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Abstract: Carboxymethylated species were selectively synthesized from dimethyl carbonate (DMC) and bisphenol A (BPA) over TiO2/SBA-15. On the basis of catalyst characterization by means of XRD, FT-IR, HPLC and GC–MS, the relations between catalytic performance and catalyst properties were discussed. Si–O–Ti was active sites for reaction, and the interaction mode between Ti–O–Si and DMC was main factor to determine carboxymethylation and methylation. When DMC was attacked by Ti–O–Si on two oxygen atoms of CH3–O moiety, BPA attacked carbonyl carbon to form carboxymethylated products. If the interaction occurs through the oxygen of C BPA attacked methyl carbon to form methylated products. Chemisorbed H2O over TiO2/SBA-15 made DMC to act as methylating agent. After chemisorbed H2O was removed, carboxymethylated species of two-methylcarbonate-ended-BPA (DmC(1)) and one-methylcarbonate-ended-BPA (MmC(1)) were selectively synthesized. [Copyright &y& Elsevier]

Abstract: The mesoporous catalyst activities of supported molybdenum oxide for diphenyl carbonate (DPC) synthesis in liquid-phase transesterification of dimethyl carbonate (DMC) and phenol were investigated. The yields of DPC and methyl phenyl carbonate (MPC) were greatly improved when MoO3 was supported on SiMCM-41 to act as catalyst. MoO3/SiMCM-41 catalysts were characterized by X-ray diffraction (XRD), N2 adsorption–desorption isotherms, and Fourier transform infrared (FT-IR) spectroscopy. Characterized results revealed that the high activity sites of MoO3/SiMCM-41 were isolated MoO4 2− tetrahedral species and polymerized octahedral molybdenum oxide species. MPC formation increased with reaction time up to 4h and then decreased thereafter, and maximum MPC yield achieved 39.6%. The decrease of MPC yield after 4h might be ascribed to MPC disproportionation into DPC and reversible transesterification reaction. [Copyright &y& Elsevier]

Abstract: The systematic investigation was carried out to elucidate the direct reaction between CO2 and phenol over multiphase catalyst. Reactions carried out over ZrO2, TiO2, and KF/NaY+Mn2+ gave the high selectivity to 4-[4-hydroxybenzyl]phenol and 2-[2-hydroxybenzyl]phenol (HBP), and the maximum HBP selectivity of 68% was obtained with ZrO2 as catalyst. XRD patterns showed that metastable tetragonal ZrO2 was the active phase for HBP synthesis, and the bidentate carbonate on ZrO2 surface was responsible for high HBP selectivity. If Hbeta, HZSM-5, and Al2O3 were used as catalyst, the main product was diphenyl ether (DPE). But when reactions were catalyzed by KY and KF/NaY, xanthone became the main product; however, xanthone disappeared when KF/NaY coexisted with Mn(OCOCH3)2 as catalyst. The optimized reaction conditions for HBP synthesis over tetragonal ZrO2 are 350°C, 12h, and 4.0MPa CO2 pressure. [Copyright &y& Elsevier]

Abstract: Synthesis of diphenyl carbonate (DPC) from phenol and CO2 has been explored in CCl4 with zinc halides as catalyst. DPC yield and selectivity are influenced by the catalyst usage, reaction temperature, CO2 pressure and initial composition of reactants. The main byproduct is phenyl salicylate (PS). Zinc halides as Lewis acid exhibit high catalytic activity for DPC synthesis; ZnCl2 gives higher DPC yield and selectivity than ZnBr2 and ZnI2. High DPC yield was obtained with ZnCl2 as catalyst at 120°C and 4.0MPa. Based on the experimental observation, a possible reaction scheme has been proposed. The electronegativity of halogen ligand may determine the formation of DPC and PS; the Cl ligand in ZnCl2 with strong electronegativity may favor the formation of DPC. [Copyright &y& Elsevier]

Highlights: [•] Glycosidic bond hydrolysis couples with fructose dehydration to promote reaction. [•] 1,2-Glycosidic bond was more difficult cleavage than 1,4-glycosidic bond. [•] Amino group plays a great role in the rate-determining step of glucose isomerization. [•] COOH well catalyzes sucrose hydrolysis and fructose dehydration. [•] Tyrosine displays the best activity in sucrose conversion to 5-HMF. [ABSTRACT FROM AUTHOR]