The acidity constants of 4-(2-pyridylazo)resorcinol (PAR, Scheme 1) in binary mixtures of methanol–water at 25 ◦C and an ionic strength of 0.1 M have been determined spectrophotometrically. DATa ANalysis (DATAN) program applied for determination of acidity constants. As percent of methanol increases in solvent mixtures the pKa constants also increased. There is linear relationship between acidi...

In the title mol-ecule, C(18)H(12)N(2)OS, the dihedral angle between the two fused-ring systems is 7.2 (1)°. The hydr-oxy group forms an intra-molecular hydrogen bond with the imino group.

The title Schiff base compound, C(18)H(14)N(2)O(3), has an inter-mediate state between NH and OH tautomers. The mol-ecular structure is stabilized by an O-H⋯N hydrogen bond. The dihedral angle between the naphthalene ring system and the benzene ring is 37.44 (5)°.

In the present paper, a solid phase extraction system for separation and preconcentration of nickel (ng g(-1)) in saline matrices is proposed. It is based on the adsorption of nickel(II) ions onto an Amberlite XAD-2 resin loaded with 1-(2-pyridylazo)-2-naphthol (PAN) reagent. Parameters such as the pH effect on the nickel extraction, the effect of flow rate and sample volume on the extraction, ...

The title compound, C(22)H(18)N(2)O, was synthesized from naphthalen-2-ol, benzaldehyde and pyridin-2-amine. In the crystal, mol-ecules are linked into centrosymmetric R(2) (2)(16) dimers by pairs of O-H⋯N hydrogen bonds. The mol-ecular conformation is stabilized by an N-H⋯O hydrogen bond. The dihedral angle between the naphthylene ring system and the phenyl ring is 72.86 (12)°.

The binary adsolubilization behaviors of 2-naphthol +biphenyl and 2-naphthol +1, 3-dichlorobenzene in a cationic fluorocarbon surfactant adsorbed layer formed on TiO2 have been investigated as a function of pH. In the binary adsolubilization of 2-naphthol+biphenyl, the adsolubilized amount of 2-naphthol increases gradually until pH 7 and then sharply with a further increase of pH, whereas the a...