scholarly journals General and Practical Potassium Methoxide/Disilane-Mediated Dehalogenative Deuteration of (Hetero)Arylhalides

2018 ◽  
Vol 140 (35) ◽  
pp. 10970-10974 ◽  
Author(s):  
Xin Wang ◽  
Ming-Hui Zhu ◽  
David P. Schuman ◽  
Dayou Zhong ◽  
Wen-Yan Wang ◽  
...  
Keyword(s):  
2010 ◽  
Vol 8 (2) ◽  
pp. 219-225
Author(s):  
Yoeswono Yoeswono ◽  
Triyono Triyono ◽  
Iqmal Tahir

A study on palm oil transesterification to evaluate the effect of some parameters in the reaction on the reaction kinetics has been carried out. Transesterification was started by preparing potassium methoxide from potassium hydroxide and methanol and then mixed it with the palm oil. An aliquot was taken at certain time interval during transesterification and poured into test tube filled with distilled water to stop the reaction immediately. The oil phase that separated from the glycerol phase by centrifugation was analyzed by 1H-NMR spectrometer to determine the percentage of methyl ester conversion. Temperature and catalyst concentration were varied in order to determine the reaction rate constants, activation energies, pre-exponential factors, and effective collisions. The results showed that palm oil transesterification in methanol with 0.5 and 1 % w/w KOH/palm oil catalyst concentration appeared to follow pseudo-first order reaction. The rate constants increase with temperature. After 13 min of reaction, More methyl esters were formed using KOH 1 % than using 0.5 % w/w KOH/palm oil catalyst concentration. The activation energy (Ea) and pre-exponential factor (A) for reaction using 1 % w/w KOH was lower than those using 0.5 % w/w KOH.   Keywords: palm oil, transesterification, catalyst, first order kinetics, activation energy, pre-exponential factor


1979 ◽  
Vol 35 (3) ◽  
pp. 733-736 ◽  
Author(s):  
R. Destro ◽  
T. Pilati ◽  
M. Simonetta
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2017 ◽  
Vol 19 (3) ◽  
pp. 643-646
Author(s):  
Timo Wendling ◽  
Eugen Risto ◽  
Benjamin Erb ◽  
Lukas J. Gooßen

Terminal alkynes were converted to (E)-β-alkoxyacrylates via regio- and stereoselective addition of dialky carbonates catalyzed by potassium methoxide.


1972 ◽  
Vol 50 (5) ◽  
pp. 678-689 ◽  
Author(s):  
D. H. Hunter ◽  
S. K. Sim

The mechanism of the cyclization and 1,3-proton shift of 1,3,5-triaryl-2,4-diaza-1,3-pentadienes (1) catalyzed by phenyllithium and by potassium methoxide–methanol has been studied. On the basis of substituent effects, hydrogen–deuterium exchange, isotope effects, and solvent effects, it was deduced that both the cyclization and prototropy involve a common W-shaped carbanion which rapidly cyclizes. A kinetic deuterium isotope effect of 2 was calculated for protonation of this intermediate carbanion in methanol.


1986 ◽  
Vol 169 (2-3) ◽  
pp. L348-L354 ◽  
Author(s):  
Robert A. DePaola ◽  
Jan Hrbek ◽  
Friedrich M. Hoffmann
Keyword(s):  

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