ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The mass spectra of 4-methyl-7-coumarinyl and 7-coumarinyl diestes ROOC(CH2)nCOOR (n = 2-12) have ben studied by appearance potential measurements, deuterium labelling and by comparison with suitable reference compounds such as the mised diestes ROOC(CH2)nCOOR′ (R=4-methyl-7-coumarinyl and R′ = methyl and phenyl) and 3.4-dihydro-4-methyl-coumarinyl diestes. Observations on the fragment ions of m/e 324, produced from the 7-coumrinyl diestes and their photocyclomers, by elimination of the central bridge as O=C=CH—(CH2)n-2—CH=C=O, demonstrate the existence and reversible formation of cyclomeric molecular ions. A stable bound system between the coumrin end groups is formed only at high internal energies by expulsion of a hydrogen atom, followed by elimination of the central bridge from the [M—H]+ ion. It is also shown that the lifetime of the open form molecular ions decreases remarkably for chain lengths with n larger than 6.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210120410
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