Showing papers on "Transesterification published in 1991"
323 citations
TL;DR: In this article, eight classes of transesterification catalysts are identified for the cogeneration of ethylene glycol plus dimethyl carbonate from ethylene carbonate and methanol.
143 citations
TL;DR: Using a similar technique, a long‐chain linear sucrose polyester has been prepared using Proleather, and may have applications as a water‐absorbent, biodegradable plastic for use as diapers and hygienic products, water‐treatment chemicals, and components of drug delivery systems.
Abstract: A variety of enzymes have been found to acylate sucrose in anhydrous pyridine. The enzymic reaction is highly selective; with trifluoroethylbutyrate as ester donor, enzyme-catalyzed transesterification of sucrose yielded sucrose 1'-butyrate and sucrose 6, 1'-dibutyrate. No sucrose-tributyrates were formed. Using a similar technique, a long-chain linear sucrose polyester has been prepared using Proleather, an alkaline protease from a Bacillus sp. This protease catalyzes the esterification of sucrose with bis(2, 2, 2-trifluoroethyladipate) in a 1:1 ratio to yield a sucrose-containing polyester with M(w) = 2100 and M(n) = 1600 for a polydispersity of 1. 31. Polymers with molecular weights in excess of 13, 000 have been prepared by this enzymic approach, indicating that molecules containing over 30 sucrose units have been produced. The polyester is extremely water soluble and soluble in polar organic solvents. As with the sucrose dibutyrate, the polyester has ester linkages at the C6 and C1' positions on the sucrose. The polyester can be depolymerized using Proleather in aqueous buffer, pH7. After 9 days in aqueous buffer, Proleather catalyzed the breakdown of the polyester to an M(w) of ca. 900. This sucrose-containing polyester may have applications as a water-absorbent, biodegradable plastic for use as diapers and hygienic products, water-treatment chemicals, and components of drug delivery systems.
138 citations
TL;DR: The enantioselectivity of the enzyme was markedly influenced by the nature of the organic solvent, but there was no correlation between enantiomeric ratio values (70–500) and either the hydrophobicity or the dielectric constant of the medium.
Abstract: Resolution of the mucolytic drug (±)- trans -sobrerol ( 1 ) was achieved by transesterification with vinyl acetate in organic media, catalyzed by free or immobilized Lipase PS. The enantioselectivity of the enzyme was markedly influenced by the nature of the organic solvent, but there was no correlation between enantiomeric ratio values (70–500) and either the hydrophobicity or the dielectric constant of the medium. With the enzyme immobilized onto Hyflo Super Cell and t -amyl alcohol as the solvent, the selectivity of Lipase PS for (−)- 1 was extremely high and, at 50 % conversion both (−)- trans -sobrerol and (+)- trans -sobrerol monoacetate were obtained in practically 100 % optical purity
93 citations
90 citations
TL;DR: The Porcine Pancreatic Lipase- and Mucor Esterase-catalyzed resolution of 1-phenylethanol 5 in four different alkyl carboxylate solvents, viz. methyl acetate, propionate and butyrate and ethyl acetate was evaluated.
86 citations
TL;DR: In this paper, two groups of solvents, cyclic and acyclic, show different feature on enantioselectivity in transesterification of a secondary alcohol under lipase-catalysis.
83 citations
Patent•
28 Jun 1991
TL;DR: In this paper, a process for the production of the fatty acid esters of lower monovalent alcohols by transesterification of fatty acid glycerides in the presence of basic catalysts is described.
Abstract: The invention relates to a process for the production of the fatty acid esters of lower monovalent alcohols by transesterification of fatty acid glycerides in the presence of basic catalysts The process according to the invention is characterized in that the transesterification is carried out in the presence of 0025 to 0045 mols of an alkali or alkaline earth metal compound, preferably sodium hydroxide, potassium hydroxide, sodium or potassium alcoholate, based on 100 g of fatty acid glyceride and the subsequent purification of the fatty acid esters is effected by the addition of 03 to 30 percent of water by hydration and separation of the catalyst residues and other impurities In contrast to the known processes, it is thus possible to obtain lower alcohols of any given high degree of transesterification and high purity from untreated oils and fats of natural origin with contents of up to 20 percent of fatty acids in the free state at ambient temperature and atmospheric pressure at minor alcohol excess by means of the simplest equipment
75 citations
TL;DR: The methyl ester of winter rape (MEWR) has been found to be a potentially useful substitute for diesel fuel as discussed by the authors, and the procedure used to produce MEWR for use as a diesel fuel substitute.
Abstract: The methyl ester of winter rape (MEWR) has been found to be a potentially useful substitute for diesel fuel. This article discusses the procedure used to produce MEWR for use as a diesel fuel substitute. Reaction variables, rates, equipment and detailed procedures for making 756 L (200 gal) batches of MEWR are discussed. Systems for methanol and glycerol recovery are included. Zero profit economic data are also presented.
74 citations
TL;DR: Repeated esterifications of Ac-Tyr-OH in acetonitrile by a CP-immobilized CT gave almost constant yields of the ester for more than 3 weeks.
61 citations
TL;DR: Depending on the structure of the substrate and the origin of the lipase chiral cyclopentane derivatives with high enantiomeric excess, good to excellent chemical yields could be obtained.
TL;DR: Polyunsaturated phospholipids can be prepared easily by transesterification of soyospholipid with fish oil by means of commercial lipases, and was rich in polyunsaturated fatty acids and linoleic acid.
Abstract: Transesterifications were investigated to determine a means for preparing polyunsaturated phospholipids simply from soy phospholipid, sardine oil, and two kinds of microbial lipases originating fromCandida cylindracea andRhizopus delemar.
TL;DR: In this paper, the boron trifluoride-methanol transesterification method was used to depolymerize soil humin preparations from three contrasted soil types in order to examine the presence of biopolyester moieties in these non-colloidal soil humic fractions.
Abstract: The boron trifluoride-methanol transesterification method was used to depolymerize soil humin preparations from three contrasted soil types in order to examine the presence of biopolyester moieties in these non-colloidal soil humic fractions. The humin samples were isolated physically from the soil (ultrasonic treatment and flotation) and purified by extractions with organic and inorganic solvents. Such humin fractions amounted to between 10–20% of the soil organic C and their CHCl3-soluble transesterification products (6–8.5% wt) were analyzed by combined gas chromatography-mass spectrometry. When subjected to transesterification, the humins yielded approximately equal amounts of aromatic and alkyl compounds. The former fraction consisted mainly of phenolic acids. The major constituents of the alkyi fraction were ω-hydroxy fatty acids, di- and trihydroxy monobasic acids and long-chain dibasic acids, in addition to epoxy monobasic acids, mono and dienoic fatty acids, and a minor proportion of n- and b-fatty acids and β-hydroxy monobasic acids. The results obtained suggest that an important amount of lipid polymers, such arc cutins and suberins, tends to accumulate in the soil humin fraction incorporating a series of compounds derived from microbial metabolism.
TL;DR: In this paper, the Porcine Pancreatic Lipase (PPL)-catalyzed transesterification of 1-phenyl-1,2-ethanediol 1, 2phenyl -1, 2-propanediol 2 and 1,3-butanediol 7 in methyl propionate as solvent was evaluated.
TL;DR: In this paper, the kinetics of transesterification of copolyester based on isophtalic acid, 4-hydroxybenzoic acid and hydroquinone were studied.
Abstract: The kinetics of transesterification of the liquid crystal copolyester based on isophtalic acid, 4-hydroxybenzoic acid and hydroquinone were studied. From the temperature dependence of the rate constant, an activation energy of ca. 157 kJ/mol was evaluated, which is essentially identical to that obtained for poly(ethylene terephtalate).
TL;DR: Using catalysis by 1,3-dichlorotetrabutyldistannoxane, 1,n-diol diacetates were selectively converted into the corresponding monoacetates.
Abstract: Using catalysis by 1,3-dichlorotetrabutyldistannoxane, 1,n-diol diacetates were selectively converted into the corresponding monoacetates.
TL;DR: In this article, the kinetic resolution of rac-3-(2-methylphenoxy)propane-1,2-diol ( rac-1, Mephenesin) by sequential lipase-catalyzed transesterification with vinyl acetate in tetrahydrofuran/triethylamine in the presence of lipase Amano PS is described.
Abstract: The kinetic resolution of rac-3-(2-methylphenoxy)propane-1,2-diol ( rac-1 , Mephenesin) by sequential lipase-catalyzed transesterification with vinyl acetate in tetrahydrofuran/triethylamine in the presence of lipase Amano PS is described.
TL;DR: The pyrolytic derivatization technique provides a rapid way for generating a chemotaxonomically characteristic profile of fatty acid methyl esters from a single bacterial colony.
TL;DR: In this paper, the formation of low molecular weight side products during the esterification reaction between ethylene glycol and dimethyl terephthalate was investigated, and it was shown that the presence of incorporated diethylene glyco glycol within the polymer led to the creation of low-molecular-weight side products.
Abstract: The formation of certain low molecular weight by-products during the esterification reaction between ethylene glycol and dimethyl terephthalate was investigated. The result obtained showed that the presence of incorporated diethylene glycol within the polymer led to the formation of low molecular weight side products. An alcoholysis reaction involving the ethylene glycol and the ester was found to show a mechanism that is analogous to that of an ester interchange resulting in the production of the acid and the diethylene glycol precursor of the dioxane by-product.
TL;DR: A series of pyranosidics and furanosidic monosaccharide derivatives were monoacetylated in the 6-position with high regioselectivity and good to excellent yields by the pancreatin-catalyzed transesterification with vinyl acetate in the solvent system tetra- hydrofuran/triethylamine.
Abstract: A series of pyranosidic and furanosidic monosaccharide derivatives were monoacetylated in the 6-position with high regioselectivity and good to excellent yields by the pancreatin-catalyzed transesterification with vinyl acetate in the solvent system tetra- hydrofuran/triethylamine.
TL;DR: In this paper, the standard homogeneous metathesis catalyst consisting of WCl 6 and Me 4 Sn in chlorobenzene as solvent was used for the transesterification of palm oil.
TL;DR: Lipase from Candida cylindracea catalyses two reactions between racemic hydroxyacid esters and octanoic acid in heptane: esterification of the hydroxy group, leading to acyloxy acid esters, and transesterification via acidolysis, liberating the free hydroxy acids.
TL;DR: In this article, the influence of different reaction conditions on Pseudomonas cepacia lipase (PCL) catalyzed esterification of several chiral allylic alcohols (2-(1-hydroxyethyl)acrylonitrile and some closely related compounds) have been investigated.
Abstract: The influences of different reaction conditions on Pseudomonas cepacia lipase (PCL) catalyzed esterification of several chiral allylic alcohols (2-(1-hydroxyethyl)acrylonitrile and some closely related compounds) have been investigated. These compounds are possible precursors in the synthesis of the antibiotic Nyccomycin. An increase in the reaction temperature led to an increased final conversion, decreased enantioselectivity of the reaction, and a reduction of the residual activity of the lipase. PCL is thermostable and catalytically active for more than 100 hours at 100 °C. Variation of the chain length of the acyl group of the esters used as cosubstrates had only a small influence on the conversion. As expected, the alcohol generated during the synthesis had a strong negative influence on the progress of the reaction. PCL showed strong substrate selectivity for some of the tested allylic alcohols. The enantioselectivity changed from substrate to substrate.
TL;DR: The effect of varying amounts of linoleic acid hydroperoxidases on the activity of an immobilized lipase, Lipozyme, used for the transesterification of fats has been studied and loss of activity is due to generation of free radicals in the enzyme following hydroperoxide decomposition.
Abstract: The effect of varying amounts of linoleic acid hydroperoxidases on the activity of an immobilized lipase, Lipozyme, used for the transesterification of fats has been studied. The initial activity of the enzyme is not significantly reduced even by a peroxide value of 50 mequiv/kg, but the operational stability is reduced if the peroxide value of the oil is above 5 mequiv/kg, with the rate of enzyme inactivation increasing the peroxide value. A sample with initial peroxide value of 50 mequiv/kg caused a 50% loss of activity after eight batch treatments of 10 h per treatment. The loss of activity is due to generation of free radicals in the enzyme following hydroperoxide decomposition.
TL;DR: In this paper, the Porcine Pancreatic Lipase (PPL)-catalyzed transesterification in methyl acetate as the solvent leads to corresponding acetates and remaining methanols both of high enantiomeric purity.
TL;DR: A solvent system of vinyl acetate-tetrahydrofuran at refluxing temperature was quite effective to perform enzymatic transesterification of highly crystalline substrate, such as 2-hydroxytetracosanoic acid as discussed by the authors.
Patent•
04 Jul 1991
TL;DR: In this article, a bis(2-alkoxyphenyl) carbonate of the formula (wherein R is alkyl) is transesterified to give a polycarbonate.
Abstract: PURPOSE:To efficiently obtain a high-quality polycarbonate through a short-time reaction under mild conditions without using any harmful compound by transesterifying a specified carbonic ester compound and a bisphenol. CONSTITUTION:A bis(2-alkoxyphenyl) carbonate of the formula (wherein R is alkyl) [e.g. bis(2-methoxyphenyl) carbonate] and a bisphenol (e.g. bisphenol A) are transesterified to give a polycarbonate. By this method, a polycarbonate with sufficiently high molecular weight can be efficiently obtained under mild conditions (low temperature) through a short-time reaction. In addition, the 2-alkoxylphenol eliminated from the ester by transesterification can be satisfactorily removed from the polymer at a relatively low temperature, e.g. during the reaction; therefore, a high-quality polycarbonate can be efficiently manufactured without using harmful phosgene, etc.
Patent•
02 Sep 1991
TL;DR: In this article, a transesterification with monohydric lower alcohols using metal alcoholates as transterification catalyst is described. But the reaction in this case is carried out in a tubular flow reactor, after which glycerol is removed in a continuous flow centrifuge, and the product is further purified in a filter system.
Abstract: In a process and an apparatus for the continuous production of fatty acid esters from vegetable and animal oils or fats by transesterification with monohydric lower alcohols using metal alcoholates as transesterification catalyst, a mixture of alkali metal oxides and/or alkaline earth metal oxides and alkali metal alcoholates and/or alkaline earth metal alcoholates is employed as transesterification catalyst. The reaction in this case is carried out in a tubular flow reactor (7), after which glycerol is removed in a continuous flow centrifuge (10), and the product is further purified in a filter system (15).
Patent•
30 Aug 1991TL;DR: In this article, a solvent-free two-stage transesterification process for polyol and fatty acid esters of an easily removable alcohol is described. But the reduced levels of difatty ketones and.beta.-ketoesters are achieved by controlling the level of generated alcohol in the liquid phase of the reaction mixture and heating the reaction reaction mixture to certain temperatures during the second stage of this improved process.
Abstract: An improved. solvent-free, two-stage transesterification process for preparing, from a polyol and fatty acid esters of an easily removable alcohol. highly esterified polyol fatty acid polyesters having reduced levels of difatty ketones and .beta.-ketoesters is disclosed. These reduced levels of difatty ketones/.beta.-ketoesters are achieved by controlling the level of generated alcohol in the liquid phase of the reaction mixture and heating the reaction mixture to certain temperatures during the second stage of this improved process. Other optional reaction conditions, such as keeping the molar ratio of fatty acid esters to polyol within a specified range and reducing the level of basic catalyst, can also be used during the second stage reaction to further reduce the level of difatty ketones and/or .beta.-ketoesters.