从叔醇制备叔硫醇

实验室中合成叔硫醇缺少简便方法。用叔醇和氢溴酸与硫脲直接反应是目前采用的方法。Lee和Akerstrom曾用此法合成了叔硫醇,但碳原子数没超过七个。Sprague及Kresze分别用干燥氯化氢及盐酸代替氢溴酸也合成了叔硫醇,但产率不高。本文提出了用叔醇、硫酸与硫脲反应来制备叔硫醇的方法,并合成了六个叔硫醇。     

高碳三级硫醇的简便合成法

实验室合成三级硫醇缺少简便方法。Lee和Akerstrom改进反应条件,用下法合成了碳原子数从4到7的三级硫醇,这是目前合成三级硫醇常采用的方法。     

Microdetermination of certain mercaptans and carboxylic acids present in a mixture

An oxidimetric method is described for the determination of certain mercaptans based on their titration with standard potassium iodate in presence of 4–6 N hydrochloric acid. This procedure in conjunction with a method for determining mercaptans involving mercaptide formation with mercuric chloride can be used for the microanalysis of a mixture containing a mercaptan and a carboxylic acid.     

Semimicro determination of mercaptans with copper(II)

A rapid and precise titrimetric method for the determination of mercaptans on the semimicro scale is described. Samples dissolved in water, methanol. dimethylformamide or acetonitrile are treated with a measured excess of cupric sulphate. After 1 min, the excess of copper(II) is back-titrated with standard mercaptoacetic acid solution. At the end-point the violet complex first formed changes to a permanent yellow. The method is applicable to a variety of mercaptans and accurate to 0.2%. It is relatively free from interferences.     

Titrimetric determination of mercaptans with chloramine-T

Propyl mercaptan, allyl mercaptan, 2-mercaptoethanol, cysteamine hydrochloride, thio-p-cresol, 2-aminobenzenethiol, 2-mercaptopropionic acid and thioglycollic acid react with chloramine-T in 2:1 molar ratio in the presence of iodide, forming the corresponding disulphides. Mercaptans having a free beta-carbonyl group do not react quantitatively. The oxidation of the mercaptans is a function of time, and the corresponding sulphonic acids are formed on allowing them to stand with excess of chloramine-T. The oxidation to sulphonic acid is, however, instantaneous in the presence of iodine cyanide which acts as a catalyst and preoxidizer. This method is simple, accurate and rapid, and as little as 0.5 mg of the mercaptan can be determined with +/- 0.25% error.     

Selective complexometric determination of tin, with mercaptans as releasing agents

A method is proposed for selective complexometric determination of tin, mercaptans being used as releasing agents. To a solution containing tin and other cations, excess of EDTA is added and the surplus is back-titrated at pH 5-6 with lead nitrate (Xylenol Orange as indicator). Thioglycollic acid or mercaptopropionic acid is then added to decompose the tin-EDTA complex and the liberated EDTA is titrated with lead nitrate. The interference of various cations has been studied and the method has been employed for the estimation of tin in a variety of alloys.     

Analytical applications of mercaptan-carbon disulphide reaction: Determination of mixtures containing mercaptans

Summary A method is described for the determination of mercaptans by alkalimetric titration of trithiocarbonic acids formed through their reaction with carbon disulphide in tert.-butanol. The method has been applied to the analysis, on the same sample solution, of mixtures of mercaptans containing titrable hydrogen and those containing nontitrable hydrogen, mercaptans and alkali mercaptides, and mercaptans and mercaptopyrimidines.

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Analytische Anwendung der Merkaptan-Schwefelkohlenstoff-Reaktion: Bestimmung von Merkaptan in Gemischen

Zusammenfassung Ein Verfahren zur Merkaptanbestimmung durch alkalimetrische Titration der Trithiokohlensäure auf der Grundlage seiner Reaktion mit Schwefelkohlenstoff in tert. Butanol wurde beschrieben. Es eignet sich zur Bestimmung von Gemischen aus Merkaptanen mit titrierbarem Wasserstoff und solchen ohne titrierbaren Wasserstoff sowie von Merkaptanen und Merkaptiden, weiters von Merkaptanen und Merkaptopyrimidinen.

     

Addition of thiols at the double bond of methyl esters of 1-alkylcyclopropene-3-carboxylic acids

This is the first report of the addition of propyl and phenyl mercaptans at the double bond in the methyl ester of 1-methylcyclopropene-3-carboxylic acid with the formation of esters of thio-substituted cyclopropanecarboxylic acids in 67–72% yield. The addition of the thio group proceeds selectively at the least substituted atom of the double bond in the position anti to the methoxycarbonyl group.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 220–222, January, 1991.     

A Practical Preparation of Thiol Carboxylic Esters of 2-(Isoxazolyl) Acetic Acids

High yields of several thiolesters of 2-[3-(4-cyanophenyl)-4,5-dihydro-5-isoxazolyl]acetic acid are easily prepared from the corresponding oxoester by the reaction with trimethyl silylated mercaptan and aluminum chloride. The selection of mercaptans expands the previous scope of this synthetic method.     

Mercurimetrische Bestimmung von Mercaptanen in organischen L?sungsmitteln

Zusammenfassung Für die Bestimmung von aliphatischen und aromatischen Mercaptanen in organischen Lösungsmitteln wurde eine Methode vorgeschlagen, die auf einer Titration der in wäßrigem Ammoniak emulgierten Probe (vor dem Endpunkt wird Äthanol zugesetzt) mit o-Hydroxymercuribenzoesäure in Gegenwart von Thiofluorescein als Indicator beruht. Schwefel, Schwefelkohlenstoff und Disulfide beeinflussen die Ergebnisse nicht. Die Titration kann auch mit einer Lösung von p-Tolylquecksilberchlorid in Toluol ausgeführt werden. Für die Bestimmung von aliphatischen und aromatischen Mercaptanen nebeneinander wurde eine selektive Maskierung von aliphatischen Mercaptanen mit Acrylnitril vorgeschlagen.

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Summary A method is described for the determination of aliphatic and aromatic mercaptans in organic solvents. It is based on the titration of the emulsion formed with aqueous ammonia (before the end-point ethanol is added) with o-hydroxymercury benzoic acid using thiofluorescein as indicator. Sulphur, carbon disulphide, and other disulphides do not interfere. The titration with p-tolylmercury chloride is also possible. In order to determine aliphatic and aromatic mercaptans in presence of each other the use of acrylonitrile as selective masking agent for aliphatic mercaptans is suggested.

     

Extraction of Mercaptans from Light Hydrocarbon Mixtures with Aqueous Ammonia

Results of laboratory studies of the extraction of light mercaptans (methyl, ethyl, and propyl mercaptans) from hydrocarbons mixtures with a 25% aqueous solution of ammonia (caustic ammonia) are presented and discussed. It is shown that aqueous ammonia can in principle be used for controlled demercaptanization of light hydrocarbon fractions and liquefied hydrocarbon gases containing hydrogen sulfide and lower mercaptans. The advantage of this demercaptanization method over the conventional processes of alkali treatment is that there is no stage of oxidative catalytic regeneration of a spent alkali and there are no its highly toxic wastes, sulfurousalkaline waste waters. The regeneration of a spent (saturated with sulfurous compounds) aqueous ammonia can be comparatively easily performed by its heating (boiling), which leads to a hydrolytic decomposition of ammonium sulfides and mercaptides to release their constituent gases: hydrogen sulfide, mercaptans, and ammonia. Ammonia is recycled into the process as freshly prepared (regenerated) caustic ammonia.

     

Derivatization-Gas Chromatographic Determination Of Mercaptans

Abstract

After being precipitated as silver mercaptides, mercaptans were converted into their pentafluorobenzyl derivatives in high yields by reaction with sodium sulfide and then with pentafluorobenzyl bromide. The derivatives were analyzed down to sub-ppm levels by gas chromatography with a flame ionization detector. It is possible that the above method is developed for the trace analysis of mercaptans in environmental matrices.     

High conversion free-radical suspension polymerization: End groups in poly(methyl methacrylate) and their influence on the thermal stability

Suspension free-radical polymerization of vinyl monomers, carried out in the presence of alkyl mercaptans as chain-transfer agents, is analyzed. A model which accounts for the development with conversion of the polymer weight fractions having particularly tagged end groups, namely sulfur-containing and unsaturated end groups, is presented. The best current theories for diffusion-controlled polymerizations are included in the model. The sulfur content of poly(methyl methacrylate), determined as a function of conversion by a microcoulometric method, is in good agreement with the values predicted from polymerization kinetics. The rate of weight loss of the produced polymers is then related to the content of the unsaturated end groups. By comparing experimental thermal stability indexes (from thermogravimetry and isothermal heating experiments) to calculated polymer weight fractions, it is shown that the thermal stability of poly(methyl methacrylate) produced in the presence of alkyl mercaptans approximately depends on the square of the weight fraction of the polymer chains with an unsaturated end group.     

Surface functionalization and surface recognition: Plasmon optical detection of molecular recognition at self assembled monolayers

The synthesis of biotin- functionalized organic mercaptans and their chemisorption on gold surfaces is described. Biotin bound covalently to self assembled monolayers is recognized by streptavidin from aqueous buffer solutions. Spacer length and packing density of the biotin labels on the organic surface determine the docking kinetics. With a flexible and hydrophilic spacer very fast -diffusion controlled-docking is observed. As an alternative method of self assembly the spreading of organic mercaptans on water surfaces is established. Pressure-area diagrams of different functionalized mercaptans and disulfides are shown and their monolayer properties are discussed.     

Estimation of mercaptans with 1-chlorobenzotriazole

A simple but accurate potentiometric method for the estimations of mercaptans in 0.01M perchloric acid has been developed, based on their oxidation with 1-Chlorobenzotriazole. Quantitative oxidation solely to the disulphide stage is ensured by using critical amounts of methanol, acetonitrile and potassium iodide. Chloride, mercury(II) and copper(II) interfere. A back-titration procedure can also be used. The oxidation products have been identified.     

一种简单、温和、高效、无金属催化的双硫化物合成方法

以95%乙醇作为溶剂,在三溴苯乙酮的存在下硫酚或硫醇发生自身偶联反应生成双硫化合物。这是继传统方法之后一种温和、操作简单、绿色并且无金属催化的合成方法。在优化反应条件下考察了多种苯硫酚和硫醇类化合物,发现芳环上连有供电基团的化合物比含吸电子基团的能获得更高的产率,并且反应时间更短;同时,以脂肪族和杂环类化合物为底物也有较高的产率。     

A versatile approach to the synthesis of polyphosphazene derivatives via the thiol–ene reaction

The thiol–ene radical addition reaction has been successfully used to synthesize polyphosphazene derivatives. Poly[bis(allylamino)phosphazene] with pendant allyl groups was reacted with different thiol reagents under UV irradiation. These thiol reagents include 1‐pentanethiol, 3‐mercaptopropionic acid, 3‐mercapto‐1,2‐propane‐diol, and 2,3,4,6‐tetra‐O‐acetyl‐1‐thio‐β‐D ‐glucopyranose. ¹H NMR analyses confirm that the allyl polyphosphazene can be quantitatively modified by the mercaptans. In total, 100% conversion of the allyl groups was reached in <60 min toward the first three mercaptans, whereas about 80% conversion of the allyl groups was reached after 120‐min reaction toward the thioglucose. This method is a facile route for the synthesis of functional polyphosphazenes without the needs for protection/deprotection procedures. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Use of mercuric resins for selective abstraction of mercaptans in capillary gas chromatography

A small amount of mercuric non-porous resin placed in the liner of the injection splitter of a gas chromatograph retains mercaptans but allows other organic sulfur and non-sulfur compounds to be chromatographed normally: mercaptans in the gaseous state are retained by the mercuric resin. The method works well at 200°C but an increasing number of impurity peaks are observed as the temperature is increased to 250°C.     

Bestimmung der ?quivalentgewichte von Mercaptanen als Mercaptide der p-Mercuribenzoes?ure

Zusammenfassung Es wird eine neue Methode für die Bestimmung der Äquivalentgewichte von Mercaptanen vorgeschlagen, die auf der Titration mit p-ChloromercuribenzoesÄure in alkalischer Lösung in Gegenwart von Thiofluorescein als Indicator beruht. Das gebildete Mercaptid wird nach Zugabe von PhosphorsÄure abgetrennt und mit der ThioglykolsÄure-Methode auf den Quecksilbergehalt analysiert.

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Summary A new method is suggested for the determination of the equivalent weights of mercaptans based on the titration with p-chloromercuribenzoic acid in alkaline solution in the presence of thiofluorescein as indicator. The mercaptide formed is separated after addition of phosphoric acid and analysed for its mercury content by means of the thioglycollic acid procedure.

     

Spectroscopic study of dissolved organic sulfur (DOS): a case study of mercaptans

Sulfur compounds are often present in petrochemical wastewater and can be detected by UV spectrophotometry. This technique allows to point out specific absorptions of mineral sulfide and mercaptans and can be used for the determination of acidity constants. From a quantitative point of view, using a spectral deconvolution method, a specific determination of some mercaptans is obtained. Detection limits for ethanethiol and thiophenol are 0.7 and 2.5 mg l(-1), respectively.