- Electrophilic bromination of specifically deuterated cyclohexenes: A combined experimental and theoretical investigation
-
The electrophilic addition of Br2 to specifically deuterated cyclohexenes (1-5) was studied methanol (MeOH) by stopped-flow kinetics in order to determine a deuterium kinetic isotope effect (DKIE) for the various isotopomers. The DKIE for bromi
- Slebocka-Tilk,Neverov,Motallebi,Brown,Donini,Gainsforth,Klobukowski
-
-
Read Online
- Deuterium Isotope Effect in Vinyl Radical Combination/Disproportionation Reactions
-
The deuterium isotope effect for the vinyl radical combination and disproportionation reactions have been investigated.Protonated or deuterated vinyl and methyl radicals are produced from the 193 nm photolysis of protonated or perdeuterated methyl vinyl ketone.On the basis of product yield measurements, no isotope effect for the combination reactions of either vinyl-vinyl or vinyl-methyl has been observed.From the relative yields of ethylene, an isotope effect of kH/kD = 1.20 is determined for the vinyl-vinyl disproportionation reaction.
- Fahr, Askar,Laufer, Allan H.
-
p. 262 - 264
(2007/10/02)
-
- Hydrogenation of Conjugated Dienes and Isomerization of Butenes on CdO, Co3O4 and Cr2O3
-
Deuteration of buta-1,3-diene, 2-methylbuta-1,3-diene and penta-1,3-diene selectively yielded but-2-ene, 2-methylbut-2-ene and 1,4-2H2>pent-2-ene on CdO and Co3O4, and but-1-ene, 2-methylbut-1-ene and 4,5-2H2>pent-2-ene on Cr2O3, respectively.These results imply that the selectivity for 1,2- and 1,4-hydrogen addition is maintained in hydrogenation of conjugated dienes, i.e. 1,4-addition on CdO and Co3O4, and 1,2-addition on Cr2O3.The hydrogenation of buta-1,3-diene using a 1:1 mixture of H2 and D2 gave 2H2>but-1-ene in larger amounts than the 2H0>isomer on Cr2O3.An isotope effect smaller than unity was interpreted by prefential adsorption of D2 on the Cr2O3 surface.Formation of 2H1>butene was dominant in deuteration of buta-1,3-diene, indicating that residual hydrogen participates in the reaction; the amount corresponded to 7 times as much as that of chemisorbed hydrogen at room temperature.Co-isomerization of 2H0> and 2H8>but-1-ene yielded, selectively, 2H0>but-2-ene on CdO.Hydrogenation of buta-1,3-diene with a 1:1:1 mixture of H2, HD and D2 also gave 2H0>butene isomers selectively on CdO.These results infer that one intermediate species for hydrogenation of buta-1,3-diene is closely related to that for isomerization of butenes, and these reactions occur through a ?-allylic anion intermediate on CdO.
- Suzuki, Takashi,Tanaka, Katsumi,Toyoshima, Isamu,Okuhara, Toshio,Tanaka, Ken-ichi
-
p. 1213 - 1226
(2007/10/02)
-
- Hydrogen Transfer Reactions, 9. Synthesis and Analytics of Selectively Deuterated 1,4-Cyclohexadienes and 1,4-Dihydronaphthalenes
-
Five isotopomers of 1,4-cyclohexadiene (1a - e) and four of 1,4-dihydronaphthalene (2a - d) have been synthesized in an isotopomeric purity sufficient for mechanistic experiments.
- Brock, Martin,Hintze, Horst,Heesing, Albert
-
p. 3718 - 3726
(2007/10/02)
-