The Determination of Stability Constants of Para Substituted N-Benzylideneaniline Metal Complexes by a Potentiometric Method

Abstract

In the present study, the stability constants of the complexes which were formed from N-benzylideneaniline (BDA), N-benzylidene-4-chloroaniline (BDCA), N-(4-chlorobenzylidene)aniline (CBDA), N-benzylidene-4nitroaniline (BDNA) and N-benzylidene-4-hydroxyaniline (BDHA) with chromium (III), manganese (II), cobalt (II), nickel (II), copper (II), zinc (II)and cadmium (II) were determined potentiometrically by using CalvinBjerrum and Irving-Rossotti methods. The protonation constants and dissociation constants of the ligands were found at 25°C and for 1=0,11 are given below:BDA logK, = pK, = 4,36 ; BDCA logK, = pK, = 3,60 ;CBDA logK, = pK, = 4,56 ; BDNA logK, = pK, = 2,45;BDHA logK, = pK 2 = 11,05 ; logK 2 = pK, = 5,75The formation constants of complexes formed using Cr(III), Mn(ll), Co(Il), Ni(ll), Cu(ll), Zn(II), Cd(II) are, respectively, 3.50; 3.90; 3.21; 3.90; 2.99; 3.30 and 3.30 for BDA; 3.35; 3.05; 3.05; 2.89; 2.93; 2.88 and 2.89 for 4.90; 5.26; 11.00; 6.52 and 4.40 for BDHA. None of these metals formed complexes with BDNA.The conditional formation constants and the pH ranges of formation of the resulting complexes were determined. The relative abundance was plotted using conditional formation constants of the complexes and the steps for the formation of the complexes were shown in graphs. The composition of metal complexes for monodentate ligands was determined as a metal/ligand ratio of 1:1. The composition of chromium and copper complexes for bidentate ligands was determined as a metal/ligand ratio of 1:2, while the ratio of other metal complexes was 1:1.

Formal α-Allylation of Primary Amines by a Dearomative, Palladium-Catalyzed Umpolung Allylation of N-(Aryloxy)imines

“…Mechanistically, the desired C–C bond formation could take place by direct regioselective addition of the deprotonated N -(aryloxy)­imine, a “soft” nucleophile (p K a ∼ 10), to the Pd-π-allyl species (outer-sphere mechanism) . However, the propensity of this highly delocalized anion to react with a high level of regioselectivity to deliver the desired product 6 was not easily explained.…”

“…6,153.2,142.9,139.8,136.8,132.2 (q,J = 32.3,31.2 Hz), 128.6, 125.7 (q, J = 3.5 Hz), 124.0 (q, J = 272.2 Hz), 118.0, 34.6, 30.3. 19 Preparation of 2,6-Di-tert-butyl-4-((3-methylbenzylidene)amino)phenol (3g). Following General Procedure A, m-tolylmethanamine (1.7 mL, 13.62 mmol, 1 equiv), 2,6-di-tert-butyl-1,4benzoquinone (3 g, 13.62 mmol, 1 equiv), and EtOH (18 mL) at 80 °C for 16 h afforded, after recrystallization from hexanes, 1.9 g (43%) of 3g as bright red crystals.…”

“…2 (dd,J = 246.3,9.1 Hz),135.2,128.4 (t, J = 10.8 Hz), 121.2, 117.7, 113.0−110.32 (dd, J = 20.9, 5.7 Hz), 47.3, 42.2. 19 F NMR (376 MHz, CDCl 3 ): δ −115.0. Spectral data are in accordance with published values.…”

“…The reaction was heated in an aluminum block to 80 °C with vigorous stirring. Aliquots (∼0.1 mL) were taken over time, diluted with EtOAc (∼1 mL) and hexanes (∼1 mL), washed with NH 4 Cl (sat) , concentrated, and analyzed by 1 H and 19 F NMR.…”