624-06-6Relevant academic research and scientific papers
Zinc-catalyzed depolymerization of polyethers to produce valuable building blocks
Enthaler, Stephan
, p. 850 - 859 (2014/06/23)
The recycling of polymers continues to be a significant matter for a sustainable society. In particular, the conversion of end-of-life polymers to monomers or suitable low-molecular weight chemicals creates a feedstock for new high-quality polymeric materials and contributes to conserve resources and allow overall an efficient waste-managing system. In the present study, we have set up a straightforward methodology for the depolymerization of artificial polyethers applying cheap and abundant zinc( II) salts as precatalysts. In the presence of bio-based fatty acid chlorides as depolymerization reagent well-defined chloroesters were accessible in good to excellent yields. Moreover, acetic anhydride and fatty acids were applied as depolymerization reagents resulting in the formation of diacetates in moderate yields. In both cases the obtained products (chloroesters, diacetates) can be useful building blocks in polymerization chemistry. Noteworthy, overall a recycling of polyethers are possible. Springer Science+Business Media New York 2014.
Kinetics and quantitative structure-activity relationships for pseudomonas sp. Lipase-catalyzed hydrolysis of both monoesters and diesters of ethylene glycol
Chiou, Shyh-Ying,Cheng, Yu-Ru,Lu, Chun-Ping,Lin, Yan-Fu,Lin, Long-Yau,Lin, Gialih
, p. 201 - 207 (2007/10/03)
The goal of this work is to study kinetics and quantitative structure-activity relationships for steady states of Pseudomonas sp. lipase-catalyzed hydrolysis of both diesters and monoesters of ethylene glycol. Based on the steady-state kinetics of the enzyme-catalyzed hydrolysis of the diesters of ethylene glycol, the diesters and the monoesters react simultaneously as soon as monoester has started to build up in the reaction medium. In other words, the apparent Km values of the diesters are the Km values of the diesters (KmA) plus the Km values of the monoesters (KmB), and all Vmax values are about the same. Moreover, the pH-stat titration curve of the enzyme-catalyzed hydrolysis of the diesters of ethylene glycol is initially hyperbolic, then there is a sharp falloff in the hydrolysis rate. The abrupt stoppage of the reaction (relaxation stage) may be due to the existence of two phases in the reaction medium, that is, the product (ethylene glycol) and the substrates (the diesters of ethylene glycol) are not miscible. Furthermore, quantitative structure-activity relationships for varied acyl groups of mono- and diesters of ethylene glycol are studied. The fact that both pKmA and pK mB values are linearly correlated with the hydrophobicity constant (π) but not with the electronic substituent constants (σ*) indicates that the affinity of these substrates for the enzyme depends only on the hydrophobicitv of substrates. Copyright
A novel one-pot synthesis of esters by exchange reactions between carbonates and anhydrides
Berti, Corrado,Colonna, Martino,Marianucci, Elisabetta,Sweileh, Bassam,Pilati, Francesco
, p. 917 - 927 (2007/10/03)
A new method for the synthesis of esters by exchange reaction between anhydrides and carbonates, without any solvent, in the presence of Ti or Sn based catalyst is presented.
The acyloin reaction using tethered diesters
Daynard, Tim S.,Eby, Paul S.,Hutchinson, John H.
, p. 1022 - 1028 (2007/10/02)
A study of the intramolecular acyloin condensation using diesters tethered by their alkoxide groups was undertaken.The goal was to provide a method for optimizing the yield of mixed acyloin products from the reaction of two different esters by utilizing tethered dissimilar esters as substrates.The results of the study show that the yield of the acyloin condensation is dependant on the tether length.Tethers of 8 and 14 carbons in length give yields comparable to those obtained from an intermolecular control reaction while shorter tethers give reduced yields of product.However, the use of mixed tethered diesters and a crossover experiment between two different tethered substrates provides a statistical distribution of products.These observations have been interpreted as resulting from a fragmentation of the initially formed radical anion intermediate that destroys the tethered nature of the substrate(s).
Preparation of Carboxylate Esters of Polyhydric Alcohols by Using a Sulfonated Charcoal Catalyst
Prager, Rolf H.,Yurui, Zhang
, p. 1003 - 1005 (2007/10/02)
Ethane-1,2-diol, propane-1,2-diol, butane-1,4-diol and propane-1,2,3-triol are readily esterified by carboxylic acids in near quantitative yields in the presence of a sulfonated charcoal catalyst.
THE METHYLATION OF CARBOXYLIC ACIDS USING METHYL TRICHLOROACETATE
Renga, James M.,Wang, Pen-Chung
, p. 77 - 82 (2007/10/02)
Metyl trichloroacetate has been shown to methylate carboxylic acids with the loss of chloroform and carbon dioxide.
