3 -thio-, preparation

Ullman reaction The synthesis of diaryls by the condensation of aromatic halides with themselves or other aromatic halides, with the concomitant removal of halogens by a metal, e.g. copper powder thus bromobenzene gives diphenyl. The reaction may be extended to the preparation of diaryl ethers and diaryl thio-ethers by coupling a metal phenolate with an aryl halide. 

Mercaptans (or thio-alcohols or thiols), the sulphur analogues of the alcohols, were formerly prepared by the interaction of an alkyl halide and sodium hydrosulphide in alcoholic solution ... 

Thio-p-cresol (p-tolyl mercaptan), p-CHjCjH SH. This compound may be similarly prepared from p-toluenesulphonyl chloride (Section IV,207). The thio-p-cresol crystallises in the steam distillate and is collected and dried m.p. 43°. The b.p. under normal pressure is 194r-195°. 

Wijs solution (for iodine number) dissolve 13 g resublimed iodine in 1 liter of glacial acetic acid (99.5%), and pass in washed and dried (over or through H2SO4) chlorine gas until the original thio titration of the solution is not quite doubled. There should be only a slight excess of iodine and no excess of chlorine. Preserve the solution in amber colored bottles sealed with paraffin. Do not use the solution after it has been prepared for more than 30 days. 

The perfluoroalkane sulfonic acids were fkst reported ki 1954. Trifluoromethanesulfonic acid was obtained by the oxidation of bis(ttifluoromethyl thio) mercury with aqueous hydrogen peroxide (1). The preparation of a series of perfluoroalkanesulfonic acids derived from electrochemical fluotination (ECF) of alkane sulfonyl haUdes was also disclosed ki the same year (2). The synthetic operations employed when the perfluoroalkanesulfonic acid is derived from electrochemical fluotination, which is the best method of preparation, are shown ki equations 1—3. 

Famotidine. Also known as Pepcid, famotidine [76824-35-6] (AT-(aminosulfonyl)-3-([[2-[(diaminomethylene) amino]-4-thia2olyl] methyl]thio)propariimidamide (2) is a white to pale yellow crystalline compound, freely soluble in glacial acetic acid, slightly soluble in methanol, very slightly soluble in water, and practically insoluble in ethanol. It may be prepared by the method described in Reference 3. 

The Mpt and Ppt derivatives can be prepared from an amino acid and the thio-phosphinyl chloride (Me2PSCl or Ph2PSCl, respectively, 41-78% yield, lysine gives 16% yield)." The Mpt group is cleaved with HCl or Ph P- HCl and is cleaved 60 times faster than the BOC group. The Ppt group is the more stable of the two groups. 

The only practical method for preparing alkylene thioureas is by the action of the diamines upon carbon disulfide in aqueous alcohol. The final heating is essential to convert the thio-carbamic acid into the cyclic compound, the addition of hydrochloric acid being beneficial. ... 

Aryl isothiocyanates can be prepared by the action of thio-phosgene on the arylamine (this reaction fails with naphthyl compounds), by fission of a 5ym-diaryIthiourea with acidic reagents (this reaction involves the loss of half the amine used), and by the decomposition of an ammonium aryldithiocar-bamate (low yields are reported for naphthyl and other compounds).The procedure described here is that of Baxter, Cymerman-Craig, Moyle, and White. ... 

Triazole-3(5)-thiol has been prepared by heating thio-semicarbazide and formic acid, by heating l-formyl-3-thiosemi-carbazide, and by heating 1,3,5-triazine and thiosemicarbazide. The ring closure of l-formyl-3-thiosemicarbazide using aqueous base was suggested by L. F. Audrieth and F. Hersman. 

Me3SiCH2CH=CH2, TsOH, CH3CN, 70-80°, 1-2 h, 90-95% yield. " This silylating reagent is stable to moisture. Allylsilanes can be used to protect alcohols, phenols, and carboxylic acids there is no reaction with thio-phenol, except when Cp3S03H is used as a catalyst. The method is also applicable to the formation of r-butyldimethylsilyl derivatives the silyl ether of cyclohexanol was prepared in 95% yield from allyl-r-butyl-dimethylsilane. Iodine, bromine, trimethylsilyl bromide, and trimethylsilyl iodide have also been used as catalysts. Nafion-H has been shown to be an effective catalyst. ... 

By contrast to the plethora of simple oxo-halides and thiohalides of P, the corresponding derivatives of P are fugitive species that require matrix isolation techniques for preparation and characterization ClPO, BrPO, FPS and BrPS all form non-linear triatomic molecules, as expected. The corresponding oxosulfide, BrP(0)S, and its thio-analogue, FP(S)S, have also recently been isolated. 

These workers also prepared the thio analog of 17 (R = H) by treating 16 (R = H) with aqueous ammonia to provide the P-oxoamide, which was converted into the corresponding enolized P-thioxoamide 18 by treatment with hydrogen sulfide and hydrogen chloride in ethanol. Compound 19 was synthesized by oxidation of 18 with iodine in ethanol under basic conditions. 

Campaigne et al. have used 3-thenyl bromide obtained by benzoyl peroxide-catalyzed, side-chain bromination of 3-methylthiophene with A -bromosuccinimide, as a starting material for 3-substituted thiophenes. - 22 3-Methylthiophene is now prepared commercially from itaconic acid. The reactive halogen in 3-thenyl bromide could be directly reacted with a variety of nucleophiles, such as cyanide, or malonate, to give more complex 3-substituted compounds. 3-Thenyl bromide was converted by the Sommelet reaction to 3-thio-phenealdehyde which, with silver oxide, was oxidized to 3-thio-... 

In the absence of oxygen, these thiolene-2-ones are rather stable and have been kept at 0°C for several months. 3-Hydroxythiophene, on the other hand, which has been prepared in low yield from 3-thio-phenemagnesium bromide in the same way as the 2-isomer, or through decarboxylation of 3-hydroxy-2-thiophenecarboxylic acid, "" is very unstable. Its IR spectrum indicates that it also exists as a tautomeric mixture largely in its enolic form. ... 

The thiophene analog of chloramphenicol (255) has been synthesized,as also have been similar structures. The antibacterial activity of all was much lower than that of the natural antibiotic. The thioamide of 2-thenoic acid has been prepared in a study of potential antitubercular compounds. It did not surpass thioisonico-tinamide in antitubercular activity. The thiosemicarbazones of thio-phenealdehydes and ketones (cf. Section VII,D) show high activity against Mycobacterium tuberculosis, but are very toxic. The thiosemi-carbazone of 4-(2-thienyl)-3-buten-2-one has been reported to be capable of completely inhibiting the in vitro growth of M. tuberculosis even in relatively low concentrations. ... 

Thioxo-3-oxo-2,3,4,5-tetrahydro-l,2,4-triazine (4-thio-6-azauracil) (88) and 3,5-dithioxo-2,3,4,5-tetrahydro-l,2,4-triazine (2,4-dithio-6-azauracil) (89) w ere prepared by Hitchings et al. treating 6-aza-... 

Alkylation in position 3 has a still more pronounced effect. The thiosemi carbazones (101) obtained here were prepared either from 3-methylisothiosemicarbazide hydroiodide or by methylation of thio-semicarbazones. Their cyclization was performed either by boiling in alcohol or by heating to the melting point (102). The presence of... 

The thio analogs of the substances just mentioned, the alkylmer-capto derivatives, are more stable and readily available (e.g., Section II,B,4,b). These derivatives were used for the preparation of the 3-hydrazino and 3,5-dihydrazino derivatives. ... 

Sorm et a/. prepared azacytidine and some of its derivatives in a similar way. The 4-thio derivative was obtained from 2, 3, 5 -tri-0-acetyl- or 2, 3, 5 -tri-0-benzoyl-6-azauridine by treatment with phosphorus pentasulfide this liberated 4-thio-6-azauridine (126) which was identified with 4-thio-6-azauracil on comparing the UV spectra. Treatment with ammonia produced 6-azacytidine (127) treatment with hydrazine, hydroxylamine, and n-butylamine yielded the corresponding derivatives. 

Preparation of 6-azacytidine-5 -phosphate by direct phosphorylation with cyanoethylphosphate was not successful. The substance could be prepared, however, on ammonia treatment of 4-thio-6-azauridine-5 -phosphate which was obtained by phosphorylation of 2, 3 -isopropyl-iden-4 thio-6-azauridine with pyrophosphoryl chloride. From mor-pholidate of 6-azacytidine-5 -phosphate, 6-azacytidine-5 -diphosphate was prepared by the action of phosphoric acid. ... 

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