Intramolecular electric field effect on a 1J(C,H) NMR spin–spin coupling constant. an experimental and theoretical study
✍ Scribed by Dora G. de Kowalewski; Valdemar J. Kowalewski; Juan E. Peralta; Gernot Eskuche; Rubén H. Contreras; Angel L. Esteban; Maria P. Galache; Ernesto Díez
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 116 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0749-1581
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✦ Synopsis
An experimental study of the e †ects of intramolecular electric Ðelds on 1J(C,H) coupling constants involving a formyl proton in a series of 5-X-salicylaldehydes is reported. The particularly large electric Ðeld component along the bond, calculated for leads to a measured substituent e †ect of 7.36 Hz. For C c wH f X \ NO 2 , other X substituents a linear correlation was found between the calculated substituent electric Ðeld component along the bond and the substituent e †ect on To determine if 5-X substituents a †ect the intramole-
). cular CxOÉ É ÉHwO hydrogen bond, NBO analyses were carried out on and 5-H-salicylaldehyde, and 5-NO 2 they were compared with those corresponding to benzaldehyde and phenol. The e †ects of interactions other than the electrostatic one on couplings were ruled out. The experimental results are in agreement with theoreti-1J(C c ,H f ) cal predictions published previously.