ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

4-substituted 2-nitrophenylguanidines .2. Acid-base properties and structure

P. Pazdera, M. Potáček, and J. Šimeček

Department of Organic Chemistry, Faculty of Natural Sciences, J. E. Purkyně University, CS-611 37 Brno

Abstract: Dissociation constants K_I of the dissociation of 4-X-2-nitrophenyl- guanidinium cation in water (X = H, CH₃ , OCH₃ , Br, CI, OPh, CN, N0₂) were measured by potentiometry. A linear dependence of pK_I{ on the Hammett constants σ_p of the substituents X with the value  ϱ=-0.522 was found. Dissociation constants K'_II which characterize the dissociation of 4-X-2- -nitrophenylguanidine were measured by the UV VIS spectrophotometric method. A linear dependence was found of pK'_II  on Hammett constants  σ_p^- of the substituent X with the value  ϱ=1.143 and a linear correlation between  pK'_II and the value of the chemical shift δ of the hydrogen atom H-4.

Full paper in Portable Document Format: 424a539.pdf

Chemical Papers 42 (4) 539–546 (1988)