Propylene deuterated

Many research groups have attributed the isomerization to a series of additions and eliminations of a cobalt carbonyl hydride. However, it has been shown that aldehydes may be found with formyl groups attached to a carbon atom other than the two of the double bond even under non-isomerizing conditions. Piacenti and co-workers (44, 45) studied the hydroformylation of [l-14C]propylene and of a>-deuterated a-olefins. Even for a-olefins with chain lengths up to C6, the formyl group was attached to all possible carbon atoms in the product mixture. However, in the deuterated experiments, deuterium was present only on carbons 2, 3, and a) of the resulting aldehydes. These results were explained by pro-... 

The fact that Schrock s proposed metallocyclobutanes decomposed to propylene derivatives rather than cyclopropanes was fortunate in that further information resulted regarding the stereochemistry of the olefin reaction with the carbene carbon, as now the /3-carbon from the metal-locycle precursor retained its identity. The reaction course was consistent with nucleophilic attack of the carbene carbon on the complexed olefin, despite potential steric hindrance from the bulky carbene. Decomposition via pathways f-h in Eq. (26) was clearly confirmed in studies utilizing deuterated olefins (67). 

The propylene oxide complex not only dissociated into its components but also transformed to either an oligomer or a polymer of propylene oxide when it was allowed to stand in solution. This transformation could be followed by H-NMR techniques with the use of a-deuterated propylene oxide instead of the non-deuterated one. Its rate depended on the nature of solvent and on the temperature. This experimental result implies that the monomer liberated by dessociation of the complex is polymerized by the catalyst, that only a minute fraction of the organozinc component of the complex actually acts as a catalyst for polymerization, and that the rate of propagation is far faster than that of initiation. These implications together with the evidence that coordination of the monomer to the catalyst is a prerequisite for the stereospecific polymerization led us to the detailed studies of the bulk polymerization, that is, the polymerization of propylene oxide in propylene oxide solution. 

Oguni,N., Fujita,T., Tani.H. Stereospecific polymerization of propylene oxide and its a-deuterated derivative by bis(ethylzinc) t-butylamine in the presence of water as a catalyst (in preparation). 

NMR studies of polymers made with deuterated monomers provide additional information on the cyclic isotactic transition state. Miyazawa and Ideyuchi (97) have shown that the isotactic polymerization of propylene takes place with cis opening of the olefinic double bond. This shows that the 4-membered cyclic transition occurs with reaction of the new monomer on the front side of the propagating ion as illustrated in Fig. 12. 

The use of isotopic tracers has demonstrated that the selective oxidation of propylene proceeds via the formation of a symmetrical allyl species. Probably the most convincing evidence is presented by the isotopic tracer studies utilizing, 4C-labeled propylene and deuterated propylene. Adams and Jennings 14, 15) studied the oxidation of propylene at 450°C over bismuth molybdate and cuprous oxide catalysts. The reactant propylene was labeled with deuterium in various positions. They analyzed their results in terms of a kinetic isotope effect, which is defined by the probability of a deuterium atom being abstracted relative to that of a hydrogen atom. Letting z = kD/kH represent this relative discrimination probability, the reaction paths shown in Fig. 1 were found to be applicable to the oxidation of 1—C3He—3d and 1—QH —1 d. 

The value of z was calculated from the distribution of deuterium and acrolein and found to be very close to the theoretical value. It was also noted that the distribution of deuterium in acrolein was the same regardless of which deuterated propylene was used as the starting material and that the deuterium was found only on the terminal carbon atoms of the product acrolein. 

To test this hypothesis, propylene was oxidized on a deuterated catalyst surface. The ir-allyl route would yield acrolein containing no deuter-... 

The binding of alkenes to transition metals, to form n complexes or r 2 complexes or metallacyclopropanes, is a Lewis acid-Lewis base interaction that is made more elaborate by back bonding from the metal to the alkene. There are many examples of deuterium IEs on complexation. One that was studied extensively is the binding of ethylene, propylene, and 2-butene to Ag+, where the deuterated alkene binds more strongly.88 For example, Acd,=cd,/Ac[ i, [Pg.145]

The reaction of propylene on ZrC>2 exhibits the same characteristics as on other oxides. Propane-d2, for example, is selectively formed in the deuteration process, with no hydrogen exchange in propylene215. New features appear, however, when zirconia is dispersed on other oxides (alumina, silica, titania)215,216. A considerable rate increase is observed and exchange in propylene proceeds simultaneously with addition via the associative mechanism through the common intermediate n-propyl and s-propyl species. 

Reaction of H2 (40 psi, 25°C, pentane) with (C5Me4R)Ta(propylene)Cl2 produces a green diamagnetic material of stoichiometry [(C5Me4R)Ta(H)Cl2]2 (XL) showing v (infrared) at 1585 cm-1, which moves to 1150 cm-1 upon deuteration, and which is presumably iva-H-... 

In a recent investigation along the same lines, Graessley and coworkers [8] used a series of asymmetric three-arm poly(ethylene-aZt-propylene) stars, obtained by hydrogenation or deuteration of the corresponding asymmetric po-... 

Figure 13.6 Decrease in 13C NMR signal intensity ( ) and soluble polymer fraction ( ) for crosslinked EPR containing 36 mol% propylene, as a function of radiation dose [110]. The NMR experiments were conducted in deuterated chloroform at 25 °C The solid lines are drawn as a guide to the eye...

Silica hydrolysis-condensation of alkoxysilane-terminated chains of various polymers (PB, poly(propylene)-glycol, poly (ethylene)-glycol) leads to the formation of silica nodules. Hybrid (organic-inorganic) nanocomposite rubbery materials are obtained in this way. These materials have been swollen by various deuterated solvents, in order to probe the order induced in the polymer matrix under stress [80]. 

It should also be mentioned that atactic polymers may be formed from monodeuteropropylene and pentadeuteropropylene, similarly to the case of the polymerisation of non-deuterated propylene. However, atactic structures with respect to one stereogenic tertiary carbon atom, with the other possibly arranged to form tactic polymer sequences, are not known. Also, ditactic polymers, which might be characterised by the appearance of two distinct series of tacticity as regards both stereogenic tertiary carbon atoms, i.e. the isotactic with respect to one stereogenic carbon atom and syndiotactic with respect to the other one, and vice versa, are not known. 

It should be indicated that the methylacetylene and propylene " are more complex reactants than the nonsubstituted counterparts and depict nonequivalent hydrogen atoms at the acetylenic and methyl group (methylacetylene) and at the vinyl and methyl group (propylene). Therefore, even the detection of the atomic hydrogen loss makes it difficult to elucidate if the hydrogen atoms are lost from the methyl group, the acetylenic/vinyl units, or from both positions. In these cases, it is very useful to conduct experiments with partially deuterated reactants J3-... 

Here, the phenyl radical once again attacks the unsamrated bond. However, the steric effect and larger cone of acceptance (the methyl group screens the p carbon atom and makes it less accessible to addition) direct the addition process of the radical center of the phenyl radical to the a carbon atoms of methylacetylene and propylene (the carbon atom holding the acetylenic hydrogen atom). Consequently, crossed beam reactions with complex hydrocarbon molecules can be conducted and valuable information on the reaction pathways can be derived if (partially) deuterated reactions are utilized. 

Katzer (28) observed that counterdiffusion of benzene and cumene within the pores of H-mordenite does not occur at low temperatures. However, H-mordenite shows activity for the alkylation of benzene with propylene to form cumene under the liquid phase conditions used for the diffusion studies, and he has suggested that reaction must occur on the external crystallite surface, or just within the pore mouth. In earlier studies on the isomerization of 2,3-dimethylbutene-l at 0°-20°C over a deuterated Y-type faujasite (62), we observed that the extent of isomerization (2,3-dimethylbutene-2) was far greater than the extent of deutera-tion only a fraction of the total deuterium on catalyst OD groups was exchanged. One possible explanation—assuming a protonic isomerization mechanism—is that, because of lowered intracrystalline diffusion rates... 

PI)2(dPBd)2 stars were also prepared by the method developed by Iatrou and Hadjichristidis,95 using deuterated butadiene. The final products were then hydrogenated, the PI arms being transformed to polyethylene- ///-propylene) and the dPBd arms to partially deuterated polyethylene. 

The exact mechanism of propylene glow discharge polymerization is not known. The presence of a terminal acetylene (presumable propyne) in the gaseous products of propylene polymerization was indicated by the interaction of the cold trap gaseous condensates with 1% alcoholic or ammonlacal AgNO sol.(22) after the polymerization was over. An immediate formation of an explosive silver acetyllde was detected. Intermediate formation of propyne is also indicated by the IR spectra of the yellow relatively less volatile liquid left in the cold trap after the polymerization was over. Sharp but weak absorptions at 3310 cm l and 1270 cm are indications of a substituted acetylenic compound. The IR spectra of the yellow liquid also points to the presence of mono, dl- and trl-substituted aromatic compounds in the mixture (i.e. sharp absorption bands at 3080 cm l, 1640 cm l, 920 cm , 810 cm and a multiple band in the 1000-1120 cm l region are observed). The NMR spectra in deuterated acetone indicated the presence of an aromatic nucleus in the yellow liquid obtained from the cold trap. The formation of aromatic compounds can be explained if a propynyllc Intermediate is involved. 

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