The fractional rate of cholesterol esterification in very low density lipoprotein- and low density lipoprotein-depleted plasma (FERHDL) was studied in normolipidemic subjects and in individuals with hyperlipidemia and proven coronary artery disease (CAD). The FERHDL was significantly higher than the FER in whole plasma and was significantly higher in normal men than in normal women. In addition, men and women with primary hyperlipidemia had significantly higher FERHDL values relative to their sex-matched controls. The most significant increases in FERHDL values, however, were observed in individuals with CAD. In all patient groups, FERHDL was positively correlated with plasma triglyceride concentration. In addition, FERHDL was negatively related to plasma high density lipoprotein (HDL) cholesterol concentration in all groups except in men with CAD and in normolipidemic women. The gradient gel electrophoretic pattern of HDL from individuals with either low or high FERHDL values indicated an ...

4‐Dodecylbenzenesulfonic acid (DBSA) was employed in the esterification of oleic acid (OA) and the trans‐esterification of oleic oil (OO) with 1‐butanol as alcohol in the presence of various degrees of excess water. Under these conditions DBSA was found to be a highly active esterification catalyst regardless of excess water content, but was found to be a less effective for trans‐esterification reactions. Lipophilic alcohols of differing straight and branched C3‐6 chains were also tested on mixtures of OA/water (1:1) in DBSA‐catalyzed esterifications; OO/water (1:1) in trans‐esterifications; and OA/OO/water (1:1:1) in simultaneous esterifications and trans‐esterifications. While longer straight chain alcohols generally gave a two‐fold increase in yield of their corresponding alkyl oleates to 80%+, we observed a doubling from 30-50% to 60-95% of alkyl oleate yield for the OO/OA/water mixture. DBSA‐catalyzed amidations of OO and methyl oleate emulsions in water were conducted ...

Ethynyl-estradiol was shown to decrease the rate of biosynthesis of saturated, mono-, di-, tri- and tetraenic fatty acids in liver tissue and to increase the esterification of the newly synthesized fatty acids into triglycerides and phospholipids. The most distinct activation of esterification was found, if newly synthesized saturated fatty acids changed to triglycerides and tetraenic acids--into phospholipids. Ethynyl-estradiol stimulated also in liver tissue the esterification of exogenous saturated and unsaturated fatty acids into triglycerides and phospholipids, while relative esterification of unsaturated fatty acids into phospholipids tended to increase. The data obtained suggest that stimulation of endo- and exogenous fatty acids esterification into triglycerides and phospholipids of liver tissue may be important in pathogenesis of estrogen-induced hypertriglyceridemia ...

Fluorinated carbogens are an important class of organic compounds due to their wide range of applications. Fluorinated derivatives find use in the preparations of pharmaceutical and agrochemical products. A comparative study of enzyme-catalyzed transesterification reactions of a series of fluorinated and non-fluorinated esters has been undertaken in this work using three different lipases CAL-B, PSC-II and AK. The effect on the enzyme-catalyzed transesterification reaction of esters was evaluated based on the number of aryl fluorine atoms present in the substrate, and on the relative size of the fluoromethyl group and its proximity to the reaction site. The effect of lipase catalysts on the rate of reaction and on enantioselectivity was also assessed in order to compare the behavior of fluorinated and non-fluorinated primary and secondary esters. In the enzymecatalyzed transesterification of 1-phenylethyl acetate and its fluorinated derivatives; CAL- (B) shows tolerance to the presence of ...

TY - JOUR. T1 - Preparation of surfactant-coated lipase for the esterification of geraniol and acetic acid in organic solvents. AU - Huang, S. Y.. AU - Chang, H. L.. AU - Goto, M.. PY - 1998/5/15. Y1 - 1998/5/15. N2 - Lipolytic esterification of geraniol and acetic acid in an organic solvent was investigated. A surfactant-coated lipase (SCL) was designed to enhance the esterification. The ester product, geranyl acetate, is an important component of flavor and fragrance compounds. Fatty acids such as acetic acid cause substantial deactivation of lipase, resulting in low esterification yields. SCL is expected to prevent direct contact of organic solvent and the substrates with lipase, thereby decreasing enzyme deactivation. The lipase from Candida cylindrecea interacted with the surfactant Span 85 in a buffer of pH 5.2 to form SCL for the esterification of geraniol and acetic acid. The SCL possessed low solubility in organic solvents which is beneficial for the recovery and repeated usage of ...

Sulfated zirconia catalysts obtained by employing chlorosulfuric acid show significantly higher activity in the esterification of fatty acids with different alcohols compared with catalysts made using sulfuric acid. The superior performance results from higher sulfur content, larger pores and stronger acid sites. These catalysts are robust and do not leach out sulfonic groups. Catalyst performance depends strongly on the sulfation reagent and the calcination conditions of the intermediate zirconium hydroxide. A series of kinetic experiments was carried out with lauric acid and various alcohols (methanol, 2-ethylhexanol, propanols and butanols). The new catalysts are ca. five times faster when using primary alcohols independent of the alcohol chain length. When using secondary and tertiary alcohols the reaction rate drops considerably. This is explained by a linear free energy relationship of substituent reactivity. The kinetic investigation shows that chlorosulfated zirconia is suitable as a ...

Physical and chemical properties:. FASCAT®4101 is an amorphous, hydrolytically stable butyl tin chloride dihydroxide. It can be used for esterification, polycondensation and transesterification reactions. The catalyst is used to synthesize saturated polyester resin for powder coatings.. FASCAT® 4101 is used to produce unsaturated polyester resins for gel coating, sheet molding and casting molding applications. The temperature range of ester and antioxidant formation in the transesterification reaction is 140-180°C.. The production of PBT engineering resins for the automotive and construction markets requires the same temperature. It provides shorter esterification time, transesterification cycle time, lower reaction temperature and effective use of equipment.. CAS 13355-96-9. EC 236-406-1. Molecular formula C4H11CIO2SN. Specifications: different specifications, can be packaged according to customer needs. Product English name: Butylchlorodihydroxytin. CAS Number: 13355-96-9. EINECS Number: ...

Esterification of Polysaccharides by Thomas Heinze starting at $62.00. Esterification of Polysaccharides has 2 available editions to buy at Alibris

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The process of converting an acid into an alkyl or aryl derivative. Most frequently the process consists of the reaction of an acid with an alcohol in the presence of a trace of mineral acid as catalyst or the reaction of an acyl chloride with an alcohol. Esterification can also be accomplished by enzymatic processes ...

TY - GEN. T1 - Transesterification of lipids in a continuous bioreactor. AU - Forssell, Pirkko. AU - Poutanen, Kaisa. AU - Linko, Pekka. N1 - Project code: ELI0804. PY - 1993. Y1 - 1993. M3 - Conference article in proceedings. BT - Instrumental methods for determination of oil, protein and other constituents of oilseeds and meals. CY - Anaheim. T2 - 84th AOCS Annual Meeting. Y2 - 25 April 1993 through 29 April 1993. ER - ...

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The synthesis of citronellyl butyrate by direct esterification reaction catalyzed by immobilized lipase from Candida rugosa was studied in a continuous packed bed reactor using n-hexane as organic solvent. Parameters such as residence time, temperature, and pH were examined. The optimum conversion was obtained at a flow rate of 1 ml/min (residence time 8 min), temperature of 50 °C, and pH 7.5. At high temperature, biocatalyst was rapidly deactivated with respect to time. The immobilized lipase was stable at pH range of 6 to 9. The deactivation of biocatalyst was increased at pH of immobilized lipase 4 and 10 in comparison with pH range from 5 to 9. The esterification reaction in packed-bed reactor was modeled by ping pong model and ping pong with product inhibition model. The observed kinetics behaviour of esterification reaction was found to follow a ping pong with product inhibition model. In this study, the conversion of butyric acid and stability of immobilized lipase was higher in the system with

Laurate esters of catechin and condensed tannins were synthesized by both transesterification and conventional acylation techniques. Transesterification was developed as an alternative route to prepare flavonoid fatty acid esters as a prerequisite to advancing potential applications. Resorcinol, catechin, and two condensed tannins were transesterified with vinyl esters, and the resulting products were compared to those formed with lauroyl chloride. The esterified products, including catechin pentalaurate, were characterized both chemically and thermally. Transesterification produced partially substituted derivatives, with a preference for substitution at the catechol ring. Melt features were identified at or below 50°C, which were dependent upon the level of substitution. In addition, the tannin laurates showed thermal stability to at least 100°C and moderate retention of antioxidant properties ...

A mathematical model describing chemical kinetics of transesterification of palm-based methyl esters with trimethylolpropane has been developed. The model was developed by utilizing nonlinear regression method, which is an efficient and powerful way to determine rate constants for both forward and reverse reactions. A comparison with previous study which excludes the reverse reactions was made. The model was based on the reverse mechanism of transesterification reactions and describes concentration changes of trimethylolpropane, monoesters and diesters production. The developed model was validated against data from the literature. The reaction rate constants were determined using MATLAB version 7.2 and the ratios of rate constants obtained were well in agreement with those reported in the literature. A good correlation between model simulations and experimental data was observed. It was proven that both methods were able to predict the rate constants with plausible accuracy.

Linear aromatic polyesters of bisphenols and dicarboxylic compounds are prepared by transesterification polymerization in either a fully continuous process or in a semi-continuous process wherein a first stage is conducted batchwise and a second stage is conducted in a continuous manner wherein the second stage employs a wiped film reactor. The processes are preferably conducted in the presence of a catalyst in liquid form, and further under conditions wherein the catalyst is introduced to the polymerization concurrent with the introduction of liquid phase reactants to avoid substantial heating of the reactants in contact with the catalyst prior to onset of the transesterification reaction. The products of the processes have an unexpectedly low polydispersity.

Lipogenesis and esterification aspects of the adipose tissue adaptation to energy intake in pregnant and lactating swine by Katrine Louise Swanson Parmley Download PDF EPUB ...

Taken together, these observations may be interpreted to suggest a change in the structure [and/or] function of the plasma membrane of adipocytes and/or interstitial space in RO subjects. Theoretically, an alteration which allowed more rapid mixing of outgoing and incoming FFA, would produce a decrease in the re-esterification of lipolyzed FFA. This model suggests that the surface of the adipocyte functions as a mixing pool for FFA fluxing in and out of the cell, resulting in a reciprocal relationship between lipolysis rate and FFA uptake (see above). This concept is consistent with recent work regarding mechanisms of uptake and release of FFA from adipocytes, in that uptake and release appear to occur at physically separate sites (25, 26). Whether significant mixing of incoming and outgoing FFA occurs intracellularly has been a point of contention, with some investigators reporting little (27) or no (28) evidence for this in rats, and others suggesting that substantial mixing does occur in ...

CheckOrphan is a non-profit organization located in Basel, Switzerland and Santa Cruz, California that is dedicated to rare, orphan and neglected diseases. CheckOrphan offers users an interactive and dynamic platform for all these diseases. This strategy allows visitors to be updated daily on all the latest news and interact with people internationally. This is essential, because due to the nature of these diseases, there is not a large concentration of individuals within any given proximity ...

The main focus of this thesis lies on enzymatic asymmetric organic reactions. In the first part ofthis work, we looked into the lipase-catalyzed transesterification and hydrolysis at the molecularlevel. It was shown that the low enantioselectivity of CALB-catalyzed transesterification of a δ-functionalized alkan-2-ol to its acetate does not correlate at all with the high enantioselectivity ofthe CALB-catalyzed hydrolysis of the corresponding acetate in water. This lack of correlation isunusual and for unfunctionalized alkan-2-ol derivatives there is a very good correlation betweenthe enantioselectivity of transesterification of the alcohol and hydrolysis of the correspondingacetate with a high enantioseletivity in both cases. The results confirm previous predictions frommolecular modeling. The water effect was mimicked by CALB variant Ala281Ser, whichshowed an enhanced enantioselectivity in transesterification of δ-functionalized alkan-2-olscompared to wild type CALB.. In the second part of ...

A deep eutectic solvent (DES) consisting of choline chloride and glycerol (1:2 molar ratio) was prepared and used as the solvent in CaO-catalyzed transesterification of rapeseed oil to produce biodiesel. In addition to its solvent role, DES activated commercial CaO to be a catalyst for the transesterification reaction. The yield of fatty acid methyl ester (FAME) with the addition of DES. Get Price ...

PROCESS INFORMATION Transesterification (also called alcoholysis) is the reaction, normally catalized, of a fat or oil with an alcohol to form fatty acid esters (known as FAME when the alcohol is methanol) and glycerol [1]. Fig 1 shows the main steps: • From the raw feedstock, the pure plant oil (PPO) should be extracted.

An aromatic polycarbonate and an active-hydrogen compound are subjected to the transesterification reaction in the presence of a transesterification catalyst under a reduced pressure condition followed by reaction with a salicylic acid ester derivative expressed by the following chemical formula (1), ##STR1##{wherein X is methyl or ethyl, and Y is a carbonyl group or a divalent functional group expressed by the following formula (2), ##STR2##(where Z is an alkylene group having a carbon number of 1 to 30, an arylene group having a carbon number of 6 to 30 or an aralkylene group having a carbon number of 7 to 30)}.An aromatic polycarbonate having a high molecular weight can be produced by this process.

Methods: Commercially available carboxyl functionalized single walled carbon nanotubes (SWCNT-COOH) were refluxed in concentrated HNO3/H2SO4 mixture and then neutralized to pH 7, centrifuged and dialyzed to remove salts, and ultimately freeze dried. We also purchased SWCNT, purified and oxidized it using the mineral acids to obtain SWCNT-COOH. The SWCNT-COOH was conjugated covalently to mPEG2000 via esterification reaction between carboxyl group of SWCNT-COOH and hydroxyl group of mPEG2000 using 4-dimethylaminopyridine as catalyst. Water was added in the final reaction. After work up, the resulting precipitate, SWCNT-mPEG, was filtered and rinsed with water, and dried by lyophilization. The SWCNT-COOH and the SWCNT-mPEG were characterized by several techniques including Raman, FTIR and NMR spectroscopies ...

forms, in an ATP-dependent manner, a thioester linkage between its active site cysteine and the carboxy terminus of ubiquitin. The activated ubiquitin moiety is then transferred from E1 to the active site cysteine in E2 through a trans-thiol esterification reaction. The UBC enzyme later ligates ubiquitin directly to substrate proteins with or without the assistance of N-end recognizing proteins (E3). In most species there are many forms of UBC (at least 9 in yeast) which are implicated in diverse cellular functions. The UBC core is an alpha/beta domain containing one four-stranded antiparallel beta-sheet and four alpha-helices (see ...

Escriba M, Eras J, Balcells M, Canela-Garayoa R. 2013. H3PO4/metal halide induces a one-pot solvent-free esterification-halogenation of glycerol and diols. Rsc Advances 3, 8805-8810 ...

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Definitions of catalysis. What is catalysis: The action of a catalyst, especially an increase in the rate of a chemical reaction.. Synonyms: decay, dissolution, nucleation, oxygenase, catalytic, catalyze, esterification, cofactors, catalyst, catalyst, catalyzer, catalyses, hydrolysis, degeneration, heterogeneous catalysis, homogeneous catalysis

Liquid pharmaceutical compositions for administration to a mucosal surface, comprising a therapeutic agent and a pectin with a low degree of esterification are described. Such compositions gel, or can be adapted to gel, at the site of application in the absence of an extraneous source of divalent metal ions.

A robust unknown input multiobserver against disturbances for nonlinear systems: Experimental results on a batch esterification process. S. MEJDI, A. MESSAOUD and R. BEN ABDENNOUR ...

The incorporation and metabolism of both vesicle- and LDL (low-density lipoprotein)- derived [3H]cholesterol by LDL-receptor-negative fibroblasts were studied. Independent of the cholesterol source, free [3H]cholesterol was readily incorporated into the cells and was available for esterification. 7-Oxocholesterol stimulated both [3H]cholesterol incorporation, by increasing the exchange rate, and the subsequent esterification of it irrespective of the source of exogenous [3H]cholesterol. The 7-oxocholesterol-stimulated esterification of exogenously derived LDL free [3H]cholesterol was progesterone-sensitive and energy-requiring. ...

Deep eutectic solvents (DESs), as emerging green solvents, provide a new opportunity for the biorefinement of biomass, component extraction, and cellulose nanofibrillation. Herein, different carboxylic acid-based DESs were applied for preparation of cellulose nanofibers (CNFs) from cellulose raw materials accompanied by simultaneous esterification modifications of CNFs. The results showed that pretreatment of DESs combined with mechanical treatment can swell and esterify the cellulose materials, producing CNFs with widths less than 100 nm. The DES pretreatment temperature played important roles in the esterification modifications and nanofibrillation of cellulose. The esterification modifications of cellulose prevented the over-hydrolysis and dissolution of cellulose during the DES pretreatment, guaranteeing CNFs with high yields of 72 %-88 % and maintaining the cellulose I crystal structure. Moreover, the esterified CNFs were used as a reinforcement to prepare CNF-strengthened polylactic acid ...

TY - JOUR. T1 - Improved synthesis of fullerynes by Fisher esterification for modular and efficient construction of fullerene polymers with high fullerene functionality. AU - Zhang, Wen Bin. AU - He, Jinlin. AU - Dong, Xuehui. AU - Wang, Chien-Lung. AU - Li, Hui. AU - Teng, Fuai. AU - Li, Xiaopeng. AU - Wesdemiotis, Chrys. AU - Quirk, Roderic P.. AU - Cheng, Stephen Z.D.. PY - 2011/9/1. Y1 - 2011/9/1. N2 - For the first time, the scope of Fisher esterification has been extended to fullerene derivatives to improve the synthesis of alkyne-functionalized fullerenes (fullerynes) using 1-chloronaphthalene as a solvent and a specially-designed, home-made reactor to promote high yield. The design allows for higher solubility of fullerene derivatives and a continuous azeotropic distillation for the removal of water to drive the reaction to completion with yields ,90%. Both fullerynes (Fulleryne01 and Fulleryne02) were found to click to polymers, such as azide-functionalized poly(ε- caprolactone) ...

About this substance This section provides an overview of the calculated volume at which the substance is manufactured or imported to the European Economic Area (EU28 + Iceland, Liechtenstein and Norway). Additionally, if available, information on the use of the substance and how consumers and workers are likely to be exposed to it can also be displayed here.. The use information is displayed per substance life cycle stage (consumer use, in articles, by professional workers (widespread uses), in formulation or re-packing, at industrial sites or in manufacturing). The information is aggregated from the data coming from REACH substance registrations provided by industry.. For a detailed overview on identified uses and environmental releases, please consult the registered substance factsheet.. Use descriptors are adapted from ECHA guidance to improve readability and may not correspond textually to descriptor codes described in Chapter R.12: Use Descriptor system of ECHA Guidance on information ...

Background: The main goal of using statins is to reduce the level of plasma cholesterol, meanwhile they have a wide spectrum of actions. Objectives: To identify the effect of statins on fractional cholesterol esterification (FCE) as well as the complete profile of lipids and (apo)lipoproteins. Design and methods: In an age and sex matched case-control study, 400 subjects who were referred for coronary angiography were divided into two groups according using statins. Results: Total cholesterol was decreased significantly following treatment with statins (165.6 38.0 mg/dL vs. 205.3 48.4, p 0.001). About 90% of the reduction was occurred in nonHDL and 10% in HDL fraction. Reduction of nonHDL cholesterol (125.2 35.2 mg/dL vs. 162.8 45.2, p 0.001) occurred on both unesterified (52.4 21.5 mg/dL vs. 65.2 25.5, p 0.001) and esterified cholesterol (74.7 27.3 mg/dL vs. 96.6 34.1, p 0.001). But the decrease in HDL cholesterol (40.4 10.0 mg/dL vs. 42.3 9.9, p 0.079) happened exclusively in unesterified ...

Although it has been known for many years that excess lipid leads to insulin resistance, the precise molecular mechanisms linking lipid oversupply to defective insulin action are not fully elucidated. It has been suggested that enhancing fatty acid flux through the mitochondria in the absence of a concomitant metabolic remodeling of mitochondrial machinery may lead to deleterious effects on insulin action (38), whereas other studies report that increasing fatty acid oxidation can ameliorate insulin resistance by reducing intracellular lipid levels (22,39). Here, we report that a physiologically relevant increase in skeletal muscle CPT1 protein expression was sufficient to increase fatty acid oxidation and to prevent high-fat diet-induced fatty acid esterification into intracellular lipids, subsequently leading to enhanced muscle insulin sensitivity in high-fat-fed rats in the absence of major changes in markers of downstream capacity of the TCA cycle and ET/OxPhos pathways. The ...

TY - JOUR. T1 - Age-related changes in the rate of esterification of plasma cholesterol in Fischer-344 rats. AU - Carlile, Shirley I.. AU - Kudchodkar, B. J.. AU - Wang, C. S.. AU - Lacko, Andras G.. N1 - Funding Information: This work was supported by the National Institutes of Health (AG-03255, HL-27620). The Robert A. Welch Foundation (B-935) and the American Heart Association (82-1043). The authors thank Dr. W.J. McConathy for making the human plasma samples available and also thank Gayle White and Shirley Barnes for excellent secretarial assistance.. PY - 1986/1. Y1 - 1986/1. N2 - Plasma cholesterol and triglyceride levels and selected molecular species of plasma cholesteryl esters and triglycerides were determined in 6-, 12-, 15-, 18-, 21- and 24-month-old Fischer-344 rats. Lecithin:cholesterol acyltransferase (LCAT) activity was also determined using two independent methods utilizing endogenous and exogenous substrates. Plasma cholesterol levels increased up to 18 months of age and then ...

Offers ethoxylation, EO block co-polymerisation, PO block co-polymerisation, esterification, sulphation, phosphate easter, condensation, polymerisation, formulation, amides, imidazolines, distillation by Gujarat Chemicals in Surat, India.

Enzymatic transformations in organic solvents have received increasing attention over the past 10 years and lipases have become by far the most popular enzymes in this area.The initial aim of the research was to assess the effect of small modifications to the acyl donor in the transesterification reactions mediated by the Candida cylindracea lipase. 2.2.2-Trichloroethyl butyrate (TCEB) was used as a standard for the rate studies. In the event the acyl donor, trichloroethyl methoxyacetate (TCEMA), accelerated the transesterification reaction with hexan-1-ol by an order of magnitude over that with TCEB. This observation, and the absence of an acceleration with trichloroethyl methoxypropionate (and ethyl 2- fluorobutyrate over ethyl butyrate) suggested that the effect is due to the ~oxygen. A solvent activity profile indicated that the most hydrophobic solvents supported faster initial rates. This was attributed to the ability of the hydrophilic solvents to strip the hydrated water from the enzyme ...

Biodiesel is a renewable fuel produced when agricultural feedstocks such as vegetable oils, rendered animal fats, and used cooking oils are reacted with alcohol in the presence of a catalyst to form fatty acid esters, glycerin, and soap in a process known as transesterification. Because of economics and process considerations, methanol is the most commonly used alcohol in the transesterification p

Abstract. In the present work, the hydroxyl groups of HPMC, HPC and HEC polymers bonds with bioactive material naproxen drug by esterification process. (direct esterification and indirect esterification). The modified s polymers are characterized by some spectroscopic methods such as FTIR, UV, H1. NMR and C13. NMR. The degree of substitution (D.S) of the hydroxyl groups in suger molecule in polymer was determined in all cases.The hydrolysis of modified polymers is carried out in the heterogeneous phase in a buffer solution of pH (2.0, 7.4 and 9.0) at various temperatures (25, 37, and 45 Co). The amounts of released naproxen drugs were quantitatively determined by using calibration curve method. Biodegradation (in vitro degradation) of modification polymers is carried out by enzymatic cleavage (using lipase enzyme) at pH 7.4 (the human blood pH) and 37Co. The amounts of released naproxen were quantitatively determined by U.V visible spectrophotometry by using the usual calibration curve ...

This course unit detail provides the framework for delivery in 20/21 and may be subject to change due to any additional Covid-19 impact. Please see Blackboard / course unit related emails for any further updates.. Part A: Reactions of Molecules Relevant To Biological Systems. (Dr. Patrick OMalley and Prof. Jason Micklefield). The first 14 lectures will cover the basics of reaction mechanisms and describe a range of functional groups and their reactions. The lectures will illustrate the biological relevance of esterification, imine formation, amide bond formation, glycosylation, methylation, addition across double bonds, phosphate diester, and aromatic/heteroaromatic chemistry. Specific biological molecule classes used to illustrate these reaction types will include; peptides (peptide bond formation, methylation); lipids (esterification, electrophilic addition to alkenes); and carbohydrates (esterification and alkylation, imine formation, enolisation, glycosylation).. Part B: Analysing Molecular ...

7. The production method of N-isobutyl-2,6,8-decatrienamide production method according to claim 3, which comprises: (BI) preparing a hydroxyacetal represented by the formula (B2) by acetalization reaction and hydrolysis of an acyloxybutanal represented by the formula (B1) (acetalization step), ##STR00071## (in the formula (B1), Acyl represents an acyl group having from 2 to 5 carbon atoms, and in the formula (B2), RB1 and RB1 each independently represents an alkyl group having from 1 to 4 carbon atoms, or RB1 and RB1 may form a divalent carbon chain which may have a substituent group); (BII) preparing a sulfonic acid ester represented by the formula (B3) (sulfonic acid esterification step), ##STR00072## (in the formula (B2), RB1 and RB1 are as defined in the foregoing, and in the formula (B3), RB1 and RB1 each independently represents an alkyl group having from 1 to 4 carbon atoms, or RB1 and RB1 may form a divalent carbon chain which may have a substituent group, and RB2 represents an ...

In this work, the theoretical description of the 4- and 3-substituted-cinnamic acid esterification with different electron donating and electron withdrawing groups was performed at the B3LYP and M06-2X levels, as a two-step process: the O-protonation and the nucleophile attack by ethanol. In parallel, an experimental work devoted to the synthesis and characterization of the substituted-cinnamate esters has also been performed. In order to quantify the substituents effects, quantitative structure-property relationship (QSPR) models based on the atomic charges, Fukui functions and the Frontier Effective-for-Reaction Molecular Orbitals (FERMO) energies were investigated. In fact, the Fukui functions, ƒ+C and ƒ−O, indicated poor correlations for each individual step, and in contrast with the general literature, the O-protonation step is affected both by the FERMO energies and the O-charges of the carbonyl group. Since the process was shown to not be totally described by either charge- or frontier

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The main focus of this study is to mechanistically introduce a new qualitative and quantitative technique for mapping the lipid profile of a sectional brain via non-catalytic transesterification reaction (i.e., pseudo catalytic reaction in the presence of porous materials). One of the biggest technical advances achieved in this study is the qualitative and quantitative analysis of lipid from bovine brain in trace quantities in the magnitude of mu g via the non-catalytic pathway. Moreover, newly introduced derivatization in this work showed high tolerance against impurities (i.e., water and extractives ...

Indomethacin farnesil is a novel antiinflammatory prodrug of indomethacin designed to reduce the occurrence of side-effects by esterification of the carboxyl group on indomethacin with farnesol. Indomethacin farnesil is marketed as trade names Infree and Dialon. CAS: 85801-02-1 ...

TY - JOUR. T1 - Improvement in the secretory expression of recombinant Candida rugosa lipase in Pichia pastoris. AU - Kuo, Ting Chun. AU - Shaw, Jei Fu. AU - Lee, Guan Chiun. PY - 2015/12/1. Y1 - 2015/12/1. N2 - The yeast Candida rugosa can secrete a mixture of lipase isoenzymes (Lips), which have been widely applied in industry. Eight Lip genes (LIP1 to LIP8) have been identified and are expressed in Pichia pastoris. However, the expression level was not sufficient for economical industrial application. In this study, two combined processes of antibiotic selection and low-temperature culture efficiently elicited a high-level secretion of recombinant Lip2 in P. pastoris. The LIP2 gene copy number of the Pichia transformants was increased by sequential selections at gradually increasing Zeocin concentrations. After the first selection at 500 μg/mL of Zeocin, three clones (500-clones) with 2.4-fold to 5.8-fold improvement in Lip2 secretion were identified from 105 survival clones through lipase ...

This article reports an in situ transesterification/reactive extraction of Nannochloropsis occulata for fatty acid methyl ester (FAME) production using H2SO4, sodium dodecyl sulphate (SDS) plus H2SO4 and zirconium dodecyl sulphate (ZDS). A maximum 67 % FAME yield was produced by ZDS. Effect of inclusion of sodium dodecyl sulphate (SDS) in H2SO4 for FAME enhancement and water tolerance was also studied by hydrating the algae with 10 % - 30 % distilled water (w/w) dry algae. Treatment with SDS in H2SO4 increases the FAME production rate and water tolerance of the process. Inclusion of SDS in H2SO4 produced a maximum 98.3 % FAME yield at 20 % moisture in the algae. The FAME concentration began to diminish only at 30 % moisture in the algae. Furthermore, the presence of a small amount of water in the biomass or methanol increased the lipid extraction efficiency, improving the FAME yield, rather than inhibiting the reaction.

We have identified a novel tRNA methyltransferase in Saccharomyces cerevisiae that we designate Trm9. This enzyme, the product of the YML014w gene, catalyzes the esterification of modified uridine nucleotides, resulting in the formation of 5-methylcarbonylmethyluridine in tRNA(Arg3) and 5-methylcarbonylmethyl-2-thiouridine in tRNA(Glu). In intact yeast cells, disruption of the TRM9 gene results in the complete loss of these modified wobble bases and increased sensitivity at 37 degrees C to paromomycin, a translational inhibitor. These results suggest a role for this potentially reversible methyl esterification reaction when cells are under stress ...

This study explores the possibilities of using solid base catalysts, mainly hydrotalcites, for the transesterification of triglycerides (TAG) possessing alkyl groups in the range of C4-C18. The aim of the research is to design various types of layered double hydroxides (LDHs) formulated with different atomic ratio of M2+/Al3+ (M = Zn2+, Ni2+ and Mg2+), spanning from 1.5-4.0 via an alkali-free method. To enhance the physicochemical properties of the LDH, catalysts were calcined-rehydrated via gas-phase (GP), liquid-phase (LP), and hydrothermal (HTM) pathways. Extensive characterisation of both structural and base properties of these materials was conducted to provide a greater insight into the role of base sites for heterogeneously catalysed transesterification. Results showed HTM reconstructed method enhances the LDH reconstruction purity, surface area and basicity. A positive trend in initial rates was observed as GP , LP , HTM with reconstruction on conventional ZnAl LDH. Following this, the ...

TY - JOUR. T1 - Esterification of free fatty acids in adipocytes. T2 - A comparison between octanoate and oleate. AU - Guo, Wen. AU - Choi, Ji Kyung. AU - Kirkland, James L.. AU - Corkey, Barbara E.. AU - Hamilton, James A.. PY - 2000/7/15. Y1 - 2000/7/15. N2 - Medium-chain triacylglycerols (MCT) are present in milk, coconut oil and other foods, and are used therapeutically in special diets for certain disorders of lipid and glucose utilization. Recently, it has become apparent that MCT are not only oxidized in the liver, but are also present in lymph and fat tissue, particularly after chronic treatment. To evaluate the influence of MCT on metabolism in fat cells, we compared incorporation of octanoate and oleate into cellular triacylglycerols of 3T3-L1 adipocytes as well as their effects on preadipocyte differentiation. We found that less octanoate than oleate was stored and that more octanoate than oleate was oxidized. Octanoate was esterified to a greater extent at the sn-1,3 position of ...

Distilled glycerides are obtained through distillation of the system mono-diglycerides which is produced from the esterification reaction between a triglyceride with glycerol. In this work, monoglycerides (MG) and diglycerides (DG) are produced through lipase-catalyzed glycerolysis of soybean oil using Candida antarctica B in a solvent-free system. To separate the products of the reaction in order to obtain essentially MG and an oil of DG, it is necessary to use a suitable process in order to preserve the stability of the components and to keep the products free of inappropriate solvents. So, after 24 h of enzymatic reaction, the mixture of acylglycerols and fatty acids was distilled into a centrifugal molecular distiller, since it provides a free solvent and lower temperature environment to increase the desired product concentration. Starting from a material with 25.06% of triglycerides (TG), 46.63% of DG, 21.72% of MG, 5.38% of free fatty acids (FFA), and 1.21% of glycerol, the MG purity in ...

39] Martins A.B., da Silva A.M., Scheina M.F., Garcia-Galan C., AyubM.A.Z., Fernandez-Lafuente R., Rodrigues R.C., Comparisonof the performance of commercial immobilized lipases in thesynthesis of different flavor esters, J. Mol. Catal. B: Enzymatic,2014, 105, 18-25.[WoS][Crossref ...

References: Högberg, H.-E., Berglund, P., Edlund, H., FÀgerhag, J., Hedenström, E., Lundh, M., Nordin, O., Vörde, C., (1994) Catal. Today, 22, p. 591; Berglund, P., Holmquist, M., Hult, K., Högberg, H.-E., (1995) Biotechnol. Lett., 17, p. 55; Edlund, H., Berglund, P., Jensen, M., Hedenström, E., Högberg, H.-E., (1996) Acta Chem. Scand., 50, p. 666; Holmquist, M., HÊffner, F., Norin, T., Hult, K., (1996) Protein Sci., 5, p. 83; Grochulski, P., Bouthillier, F., Kazlauskas, R.J., Serreqi, A.N., Schrag, J.D., Ziomek, E., Cygler, M., (1994) Biochemistry, 33, p. 3494; Ahmed, S.N., Kazlauskas, R.J., Morinville, A.H., Grochulski, P., Schrag, J.D., Cygler, M., (1994) Biocatalysis, 9, p. 209; Allen, C.F., Kalm, M.J., (1963) Organic Syntheses, 4, p. 618. , in: R. Rabjohn (Ed.) Note 2, Wiley, New York; Berglund, P., Holmquist, M., Hedenström, E., Hult, K., Högberg, H.-E., (1993) Tetrahedron: Asymmetry, 4, p. 1869; Sonnet, P.E., (1987) J. Org. Chem., 52, p. 3477; Chen, C.-S., ...

Biodiesel is a clean and renewable resource that consists of mono-alkyl esters of long chain fatty acid, which could be obtained from the transesterification reaction of vegetable oils and animal fats with alcohols and catalysts. Biodiesel yield has typically been determined using expensive and laborious techniques. The attempt of this study was to examine the potential of quantifying the biodiesel conversion in real time using refractive index in transesterification process of canola oil with methanol and KOH. Biodiesel yields at five different mixing intensities and reaction times were measured using a refractometer. The measured results were then compared with analytical data obtained from thermogravimetric analysis (TGA) technique over a temperature range of 25℃ - 600℃. Experimental results indicated that the FAME conversions at different mixing intensity and reaction time measured from refractometer correlated well to the relative weight losses from TGA method with R2 = 0.93 (p ≤ 0.05);

The development of wood treatments is of increasing industrial importance. A novel technique for improving the properties of lodgepole pine and white pine through modification of the microstructure is described. The present investigation is devoted to the synthesis and determination of in situ parameters of citric acid and glycerol based polymers for wood impregnation. This solvent free approach is environmentally friendly and achieved through an esterification condensation reaction under acidic conditions. Crude glycerol and citric acid reactants were cross-linked via a curing process at 160 °C creating a polymer with only water as the byproduct. The ester bonds and crosslinking levels were controlled using different catalysts and citric acid contents and related to the reaction time and temperature. The nature of bonding within the polymers and at the wood cell walls was determined by FT-IR analysis. The thermal properties such as glass transition temperature (Tg) were studied using TGA/DSC ...

A simple method to overcome low equilibrium conversion in lipase catalysed resolution of alcohols by transesterification was developed. Ethyl octanoate was used as acyl donor as well as solvent and the reaction equilibrium was shifted by applying reduced pressure, forcing the co-product ethanol to evaporate during the reaction. Using a lipase from Candida antarctica 2-octanol, 1-phenyl ethanol, 1-cyclohexyl ethanol and trans-2-methylcyclohexanol were resolved in good optical and chemical yields.. ...

Interesterification involves the exchange and redistribution of acyl groups among triglycerides and can be divided into three groups according to the reaction type: acidolysis, alcoholysis and ester...

Background One of the most intriguing groups of enzymes, the feruloyl esterases (FAEs), is ubiquitous in both simple and complex organisms. FAEs have gained importance in biofuel, medicine and food industries due to their capability of acting on a large range of substrates for cleaving ester bonds and synthesizing high-added value molecules through esterification and transesterification reactions. During the past two decades extensive studies have been carried out on the production and partial characterization of FAEs from fungi, while much less is known about FAEs of bacterial or plant origin. Initial classification studies on FAEs were restricted on sequence similarity and substrate specificity on just four model substrates and considered only a handful of FAEs belonging to the fungal kingdom. Results Our study centers on the descriptor-based classification and structural analysis of experimentally verified and putative FAEs. 365 FAE-related sequences of fungal, bacterial and plantae origin were

In this paper the use of neural networks for fitting complex kinetic data is discussed. To assess the validity of the approach two different neural network architectures are compared with the traditional kinetic identification methods for two cases: the homoge In this paper the use of neural networks for fitting complex kinetic data is discussed. To assess the validity of the approach two different neural network architectures are compared with the traditional kinetic identification methods for two cases: the homogeneous esterification reaction between propionic anhydride and 2-butanol. catalysed by sulphuric acid and the heterogeneous liquid-liquid toluene mononitration by mixed acid. A large set of experimental data obtained by adiabatic and heat flux calorimetry and by gas chromatography is used for the training of the neural networks. The results indicate that the neural network approach can be used to deal with the fitting of complex kinetic data to obtain an approximate reaction rate ...

Independent of that is the simple electrostatic interaction of, these two groups. And now we have something, this molecule is a bit schizoid. And so you will have these two quasi-polar arrangements here and here, very ephemeral, that is lasting for a very short transient period of time. The lectures meet three times each week and recitations meet once a week. Download files for later. And they were analyzing the DNA sequences. Lecture 2: Discovery of Electron and Nucleus. You see it over here. by the way, as I mentioned last time, channels. Here we see a carbon bond to a hydroxyl here via this oxygen atom. And, in this case, what were referring to is the fact that if one were to reintroduce a water molecule into each of these three linkages, one, two and three, we would break the bond and cause this entire structure to revert to the two precursors that existed or preexisted prior to these three esterification reactions. And that really is stunning testimonial to the fact that under very ...

To overcome the drawbacks of homogeneous catalysts in the synthesis of trimethylolpropane trioleate (TMPTO), ionic liquids with different acidity were electrostatically immobilized onto SBA-15 to obtain heterogenized catalysts. The catalytic performan

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The VS ribozyme is one of the nucleolytic ribozymes, that catalyse the breakage of the phosphodiester bond at a particular site by a transesterification reaction in which the 2?-oxygen carries out a nucleophilic attack on the 3?-phosphorus. The reaction o

ObjectivesTo investigate the lipase-catalyzed synthesis of high purity sn-1/3 and sn-2 monoacylglycerols (1/3-MAG and 2-MAG) of different fatty acids (FAs).ResultsThe 1/3-MAGs of three FAs (16:0, 17:0, 16:1) were synthesized using lipase-catalyzed esterification of glycerol with FAs. The 2-MAGs were obtained from the ethanolysis of synthetic triacylglycerols using sn-1,3 regiospecific lipase. The effects of lipase types, substrate ratio, temperature, reaction time and lipase load on the MAG conversion were studied. Under the optimal conditions, high purities (96.74%, 95.44%, 92.96%) with acceptable isolated yields (51.00%, 54.28%, 46.00%) were obtained for 1/3-16:0-MAG, 1/3-17:0-MAG, and 1/3-16:1-MAG, respectively. For 2-16:0-MAG, 2-17:0-MAG, and 2-16:1-MAG, the purities were 92.64, 95.04, and 96.48%, with isolated yields of 50.64, 52.16, and 26.12%, respectively. The molecular structures of the synthetic compounds were confirmed by H-1 NMR, and MS and the melting points were characterized by ...

A novel series of imidazol-5-yl carbinols and their 4-chlorobenzoyl esters has been synthesized by the Grignard reaction and subsequent esterification. These compounds were screened for their antimicrobial activities in an agar diffusion assay. The compounds with C10 to C12-alkyl side chains displayed significant antimycotic activity.

Lipids are characterized by their amphipathic character. Because of this, they typically arrange in a bilayer configuration. The hydrophobic tails, however, also serve as a reservoir of metabolic energy, undergoing beta-oxidation in the Krebs cycle. In cells, lipids are stored in specialized organelles called lipid droplets (LDs) after esterification of their polar head with an additional hydrophobic chain. Thus, LDs can be considered as the dispersed phase of oil-emulsions-in-water, with the cytosol as the continuous phase. Our understanding of the molecular properties of LDs is very limited, and we are currently investigating how their function and behaviour is modulated by their unique chemical properties.. ...

Lipids are characterized by their amphipathic character. Because of this, they typically arrange in a bilayer configuration. The hydrophobic tails, however, also serve as a reservoir of metabolic energy, undergoing beta-oxidation in the Krebs cycle. In cells, lipids are stored in specialized organelles called lipid droplets (LDs) after esterification of their polar head with an additional hydrophobic chain. Thus, LDs can be considered as the dispersed phase of oil-emulsions-in-water, with the cytosol as the continuous phase. Our understanding of the molecular properties of LDs is very limited, and we are currently investigating how their function and behaviour is modulated by their unique chemical properties.. ...

Pieber, B.; Malik, J.; Cavedon, C.; Gisbertz, S.; Savateev, A.; Cruz, D.; Heil, T.; Zhang, G.; Seeberger, P. H.: Semi‐heterogeneous dual nickel/photo‐catalysis using carbon nitrides: esterification of carboxylic acids with aryl halides. Angewandte Chemie International Edition 58 (28), pp. 9575 - 9580 (2019 ...

Craveiro R., Menezes L., Durazzo L., Rocha A., Silva J. M., Reis R. L., Barreiro S., Duarte A. R. C., and Paiva A., Deep eutectic solvents for enzymatic esterification of racemic menthol, ACS Sustainable Chemistry Engineering, vol. 7, issue 24, pp. 19943-19950, doi:10.1021/acssuschemeng.9b05434, 2019. ...

The second half of orgo II will appeal to the biologists in the class (most of you!). We will discuss the physical and chemical properties of biomolecules such as amino acids, proteins, carbohydrates, lipids, steroids and nucleic acids including the chemical reactions in which they participate. Notably, many of the chemical reactions of biomolecules are similar to those we explored in the first half of the course. Their chemical reactivity will then allow us to discuss how each of these molecules is synthesized in living systems (biosynthesis) as well as how they are used in the material world (e.g., hydrolysis of lipids to make soap and transesterification of lipids to form biodiesel.) The course culminates with a discussion of how living systems metabolize some of these biomolecules to release energy. Here well focus on the organic transformations occurring in some of the enzyme-mediated processes. Metabolism is a rather innocuous word for a subject of great breadth; in other words, well ...