Synthesis of a benzoxazine monomer containing maleimide and allyloxy groups

A novel benzoxazine monomer 3-（4-allyloxy）phenyl-3,4-dihydro-2H-6-（N-maleimido）-l,3-benzoxazine （AMB） was synthesized and structure was confirmed by FT-IR, 1H NMR. Thermal analysis （DSC） of AMB showed the introduction of allyloxy group melting point and exhibited a narrow and symmetric curing exothermic window.     

From the study of naturally occurring N-allylated phenazines towards new Pd-mediated transformations

New Pd-mediated reductive heteroannulations of N-allyl diphenylamines accessible through Pd-catalyzed N-arylation and of O-allylethers are reported.     

Novel erythromycin A derivatives: synthesis of 11,12-benzoxazine ketolides

A novel series of 11,12-benzoxazine ketolide derivatives of erythromycin A has been synthesized. The C11,C12-benzoxazine structure was constructed stereoselectively through an intramolecular Michael addition of a C12-O-(2-aminophenyl) group to the enone functionality of the 10,11-anhydro erythromycin A derivative 3.     

Synthesis of 3,4-Dihydro-2H-1,3-benzoxazines by Condensation of 2-Hydroxyaldehydes and Primary Amines: Application to the Synthesis of Hydroxy-Substituted and Deuterium-Labeled Compounds

We report the synthesis of several substituted 3,4-dihydro-2H-1,3-benzoxazines by simple ring closure of 2-hydroxybenzylamines with paraformaldehyde. The facile synthesis of the benzylamine precursors from commercially available salicylaldehyde derivatives affords a powerful general synthetic way to prepare a variety of substituted benzoxazines, avoiding the formation of undesirable oligomeric species, thus leading to a simple workup and improving the yield and purity of the final product. This straightforward method allows synthesis of hydroxy-substituted and deuterium-labeled 1,3-benzoxazines that are not attainable using other synthetic ways.     

3-甲基邻苯二酚/糠胺型聚苯并噁嗪的制备与性能

通过分子设计合成了含有酚羟基的3-甲基邻苯二酚/糠胺型苯并噁嗪(M-f). 通过差示扫描量热法(DSC)测得M-f的放热峰值温度(T_p)为172 ℃, 而间甲酚/糠胺型苯并噁嗪(MC-f)的T_p为244 ℃, 表明酚羟基的引入有利于降低苯并噁嗪的开环固化温度. 通过非等温DSC法研究2种苯并噁嗪单体的固化动力学, Kissinger法和Ozawa法的计算结果均表明M-f的表观活化能低于MC-f. 此外, 通过拉伸剪切强度测试考察了聚苯并噁嗪对于金属基材的黏附性能, M-f聚合物对于铝和低碳钢基材的拉伸剪切强度分别为2.53 MPa和3.09 MPa, 均高于MC-f聚合物.     

Significant enhancement of thermal stability in the non-oxidative thermal degradation of bisphenol-A/aniline based polybenzoxazine aerogel

Previously we reported synthesis of a new type of organic aerogel from phenolic resins called polybenzoxazines and their transformation into carbon aerogels. Here, we further investigate the thermal degradation behaviors of both bulk polybenzoxazines and polybenzoxazine aerogels using Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA)/FTIR, and gas chromatography/time of flight-mass spectroscopy (GC/TOF-MS). The activation energy (E_a) of the decomposition step was determined using the Kissinger method. It was found that the polybenzoxazine aerogels exhibit much higher degradation temperatures and char yields than the bulk. The decomposition temperatures at 10% weight loss and the char yields at 800 °C of the bisphenol-A/aniline based polybenzoxazine aerogel increased up to 24% and 97% higher, respectively, than the corresponding bulk values. Kinetic investigation indicated that the decomposition reaction of bulk polybenzoxazine exhibits three stages, whereas that of the polybenzoxazine aerogel features four stages with much higher overall activation energy. The enhanced thermal stability of the aerogel is ascribed to its highly porous structure, which increases the residence time of the primary decomposition products, and hence generates greater opportunity to form secondary reactions.     

苯并噁嗪酮衍生物对HIV-1逆转录酶抑制活性的QSAR研究极化连续介质模型(PCM)法的应用

采用极化连续介质模型(PCM)法, 计算了19个苯并噁嗪酮衍生物的量子化学参数. 在此基础上, 结合传统理化参数, 建立了相关系数较高(r=0.976)、 标准偏差较小(s=0.111)的回归方程; 采用留一法获得交叉验证的相关系数平方(Q²)为0.914. 对所得到的模型进行了合理的解释, 研究结果对设计更有效的苯并噁嗪酮类抗人类免疫缺陷病毒(HIV)药物具有一定的指导意义.     

Development of an aromatic triamine-based flame-retardant benzoxazine and its high-performance copolybenzoxazines

An aromatic triamine-based flame-retardant benzoxazine (3), which could not be prepared by the traditional approaches, was successfully prepared by a three-step procedure. The first step is the condensation of 2-hydroxybenzaldehyde with an aromatic triamine, forming intermediate (1) with an imine linkage. The second step is the reduction of the imine linkage by sodium borohydride, resulting in intermediate (2) with a secondary amine linkage. The third step is the ring closure condensation of (2), leading to benzoxazine (3). The structures of (1-3) were confirmed by IR, high-resolution mass, ¹H and ³¹P NMR spectra. Benzoxazine (3) was copolymerized with commercial benzoxazines. According to the measurements, thermal properties, flame retardancy, dimensional stability of commercial polybenzoxazines were significantly improved via the incorporation of (3).     

Development of a DOPO-containing benzoxazine and its high-performance flame retardant copolybenzoxazines

A DOPO-containing benzoxazine, which could not be prepared by the traditional approaches, was successfully prepared from phenol, aniline and DOPO by a three-step procedure. The first step is the condensation of 2-hydroxybenzaldehyde with aniline, forming an intermediate imine. The second step is the addition of DOPO to the imine resulting a secondary amine. The third step is the ring closure condensation leading to DOPO-containing benzoxazine. All these structures were confirmed by 1D and 2D NMR spectra. The curing of mixtures of DOPO-containing benzoxazine and benzoxazine of bisphenol A has been studied. In the samples the molar ratio of benzoxazine monomers was varied to achieve different phosphorus content. The phosphorus-containing polybenzoxazines have been characterized by dynamic mechanical thermal analysis and thermogravimetric analysis. Limiting oxygen index values indicates good flame retardant properties.     

Facile Mechanochemical Preparation of Polyamide-derivatives via Solid-state Benzoxazine-isocyanide Chemistry

With the exploration of novel sustainable protocol for functional polyamides'(PAs) construction as the starting point, herein, the small molecular model compound(M1-ssBIC) was prepared firstly by manual grinding of monofunctional benzoxazine(1 a) and isocyanide(1 b) via solid-state benzoxazine-isocyanide chemistry(ssBIC) to evaluate the feasibility of ssBIC. Linear PAs(P1-series polymers) were subsequently synthesized from biunctional benzoxazine(2 a) and isocyanide(2 b), and the influence of the loading of catalyst(octylphosphonic acid)(OPA) on the polymerization was investigated. Afterwards, two kinds of cross-linked PAs were successfully constructed via ssBIC by using trifunctional benzoxazine(3 a) and cross-linked polybenzoxazine(4 a) as reaction substrates, respectively, thus verifying the adaptability of ssBIC. Structural characterization indicates that amide, phenolic hydroxyl and tertiary amine substructures, with metal-complexing capability, have been successfully integrated into the obtained PAs. A type of representative PA/silver composite(P3-AgNPs) was prepared subsequently via in situ reduction treatment, and its application as recyclable reduction catalyst for organic pollutant p-nitrophenol(4-NP) was preliminarily investigated here to provide the example for possible downstream application of ssBIC. We think that this current work could provide a new pathway for the construction of functional PAs through facile and sustainable ssBIC protocol.