Organosilicon chemistry. Part 21. Reactions of NN-bistrifluoromethylamino-oxyl and perfluoro(2,4-dimethyl-3-oxa-2,4-diazapentane) with vinylsilanes, and pyrolysis of the resulting adducts

Abstract

The oxyl (CF₃)₂N·O˙ and the oxadiazapentane (CF₃)₂N·O·N(CF₃)₂ on reaction with the vinylsilanes CH₂:CH·SiX₃, CH₂:CCl·SiX₃, and CHCl:CH·SiX₃ give the corresponding adducts in high yield; with the silane cis-MeCH:CH·SiCl₃ reaction with the diazapentane affords the 1 : 1 adduct (50%) and the allylic substitution product (CF₃)₂N·O·CH₂·CH:CH·SiCl₃(50%). The adducts on thermolysis generally rearrange, e.g. RCH₂·CH(SiX₃)·O·N(CF₃)₂→RCH₂·CH(O·SiX₃)·N(CF₃)₂[R =(CF₃)₂N·O or (CF₃)₂N], but those containing two or three fluorine substituents on silicon, and/or chlorine in the alkyl group, undergo elimination reactions. Three different modes of elimination can occur involving: (i) nucleophilic attack by fluorine in the α-(CF₃)₂N·O group on silicon to eliminate a fluorosilane and perfluoro-2-azapropene and form a carbonyl compound, e.g.(CF₃)₂N·O·CH₂·CH(SiF₃)·O·N(CF₃)₂→ SiF₄+ CF₃N:CF₂+(CF₃)₂N·CH₂·CHO; (ii) nucleophilic attack by an α-chlorine atom on silicon to eliminate a chlorosilane and form an amide, e.g.(CF₃)₂N·CH₂·CCl(SiCl₃)·O·N(CF₃)₂→ SiCl₄+(CF₃)₂N·CH₂·CO·N(CF₃)₂; and (iii) intramolecular elimination of bis(trifluoromethyl)amine followed by intermolecular elimination of hexafluorodisilane and chloroketen to give an ester, i.e.(CF₃)₂N·O·CHCl·CH(SiF₃)·O·N(CF₃)₂→(CF₃)₂NH +(CF₃)₂N·O·CHCl·CO·SiF₃ followed by 2(CF₃)₂N·O·CHCl·CO·SiF₃→ Si₂F₆+ CHCl:C:O +(CF₃)₂N·O·CHCl·CO₂·N(CF₃)₂.