Bender, Myron

The Chemisorption of Benzene R. B. Moves and P. B. Wells The Electronic Theory of Photocatalytic Reactions on Semiconductors Th. Wolkenstein Cycloamyloses as Catalysts David W. Griffiths and Myron L. Bender... 

Myron L. Bender, Department of Chemistry, Northwestern University, Evanston, Illinois (209)... 

Cycloamyloses as Catalysts David W. Griffiths and Myron L. Bender... 

Kliem Alexander S. J. Angyal Don M. Balcom Ernest I. Becker Myron L. Bender Charles E. Braun John Mann Butler Barbara K. Campbell Kenneth N. Campbell Marvin Carmack B. B. Corson J. E. Dayan B. D. Deacon Hugh B. Donahoe M, S. Dunn J. English, Jr. 

A Golan-Goldhirsh, DT Osuga, AO Chen, JR Whitaker. Effect of ascorbic acid and copper on proteins. In VT D Souza, J Feder, eds. The Bioorganic Chemistry of Enzymatic Catalysis An Eiomage to Myron L. Bender. Boca Raton, FL CRC Press, 1992, pp 61-76. 

We have made several artificial enzymes that use cyclodextrin to bind a substrate and then react with it by acylating a cyclodextrin hydroxyl group. This builds on earlier work by Myron Bender, who first studied such acylations [83]. We added groups to the cyclodextrin that produced a flexible floor, capping the ring [84]. The result was to increase the relative rate of cyclodextrin acylation by m-t-butylphenyl acetate from 365 relative to its hydrolysis rate in the buffer to a Complex/ buffer of 3300. We changed the substrate to achieve better geometry for the intracomplex acylation reaction, and with a p-nitrophenyl ester of ferroceneacrylic acid 10 we achieved a relative rate for intracomplex acylation of ordinary [3-cyclodextrin vs. hydrolysis of over 50 000 and a Vmax comparable to that for hydrolysis of p-nitrophenyl acetate by chymotrypsin... 

The cause of the scatter is the non-systematic influence of the substituent on the microscopic environment of the transition structure. The linear free energy relationship between product state XpyH (Equation 22) and the transition structure (Xpy. .. PO32 . . . isq) will be modulated by second-order non-systematic variation because the microscopic environment of the reaction centre in the standard (XpyH ) differs slightly from that (Xpy-PO ) in the reaction under investigation giving rise to specific substituent effects. These effects are mostly small. An unusually dramatic intervention of the microscopic medium effect may be found in Myron Bender s extremely scattered Hammett dependence of the reaction of cyclodextrins with substituted phenyl acetates.22 The cyclodextrin reagent complexes the substrate and interacts... 

The most important species in the mechanism for ester hydrolysis is the tetrahedral intermediate. Evidence in support of the existence of the tetrahedral intermediate was developed by Professor Myron Bender on the basis of isotopic labeling experiments he carried out at the University of Chicago. Bender prepared ethyl benzoate, labeled with the mass-18 isotope of oxygen at the carbonyl oxygen, then subjected it to acid-catalyzed hydrolysis in ordinary (unlabeled) water. He found that ethyl benzoate, recovered from the reaction before hydrolysis was complete, had lost a portion of its isotopic label. This observation is consistent only with the reversible formation of a tetrahedral intermediate under the reaction conditions ... 

To answer this question, Myron Bender investigated the hydroxide-ion-promoted hydrolysis of ethyl benzoate, with the carbonyl oxygen of ethyl benzoate labeled with 0. When he isolated ethyl benzoate from an incomplete reaction mixture, he found that some of the ester was no longer labeled. If the reaction had taken place by a one-step direct-displacement mechanism, all the isolated ester would have remained labeled because the carbonyl group would not have participated in the reaction. On the other hand, if the mechanism involved a tetrahedral intermediate, some of the isolated ester would no longer be labeled because some of the label would have been transferred to the hydroxide ion. By this experiment. Bender provided evidence for the reversible formation of a tetrahedral intermediate. 

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