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511.
Sheng-Huei Hsiao Chin-Ping Yang Sheng-Wen Wang Ming-Hung Chuang 《Journal of polymer science. Part A, Polymer chemistry》1999,37(18):3575-3583
1,1-Bis[4-(4-carboxyphenoxy)phenyl]cyclohexane (III) and 1,1-bis[4-(4-aminophenoxy)phenyl]cyclohexane (V) were prepared in two main steps starting from the aromatic nucleophilic substitution of p-fluorobenzonitrile and p-chloronitrobenzene, respectively, with 1,1-bis(4-hydroxyphenyl)cyclohexane in the presence of potassium carbonate in N,N-dimethylformamide (DMF). Using triphenyl phosphite and pyridine as condensing agents, two series of polyamides with cyclohexylidene cardo groups were directly polycondensated from dicarboxylic acid III with various aromatic diamines or from diamine V with various aromatic dicarboxylic acids in an N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The polyamides exhibited inherent viscosities in the range of 0.45 to 1.78 dL/g. Almost all of the polymers were readily soluble in polar aprotic solvents such as NMP and N,N-dimethylacetamide (DMAc) and could afford transparent, flexible, and tough films by solution casting. The glass transition temperatures (Tg) of these aromatic polyamides were in the range of 180–243°C by DSC, and the 10% weight loss temperatures in nitrogen and air were all above 450°C. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3575–3583, 1999 相似文献
512.
B. Jacques J. Devaux R. Legras E. Nield 《Journal of polymer science. Part A, Polymer chemistry》1996,34(7):1189-1194
The occurrence of ester-interchange reactions during PET/PBT blend processing has been confirmed by 13C-NMR measurements. The limitations of the method for precise quantification of the extent of reaction between high molecular weight polyester blends have also been pointed out. Titanium alkoxide has been confirmed as an efficient catalyst, and, within experimental precision, the stabilizing effect of triphenyl phosphite addition has been demonstrated. © 1996 John Wiley & Sons, Inc. 相似文献
513.
Sheng-Huei Hsiao Perng-Chih Huang 《Journal of polymer science. Part A, Polymer chemistry》1997,35(12):2421-2429
Two ether-sulfone-dicarboxylic acids, 4,4′-[sulfonylbis(2,6-dimethyl-1,4-phenylene)dioxy]dibenzoic acid (Me- III ) and 4,4′-[sulfonylbis(1,4-phenylene)dioxy]-dibenzoic acid ( III ), were prepared by the fluorodisplacement of 4,4′-sulfonylbis(2,6-dimethylphenol) and 4,4′-sulfonyldiphenol with p-fluorobenzonitrile, and subsequent alkaline hydrolysis of intermediate dinitriles. Using triphenyl phosphite (TPP) and pyridine as condensing agents, aromatic polyamides containing ether and sulfone links were prepared by the direct polycondensation of the dicarboxylic acids with various aromatic diamines in the N-methyl-2-pyrrolidone (NMP) solution containing dissolved calcium chloride. The inherent viscosities of the resulting polymers were above 0.4 dL/g and up to 1.01 dL/g. Most of the polyamides were readily soluble in polar solvents such as NMP, N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), and afforded tough and transparent films by solution-casting. Most of the polymers showed distinct glass transition on their differential scanning calorimetry (DSC) curves, and their glass transition temperatures (Tg) were recorded between 212–272°C. The methyl-substituted polyamides showed slightly higher Tgs than the corresponding unsubstituted ones. The results of the thermogravimetry analysis (TGA) revealed that all the polyamides showed no significant weight loss before 400°C, and the methyl-substituted polymers showed lower initial decomposition temperatures than the unsubstituted ones. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2421–2429, 1997 相似文献
514.
1,3-Bis(4-bromobutyl)-6-methyluracil reacts with diethyl 2-(dimethylamino)ethylphosphonate to form a bisquaternary ammonium
salt, whereas the reaction of 1,3-bis-(6-bromohexyl)-6-methyluracil with diethyl 2-(diethylamino)ethyl phosphate gives 1,3-bis-[(6-diethoxyphosphoryloxy)hexyl]-6-methyluracil
and 1,1,4,4-tetraethylpiperazinium dibromide.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1130–1132, June, 2000. 相似文献
515.
Re/Sibunite is a more active and selective catalyst for hydrogenation of ethyl acetate to ethanol under elevated temperatures
and hydrogen pressures than Re/θ-Al2O3 and Re/γ-Al2O3. The activity of the catalyst is increased on replacing NH4ReO4 with HReO4 and treatment of the support with a 13% solution of HNO3.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1006–1008, May, 1999. 相似文献
516.
517.
亚磷酸二正丙酯的气相色谱法测定 总被引:5,自引:1,他引:4
采用气相色谱法分离和测定合成有机磷农药的中间体亚磷酸二正丙酯。试验结果表明,在 5% OV- 7/Chromosorb W- AW DMCS( 0.231~ 0.387 mm)的色谱柱上,亚磷酸二正丙酯与内标物联苯等之间具有较好的分离效果。并且,以联苯为内标物时,亚磷酸二正丙酯的质量校正因子相当稳定,fW. A=2.47± 0.09(α =0.05,n=5)。该法操作简便、快速,准确度和精密度较好,对同一试样的 5次平行独立测定的相对标准偏差( RSD)为 1.57%;该法的标准加入回收率达 99.2%~ 101.9%。 相似文献
518.
具有新颖结构的亚磷酸锌化合物的水热合成与表征 总被引:2,自引:2,他引:0
在水热体系中以二乙烯三胺为模板剂合成了结构新颖的亚磷酸锌化合物Zn(DETA)Zn2(HPO3)3.单晶X射线衍射分析结果表明,该化合物属正交晶系,Cmca空间群,晶胞参数a=1.889 25(1)nm,b=1.001 04(5)nm,c=1.630 32(8)nm,β=90°,V=3.083 3(3)nm3,Z=4,DC=1.162 Mg.m-3,最终因子R1[I>2σ(I)]=0.068 5,wR2[I>2σ(I)]=0.160 5.该化合物的结构中含有{ZnO4},{ZnO2N3}和{HPO3}基本结构单元,其中{ZnO4}和{HPO3}通过桥氧原子共顶点相互交替连接形成具有4-,8-和12-元环的无限延伸的二维层.有趣的是,{ZnO2N3}结构单元以二聚体形式{ZnODETA}2悬挂在12-元环孔道中,这种结构在亚磷酸锌中鲜有报道. 相似文献
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520.