硫酸氢钠催化合成柠檬酸三丁酯

以柠檬酸、正丁醇为原料，硫酸氢钠为催化剂，催化合成柠檬酸三丁酯．考察了影响产率的多种因素．确定了最佳反应条件．     

Enzyme activity and myoglobin concentration in rat myocardium and skeletal muscles after passive intermittent simulated altitude exposure

Abstract

We studied the effect of intermittent hypobaric hypoxia exposure on lactate dehydrogenase and citrate synthase activities, together with myoglobin content, of rat myocardium, tibialis anterior, and diaphragm muscles. The intermittent hypoxia exposure programme consisted of daily 4-h sessions in a hypobaric chamber (5000 m) over a period of 22 days. Samples were taken at the end of the programme, and 20 and 40 days later, and compared with those of control animals. In myocardium, lactate dehydrogenase activity was significantly depressed in animals 20 days post-exposure (314.6 ± 15.3 IU · g^?1) compared with control animals (400 ± 14.3 IU · g^?1), while citrate synthase activity and myoglobin concentration showed a significant stepwise increase from control animals (88.2 ± 3.6 IU · g^?1 and 4.38 ± 0.13 μm · mg^?1) to animals 20 days (104.7 ± 3.7 IU · g^?1 and 5.01 ± 0.17 μm · mg^?1) and 40 days post-exposure (108.8 ± 6.5 IU · g^?1 and 5.11 ± 0.22 μm · mg^?1). In contrast, no differences were found in diaphragm and tibialis anterior muscles. Our results show that intermittent hypobaric hypoxia exposure increased the oxidative character of myocardium even 20 days after the hypoxic stimulus has ceased, and that this effect lasts for more than 40 days for citrate synthase activity and myoglobin concentration. These findings support our previous results on skeletal and cardiac muscle capillarization after passive intermittent simulated altitude exposure, thus providing morphofunctional and biochemical evidence for increased cardiac aerobic efficiency.     

正交试验法合成柠檬酸三丁酯

采用柠檬酸和正丁醇为原料合成柠檬酸三丁酯。通过正交试验考察了催化剂种类、醇酸摩尔比、反应时间及反应温度对酯化率的影响,从而确定了最佳合成工艺条件为:采用一水合硫酸氢钠为催化剂,醇酸摩尔比为4:1,反应时间为2.5h,反应温度为115℃,柠檬酸三丁酯的酯化率可达96.94%。     

聚氯乙烯塑料中四类增塑剂的同时无损测定

为了在线监控聚氯乙烯塑料中增塑剂的含量,采用傅立叶变换红外光谱-ATR技术进行光谱测定,利用偏最小二乘法对所测的谱图进行分析,建立了聚氯乙烯塑料中四种不同类型的增塑剂的无损定量测定方法,同时测定了聚氯乙烯塑料中邻苯二甲酸酯类增塑剂、己二酸酯类增塑剂、柠檬酸酯类增塑剂和磷酸酯类增塑剂。该方法不受基体干扰,结果可靠,简单快速,适合于流水线的质量控制。     

柠檬酸铜配合法测定柠檬酸含量

根据铜离子与柠檬酸钠形成稳定配合物的原理，用甲基红作指示剂、氢氧化钠作滴定剂的酸碱滴定法测定了柠檬酸的含量。     

Nitrate Removal from Drinking Water with Sodium Citrate as Sole Carbon Source

Nitrateremovalfromdrinkingwaterisoneofthemainproblemsinwaterresearch. Severalnitrateremovalmethodssuchasionexchange, reverseosmosis, electrodialysis, distillation, chemicalreductionandbio denitrificationhavebeenemployedwithdifferentratesofefficiency[1, 2]. Bio denitrificationhasbeenprovedtobeoneofthemostfeasible, advanced,selectiveandcosteffectiveprocessesforremovingnitratebydissimilationreduction[3], whichtransformsnitrateintonitrogengas[4]. Thisprocesshasbeenappliedtonitrogenremovalofwas…     

阳离子交换树脂负载金属离子催化合成柠檬酸三辛酯的研究

以柠檬酸和正辛醇为原料,采用强酸性阳离子交换树脂负载改性制备酯化催化剂,合成柠檬酸三辛酯.考察影响酯化反应的因素,结果表明:在190℃,酸醇摩尔比为1:4,催化荆用量2.0g,反应1.5h后,酯化率可达96.4%,该催化剂的催化活性较高,便于与产物分离,可以重复使用.     

杂多酸HPW12催化合成柠檬酸三正丁酯的研究

柠檬酸三正丁酯简称TBC,分子式为C18H32O7,该产品量种良好的无毒增塑剂,广泛用于聚乙烯、聚氯乙烯、聚丙烯和多种纤维素树脂的增塑,以及食品包装材料和医疗用具的增塑剂。采用HPW12杂多酸为催化剂合成TBC,取得了良好结果。     

WO3／MOO3／SiO2催化合成柠檬酸三丁酯

用正丁醇和柠檬酸为原料,WO3／MOO3／SiO2为催化剂催化合成柠檬酸三丁酯。通过考察醇与酸的物质的量比,反应温度和反应时间,催化剂用量和溶剂用量对酯化反应的影响。确定合成柠檬酸三丁酯的最佳反应条件为n（正丁醇）／n（柠檬酸）=4．5,催化剂用量为反应物柠檬酸质量的6％,反应温度130—140℃,反应时间3．5h,酯化率最高达98．5％,产率最高迭94．3％。WO3／MOO3／SiO2催化剂可重复使用,其催化活性基本不变。实验对合成的产品进行了红外光谱分析及折光率的测定,与文献值相符。