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对对羟基苯甲酸酯、对羟基苯甲酸酯钠盐、三氯生几种防腐剂在牙膏中的抑菌效果进行研究,结果表明,由于对羟基苯甲酸酯钠盐良好的水溶性,能够在牙膏中发挥更好的防腐效果。 相似文献
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对羟基苯甲酸酯的催化剂研究 总被引:3,自引:0,他引:3
综述了固体超强酸TiO2/SO42-,磷钨、硅钨杂多酸及固载杂多酸盐TiSiW12O40/TiO2,浓硫酸(微波常压法),Lewis酸(FeCl3·6H2O,Fe2(SO4)3·xH2O)等几种不同催化剂催化合成对羟基苯甲酸酯的实验结果.分析各种固体催化剂对该酯化反应的催化活性、选择性、重复使用性能及使用范围. 相似文献
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对-羟基苯甲酸苄酯合成方法的改进 总被引:7,自引:0,他引:7
用对 羟基苯甲酸和氯化苄为原料 ,以二甲基亚砜 (DMSO)为溶剂 ,采用改进工艺合成对 羟基苯甲酸苄酯。结果表明 ,n(酸 )∶n(氯化苄 ) =1 0 0∶1 6 0 ,反应温度 134℃ ,反应时间 3 5h ,产率达 96 4 % ,产品质量分数 99% 相似文献
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十六醇磷酸酯合成工艺研究 总被引:1,自引:0,他引:1
研究了十六醇磷酸酯的合成工艺,采用加水反应和水解工艺制取单烷基磷酸酯,考察了十六醇与五氧化二磷(P2O5)的摩尔比、反应时间、反应温度、水解等因素对转化率和单烷基磷酸酯质量分数的影响。得到的优化工艺条件为:酯化反应阶段,十六醇、P2O5及水的摩尔比为1.70∶1.00∶1.13,85℃下反应10 h;水解反应阶段,加水量为磷酸酯质量的4%,85℃,水解2 h。结果表明,所得的十六醇磷酸酯白度较好,产物单酯的质量分数>78%、酯化率>85%、单酯率>90%。 相似文献
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Molecular imprinting polymers (MIPs) for salicylic acid (SA), 3‐hydroxybenzoic acid (3HBA), and 4‐hydroxybenzoic acid (4HBA) were synthesized using styrene and 4‐vinylpyridine (4‐VPy) as functional monomer and divinylbenzene (DVB) as crosslinker. The adsorption characteristics of hydroxybenzoic acid (HBA) isomers on each MIP were investigated. The materials used for the polymerization of each 3HBA and 4HBA‐MIPs were adsorbed relatively well. This verifies that the MIPs that can adsorb template selectively were synthesized. However, SA‐MIP had no molecular imprinting effect. SA has intramolecular hydrogen bond and it is difficult to adsorb on recognition site of SA‐MIP, because its structure differs from that of recognition site of SA‐MIP. It indicates that SA‐MIP had no recognition effect. 1,2,3,4‐Tetrahydro‐1‐naphthol (THN)‐MIP was synthesized, which is similar to SA with intramolecular hydrogen bond. SA was separated selectively using THN‐MIP. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
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以对叔丁基苯甲酸、无水甲醇为原料,对甲苯磺酸为催化剂,合成对叔丁基苯甲酸甲酯,应用正交设计探讨了催化酯化的影响因素。结果表明,最佳工艺条件为:醇酸摩尔比为6∶1,催化剂用量占物质总质量的13.3%,反应时间为6 h,反应温度是65℃,环己烷用量占液体总体积的37.5%,酯化率达97%,产品结构经沸点、折光率和IR确证。 相似文献
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脂肪酸甲酯乙氧基化物中未反应脂肪酸甲酯的测定 总被引:1,自引:0,他引:1
采用气相色谱法(GC)测定了不同脂肪酸甲酯乙氧基化物(MEE)中未反应的脂肪酸甲酯的质量分数。以十三酸甲酯为内标,对不同MEE进行了定性和定量分析,同时以十二酸甲酯为标准考察了回收率。实验结果表明:该法相对标准偏差在1.2%以内,回收率大于96%。由测定结果可知:GC法简便、快速、准确率高、重现性好、能准确测定不同MEE中未反应脂肪酸甲酯的质量分数,可作为MEE产品质量监控的方法,也可为MEE新产品、新配方研究与开发提供有效的参考依据。 相似文献
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A series of thermotropic copolyesters were synthesized by direct thermal melt polycondensation of p‐acetoxybenzoic acid (PHB) with trans‐p‐acetoxycinnamic acid (PHC). The dynamic thermogravimetric kinetics of the copolyesters in nitrogen were analyzed by four single heating‐rate techniques and three multiple heating‐rate techniques. The effects of the heating rate, copolyester composition, degradation stage, and the calculating techniques on the thermostability and degradation kinetic parameters of the copolyesters are systematically discussed. The four single heating‐rate techniques used in this work include Friedman, Freeman–Carroll, Chang, and the second Kissinger techniques, whereas the three multiple heating‐rate techniques are the first Kissinger, Kim–Park, and Flynn–Wall techniques. The decomposition temperature of the copolyesters increases monotonically with increasing PHB content from 40 to 60 mol %, whereas their activation energy exhibits a maximal value at the PHB content of 50 mol %. The decomposition temperature, activation energy, the order, and the frequency factor of the degradation reaction for the thermotropic copolyester with PHB/PHC feed ratio of 50/50 mol % were determined to be 374°C, 408 kJ/mol, 7.2, and 1.25 × 1029 min?1, respectively. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 445–454, 2004 相似文献