Ethane and Higher Linear Alkanes

Apparent Arrhenius Parameters ( , in A), Rates at 423 K Parameters (M) for Exchange of Ethane with Deuterium on Metals of Groups 8 to 10 

There is a readier means of achieving multiple exchange with ethane than the methane this involves the repeated inter-conversion of ethyl radicals with ethane, thus  

Deuteroethane distributions have been interpreted in terms of a parameter P, which is the quotient of the rate constants for ethyl to ethene and ethyl reverting to ethane. For molybdenum, tantalum, rhodium and palladium films, a single value of P (respectively 0.25, 0.25, 18 and 28) sufficed to reproduce the observed distribution, assuming that a further deuterium atom is acquired at every opportunity. With other metals, however, two simultaneous values of P appeared to operate, one contributing 30 to 50% of the reaction having a high P value (13.5-18) and another having a much lower P value (0.36-2). This analysis has not however been accorded an interpretation in terms of the metals physical properties or of ensemble sizes and structures responsible for each participant. 

It has long been a goal of research on alkane exchange to identify isomers of the same mass, e.g. ethane-l - i2 (CH3-CHD2) and ethane-l,2-rf2 (CH2D-CH2D) this has at last been accomplished by NMR of C-containing ethane, and the 

TABLE 6.3. Analysis of the Products of Reacting C-Labelled Ethane with Deuterium on Platinum Foil at 675 K Pd/Pe = 10) 

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