Sulfur monochlorid salts

Ma.nufa.cture. Sulfur monochloride is made commercially by direct chlorination of sulfur, usually in a heel of sulfur chloride from a previous batch. The chlorination appears to proceed stepwise through higher sulfur chlorides (S Cl2, where x > 2). If conducted too quickly, the chlorination may yield products containing SCI2 and S Cl2 as well as S2CI2. A catalyst, eg, iron, iodine, or a trace of ferric chloride, faciUtates the reaction. The manufacture in the absence of Fe and Fe salts at 32—100°C has also been reported (149—151). 

A synthesis of benzofused 1,2,3-dithiazolium (Herz) salts by the action of sulfur monochloride on arylamines is the best-known synthesis of this class. Although it has been known for over 80 years (1922DEP360690), it is still in use. This chemistry was reviewed (1957CRV1011) and therefore here we describe the synthesis of heteroannulated 1,2,3-dithiazolium salts and new achievements in their preparation. 

Bis(l,2,3-dithiazoles) represent a new and potentially valuable class of heterocycles. A notable development is the "double Herz condensation" of 2,6-diaminonaphthalenes with sulfur monochloride which afforded naphtho-bis[l,2,3]dithiazole 110 after reduction of di-Herz salt 111 with triphenylantimony... 

Double Herz condensation of Af-alkylated 2,6-diaminopyridinium salts with sulfur monochloride is an effective procedure for the preparation of bis[l,2,3]dithiazolopyridinium salts 112 (2004CM1564) that were readily reduced to the corresponding dithiazolyl radicals 113 by decamethylferrocene (Scheme 56). 

Dithiazolium salts 129 were successfully isolated in the reaction of fluorinated enamines with sulfur monochloride yields were high (1993ZOR491 Scheme 64). 

An extensively studied and highly important 1,2,3-dithiazole - 4,5-dichloro-l,2, 3-dithiazol-l-ium chloride (Appel salt) 145 (R = Cl) - was first prepared by Appel and coworkers in 1985 by chlorination of chloroacetonitiile by sulfur monochloride in dichloromethane (1985CB1632) and it has been the most convenient procedure to date. Appel salt can be obtained also by prolonged chlorination of acetonitrile itself, or by the sulfur monochloride reaction with ethylamine the yields and experimental conditions were not disclosed (1985PS277). Recently, a series of mono-substituted acetonitriles were converted to 5-substituted-4-chloro-l,2,3-dithiazolium chlorides 145 (1999CC531,... 

Various mechanisms can be envisaged for the conversion of substituted acetonitriles into dithiazolium salt 145, yet no firm evidence has been given. The first step could be the chlorination of acetonitrile by sulfur monochloiide, as demonstrated for acetonitrile itself (1985CB1632) and for phenylacetonitrile (1939ZOK1329). This could be followed by sulfur monochloride addition to the cyano group, cyclization and ionization (Scheme 75). 

The compound 60 (C6S12) has been reported to be formed by reaction of the tetralithium salt 59 with sulfur monochloride at room temperature (Equation 4). In an alternative procedure, the tetrasodium salt was used. Similar procedures gave the CgSio and CgS analogues. Products were obtained as solvates and were not recrystallized <2005MCL575>. 

A synthesis of 2-thiolthieno[2,3-.. These dithiazolium salts (297) are obtained from the reaction of thienylcarboxylic acids with sulfur monochloride. Treatment of the dithiazolium hydroxide (297b) with carbon disulfide affords the thiol (298) (Scheme 55). 

The 5-methylpyrazolo[3,4- /]-l,2,3-dithiazol-2-ium chlorides (29), identified as the products of reaction between the l-methyl-3-aminopyrazoles (92) and sulfur monochloride, were highly colored, moisture-sensitive salts which were obtained in good yield (Equation (15)). The slightly lower yields of derivatives (29c,d) may reflect a reduced electrophilicity due to the carboalkoxy substituent in the 6-position <84JOCl224>. 

The first 1,2,3-thiadiazole synthesized, 1,2,3-benzothiadiazole, was prepared by diazotiz-ation of o-aminothiophenol with nitrous acid (equation 31) (B-61MI42400), and recently sodium nitrite-acetic acid has been substituted for nitrous acid (B-79MI42400),. Another modification, thermal decomposition of diazonium acetate (34), affords benzothiadiazole in good yield in contrast to the variable yields usually experienced in the diazotization of o-aminothiophenols (equation 32) (78SST(5)43l). Benzothiadiazoles are also available directly from aromatic amines (equation 33) (70JCS(C)2250). Sulfur monochloride reacts with the amine to form a benzothiazothiolium salt which reacts with nitrous acid to yield a chlorinated 1,2,3-benzothiadiazole (35). This process, depending on the aromatic ring substitution, may afford a number of products, and yields are variable. 

Benzoyl disulfide has been obtained by the reaction of benzoyl chloride with hydrogen sulfide, hydrogen disulfide, hydrogen trisulfide, potassium sulfide, sodium disulfide, lead sulfide, sodium hydrosulfite, sodium thiosulfate, sulfhydrylmagnesium bromide, and thiobenzamide. It is also formed by reaction of benzoic anhydride with hydrogen sulfide. The better preparative methods involve the oxidation of thiobenzoic add by means of air,hydrogen peroxide or sulfur monochloride, or of the sodium or potassium salt by means of air, - chlorine, iodine, copper sulfate, - potassium ferricyanide, - or ferric chloride. - ... 

Reaction of aromatic amines with sulfur monochloride and an acyl chloride in the presence of Zn salts to give 1,3-benzothiazoles (see 1st edition). 

An interesting topological effect is the increased terminal chlorination of fatty acids when they are adsorbed and aligned on alumina Silicon disulfide and particularly boron sulfide have been used with advantage instead of phosphorus pentasulfide to replace carbonyl oxygen by sulfur The addition of sulfur monochloride to olefins followed by reduction of the adduct with sodium sulfide provides a convenient inexpensive route to a large number of episulfides A direct conversion of ar. nitro compounds to isothiocyanates has been reported Sec. phosphines add easily to olefins under UV-irradiation Advances in peptide synthesis include the use of acyloxyphospho-nium salts prepared with hexamethylphosphoramide a simple synthesis with triphenyl phosphite , and the use 4-picolyl esters at the... 

The authors of this work were able to carry out iodination only when they used iodine monochloride. Compound 233 is unstable when stored in air and loses iodine quite rapidly. We were unable to isolate reaction products in the case of sulfonation with sulpfuric acid. The most convenient sulfonating reagent was a solution of sulfur trioxide in dichlorethane. The sulfonic derivative 234 was very hygroscopic and was further converted into the disodium or bis(isobutylammonium) salt. 

A solution of 5.0 g of a-ethyl-p-(aminophenyl)propionic acid in 100 ml of water containing 5 ml of concentrated hydrochloric acid was added over a period of Vi hour to a stirred solution of 3.2 ml of iodine monochloride in 25 ml of water and 25 ml of concentrated hydrochloric acid heated to 60°C. After addition was complete, the heating was continued for Vi hour longer at 60° to 70°C. A black oil separated which gradually solidified. The mixture was then cooled and sodium bisulfite was added to decolorize. Recrystallization of the product from methanol gave about 8 g of a-ethyl-p-(2,4,6-triiodo-3-aminophenyl)-propionic acid, MP 147° to 150°C. The product could be further purified by precipitation of its morpholine salt from ether solution and regeneration of the free amino acid by treatment of a methanol solution of the morpholine salt with sulfur dioxide. The pure amino acid had the MP 155° to 156.5°C (corr). 

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