Sulfur monochloride, preparation

Niobium Pent chloride. Niobium pentachloride can be prepared in a variety of ways but most easily by direct chlorination of niobium metal. The reaction takes place at 300—350°C. Chlorination of a niobium pentoxide—carbon mixture also yields the pentachloride however, generally the latter is contaminated with niobium oxide trichloride. The pentachloride is a lemon-yeUow crystalline soHd that melts to a red-orange Hquid and hydrolyzes readily to hydrochloric acid and niobic acid. It is soluble in concentrated hydrochloric and sulfuric acids, sulfur monochloride, and many organic solvents. 

The principal commercial uses of sulfur monochloride are in the manufacture of lubricant additives and vulcanising agents for mbber (147,154,155) (see Lubrication AND lubricants Rubber chemicals). The preparation of additives for wear and load-bearing improvement of lubricating oils is generally carried out in two steps and the technology is described in numerous patents (155) (see Sulfurization and sulfchlorination). 

Manufacture. The manufacture of sulfur dichloride is similar to that of sulfur monochloride, except that the last stage of chlorination proceeds slowly and must be conducted at temperatures below 40°C. The preparation of a high assay sulfur dichloride requites special techniques, eg, continuous chlorination duriag distillation or distillation with traces of phosphoms trichloride or phosphoms pentasulfide [1314-80-3] (162—164). Cmde product containing 80 wt % sulfur dichloride to which is added 0.1 wt % phosphoms trichloride can be distilled to yield a 98—99 wt % pure sulfur dichloride, which can be stored for weeks at room temperature without appreciable change. 

Sinclair (92) has described an improved method for the preparation of methyl 6-chloro-6-deoxy- -D-glucopyranoside (137) from methyl a-D-glucopyranoside (11). The reaction was effected with sulfur monochloride S2C12 in N,N-dimethylformamide at room temperature and the... 

Thiadiazoles have proven of some utility as aromatic nuclei for medicinal agents. For example, the previous volume detailed the preparation of a series of "azolamide" diuretic agents based on this class of heterocycle. It is thus of note that the 1,2,5-thiadiazole ring provides the nucleus for a clinically useful agent for treatment of hypertension which operates by an entirely different mechanism, p-adrenergic blockade. In its preparation, reaction of the amide-nitrile 211 with sulfur monochloride leads directly to the substituted thiadiazole 212. ... 

Octachlorodibenzothiophene (88) has been formed by irradiation of a solution of pentachlorobenzenesulfenyl chloride in CCI4 in a low-pressure, cold cathode mercury arc (62%). A similar photolysis of bis-(pentachlorophenyl) sulfide, prepared by the action of sulfur monochloride and sulfuryl chloride on benzene in the presence of aluminum chloride, also yielded 88 (42%). Both routes are shown in Scheme 4. 

A series of five-membered heterocycles with two and three heteroatoms were synthesized. 4-Hydroxyisothiazoles 57 were prepared from a-amino ketones with sulfur monochloride (1968BCJ959). Polar solvents, especially N,Af-dimethylfor-mamide, were preferable (Scheme 28). In a similar reaction of 1-amino-l-phenyl-2-propanone with sulfur monochloride 5-chlorinated isothiazole 58 was obtained in high yield. 

Substituted 2-aminobenzothiazoles 61 can be prepared from N-arylthioureas with sulfur monochloride (1976DEP2601700). Yields are almost quantitative (Scheme 30). 

Resonance-stabilized bis-thiadiazinylpyridine 67 can be prepared from bifunctional amidine 68 and sulfur monochloride followed by treatment of... 

Chlorodithioles 96 can also be prepared from a reaction of N-alkyldi/sopro-pylamines, sulfur monochloride and DABCO followed by the addition of formic acid (2001MC165). 

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. 

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). 

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,... 

Bicyclic oxathiadiazapentalene 147 was prepared from acetonitrile derivative 148 with sulfur monochloride under the same conditions (1981USP4260624 Scheme 77). 

Chloro-3H-l,2,3-benzodithiazolium chloride 149 can be prepared from p-substituted Af-sulfinylanilines and sulfur monochloride when the substituent R is a good leaving group (1967RRC427 Scheme 78). 

The preparation of thianthrene 153 (R = H) from benzene, sulfur monochloride and aluminum chloride is the most inexpensive and simple method (1921LA265, 1956JA2163, 1976DEP2549435), also used for the preparation of other thianthrenes 153 (1972JCS(P1)1687 Scheme 81). 

Non-symmetric isomers of benzotrithiadiazepine 173 were prepared by 1 1 condensation of azathienes 171 with sulfur monochloride followed by intramolecular orf/zo-cyclization of intermediate 172 (2001CC1774). In the case of meta-substituted... 

Tetrathiane 195, similar in structure, was prepared by treatment of 3 2H)-benzofuranone with sulfur monochloride (1996T1961 Scheme 96). 

Even milder conditions were used for the preparation of thienopentathiepin 225 and pentathiepinofuran 226 from the corresponding heterocycles 224 (2006MC289). These heterocycles with sulfur monochloride and N-ethyldiisopro-pylamine at low (—10 °C) temperature gave pentathiepins 225 and 226 although in low yields (Scheme 119). 

Sulfur monochloride was successfully used for the preparation of pentathie-pino-fused poly(N-methylpyrrole) from the corresponding polymer (2005MI345). 

Hexathiaspirododecane 237 containing six sulfur atoms in the ring was prepared from titanocene complex 238 with sulfur monochloride (1996ZAAC1594). The structure of 237 had a chair conformation as identified by X-ray analysis (Scheme 126). 

N,N -Thiobiscarbamates also may be prepared by the reaction between a methylcarbamate ester and sulfur monochloride (21). 

Aminotriazoles which are appropriately substituted at the C(5)-position are important intermediates for the synthesis of 8-azapurines. These reactions have been reviewed <86AHC(39)ll7>. The pharmaceutically useful acyclonucleosides bearing 1,2,3-triazolines and 8-azapurines have been synthesized <888879). 4,5-Diaminotriazoles react with 1,2-dicarbonyl reagents to give 1,2,3-triazolo[4,5- )]pyrazines. 4,5-Diamino-2-phenyltriazole and sulfur monochloride afford the triazolo[4,5-c][l,2,5]thiadiazole (855) <86AHC(40)129>. The synthesis of triazolopyridines from triazoles has been described in a review <83AHC(34)79>. For further applications of substituted triazoles in preparations of complex heterocycles, see Section 4.01.4. 

The compound is generally made from arsenic trioxide by (i) passing chlorine over it or (ii) treating the trioxide with sulfur monochloride, S2CI2. Alternatively it is prepared from arsenic trioxide by distdlation with either concentrated hydrochloric acid or a mixture of sulfuric acid and a metal chloride. Arsenic trichloride may also be prepared by combination of arsenic and... 

Oakley and co-workers reported the transformation of l,2,5-thiadiazolo[3,4-/ ]pyrazines into tricyclic rings 55 and 57. Titanocene 55 was prepared by reaction of 5,6-dithiol derivative 54 with Cp2TiCl2 under basic conditions (Scheme 37) <1998JA352>, and 6-amino-5-thiol 56 was condensed with sulfur monochloride to give the 1,2,3-dithiazolidine derivative 57 in excellent yield (Scheme 38) <1999JA969>. 

Sinclair95 has described the preparation of methyl 6-chloro-6-deoxy-a-D-glucopyranoside from methyl a-D-glucopyranoside by treatment with sulfur monochloride (S2C12) in N,N-dimethylformam ide a yield of 30-35% was obtained on separation of the reaction products on a column of Darco G-60-Celite 535. 

An acyclic NCCN system in which the N-C links may be sp, sp2 or sp3 hybridized reacts with sulfur monochloride or sulfur dichloride to form the appropriate 1,2,5-thiadiazole (68AHC(9)107, 67JOC2823). Thus, diiminosuccinonitrile (384) gives 3,4-dicyano-l,2,5-thiadiazole (385) (72JOC4136). Tables 16 and 17 in CHEC 4.26 list the various substituted systems prepared in this fashion. 

Compounds which contain sulfur-nitrogen rings were known in the last century, but many new ones have been prepared in the last decade. It is currently an area of considerable interest. The ammonolysis of sulfur monochloride. S CIj, either in solution in an inert solvent or healed over solid ammonium chloride, yields letrasuffiir tetranitride ... 

The only report in the literature of the preparation of a tetrazine from a thiourea is that of Naik,270 who claimed to have isolated hexahydro-l,2,4,5-tetraphenyl-l,2,4,5-tetrazine-3,6-dithione (133) on treatment of l,3-diphenyl-2-thiourea with sulfur monochloride in refluxing benzene. Since the only evidence presented for structure 133... 

Tetrachlorothiophene has been prepared by the interaction of hexachlorobutadiene and sulfur at high temperatures. Sulfur monochloride is the other product, and both products are formed in essentially quantitative yield when three equivalents of sulfur are allowed to react with one equivalent of diene (59JOC1128). When l,4-diphenyl-2,3-dibenzylbutadiene (127) was heated with sulfur, an 85% yield of 2,5-diphenyl-3,4-dibenzylthiophene (128) was obtained. Under similar treatment, 6,7-dibenzylterphenyl (129) gave an 80% yield of the tetraphenylbenzo[c]thiophene (130) (78JHC1185). 

Halogen atoms have been placed at C-6 of substituted 6-deoxy-hexoses by a variety of interesting ways, and the products provide potential routes to 6-deoxyhexoses. Helferich and coworkers 4 reported a low yield of methyl 6-chloro-6-deoxy-a-D-glucoside which they prepared by reaction of the (suitably protected) corresponding 6-trityl ether with phosphorus pentachloride. Sinclair 44 has provided a convenient procedure for the preparation of the 6-chloro derivative in yields of 30-35% by allowing methyl a-D-glucopyranoside to react with sulfur monochloride, SjClj, in N,/V-dimethylformamide. A much better yield (73%) of the 6-bromo derivative was reported1 in the reaction of methyl 2,3,4-tri-O-benzoyl-6-O-trityl-a-D-altroside with phosphorus tribromide and bromine. 

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