Solvent-induced shifts in NMR spectroscopy by a combination of benzene and trifluoroacetic acid as an aid to the structure elucidation of isoflavones

✍ Scribed by Hirday N. Jha; Virinder S. Parmar

• Publisher: Elsevier Science
• Year: 1983
• Tongue: English
• Weight: 233 KB
• Volume: 39
• Category: Article
• ISSN: 1386-1425
• DOI: 10.1016/0584-8539(83)80041-5

✦ Synopsis

We have observed that the benzene-induced solvent shifts ofcertain methoxyl groups in the NMR spectra of isoflavones are appreciably changed by the addition of a small amount of trifluoroacetic acid to the solution of the isoflavones in a 1: 1 mixture of chloroform and benzene. The methoxyl group at position C-5 can be differentiated from that at position C-7 and also this shift value can help in identifying methoxyl group at 2' position in 2-methylisoflavones.

Based upon steric and electronic factors, the explanations for these shifts have been suggested.