ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Based on the quasi-equilibrium theory of mass spectra it is shown that the intensity ratio [A]+/[M]+, where [A]+ is a fragment ion and [M]+ is the molecular ion, is given by [A]+/[M]+ = f′ (k1/kt) ((1/f) - 1), where f is the fraction of molecular ions with insufficient energy to fragment, f′ is the fraction of [A]+ ions with insufficient energy to fragment, and k1/kt is the fraction of fragmenting molecular ions which form [A]+. For substituted acetophenones it is shown that f depends on the substituent present and that f′ k1/kt is also substituent dependent for formation of both [CH3CO]+ and [YC6H4CO]+. It is also shown that no direct information concerning the effect of a substituent on the rate of a particular fragmentation reaction can be obtained from intensity studies.The ionization potentials of the parent molecules and the appearance potentials of the [YC6H4CO]+ fragment ions have been measured for fifteen substituted acetophenones and the correlations with substituent constants are discussed.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210021106
