Synthesis, characterization and solid‐phase extraction properties of novel bis(diazo‐azomethine) ligands supported on mesoporous silica

Abstract

The novel mesoporous silica-supported bis(diazo-azomethine) compounds have been synthesized and characterized successively. In the first step, 1,3-phenylenedimethanamine and 4,4′-diaminodiphenylmethane were diazotized, and the obtained bis(diazonium) cations were coupled with 2,4-dihydroxybenzaldehyde. The synthesized bis(diazo-carbonyl) compounds, 5,5′-((1,3-phenylenebis(methylene))bis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde) (A1) and 5,5′-((methylenebis(4,1-phenylene)) bis(diazene-2,1-diyl))bis(2,4-dihydroxybenzaldehyde) (A2) were chemically supported on amino-modified silica-gel (as L1 and L2). Elemental analysis, liquid chromatography-mass spectroscopy, liquid-phase NMR ( 1 H and 13 C) and solid-phase NMR (CP-MAS 29 Si and 13 C), FT-IR, TG/DTA, scanning electron microscopy and energy-dispersive X-ray spectroscopy techniques were used for characterizations of all the synthesized compounds. The syringe and batch techniques were applied for the solid-phase extraction properties of Pb(II), Cu(II), Cd(II) and Cr(III) ions using an inductively coupled plasma-atomic emission spectroscopy instrument. The recoveries of Pb(II), Cu(II), Cd(II) and Cr(III) ions have been achieved to 95-99% with the (RSDs) of ± 2-3% in optimum conditions.

Synthesis and characterization of graphene oxide‐based hybrid ligand and its metal complexes: Highly efficient sensor and catalytic properties

“…In the probable reaction mechanism, 2MN substrate is oxidized to 2‐methyl‐1‐naphthol in the first step that is slow and thus this is the rate‐determining step. Secondly, 2‐methyl‐1‐naphthol oxidizes to 2‐methyl‐1,4‐naphthalenediol (Figure ) . If the first step can be controlled using a suitable catalyst and oxidant, selectivities can be increased.…”

“…If the first step can be controlled using a suitable catalyst and oxidant, selectivities can be increased. Sulfuric acid and acetic acid form peroxyacetic acid in the catalysis medium and this mixture controls the oxygen transportation to aromatic rings that is led by a catalyst in the oxidation reaction and using peroxyacetic acid oxidant increases the catalytic activity according to the possible mechanism …”

“…A modified catalysis process was used in the oxidation of 2MN to 2MNQ (vitamin K 3 ) according to previous studies . The ratio of catalyst to oxidant to substrate was selected as 1:100:1000 in the catalytic reactions.…”

“…Vitamin K 3 is also used for new‐borns deficient in vitamin K. Vitamin K 3 is used in vitamin premixes in the feed of chickens and fish as a nutritional supplement. The lack of vitamin K 3 causes weakening of bones and increasing the calcification of arteries and other soft tissues . Vitamin K 3 is industrially produced via the oxidation of 2‐methylnaphthalene (2MN) in chromic acid with 50–60% selectivity.…”

“…After the synthesis of 1 kg of vitamin K 3 , 18 kg of chromium‐containing waste arises that is quite difficult to treat. In addition, the reaction selectivity and efficiency are very low in the industrial oxidation process because of the oxidation reaction being quite difficult to control …”