TOPIC: Development of Chiral Polymers for Enantioseparation
SPEAKER:Prof. Yoshio Okamoto，Nagoya University
TIME:October 24 (Monday)14:00 pm
VENUE:Room 528, Chemistry Building A (化学A楼528演讲厅)
INVITER:车顺爱 教授
 

Abstract: In 1979, we succeeded in the asymmetric synthesis of one-handed optically active polymer from an achiral triphenylmethyl methacrylate (TrMA) with a bulky ester group. This was the first example of the helix-sense-selective polymerization of an achiral monomer. The obtained polymer (PTrMA) exhibited unexpected high chiral recognition to many racemic compounds, and a practically useful chiral stationary phase (CSP) for high-performance liquid chromatography (HPLC) was successfully developed by coating the polymer on silica gel. In 1982, this CSP was commercialized as the first polymer-based CSP. With this CSP, many stereochemically interesting chiral compounds have been resolved. Through this study, we noticed that this separation method must be very useful and beneficial for studying many chiral compounds, particularly chiral pharmaceuticals, and we wanted to develop more practically useful CSPs for HPLC. For this purpose, we decided to use the 1,4-b-glucan, cellulose, as a starting polymer, since cellulose is a readily available chiral polymer and easily modified to esters and carbamates. Cellulose is also the most abundant polymer on the earth. Some esters, such as triacetate and tribenzoate, of cellulose had already been known to show good chiral recognition to many racemates as CSPs since 1974. However, the chiral recognition of its carbamate derivatives, such as trisphenylcarbamates, had not been reported for many years. In 1984, we synthesized cellulose trisphenylcarbamate and coated it on silica gel to use as CSP. This cellulose-based CSP exhibited excellent chiral recognition to a broad range of racemates, which enabled immediate commercialization with a commercial name, CHIRALCEL OC. We synthesized a series of phenylcarbamate derivatives with various substituents on the phenyl ring, and found that the derivatives, such as tris(3,5-dimethylphenylcarbamate) and tris(3,5-dichlorophenylcabamate), show higher chiral recognition. Analogous derivatives were also prepared using 1,4-a-glucan, amylose, and were found to show high chiral recognition different from that of the cellulose derivatives. These polysaccharide-based CSPs have been most frequently used to separate various racemates in many fields until recently.

Biography and Homepage (Yoshio Okamoto)

Yoshio Okamoto received his bachelor (1964), master (1966) and doctor degrees (1969) from Faculty of Science, Osaka University. In 1969, he joined Faculty of Engineering Science, Osaka University as Assistant Professor and spent two years (1970–72) at University of Michigan with Prof. Charles G. Overberger as a postdoctoral fellow. In 1983, he was promoted to Associate Professor, and in 1990 he moved to Nagoya University as Professor.

In 2004, he retired from Nagoya University with the title of Professor Emeritus and was appointed as Guest Professor of EcoTopia Science Institute, Nagoya University until 2009. Since 2009, he has been Distinguished Invited University Professor of Nagoya University. He has also been appointed as Chair Professor of Harbin Engineering University in China since 2007. His research interests include stereocontrol in polymerization reaction, optically active polymers and enantioseparation by HPLC.

He received Award of the Society of Polymer Science, Japan (1982), Chemical Society of Japan Award for Technical Development (1991), Chemical Society of Japan Award (1999), Molecular Chirality Award (1999), Chirality Medal (2001), the National Medal with Purple Ribbon (2002), Fujihara Prize (2005), Thomson Scientific Research Front Award 2007 (2007), SPSJ Award for Outstanding Achievement in Polymer Science and Technology (2009), and The Ryoji Noyori Prize (2010), Charles G. Overberger International Prize in Polymer Science (2011) and The Japan Academy Prize (2014).

 Homepage: http://chiral.apchem.nagoya-u.ac.jp/paper/paperlist.htm