- The surface nature of grignard reagent formation: Cyclopropylmagnesium bromide
-
The reaction of cyclopropyl bromide with managesium in diethyl directly ether yielded directly, during formation of the Grignard reagent, ～25-30% cyclopropane. Also formed in the reaction was ～25% cyclopropylmagnesium bromide. The reaction, when conducted in perdeuterated diethyl in diethyl ether in the presence of the radical trap deuterated dicyclohexylphosphine, showed that the cyclopropane is formed mainly by disproportionation of the cyclopropyl radicals on the magnesium surface (～85%) only a small amount (～15%) by reaction of a "freely radical" with the solvent. The reaction in methanol-O-d yielded almost exclusively 1-deuteriocyclopropane. These provide further experimental evidence that the basic assumption of the D-model "that all radicals leave the surface and diffuse freely in solution" is not valid.
- Walborsky,Zimmermann, Christoph
-
-
Read Online
- 1,4-diaryl-1-cyclopropyl-4-substituted butanes as insecticides and acaricides
-
The 1,4-diaryl-1-cyclopropyl-4-substituted butane pesticides of the following formula are effective as insecticides and acaricides: STR1 in which X and Y are independently hydrogen, halogen, alkyl, alkoxy, cycloalkylalkoxy, alkylcarbonyl, alkoxycarbonyl,
- -
-
-
- Solvent attack in grignard reagent formation from bromocyclopropane and 1-bromohexane in diethyl ether
-
In the reaction of magnesium with bromocyclopropane in diethyl ether at reflux, intermediate cyclopropyl radicals attack the solvent, giving cyclopropane (20-30 mol/100 mol of bromocyclopropane consumed) and solvent-derived products. In contrast, the similar reaction of 1-bromohexane gives no more than 0.5 mol of hexane from solvent attack by hexyl radicals. These data are consistent with calculations based on a mechanism (D Model) with freely diffusing intermediate radicals, in which cyclopropyl and hexyl radicals have similar reactivities in their conversions to Grignard reagents, but the cyclopropyl radical is approximately 1000 times as reactive toward the solvent as the hexyl radical.
- Garst, John F.,Ungváry, Ferenc,Batlaw, Rajnish,Lawrence, Kathryn Easton
-
p. 5392 - 5397
(2007/10/02)
-
