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Bisbenzoxazine–Bismaleimide Blends: Thermal Studies
Published in Didier Rouxel, Sabu Thomas, Nandakumar Kalarikkal, Sajith T. Abdulrahman, Advanced Polymeric Materials, 2022
S. Shamim Rishwana, M. M. Thahajjathul Kamila, C. T. Vijayakumar
Aromatic oxazines were first synthesized in 1944 by Holly and Cope [6] through Mannich reaction from phenols, formaldehyde and amines. They first proposed the 3,4-dihydro-2H-1,3-benzoxazine structure from the condensation of formaldehyde with o-hydroxybenzylamine. From the1950s to the 1960s, Burke et al. synthesized many benzoxazines and naphthoxazines [7] for the purpose of antitumor activity test. Reiss et al. investigated the polymerization of monofunctional benzoxazines with and without phenol as an initiator, resulting in linear polymers under 4000 molecular weight [8].
Synthesis, crystal structure and catalytic activity of an oxo-diperoxo tungsten(VI) complex containing an oxazine ligand for selective oxidation of sulfides
Published in Journal of Coordination Chemistry, 2018
Mojtaba Bagherzadeh, Parvin Esmailpour, Alireza Abbasi, Ali Akbari, Mojtaba Amini
The structure of the complex has been confirmed by X-ray crystallography. This complex crystallized from DMF by slow diffusion of ether as the solvent adduct [WO(O2)2(Hphox)(DMF)] in the space group P-1 (triclinic). The crystallographic data of [WO(O2)2(Hphox)(DMF)] are summarized in Table 1 and an ORTEP view is shown in Figure 1. Bond lengths and angles are given in Table 2. The coordination geometry around the tungsten center is distorted pentagonal bipyramidal with two peroxo groups, one oxo ligand, one oxazine and one DMF molecule. Therefore, the oxazine ligand Hphox coordinates to the tungsten ion only via the phenolic oxygen and the nitrogen atom of the imine group remains uncoordinated. The oxo donor and DMF ligand are in axial positions and two peroxo groups and oxazine ligand are in equatorial positions. According to the previously reported study [25], incorporation of two peroxo groups on the equatorial plane results in enhanced stability of complex.
Studies on the mesophase formation mechanism of polybenzoxazines: polymerisation induction
Published in Liquid Crystals, 2020
Ying Liu, Xiaoshan Zhen, Sheng Gao, Qingbin Xue, Zaijun Lu
Figure 1(a) shows the 1H NMR spectrum of PC-AC monomer. The resonance signals at 4.65 and 5.37 ppm are, respectively, attributed to the methylene protons of Ar–CH2–N and O–CH2–N in the oxazine ring, indicating the formation of benzoxazine rings. The resonance signals at 4.82 and 5.41 ppm belong to the methine proton adjacent to oxygen atom and the olefin proton in cholesteryl group, respectively. The integrated intensity ratio of those four resonance signals is 2.00:1.96:1.10:1.08, which is very close to the theoretical value of 2.00:2.00:1.00:1.00. In addition, the resonance signal at 2.26 ppm is assigned to the methyl proton of p-cresol.