Biodiesel production using tetramethyl- and benzyltrimethyl ammonium hydroxides as strong base catalysts

In recent years, the acceptance of fatty acid methyl esters (biodiesel) as an alternative fuel has rapidly grown in EU. The most common method for biodiesel production is based on triglyceride transesterification to methyl esters with dissolved sodium hydroxide in methanol as catalyst. In this study, cottonseed oil and used frying oil were subjected to the transesterification reaction with tetramethyl ammonium hydroxide and benzyltrimethyl ammonium hydroxide as strong base catalysts. This work investigates the optimum conditions for biodiesel production using amine-based liquid catalysts. Biodiesel ester content was strongly related with the type of feedstock and the reaction variables, such as those of the catalyst concentration, methanol to oil molar ratio, and reaction time. The overall results suggested that the transesterification of cottonseed oil achieved high conversion rates with both catalysts, while the use of waste oil resulted in lower yields of methyl esters due to the possible formation of amides.     

Ring-Opening Amino Esterification of Cyclic Ketones to Access Distal Amino Acid Derivatives

This study developed a method of synthesizing distal amino acid derivatives by the ring-opening reaction of cyclic ketones, following the amino esterification functionalization of both terminals. To achieve this goal, we performed the ring-opening reaction of cyclic ketones with an aminating reagent and alcohol under metal- and photocatalysis-free conditions in a single step. The method directly afforded distal amino acid derivatives bearing C4−C6, C8, and C12 carbon main chains, such as γ, δ, and ϵ-amino esters. The obtained amino esters were simply transformed into amino acids by hydrolysis.     

Fatty Acid Methyl Esters with Two Vicinal Alkylthio Side Chains and Their NMR Characterization

The addition reaction of dimethyl disulfide (DMDS) to double bonds in alkenes and monounsaturated fatty acid esters in the presence of iodine or other catalysts to give bis(methylthio) derivatives has largely served analytical purposes in mass spectrometry with scattered reports on the addition of other disulfides to alkenes also existing. In this work, this iodine-catalyzed reaction was expanded to include the addition of other dialkyl disulfides (RSSR; R=ethyl, propyl, butyl, iso-propyl) besides DMDS to the double bonds in monounsaturated fatty acid methyl esters with 16, 18, 20, and 22 carbon atoms in the fatty acid chain to give the corresponding methyl 1,2-bis(alkylthio)alkanoates. The products are obtained in high to moderate yield after a facile purification procedure and are analytically characterized not only by mass spectrometry but also ¹H and ¹³C NMR. The threo and erythro diastereomers obtained from (Z) and (E) fatty acid methyl esters, respectively, can be easily distinguished by the NMR shifts of the protons and carbons in and close to the 1,2-bis(alkylthio) moiety. Various other effects in the NMR spectra are discussed. The 1,2-bis(alkylthio) derivatives of a symmetrical alkene, 7(E)-tetradecene, serve to confirm the NMR assignments besides NMR techniques such as 2D correlations and DEPT. The compounds may show properties of interest for various applications.     

微波辅射树脂催化合成L-氨基酸酯的研究

在微波辐射下,强酸性阳离子交换树脂为催化剂,一步酯化合成了8种空间位阻较高的L-氨基酸异丙酯和异丁酯,并用1HNMR和IR对其结构进行了表征。研究结果表明,微波辐射大大加速了酯化反应,所得8种酯的酯化收率均在50~70%之间。微波辐射反应所需时间大幅缩短,仅为常规加热时间的1/48~1/72,且反应物极性越大,反应时间缩短越明显。同时,就微波辐射功率、辐射时间及加热方式对酯化反应的影响进行了研究。     

微波辐射树脂催化合成L-氨基酸酯

在微波辐射下,强酸性阳离子交换树脂为催化剂,一步酯化合成了8种空间位阻较高的L-氨基酸异丙酯和异丁酯,并用1HNMR和IR对其结构进行了表征。研究结果表明,微波辐射大大加速了酯化反应,所得8种酯的酯化收率在47%~67%。微波辐射反应所需时间大幅缩短,仅为常规加热时间的1/48~1/72,且反应物极性越大,反应时间缩短越明显。同时,对微波辐射功率、辐射时间及加热方式对酯化反应的影响进行了研究。     

Characterization of some heated fat components

Substances produced at low levels in fat by heating were isolated and characterized. Partially hydrogenated soybean oil (Iodine Value 78) was heated at 182 C for 10, 8.5-hr, days with exposure to air. The oil was converted to ethyl esters, which were distilled and adducted with urea. The nonadductable fraction was subjected to chromatographic separations, and some of the components were purified sufficiently for chemical and spectroscopic characterization. Substances recognized include aromatic esters, saturated and unsaturated cyclic esters, ethoxyoctadecenoate, ethoxyhydroxyoctadecanoate, oxo-octadecanoate, oxo-octadecenoate, and cyclic hydroxy esters, all having 18 carbons in the acid chain. Presented at the AOCS Meeting, New Orleans, May 1967.     

Effect of food emulsifiers on crystal structure and habit of stearic acid

Several food emulsifiers have been found to serve as crystal structure modifiers for stearic acid crystallized from various organic solvents. Stearic acid that usually precipitates under appropriate crystallization conditions as the B- form is converted into the C- form when 1- 5% of sorbitan esters or ethoxylated sorbitan esters of fatty acids are present in the solution. Other emulsifiers such as polyglycerol esters, bdsubstituted monoglycerides and sucrose esters of fatty acids consisting of bulky hydrophilic groups are also effective emulsifiers in preserving the C- form of the crystallized stearic acid. The active emulsifiers modify the external crystal habit of stearic acid. Mass spectrograph analysis indicates that sorbitan monostearate (Span 60) is precipitated with the stearic acid.     

Determination of cyclic fatty acids by gas-liquid chromatography

A method is described to determine cyclic fatty acids in cyclic monomers by gas-liquid chromatography (GLC), which separates saturated straight-chain esters from cyclic esters. The content of cyclic esters can be determined by integration of the area on the chromatograph under the cyclic peaks. GLC was applied to cyclic monomers made from linseed oil and from linolenic acid. Samples of both hydrogenated and nonhydrogenated cyclic monomers were analyzed; however, more reliable results were obtained on the hydrogenated samples. The results show a standard deviation of 0.25 for linseed oil and 0.36 for linolenic acid. Accuracy of the analysis was established by comparing data with that obtained by crystallization. The GLC method is approximately three times faster. Presented at the AOCS meeting, New Orleans, La., 1962. A laboratory of the No. Utiliz. Res. & Dev. Div., ARS, U.S.D.A.     

胺基CO2固体吸附剂脱碳特性及SO2的影响

燃煤电厂烟气中存在的微量SO₂对胺基CO₂固体吸附剂的碳酸化反应及循环特性有不利影响。利用固定床反应器,针对采用溶胶凝胶法制备的胺基CO₂固体吸附剂的碳酸化特性及其在含SO₂气氛下的失效规律进行了实验研究,并结合红外光谱、有机元素分析、BET等测试手段,研究其失效机理。结果表明,所制备的胺基CO₂固体吸附剂在反应温度50℃时具有较好的碳酸化反应特性和循环特性。当反应气氛中存在SO₂时,由于生成了不可再生的亚硫酸/硫酸盐类物质而导致胺基活性位损失,孔隙结构发生变化,影响了吸附剂的脱碳性能,但适当提高反应温度可提高吸附剂的碳酸化反应竞争性。     

Electroflotation Studies on Cu,Ni, Zn,and Cd with Ammonium Dodecyl Dithiocarbamate

Abstract

The concentration of Cu, Ni, Zn, and Cd ions by electroflotation using the ammonium salt of dodecyl dithiocarbamic acid as an anionic collector is examined. Quantitative studies reveal better separation efficiency by this method as compared to column flotation using dodecyl dithiocarbamic acid ligand as a chelating surfactant.     

Vinyl esters of some aldehydic acid acetals

Vinylation of azelaaldehydic and brassylaldehydic acid cyclic acetals from ethylene glycol gave excellent yields of the vinyl esters. Under conditions of the vinyl exchange reaction used, acyclic acetals from monohydric alcohols cleaved to give enol-ethers as major, inseparable impurities. Radical-initiated polymerization of the pure vinyl esters of the aldehydic-acid cyclic acetals resulted in crosslinking when initiation was by either peroxide or azobis (isobutyronitrile). Presented at the AOCS Meeting, Toronto, October 1962. A laboratory of the No. Utiliz. Res. Dev. Div., ARS, USDA.     

Mehrfunktionelle N-Tenside. I. Nucleophile Substitutionen an Bischlornitrosoverbindungen 2. Reaktionen mit Thioharnstoff,substituierten Thioharnstoffen,Salzen und Estern von Dithiocarbaminsäuren und Mercaptoheterocyclen [1]

Polyfunctionalized N-Tensides. I. Nucleophilic Substitutions with Bischloronitroso Compounds. 2. Reactions with Thiourea, Substituted Thioureas, Salts and Esters of Dithiocarbamic Acid and Mercaptoheterocyclic Compounds Reaction of bischloronitroso compounds 1 with thiourea and substituted thioureas gives 2-aminothiazoles and 3-alkyl-2-iminothiazolines-(4). Ammoniumdithiocarbamate formes 4-thiazolinethiones-(2), and esters of the dithiocarbamic acids give 2-alkylmercaptothiazoles. N-substituted salts of dithiocarbamic acid and mercaptoheterocyclics react in boiling ethanol to form S-(β-oximinoalkyl)-dithiocarbamates 8 and in some cases 4-thiazolinthiones-(2) 9 .     

Enzymatic synthesis of astaxanthin n-octanoic acid esters

We examined the enzymatic synthesis of astaxanthin n-octanoic acid esters. Carriers for the immobilized enzyme and reaction conditions such as water content, reaction temperature, and time were examined using Candida cylindracea lipase (Lipase OF). Lipase OF) immobilized by a hydrophobic anion exchange resin (10% w/w content of lipase) gave the best yield in the esterification reaction of astaxanthin. Two milligrams of astaxanthin per 750 microL tri-n-octanoin (ca. 0.3%) was optimum because of the low solubility of tri-n-octanoin. The esters were obtained in a yield of 36.4% under the optimal reaction conditions.     

Synthesis of secondary ethers derived from meadowfoam oil

Secondary ethers can be obtained from meadow-foam-derived delta lactones or 5-hydroxy fatty acids by using Lewis or Brønsted acid catalysts in good yield (70–90%). The conversion of δ-lactone or 5-hydroxy fatty acid to 5-ethers is performed under atmospheric pressure between 67 and 125°C with 0.5–6.4 mole equivalents of acid catalyst in the presence of 2–40 equivalents of alcohol and a reaction time of 1–140 h. Acid catalysts include mineral acids, such as perchloric and sulfuric; Lewis acids, such as boron trifluoride; and heterogeneous catalysts, such as clays and ion-exchange resins. Primary alcohols, such as methanol, butanol, decanol, and oleyl alcohol, or branched-chain alcohols, such as 2-ethylhexanol, can be used to make secondary ether fatty esters. The 5-ether fatty esters and the process for their formation have not been previously known and appear to be limited to structures where stabilized cations can be formed. The novel ethers were fully characterized by nuclear magnetic resonance and gas chromatography-mass spectrometry.     

Synthesis of pinonic acid esters from ozonolysis of α-pinene

以天然产物松节油的主要成分α-蒎烯和醇为原料,二氯甲烷为溶剂,经臭氧氧化制得α-蒎烯臭氧化物,臭氧化物不加分离直接在三乙胺（TEA）催化下经乙酸酐重排（AA）裂解,一锅法合成了6种蒎酮酸酯类化合物。考察了乙酸酐用量、三乙胺用量、反应时间和反应温度等条件对蒎酮酸酯收率的影响,并通过正交试验对合成条件进行了优化。优化的实验条件为：nAA/nα-蒎烯 = 3.0∶1,nTEA/nα-蒎烯 = 0.75∶1,反应时间为60 min,反应温度为30 ℃,在该条件下合成的6种蒎酮酸酯收率均在60%以上,并采用1H NMR、13C NMR、IR、MS对6种化合物的结构进行了表征。该方法操作简便,条件温和,且收率高,是合成蒎酮酸酯类化合物的一种简易可行的方法。     

Highly Enantioselective Michael Addition of Cyclic 1,3‐Dicarbonyl Compounds to β,γ‐Unsaturated α‐Keto Esters

A highly enantioselective Michael addition of cyclic 1,3‐dicarbonyl compounds to β,γ‐unsaturated α‐keto esters catalyzed by amino acid‐derived thiourea‐tertiary‐amine catalysts is presented. Using 5 mol% of a novel tyrosine‐derived thiourea catalyst, a series of chiral coumarin derivatives were obtained in excellent yields (up to 99%) and with up to 96% ee under very mild conditions within a short reaction time.     

Observations on response factors for thermal conductivity detectors in GLC analysis of fatty acid methyl esters

Various correction factors have been proposed for quantitative analysis of fatty acid methyl ester mixtures by isothermal gas-liquid chromatography (GLC) employing thermal conductivity detectors in an effort to obtain more accurate values. These factors include multiplication of the area of each peak by the square root of the molecular weight of each component before calculating the percentage of each compound in the mixture or applying corrections for relative molar response for saturated esters and relative mass response for unsaturated esters. These proposed factors are not valid corrections for detector response but fortuitously are approximate compensations for lack of optimum operating conditions for each component. This is shown from the analysis of a number of standard fatty acid methyl ester mixtures by isothermal and programmed temperature GLC where the detector is maintained under identical conditions. Isothermal GLC requires different factors each time operating conditions are altered appreciably while proper temperature programming required little or no corrections depending on the particular mixture of methyl esters.     

以单体酸为原料制备生物柴油

研究了以单体酸为原料制备生物柴油的方法,反应以对甲苯磺酸为催化剂,单体酸与甲醇进行酯化反应获得脂肪酸甲酯。分别考察了酯化反应条件如甲醇与脂肪酸的摩尔比、反应时间、催化剂浓度以及反应温度对酯化率的影响。通过正交实验得到最佳酯化反应参数：醇酸摩尔比3∶1,反应时间3 h,对甲苯磺酸用量6%,反应温度60 ℃,该条件下单体酸酯化率达98.25%。实验制得的单体酸甲酯生物柴油的主要性能指标符合ASTM质量标准,并与0^#柴油性质接近。     

微通道中合成环氧脂肪酸甲酯

采用盐酸H2O2/HCOOH法,在微通道反应器内对不饱和脂肪酸甲酯进行环氧化反应。考察了双氧水用量、甲酸用量、反应温度及催化剂用量对反应的影响,得到最优的反应条件为:m(脂肪酸甲酯):m(甲酸):m(双氧水)=1:1.5:2,反应温度40℃,催化剂浓盐酸质量分数为3%(即浓盐酸质量占原料脂肪酸甲酯质量的百分数,下同),反应时间为110 s。在该条件下,产品环氧值为4.32%。     

Cationic activated monomer polymerization of heterocyclic monomers

In the first part of this review the meaning of activation is discussed and selected examples of polymerizaton processes in which activation of monomer is required prior to actual propagation are presented. In some systems, activation of monomer proceeds with such a strong interaction between an activator and monomer that a new chemical entity is derived from the monomer. To describe the mechanism of such a process, the term ‘Activated Monomer Mechanism’ has been coined.

The main part of the review is concerned with cationic Activated Monomer (AM) polymerization of cyclic ethers. In this process, cyclic ether is activated by formation of protonated species in the presence of a protic acid. Reaction of the protonated (activated) cyclic ether with hydroxyl group containing compounds leads to ring opening reforming the hydroxyl group. Several repetitions of such a reaction constitute a chain process. Thus, in AM polymerization of cyclic ethers hydroxyl group containing compounds act as initiator, protic acid is a catalyst, growing chain end is fitted with hydroxyl group and the charged species is a protonated monomer. The important feature of such a polymerization mechanism is that due to the absence of charged species at the growing chain end, back-biting leading to the formation of macrocyclics can be eliminated.

The mechanism and kinetics of AM polymerization of cyclic ethers is discussed and the approach allowing one to determine the rate constant for propagation involving activated monomer species is outlined. The application of the AM concept to the copolymerization of cyclic ethers as well as to the polymerization of monomers containing both initiating (hydroxyl groups) and propagating (cyclic ether) functions within one molecule are presented.

In the subsequent parts of the review, examples of cationic AM polymerization of other types of heterocyclic monomers, including cyclic acetals, cyclic esters (lactones), amines and amides (lactams), are given.

Finally, the polyaddition of oxiranes to derivatives of phosphoric acid is discussed. Although this system does not conform to the AM polymerization scheme, it bears formal resemblance to earlier systems in such a sense that the activation of the cyclic ether is required for the reaction to occur.