Effect and regeneration of heterogeneous palladium/charcoal catalysts poisoned by tetramethylthiourea-quinoline in the stereoselective hydrogenation of methacycline to α-doxycycline
Effect and regeneration of heterogeneous palladium/charcoal catalysts poisoned by tetramethylthiourea-quinoline in the stereoselective hydrogenation of methacycline to α-doxycycline
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DOI：
10.1016/s0926-860x(03)00471-x
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发表时间：
2003-10-15
影响因子：
5.5
通讯作者：
Sha, YW
中科院分区：
文献类型：
--
作者：
Pan, ZZ;Sha, YW
对于通过甲环素氢化合成临床上重要的α-多西环素，控制一些参数以进行优化：（a）0.4wt.%的用量，结果表明，在最佳反应条件下，催化剂的立体选择性和转化率分别为94.5%和90.7%，反应温度和反应时间对催化剂的催化活性有显著影响。使用后，催化剂的转化活性和立体选择性都大大降低。与新鲜值相比，剩余的总孔体积仅为1.48%，剩余的总BET表面积仅为0.52%。考察了几种短链脂肪醇对催化剂的再生作用，并通过甲醇脱水处理，获得了成功的结果。经4次再生后，转化率和立体选择性仅分别下降4%和1%。(C)2003 Elsevier B. V.保留所有权利。
For the synthesis of clinically important alpha-doxycycline by hydrogenation of methacycline, some parameters were controlled for optimization: (a) the dosage of 0.4 wt.% Pd/C catalyst poisoned by tetramethylthiourea-quinoline (TQ), which has the lowest Pd content till now; (b) the reaction temperature and reaction time; (c) the effect of TQ Under optimized conditions, the best stereoselectivity (94.5%) and excellent conversion (90.7%) were obtained. After being employed, the catalyst showed great reduction in conversion activity and stereoselectivity. Compared to fresh values, the total pore volume that remained was only 1.48% and the total BET surface area that remained was only 0.52%. Some short-chain aliphatic alcohol has been examined for the catalyst regeneration, and successful results were obtained by methanol refluxing treatment. After four times regeneration, the conversion and stereoselectivity only decreased 4 and 1%, respectively. (C) 2003 Elsevier B.V. All rights reserved.