Halpern, Jack

Kenneth B. Bischoff Donald G. Crosby Robert E. Feeney Jeremiah P. Freeman E. Desmond Goddard Jack Halpern Robert A. Hofstader James D. Idol, Jr. 

David L. Allara Kenneth B. Bischoflf Donald G. Crosby Donald D. Dollberg Robert E. Feeney Jack Halpern Brian M. Harney Robert A. Hofstader... 

Fred Basolo Raymond F. Boyer Jack Halpern George W. Irving Amel R. Menotti C. M. Sliepcevich Leo H. Sommer Fred R. Whaley William A. Zisman... 

Jack Halpern What is the rate constant for the aquo ion in this series for comparison ... 

Jack Halpern I want to ask Dr. Dessy two questions. Sometime ago we looked at substantially the same reaction (i.e., decomposition of methoxycarbonyl mercuric acetate) in aqueous solution, and we found also that this decomposition is catalyzed by hydrogen ion and by chloride ion. The rate is first-order in (H+), but we found that in addition to a path first-order in (Cl-) there were also appreciable contributions from higher order paths, certainly second-order and possibly also third. This implies that the process is further aided by coordination of more than one halide to the metal. I wondered whether there were any corresponding indications in these solvent systems. 

Jack Halpern Perhaps I have more reason than anyone else to be disposed to the view that 7r-complexing is an important step of the insertion reaction, because I think that possibly we have the only reasonably clear cut case of an olefin insertion reaction where a complex is clearly implicated. This is the ruthenium chloride-catalyzed hydrogenation of certain olefins, which almost certainly involves the insertion of the olefin into a ruthenium hydrogen bond and where certainly a ruthenium olefin complex is involved as an observable reactant. Nevertheless, I am not at all sure to what extent this is a general or necessary feature of such insertion reactions. The important question is whether one or two coordination positions on the metal ion are involved in the transition state of the insertion reaction. For example, if one considers the insertion of an olefin, say into an M—X bond, then the transition state may look something like ... 

Raymond F. Boyer John H. Fletcher Jack Halpern Wayne W. Hilty George W. Irving Walter C. Saeman Calvin L. Stevens Calvin A. Vanderwerf George A. Watt... 

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