Tetra-n-butyl ammonium bromide (TBAB) was found to be an efficient phase-transfer catalyst for the synthesis of pyrido[2,3-d]pyrimidines by one-pot reaction of 6-aminouracils, aromatic aldehydes, and malononitrile or ethyl cyanoacetate in water under ultrasonic irradiation. The advantages of this method are the use of an inexpensive and readily available catalyst, short reaction time, easy work...

a general, mild and efficient protocol has been developed for the synthesis of esters and thioesters. the process has been taking place using tetra n-butylammonium iodide (tbai) as a phase-transfer catalyst and in the presence of potassium carbonate (k2co3). a wide range of esters and thioesters was prepared in high yields and suitable times by the treatment of alcohols, phenols and thiols with...

Due to the efficient product separation and catalyst immobilization, multi-phase catalytic systems are attractive for industrial applications. Nevertheless, it is usually difficult to decouple reaction and mass transfer kinetics such that the experimental determination of reaction kinetics is masked by mass transfer effects. A novel incremental identification methodology tailored to homogeneous...

Sulfonated polyether ether ketone (SPEEK) is categorized in a nonfluorinated aromatic hydrocarbon proton exchange membrane (PEM) group and considered as a suitable substitute for common per-fluorinated membranes, such as Nafion, due to wider operating temperature, less feed gas crossover, and lower cost. Since modeling results in a better understanding of a phenomenon, in this study a dynamic o...

The direct synthesis process of dimethyl ether (DME) from syngas in slurry reactors is considered to be promising because of its advantages in caloric transfer. In this paper, the influences of operating conditions (temperature, pressure and weight hourly space velocity) on the conversion of CO, selectivity of DME and methanol were studied in a stirred autoclave over Cu-Zn-Al-Zr slurry catalyst...

A water-soluble PdCl₂(NH₃)₂/cationic 2,2'-bipyridyl system was found to be a highly efficient catalyst for Stille coupling of aryl iodides and bromides with organostannanes. The coupling reaction was conducted at 110 °C in water, under aerobic conditions, in the presence of NaHCO₃ as a base to afford corresponding Stille coupling products in good to high yields. When aryltributylstannanes were ...