Organic ions in the gas phase—XXI. Competitive primary loss of C2H4 and CO from 1-tetralone under electron impact

Competing primary reactions by which 1-tetralone loses C₂H₄ and CO give rise to a doublet at mass 118 in the high-resolution mass spectrum corresponding to 96·4% C₈H₆O⁺ and 3·6% C₉H₁₀⁺, respectively. Study of the remainder of the spectrum however, suggests that these intensities constitute a poor measure of the relative importance of the two reaction paths. The C₉H₁₀⁺ ion evidently degrades more readily than C₈H₆O⁺, since an estimated 26% of the ions arising in these paths involve primary loss of CO. This estimate is supported by voltage dependence of the intensity distribution between the members of the doublet. As ionizing voltage is decreased, the intensity distribution is constant to about 20 volts, but between 20 and 10 volts the value for C₉H₁₀⁺ rises smoothly from about 3.5% to about 25%.