Transmission of dipolar substituent effects: ionization of a series 3-(7-substituted-1-naphthyl) propynoic acid (E)-3-(7-substituted-1-naphthyl) propenoic acids and their Esterification with Diazodiphenylmethane

Alkaline hydrolysis rates coefficients for the series of methyl 3-(7-substituted-1-naphthyl) propynoate was calculated in 70%v/v dimethylsulphoxide-water at various temperatures (25,30,40, and 50̊ C). The pKa values of 3-(7-substituted-1-naphthyl) propynoic acid and (E)- 3-(7-substituted-1-naphthyl) propenoic acid calculated in 80%w/w 2-methoxyethanol-water at room temperature (25.0̊ C). logk2 of esterification rate coefficients for 3-(7-substituted-1-naphthyl) propynioc acid and (E)-3(7-substituted-1-naphthyl) propenioc acid with DDM have been measured at 30.0̊ C. Reversed substituent dipolar effects were found in the ionization reaction. In the esterification reaction with DDM the result show similar but reduced substituted effects. Rate retardations was found in the alkaline hydrolysis. It could be result from steric effect or reversal of substituent dipolar effect with a combination of steric effect.

PERSPECTIVE SEARCHES OF MEDICINAL PLANT RAW MATERIALS AS SOURCE OF POLYSACCHARIDES

The purpose of the conducted researches was studying of cones of a pine ordinary as source of polysaccharides in complex processing of raw materials. Cones of a pine ordinary were assembled during pollination. For the purpose of development of complex processing of raw materials researches on studying of the cones which remained after receiving pollen are conducted. Researches showed prospects of use of cones of a pine ordinary as source of polysaccharides after receiving pollen. The pectin content in ordinary pine cones, established by the oxalate method, was 1,2 ± 0,1%. Qualitative determination of pectin is proposed by colour reaction with solution of carbazole with alcohol 0,5%. Reaction with 10% lead (II) basic acetate was also used to identify pectin. One indicator of the detoxifying activity of pectin is the degree of esterification (ratio of esterified and free carboxyl groups). Low esterified pectins (esterification rate below 50%) are used as detoxicant. Important is the fact that the complex processing of ordinary pine cones will make it possible to obtain pectin actually from pollen production waste. In the developed scheme of complex processing of ordinary pine cones for hydrolysis-extraction of pectin-high substances from raw materials, it is proposed to use citric acid solution with pH 1,8-2,0. Methods for identifying and quantifying pectin in an object are valid. As a result of all the studies, a method was developed for producing pectin from ordinary pine cones in the complex processing of raw materials, the content of which was 1,2±0,1%, and the degree of esterification 13,20 ± 0,5%. The results of the conducted studies showed that the content of tannins in the studied raw materials of pine cones was 0,66±0,02%. As a result of all studies, a method of producing pectin from ordinary pine cones in complex processing of raw materials has been developed. The obtained results make it possible to recommend the obtained pectins as an effective detoxifying agent and a source of polysaccharides, tannins.

Preparation of Fe3O4@SiO2–ZnO catalyst and its catalytic synthesis of rosin glycol ester

In order to solve the problems of low recovery, low availability, and high cost in the synthesis of rosin glycol ester, a series of supported ZnO magnetic catalysts were prepared with Fe3O4 as the magnetic center, and their structures and compositions were characterized by TEM, XRD, and XPS. Through screening, the results show that Fe3O4@SiO2–ZnO has the best catalytic effect, far better than other catalysts, and has good stability. At the same time, the effects of zinc source and its load and different reaction conditions on the synthesis of rosin glycol ester were also investigated. The results showed that: When zinc chloride was used as zinc source, theoretical loading of zinc source was 0.45 g, reaction temperature was 270°C, reaction time was 5 h, and catalyst dosage was 0.2 g, the esterification rate of rosin-glyceryl ester was 87.2% and acid value was 26.5 mg KOH g−1.

Prediction of esterification rate constants for secondary alkan-2-ols based on one- and two-parameter Taft equations

Equilibrium constants and reaction rate constants for the esterification of secondary alkan-2-ols with acetic acid were measured at 60°C in 1,4-dioxane. Taft coefficients, as single parameter (without inductive effects), and two-parameter correlation (including inductive and steric effects), of the measurements were used for the prediction of esterification rate constants for secondary alkan-2-ols with monocarboxylic acids. For this prediction, previously observed results of linear correlation of rate constants for the esterification of propan-1-ol with monocarboxylic acids measured under identical experimental conditions were applied. Two parameter Taft equations for the correlation of secondary alkan-2-ols and for monocarboxylic acids were combined, resulting in an overall correlation equation usable for the prediction of reaction rates for secondary alkan-2-ols with any monocarboxylic acid. This equation was experimentally verified for the esterification of three randomly chosen alkan-2-ols with three randomly chosen monocarboxylic acids.

Synthesis of lutein esters using a novel biocatalyst of Candida antarctica lipase B covalently immobilized on functionalized graphitic carbon nitride nanosheets

The functionalized graphitic carbon nitride nanosheets (g-C3N4-Ns) as the immobilized carrier for the accommodation of Candida antarctica lipase B (CALB), which obtains the highest esterification rate (92%) in lutein esters synthesis.

Study on optimum synthesis of ethyl cyanoacetate

Ethyl cyanoacetate is an important chemical intermediate and has been used widely. Ethyl cyanoacetate was prepared by esterification of cyanoacetic acid and absolute ethanol with mixed catalyst (the same proportion of silicotungstic and p-toluene sulfonic acid as catalyst). The influence factors of the amount of catalyst, n(cyanoacetic acid): n ( absolute ethanol), reaction time and reaction temperature on the esterification rate was investigated by orthogonal experiment of four factors and three levels. The product was analyzed by gas chromatography to determine the optimum reaction conditions.

Optimization and kinetic study of methyl laurate synthesis using ionic liquid [Hnmp]HSO 4 as a catalyst

Methyl laurate was synthesized from lauric acid (LA) and methanol via an esterification reaction using ionic liquids (ILs) as catalysts. The efficiencies of three different catalysts, 1-methylimidazole hydrogen sulfate ([Hmim]HSO 4 ), 1-methyl-2-pyrrolidonium hydrogen sulfate ([Hnmp]HSO 4 ) and H 2 SO 4 , were compared. The effect of the methanol/LA molar ratio, reaction temperature, reaction time and catalyst dosage on the esterification rate of LA was investigated by single-factor experiments. Based on the single-factor experiments, the esterification of LA and methanol was optimized using response surface methodology. The results showed that the most effective catalyst was the IL [Hnmp]HSO 4 . The optimal conditions were as follows: [Hnmp]HSO 4 dosage of 5.23%, methanol/LA molar ratio of 7.68 : 1, reaction time of 2.27 h and reaction temperature of 70°C. Under these conditions, the LA conversion of the esterification reached 98.58%. A kinetic study indicated that the esterification was a second-order reaction with an activation energy and a frequency factor of 68.45 kJ mol −1 and 1.9189 × 10 9 min −1 , respectively. The catalytic activity of [Hnmp]HSO 4 remained high after five cycles.

Atherogenic Impact of Lecithin-Cholesterol Acyltransferase and Its Relation to Cholesterol Esterification Rate in HDL (FERHDL) and AIP [log(TG/HDL-C)] Biomarkers: The Butterfly Effect?

The atherogenic impact and functional capacity of LCAT was studied and discussed over a half century. This review aims to clarify the key points that may affect the final decision on whether LCAT is an anti-atherogenic or atherogenic factor. There are three main processes involving the efflux of free cholesterol from peripheral cells, LCAT action in intravascular pool where cholesterol esterification rate is under the control of HDL, LDL and VLDL subpopulations, and finally the destination of newly produced cholesteryl esters either to the catabolism in liver or to a futile cycle with apoB lipoproteins. The functionality of LCAT substantially depends on its mass together with the composition of the phospholipid bilayer as well as the saturation and the length of fatty acyls and other effectors about which we know yet nothing. Over the years, LCAT puzzle has been significantly supplemented but yet not so satisfactory as to enable how to manipulate LCAT in order to prevent cardiometabolic events. It reminds the butterfly effect when only a moderate change in the process of transformation free cholesterol to cholesteryl esters may cause a crucial turn in the intended target. On the other hand, two biomarkers – FERHDL (fractional esterification rate in HDL) and AIP [log(TG/HDL-C)] can offer a benefit to identify the risk of cardiovascular disease (CVD). They both reflect the rate of cholesterol esterification by LCAT and the composition of lipoprotein subpopulations that controls this rate. In clinical practice, AIP can be calculated from the routine lipid profile with help of AIP calculator www.biomed.cas.cz/fgu/aip/calculator.php.