218621-23-9Relevant academic research and scientific papers
Electronic Substituent Effects of Furoxan and Furazan Systems
Fruttero, Roberta,Boschi, Donatella,Fornatto, Elisa,Serafino, Anna,Gasco, Alberto,Exner, Otto
, p. 2545 - 2562 (2007/10/03)
Dissociation constants in 50 percent ethanol were measured for substituted benzoic acids bearing meta and para heterocyclic substituents: 4-methyl-3-furoxanyl, 3-methyl-4-furoxanyl or 4-methyl-3-furazanyl, respectively. 19F NMR spectra of equally substituted fluorobenzenes were recorded in tetrachloromethane. From the data obtained, pK's and substituent induced shifts, the substituent constants (?m, ?p, ?l, ?R) were calculated by standard procedures. All the heterocycles appear as rather strongly electron attracting substituents by inductive mechanism; on the other hand they are very weakly conjugated, sometimes as donors, sometimes as acceptors. The substituent constants are very near for all three systems; presence and position of the exocyclic oxygen has almost no effect on the substituent effect of the whole heterocyclic group.
