Toward Efficient Synthesis of Chiral Zeolites: A Rational Strategy for Fluoride‐Free Synthesis of STW‐Type Zeolite. Issue 45 (31st August 2020)

• Record Type: Journal Article
• Authors: Shinno, Yuki; Iyoki, Kenta; Ohara, Koji; Yanaba, Yutaka; Naraki, Yusuke; Okubo, Tatsuya; Wakihara, Toru
• Is Part Of: Angewandte Chemie international edition. Volume 59:Issue 45(2020)
• Page Start: 20099
• Page End: 20103
• Publication Date: 2020-08-31
• Subjects: crystal growth -- dry gel conversion -- fluoride-free synthesis -- STW -- zeolites; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202008233
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: The STW‐type zeolite is attractive for developing novel enantioselective syntheses/separation of chiral compounds because it is the only chiral zeolitic microporous material whose enantioenriched synthesis has been achieved. In addition to the conventional industries in which zeolites are used, STW should have diverse industrial applications in the pharmaceutical and food industries. However, the toxic and caustic fluoride required for synthesizing STW severely hinders its commercialization by mass production. Herein, we report the first example of fluoride‐free STW synthesis, in which the two roles of fluoride—formation of a zeolitic framework rich in tetravalent T‐atoms and promotion of double 4‐membered ring unit formation—were substituted by dry gel conversion and Ge addition, respectively. The STW obtained was highly crystalline, with a similar micropore volume and thermal stability as those of original fluoride‐based STW. Our approach is promising not only for the fluoride‐free synthesis of enantiomeric STW but also for general fluoride‐free syntheses. Abstract : Normally, toxic and caustic fluoride compounds are required for synthesizing the chiral STW‐type zeolite. Now, a fluoride‐free STW synthesis is possible. The roles of fluoride, that is, the formation of a framework rich in tetravalent T‐atoms and promotion of double 4‐membered ring formation, were substituted by dry gel conversion and Ge addition, respectively.