(21), 3971-3978. https://doi.org/10.1039/b511644a

Journal Article Type Article
Publication Date Jan 1, 2005
Deposit Date Sep 21, 2007
Journal Organic and Biomolecular Chemistry
Print ISSN 1477-0520
Electronic ISSN 1477-0539
Publisher Royal Society of Chemistry
Peer Reviewed Peer Reviewed
Volume 3
Issue 21
Pages 3971-3978
DOI https://doi.org/10.1039/b511644a