Ethylenes, deuterated

Ethylene Ha Deuterated ethylenes Deuterated ethanes Olefin exchange... 

Ethylene, deuterated by DSC Single Tm varying smootiily with composition and no gross segregation occurred English etal. (1985)... 

Fig. XI-7. Volume fraction profile of 280,000-molecular-weight poly(ethylene oxide) adsorbed onto deuterated polystyrene latex at a surface density of 1.21 mg/m and suspended in D2O, from Ref. 70.

Deuteration at C-3 by Lithium Aluminum Deuteride Reduction of 5a.-Pregnane-3,20-dione 3-Tosylhydrazone 20-Ethylene keta ... 

Deuteration at C-3 by lithium aluminum deuteride reduction of 5a-pregnane-3, 20-dione 3-tosylhydrazone 20-ethylene ketal, 177... 

Deuteration at C-12 by desulfurization of 12-thioketals with Raney Nickel preparation of the ethylene thioketal, 172 desulfurization of the mercaptal, 173... 

The most famous mechanism, namely Cossets mechanism, in which the alkene inserts itself directly into the metal-carbon bond (Eq. 5), has been proposed, based on the kinetic study [134-136], This mechanism involves the intermediacy of ethylene coordinated to a metal-alkyl center and the following insertion of ethylene into the metal-carbon bond via a four-centered transition state. The olefin coordination to such a catalytically active metal center in this intermediate must be weak so that the olefin can readily insert itself into the M-C bond without forming any meta-stable intermediate. Similar alkyl-olefin complexes such as Cp2NbR( /2-ethylene) have been easily isolated and found not to be the active catalyst precursor of polymerization [31-33, 137]. In support of this, theoretical calculations recently showed the presence of a weakly ethylene-coordinated intermediate (vide infra) [12,13]. The stereochemistry of ethylene insertion was definitely shown to be cis by the evidence that the polymerization of cis- and trans-dideutero-ethylene afforded stereoselectively deuterated polyethylenes [138]. 

Similar experiments were done at several temperatures starting with either normal or fully deuterated ethylene chemisorbed on... 

We have measured the kinetics of ethylidyne formation from chemisorbed ethylene over Pt(lll) surfaces. The rates of reaction display a first order dependence on the ethylene coverage. There is an isotope effect, since the reaction for CjH is about twice as fast as for CjD. We obtain values for the activation energy of 15.0 and 16.7 Kcal/mole for the normal and deuterated ethylene, respectively. These values are lower than those obtained from TDS experiments, but the differences can be reconciled by taking into account the hydrogen recombination when analyzing the thermal desorption data. 

Selectively deuterated 1-aminocyclopropanecarboxylic acid ACC 71 was prepared to investigate the biosynthesis of ethylene in plants [105 a] and of ammonia and 2-ketobutyrate in Pseudomonas [105bj. 

Anomalous behavior is exhibited by the tricarbonylruthenium complex of 1-methoxycar-bonyl-1//-azepine in that at room temperature with TCNE, perfluoropropanone or l,l-dicyano-2,2-bis(trifluoromethyl)ethylene, exo-2,5-adducts, e.g. (143), are obtained. Deuteration studies reveal that the addition is non-concerted and involves an initial electrophilic attack by the 2u--system at the uncoordinated double bond of the azepine-metal carbonyl complex <77JCS(D)204). 

An alternative explanation by Schrauzer and collaborators138,139 assumes mononuclear vanadium(II) as a two-electron reductant dinitrogen would be reduced in a first step to N2 . N2 and hydrazine would be obtained by disproportionation of N2H2 (diazene), inside the Mg(OH)2 lattice, which would protect the diazene from rapid decomposition to the elements. On reducing acetylene in deuterated media, the resulting ethylene was exclusively cis.139... 

As the reaction proceeds, the ethylene becomes progressively more deuter-ated [Fig. 11(b)] and this is reflected in a progressive growth of the more heavily deuterated ethanes in the latter stages of the reaction. These conclusions are in general agreement with those subsequently obtained for the reaction over nickel films [102] (see Table 7). 

Irradiation of asingle crystal of deuterated and undeuterated 6-methyl-l,2,4-triazine-3,5-dione (13) with y- or X-rays afforded radicals, the EPR spectra of which were recorded by Horak and Schoffa (71MI21901). The 19-line spectrum of the deuterated radical indicates interaction of the unpaired electron with two equivalent protons, and two non-equivalent nitrogen atoms. The EPR spectra of metastable triplet states of 6-methyl-l,2,4-triazine-3,5-dione (12) in ethylene glycol/water glass at -196 °C were recorded by Shulman and Rahn (66JCP(45)2940). It was found that the lowest triplet state is a 7r- 7r state. 

The major pathways for the fragmentation of kojic acid (81,5-hydroxy-2-hydroxymethyl-pyran-4-one), are shown in Scheme 14 support for each route was provided by the appearance of metastable ion peaks (67MI22203). An RDA cleavage followed by loss of a CH2OH radical produces ion (81a), m/e 69, the structure of which was substantiated by deuteration experiments. The ion at m/e 97 arises by extrusion of CO from the molecular ion and loss of HO- from the side chain structures (81b) and (81c) were proposed. Decomposition of [M]t occurs to give ethylene and an HC=0 fragment. The initial stage involves loss of a -CHO radical from the hydroxymethyl substituent, a process which has... 

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