二氧化硅负载磷钨酸催化甘油与丙酮的缩合反应

利用溶胶-凝胶法制备了二氧化硅负载的磷钨酸(TPA/SiO2)固体酸催化剂,用XRD和N2-吸附脱附对TPA/SiO2固体酸催化剂进行了表征,研究了催化剂在甘油与丙酮缩合反应中的催化性能,考察了催化剂的焙烧温度、磷钨酸质量分数、反应时间和催化剂质量等对反应性能的影响.结果表明:TPA/SiO2固体酸是平均颗粒为20.9...     

Ketalization of glycerol to solketal in supercritical acetone

In the last few years, the increasing production of biodiesel has led to an overproduction of glycerol, the main byproduct of this industry. This paper reports on the ketalization of glycerol in supercritical acetone to give solketal (4-hydroxymethyl-2,2-dimethyl-1,3-dioxolane), an oxygenated compound useful as chemical and fuel additive for gasoline, diesel and biodiesel. The application of supercritical fluids (SCFs) in the chemical synthesis was explored to carry out reactions to obtain the above cyclic ketal. The experimental results reveal a drastic change in the reaction behavior when the critical condition of acetone is reached (T = 508 K). Below 508 K the reaction rate of solketal production is very low, but above this temperature a rapid increase in the reaction rate is observed. Finally, the reaction rate is stabilized at 533 K and higher temperatures due to the conversion of glycerol to acrolein and polymeric products as side reactions.     

1,2-Isopropylidene Glycerol Carbonate: Preparation,Characterization, and Hydrolysis

Utilization of excess glycerol supplies derived from the burgeoning biodiesel industry is of major importance to the oleochemical industry as the economic viability of the biodiesel and oleochemical industries are closely linked to glycerol prices. Carbonates based on glycerol, such as glycerol carbonate, are gaining prominence due their simple preparation, interesting properties and chemistry. Herein, the synthesis, physical properties, and chemistry of an interesting glycerol-based carbonate (4, bis[(2,2-dimethyl-1,3-dioxolan-4-yl)methyl] carbonate; 1,2-isopropylidene glycerol carbonate or solketal carbonate) is reported. Carbonate interchange reaction between solketal (isopropylidene glycerol) and diethyl carbonate in the presence of sodium methoxide catalyst gave solketal carbonate, 4, in 65–70% isolated yields. Carbonate 4 was characterized using Fourier transform infrared spectroscopy (FTIR), ¹H and ¹³C nuclear magnetic resonance spectroscopy (NMR), and gas chromatography–mass spectrometry (GC/MS). The kinematic viscosity at 40 °C, refractive index, and melting point of 4 were determined to be 26.7 mm²/s, 1.4460, and below −50 °C, respectively. Using a high frequency reciprocating rig (HFRR) testing apparatus neat 4 was shown to have lubricity properties similar to fatty acid esters. Hydrolysis of the isopropylidene groups converted carbonate 4 into polyol 6, bis(2,3-dihydroxypropyl) carbonate in good yields (84%). Carbonate polyol 6 was characterized by ¹H and ¹³C NMR and represents a potentially novel polyol component that may be useful in the syntheses of interesting carbonate containing esters and polymers. Disclaimer: Product names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable.     

The Enzymatic Synthesis and Characterization of Disolketal Iminodiacetic Acid (DSIDA)

Disolketal iminodiacetic acid (DSIDA) has been synthesized from the enzyme‐catalyzed condensation reaction between derivatives of iminodiacetic acid (IDA) and glycerol. According to all available literature, DSIDA is a novel diester that has never been synthesized. It is a precursor to water‐soluble polyhydric alcohols and helps to address the global need of the biodiesel industry to find new uses for glycerol. Reacting diMe‐IDA with solketal, a protected glycerol, produced DSIDA in yields as high as 96.4% under optimal reaction conditions of 70 °C and 200 Torr for 24 h. The reaction was monitored using ATR‐IR and a validated GC method. ATR‐IR monitored the disappearance of the primary solketal alcohol and the appearance of cyclic solketal ether bonds in the molecular backbone of the intermediates and product. Structural analysis of the intermediates and products was performed using two‐dimensional NMR, GC, GC–MS and elemental analysis. All spectral data was in agreement with the proposed structures for the chemical reaction. Thermal profiles were determined by TGA to be single‐stage decompositions above 160 °C.     

Solventless ketalization of glycerol to solketal with acetone over the ionic liquid[P(C4H9)3C14H29][TsO]

The ketalization of glycerol with acetone was conducted over an ionic liquid [P(C_4H_9)_3C_(14)H_(29)][Ts O](TTPT) in a batch reactor. A scheme to obtain the purified product using TTPT as a homogeneous catalyst is proposed and a maximum solketal yield of 86% is achieved at acetone/glycerol molar ratio of 6/1, reaction time of 0.5 h, reaction temperature of 303 K, catalyst amount of 5 wt% of glycerol. TTPT was recycled and reused for ten times without obvious losses in terms of quantity and activity. Furthermore, effects of various experimental parameters(stirring speed, catalyst loadings, temperature and reactant composition) on the reaction kinetics are investigated. In terms of kinetics modeling, Kγis fitted by reactant composition at the temperature range 298 K–323 K, which was a concise strategy that showed good precision in the kinetics fitting. The activation energy for this ketalization reaction was evaluated to be 28.2 k J·mol~(-1). In addition, the kinetics of the reaction at a temperature exceeding the boiling point of acetone were also studied. We believe that all the results are important for further development of a technology for the continuous synthesis of solketal.