MASS AND MICROWAVE SPECTROSCOPIC STUDIES OF PYROLYSIS OF CHLOROACETALDEHYDE AND ITS METHYL-DERIVATIVES

The pyrolysates of chloroacetaldehyde and its methyl derivatives have been investigated by pyrolysis-mass spectrometry and microwave spectro scopy. Ketene was generated by dehydrochlorination of chloroacetaldehy de. Ketene and s-trans-acrolein were produced by the elimination of me thyl chloride and by dehydrochlorination from 1- and 2-chloropropional dehyde respectively. These facts indicate that the pyrolysis mechanism s of the precursors differ according to the position of the methyl gro up substituted. Methyl vinyl ketone observed from 3-chloro-2-butanone suggests that the dehydrochlorination is more dominant than the elimin ation of methyl chloride observed in 1-chloropropionaldehyde, and that this mechanism is quite similar to that for 2-chloropropionaldehyde. Moreover, some interesting pyrolysates, such as acetaldehyde and methy l chloride, were generated from chloroacetaldehyde, vinyl chloride fro m 1-chloro-propionaldehyde, and methyl acetylene and propene from 3-ch loro-2-butanone. As these pyrolysates, with the exception of acetaldeh yde, do not include oxygen, their pyrolysis mechanisms can not be expl ained without the elimination of carbon monoxide.