Formation of N- and O-methyl derivatives of lipids containing amino,amide or hydroxy groups by the pyrolytic reaction with trimethylsulfonium hydroxide

Base-catalyzed transesterification of acyl lipids with methanol in the presence of trimethylsulfonium hydroxide (TMSH) is an easy and convenient method for the preparation of fatty acid methyl esters for GC analyses. However, lipids containing functional groups such as amino, amide and hydroxy groups are converted in varying degrees to the corresponding N- and O-methyl derivatives by the pyrolytic reaction of TMSH occurring in the injector of the gas chromatograph. For example, lipids containing amino or amide groups are converted into the corresponding N-methyl and N,N-dimethyl derivatives, fatty acid ethanolamides to the corresponding N-methyl, O-methyl and N,O-dimethyl derivatives, whereas alkyl methyl ethers are formed from long-chain alcohols. Furthermore, 2-O- and 3-O-monomethyl ethers as well as 2,3-di-O-methyl ethers are formed from 1-O-alkylglycerols, methoxy fatty acid methyl esters from hydroxy fatty acids as well as steryl 3β-O-methyl ethers from cholesterol and other sterols. Since some of the mentioned artefacts may interfere with fatty acid methyl esters in GC separations the TMSH derivatization method is recommended only with caution for lipids containing amino, amide and hydroxy groups. The methylation reactions, which finally lead to the corresponding N-methyl, O-methyl, N,N-dimethyl or N,O-dimethyl derivatives of fatty acids and lipids may, however, be of some diagnostic value for the structural analysis of such lipids by GC/MS.     

Reaction of lipids containing hydroxy groups with trimethylsulfonium hydroxide: Formation ofO-methyl derivatives

Base-catalyzed transesterification of acyl lipids with trimethylsulfonium hydroxide (TMSH) is an easy and convenient method for the preparation of fatty acid methyl esters (FAME) for gas chromatography (GC) analyses. We have found, however, that lipids containing hydroxy groups are partially converted to the correspondingO-methyl ether derivatives which may interfere with FAME in GC separations. For example, long-chain alcohols are found to be converted to alkyl methyl ethers,rac-1-O-alkylglycerols to the corresponding 2-O-and 3-O-monomethyl ethers, as well as 2,3-di-O-methyl ethers, hydroxy fatty acids to methoxy FAME, and cholesterol to cholesteryl 3β-methyl ether. From our results, it is obvious that TMSH derivatization method is not recommended without limitation for lipids containing hydroxy groups; it may be, however, of some diagnostic value for the analysis of such lipids by GC/mass spectrometry.     

PVC modification with bifunctional thiol compounds

Summary The chemical modification of PVC with bifunctional thiol compounds is reported. Aliphatic as well as aromatic compounds were tested under different reaction conditions. The modified PVC's were studied by IR and H-NMR.     

Simultaneous derivatization of acyl and S-alkyl moieties of acyl thioesters by using trimethylsulfonium hydroxide for gas chromatographic analysis

The reaction of long-chain acyl thioesters, viz. lauric acid dodecyl thioester, 1,8-di-S-palmitoyl octanedithiol, and tristearoyl α-monothioglycerol, with trimethylsulfonium hydroxide in the presence of methanol leads to simultaneous derivatization of acyl moieties and S-alkyl moieties of acyl thioesters to the corresponding fatty acid methyl esters and methyl alkylsulfides, respectively. These derivatized products were analyzed by gas chromatographic technique.     

Preparation of gelatinous aluminium hydroxide from aqueous solutions of organic aluminium salts by reaction with alkali

The preparation of gelatinous aluminium hydroxide from aqueous solutions of the formate, citrate or tartrate of aluminium on addition of aqueous sodium hydroxide has been investigated under different conditions. The precipitates from aqueous solutions of aluminium formate consist of amorphous aluminium hydroxide, pseudoboehmite, bayerite, hydrargillite or their mixtures, depending on the condition of preparation. A mixed solution of aluminium citrate and sodium hydroxide yields no solid-phase product without aging on heating to enhance the hydrolysis of aluminium citrate. The resulting precipitate exists as pseudoboehmite, independent of the preparation conditions. In contrast, aluminium tartrate is not hydrolysed to precipitate aluminium hydroxide even by aging on heating.     

Rate characteristics for the reaction of carboxyl-modified polyamide with potassium hydroxide

Nylon 66 fiber, carrying 2.0 meq/g of carboxyl groups from radiation grafting of acrylic acid, was found to display chemical kinetics strongly first order with respect to the potassium hydroxide. The apparent rate constant k' remains nearly unchanged as the initial bath pH is varied from 8.3 to 10.5. At this point, the value of k' drops sharply, and continues to drop as the initial pH is increased. This discontinuity is attributed to a previously reported morphological transition indicated by a break in titration data at the corresponding equilibrium point of pH 9.2.     

连续精馏分离高温费托合成反应水中的含氧有机物

根据高温费托合成反应水的组成特点,采用连续精馏塔对反应水进行初分,以脱除大部分水和有机酸,同时,将非酸类含氧有机物提浓,利于后续化学品分离。首先采用NRTL热力学方法对流程进行了模拟,考察了塔板数、进料位置、回流比等工艺条件对分离结果的影响,得到了最优操作条件,然后采用实验室小型精馏塔对高温费托合成中试副产反应水进行了实验验证。结果表明:塔顶有机物质量分数可提高到75%以上,有机酸质量分数为0;塔釜采出物中非酸有机物质量分数小于0.01%,模拟最优条件为塔板数35块、进料位置为第15块,回流比为4。实验值与模拟值吻合良好。     

Solubility increase of coals by the reaction with alcohol — elucidation of reaction mechanism using model compounds

The reaction mechanism of coal-ethanol reaction was examined using model compounds: phenol, benzylphenylether, diphenylmethane and anthracene. The main reaction for these compounds was the splitting of ether bonds, ethylation of benzene nucleii, hydrogenation of aromatic nucleii and the splitting of methylene linkages. The most important reactions were the first two types. The splitting of ether linkages would reduce the molecular weight of coal and ethylation of aromatic rings would be favorable to the easy dissolution of coal in solvents.     

Homogeneous catalyzed reaction of carbon disulfide and o-phenylene diamine by tetrabutylammonium hydroxide in the presence of potassium hydroxide

The catalyzed reaction of o-phenylene diamine and carbon disulfide to synthesize 2-mercaptobenzimidazole (MBI) by tetrabutylammonium hydroxide (QOH; Q: (C₄H₉)₄N) was carried out in a homogeneous solution. A mixture of organic solvent (aprotic or protic) and water of an appropriate volume ratio acts as the homogeneous organic solution. The reaction is greatly enhanced either by tetrabutylammonium hydroxide or by tetrabutylammonium bromide in the presence of potassium hydroxide. Effects of the reaction conditions including the concentration of QOH, concentration of KOH, amount of CS₂, organic solvents, volume ratio of organic solvent to water, and temperature on the conversion of o-phenylene diamine are investigated in detail. An explanation is provided for the peculiar phenomena in studying the effects of the concentration of KOH on the conversion of o-phenylene diamine.     

Selective extraction of organic compounds from transesterification reaction mixtures by using ionic liquids

In this article, we describe assays carried out to determine the suitability of 13 ionic liquids based on 1‐n‐alkyl‐3‐methylimidazolium and n‐alkylpyridinium cations and a wide range of anions (hexafluorophophate, bis{(trifluoromethyl)sulfonyl}imide, tetrafluoroborate, methylsulfate, 2(2‐methoxyethoxy)ethylsulfate, ethylsulfate, n‐octylsulfate, dicyanamide, nitrate, tetrafluoroborate and chloride) to carry out the selective separation of the organic compounds involved in a transesterification reaction (butyl butyrate, vinyl butyrate, 1‐butanol, and butyric acid) from hexane solutions. The assayed ionic liquids were shown to be suitable solvents for the selective separation of the target compounds, the extraction process being controlled by the hydrophobicity of the compounds. The anion composition of the ionic liquid was seen to strongly influence the average extraction ratio, the highest value being reached with the chloride‐based ionic liquid. As regards the cation composition of the ionic liquids, it was seen that the average distribution ratio increased with decreasing length of alkyl chain. © 2010 American Institute of Chemical Engineers AIChE J, 2010     

Synthesis and characterization of calcium aluminate compounds from gehlenite by high-temperature solid-state reaction

The mineral transition mechanism and self-pulverization property of the sintered products in the Ca₂Al₂SiO₇-CaO system were systematically studied using pre-synthesized gehlenite determined by XRD, SEM, FTIR and particle size analyses. The minerals of Ca₁₂Al₁₄O₃₃, CaAl₂O₄, Ca₃SiO₅ and Ca₂SiO₄ are formed by the direct reactions of Ca₂Al₂SiO₇ with CaO. CaAl₂O₄ reacts with CaO to form Ca₁₂Al₁₄O₃₃ or Ca₃Al₂O₆, while Ca₃SiO₅ reacts with Ca₂Al₂SiO₇ to form Ca₂SiO₄ and calcium aluminate compounds. The sintered products mainly contain CaAl₂O₄, Ca₁₂Al₁₄O₃₃ and Ca₂SiO₄ at 1350?°C or above 1500?°C when the molar ratio of CaO to Al₂O₃ is 1.0. Increasing the sintering duration or the CaO consumption promotes the transition of Ca₂Al₂SiO₇ to Ca₂SiO₄ and calcium aluminate compounds when sintered at 1350?°C, which accordingly improves the self-pulverization property of the sintered products. The formed minerals of Ca₁₂Al₁₄O₃₃, CaAl₂O₄ and Ca₂SiO₄ transform into Ca₂Al₂SiO₇ again when the sintering temperature is between 1400?°C and 1450?°C, and the corresponding self-pulverization property of the sintered products deteriorates sharply.     

Modification of coking batch with pyrolytic products from low-metamorphic concentrates

The influence of volatile products from low-metamorphic concentrates coking coal is investigated thermogravimetrically. A promising approach to the industrial use of this effect is proposed.     

Synthesis of Imidazoles by reaction of N-benzylated amidines with carboxylic acid derivatives

2-Amino-N-heterocycles, such as 2-aminopyridine 7 or 2-aminobenzimidazole 16 as well as benzamidines 19 possessing a N-(4-nitrobenzyl)-substituent react as N-C-N-C-synthons with formamide chlorides 5 , formamide acetals 2 or acetic anhydride (C₁-building blocks) with formation of imidazole compounds 9 , 17 or 22 , respectively in the presence of triethylamine. In some cases, intermediate N-acetylation ( 20 ) or N-formylation products 21 are isolated.     

乙醇溶剂中硝酸银与氢氧化钠的反应机理

在乙醇溶剂中制备纳米Ag2O时,发现有纳米Ag2O和纳米Ag2种产物,进而通过XRD对其反应机理进行了研究。实验结果和理论分析表明,溶剂对制备纳米氧化银有很大影响,在乙醇溶剂中不能制备出纯的纳米氧化银;其反应机理为该反应首先是银离子与氢氧根离子反应生成氧化银沉淀,氧化银在碱性条件下将溶剂乙醇氧化为乙醛,而自身被还原为单质银;生成的乙醛又将银离子和氧化银还原为单质银,从而导致产物既有纳米氧化银又有纳米银;其中碱性介质是氧化银将乙醇氧化为乙醛的催化剂。     

On the mechanism of catalysis of the Boudouard reaction by alkali-metal compounds

The mechanism of catalysis of the Boudouard (C-CO₂) reaction by the alkali-metal compounds appears to involve gaseous intermediates M(g), CO(g) and CO₂(g) where M(g) may be Li, K, Na, etc. The cyclical mechanism M(g)→ M₂CO₃→ M(g) withstood the rigorous thermodynamic analysis presented here and may be regarded as the most likely mechanism. Detailed calculations showed that formation of intercalation compounds of the type C_2nM is not very likely except at very high temperatures (1400 K and above) and under nearly pure CO environments. Thus the likelihood of intercalation compound mechanism being valid is not substantial except under stringent conditions as noted. The electrochemical mechanism probably operates parallel to the cyclic mechanism; and its relative contribution to the overall reaction is not known at this time.     

The effects of potassium and rubidium hydroxide on the alkali-silica reaction

Expansion of mortar specimens prepared with an aggregate of mylonite from the Santa Rosa mylonite zone in southern California was studied to investigate the effect of different alkali ions on the alkali-silica reaction in concrete. The expansion tests indicate that mortar has a greater expansion when subjected to a sodium hydroxide bath than in a sodium-potassium-rubidium hydroxide bath. Electron probe microanalysis (EPMA) of mortar bars at early ages show that rubidium ions, used as tracer, were present throughout the sample by the third day of exposure. The analysis also shows a high concentration of rubidium in silica gel from mortar bars exposed to bath solutions containing rubidium. The results suggest that expansion of mortar bars using ASTM C 1260 does not depend on the diffusion of alkali ions. The results indicate that the expansion of alkali-silica gel depends on the type of alkali ions present. Alkali-silica gel containing rubidium shows a lower concentration of calcium, suggesting competition for the same sites.     

Simultaneous multiwavelength study of the reaction of phenolphthalein with sodium hydroxide

A photodiode array (PDA) spectrophotometer was used to study the fading reaction of phenolpthalein in dilute sodium hydroxide solution. The principal component analysis (PCA) method was employed to identify the number of light absorbing species in the kinetics system. The target factor analysis (TFA) procedure, coupled with the Broyden-Fletcher-Goldfard-Shanno (BFGS) optimization method, was applied to the observed data to deduce the rate constants and the concentration-time profile of the reaction. The internal referencing method was shown to be essential in improving the quality of data obtained by a single beam PDA spectrophotomer.     

Reactive dyes for cellulose. The reaction of alkoxychlorotriazinyl dyes with hydroxide ion

A Series of model alkoxychlorotriazinyl reactive dyes has been synthesised. Each compound, in turn, has been hydrolysed in dilute sodium carbonate solution and product ratios and rates of reaction determined. It has been found that the nature of the alkoxy group significantly influences the course and rate of the reaction.