01393nas a2200157   4500008004100000245019300041210007000234260000800304490000900312520068600321100002301007700002301030700001601053700002501069856014101094       2021                        eng d00aConvenient and mild protocol for preparation of α –trimethylsilyloxyphosphonates using sulfamic acid and their oxidation to α – ketophosphonates in the presence of N-bromosuccinimide0 aConvenient and mild protocol for preparation of α trimethylsilyl  cSEP0 v20213 aA convenient and mild protocol was developed for the trimethylsilylation of α-hydroxyphosphonates using hexamethyldisilazane as the silylating agent in the presence of sulfamic acid (SA) as a heterogeneous solid acid catalyst in dichloromethane as the reaction medium. The utility of SA as the catalyst for deprotection of α-trimethylsilyloxyphosphonates to parent α-hydroxyphosphonates by making a switch to a protic solvent such as methanol was also demonstrated. Furthermore, the oxidation of α–trimethylsilyloxyphosphonates to corresponding α–ketophosphonates was achieved in excellent yields employing N-bromosuccinimide in the presence of catalytic quantity of AIBN.1 aMitragotri, Satish1 aKulkarni, Makarand1 aDesai, Uday1 aWadagaonkar, Prakash  uhttps://library.ncl.res.in/content/convenient-and-mild-protocol-preparation-%CE%B1-%E2%80%93trimethylsilyloxyphosphonates-using-sulfamic02135nas a2200253   4500008004100000022001400041245011400055210006900169260000800238300001100246490000700257520127700264653002601541653001301567653002301580653002101603100002301624700001801647700002101665700001601686700002401702700002501726856013001751       2021                        eng d  a0019-452200aRole of preparation parameters of Cu-Zn mixed oxide catalyst in solvent free glycerol carbonylation with urea0 aRole of preparation parameters of CuZn mixed oxide catalyst in s  cJUL  a1000900 v983 aSolvent-free carbonylation of glycerol with urea to glycerol carbonate (GC) was achieved over heterogeneous Cu-Zn mixed oxide catalyst. Cu-Zn catalysts with different ratios of Cu:Zn were prepared using co-precipitation (CP) and oxalate gel (OG) methods. As compared to CuO-ZnO(2:1) catalyst prepared by oxalate gel (OG) method, much higher conversion of glycerol and highest selectivity towards glycerol carbonate (GC) was achieved with CuO-ZnO_CP(2:1) catalyst. Physicochemical properties of prepared catalysts were investigated by using XRD, FT-IR, BET, TPD of CO2 and NH3 and TEM techniques. The effect of stoichiometric ratio of Cu/Zn, calcination temperature of CuO-ZnO catalysts and effect of reaction parameters such as molar ratio of substrates, time and temperature on glycerol conversion to GC were critically studied. Cu/Zn of 2:1 ratio, glycerol-urea 1:1 molar ratio, 145 degrees C reaction temperatures were found to be optimized reaction conditions to achieve highest glycerol conversion of 86% and complete selectivity towards GC. The continuous expel of NH 3 from reaction the mixture avoided formation of ammonia complex with CuO-ZnO catalyst. As a result of this, CuO-ZnO catalyst could be recycled up to three times without losing its initial activity.10aCo-precipitation (CP)10aGlycerol10aGlycerol carbonate10aOxalate gel (OG)1 aCharate, Shrinivas1 aShinde, Suhas1 aKondawar, Sharda1 aDesai, Uday1 aWadgaonkar, Prakash1 aRode, Chandrashekhar  uhttps://library.ncl.res.in/content/role-preparation-parameters-cu-zn-mixed-oxide-catalyst-solvent-free-glycerol-carbonylation