Variability of the Transformations of 4-Hydroxy-6-methyl-2H-pyran-2-one under Modified Biginelli Reaction Conditions
A modified version of the three-component Biginelli reaction of 4-hydroxy-6-methyl-2H-pyran-2-one with aromatic aldehydes in urea under conventional heating and microwave activation has been studied. Depending on the order of addition of the reactants, su
Strashilina,Mazhukina,Fedotova
p. 102 - 106
(2018/06/14)
Hydrophobic effect of silica functionalized with silylated Ti-salicylaldimine complex on limonene oxidation by aqueous hydrogen peroxide
This research work describes the effect of hydrophobicity in inducing the diffusion of alkene substrates to the catalytic active sites. The aim of this research is to improve the catalytic activity by tailoring the degree of hydrophobicity of the catalyst. Silica functionalized with solid non-silylated Ti-salicylaldimine complex was prepared at room temperature by mixing imine ligand and Ti(IV) sulphate solution. The amorphous, solid complex formed was further silylated with octadecyltrimethoxysilane (OTMS) to induce hydrophobicity. The composition of the resulting silica functionalized with silylated Ti-salicylaldimine complex was varied with Ti:OTMS molar ratio in the range of 1:1/4 to 1:4 at room temperature. The successful attachment of alkylsilyl groups to silica functionalized with Ti-salicylaldimine complex was proven by the FTIR and 29Si solid state NMR spectra. The FTIR spectra showed increasing peak area for sp 3 C-H stretching mode (ca. 2919 cm-1 and 2850 cm-1) and decreasing peak area for Si-OH band with increasing amount of OTMS. TGA showed less water content with higher amount of alkylsilyl groups in the catalyst. This is in agreement with the lower kinetic rate of water adsorption capacity for the hydrophobic catalysts prepared. It was observed that the hydrophobic, silica functionalized with silylated Ti-salicylaldimine complex exhibited higher substrate conversion and reusability compared to the non-silylated catalyst.
Yuan, Lai Sin,Chandren, Sheela,Efendi, Jon,Ho, Chin Siong,Nur, Hadi
p. 1905 - 1917
(2015/12/30)
Time-resolved E.S.R. Study of Triplet Ketoamines Generated by Intramolecular Proton Transfer in Free Schiff Bases
Non-phosphorescent triplet states of the ketoamine forms of several free Schiff bases generated by intramolecular proton transfer have been observed using a time-resolved e.s.r. method.
Mixed Tri- and Bi-dentate Schiff-base Complexes of Technetium(V) and Rhenium(V). The Crystal Structure of N-(2-Oxidophenyl)salicylideneiminato-NOO')oxo(8-quinolinolato-NO)technetium(V)
Six-co-ordinate complexes of technetium(V) and rhenium(V) containing the MO3+ core with tri- and bi-dentate Schiff-base ligands were synthesized and characterized.The complexes with general formula 1)L) 1/sup