Are mezoionic compounds aromatic?
Article Abstract:
Experimental evidence, including X-ray diffraction studies, related to the structure and character of mesoionic compounds has been re-examined along with results of theoretical studies. Experimental data were accumulated over a period of more than 100 years. It appears that these compounds are not aromatic, but five-membered heterocyclic betaines having one or more side chains with an alpha-atom in the ring plane and dipole moment on the order of 5 D. Electrons are not localized; they range over the two regions, being separated by single bonds, in essence. Pi-charges are negative where the alpha-atom of the side chain is; they are positive where the LUMO, as opposed to the HOMO, is.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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Dephosphorylation and aromatic nucleophilic substitution in nonionic micelles: the importance of substrate location
Article Abstract:
Reactions of OH and F negative ions, with p-nitrophenyl diphenyl phosphate (pNPDPP) are inhibited by very dilute polyoxyethylene and dodecyl glycol. At concentrations above the critical micelle concentration rate constants are independent of surfactant concentrations. Low-charge-density anions, that is, ClO4, inhibit, and low-charge-density cations, that is, (n-C7H15)N, speed reactions, probably by effects in the palisade layer on concentrations of nucleophiles. Aromatic nucleophilic substitution and desphosphorylation have been studied in nonionic micelles with an eye to importance of substrate location.
Publication Name: Canadian Journal of Chemistry
Subject: Chemistry
ISSN: 0008-4042
Year: 1998
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