Hydrocarbon films, deuterated

Deuterated hydrocarbon films have been found to be excep-... 

CH CO, NO, SFg co-elute) thick film phase can resolve Ar from Oj at 35 °C deuterated hydrocarbons 350 Same separations as those performed on 5A, but with C, to C., alkanes, alkenes, and alkynes being separated as well 350 Cj to Cg hydrocarbon isomers acetylene in ethylene methane... 

Furthermore, the conformation and orientation of the hydrocarbon chains of MS in the MS-C20 binary and MS-C2o-AL18 ternary systems were investigated by using infrared absorption spectroscopy. In this respect, deuterated arachidic acid (C2o-d) and deuterated n-octadecane AL %-d) were utilized to separate infrared bands due to the hydrocarbon chains of MS from those arising from C2o and AL18. Fig. 26 shows polarized infrared spectra A of 10-layer LB films of pure cadmium arachidate (CdC20), MS-C20- binary and MS-C20-t/-AL18-t/... 

Kemball s work on methane exchange, published in 1951, paved the way for further studies, notably with J. R. Anderson, on the exchange reactions of hydrocarbons and their derivatives on metal films. Much of this work has become classical. He introduced procedures for calculating the yields of deuterated molecules for comparison with experimental results, a methodology which has proved extremely useful in defining the mechanisms of the surface reactions of hydrocarbons. 

Spread films of polylauryl methacrylate (polydodecyl methacrylate) are also susceptible to investigation by neutron reflectometry and partial structure factor analysis because the main chain backbone and dodecyl substituent can be separately deuterated (Reynolds et al. 1995). From such analysis the distribution of dodecyl substituents of backbone segments and water molecules shown in figure 8.19 was obtained. A notable feature of these distributions is that the methacrylate backbone is completely immersed in the sub-phase, in contrast to the arrangement of polymethyl methacrylate. Secondly, the hydrocarbon substituent penetrates deeper into the sub-phase than does the immersed backbone. At first glance this seems most imlikely however, all of this behaviour can be attributed to the dodecyl substituent. Its hydrophobic nature forces the backbone into the sub-phase. To relieve short-range steric interactions between substituents, rotations about main chain bonds force the dodecyl units slightly deeper into the sub-phase before sufficient bonds in the substituent can rotate... 

Within the last few years there has been a growing tendency to draw the analogy between the chemistry of organometallic complexes and that of hydrocarbons adsorbed on metal atoms in surfaces. For example, it is postulated that the isotopic exchan between deuterium and alkanes, catalysed by thin films of nickel, palladium or rhodium, occurs via an equilibrium between a- and 7r-bonded metal-organic species [109, 110, 111, 112]. i-Bonded olefins are postulated in Zie er catalysis, see above, in the catalytic deuteration of aromatic complexes [113], and in a variety of isomerization reactions [112, 114, US]. Other intermediate metal-carbon systems which have been proposed in heterogeneous catalytic systems include carbenes , e.g. M= H2 [109], Ji-enyl systems [114] and of course the metal-carbonyl M—CO and bridging carbonyl M- O—M. 

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