Date of Award
Doctor of Philosophy
Benzyl, methyl, ethyl, and isopropyl(aquo)cobaloximes, RCo(dmgH)(,2)OH(,2), have been shown to undergo highly specific reactions in which a new carbon-carbon bond is formed in their reactions with aliphatic free radicals. Thus, benzylcobaloxime reacts with the (.)C(CH(,3))(,2)OH radical to yield PhCH(,2)C(CH(,3))(,2)OH and Co('II)(dmgH)(,2)OH(,2). With the exception of benzyl and meta-chlorophenyl radicals, this reaction appears quite general for aliphatic radicals. The kinetics of the reaction between the organocobaloximes and the (.)C(CH(,3))(,2)OH and (.)CH(CH(,3))OC(,2)H(,5) radicals have been determined by novel kinetic competition methods. The organocobaloximes undergo an acid-base equilibrium in which one of the O-H(.)(.)(.)O groups of the (dmgH)(,2) pseudo-macrocycle is protonated. Both the protonated and unprotonated forms of the cobaloxime react, with k(,obs) at a fixed acid concentration related to the rate constants for the reaction of the protonated (k(,a)) and unprotonated (k(,b)) forms of the organocobaloxime by;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI);The values obtained for the (.)C(CH(,3))(,2) radical are: (alkyl, 10('-6) k(,a)/M('-1) s('-1), 10('-6) k(,b)/M('-1) s('-1)) benzyl, 12.8 (+OR-) 0.60, 5.2 (+OR-) 0.2; methyl, 1.2, 0.71; ethyl, 0.79, 0.64; isopropyl, 0.49, 0.41. Corresponding values for the (.)CH(CH(,3))OC(,2)H(,5) radical are: benzyl, 19 (+OR-) 1, 5.9 (+OR-) 0.7; methyl, 1.7, 1.3; ethyl, 1.1, 0.66; isopropyl, 0.60, 0.60. The data are interpreted in terms of an addition-elimination mechanism involving one of the dimethylglyoxime ligands of the organocobaloxime;The reduction of Co(NH(,3))(,5)F('2+) by the (.)C(CH(,3))(,2)OH and(.)CH(CH(,3))OC(,2)H(,5) radicals has been studied by novel competitionmethods involving analysis of the fluoride ion produced in thereduction. The rate constants obtained at 25.0(DEGREES)C and 1.0M ionic;strength are (2.2 (+OR-) 0.3) x 10('6) M('-1) s('-1) and (1.1 (+OR-) 0.2) x 10('6) M('-1) s('-1), (.)C(CH(,3))(,2)OH and (.)CH(CH(,3))OC(,2)H(,5) radicals, respectively;('1)DOE Report IS-T-1034. This work was performed under ContractW-7405-Eng-82 with the Department of Energy.
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Ronnie Charles McHatton
McHatton, Ronnie Charles, "Kinetics and mechanisms of the reactions of aliphatic free radicals with organocobaloximes and fluoropentaamminecobalt(III) ion, and of iron(III) with methylrhodoxime " (1982). Retrospective Theses and Dissertations. 8368.