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首页> 外文期刊>Journal of Chemical Technology & Biotechnology >Insight into microwave irradiation and enzyme catalysis in enantioselective resolution of RS-(+/-)-methyl mandelate
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Insight into microwave irradiation and enzyme catalysis in enantioselective resolution of RS-(+/-)-methyl mandelate

机译：RS-（+/-）-扁桃酸甲酯对映选择性拆分中微波辐射和酶催化的见解

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BACKGROUND: Mandelic acid enantiomers are important chiral analogs used for the resolution of racemic alcohols and amines. R-(-)-mandelic acid is a precursor for the production of semi-synthetic penicillins and cephalosporins and also for the synthesis of various pharmaceuticals. Production of optically pure mandelic acid enantiomers is commercially significant. This work deals with the resolution of RS-(+/-)-methyl mandelate to produce optically pure R-(-)-mandelic acid in non-aqueous media via lipase-catalyzed hydrolysis under microwave irradiation. RESULTS: Among three commercial lipases, Novozym. 435 (Candida antartica B immobilized on macroporous polyacrylate resin) was found to be the most effective in the selective hydrolysis of R-(-)-methyl mandelate to R-(-)-mandelic acid from the racemic mixture of RS-(+/-)-methyl mandelate, with an optical purity (ee(p)) of 84.2% after 4 h at 50 degrees C. The effects of various parameters were studied to arrive at the optimum parameters and kinetics. The optimum catalyst loading was found to be 5 mg cm(-3) at a concentration of 0.25 mmol cm-3 each of methyl mandelate and water. Based on the initial rate studies and concentration profiles, a complete rate equation is proposed, which includes the irreversible inactivation caused by RS-(+/-)-methyl mandelate, and it follows the ternary complex mechanism with dead end inhibition by RS-(+/-)-methyl mandelate. CONCLUSION: Novozym 435 is the most active lipase for resolution of R-(-)-mandelic acid from RS- (+/-)-methyl mandelate in tert-butanol. Various equilibrium constants were evaluated and simulations were performed giving excellent agreement between the two. (C) 2008 Society of Chemical Industry.
机译：背景：扁桃酸对映体是重要的手性类似物，用于拆分外消旋醇和胺。 R-（-）-扁桃酸是生产半合成青霉素和头孢菌素的前体，也是合成各种药物的前体。光学纯扁桃酸对映体的生产在商业上是重要的。这项工作涉及解决RS-（+/-）-扁桃酸甲酯在微波辐射下通过脂肪酶催化水解在非水介质中产生光学纯的R-（-）-扁桃酸的分辨率。结果：在三种商业脂肪酶中，诺维辛。发现435（固定在大孔聚丙烯酸酯树脂上的南美大虫B）在将R-（-）-扁桃酸甲酯从RS-（+ /的外消旋混合物）选择性水解为R-（-）-扁桃酸中最有效。 -）-扁桃酸甲酯，在50摄氏度下4小时后的光学纯度（ee（p））为84.2％。研究了各种参数的影响，以获得最佳参数和动力学。发现扁桃酸甲酯和水各自的浓度为0.25 mmol cm-3时，最佳催化剂负载量为5 mg cm（-3）。基于初始速率研究和浓度分布图，提出了一个完整的速率方程，其中包括由RS-（+/-）-扁桃酸甲酯引起的不可逆失活，并遵循具有RS-（-）抑制死角的三元复合机理。 +/-）-扁桃酸甲酯。结论：Novozym 435是从叔丁醇中的RS-（+/-）-扁桃酸甲酯拆分R-（-）-扁桃酸的活性最高的脂肪酶。评估了各种平衡常数，并进行了仿真，从而使两者之间具有极好的一致性。 （C）2008年化学工业协会。

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