Methanol deuterium exchange over platinum

The exchange of deuterium gas with acetic acid over Adams platinum catalyst and the effect of nitro compounds 7,8) on this exchange have been investigated and the effects of these nitro compounds on the exchange correlated with their respective hydrogenation kinetics (5). An extension of exchange studies to methanol and deuterium gas over Adams platinum catalyst was undertaken. 

The Exchange of Deuterium with Methanol over Adams Platinum Catalyst and the Effect of Certain Nitro Compounds Upon the Rate of This Exchange... 

Deuterium gas exchanges rapidly with methanol over Adams platinum catalyst at 35 . The influence of catalyst weight and treatment and of deuterium pressure on this exchange have been studied, as well as the effects of several aromatic, aliphatic, and olefinic nitro and related compounds. All of these nitro compounds reduce the rate of the exchange reaction initially, and the magnitude of such reduction increases with increasing specific rate constant for the platinum catalyzed hydrogenation of these compounds. 

Although the exchange of the hydroxyl hydrogen in methanol with deuterium in various deuterium compounds such as deuterium oxide and deuterium sulfide has been reported 1-3) and the preparation of methanol-d (CH3OD) by the saponification of esters and decomposition of Grignard reagent with deuterium oxide has been described 4 6), the catalytic exchange of deuterium gas with methanol over Adams platinum catalyst has not been previously studied. 

Table II shows the effect of catalyst weight upon the rate of exchange of deuterium with methanol over prereduced and washed Adams platinum catalyst. The rate of exchange at both 300 and 500 c.p.m. shaker rate is the same. Three washes of the pre-reduced catalyst with purified methanol gave...

The Effect of Catalyst Weight upon the Rate of Exchange of Deuterium with Methanol over Pre-reduced and Washed Adams Platinum Catalyst... 

Fig. 1. The effect of various nitro compounds upon the rate of exchange of deuterium with methanol over 2.0 mg. of Adams platinum catalyst, pre-reduced and washed. A, methyl ethyl ketoxime B, nitroethane C, nitromesitylene D, aniline E, befa-nitrostyrene F, nitrobenzene G, 2-nitro-l-butene.

In any of these systems, the methanol exchange and reduction of the nitro or unsaturated compound, as evidenced by absorption of deuterium, are competitive reactions. The kinetics of hydrogenation of these nitro compounds in ethanol over Adams platinum catalyst are similar, being zero order in acceptor and first order in hydrogen pressure (IS). The aromatic and conjugated olefinic nitro compounds have much higher specific rate... 

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