ISSN:
0030-493X
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The 12.1 eV, 75°C electron impact mass spectra of 24 urethanes, RNHCO2C2H5 [R = H, C2H2n +1 (n = 1-8), CH2=CHCH2, Ph, PhCH2 and PhCH2CH2], and seven symmetrically disubstituted urethanes R2NCO2C2H5 (R = Cn H2n + 1 (n = 1-4)) are reported and discussed. All 31 spectra show appreciable molecular ion peaks. For n -Cn H2n +1 NHCO2C2H5, M+ · usually is the most abundant ion in the spectrum. A peak at m/z 102 of comparable intensity also is present; this corresponds to formal cleavage of the bond connecting the α- and β-carbon atoms in the N-alkyl group, though it is unlikely that the daughter ion has the structure [CH2=NHCO2C2H5]+. In the RNHCO2C2H5 series, branching at the α-carbon atom enhances the relative abundance of the ion arising by notional α-cleavage at the expense of that of M+ ·. Formal cleavage of the bond between β- and γ-carbon atoms occurs to some extent for [RNHCO2C2H5]+· ions; this reaction provides information on the degree of branching at the β-carbon, especially if metastable molecular ions are considered. The higher n-CnH2n +1NHCO2C2H5 (n = 5-8) urethanes exhibit two other significant ions in their mass spectra. First, there is a peak at [M — C2H5]+. Secondly, a peak is present at m/z 90; the most plausible structure for this ion is [H2N(HO)COC2H5]+, arising by double hydrogen transfer from the alkyl group and expulsion of a [CnH2n -1]· radical. Ions originating from secondary decomposition of the primary ionic species are generally of only very low abundance in these spectra.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/oms.1210240210
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