The photochemical reaction of (E,E)-dibenzylidenesuccinic thioanhydride: A spectroscopic and structural study

✍ Scribed by P. Adriaan Davidse; Jan L. M. Dillen

• Book ID: 102846401
• Publisher: John Wiley and Sons
• Year: 1990
• Tongue: English
• Weight: 785 KB
• Volume: 1
• Category: Article
• ISSN: 1042-7163
• DOI: 10.1002/hc.520010402

✦ Synopsis

The first photochromic thioanhydride, (E,E)-2,3-dibenzylidenesuccinic thioanhydride (Ib), was synthesized. Irradiation of (Ib) in benzene, dichloromethane, or chlorofom gives isomerization and cyclization products similar to those obtained for the anhydride analogue (la). The crystal structure of (Ib) was determined (X-rays) and compared to the structures of the anhydride (la) and N-phenylimide (lc). ' H and I3C N M R spectra were recorded, and the electron charge densities of the carbon atoms were calculated with AMI. These results are discussed and compared with those for the compounds la-lc. The thioanhydride (lb) ring is much more twisted than either the anhydride (la) or the imide (lc) rings. The linear relationship between the i3C NMR chemical shifts and the electron charge density on the given atom has been investigated. The C(carbony1) and C(a) carbon atoms of 1 b were found to be greatly deshielded relative to the corresponding atoms in l a and lb. The increase in sensitivity toward cyclization of the thioanhydride (lb) is attributed to the marked change in the charge distribution.