Reaction of Organoelement Hydrides R3EH (E = Si, Ge) with Metal tert-Butylate (M = Al, Ti)-tert-Butyl Hydroperoxide Oxidative Systems

Abstract

Trialkyl(aryl)silanes and -germanes effectively react with metal (Al, Ti) tert-butylate3tert-butylhydroperoxide under mild conditions (room temperature, benzene or tetrachloromethane) mainly by the element3hydrogen bond. The character of the products depends on the nature of the element, the structure of the radical bound to it, and the solvent. The process is radical in nature. It includes the stages of formation of element-centered radicals and their reaction with the oxygen generated by the system. The intermediate organometallic peroxides can also acts as oxidants for the element (Si, Ge)3hydrogen bonds.The oxidative activity of organosilicon and organogermanium hydrides depends on the structure of the radicals bound with the heteroatom and the nature of the oxidant. Potassium permanganate [1], hydrogen peroxide on a Zeolite catalyst [2], and perbenzoic acid [3] convert trialkyl(aryl)silanes to corresponding hydroxy derivatives. Triethylsilane and triethylgermane react with mineral acids (H 2 SO 4 , HNO 3 ), as well as with Ag 2 O at the boiling points of the hydrides to form siloxane and germanoxane [4].Over the past years dimethyldioxirane [5, 6] has been offered as a mild oxidant that converts trialkylsilanes of various structure to hydroxysilanes. The reaction involves the Si3H bond and occurs at temperatures ranging from 370oC to 20oC with a high conversion and selectivity by the molecular and radical mechanisms, the first prevailing.The reaction of organosilicon hydrides with ozone at 370oC to 380oC involves formation of hydrotrioxides R 3 SiOOOH [639]. At elevated temperatures, the latter decompose with liberation of singlet oxygen, hydroxysilane, and, to a smaller degree, siloxane [6,8]. The mechanism of the decomposition of silicon hydrotrioxides is mostly molecular.Silicon and germanium monohydrides are sufficiently stable toward free oxygen. Triphenylsilane undergoes oxidation to Ph 3 SiOH, initiated by benzoyl peroxide (C 6 H 6 , 95oC) [10]. However, the ability of R 3 GeH to oxidation is much dependent on the structure of the radical. Triphenylgermane is extremely slowly oxidized by atmospheric oxygen [11,12], but tricyclohexylgermane is fast oxidized on exposure to air to form tricyclohexylgermanol.Hence, E3H can bonds can be oxidized with a fairly broad range of reagents, and the reactions are accelerated by radical initiators. There is no information in the literature concerning reactions of silicon and germanium hydrides with oxidative systems comprising organoelement compounds or element alcoholates and hydroperoxides, that are known as effective and selective oxidants for C3H bonds in various substrates [13].It was previously shown that aluminum and titanium tert-butylates (I and II) react with tert-butylhydroperoxide (III) at a 1 : 2 ratio under mild conditions (C 6 H 6 , CCl 4 , 20oC) via formation of metalcontaining trioxides [14,15]. The latter decompose with evolution of oxygen, including singlet oxygen, as well as homolytically by the peroxide bonds with generation of alkoxyl and pero...

Synthesis and Characterization of Potential Impurities of Canagliflozin

“…Molecular weight was found extra by 32 mass units than that of canagliflozin. [15] Later spectroscopic analysis confirmed the replacement of benzylic proton with peroxide (-OOH) functional group. One-dimensional ( 1 H) and two-dimensional ( 1 H-1 H ROESY and 1 H-1 H TOCSY) NMR measurements on canagliflozin impurity-D was recorded in DMSO-d 6 (600 mL) on a Bruker Avance 400 MHz NMR spectrometer.…”

“…Impurity-D & F are the degradation impurities observed during the degradation study of final drug substance. However impurity-E is process as well as degradation product of Imp-D. [15] These impurities were enriched in the lab using the peroxide mediated oxidation of canagliflozin and pure samples were isolated with the help of preparative HPLC. The impurity-D was found unstable at ambient temperature.…”