1HNMR OF PYRAZOLES: EFFECT OF INTERACTION OF CARBAMOYL GROUP WITH ADJACENT CENTERS ON THE CHEMICAL SHIFTS OF CONCERNED PROTONS

Mohamed, Tarek A.; Youssef, Adel F.; Ahmed, Abd-El-Hamid N.

doi:10.21608/bfsa.1992.70220

1HNMR OF PYRAZOLES: EFFECT OF INTERACTION OF CARBAMOYL GROUP WITH ADJACENT CENTERS ON THE CHEMICAL SHIFTS OF CONCERNED PROTONS

Document Type : Original Article

Authors

¹ Department of Medicinal Pharmaceutical Chemistry, Faculty of Pharmacy, University of Assiut, Assiut 71516, A.R. Egypt

² Department of Organic Pharmaceutical Chemistry, Faculty of Pharmacy, University of Assiut, Assiut 71516, A.R. Egypt

10.21608/bfsa.1992.70220

Abstract

The ¹HNMR of a series of constitutional isomers of dimethylpyrazole carboxamides revealed the contribution of p and/or n-electrons in deshielding protons a- to CONHR group. Intermolecular hydrogen bonding with polar solvent molecules was able to affect more strongly the CONHR proton chemical shift than intramolecular. The observed pattern of d values shown by CONHR proton in the derivative R= C6H11 allowed to assign for it a trans axial conformation. Finally a regression equation was derived to draw a linear relation between the chemical shifts of CONHR protons in both isomers.