Nature of the active center in the cyclotrimerization of isocyanates catalyzed by the tertiary amine—α-oxide—protondonor system |
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Authors: | L. I. Komarova Ts. M. Frenkel' A. E. Shvorak V. A. Pankratov B. N. Lokshin |
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Affiliation: | (1) A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, 28 ul. Vavilova, 117813 Moscow, Russian Federation |
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Abstract: | The structure of the dimethylbenzylamine (DMBA)—phenylglyc idyl ether (PGE)—phenol complex was studied by IR and1H NMR spectroscopy under various conditions of its formation. The active catalyst in the cyclotrimerization of isocyanates is a complex of composition DMBA : PGE : PhOH = 1 : 1 : 2, in which the oxygen atom of the zwitter-ion PhCH2N+Me2CH2CH(O–)CH2OPh that forms after opening, of the epoxide cycle is bound to two phenol molecules by a very strong hydrogen bonds. In this complex, the oxygen atom of both the zwitter-ion and the phenolate anion can be catalytic centers. Two schemes of the cyclotrimerization of isocyanate in the presence of the aforementioned catalytic system are suggested, depending on whether the catalytic complex has time to form or not.For Part I, see Ref. 1.Deceased.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1662–1668, July, 1996. |
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Keywords: | cyclotrimerization of isocyanates catalytic complex hydrogen bonds active center |
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