ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The analytical potential of negative ion chemical ionization (NICI) mass spectrometry utilizing dibromodifluoro-methane (CF2Br2) and iodomethane (CH3I)/methane (CH4) as reagent gases is examined. The NICI mass spectrum of CF2Br2 contains Br-, [HBr2]- and [CF2Br3]- anions. Weak acids (i.e. those acids with approximately ΔH°(acid) values between 1674 and 1464 kJ mol-1) react with Br- to produce minor yields of the hydrogen-bonded bromide attachment [MH + Br]- anion or are unreactive. Strong acids (i.e. those acids with approximately ΔH°(acid) 〉 1464 kJ mol-1) produce primarily [MH + Br]- anions with a minor yield of proton transfer [M — H]- anion. The NICI spectrum of CH3I/CH4 is dominated by I-. Weak acids react with I- to yield minor amounts of [MH + 1]- or are unreactive. Strong acids produce only [MH + l]- anions. From a consideration of the gas-phase basicity of the halide anion and the binding energy of the hydrogen-bonded halide attachment adduct, thermochemical data are used as a potential guide to rationalize or predict the ions observed in NICI mass spectra.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210240103
Permalink