Mercaptans catalyst inhibitors

Many nucleophiles act as inhibitors of platinum, palladium and rhodium catalysts. The strongest are mercaptans, sulfides, cyanide and iodide weaker are ammonia, azides, acetates and alkalis [26]. 

The remarkable growth of interest in polarographic applications among polymer chemists can be easily understood, because the polarographic methods enable one to follow the analysis of monomers, of catalysts (both initiators and inhibitors) and even certain reactive groupings in polymers. Several compounds belonging to the first two classes, e.g. halogenated-ethylenes, 1,2-diaminocyclohexane in hexamethylenediamine, butadiene, styrene, vinylacetate, mercaptans and peroxides have already been discussed in Chapter VI. As in other sections of this Chapter, several other examples are now mentioned. 

Oxidation Processes. These processes convert mercaptans into less odoriferous disulfides by such processes as the doctor, copper chloride, hypochlorite, and lead sulfide, processes. Since disulfides harm the lead susceptibility of gasoline and since the need of reduction of mercaptans to doctor sweet (0.0004 per cent) is being questioned, these processes are being gradually abandoned. However, catalysts or inhibitors of the 7>-phenylenediamine type, which in the presence of air cause mercaptans in some caustic-washed gasolines to be converted during a few days into disulfides (so-called inhibitor sweetening), continue to be used because of the cheapness of such a process. Small amounts of... 

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