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). 

A double end point, acid—base titration can be used to determine both sodium hydrosulfide and sodium sulfide content. Standardized hydrochloric acid is the titrant thymolphthalein and bromophenol blue are the indicators. Other bases having ionization constants in the ranges of the indicators used interfere with the analysis. Sodium thiosulfate and sodium thiocarbonate interfere quantitatively with the accuracy of the results. Detailed procedures to analyze sodium sulfide, sodium hydro sulfide, and sodium tetrasulfide are available (1). 

Carbonyl sulfide reacts slowly with aqueous alkah metal hydroxides, which can therefore be used to free carbonyl sulfide from acidic gases. The half-hfe at pH 12 (0.01 N KOH) is 3 min at 22°C. The product initially formed from carbonyl sulfide and aLkaU is the thiocarbonate [534-18-9] which then breaks down to carbonate and sulfide ... 

Thiophosgene reacts with alcohols and phenols to form chlorothionoformates or thiocarbonates. The most studied reactions of thiophosgene are with primary amines to give isothiocyanates and with secondary amines to give thiocarbamyl chlorides ... 

Vinylene sulfate — see 2,2-dioxide under 1,3,2-Dioxathiole Vinylene thiocarbonate synthesis, 6, 780 Vinylene trithiocarbonates photolysis, 7, 181 Violapterin... 

Alkyl S-Benzyl Thiocarbonate ROCOSCH2PI1 (Chart 2) Formation... 

When cysteine reacts with an alkyl or aiyl chloroformate, both the —SH and —NH groups are protected as a thiocarbonate and as a carbamate, respectively. Selective or simultaneous removal of the protective groups is possible. 

CH30C(0)SC1, 0-5°, 1.5 h r-BuSH, MeOH, 5 days, 97% crude, 46% pure. The reaction proceeds through an 5-sulfenyl thiocarbonate. 

A number of less-hazardous reagents that can be substituted for tert-hutyl azidoformate in tert-butoxycarbonylation reactions are available including 2-(te/t-butoxycarbonyloxyimino)-2-phenylacetonitrile (Aldrich Chemical Company), 0-teri-hutyl N-phenyl thiocarbonate (Eastman Organic Chemicals), di-butyl dicarbonate and tert-butyl phenyl carbonate. ... 

Under similar conditions, perfluoroalkyl iodides react with alkyl phosphates to give fluorinated phosphine oxides, phosphinates, and phosphines [54 (equation 49) The product formed depends upon the stoichiometry and type of iodide used. When sodium alkyl trithiocarbonates are used as substrates, perfluoroalkyl tri-thiocarbonates ate formed [55]. 

Dinitrophenyl)ethyl, 187 2-Cyano-1-phenylethyl, 188 S-Benzyl Thiocarbonate, 188 4-Ethoxy-1-naphthyl, 188 Methyl Dithiocarbonate, 189... 

Kohlen-schwarz, n. carbon black charcoal black, -schwefelwasserstoffsaure, /, (tri)-thiocarbonic acid (H2CS1). -spat, m. anthraconite whewellite, -spitze,/. carbon point, -staub, m. coal dust charcoal dust, -stick-stoff, m. cyanogen, -stickstoffsaure, /, car-bazotic acid (picric acid), -stoff, m. carbon,... 

Sulfkohlensaure, /. sulfocarbonic acid (tri-thiocarbonic acid) thionocarbonic acid (HOCSOH). 

Thio-germaniumsaure, /. thiogermanic acid, -harnstoff, m. thiourea, -kohlensaure, /. thiocarbonic acid, specif, trithiocarbonic acid. H CSa. 

A radical carboxyarylation approach was introduced as the key step in the total synthesis of several biologically important natural products (Scheme 27). Treatment of thiocarbonate derivatives 112 (R = Me or TBS) with 1.1 equiv of (TMS)3SiH in refluxing benzene and in the presence of AIBN (0.4 equiv added over 6h) as radical initiator, produced compound 113 in 44% yield. This remarkable transformation resulted from a radical cascade, involving (TMSlsSi radical addition to a thiocarbonyl function (112 114), 5-era cyclization (114->115) and intramolecular 1,5-ipso substitution (115 116) with the final ejection of (TMSlsSiS radical. 

Alcohols can readily be converted to carbonate and thiocarbonate derivatives. Under... 

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