Design and introduction of quaternary ammonium hydroxide-functionalized graphene oxide quantum dots as a pseudo-homogeneous catalyst for epoxidation of α,β-unsaturated ketones

In present work, design and synthesis of a novel pseudo-homogeneous catalyst is described. For this purpose, amine-functionalized graphene oxide quantum dots (N-GOQDs) were prepared from graphene oxide (GO) by a facile one-step oxidative fragmentation approach. The prepared N-GOQDs were then modified with quaternary ammonium hydroxide groups. Various characterization techniques clearly revealed that the quaternary ammonium hydroxide-functionalized GOQDs (N-GOQDs/OH^-) have been successfully synthesized. TEM image revealed that the GOQDs particles are almost regularly spherical in shape and mono-dispersed with particle sizes < 10 nm. The efficiency of the synthesized N-GOQDs/OH^- as a pseudo-homogeneous catalyst in epoxidation of α,β-unsaturated ketones in the presence of aqueous H₂O₂ as an oxidant at room temperature was investigated. The corresponding epoxide products were obtained in good to high yields. This procedure has the advantages of a green oxidant, high yields, involvement of non-toxic reagents and reusability of the catalyst without discernible loss in activity.

Organometallic 3d transition metal NHC complexes in oxidation catalysis

The development of processes for the selective oxidation of hydrocarbons is a major focus in catalysis research. Making this process simultaneously environmentally friendly is still challenging. 3d transition metals are...

Efficient epoxidation of chalcones with urea-hydrogen peroxide under ultrasound irradiation

An efficient epoxidation of chalcones with urea-hydrogen peroxide (UHP) under ultrasound irradiation was carried out in 78-93% yields. Compared with the classical method, the advantages of protocol are to use a safer oxidant, mild conditions, no toxic solvent and shorter reaction time.

Diastereo- and enantioselective synthesis of alpha,beta-epoxyketones using aqueous NaOCl in conjunction with dihydrocinchonidine derived phase-transfer catalysis at room temperature. Scope and limitations

In this paper we present studies into the scope and limitations of asymmetric PTC epoxidation of enones and the oxidation-epoxidation of allylic alcohols using aqueous NaOCl in conjunction with a dihydrocinchonidine derived quaternary ammonium salt catalyst.

Enantioselective Alkylation of β-Keto Esters by Phase-Transfer Catalysis Using Chiral Quaternary Ammonium Salts

Catalytic enantioselective alkylation promoted by a quaternary ammonium salt from cinchonine as a phase transfer catalyst is described. Treatment of cyclo beta-keto esters with alkyl halide under mild reaction conditions afforded the corresponding alpha-alkylated beta-keto esters in moderate to excellent yields with high enantiomeric excesses