Benzo thiophene derivatives spectra

There has been no systematic study of the spectra (mass, UV, IR, or NMR) of benzo[c]thiophene derivatives, although spectroscopic data have been recorded for individual compounds in the more recent literature. The spectroscopic data for benzo[c]thiophene itself have been recorded,5,6,12,15,16 the IR spectrum of l,3-diphenylbenzo[c]-thiophene has been studied in some detail,17 and the excitation and... 

When a cyclization reaction leads to mixtures of two isomeric benzo[6]thiophenes, their relative proportions are readily estimated by examination of the 1H NMR spectrum of the mixture.96 104-106 Mixtures obtained by acetylation98 and bromination 76,90 reactions and by Baeyer-Villiger oxidation of acetylbenzo[6]thiophenes107 have been similarly analyzed. The 19F NMR spectra of several polyfluoro-benzo[6]thiophenes have been examined,103,108-m and used to study the reaction of 4,5,6,7-tetrafluorobenzo[6]thiophene with nucleophiles.108 The tautomerism of 2-amino-,112-114 3-N-phenylamino-,116 and 3-hydroxybenzo[6]thiophene109,116-117 derivatives has been studied by 7H NMR spectroscopy. 

The main features of the mass spectrum of benzo[6]thiophene have been established by Porter,121 using the spectrum of 3-deutero-benzo[6]thiophene for comparison purposes. Triply charged ions have been detected in the mass spectra of benzo[6]thiophene and its 2- and 3-methyl derivatives.126... 

The mass spectra of 2-phenyl-, 3-phenyl-, and 3-methyl-2-phenyl-benzo[6]thiophene have been discussed, and tentative structural assignments of the main fragment ions have been made.121 The mass spectra of benzo[6]thiophene-l, 1-dioxide and its 2,3-dihydro derivative have been examined in detail.121> 127 The partial mass spectrum of 2,3-dihydrobenzo[6]thiophene has been recorded.124... 

Attempts to correlate the position of the substituent with the UV spectrum have been largely unsuccessful, but some general comments may be made. The spectra of most monosubstituted derivatives resemble that of benzo [6]thiophene and the three distinct zones usually remain. Methyl or halo substituents cause an overall bathochromic shift relative to benzo [6]thiophene—zone B is most affected by 3-, 5-, or 6-substituents zone C by 5-substituents.134,159,162 3-Alkyl-benzo[6]thiophenes are characterized by zone-B bands of lower intensity than those of benzo [6]thiophene and its other alkyl derivatives.134 The UV spectra of 2-methylbenzo[6]thiophene and its selenium analog have been compared.182... 

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