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Nukleofilowe podstawienie wodoru w nitroarenach. Proces analogiczny i komplementarny do podstawienia elektrofilowego

Mąkosza M.

Wiadomości Chemiczne

2011

[Z] 65, 9-10

795-819

Nucleophiles add to electron-deficient arenes, also those containing halogens, initially in positions occupied by hydrogen to form óH adducts. This addition is faster than addition in similarly activated positions occupied by halogens. Formation of the óH adducts is a reversible process, thus they dissociate and slower addition in positions occupied by halogens results in formation of óH adducts followed by fast departure of X– to form products of nucleophilic substitution of halogen, SNAr. In the review it is shown that there are a few ways for fast further conversion of initially formed óH adducts into products of nucleopilic substitution of hydrogen such as oxidative substitution, vicarious substitution, etc. Since formation of óH adducts is faster than óH adducts and the former undergo fast transformations into products of nucleophilic substitution of hydrogen we should accept than this is the major, primary reaction whereas conventional nucleophilic substitution of halogens, SNAr reaction “ipso” substitution is just a secondary process. In modern textbooks only SNAr reactions are discussed whereas nucleophilic substitution of hydrogen is not mentioned, thus it is necessary to introduce proper corrections in textbooks and teaching of this chapter of chemistry of arenes.

Vicarious Nucleophilic Substitution of Hydrogen in 2,4-Dinitroanilines and Cyanonitroanilines

Mąkosza M., Voskresensky S., Białecki M., Kwast A.

Polish Journal of Chemistry

1999

Vol. 73, nr 12

1969-1977

Orientation of the VNS reaction in nitroaniline derivatives is mostly governed by the conjugation between the nitro groups and the amino group, which could be also deprotonated under the reaction conditions.