CP/MAS spectroscopy in the determination of the tautomeric forms of gossypol, its Schiff bases and hydrazones in the solid state

✍ Scribed by Piotr Przybylski; Wojciech Schilf; Bohdan Kamienski; Bogumil Brzezinski; Franz Bartl

• Publisher: John Wiley and Sons
• Year: 2008
• Tongue: English
• Weight: 328 KB
• Volume: 46
• Category: Article
• ISSN: 0749-1581
• DOI: 10.1002/mrc.2210

✦ Synopsis

Abstract

New Schiff bases and new hydrazones were synthesized and studied by ^13^C and ^15^N CP/MAS spectroscopy and by ^1^H^1^H COSY, ^1^H^13^C HMBC, ^1^H^13^C HSQC, ^1^H^15^N HMQC and ^1^H^15^N HSQC correlations. The CP/MAS investigation of gossypol has demonstrated that in the solid state it exists exclusively in the aldehyde‐aldehyde tautomeric form. In contrast, CP/MAS studies of hydrazones and Schiff bases reveal that these compounds occur in the solid state in the N‐imine–N‐imine and enamine–enamine tautomeric forms, respectively. It is shown that the ^13^C resonances of C‐6, C‐7 and C‐11 carbon atoms are suitable for distinguishing between the tautomeric forms of aza‐derivatives of gossypol in the solid state. Furthermore, we have proved that the ^15^N CP/MAS spectra can be used to identify these tautomeric forms. Copyright © 2008 John Wiley & Sons, Ltd.