2109 Korean J. Chem. Eng., 31(12), 2109-2123 (2014) DOI: 10.1007/s11814-014-0284-z REVIEW PAPER pISSN: 0256-1115 eISSN: 1975-7220 INVITED REVIEW PAPER † To whom correspondence should be addressed. E-mail: ingolepravin@gmail.com Copyright by The Korean Institute of Chemical Engineers. Methods for separation of organic and pharmaceutical compounds by different polymer materials Pravin Ganeshrao Ingole* ,† and Neha Pravin Ingole** *Korea Institute of Energy Research, 71-2, Jang-dong, Yuseong-gu, Daejeon 305-343, Korea **Department of Biology, Chungnam National University, Daejeon 305-764, Korea (Received 27 May 2014 • accepted 23 September 2014) Abstract -The discrimination of enantiomers is a challenging task in separation technology, and using a membrane is most promising for separating enantiomers from racemic mixture. The optical resolution of chiral compounds is of interest to researchers working in a variety of fields from analytical, organic and medicinal chemistry, to pharmaceu- tics and materials, to process engineering for fabricating pharmaceuticals, agrochemicals, fragrances and foods, and so on. There is considerable demand for separation techniques appropriate for the large-scale resolution of chiral molecules. The separation of chiral compounds using chiral or achiral/non-chiral polymeric membranes with or without chiral selector represents a promising system for future commercial applications. This review focuses on an active field of chiral separation, membrane-based enantioseparation technique, which has potential for large-scale production of single- enantiomers. Enantiomeric separation by membrane processes has been studied using various configurations of liquid and solid polymer membranes. Selectivity and permeability of liquid-membranes is reasonably good because the rate of diffusion of solute molecules is high in liquids but has inferior durability and stability. Solid polymer membranes have inferior permeability because diffusion of solute through solids is slow but quite stable and durable; however, commercial application of membrane technology for optical resolution is yet to be realized. Several chiral separation membranes were prepared from chiral polymers where enantioselectivity was generated from chiral carbons in the main chain. However, it is rather tricky to generate excellent chiral separation membranes from chiral polymers alone, because racemic penetrants mainly encounter the flexible side chains of the membrane polymers. Keywords: Chiral Separation, Optical Resolution, Enantioselective Polymeric Membranes, Pharmaceutical INTRODUCTION Many pharmaceutical, drug and flavor compounds are racemic mixtures. However, it is well known that only one of the two enanti- omers performs the required biological action or what we called practical action. The surplus one, which means an impurity, may cause unwanted side effects. Therefore, chiral resolution becomes a very important separation process, particularly in the field of medi- cine and agriculture chemicals [1,2]. Enantiomers of a molecule have identical physical properties such as melting point and vapor pressure with one exception: they scatter polarized light differently [3]. For example, if linearly polarized light passes through a solu- tion of chiral molecules (all of the same enantiomer), the plane of polarization will rotate. Most importantly, the two enantiomers of a molecule will rotate the plane of polarization in opposite directions. This phenomenon is called optical rotation and the compounds pos- sessing this property are called as optically active. Enantiomers are most commonly formed when a carbon atom contains four differ- ent groups or atoms. Chirality plays an important role in human life. The best exam- ple of chiral influence is given by nature itself. Most recognition systems in nature (e.g., enzymes, receptors) [4-11] distinguish pairs of enantiomers. The majority of biologically active molecules, includ- ing naturally occurring amino acids and sugars, are chiral [12,13]. Enantiomers of a drug have similar physicochemical properties but differ in their biological properties [14,15]. The distribution, metab- olism and excretion in the body usually favor one enantiomer over the other because enantiomers stereo-selectively react in biological systems. Enantioselective HPLC-DAD method is used for the deter- mination of etodolac enantiomers in tablets, human plasma and appli- cation to comparative pharmacokinetic study of both enantiomers after a single oral dose to twelve healthy volunteers [16]. Further- more, biological transformation of drugs can be stereoselective, so the enantiomeric composition of chiral compounds may be changed. Additionally, due to different pharmacological activity, chiral drugs can differ in toxicity [17]. Thalidomide is an excellent example, due to the administration of the racemic thalidomide to pregnant women during 1960’s thousands of babies were born with physical defor- mities. (+)-enantiomer of thalidomide is harmless (has tranquilizing properties) but (-)-enantiomer is teratogenic and leads to malfor- mations of embryos if administered to pregnant woman. Unfortu- nately, many chiral drugs are still produced as racemate because either their chiral separation is difficult, or the cost of their stereose- lective synthesis is too high, or simply at the time of the discovery of the drug, only racemic mixture was considered in the animal; and the clinical pharmacology, toxicology and teratology studies and knowledge of pharmacodynamic, pharmacokinetic or toxico- logical properties of individual enantiomers is still limited [18]. The facile synthesis of nanophase separated amphiphilic polymer conet- works allows the preparation of chiral membranes with precise mesh