Oxygenation Of Organic Compounds Research Articles

Peroxidative bromination and oxygenation of organic compounds: Synthesis, X-ray crystal structure and catalytic implications of mononuclear and binuclear oxovanadium(V) complexes containing Schiffbase ligands

Treatment of of ( R, R)-N,N-salicylidene cyclohexane 1,2-diamine(H 2L 1) in methanol with aqueous NH 4VO 3 solution in perchloric acid medium affords the mononuclear oxovanadium(V) complex [VOL 1(MeOH)]·ClO 4 ( 1) as deep blue solid while the treatment of same solution of ( R, R)-N,N-salicylidene cyclohexane 1,2-diamine(H 2L 1) with aqueous solution of VOSO 4 leads to the formation of di-(μ-oxo) bridged vanadium(V) complex [VO 2L 2] 2 ( 2) as green solid where HL 2 = ( R, R)-N-salicylidene cyclohexane 1,2-diamine. The ligand HL 2 is generated in situ by the hydrolysis of one of the imine bonds of HL 1 ligand during the course of formation of complex [VO 2L 2] 2 ( 2). Both the compounds have been characterized by single crystal X-ray diffraction as well as spectroscopic methods. Compounds 1 and 2 are to act as catalyst for the catalytic bromide oxidation and C–H bond oxidation in presence of hydrogen peroxide. The representative substrates 2,4-dimethoxy benzoic acid and para-hydroxy benzoic acids are brominated in presence of H 2O 2 and KBr in acid medium using the above compounds as catalyst. The complexes are also used as catalyst for C–H bond activation of the representative hydrocarbons toluene, ethylbenzene and cyclohexane where hydrogen peroxide acts as terminal oxidant. The yield percentage and turnover number are also quite good for the above catalytic reaction. The oxidized products of hydrocarbons have been characterized by GC Analysis while the brominated products have been characterized by 1H NMR spectroscopic studies.

Metalloporphyrins in the biomimetic oxidative valorization of natural and other organic substrates

Cheap and abundant natural products can be transformed into products of higher commercial value. One of the approaches for the functionalization of organic compounds is their oxidation in the presence of an oxygen atom donor, under the influence of a suitable catalyst. Metalloporphyrins, with structures based on the well known meso-tetraphenylporphyrin (TPPH2), are amongst the catalysts commonly studied and have demonstrated to be efficient in the oxygenation of organic compounds. These transformations have been studied in the presence of different oxygen atom donors. However, our biomimetic oxidative approach is based on the use of clean and environmentally benign hydrogen peroxide in the presence of metalloporphyrins. This approach will be outlined in this review.

An Unconventional Cobalt‐Catalyzed Aerobic Oxidation of Tertiary Nitrogen Compounds to N‐Oxides.

The propensity of cobalt complexes to bind with molecular oxygen[1] and the use of such dioxygen–cobalt complexes as catalysts for various oxidation reactions have been subjects of intensive research in recent years.[2] The oxygenation of organic compounds catalyzed by such dioxygen–cobalt complexes and with aldehyde as a sacrificial agent[3] has led to several important methodologies for the epoxidation of olefins,[4] oxidation of sulfides to sulfones,[5] and oxidation of imines to oxaziridines.[6] However, the oxygenation of organic compounds, in which molecular oxygen serves as the oxidant and cobalt complexes as catalysts under ambient conditions without the sacrificial agent, although a desirable goal, has not been very successful. To the best of our knowledge there are only two relevant literature reports describing the oxygenation of trialkylphosphanes[7] and olefins, and cyclic ethers.[8] The cobalt Schiff base complexes 1,[4b] 2,[9] 3,[10] and 4[11] are well known to bind with molecular oxygen[4b,9,10] and show very high reactivity in oxygenation reactions with molecular oxygen as the oxidant along with an aldehyde as a sacrificial agent, but there are no reports on the oxygenation of organic compounds with these complexes as catalysts and molecular oxygen as the sole oxidant. Oxidation of tertiary nitrogen compounds to N-oxides is an important synthetic transformation. In the search for environmentally friendly methods for this transformation the use of hydrogen peroxide with the catalysts methyltrioxorhenium(vii),[12] manganese porphyrin,[13] flavin,[14] TS-1,[15] molecular sieves,[16] and tungstate-exchanged Mg/Al-layered double hydroxide[17] has been reported. In continuation of our studies on oxidation with molecular oxygen as the primary oxidant[18] we report here on the first successful oxidation of tertiary nitrogen compounds 5 to N-oxides 6 catalyzed by cobalt(ii) Schiff base complexes (Scheme 1). A wide variety of tertiary nitrogen compounds were oxidized to give their corresponding N-oxides in nearly quantitative yields by simply bubbling molecular oxygen into a solution of the tertiary nitrogen compound in 1,2dichloroethane at room temperature in the presence of 5-5 molecular sieves and with the cobalt Schiff base complex 1 as the catalyst. These results are summarized in Table 1. Pyridines containing electron-donating groups (Table 1, entries 2, 3, and 6) were found to react faster than pyridines bearing electron-withdrawing groups (Table 1, entries 4 and

An unconventional cobalt-catalyzed aerobic oxidation of tertiary nitrogen compounds to N-oxides.

The propensity of cobalt complexes to bind with molecular oxygen[1] and the use of such dioxygen–cobalt complexes as catalysts for various oxidation reactions have been subjects of intensive research in recent years.[2] The oxygenation of organic compounds catalyzed by such dioxygen–cobalt complexes and with aldehyde as a sacrificial agent[3] has led to several important methodologies for the epoxidation of olefins,[4] oxidation of sulfides to sulfones,[5] and oxidation of imines to oxaziridines.[6] However, the oxygenation of organic compounds, in which molecular oxygen serves as the oxidant and cobalt complexes as catalysts under ambient conditions without the sacrificial agent, although a desirable goal, has not been very successful. To the best of our knowledge there are only two relevant literature reports describing the oxygenation of trialkylphosphanes[7] and olefins, and cyclic ethers.[8] The cobalt Schiff base complexes 1,[4b] 2,[9] 3,[10] and 4[11] are well known to bind with molecular oxygen[4b,9,10] and show very high reactivity in oxygenation reactions with molecular oxygen as the oxidant along with an aldehyde as a sacrificial agent, but there are no reports on the oxygenation of organic compounds with these complexes as catalysts and molecular oxygen as the sole oxidant. Oxidation of tertiary nitrogen compounds to N-oxides is an important synthetic transformation. In the search for environmentally friendly methods for this transformation the use of hydrogen peroxide with the catalysts methyltrioxorhenium(vii),[12] manganese porphyrin,[13] flavin,[14] TS-1,[15] molecular sieves,[16] and tungstate-exchanged Mg/Al-layered double hydroxide[17] has been reported. In continuation of our studies on oxidation with molecular oxygen as the primary oxidant[18] we report here on the first successful oxidation of tertiary nitrogen compounds 5 to N-oxides 6 catalyzed by cobalt(ii) Schiff base complexes (Scheme 1). A wide variety of tertiary nitrogen compounds were oxidized to give their corresponding N-oxides in nearly quantitative yields by simply bubbling molecular oxygen into a solution of the tertiary nitrogen compound in 1,2dichloroethane at room temperature in the presence of 5-5 molecular sieves and with the cobalt Schiff base complex 1 as the catalyst. These results are summarized in Table 1. Pyridines containing electron-donating groups (Table 1, entries 2, 3, and 6) were found to react faster than pyridines bearing electron-withdrawing groups (Table 1, entries 4 and

Oxygenation of organic compounds a novel oxidative cleavage 1,2-glycols

Oxygenation of organic compounds a novel oxidative cleavage 1,2-glycols