Carbon monoxide proton release

In addition to catalyzing hydroformylation, the platinum SPO complexes are excellent hydrogenation catalysts for aldehydes (as already demonstrated by the side products of hydroformylation), in particular, in the absence of carbon monoxide. Further, in ibis process, the facile heterolytic splitting of dihydrogen may play a role. The hydrogenation of aldehydes requires the presence of carboxylic acids, and perhaps the release of alkoxides from platinum requires a more reactive proton donor than that available on the nearby SPO. For example, 4 hydrogenates 2-methylpropanal at 95 °C and 40 bar of H2 to give the alcohol, with a TOF of 9000 mol moN h (71). 

Methanol is protonated to give an ion pair with a ruthenium carbonyl iodide anion. Dehydration by an 5 2 type process gives a methyl complex which undergoes insertion of carbon monoxide to an acetyl intermediate followed by reduction to an alkoxy derivative. Finafly. ethanol is released via hydrogenation of the alkoxy intermediate. 

The dissociation behavior of the protonated molecule of pethidine (Fig. 4.3,4) was significantly different and yielded less but still informative product ions that characterize the synthetic opioid (Fig. 4.4b). ° The precursor ion at m/z 248 was predominantly de-esterified by the elimination of ethylene (-28 Da) to yield the ion at m/z 220, which subsequently released carbon dioxide ( 4 Da) or water (-18 Da) and carbon monoxide (-28 Da) to produce m/z 176 and 174, respectively. The consecutive losses resulting in the product ion at m/z 174 were... 

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