Thiophenolate

Stern D A, Wellner E, Salaita G N, Laguren-Davidson L, Lu F, Batina N, Frank D G, Zapien D C, Walton N and Flubbard A T 1988 Adsorbed thiophenol and related oompounds studied at Pt(111) eleotrode by EELS, Auger-speotrosoopy, and oyolie voltammetry J. Am. Chem. Soc. 110 4885-93... 

Lover T efa/1997 Electrospray mass spectrometry of thiophenolate-capped clusters of CdS, CdSe and ZnS and cadmium and zinc thiophenolate complexes observation of fragmentation and metal, chalcogenide and ligand exchange processes Inorg. Chem. 36 3711... 

Alkyl mercaptans are partly soluble in solutions of caustic alkalis, but their salts are hydrolysed in dilute aqueous solution back to the free mercaptans. Thiophenols are soluble in alkah hydroxide solutions. Upon treatment with sodium, hydrogen is evolved. 

Thiophenols (or aryl mercaptans) are obtained by more vigorous reduction of sulphonyl chlorides (or of sulphinic acids), for example with zinc and dilute sulphuric acid, and are isolated by steam distillation ... 

This preparation must be carried out in the fume cupboard since thiophenol has an extremely unpleasant and repulsive odour the sub-stance should not be allowed to come into contact with the hands or clothing since the odour clings for days. 

Dilute sodium hydroxide solution. Carboxylic acids (RCOOH), sulphonic acids (RSO3H), phenols (ArOH), thiophenols (ArSH), mer-captans (RSH), imides (RCONHCOR), aryl sulphonamides (AxSOjNHj), arylsulphonyl derivatives of primary amines (AxSOjNHR), oximes (RCH=NOH), primary and secondary nitro compounds (RCH=NOOH and RjC=NOOH-oci forms), and some enols (e.g., of 1 3-diketones... 

The following classes of sulphur compounds occur in Solubility Groups II, III and VII sulphonic acids and derivatives, ArSO,OR sulphinic acids and derivatives, ArSOOR mercaptans, RSH thiophenols, ArSH sulphides or thioethers, RSR disulphides, RSSR sulphoxides, RR S->0 ... 

Aromatic sulphinic acids are oxidised by potassium permanganate.to sulphonio acids and are reduced by zinc and hydrochloric acid to thiophenols. 

Mercaptans and thiophenols (thiols). The thiols are generally liquids with penetrating and disagreeable odours, which persist even at extremely low concentrations in the air. They are soluble in dilute sodium hydroxide solution. Thiols are best characterised as the crystalline 2 4-dinitrophenyl thioethers or as the corresponding sulphones (see Section 111,168). 

Aryl sulfides are prepared by the reaction of aryl halides with thiols and thiophenol in DMSO[675,676] or by the use of phase-transfer catalysis[677]. The alkenyl sulfide 803 is obtained by the reaction of lithium phenyl sulfide (802) with an alkenyl bromide[678]. 

Sulfenylation of indoles can be carried out with sulfenyl halides[7], disulfides[7-9] or with A -methylthiomorpholine[10]. With disulfides the indoles are converted to lithium[8] or zinc[9] salts prior to sulfenylation. Thiophenols and iodine convert indoles to 3-(arylthio)indoles[l 1]. 

The higher reactivity of 2-halogenothiazoles with respect to halogenopyridines can be related to the different aromaticity of the two systems, less for thiazole than for pyridine, for example, the relatively stronger fixation of the tt bond in the thiazole than in the case of pyridine. As the data reported in Table V-1 (footnote a) indicates, the free thiophenol is more reactive than the thiolate anion toward the 2-halogenothiazoles. This fact should be considered when one prepares the thiazolyl sulfides. 

The role of the quaternization of the azasubstituent in the nucleophilic substitution at 2-halogenothiazoles is in fact emphasized by the reactivity of 2-halogenothiazoles with undissociated thiophenol (35), which proceeds faster than the corresponding reaction of 2-halogenothiazoles with thiophenolate anion, through the pathways shown in Scheme 6. Moreover, the 4-halogenothiazoles do not react with undissociated thiophenols, while the 5-halogenothiazoles react well (48). 

Regarding the substituent effect on reactivity of groups in positions 4 and 5 there is little information in the literature. The reactivity of halogen in position 5 seems to be increased when an amino group is present in position 2. Substitution products are easily obtained using neutral nucleophiles such as thiourea, thiophenols, and mercaptans (52-59). 

Stability. Diesel fuel can undergo unwanted oxidation reactions leading to insoluble gums and also to highly colored by-products. Discoloration is beheved to be caused by oxidation of pyrroles, phenols, and thiophenols to form quiaoid stmctures (75). Eventually, these colored bodies may increase in molecular weight to form insoluble sludge. 

Make acid yields coumaUc acid when treated with fuming sulfuric acid (19). Similar treatment of malic acid in the presence of phenol and substituted phenols is a facile method of synthesi2ing coumarins that are substituted in the aromatic nucleus (20,21) (see Coumarin). Similar reactions take place with thiophenol and substituted thiophenols, yielding, among other compounds, a red dye (22) (see Dyes and dye intermediates). Oxidation of an aqueous solution of malic acid with hydrogen peroxide (qv) cataly2ed by ferrous ions yields oxalacetic acid (23). If this oxidation is performed in the presence of chromium, ferric, or titanium ions, or mixtures of these, the product is tartaric acid (24). Chlorals react with malic acid in the presence of sulfuric acid or other acidic catalysts to produce 4-ketodioxolones (25,26). 

Similarly, thioalcohols and thiophenols react with isocyanates to form thiocarbamates. Although these reactions are generally found to be much slower than that of the corresponding alcohol, alkoxide catalysts have successfully been used to provide moderate levels of rate enhancement (68). 

The earliest reported reference describing the synthesis of phenylene sulfide stmctures is that of Friedel and Crafts in 1888 (6). The electrophilic reactions studied were based on reactions of benzene and various sulfur sources. These electrophilic substitution reactions were characterized by low yields (50—80%) of rather poorly characterized products by the standards of 1990s. Products contained many by-products, such as thianthrene. Results of self-condensation of thiophenol, catalyzed by aluminum chloride and sulfuric acid (7), were analogous to those of Friedel and Crafts. 

The process implications of equation 3 go beyond the weU-known properties (27—29) of NMP to faciUtate S Ar processes. The function of the aminocarboxylate is also to help solubilize the sulfur source anhydrous sodium sulfide and anhydrous sodium hydrogen sulfide are virtually insoluble in NMP (26). It also provides a necessary proton acceptor to convert thiophenol intermediates into more nucleophilic thiophenoxides. A block diagram for the Phillips low molecular weight linear PPS process is shown in Eigure 1. 

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