No 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

The 13C NMR spectra of 35 E‐stilbenols, E‐stilbenyloxyalkanocarboxylic acids and their esters and hydrazides have been calculated and fully assigned. The Ai empirical parameters of the p‐chlorostyryl, p‐bromostyryl, p‐alkoxycarbonylalkoxy, p‐carboxyalkoxy and p‐hydrazinecarbonylalkoxy groups have been calculated for use in the prediction of the chemical shifts of substituted benzenes and stilbenes.