共查询到19条相似文献,搜索用时 93 毫秒
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以乙二醛、甲基肼和盐酸羟胺为起始原料,经缩合、肟化得到中间体肟基甲腙;该中间体不经分离直接加入到硫酸铜-吡啶-水体系中,经缩合环化得到2-甲基三唑-1-氧化物(MTO);随后用混酸(硝酸+硫酸)硝化得到目标产物2-甲基-4,5-二硝基三唑-1-氧化物(DNMTO);初步探讨了环化反应的机理,研究了反应温度与时间等因素对硝化反应的影响,确定了最佳硝化反应条件.与此同时,利用红外光谱、核磁共振、质谱及元素分析等分析了中间产物和DNMTO的组成和结构.结果表明,目标产物的总收率为16%,纯度为99%;最佳硝化反应温度为100℃,最佳硝化反应时间为0.5h. 相似文献
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An effective process for the purification of folic acid candidate reference material with preparative high-performance liquid chromatography (Pre-HPLC) was developed in this study. During the process of experimental operation, parameters including the influences of mobile phase, flow rate, and injection volume on the purity and yield were investigated, and the optimized conditions were as follows: the mobile phase was acetonitrile and water in a gradient mode with flow rate of 16?mL/min and injection volume of 2.0?mL at concentration of 10?mg/mL. Under the conditions, the purity and yield of folic acid product were up to 99.4% and 21.0%, respectively, whereas the purity of folic acid raw material was 95.2%. The purified folic acid product was characterized by LC–MS, HPLC, Karl Fischer coulometer, and quantitative nuclear magnetic resonance (qNMR). Results proved that the main component of the product was folic acid and the purities determined by HPLC and qNMR were consistent. Two impurities including N-(4-aminobenzoyl)-L-glutamic acid and pteroic acid were further quantified by LC–MS. Compared with the recrystallization approach, the purity of folic acid obtained by Pre-HPLC increased from 98.2% to 99.4%. 相似文献
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用自制的(S,S)-Salen Co(Ⅲ)OAc催化剂水解动力学拆分外消旋环氧氯丙烷得到高光学纯的(S)-3-氯-1,2-丙二醇和较高光学纯的(R)-环氧氯丙烷。 以(S)-3氯-1,2-丙二醇为手性原料和4-(2-甲氧基乙基)苯酚缩合,再与氯化亚砜反应得环状亚硫酸酯,最后和异丙胺反应得(S)-美托洛尔,光学纯度大于99%。 另外以(R)-环氧氯丙烷为手性原料和4-(2-甲氧基乙基)苯酚反应,再与异丙胺作用得到(S)-美托洛尔,光学纯度大于92%。 (S)-美托洛尔的总收率为53.9%,结构经IR、1H NMR、13C NMR和MS测试技术确证。 该路线原料利用率高,拆分后的2种产物均能用于目标化合物的合成。 相似文献
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A pressure-swing adsorption (PSA) simulation study was performed for the separation of a mixture of 95% O2 and 5% Ar using a molecular sieve carbon (MSC) as the adsorbent. Two PSA cycles have been outlined to maximize the recovery of either argon or oxygen as a high purity product. The effect of cycle parameters such as cocurrent depressurization pressure, purge/feed ratio, pressure ratio and adsorption pressure on the separation of O2/Ar has been studied. It was found that it is feasible to obtain an argon product of purity in excess of 80% with reasonably high recovery using one of the cycles. The other cycle is capable of producing high purity oxygen (>99%) at high recovery (>50%) with reasonably high product throughputs. The PSA process can be conducted at room temperature and hence has an advantage over conventional processes like cryogenic distillation and cryogenic adsorption. 相似文献
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Nguyen Van Duc Long Thai‐Hoang Le Jin‐Il Kim Ju Weon Lee Yoon‐Mo Koo 《Journal of separation science》2009,32(11):1987-1995
Simulated moving bed (SMB) processes have been widely used in the sugar industries with ion‐exchange resin as a stationary phase. D ‐Psicose, a rare monosaccharide known as a valuable pharmaceutical substrate, was synthesized by the enzymatic conversion from D ‐fructose. The SMB process was adopted to separate D ‐psicose from D ‐fructose. Before the SMB experiment, the reaction mixture including D ‐psicose and D ‐fructose was treated by a deashing process to remove contaminants, such as buffers, proteins, and other organic materials. Four columns packed with Dowex 50WX4‐Ca2+ (200–400 mesh) ion‐exchange resins were used in the four‐zone SMB. Single‐step frontal analysis was performed to estimate the isotherm parameters of each monosaccharide. The operating conditions of the SMB process were determined based on the Equilibrium Theory. According to the simulation of the SMB process, the purity and yield of extract product (D ‐psicose) achieved were 99.04 and 97.46%, respectively and those of raffinate product (D ‐fructose) were 99.06 and 99.53%, respectively. Under the optimized operating condition, complete separation (extract purity = 99.36%, raffinate purity = 99.67%) was achieved experimentally. 相似文献
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S. P. Patil D. B. Kalgutkar N. Jaychandran V. K. P. Unny 《Journal of Radioanalytical and Nuclear Chemistry》2005,267(1):49-51
Summary An improved method for the preparation of [14C]thiourea of high radiochemical purity is described. [14C]thiourea is prepared by the barium cyanamide route and is purified by vacuum-sublimation. The labeled product showed ammonium
[14C]thiocyanate as a radiochemical impurity in the range of 2-4%. This was further purified by silica-gel column chromatography
to get the product having more than 99% radiochemical purity. 相似文献
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制备型高效液相色谱法分离纯化川西獐牙菜提取物中的龙胆苦苷 总被引:1,自引:0,他引:1
龙胆苦苷(GPS)是龙胆类药材及其相关制品质量控制的指标成分。本研究利用制备型高效液相色谱从川西獐牙菜提取物中分离纯化龙胆苦苷对照品。对制备色谱的流动相组成、流速、进样量和检测波长等制备参数进行了优化。采用的色谱柱为C18柱(200 mm×50 mm, 5 μm),流动相为甲醇和0.1%乙酸水溶液(体积比为30:70),流速为75 mL/min,检测波长为254 nm,进样体积为500 μL。在30 min的运行时间内,龙胆苦苷与其他干扰成分得到了很好的分离,产品纯度达到了99%以上。此方法具有快速高效、产品纯度高的特点,可用于制备龙胆苦苷对照品和对龙胆苦苷制品的质量控制。 相似文献