Convenient preparation of picolinyl derivatives from fatty acid esters

It is essential to have simple rapid methods for the determination of fatty acid structures. Traditionally, fatty acids are analysed by gas chromatography using their methyl ester derivatives (FAME). However, their corresponding mass spectra exhibit molecular ions but are usually devoid of ions indicative of structural features and, notably, the position of double bounds on the aliphatic chains [1]. In the most useful approach to structure determination, the carboxyl group is derivatised with a reagent containing a nitrogen atom. Recently, a convenient method for preparing picolinyl esters from intact lipids has been published [2]. However, some problems occurred in our laboratory when this method was used, leading to some modifications and optimisation. Thus, hexane and water have been added while sodium bicarbonate has been removed in order to lower contamination. Temperature and length of the reaction have then been optimised in order to get 100% derivatisation for different kinds of lipids (45 °C and 45 min for FAME). Finally, a comparison of the response factors has confirmed the better sensitivity of the picolinyl derivative against FAME (five times more).     

Electrochemical preparation of peroxodisulfuric acid using boron doped diamond thin film electrodes

We have investigated the electrochemical oxidation of sulfuric acid on boron-doped synthetic diamond electrodes (BDD) obtained by HF CVD on p-Si. The results have shown that high current efficiency for sulfuric acid oxidation to peroxodisulfuric acid can be achieved in concentrated H₂SO₄ (>2 M) at moderate temperatures (8-10 °C). The main side reaction is oxygen evolution. Small amounts of peroxomonosulfuric acid (Caro's acid) have also been detected. A reaction mechanism involving hydroxyl radicals, HSO₄⁻ and undissociated H₂SO₄ has been proposed. According to this mechanism electrogenerated hydroxyl radicals at the BDD anode react with HSO₄⁻ and H₂SO₄ giving peroxodisulfate.     

高单酯含量蔗糖酯的无溶剂制备

通过把微细蔗糖和硬脂酸甲酯制成粗分散体系(粒径小于10μm),用无溶剂法制备出了单酯含量高达79.8%的蔗糖酯。与其他典型的方法不同,该方法仅用4%的皂就可使硬脂酸甲酯转化率超过99%,大大减少了皂的用量。而且用相同量的皂就可制备出不同单酯含量的蔗糖酯,产率最高可达62.4%。考察了这种新反应体系的温度、催化剂量、皂的量和反应时间等不同条件下硬脂酸甲酯的转化率,还测定了不同单酯含量蔗糖酯的亲水亲油平衡(HLB)值、表面张力、界面张力和临界胶束浓度,揭示了它们之间的相互关系。     

The preparation of poly(methylene esters)

Conditions are described which allow the synthesis of poly(methylene terephthalate) from the reaction of methylene bromide with caesium terephthalate and though application of the procedure to prepare polymers from aliphatic dicarboxylic acids was unsuccessful, such polymers were synthesized from the analogous reaction with bromochloromethane.     

Nickel-catalysed electrochemical carboxylation of allylic acetates and carbonates

The electrochemical carboxylation of a series of allylic acetates and carbonates was carried out in the presence of CO₂ under atmospheric pressure, with a catalytic amount of nickel-bipyridine complex, to afford the corresponding β,γ-unsaturated carboxylic acids. In the absence of nickel catalyst, alcohols were obtained.     

The preparation of polyglycerol esters suitable as low-caloric fat substitutes

Medicinal research has linked dietary fats with such maladies as cancer, heart disease and stroke. The overconsumption of fats has been declared one of the major dietary health concerns in the United States by the Surgeon General. As a result, there is an increased awareness by consumers of their need to reduce the intake of calories derived from fat. The food industry has shown much interest in the development of substitutes for dietary fats and oils. To date, no substitute that can be used as a full fat replacement has entered the marketplace. Linear polyglycerols (LPGs) have been prepared by a proprietary polymerization process. Fatty acid esters prepared from LPGs were found to resist hydrolysis by digestive enzymes and were poorly absorbed in animal feeding tests. When esterified with fatty acids, LPG esters are similar to natural triglycerides in color, odor, taste and other physical characteristics. These properties make LPG oils good candidates for use in nonnutritive edible oil applications, particularly in uses that require stability at high temperatures.     

Electrochemical synthesis of peroxomonophosphate using boron-doped diamond anodes

A new method for the synthesis of peroxomonophosphate, based on the use of boron-doped diamond electrodes, is described. The amount of oxidant electrogenerated depends on the characteristics of the supporting media (pH and solute concentration) and on the operating conditions (temperature and current density). Results show that the pH, between values of 1 and 5, does not influence either the electrosynthesis of peroxomonophosphate or the chemical stability of the oxidant generated. Conversely, low temperatures are required during the electrosynthesis process to minimize the thermal decomposition of peroxomonophosphate and to guarantee significant oxidant concentration. In addition, a marked influence of both the current density and the initial substrate is observed. This observation can be explained in terms of the contribution of hydroxyl radicals in the oxidation mechanisms that occur on diamond surfaces. In the assays carried out below the water oxidation potential, the generation of hydroxyl radicals did not take place. In these cases, peroxomonophosphate generation occurs through a direct electron transfer and, therefore, at these low current densities lower concentrations are obtained. On the other hand, at higher potentials both direct and hydroxyl radical-mediated mechanisms contribute to the oxidant generation and the process is more efficient. In the same way, the contribution of hydroxyl radicals may also help to explain the significant influence of the substrate concentration. Thus, the coexistence of both phosphate and hydroxyl radicals is required to ensure the generation of significant amounts of peroxomonophosphoric acid.     

Synthesis of glycidyl esters

A novel method of synthesis of glycidyl carboxylates (2,3‐epoxypropyl carboxylates, RCOOCH₂CH‐CH₂O) has been developed by carrying out the reaction of epichlorhydrin with a carboxylic acid in the presence of chromium acetate catalyst and subsequent dehydrochlorination of the resulting mixture of chlorohydrin esters followed by their separation. © 1999 Society of Chemical Industry     

Alkali-catalyzed alcoholysis of crambe oil and camelina oil for the preparation of long-chain esters

The alcoholysis of crambe and camelina oils was carried out with oleyl alcohol, alcohols derived from crambe and camelina oils, and n-octanol using potassium hydroxide as catalyst to prepare alkyl esters. Conversions to alkyl esters were about 0% with oleyl alcohol, 20–45% with crambe and camelina alcohols, and 60% with n-octanol. The conversion to esters for crambe and camelina oil with oleyl alcohol and n-octanol increased with increasing molar excess of alcohol. Composition of the alkyl esters formed was as expected from the composition of the reaction partners. Presented as part of the doctoral thesis of Georg Steinke to the University of Münster, Münster, Germany.     

Enzymatic preparation of ricinoleic acid esters of long-chain monohydric alcohols and properties of the esters

Apart from the conventional chemical esterification process, long-chain alkyl ricinoleates also can be prepared by enzymatic esterification or by enzymatic alcoholysis with high yield and without undesirable side reactions. On sulfonation to the hydroxyl group, the alkyl ricinoleates produce surface-active compounds. The tetradecyl ricinoleate shows the best surface-active behavior and seems to be much better than that of sulfonated castor oil commonly known as “Turkey Red Oil”.     

Preparation of rapeseed oil esters of lower aliphatic alcohols

Rapeseed oil esters with lower aliphatic alcohols (C₁−C₄) were prepared in simple batch mode using an alkali (KOH) or acid (H₂SO₄) catalyst. The transesterification reaction conditions were optimized in order to obtain high yields of esters of the quality defined by standards for biodiesel fuels and for a short reaction time. Under these conditions it was possible to prepare only the methyl and ethyl esters catalyzed by KOH. Propyl and butyl esters were obtained only under acid catalysis conditions. The reaction catalyzed by H₂SO₄ was successfully accelerated using slightly higher catalyst concentrations at the boiling points of the alcohols used. The branched-chain alcohols reacted more slowly than their linear homologs, while t-butanol did not react at all. It was also possible to transesterify rapeseed oil using a mixture of alcohols characteristic of the end products of some fermentation processes (e.g., the acetone-butanol fermentation). A simple calculation was made which showed that, because of the higher price of longer-chain alcohols and because of the more intensive energy input during production the esters of these alcohols, they are economically unfavorable as biodiesel fuels when compared with the methyl ester.     

Properties of alkyl esters base on castor oil

Castor oil is a non‐traditional raw material for the preparation of methyl and ethyl esters of higher fatty acids as alternative fuels for diesel engines. Castor oil contains ricinoleic acid (12‐hydroxy octadecene acid) with a major share of about 90%. The article presents the parameters of castor oil‐based methyl esters (COME) and ethyl esters (COEE) defined by the standard EN 14 214. The densities of COME and COEE are higher than the limit defined by the standard EN 14 214. The viscosities are more than twice as high as the limit value. The cetane numbers are lower than defined by the standard EN 14 214. For the remaining parameters, COME and COEE meet, in principle, the standard EN 14 214. The presence of the free hydroxyl group has virtually no effect on the values of such parameters as carbon residue, filterability at low temperatures and oxidation stability, for which some influence was expected. The physicochemical parameters of the castor oil esters are discussed in comparison to the analogous esters of high‐oleic sunflower oil, which contain about 80% of oleic acid. Both the methyl and ethyl esters of high‐oleic sunflower oil meet the standard EN 14 214 in all prescribed parameters.     

硫代香叶酯的研制

讨论了以芳樟醇Linalool和硫代香叶醇为原料合成硫代香叶酯。并对合成硫代香叶酯的工艺条件进行优化，使硫代香叶酯的收率达到58％。     

咪唑啉酮氧苯氧羧酸酯类化合物的合成

用含二茂铁基的叠氮化物与三苯基膦反应制得膦亚胺,再与芳基异氰酸酯、取代酚发生串连aza-Wittig反应,合成了5个新的含二茂铁基的咪唑啉酮氧苯氧羧酸酯类化合物。用元素分析、IR、^1HNMR表征了它们的结构。     

Lipase-catalyzed alcoholysis of crambe oil and camelina oil for the preparation of long-chain esters

Crambe oil and camelina oil were transesterified with oleyl alcohol, the alcohols derived from crambe and camelina oils, n-octanol or isopropanol using Novozym 435 (immobilized lipase B from Candida antarctica), Lipozyme IM (immobilized lipase from Rhizomucor miehei), and papaya (Carica papaya) latex lipase as biocatalysts. The highest conversions to alkyl esters were obtained with Novozym 435 (up to 95%) in most cases, whereas Lipozyme IM and papaya latex lipase gave lower (40 to 50%) conversions. The conversions with long-chain alcohols (oleyl alcohol, crambe alcohols, and camelina alcohols) were higher (40 to 95%) than with medium-chain n-octanol (30 to 85%). Isopropyl esters of crambe oil and camelina oil were obtained with rather low conversions using Novozym 435 (<40%) and Lipozyme IM (about 10%) as biocatalysts, whereas with papaya latex lipase no isopropyl esters were formed. The conversions of crambe oil and camelina oil to oleyl and n-octyl esters using Novozym 435 as biocatalyst were hardly affected by the ratio of the substrates, but with Lipozyme IM the conversions to alkyl esters distinctly increased with an excess of alcohol substrate Presented as part of the doctoral thesis of Georg Steinke to the University of Münster, Münster, Germany     

Enzymatic preparation of polyethylene glycol esters of castor oil fatty acids and their surface-active properties

This study concerns the preparation and evaluation of nonionic surfactants prepared from polyethylene glycol (PEG) esters of castor oil fatty acid, a source of hydroxy fatty acid. A lipase-catalyzed esterification reaction has been employed to prepare PEG esters of hydroxy acid to overcome problems associated with chemical processes. Castor oil fatty acid (85% ricinoleic acid) was mixed with PEG of different molecular weight. Rhizomucor miehei lipase was added as catalyst (10% level) and the reaction was continued at 60°C under 2 mm Hg pressure for 360 min. Conversion of PEG to esters was in the range of 86–94%, depending on the molecular size of PEG. The products were isolated and examined for surface activity by surface tension measurement. Surface tension values measured at 25°C were about 36–37 dynes/cm.     

环境中PAEs的分析方法研究

邻苯二甲酸酯（phthalate esters,PAEs）是目前用量较大、应用范围较广的一类增塑剂,用以增加高聚物的可塑性。PAE通过范德华力同高聚物结合,容易逸出基体而通过各种迁移途径进入环境。PAEs具有致畸和致突变性,属环境内分泌干扰物。由于环境中PAEs的含量较低,通常采用预分离富集结合高端仪器的方法进行定量测定。本文综述了各种富集PAEs的技术以及检测方法,对于较适用环境检测手段的固相萃取-色谱测定过程做了重点介绍。     

Remarks on official methods employing boron trifluoride in the preparation of methyl esters of the fatty acids of fish oils

Some “official methods” for preparing methyl esters of the fatty acids from oils or fats may be referred to by users as the boron trifluoride (BF₃) method and invariably have two stages. The first stage, brief treatment with alkali [commonly NaOH in methanol (MeOH), sometimes NaOCH₃] and heat has been popularly described as a saponification step for over 30 yr. In fact, the disappearance of visible fat or oil is mostly transesterification, which can be accomplished in a few minutes under mild conditions. Free fatty acids (FFA) originally present, or produced by saponification, are not converted to methyl esters at this stage. The second stage, heating in BF₃-MeOH, has in practice been as short as 2 min. It can convert all FFA to methyl esters, but this step requires at least 30 min. Examples from the recent literature illustrate the necessity of extending the time for BF₃-MeOH transesterification of lipids or oils and methylation of FFA. No alkali transesterification is needed. Presented in part at the 88th Annual Meeting of the American Oil Chemists’ Society, Seattle, WA, May 1997.     

Enzymatic production of fatty acid alkyl esters with a lipase preparation from Candida sp. 99‐125

A lipase preparation developed from Candida sp. 99‐125 was used for fatty acid alkyl ester synthesis by both enzymatic esterification of fatty acids, and transesterification of oils and fats. The lipase preparation was chosen based on screening of lipases from commercial sources as well as those produced in the laboratory. The effects of enzyme dosage, solvent types, water absorbent additions, inhibition of short‐chain alcohols, alcohol and acid types, molar ratio of substrates, and reusability of the lipase preparation in esterification were studied. Degree of esterification between oleic acid and methanol under optimal conditions reached 92%. Purity of the methyl ester after washing with water and distillation was 98%. Half‐life of the lipase preparation was calculated to be approximately 340 h. For transesterification of rapeseed oil with the same lipase preparation, the amount of methanol and mode of methanol addition to the reaction were also conducted. Transesterification of the oil with stepwise methanol addition reached 83% after 36 h reaction time.     

手性溶剂萃取分离布洛芬对映体

研究了布洛芬对映体在含有疏水性L-酒石酸酯的1,2-二氯乙烷溶液及甲醇水溶液两相中的萃取分配行为,考察了不同烷基链长的L-酒石酸酯、D-酒石酸酯以及L-酒石酸酯的浓度、有机溶剂的种类和溶解布洛芬的甲醇水溶液浓度对分配系数K和分离因子α的影响。实验表明,L-酒石酸酯与布洛芬Ⅱ对映体形成的复合物稳定性比与布洛芬Ⅰ对映体形成的复合物稳定性要大,而D-酒石酸酯的萃取性能则与此相反,它与布洛芬Ⅰ对映体形成的复合物稳定性比与布洛芬Ⅱ对映体形成的复合物稳定性要大。有机溶剂的萃取性能为醇＞1,2-二氯乙烷＞烷烃,随着溶解布洛芬的甲醇水溶液中甲醇浓度的增大,分配系数K和分离因子α均降低,当甲醇的浓度为10%时,可以得到最佳的K和α。随着L-酒石酸酯浓度的提高,分配系数K和分离因子α先增大后减小,当L-酒石酸酯的浓度约为0.2 mol·L-1时,K和α达到最大值;L-酒石酸酯的碳链长度对分配系数K和分离因子α也有很大的影响。