The mechanism of elimination of an H2O molecule in desmethylencecalin under electron impact

The mass spectrum of desmethylencecalin has been measured and a fragmentation mechanism for the loss of a water molecule from the [MCH3]+ ion is proposed on the basis of isotope labelling and metastable peak observations. The eliminated water has been shown to involve the carbonyl oxygen and hydrogen atoms of the hydroxyl and acetyl groups.