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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Benzoxazine Formation Mechanism Evaluation by Direct Observation of Reaction Intermediates

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Ribeiro, Francisco W. M. [1] ; Rodrigues-Oliveira, Andre F. [1] ; Correra, Thiago C. [1]
Total Authors: 3
[1] Univ Sao Paulo, Cidade Univ, Inst Chem, Dept Fundamental Chem, Av Prof Lineu Prestes, 748, Cidade Univ, BR-05508000 Sao Paulo, SP - Brazil
Total Affiliations: 1
Document type: Journal article
Source: Journal of Physical Chemistry A; v. 123, n. 38, p. 8179-8187, SEP 26 2019.
Web of Science Citations: 0

Benzoxazine formation is a fundamental step in the preparation of polybenzoxazine resins, and a detailed description of the mechanism governing the formation of benzoxazine and side products is vital for improving the properties and performance of these resins. Determination of the nature and properties of reaction intermediates is not trivial. Therefore, a Mannich-type condensation of aniline, formaldehyde, and phenol was evaluated as a potential method to form benzoxazine. Coupling positive mode electrospray ionization mass spectrometry (ESI(+)-MS) with infrared multiple photon dissociation (IRMPD) spectroscopy allowed unambiguous determination of an iminium-based mechanism and the direct observation of iminium intermediates. The benzoxazine formation mechanism was indirectly confirmed by the observation of side products that are relevant to the polymerization step, and directly confirmed by the identification of four distinct reaction intermediates that were completely characterized by IRMPD spectroscopy. The benzoxazine monomer was also shown to undergo isomerization under standard ESI-MS analysis conditions, suggesting the presence of a mixture of three isomers during their usual ESI-MS analysis. (AU)

FAPESP's process: 14/15962-5 - Reaction mechanism of asymmetric catalysts by mass spectrometry and gas-phase vibrational ion spectroscopy
Grantee:Thiago Carita Correra
Support type: Research Grants - Young Investigators Grants
FAPESP's process: 15/08539-1 - Multi-User Equipment approved in grant 2014/15962-5: ion trap mass spectrometer modified to perform infrared vibrational spectroscopy (IRMPD)
Grantee:Thiago Carita Correra
Support type: Multi-user Equipment Program
FAPESP's process: 17/18485-1 - Mechanistic studies of haloamination reactions promoted by metallic and organic catalysts
Grantee:Francisco Wanderson Moreira Ribeiro
Support type: Scholarships in Brazil - Doctorate