Kinetics and mechanisms of the reactions of aliphatic free radicals with organocobaloximes and fluoropentaamminecobalt(III) ion, and of iron(III) with methylrhodoxime. [C(CH/sub 3/)/sub 2/OH and C(CH/sub 3/)OC/sub 2/H/sub 5/ radicals]

Technical Report · Wed Dec 01 04:00:00 EST 1982

OSTI ID:6654621

McHatton, R C

Benzyl, methyl, ethyl, and isopropyl(aquo)cobaloximes, RCo(dmgH)/sub 2/OH/sub 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/sub 3/)/sub 2/OH radical to yield PhCH/sub 2/C(CH/sub 3/)/sub 2/OH and Co/sup II/(dmgH)/sub 2/OH/sub 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/sub 3/)/sub 2/OH and CH(CH/sub 3/)OC/sub 2/H/sub 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)/sub 2/ pseudo-macrocycle is protonated. Both the protonated and unprotonated forms of the cobaloxime react, with K/sub obs/ at a fixed acid concentration related to the rate constants for the reaction of the protonated (k/sub a/) and unprotonated (k/sub b/) forms of the organocobaloxime by k/sub obs/ = k/sub b/ + k/sub a/K/sub H/(H/sup +/) divided by 1 + K/sub H/(H/sup +/). Rate constants for the radicals are provided. 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/sub 3/)/sub 5/F/sup 2 +/ by the C(CH/sub 3/)/sub 2/OH and CH(CH/sub 3/)OC/sub 2/H/sub 5/ radicals has been studied by novel competition methods involving analysis of the fluoride ion produced in the reduction. The rate constants obtained at 25.0/sup 0/C and 1.0M ionic strength are (2.2 +- 0.3) x 10/sup 6/ M/sup -1/ s/sup -1/ and (1.1 +- 0.2) x 10/sup 6/ M/sup -1/ s/sup -1/, C(CH/sub 3/)/sup 2/OH and CH(CH/sub 3/)OC/sub 2/H/sub 5/ radicals, respectively. 19 figures, 18 tables.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6654621
• Report Number(s): IS-T-1034; ON: DE83004856
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400301 -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AMINES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COBALT COMPLEXES
COMPLEXES
DATA
EXPERIMENTAL DATA
FLUORINE COMPOUNDS
HALOGEN COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
KINETICS
LIGANDS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIMES
RADICALS
REACTION KINETICS
REDUCTION
TRANSITION ELEMENT COMPLEXES