Winstein, Saul

Willstaller, Richard. 524 Winstein, Saul. 375 Wittig, Georg, F. K., 720 Wiltig reaction, 720-722 mechanism of, 720-721 uses of. 722... 

As the norbornyl ion controversy evolved, it became a highly public and frequently very personal and bitter pnblic debate. Saul Winstein suddenly died in the fall of 1969, shortly after the Salt Lake City sym-posinm. To my regret, I seemed to have inherited his role in repre-... 

Saul Winstein (1912-1969) was bom in Montreal, Canada, and received his Ph.D. in 1938 at the California Institute of Technology. From 1942 to 1969, he was professor of chemistry at the University of California, Los Angeles, where he devoted his scientific career to the study of organic reaction mechanisms, particularly those involving carbocations. 

This lack of complete racemization in most SKd reactions is due to the fact that ioti pairs are involved. According to this explanation, first proposed by Saul Winstein, dissociation of the substrate occurs to give a structure in which the two ions are still loosely associated and in which the carbocation is effectively shielded from reaction on one side by the departing anion. If a certain amount of substitution occurs before the two ions fully diffuse apart, then a net inversion of configuration will be observed Figure 11.11). 

The structure of nonclassical carbocations, such as norbomenyl 3, has been the subject of debate since the 1950s when Saul Winstein published his milestone studies on the solvolysis of tosylated norbomenyl compounds. It was proposed that the norbomenyl cation should be represented as the nonclassical structure 4+, with a 3-center, 2-electron cyclic system (3c-2e), rather than as the classical equilibrium... 

Saul Winstein, handwritten 3-page obituary notice for Howard J. Lucas, H. J. Lucas Papers, Caltech Pauling, speaking about Lucas, in interview with John Heilbron, 2d of 2 sessions, 12, SHQP, Berkeley. Also, see Saltzmann, "Development of Physical Organic Chemistry," 592. 

Also in the 1930s, detailed studies about the thermodynamic stability of adducts of silver(I) with olefins were carried out by Howard Lucas and coworkers, who determined the equilibrium constants between the hydrated Ag+ ion and the corresponding cationic olefin silver(I) complex in dilute aqueous solutions of silver nitrate [25]. In the context of this work, Saul Winstein and Lucas made an initial attempt to describe the interaction between Ag+ and an olefin by quantum mechanics [26]. Assisted by Linus Pauling, they explained the existence of olefin silver(I) compounds in terms of resonance stabilization between the mesomeric forms shown in Fig. 7.4. Following this idea, Kenneth Pitzer proposed a side-on coordination of Ag+ to the olefin in 1945 and explained the stability of the corresponding 1 1 adducts as due to an argentated double bond , in analogy to his concept of the protonated double bond [27]. He postulated that the unoccupied s-orbital of silver(l) allowed the formation of a bond with the olefin, similar to the s-orbital of the proton. 

This is mainly the work of Philip Warner who also (cf. Ref. 44) appears to have been introduced into the field of propellanes by Saul Winstein in work concerned with the protonation of l,6-methano[10]annulene, work in which they ruled out the presence of a propellane-type cation". ... 

T. Hanafusa. H. Yamaoka, K. Ohkota, and T. Hanafusa, Bull. Chem. Soc. Jpn, 49, 245 (1976) have solvolyzed an acetate of a homochromone and rationalize the results in terms of an oxahomonaphthalenium ion. But in addition to this chemical point, T. Hanafusa combines solvolytic work on propellanes with which he was associated with Saul Winstein (cf. Refs 214-216 in Ref. 1). 

Elegant work by Saul Winstein (of the University of California, Los Angeles) has revealed the detailed behavior of ion pairs that are intermediates in certain cases of solvolysis tight (or intimate) ion pairs, the cation of which is free enough to pivot about and lose configuration, and yet is held tightly enough that recombination to the covalently bonded compound is the favored process loose (or solvent-separated) ion pairs, the cation of which is susceptible to attack by outside nucleophiles. 

Richard F. Heck (bom 1931) was a student of Saul Winstein (UCLA) and Vladimir Prelog (ETH Zurich). He started mechanistic work on homogeneous catalysis in 1956 when he entered Hercules Inc. (Wilmington, Del., USA) as a research chemist. He pioneered the elucidation of reaction mechanisms of organometallic processes, e. g., hydro-formylation and Ziegler-Natta polymerization, and published a number of key papers about the chemical and mechanistic backgrounds of these reactions. He was a chemistry professor at the University of Delaware from 1971 until his retirement in 1989. For the Heck reaction the reader is referred to Section 3.1.6. 

Saul Winstein was the first to explain why extra inverted product generally is formed in an SnI reaction. He postulated that dissociation of the alkyl halide initially results in the formation of an intimate ion pair. In an intimate ion pair, the bond between the carbon and the leaving group has broken, but the cation and anion remain next to each other. This species then forms a solvent-separated ion pair—an ion pair in which one or more solvent molecules have come between the cation and the anion. Further separation between the two results in dissociated ions. 

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