Reactions of (alkylperoxy)cobaloximes in acidic aqueous solutions

Journal Article · Wed Apr 22 04:00:00 EST 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00398a026· OSTI ID:6341945

Espenson, J H; Chen, J T

Bis(dimethylglyoximato)cobalt(III) complexes containing coordinated alkylperoxy groups have been studied. The compounds examined are (1) ROOCo(dmgH)/sub 2/(pyridine) complexes with R = isopropyl, 2-butyl, cyclopentyl, benzyl, and isopropyl-d/sub 7/ and (2) (CH/sub 3/)/sub 2/CHOOCo(dmgH)/sub 2/L complexes with L = pyridine, piperidine, water, and ammonia. The complexes react wtih aqueous perchloric acid to form the cobalt(III) product (H/sub 2/O)Co(dmgH)/sub 2/L/sup +/ and a mixture of ketone and hydroperoxide. The organic products are formed in parallel pathways, each by a kinetic equation having the same algebraic form, and are the products of respective oxygen-oxygen and cobalt-oxygen bond cleavage reactions. Kinetic data were determined as a function of (H/sup +/) and, in the case of the 2-butyl complex, temperature. The rate constants for reactant disappearance and of product formation were determined, as was the ratio of ketone to hydroperoxide in the products. An important preequilibrium is the protonation of the oxime oxygens; the equilibrium constant varies in a way which reflects the basicity of the axial ligand L. The kinetic data and other results can be used to formulate a separate pathway leading to each product. Hydroperoxide formation is best accounted for by a pathway in which internal proton transfer from H/sup +/ bound to oxime oxygen occurs. Ketone production, on the other hand, shows an appreciable kinetic isotope effect: k/sup H//k/sup D/ = 8.9 +- 1.5, suggesting C-H bond breaking is a major part of the activation process.

• Research Organization: Iowa State Univ., Ames
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 6341945
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Journal Issue: 8 Vol. 103:8; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
AMINES
AQUEOUS SOLUTIONS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COBALT COMPLEXES
COMPLEXES
DEUTERIUM
DISPERSIONS
HYDROGEN ISOTOPES
HYDROXY COMPOUNDS
ISOTOPE EFFECTS
ISOTOPES
KINETICS
LIGHT NUCLEI
MIXTURES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIMES
REACTION KINETICS
SOLUTIONS
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES