UV SPECTROPHOTOMETRIC DETERMINATION OF pK's OF 1,2,4-TRIAZOLINE-3-THIONES IN SODIUM HYDROXIDE SOLUTIONS

Abstract

Using UV spectroscopy the dissociation constants of previously synthesized 4,5-disupstituted-1,2,4-triazoline-3-thiones are determinate. The UV spectra were recorded in aqueous sodium hydroxide solutions at different pH values in the range from 190 to 360 nm, immediately after preparation of the suspension. The pK TH values were obtained experimentally, graphically and by the Characteristic Vector Analysis method. Results show that the investigated compounds have two dissociation processes. The first process belongs to the dissociation of SH proton, while the second dissociation process is dissociation of OH proton.

Solvent and Copper Ion-Induced Synthesis of Pyridyl–Pyrazole-3-One Derivatives: Crystal Structure, Cytotoxicity

“…The result of X-ray single-crystal analysis is consistent with that of NMR. It must be noted that the C6–O distances for 1 and 2 are 1.359 Å and 1.338 Å, respectively, which is close to the similar pyrazole–OH bond (1.329 Å) [ 34 , 35 ]. The result indicates that the bond C6–O is a C–O single bond.…”

“…The molecular structure of 1 is shown in Figure 1 . All bond distances in the pyrazole ring show partial double-bond character, which suggests a delocalized π-electronic system throughout the ring [ 33 , 34 ]. The bond angles and bond lengths ( Table S1 ) in the pyrazole ring are within the normal ranges, close to the tabulated value [ 33 ].…”

“…Single-crystal X-ray diffraction analysis revealed that 3 belongs to the monoclinic space group P 2 1 / c with a = 11.5817(12) Å, b = 12.3223(10) Å, c = 15.8773(11) Å, α = 83.661(6) Å, β = 71.060(8) Å, γ = 65.385(9) Å and V = 1947.7(3) Å 3 ( Figure 3 ). In 3 , all bond distances in the pyrazole rings ( II and III ) show partial double-bond character, which suggests a delocalized π-electronic system throughout the ring [ 34 ]. The bond angles and bond lengths ( Table S3 ) in the pyrazole ring are within the normal ranges, close to the tabulated value [ 33 ].…”