ABSTRACT
2-Silyl-cyclobutene(di)ones are obtained by an addition/substitution approach on dimethyl squarate using silyl anions. The acetal and in particular the thioacetal derivatives readily undergo electrocyclic ring opening to reactive silyl(vinyl)ketenes.
Subject(s)
Alkanes/chemistry , Alkanes/chemical synthesis , Dynamins/metabolism , Genes, ras/genetics , Mitogen-Activated Protein Kinases/metabolism , Pyrrolidinones/chemistry , Pyrrolidinones/chemical synthesis , Signal Transduction , Biological Products/chemistry , Genes, ras/physiology , Humans , Mitogen-Activated Protein Kinases/chemistry , Molecular Structure , Proteomics/standards , Structure-Activity RelationshipABSTRACT
Owing to the large amount of glycerol that is formed as a by-product during biodiesel production, there have been great efforts to develop new reactions and processes based on glycerol as a renewable feedstock. One example is the telomerization of butadiene with glycerol which provides an atom-economic route to amphiphilic molecules. The reaction is catalyzed by homogeneous palladium catalysts which necessitates efficient catalyst recycling. By employing an aqueous biphasic system, an increased selectivity towards the desired mono-ethers was observed in the telomerization reaction. The performance of the reaction and separation and recycling of the catalyst were optimized by the addition of organic solvents as well as cyclodextrins. By adding cyclodextrins, the conversion of glycerol could be increased and the leaching of palladium could be reduced. Leaching of palladium into the organic phase could be lowered also by using 2-octanol or 2-propanol as additional solvents. Furthermore, the catalyst system could be stabilized by adding nitriles or phosphonium salts, and radical polymerization, which leads to fouling, could be inhibited successfully.
