Cobalt immobilized on hydroxyapatite as a low-cost and highly effective heterogeneous catalyst for alkenes epoxidation under mild conditions

Abstract

Transition metal Co immobilized on hydroxyapatite even with low loading of 0.05 wt% is a low-cost and highly effective heterogeneous catalyst for alkenes epoxidation at 30 °C with O2 and iso-butyraldehyde as co-oxidant.

A new and efficient methodology for olefin epoxidation catalyzed by supported cobalt nanoparticles

“…Based on our experimental observations and those previously made by other authors [ 15 – 17 41 – 44 ], we assumed that a radical oxidation process could be taking place. To test this assumption, the epoxidation of styrene was carried out under the optimized conditions by adding hydroquinone (5 mg, 0.045 mmol) as radical scavenger.…”

“…20% selectivity in the epoxidation of 1-decene as the only substrate tested [ 42 ]. On the other hand, among the peroxide-free oxidation processes, a Co 3 O 4 /SBA-16 catalyst for the epoxidation of limonene in AcOEt [ 43 ] and a Co/HAP catalyst in DCM as the solvent [ 44 ] have been very recently reported. Both of these catalytic systems gave good conversions to the desired epoxides and allowed the use of molecular oxygen as oxidant but require the use of high amounts (400–500% excess) of isobutyraldehyde as co-reductant.…”

“…On the other hand, the use of supported cobalt nanoparticles as efficient catalysts for the epoxidation of olefins has received increasing attention in the last years. In most cases, a crucial influence of the support (TiO 2 , HAP, CNTs, SBA, SiO 2 ), the oxidant agent (molecular oxygen or TBHP) and the solvent (DMF, MeCN, ethyl acetate, DMSO, solvent free) on the activity and selectivity of the nanocatalysts has been noted [27,[41][42][43][44].…”

W/HAP catalysed N-oxidation of tertiary amines with H2O2 as an oxidant

“…0.616 g) and stirred at 293 K for 24 h. The catalysts were filtered off, washed, and dried at 353 K overnight. 6 , 31 , 32 The tungsten content in the W/HAP catalyst was found to be 0.0340 Wt.%.…”

Study on the epoxidation of chain olefins using biquaternary ammonium phosphotungstic acid phase transfer catalysts under no‐solvent condition

“…[14] Furthermore, these heterogeneous systems typically operate under harsh conditions, such as high temperature to achieve high yields. [15,16] Among numerous transition metal-based catalysts, the polyoxometalate catalysts have attracted wide attention due to their excellent catalytic activity [17,18] and easy adjustment of acid or redox properties. Furthermore, they could effectively minimize the undesired side reactions and demonstrate high tunable catalytic activity targeted at specific oxidation reactions.…”