Disclosed herein is an unprecedented cobalt-catalyzed trifluoromethylation–peroxidation of unactivated alkenes. In this process the hydroperoxide acts as a radical initiator as well as a coupling partner. The cheap and readily available sodium trifluoromethanesulfinate serves as the CF3 source in the reaction. Various alkenes are transformed into vicinal trifluoromethyl-peroxide compounds in moderate to good yields.

A novel N,N,N-tridentate ligand known as 2-(2-pyridylmethylamino)ethylbenzimidazole (pymaeb) was designed and synthesized. This ligand in combination with disodium pyridine-2,6-dicarboxylate (pydic) reacted with RuCl3 to afford a novel complex Ru[2-(2-pyridymethylimino)ethylbenzimidazole]pyridinedicarboxylate [Ru(pymieb)(pydic)] which was characterized by NMR, IR, HR-MS and single crystal X-ray diffraction. Crystal structure analysis revealed that the complex has a distorted octahedral geometry. The complex showed excellent activity for the oxidation of various alcohols with TBHP as oxidation under mild and solvent-free conditions.A novel Ru(II) complex Ru(pymieb)(pydic) was synthesized and characterized by NMR, FT-IR, HR-MS and single crystal X-ray diffraction. The complex showed excellent activity for the oxidation of various alcohols with TBHP as oxidant under mild and solvent-free conditions.

•Folic acid was enriched and recovered using foam fractionation from wastewater.•Folic acid was recovered from the one-stage foamate by crystallization.•CTAB was used as the collector and reused by two-stage foam fractionation.•Foam fractionation coupled with crystallization recovered folic acid efficiently.A technology of foam fractionation coupled with crystallization was developed for effectively recovering materials from wastewaters with low concentrations. The wastewater containing folic acid (FA) was used as a system and cetyltrimethyl ammonium bromide (CTAB) was chosen as a collector to recover FA from its wastewater. The results showed that the technology could effectively enrich and purify FA with a low concentration of 6 mg/L from its wastewater. In foam fractionation, the enrichment ratio and recovery percentage of FA were 86.1% and 69.1%, respectively. CTAB could be reused using a two-stage foam fractionation. In crystallization, the recovered FA had 98.0% in purity and it met the quality standard (GB 15570-95). The total recovery percentage of FA was 66.0% by the technology of foam fractionation coupled with crystallization. The technology could be effective not only for recovering FA from its wastewater but also for recovering other trace materials from their wastewaters.

•50 mg/L was determined as the lowest concentration of SDS in foam separation.•In the one-stage foam column, E was improved but R decreased significantly.•Surface excess was measured under continuous operation at low concentrations.•A two-stage foam separation technology using only one column was developed.•Using this technology, E and R increased to 28.0 and 94.2%, respectively.ObjectiveThe lowest concentration of sodium dodecyl sulfate (SDS) separated capably from its feed solution using a one-stage foam separation was determined. Both enrichment ratio and recovery percentage of SDS were increased and SDS concentration of the residual solution was decreased at its lowest concentration.Materials methodThe effects of SDS concentration and superficial gas velocity on foaming height and enrichment ratio of SDS were studied in order to determine the lowest SDS concentration in foam separation. A two-stage foam separation technology using only one column was developed to improve the performances at the lowest SDS concentration.ResultsThe results showed that the lowest SDS concentration in foam separation was 50 mg/L. In the one-stage foam separation, SDS surface excess increased with increasing the height of the liquid phase and the pore diameter of gas distributor, thus enrichment ratio increased from 1.9 to 7.2 and however, recovery percentage decreased and SDS concentration of the residual solution significantly increased. In the developed two-stage foam separation, enrichment ratio and recovery percentage increased to 28.0 and 94.2%, respectively and at the same time, SDS concentration of the residual solution decreased to 6.0 mg/L under the operating conditions of SDS concentration of the feed solution of 50.0 mg/L, loading volume of 0.630 L and superficial gas velocity of 1.33 mm/s.

A novel deep eutectic solvent supported TEMPO (DES–TEMPO) composed of N,N-dimethyl-(4-(2,2,6,6-tetramethyl-1-oxyl-4-piperidoxyl)butyl)dodecyl ammonium salt ([Quaternium-TEMPO]+Br−) and urea was prepared. An efficient catalytic system for the oxidation of alcohols with molecular oxygen as terminal oxidant has been developed from DES–TEMPO and Fe(NO3)3·9H2O. The DES–TEMPO/Fe(NO3)3 system showed good performances on the selective oxidation of various alcohols to the corresponding aldehydes and ketones under mild and solvent-free conditions. The DES could be recovered easily and recycled up to five times in the oxidation of benzyl alcohol without significant loss of catalytic activity.