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Hydroxy‐ and Methoxybenzene Derivatives with Benzenediazonium Salts ― Chemical Behavior and Tautomeric Problems
Author(s) -
Micheletti Gabriele,
Boga Carla,
Forlani Luciano,
Del Vecchio Erminia,
Zanicola,
Mazzanti Andrea,
Monari Magda
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201601393
Subject(s) - chemistry , tautomer , organic chemistry , computational chemistry
The azo‐coupling reactions between 4‐nitrobenzenediazonium tetrafluoroborate and a series of benzene derivatives bearing at least one electron‐donating hydroxy or methoxy substituent have been studied. Depending on the nucleophile and its relative ratio with the diazonium salt, it was possible to obtain mono‐ and disubstituted products as well as a trisubstituted product for phloroglucinol. The reactions between 3,5‐diaminoanisole or 3,5‐diaminophenol derivatives and 2 equiv. of diazonium salt gave the monosubstituted product in the first case and a diadduct in the second case; X‐ray diffraction analysis revealed a highly symmetric structure for the latter. The different behaviors of hydroxy‐ and methoxy‐substituted compounds was particularly evident for phloroglucinol and 1,3,5‐trimethoxybenzene and may be rationalized on the basis of the different electronic effects of the substituents. The propensities of the aromatic rings to undergo H/D exchange reactions were investigated for a series of substrates, and a comparison of the results obtained provided new insights into this phenomenon and permitted a better explanation of the findings reported here; a new particular interaction competes with the formation of a proton–phloroglucinol σ complex.