Mass spectrometry of stilbenes: 4′‐Halo‐substituted metameric derivatives of (E)‐stilbenes

Abstract

Owing to the wide use of derivatives of (E)-stilbenes as photosensitizers and in other biological and pharmacological applications, their spectral behaviour has been widely studied. (E)-Stilbene, selected as a model system for studying photochemical reactions and the transmission of substituent effects in aryl groups linked by double bonds, has been the subject of numerous structural investigations.' Substituent effects in the electron impact (E1)-induced mass fragmentation of (E)-stilbene have been the subject of differentWe reported previously on the EI mass spectrometry of 2',4'-dinitro-substituted derivatives of (E)-stilbenes5 and hydroxy-substituted (E)azastilbenes. ' In continuation of studies on the spectral analysis of (E)-4-halostilbenes, our investigations have now been extended to the mass fragmentation of metameric 4halo-substituted ethereal derivatives of (E)-stilbenes, 1-18. H 1 X = C I , R = H 2 X = B r , R = H 3 X = CI, R = CH,COOCH, 4 X = CI, R = CH,COOC,H, 5 X = Br, R = CH,COOCH, 6 X = Br, R = CH,COOC,H, 7 X=CI, R=CH(CH,)COOH, 8 X = CI, R = CH(CH,)COOC,H, 9 X = Br, R = CH(CH,)COOCH, 10 X = Br, R = CH(CH,)COOC,H, 11 X = CI, R = CH,CONHNH, 12 X = CI, R = CH(CH,)CONHNH, 13 X = Br, R = CH,CONHNH, 14 X = Br, R = CH(CH,)CONHNH, 15 X = CI, R = CH,COOH 16 X = CI, R = CH(CH,)COOH 17 X = Br, R = CH,COOH 18 X = Br. R = CH(CH,)COOH

Mass spectrometry of N‐substituted amino acids and their derivatives: Correlation of the abundances of the M+. and selected fragment ions of metamers

“…It should be pointed out that 9,lO-dihydrophenantrene-type structures of the molecule ions a of 1-16 shown in Schemes 1-3 are conjectural, but consistent with previously published literature data.l6sI7 The principal mass fragmentation pathways of N-substituted amino acids (3,6,9,12,15,17,19) are similar to those of their metameric methyl esters (1, 4, 7, 10, 13, 16, 18) and hydrazides (2, 5, 8,11,14) but show differences in the abundances of the important ions.…”

“…The N-substituted 8-phenyl-8-alanines (17,19) may be distinguished from their metameric methyl esters of N-phenylglycines (16,18) on the basis of the highest values of pl and pz .…”

“…the ratio of intensity of the selected fragment ions peaks to that of the parent ion peak. This paper deals with the elucidation of the mass fragmentation of the N-(E)-stilbenyloxyalkylcarbonyl-(or 4'-chlorostilbenyloxyalkylcarbonyl)-substituted derivatives of a-alanine, /?-phenyl-/?-alanine, N-phenylglycine and tryptophan (3,6,9,12,15,17,19) and their metameric methyl esters (1, 4, 7, 10, 13, 16, 18) and hydrazides (2,5,8, 11, 14) (Fig. 1).…”

“…The values of p,-pr calculated from the EI mass spectra recorded at 75 eV (15 eV)P of N-(E)stilbenyloxyalkylcarbonyl-substituted a-alanine (3) and fbphenyl-Palanines (6, 9) and their metameric methyl esters (1, 4, 7) and hydrazides (2, 5, 8) and of N-(E)-stilbenyloxyalkylcarbonylsubstituted tryptophan (12, 15) and their metameric methyl esters (10, 13) and hydrazides(11,14) and of N-(E)-stilbenyloxyalkylcarbonyl-substituted /I-phenyl-/I-alanines(17,19) and their metameric methyl esters(16,18) …”

Electron ionization induced mass spectral study of new metameric N‐(E)‐stilbenyloxyalkylpiperidines, N‐(E)‐stilbenyloxyalkyl‐4‐methylpiperidines and N‐(E)‐stilbenyloxyalkylmorpholines

“…However, the EI fragmentation of their N-(E)-stilbenyloxyalkyl-substituted derivatives has not been reported. The purpose of this investigation was to elucidate the EI fragmentations of 21 new N-(E)-4 0 -stilbenyl-4-oxyalkylsubstituted derivatives of piperidine (1-7), 4-methylpiperidine (8)(9)(10)(11)(12)(13)(14) and morpholine (15)(16)(17)(18)(19)(20)(21), with two to five carbons in a straight alkyl chain ( Fig. 1).…”