1HNMR OF PYRAZOLES: EFFECT OF INTERACTION OF CARBAMOYL GROUP WITH ADJACENT CENTERS ON THE CHEMICAL SHIFTS OF CONCERNED PROTONS | ||||
Bulletin of Pharmaceutical Sciences Assiut University | ||||
Article 11, Volume 15, Issue 1, 1992, Page 100-105 PDF (228.74 K) | ||||
Document Type: Original Article | ||||
DOI: 10.21608/bfsa.1992.70220 | ||||
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Authors | ||||
Tarek A. Mohamed1; Adel F. Youssef1; Abd-El-Hamid N. Ahmed2 | ||||
1Department of Medicinal Pharmaceutical Chemistry, Faculty of Pharmacy, University of Assiut, Assiut 71516, A.R. Egypt | ||||
2Department of Organic Pharmaceutical Chemistry, Faculty of Pharmacy, University of Assiut, Assiut 71516, A.R. Egypt | ||||
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. | ||||
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