Deuterium butene

The recovered 2-butene contained small amounts of deuterium. 

Copper-nickel alloy films similarly deposited at high substrate temperatures and annealed in either hydrogen or deuterium were used to study the hydrogenation of buta-1,3-diene (119) and the exchange of cyclopentane with deuterium (120). Rates of buta-1,3-diene hydrogenation as a function of alloy composition resemble the pattern for butene-1 hy-... 

Bei Anwendung eines DBr—AlBr3-Katalysators auf n- oder iso-Butan fanden Pines und Wakher (152) keine Isomerisierung und nur 6 bzw. 9% Austausch des Deuteriums. Bei Gegenwart von 0,1 Mol n-Buten werden... 

The r/zreo-3-deutero-2-trimethylstannylbutane that Hannon and Traylor158 used to determine the stereochemistry of the hydride transfer reaction and to shed light on the mechanism of this reaction was synthesized using the reactions in Scheme 22. Each of the reactions in Scheme 22 is stereo specific and the analysis showed that the product was at least 97% r/rreo-3-deutero-2-trimethylstannylbutane. If the elimination reaction from t/zreo-3-deutero-2-trimethylstannylbutane occurs with an awh -periplanar stereochemistry, the products shown in Scheme 23 will be obtained. Thus, if the elimination occurs by an awft -periplanar stereochemistry, all the fraws-2-butene will be monodeuterated while the ds-2-butene will not be deuterated. A syw-periplanar elimination from f/zreo-3-deutero-2-trimethylstannylbutane, on the other hand, would give the products shown in Scheme 24. If this occurs, the cw-2-butene will contain one deuterium atom and the fraws-2-butene will contain none. 

The results from these experiments also allowed Hannon and Traylor to determine the primary and secondary hydrogen deuterium kinetic isotope effects for the hydride abstraction reaction. If one assumes that there is no kinetic isotope effect associated with the formation of 3-deutero-l-butene, i.e. that CH2=CHCHDCH3 is formed at the same rate (k ) from both the deuterated and undeuterated substrate (Scheme 25), then one can obtain both the primary (where a deuteride ion is abstracted) and the secondary deuterium... 

The primary hydrogen-deuterium kinetic isotope effect is obtained from the percent cw-2-butene obtained from the deuterated and undeuterated stannanes. This is possible because a hydride and a deuteride are transferred to the carbocation when the undeuterated and deuterated stannane, respectively, forms c -2-butene. The secondary deuterium kinetic isotope effect for the hydride transfer reaction is obtained from the relative amounts of fraws-2-butene in each reaction. This is because a hydride is transferred from a deuterated and undeuterated stannane when trans-2-butene is formed. 

Direct experimental evidence for the trans elimination in E2 reactions has been obtained from deuterated -2-bromobutane (the deuterium atom occupies position 3). This compound on dehydrobromination forms trans and cis butene-2 in the ratio of 6 1... 

The use of several different experimental techniques to investigate a given system is likely to be particularly revealing. Two noteworthy examples in which stereochemical considerations had a part are provided by Taylor and Dibeler (8) on the reactions of deuterium with the butenes on nickel wires and by Meyer and Burwell (9, 10) on the deuteration of multiply unsaturated hydrocarbons. 

The addition of deuterium to 1,3-butadiene yields mainly 1-butene and isotopic distribution in these products is nearly identical and 70% of the initial product corresponds to simple 1,2 or 1,4 addition. Meyer and Burwell suggest that 1,3-butadiene is adsorbed on the surface in the trans conformation. Addition of deuterium to a terminal earbon atom produces an allylic species which is a common intermediate for the formation of both major products, I-butene and trans-2-butene. 

This assignment is supported, indirectly, by the measured activities of these experiments. For example, the activities were measured to be (in M/g-catalyst hour) 0.98 (MS-Hz) 0.61 (MS-Dz) 180 (US-Hz) and 190 (US-Dz). Hence, the 250-fold greater activities of the ultrasound systems is consistent with the expected, more rapid, statistical C-H/D dissociation process as compared to the conventional (e.g., stirred/silent) mediated systems. Additional support for this model arises from a study of gas phase cA-2-butene isomerization to fra/rs-2-butene [15] at 291 K. Here the c O extrapolated trans deuterium number of -0.27 is supportive of C3-H/D elimination predicted by tra/jsition-state theory in this system at thermal equilibrium (e.g., vibrational temperature equal to tra/jslational temperature). 

Other systems for which the results cannot be explained by energy transfer include the ketone sensitized isomerization of / -methylstyrene, 1,2-dichloro-ethylene and 2-butene studied by Caldwell,147,148 deuterium exchange between acetone-d8 and tetramethylethylene reported by Japar, Pomerantz, and Abrahamson,149 and the acetone sensitized isomerization of 1-methoxy-l-butene examined by Turro and Wriede.71... 

Reduction with Deuterium. Cyanocobaltate(II) (42.6 ml. of solution, 0.15M cobalt, CN/Co = 5.1) was formed in an atmosphere containing equimolar quantities of deuterium and butadiene and stirred for 15 minutes, at which time a sample of the atmosphere was taken for analysis, trans-2-Butene (26%), cis-2-butene (0.51%), ana 1-butene (4.1%) as well as unreacted butadiene (53%) were separated by vapor phase chromatography and each fraction was submitted for mass spectrographic analysis. The presence of di-, mono-, and nondeuterated species was detected in each butene fraction, while the butadiene was shown to contain small quantities of mono- and dideutero species. 

In homogeneous systems the tight ion pair 12 is formed, the collapse of which depends on the electronic effects and the steric interactions of the substituents. The stability of this ion pair determines the intramolecularity of the rearrangement.121 For example, when (+)-3-phenyl-l-butene was isomerized in tert-BuOK-tert-BuOD, the recovered starting material was deuterium-free and exhibited the same rotation as the starting material, and the product m-2-phenyl-2-butene contained 0.46 deuterium at C(4). This indicates that the isomerization is at least 54% intramolecular.126 Proton migration in perdeutero-l-pentene in ferf-BuOK-DMSO was demonstrated to proceed almost exclusively in an intramolecular manner.127... 

The relative contribution of the two mechanisms to the actual isomerization process depends on the metals and the experimental conditions. Comprehensive studies of the isomerization of n-butenes on Group VIII metals demonstrated179-181 that the Horiuti-Polanyi mechanism, the dissociative mechanism with the involvement of Jt-allyl intermediates, and direct intramolecular hydrogen shift may all contribute to double-bond migration. The Horiuti-Polanyi mechanism and a direct 1,3 sigma-tropic shift without deuterium incorporation may be operative in cis-trans isomerization. 

For example, the ene reaction proceeds stereoselectively in a suprafacial manner specifically, oxygen attack and hydrogen removal take place on the same side of the double bond. As a result, neither racemization of optically active com-pounds nor cis-trans isomerization occurs. Diradical or dipolar intermediates are not consistent with these observations. The lack of a Markovnikov-type directing effect also rules out dipolar intermediates.360 399 Isotope effects observed in the reaction of different deuterium-labeled 2,3-dimethyl-2-butenes indicated that... 

The monohydrogenation of conjugated dienes can occur by either 1,2 or 1,4 addition. 1-Butene (53%) and trans-2-butene (42%) are the main products in the hydrogenation of 1,3-butadiene on palladium with only a small amount of cis-2-butene.68 Deuterium distribution reveals that the trans isomer is produced by 1,4 addition. 

Early studies with deuterium-labeled57 58 and l4C-labeled compounds59 60 established that cleavage of the double bonds occurs. For example, the degenerate metathesis of 2-butene and perdeutero-2-butene57 results in the formation of [l,l,l,2-2H4]-2-butene as the only new labeled compound [Eq. (12.11)] which is consistent with alkylidene exchange [Eq. (12.10)] ... 

---