Potassium thiocarbonate

A number of substances, such as the most commonly used sulfur dioxide, can reduce selenous acid solution to an elemental selenium precipitate. This precipitation separates the selenium from most elements and serves as a basis for gravimetry. In a solution containing both selenous and teUurous acids, the selenium may be quantitatively separated from the latter by performing the reduction in a solution which is 8 to 9.5 W with respect to hydrochloric acid. When selenic acid may also be present, the addition of hydroxylamine hydrochloride is recommended along with the sulfur dioxide. A simple method for the separation and deterrnination of selenium(IV) and molybdenum(VI) in mixtures, based on selective precipitation with potassium thiocarbonate, has been developed (69). 

It has been shown 4 that when a solution of potassium thiocarbonate is boiled in an atmosphere of nitrogen, the following change takes place —... 

Tkiocarbonate. Potassium thiocarbonate, K2CS3, yellow solid, soluble, formed by reaction of potassium sulfide and CS2. 

Potassium thiocarbonate, K2CS3.—The interaction of potassium sulphide and carbon disulphide produces the thiocarbonate, a yellow substance very soluble in water.6... 

Potassium oxalate, 34, 83 Potassium permanganate, 30, 87 31,59 Potassium phthalimide, 38, 81 Potassium sulfide, 32,103 Potassium thiobenzoate, 32,101 Potassium thiocarbonate, 39, 78 Potassium thiocyanate, 32,39,40 Potassium trithiocarbonate, 39, 78 Prins reaction, 33, 72 Propane, 1, 3-dibromo-2,2-5m-(bromo-methyl)-, 31, 82... 

Under certain conditions thiocarbonates behave like simple sulphides thus, benzoyl chloride and a thiocarbonate in equimoleeular proportions yield benzoyl disulphide, which substance is also formed by the interaction of benzoyl chloride and potassium hydrogen sulphide followed by oxidation. The complex salts of the thiocarbonates are more stable than the simple salts. 

Spiroorthocarbonates were obtained by coupling of cyclic tin adduct 251, prepared from 1,2-dihydroxymethyl-benzene and dibutyltin oxide, with thiocarbonate 252. Reaction of the resulting orthocarbonate 253 with potassium A/z-butoxide in toluene afforded spiroorthocarbonate 254 (Scheme 77) <2003BKC1371>. 

Homochiral (2S,3S)-3-amino-2-phenylthietane (38) has been synthesized as a consequence of a series of reactions in which the thietane ring (37) is formed by the reaction of potassium O-ethyldi-thiocarbonate on the 1,3-ditosylate (36, R = OTs) or diiodide (36, R = 1) (94TA1327). 

Platinum Thiocarbonate is obtained in combination with 2 molecules of ammonia, PtCS3(NH3)2.H20, by crystallisation from a mixture of potassium chlor-platinite, concentrated ammonia and carbon disulphide.2 It yields red needles, insoluble in cold water, ammonium or sodium hydroxide. Exposed over sulphuric acid in vacuo it becomes anhydrous. 

Finally, a method for the preparation of (S-(alkyloxythiocarbonyl) derivatives has been introduced involving the reaction of ethyl potassium di-thiocarbonate with a glycosyl bromide. 

Sodium ferro-heptanitroso sulphide, NaFe4(NO)7S3.2H20, may be obtained in a similar manner to the potassium salt by boiling a solution of sodium ferro-dinitroso thiosulphate, as also by the action of sodium nitrite and sulphide solutions upon ferrous sulphate. In this latter reaction the sodium sulphide may be replaced by sodium thiocarbonate, Na2CS3. 

Coupling of a benzoic acid derivative under basic conditions is achieved with alkyl iodides," alkyl chlorides,dimethyl sulfate, or (l,1-dihydroperfluoroalkyl)phenyliodonium triflates. Common bases used arc potassium carbonate or sodium hydroxide (with phase-transfer catalyst). " Again, employing acid chlorides " - or anhydrides, " is the method of choice. The reaction can be performed without further activation, " " but in most cases the transformation takes place in the presence of the usual bases, triethylamine - " or pyridine " " " " " [in some cases 4-(dimethylamino)pyridine is added " ]. In a similar manner carbamates. thiocarbamates, " or thiocarbonates are synthesized. Perfluoropropcn-2-ol... 

From 1,6-hexanedithiol and MeOC(0)SCl the bis-sulfenyl thiocarbonate shown on the left side of equation (115) was obtained, which on treatment with potassium t-butoxide in methanol resulted in a macrocyclic bis-tiisulfane, (equation 115)d ... 

Deoxygenation of alcohols. Thiocarbonate derivatives of alcohols are con veniently reduced to alkanes by potassium and 18-crown-6 in /-butylamine. 

Five examples of bismuth tri(dithiocarbonate)s are known O-methyldithio-carbonate 1, 0-ethyldi-thiocarbonate 2, 0-isopropyldithiocarbonate 3, O-cyclohexyldithio-carbonate 4, and (9-benzyldithiocarbonate 5. All these compounds are prepared by a simple substitution reaction of BiCb with potassium dithiocarbonate [76AJC559, 85ICA(99)177, 92JCSR(22)231]. 

The episulfides (82), (83), (84), and (87) react readily with potassium methylxanthate in methanol at room temperature to give crystalline tri-thiocarbonate derivatives. Assuming attack at the primary position,the reaction from (84) may be formulated as follows. 

A particular case is the use of a hydrogen sulfide salt instead of the thiol, to effect the fragmentation. Treatment of the thiocarbonate derived from cysteine with 2 equiv of potassium hydrogensulfide in methanol results in the formation of the potassium salt of thiocysteine in 85% yield (eq 2). ... 

Preparation of Aromatic Thiols. Reaction of methoxycar-bonylsulfenyl chloride with benzene and substituted benzenes in the presence of Lewis acids (AICI3, BF3) in dichloromethane, carbon disulfide, or excess substrate as a solvent generates aryl thiocarbonates in low to good yields. Hydrolysis of the aryl thiocarbonates with aqueous methanolic potassium hydroxide generates the corresponding thiophenols in high yield (eq 9). ... 

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