Issue 34, 2014

Influence of substituent on equilibrium of benzoxazine synthesis from Mannich base and formaldehyde

Abstract

N-Substituted aminomethylphenol (Mannich base) and 3,4-dihydro-2H-3-substituted 1,3-benzoxazine (benzoxazine) were synthesized from substituted phenol (p-cresol, phenol, p-chlorophenol), substituted aniline (p-toluidine, aniline, p-chloroaniline) and formaldehyde to study influence of substituent on equilibrium of benzoxazine synthesis from Mannich base and formaldehyde. 1H-NMR and charges of nitrogen and oxygen atoms illustrate effect of substituent on reactivity of Mannich base, while oxazine ring stability is characterized by differential scanning calorimetry (DSC) and C–O bond order. Equilibrium constants were tested from 50 °C to 80 °C, and the results show that substituent attached to phenol or aniline has same impact on reactivity of Mannich base; however, it has opposite influence on oxazine ring stability and equilibrium constant. Compared with the phenol–aniline system, electron-donating methyl on phenol or aniline increases the charge of nitrogen and oxygen atoms in Mannich base. When the methyl group is located at para position of phenol, oxazine ring stability increases, and the equilibrium constant climbs, whereas when the methyl group is located at the para position of aniline, oxazine ring stability decreases, the benzoxazine hydrolysis tends to happen and equilibrium constant is significantly low.

Graphical abstract: Influence of substituent on equilibrium of benzoxazine synthesis from Mannich base and formaldehyde

Supplementary files

Article information

Article type
Paper
Submitted
12 May 2014
Accepted
11 Jul 2014
First published
11 Jul 2014

Phys. Chem. Chem. Phys., 2014,16, 18341-18348

Author version available

Influence of substituent on equilibrium of benzoxazine synthesis from Mannich base and formaldehyde

Y. Deng, Q. Zhang, Q. Zhou, C. Zhang, R. Zhu and Y. Gu, Phys. Chem. Chem. Phys., 2014, 16, 18341 DOI: 10.1039/C4CP02053G

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements