2.5- dimercapto-l,3,4-thiadiazole

Dimercapto-l,3,4-thiadiazole derivatives, accelerated by amines, are used to cross-link chlorinated polyethylene. Polyisobutylene containing brominated i ra-methylstyrene cure functionahty can be cross-linked in polymer blends with dimercapto-1,3,4-thiadiazole derivatives accelerated with thiuram disulfides. Trithiocyanuric acid is suggested for use in polyacrylates containing a chlorine cure site and in epichlorohydrin mbbers. 

Curing Systems. The most commonly used vulcanizing agent for the polyethers not containing AGE, that is, ECH and ECH—EO, is 2-mercaptoimidazoline, also called ethylenethiourea [96-45-7]. Other commercially appHed curing agents include derivatives of 2,5-dimercapto-l,3,4-thiadiazole, trithiocyanuric acid and derivatives, bisphenols, diamines, and other substituted thioureas. 

Bismuthiol I (2,5-dimercapto-l,3,4-thiadiazole) potassium salt [4628-94-8] M 226.4, m 275-276 (dec), pKes,(I) 4.1. Usually contaminated with disulfide. Purified by crystn from EtOH. Reagent for detection of Bi,Cu, Pb and Sb. 

High-vacuum pyrolysis of 2,5-dimercapto-l,3,4-thiadiazole 34 and 2-mercapto-5-methyl-l,3,4-thiadiazole 9 performed between ambient and 800 °C gave products that were trapped by matrix-isolation techniques and characterized by IR spectroscopy. Pyrolysis of the dimercaptothiadiazole 34 gave HNCS, CS2, and HCN (Equation 2), whereas the thiadiazolethione 9 showed a more complex fragmentation pattern forming HNCS, CH3NCS, HCN, and CS2 (Equation 3) <2002J(P2)1620>. 

Iv) Thiadiazoles. The thiol-thione tautomerism of some thiadiazoles, such as 2,5-dimercapto-l,3,4-thiadiazole (DMTD) and related compounds, has attracted some attention because these compounds are of potential use in the production of antiwear additives for engine lubricating oils. 

The polymer-templated OMSs such as SBA-1545 possess pores about 8-12 nm, which are more spacious and can be decorated with more complex ligands. The SBA-15 sample studied exhibited ordered mesopores about 10 nm, and irregular micropores in the mesopore walls as shown in Figure 1. Initially chloropropyl-SBA-15 material was obtained and subsequently grafted with 2,5-dimercapto-l,3,4-thiadiazole ligand16 (OMM-3 material in Figure 1). These... 

O. Olkhovyk and M. Jaroniec, Ordered mesoporous silicas with 2,5-dimercapto-l,3, 4-thiadiazole ligand, high capacity adsorbents for mercury ions, Adsorption (2005) in press. 

Dichloro- and 2,5-dimercapto-l,3,4-thiadiazole, under the same conditions, give only (82). These rearrangements can also take place under acidic conditions. Treatment of... 

Sulfonic acids of simple 1,3,4-thiadiazoles appear not to have been prepared. The dipotassium salt of the 2,5-disulfonic acid was synthesized as early as 1899 by Busch and Ziegele by oxidation of the dipotassium salt of 2,5-dimercapto-l,3,4-thiadiazole with potassium permanganate. In the same way Petri and Glemser prepared 5-hydroxy-2,2 -azo-l,3,4-thiadiazole-5 -sulfonic acid dipotassium salt (125) from 2,2 -azo-l,3,4-thiadiazoline-5(4)-thione (76). 

Due to the electron attraction of the ring, the NH groups in amido-thiadiazoles and thiadiazolylhydrazones (54) have weakly acidic character. Potential mercapto compounds have distinctly acidic properties, and 2,5-dimercapto-l,3,4-thiadiazole and its 4-sub-stituted derivatives are strong acids. The pK and some pKn values of these compounds are found in Table III. 

Potential 2-hydroxy- and 2-mercapto-l,3,4-thiadiazoles have been examined both by infrared and by ultraviolet spectra in the solid state and in solution by Sheinker et They concluded that these compounds exist in the 2-oxo and 2-thione forms, respectively. To 2,5-dimercapto-l,3,4-thiadiazole the 2-mercapto-5-thione structure (155) was given. The structure of this compound has been the subject of some controversy. Stanovnik and TiSler have added some valuable arguments to the discussion. They measured the pKfl values of 155, its iV-methyl, iV -phenyl, and iV -phenyl-/S-methyl derivatives (156), and of the conjugate acids of these and the S-methyl derivative (pKn ) (Table III). In all compounds 156 with R = H, the infrared spectrum showed an absorption band near 2300 cm characteristic of the SH group. They also had pK i values near —1.5, Avhich in connection with the infrared evidence was taken as characteristic of an SH group in this situation. Since the 2,5-dithiol structure is excluded by ultraviolet spectral evidence, the 2-mercapto-5-thione structure (155) seems rather well established. It has previously been shown bj Thorn to predominate in chloroform solution, whereas he concluded that the dithione form (157) should predominate in ethanol solution. However, the pK i value for 155, — 1.36, makes it rather probable that Thorn used the monoanion of 155 instead of the acid itself for spectral comparison, and in that case his conclusions have a very weak foundation. 

Dimercapto-l,3,4-thiadiazole has been used as a reagent for photometric determination of metals under the name of Bismuthiol It has also, like several of its S-substituted derivatives, been used as a herbicide. ... 

An intricate system of T1- - -S and T1- - -N intermolecular bonds connects the molecular teutons of the dimethylthallium) III) bismuthiol complex (bismuthiol = 2,5-dimercapto-l,3,4-thiadiazole) into a complex supramolecular architecture, 51 [174]. 

A. Kaminaga, T. Tatsuma, T. Sotomura, N. Oyama, Reactivation and reduction of electrochemically inactivated polyaniline by 2,5-dimercapto-l,3,4-thiadiazole, Journal of the Electrochemical Society 1995, 142, L47. 

Kiya Y, Hutchison GR, Henderson JC et al (2006) Elucidation of the redox behavior of 2,5-dimercapto-l,3,4-thiadiazole (DMcT) at poly(3,4-ethylenedioxythiophene) (PEDOT)-modified electrodes and application of the DMcT-PEDOT composite cathodes to lithium/lithium ion batteries. Langmuir 22(25) 10554—10563... 

Gao J, Lowe MA, Conte S et al (2012) Poly(2,5-dimercapto-l,3,4-thiadiazole) as a cathode for rechargeable lithium batteries with dramatically improved performance. (Them Eur J 18 (27) 8521-8526... 

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