Deuterium butane

Sometimes the strongly basic properties of Gngnard reagents can be turned to synthetic advantage A chemist needed samples of butane specifically labeled with deuterium the mass 2 isotope of hydrogen as shown... 

The photo-Kolbe reaction is the decarboxylation of carboxylic acids at tow voltage under irradiation at semiconductor anodes (TiO ), that are partially doped with metals, e.g. platinum [343, 344]. On semiconductor powders the dominant product is a hydrocarbon by substitution of the carboxylate group for hydrogen (Eq. 41), whereas on an n-TiOj single crystal in the oxidation of acetic acid the formation of ethane besides methane could be observed [345, 346]. Dependent on the kind of semiconductor, the adsorbed metal, and the pH of the solution the extent of alkyl coupling versus reduction to the hydrocarbon can be controlled to some extent [346]. The intermediacy of alkyl radicals has been demonstrated by ESR-spectroscopy [347], that of the alkyl anion by deuterium incorporation [344]. With vicinal diacids the mono- or bisdecarboxylation can be controlled by the light flux [348]. Adipic acid yielded butane [349] with levulinic acid the products of decarboxylation, methyl ethyl-... 

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... 

Recently, Rooney (80) expressed the view that the a,j8 exchange process involved tt olefin complexes and asserts that this explains the pattern of exchange on a palladium film of deuterium with 1,1-dimethylcyclo-butane. Its failure to exhibit appreciable multiple isotopic exchange was attributed to the difficulty of forming a tt olefin complex because of the strain in cyclobutene. 

Neutron diffraction has been used occasionally to determine the absolute configuration of deuterium-labeled stereogenic centers, such as R -CHD-R2 (Table 6) and R -C(CH3)(CD3)—R2 82, by internal comparison, i.e, determination of configuration relative to a second stereogenic center of known absolute configuration in the same compound (see Section 4.2.2 3.). For example, the absolute configuration of (-)-(2R)-butane-2-d-dioic acid (succinic acid), prepared from (-)-(25,37 )-2-hydroxybutane-3-rf-dioic acid (malic acid), was determined on the corresponding 1-phenylethylammonium salt (Table 6)83. 

The 7r-nature of the central bond in bicyclo[1.1.0]bulane is aptly demonstrated by its cycloaddition reaction with benzyne in 1,2-dichloroethane, from which two compounds 29 and 30 were isolated in moderate yield in a ratio of 6 1. The structures of the major and the minor compounds were identified as 3-phenylcyclobutene (29) and benzobicyclo[2.2.1]hex-2-ene (30), respectively.44 Deuterium labeling experiments showed that both products resulted from attack on bicy-clo[1.1.0]butane from the endo side.44... 

Direct evidence about the first step of activation of butane was obtained on a V-P oxide catalyst in the butane oxidation to maleic anhydride based on deuterium kinetic isotope effect (34). It was found that when a butane molecule was labeled with deuterium at the second and third carbon, a deuterium kinetic isotope effect of 2 was observed. No kinetic isotope effect was observed, however, if the deuterium label was at the first or fourth carbon. By comparing the observed and theoretical kinetic isotope effects, it was concluded that the first step of butane activation on this catalyst was the cleavage of a secondary C—H bond, and this step was the rate-limiting step. 

With palladium—alumina, the products of the reaction of but-l-yne with deuterium [189] were but-l-ene, 99.1% frans-but-2-ene, 0.2% cis-but-2-ene, 0.2% n-butane, 0.5%, until at least 75% of the but-l-yne had reacted. But-l-ene hydrogenation and hydroisomerisation were observed to occur when all the but-l-yne had reacted. The formation of but-2-ene as an initial product was postulated as being the result of a slow isomerisation of but-l-yne to absorbed buta-1 2-diene... 

In the rhodium- and platinum-catalysed reactions [167], it is of significant interest that the 7V-profiles calculated from the distributions of deuterium in the n-butane (Table 30) appear to bear no clear relationship to the 7V-profiles of the n-butenes formed simultaneously. This observation has been interpreted as indicating that either the butene which undergoes further hydrogenation never desorbs as butene, or that the sites responsi-... 

The hydroformylation of several olefins in the presence of Co2(CO)8 under high carbon monoxide pressure is reported. (S)-5-Methylheptanal (75%) and (S)-3-ethylhexanal (4.8%) were products from (- -)(S)-4-methyl-2-hexene with optical yields of 94 and 72%, respectively. The main products from ( -)(8)-2,2,5-trimethyl-3-heptene were (S)-3-ethyl-6,6-di-methylheptanal (56.6%) and (R)-4,7,7-trimethyloctanal (41.2%) obtained with optical yields of 74 and 62%, respectively. (R)(S)-3-Ethyl-6,6-dimethylheptanal (3.5% ) and (R)(S)-4,7,7-trimethyloctanal (93.5%) were formed from (R)(S)-3,6,6-trimethyl-l-heptene. (+/S)-l-Phenyl-3-methyl-1-pentene, under oxo conditions, was almost completely hydrogenated to (- -)(S)-l-phenyl-3-methylpentane with 100% optical yield. 3-(Methyl-d3)-l-butene-4-d3 gave 4-(methyl-d3)pentarwl-5-d3 (92%), 2-methyl-3-(methyl-d3)-butanal-4-d3 (3.7%), 3-(methyl-d3)pentanal-2-d2,3-d1 (4.3%) with practically 100% retention of deuterium. The reaction mechanism is discussed on the basis of these results. 

These data have been confirmed further by the results of the investigation of the hydroformylation of 3-(methyl-d3)-l-butene-4-d3 (I) under a high carbon monoxide partial pressure (125 atm) (11) (Scheme 1). 4-(Methyl-d3)pentanal-5-d3 (II) and 2-methyl-3-(methyl-d3)butanal-4-cf3 (III) were obtained in the proportion of 92% and 3.7%, respectively, with almost 100% retention of deuterium in the original position of the chain. 3-(Methyl-(23)pentanal-2-d2,3-(2i (IV) was 4.3% with practically 100% substitution of the hydrogen with deuterium on the tertiary carbon atom of the starting olefin (Scheme 1). These data are consistent with both Casey s and with our data for olefins with quaternary carbon atoms. 

Fig. 11. Deuterium distributions in irons- and ris-2-butenes (a) and in butane (b) formed in the reaction of 1-butene with D2 on MoS2 at room temperature.

It has been suggested previously that the thermal cycloreversion of cyclohexene to ethylene plus buta-1,3-diene proceeds via a vinylcyclobutane intermediate and that, as a consequence, the stereochemistry of deuterium labels on the cyclohexene is not reflected in the deuterated ethenes obtained. This conclusion is supported by results of a study of the stereochemistry of thermal conversion of 1 -viny 1-2.3-r/.v-didcuteriocyclo-butane to butadiene and 1,2-dideuterioethylenes equal amounts of ( )-CHD=CHD and (Z)-CHD=CHD were formed.32... 

Methane produced in the reaction of butane with SbF5-Si02-Al203 did not contain any deuterium when the surface OH groups of the catalyst were replaced by OD. Furthermore, no hydrogen evolution could be detected in these reactions. 

Very recent work (60b) has confirmed that Ir films do not isomerize neopentane most of the transition metals as well as palladium (60c) rearrange isobutane to k-butane but are also inactive for the former conversion. This clearly indicates that isomerization of neopentane on Pt is mechanistically rather special and, in view of the known propensity of Pt to promote ay exchange with deuterium of paraffins (5,49), refocuses attention on the ay species diadsorbed on one metal atom as the precursor for bond shift in simple alkanes. The following mechanism for neopentane isomerization on Pt is feasible, where the shifting... 

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