Selectivity engineering in hydroxyalkoxylation of phenol by ethylene carbonate using calcined hydrotalcite

The high consumption of mono-ethylene glycol phenyl ether in various sectors requires clean and green synthesis. Herein, we report an efficient, selective and green route of hydroxylation using calcined hydrotalcite (CHT) for the preparation of mono-ethylene glycol phenyl ether. Various types of solid base catalysts were prepared and well characterized by TGA–DSC, FTIR, XRD, CO2-TPD, NH3-TPD, SEM and BET surface area. The catalyst CHT (3:1) possesses very high activity for hydroxyalkoxylation of phenol and ethylene glycol with 96% conversion at 180 °C in 2 h with catalyst loading of 0.03 g cm−3. The insight of reaction reveals that it is kinetically controlled with second-order reaction and follows power law model. The apparent activation energy for the reaction is 21.3 kcal mol−1. The catalyst is highly reusable and shows green chemistry prospective and gives excellent results up to four runs

Potassium modified La-Mg mixed oxide as active and selective catalyst for mono-methylation of phenylacetonitrile with dimethyl carbonate

Mono-methylated products of phenyl acetonitrile (PAN) are in demand for the preparation of non-steroidal anti-inflammatory drugs (NSAID) such as Ketoprofen, Ibuprofen and Naproxen. 2-Phenylpropionitrile is prepared from PAN and finds uses in pharmaceutical industry. Herein, we report a novel catalyst potassium promoted lanthanum-magnesium oxide as well as a novel reaction using it. It is used for the first time for the selective mono-methylation of phenylacetonitrile to 2-phenylpropionitrile with dimethyl carbonate as a methylating agent. A variety of catalysts were synthesized, characterized such as MgO, La2O3, La2O3-MgO and potassium (1–4 wt%) on La2O3-MgO and used in mono-methylation of phenylacetonitrile with dimethyl carbonate (DMC). Two wt% K/La2O3-MgO catalyst was the best and showed 100% conversion of phenylacetonitrile and 100% selectivity of 2-phenyl propionitrile at mole ratio of PAN: DMC of 1:30 at 150 °C in 2 h. The characterization of fresh and used 2 wt% K/La2O3-MgO was done using different techniques such as FTIR, SEM, TGA-DSC, CO2-TPD, XRD, and BET surface area analysis. Two wt% K/La2O3-MgO catalyst was used to study the reaction mechanism and a kinetic model developed using LHHW type of mechanism with all species being weakly adsorbed. The apparent activation for mono-methylation of phenylacetonitrile to 2-phenylpropionitrile was found to be 13.77 kcal/mol

Green Synthesis of Veratraldehyde Using Potassium Promoted Lanthanum–Magnesium Mixed Oxide Catalyst

Veratraldehyde is an important chemical used in perfumery, agrochemical, and pharmaceutical industries. Current processes of manufacture of veratraldehyde use homogeneous catalysts, which make them highly polluting, creating problems of disposal of effluents and product purity. In the current work, veratraldehyde was synthesized from O-alkylation of vanillin with an environmentally benign reagent, dimethyl carbonate. A series of potassium loaded La₂O₃–MgO were prepared by the incipient wetness impregnation method, and their performance was evaluated vis-à-vis MgO, La₂O₃, La₂O₃–MgO, and a series of 1–4 wt % K/La₂O₃–MgO. All catalysts were characterized by different techniques, such as N₂ adsorption/desorption, XRD, TGA-DSC, FT-IR, CO₂-TPD, and SEM techniques. The effect of different loadings (1–4 wt %) of potassium on La₂O₃–MgO was studied, among which 2 wt % K/La₂O₃–MgO showed the best activity and selectivity due to high dispersion of potassium and high basicity in comparison with the rest. The activity of 2 wt % K/La₂O₃–MgO in O-methylation of vanillin with dimethyl carbonate (DMC) was closely associated with basicity. Various parameters were studied to achieve the maximum yield of the desired product. The maximum conversion was found with catalyst loading of 0.03 g/cm³ and mole ratio of vanillin and DMC of 1:15 at 160 °C in 2 h. The reaction follows pseudo-first-order kinetics for the O-methylation of vanillin. The energy of activation was found to be 13.5 kcal/mol. Scale-up was done using the kinetic model to observe that the process could be scaled up using the process parameters. The overall process is clean and green