Synthesis and Olfactory Characterization of Sila-Methyl Pamplemousse and Related Odorants with a 2,2,5-Trimethyl-2-silahex-4-ene Skeleton
摘要:
The synthetic grapefruit odorant methyl pamplemousse (1a) has lately become an important trend odorant, and the related 2,2,5-trimethylhex-4-enes 2a-4a also possess interesting olfactory properties of fresh hesperidic and fruity-agrestic character. On the basis of the carbon/silicon switch strategy, the silicon-containing analogues silamethyl pamplemousse (1b) and 2b-4b were synthesized and studied for their olfactory properties (olfactory evaluation of the C/Si pairs 1a/1b-4a/4b). Si la substitution (C/Si exchange) was demonstrated to affect the olfactory properties substantially. The C/Si analogues la and 1b were found to be genuine grapefruit odorants, with the silicon compound 1b showing additional agrestic facets. As a proof of principle, it Was demonstrated that C/Si analogues can display a different mechanism and rate of degradation (degradation studies with la and 1b under acidic conditions).
Alkoxy-crosslinking one-component moisture curing compositions contain a polymer bearing (alkoxy)(methyl)silylalkyl-terminal groups, and specific silanes as described herein. The compositions exhibit improved shelf life and yet retain other desirable characteristics.
Alkoxysilyl-terminated preopolymers prepared by reacting an alkoxysilane with a prepolymer prepared by reacting a di- or polyisocyanate with both a low molecular weight diol or polyol and a high molecular weight polyol, the respective polyol components present within a specific ratio range, and giving rise to an increased content of urethane groups, and an inhomogenous distribution thereof exhibit high tensile strength and elongation, even without the use of fillers.
Alkoxysilane-terminated prepolymers prepared by reaction of a methylene-spaced isocyanate-reactive group-containing alkoxysilane in molar excess with an isocyanate-reactive prepolymer have high reactivity towards atmospheric moisture while preparing elastomers of high tensile strength and elongation.