Mass spectrometry carbon monoxide, loss

Mass spectral fragmentation patterns of alkyl and phenyl hydantoins have been investigated by means of labeling techniques (28—30), and similar studies have also been carried out for thiohydantoins (31,32). In all cases, breakdown of the hydantoin ring occurs by a-ftssion at C-4 with concomitant loss of carbon monoxide and an isocyanate molecule. In the case of aryl derivatives, the ease of formation of Ar—NCO is related to the electronic properties of the aryl ring substituents (33). Mass spectrometry has been used for identification of the phenylthiohydantoin derivatives formed from amino acids during peptide sequence determination by the Edman method (34). 

An immense amount of mass spectral data is available on more complex coumarins. Reviews have appeared on the mass spectrometry of furocoumarins and pyranocoumarins (B-71MS139,75RCR603), many analogues of which occur naturally. The pyranocoumarin (127) is of interest since it fragments with four successive losses of carbon monoxide <66JCS(C)1712). 

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