CAS: 1944-83-8

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An irritant to the eyes, skin and mucous membranes. A powerful oxidant. Preparative hazard. When heated to decomposition it emits acrid smoke and irritating fumes. See also PEROXIDES, INORGANIC; PEROXIDES, ORGANIC.

RTECS :

DG0875000

Two dialkyl peroxides are devised as kinetic probes for the heterogeneous electron transfer (ET) and studied using heterogeneous and homogeneous electrochemical techniques. The peroxides react by concerted dissociative ET reduction of the O-O bond.
The only products isolated are the corresponding alcohols from a two-electron reduction as has been observed with other dialkyl peroxides studied to date under heterogeneous conditions.
However, a generated alkoxyl radical undergoes a rapid beta-scission fragmentation in competition with the second ET resulting in formation of acetone and a benzyl radical under homogeneous conditions. With knowledge of the rate constant for fragmentation and accounting for the diffuse double layer at the electrode interface, the heterogeneous ET rate constant to the alkoxyl radicals is estimated to be 1500 cm s(-1). The heterogeneous and homogeneous ET kinetics of the O-O bond cleavage have also been measured and examined as a function of the driving force for ET, deltaG(ET), using dissociative electron transfer theory. From both sets of kinetics, besides the evaluation of thermochemical parameters, it is demonstrated that the heterogeneous and homogeneous reduction of the O-O bond appears to be non-adiabatic.

2-methyl-1-phenyl-2-propyl hydroperoxide (MPPH)(1944-83-8) versus tert-butyl hydroperoxide (TBHP):The epoxidation of cyclohexene in acetonitrile under argon at room temperature on a titanium(lV)-containing MCM41 silica catalyst is faster and gives a greater final yield of cyclohexene oxide when the oxygen atom donor is 2-methyl-1-phenyl-2-propyl hydroperoxide (MPPH) than when it is tert-butyl hydroperoxide. This shown to be due to stronger retardation of the oxidation by tert-butyl alcohol (TBA) than by the alcohol derived from MPPH. The difference in retardation between these two alcohols is attributed to the greater hydrophilicity ofTBA. Acetonitrile is a better solvent for this reaction than isooctane, pyridine and a variety of alcohols. These solvent effects are attributed to the hydrophilic nature of the catalyst.