The reaction of a silane with ozone results in the quantitative conversion of the Si-H bond to the Si-OH moiety. The mechanism of this oxidation has been elucidated by examination of: (a) relative rate data, (b) substituent effects, (c) deuterium isotope effects, (d) low-temperature nmr, and (e) uv spectroscopy. The mechanism proposed involves fast, reversible complexation of ozone (acting as a nucleophile) with the silicon atom, rate-determining electrophilic attack of ozone on the hydridic hydrogen, and decomposition into a R3Si • • OH radical pair which recombines to produce the silanol. From the relative rate data and substituent effects, a Hammett-like value, 8 *, characteristic of substituents bound to silicon, is derived.

No abstract

The behavior of the Reformatsky reagent prepared discretely from zinc and ethyl a-bromoisobutyrate in etherbenzene has been examined. Titration with a standard solution of fluorenone and vapor phase chromatography demonstrate that under normal conditions approximately 70y0 of active reagent is produced along with some 30YG of a dimeric substance which affords ethyl isobutyrylisobutyrate on work-up. This dimeric product may be produced by zinc reduction of ethyl 7-bromoisobutyrylisobutyrate, whose presence in small amounts may be demonstrated on work-up, but it is shown that it can also be produced from the active reagent alone, with the elimination of the elements of ethoxyzinc bromide. The adduct formed from this reagent and 9-fluorenone in an instantaneous reaction is unusually prone to decompose into the ketone and ethyl isobutyrate on treatment with even weak bases. This suggests that the initial adduct has little ionic character in the D-oxido portion, and the infrared spectrum of a solution of the adduct implies a zinc chelate structure.

No abstract

No abstract