Deuterium with hydrocarbon solvent

The formation of the dicyclopropylmercury alone or in combination with the adsorbed radical type intermediates accounts for the observation that the substrate disappears at a faster rate than the reduction product appears The dicyclopropylmercury can then accept an electron to produce the anion and a cyclopropylmercury radical which in combination with the mercury surface becomes an adsorbed radical (equation 7) which can be recycled through the pathway of equation 5 or equation 6. The anions formed in equation 3, equation 5, and equation 7 react at the surface with acetonitrile solvent (equation 8) to yield the hydrocarbon. When deuterated acetonitrile was used the hydrocarbon isolated contained 76% deuterium The anion can also react with the electrolyte, tetraethylammonium bromide, in an elimination reaction (equation 9) to produce hydrocarbon, ethylene and triethylamine, all of which have been identified in the reaction mixture ... 

A very different neutrally charged complex for alkane activation has been reported recently and is shown in Scheme 34(A). The compound is a hydridoplatinum(II) complex bearing an anionic ligand based on the familiar nacnac-type, but with a pendant olefin moiety (97).This complex is extremely soluble in arenes and alkanes and activates C-H bonds in both types of hydrocarbons. This is indicated by deuterium incorporation from deuterated hydrocarbon into the substituents on the arene of the ligand and into the Pt hydride position (A A-d27, Scheme 34). The open site needed for hydrocarbon coordination at Pt(II) is created by olefin insertion instead of anion or solvent substitution (97). 

Hydrogen-deuterium exchange in alkanes shows the same dependence on the composition of solvent, and concentration of mineral acid, of platinum( 11) and of chloride ions as does the exchange in aromatic hydrocarbons. The dependence of the exchange rate on solvent composition has been discussed in Section III,B,1. The rate is independent of mineral acid concentration, increases nonlinearly with increase in the concentration of platinum 11), and decreases nonlinearly with increase in the concentration of chloride ions (55). The nonlinear dependences are due to the solvolysis of the PtCL,2- ion ... 

The rate of hydrogen exchange depends on the protolytic properties of both the solvent and the substrate. In fact there is a correspondence between the magnitude of the rate constants for deuterium exchange with ND3 and the conventional ionization constants of hydrocarbons which were used by Conant and Wheland (1932) and by McEwen (1936) to obtain the first quantitative estimates of the acidity of hydrocarbons. To do this, they determined the equilibrium of metallation of hydrocarbons by organo-alkali metal compounds. This reaction was described by Shorygin (1910) and is represented by the equation... 

IR spectroscopy becomes even more easy to use for identification of various fulleranes if deuterium is used instead of hydrogen. Experiments with deuterisation of C60 proved that it occurs in the same way as with hydrogen (Tarasov et al. 2001 Shulga et al. 2003). However, using deuterium allows to identify peaks due to C-D bonds of fulleranes clearly distinctly from any contamination hydrocarbons which are typically found in almost any fullerene sample due to presence of solvent traces etc. 

Further confirmation of the surface nature of Grignard formation is the observation that when THF-ds and diethyl ether-djo were used as solvent only 28% and 6% deuterium, respectively, were found in the hydrocarbon fraction of the reaction . The source of hydrogen atoms is the disproportionation of the surface radicals. Moreover, the yield of hydrocarbons from reaction in THF is only 1.0-1.5 % whereas in diethyl ether the yield is 20%. This is in accord with the greater solvating power of THF which removes the metal organic species from the surface of the magnesium. Recent XPS analysis of the Grignard formation reaction is consistent with the surface nature of the reaction . 

The details of the mechanism of decay of states in alkanes retain their interest. The effect of deuterium on fluorescence lifetimes has been discussed in terms of the theory of radiationless transitions. Analysis of fluorescence line shapes and Raman excitation profiles of tetradesmethyl-p-carotene in isopentane has been carried out at 190 and 230K . Solvation occurs over a time scale of about 100 fs whilst vibrational relaxation has a time scale of about 250 fs. The kinetics of the interaction of alcohols with the excited state of triethylamine shows involvement of a charge transfer exciplex . Ionizing radiation is a means of exciting saturated hydrocarbons and the complexity of three component systems containing saturated hydrocarbons, aromatic solvent, and fluorescent solute has been examined. ... 

When monodeuterated methanol Me-OD was used as solvent hydrocarbon (R)-( —)-2 was formed, with more than 95% deuterium incorporation in the 1-position. 

When the acidities of hydrocarbons are compared in terms of the relative stabilities of neutral and anionic forms, the appropriate data are equilibrium acidity measurements, which relate directly to the relative stability of the neutral and anionic species. For compounds with pA > 35, it is difficult to obtain equilibrium data. In such cases, it may be possible to compare the rates of deprotonation, i.e., the kinetic acidity. These comparisons can be made between different protons in the same compound or between two different compounds by following an isotopic exchange. In the presence of a deuterated solvent, the rate of incorporation of deuterium is a measure of the rate of carbanion formation. Tritium ( H)-NMR spectroscopy is also a sensitive method for direct measurement of kinetic acidity. ... 

Isomerization most commonly proceeds according to the first two mechanisms. The carbene mechanism was proposed for the isomerization of 1-alkenes in the presence of [Pd2Cl6] in acetic acid. In the products of isomerization of 3- /2-1-octene with the application of this catalyst neither migration of deuterium to the terminal carbon atom nor deuterium transfer from the solvent to the hydrocarbon was observed which support the carbene mechanism. The absence of deuterium at the first carbon excludes 1,3-hydrogen migration and therefore the 71-allyl mechanism. The fact that there is no deuterium transfer from the solvent to the olefin indicates that the formation of hydrido complexes involving the solvent also does not take place, which eliminates the first... 

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