نتایج جستجو برای: alkenes
تعداد نتایج: 5720 فیلتر نتایج به سال:
Copulatory responses of male Glossina austeni (Newstead) (Diptera: Glossinidae), that were elicited after contact with frozen female tsetse, were not observed after solvent washing of cuticular lipids. Chromatographic analysis of extracts from laboratory-reared and field-collected G. austeni females yielded natural hydrocarbons that were highly stimulatory to males. Most of this activity was pr...
Alkenes are oxidized rapidly in the atmosphere by addition of OH and subsequently O2 leading to the formation of β-hydroxy peroxy radicals. These peroxy radicals react with NO to form β-hydroxy nitrates with a branching ratio α. We quantify α for C2–C8 alkenes at 295 K± 3 and 993 hPa. The branching ratio can be expressed as α = (0.045± 0.016)×N−(0.11± 0.05)whereN is the number of heavy atoms (e...
In a Heck reaction using multi-substituted alkenes, the initial syn-carbopalladation sets two vicinal stereocenters by virtue of the migratory insertion process. Unfortunately, the resultant Pd–alkyl undergoes facile b-hydride elimination, which generally eliminates the stereochemistry imparted by migratory insertion. Recently, we have reported a modern variant of the Heck reaction, wherein the...
The one-pot efficient synthesis of novel functionalized organoselenium compound by bis-alkoxyselenenylation alkenes with selenium dibromide and alcohols was developed. reaction the cyclopentene or cyclohexene in system alcohol/sodium bicarbonate/methylene chloride at room temperature afforded bis(2-alkoxycycloalkyl) selenides 90–99% yields. regioselective method for bis-alkoxylation terminal de...
The overall rate constants of the NO reaction with chloroalkylperoxy radicals derived from the Cl-initiated oxidation of several atmospherically abundant alkenes-ethene, propene, 1-butene, 2-butene, 2-methylpropene, 1,3-butadiene, and isoprene (2-methyl-1,3-butadiene)-were determined for the first time via the turbulent flow technique and pseudo-first-order kinetics conditions with high-pressur...
An efficient method for the cocyclotrimerization of bicyclic alkenes and benzynes catalyzed by palladium phosphine complexes to give the corresponding norbornane anellated 9,10-dihydrophenanthrene derivatives is described. Bicyclic alkenes 1a-i undergo [2 + 2 + 2] cocyclotrimerization with benzynes generated from precursors 2a-d [2-(trimethylsilyl)phenyl triflate (2a), 4,5-dimethyl-2-(trimethyl...
Complexes of the type ZnS6(TMEDA), ZnS4(PMDETA), and ZnS4(Me3TACN) react with electrophilic alkenes to give dithiolene complexes ZnS2C2R2(amine)n. The Me3TACN complex is the most reactive, while the more conveniently prepared PMDETA complex also undergoes this reaction at useful rates. The following alkenes were successfully tested: C2H2(CO2Me)2 (cis and trans isomers), C2H3(CO2Me), C2H3(CN), 1...
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