Sulfuryl chloride

Sulfuryl chloride was first prepared by Regnault1 in 1838 by the action of chlorine on a mixture of ethylene and sulfur dioxide. The compound can also be produced by causing 

Danneel2 used granulated, activated charcoal as a catalyst. The method of Danneel can be readily modified to permit the production of relatively large amounts of this very important reagent. 

The apparatus of Danneel is modified as shown in Fig. 21 to include a gauge for regulating the flow of the two gases. 

An ordinary, straight glass condenser is used as the reaction chamber. The advantages of this chamber are that the charcoal may be activated in the pyrex glass tube of the 

The yield from an actual run, using 5.34 kg. of sulfur dioxide and 5.68 kg. of chlorine, was 10.45 kg. This is a yield of 96.2 per cent based on the chlorine used or 97.5 per cent based on the sulfur dioxide used. 

Reactivity at 0-3, in addition to that at 0-4 and 0-6, was observed with methyl )3-D-galactopyranoside, which, when treated with sulfuryl chloride, yielded methyl 3,4,6-trichloro-3,4,6-trideoxy-/J-D-allopyranoside 2-(chlorosulfate) in 56% yield.352 In contrast, under similar conditions, methyl a-D-galactopyranoside gave352 methyl 4,6-dichloro-4,6-dideoxy-a-D-glucopyranoside 2,3-di(chlorosulfate). Further examples of the dependence of the reactivity on the configuration of C-l are the conversion of methyl 4,6-0-benzylidene-/3-D-glucopyranoside into methyl 4,6-0-benzylidene-3-chloro-3-deoxy-/3-i allopyranoside by sulfuryl chloride,352 and of methyl 4,6-0-benzylidene-a-D-glucopyranoside, under similar conditions, into the 2,3-di(chlorosulfate).355 

Throughout the series of glycosides studied, a common feature is the inertness of HO-2 towards replacement. The reason for this most probably lies in the inductive elfect at C-2, caused by the two /3-oxygen atoms attached to C-l. 

Many other glycosides have been subjected to selective chlorination with sulfuryl chloride. Methyl /3-L-arabinopyranoside afforded methyl 4-chloro-4-deoxy-a-D-xylopyranoside 2,3-di(chlorosulfate) in 29% yield, whereas the a-L anomer gave357 methyl 3,4-dichloro-3,4-dideoxy-/3-i)-ribopyranoside 2-(chlorosulfate) (30%). Methyl /3-d-ribopyranoside was converted into methyl 3,4-dichloro-3,4-dideoxy-a-L-arabinopyranoside through the action of pyridine hydrochloride on its 2,3,4-tri(chlorosulfate).358 Methyl a-D-lyxopyranoside gave only the 2,3,4-tri(chlorosulfate),353 as would be expected from the disposition of its hydroxyl groups, similar to that in the rhamno- and manno-pyranosides. Methyl a-D-altropyranoside was transformed into the 6-chloro-6-deoxy 2,3,4-tri(chlorosulfate) derivative in 80% yield.353 

An important step in the synthesis of paratose (3,6-dideoxy-n-rtfoo-hexose) involved the conversion of methyl 3-chloro-3-deoxy-/8-D-allopyranoside into methyl 3,6-dichloro-3,6-dideoxy-/8-D-allo-pyranoside in 33% yield.359 

D-Lyxose yielded a D-lyxosyl chloride 2,3,4-tri(chlorosulfate) which, on treatment with chloride ion, led to a dichlorodideoxy compound, most probably 2,4-dichloro-2,4-dideoxy-L-arabinose.353 D-Glucose gave a compound presumed to be 4,6-dichloro-4,6-dideoxy-a,/3-D-galactosyl chloride 2,3-di(chlorosulfate),360 and D-xylose afforded a monochloromonodeoxy derivative formulated, on indirect evidence, as 4-chloro-4-deoxy-L-arabinopyranosyl chloride 2,3-di(chlorosulfate).360 3,4-Dichloro-3,4-dideoxy-/3-D-ribopyranosyl chloride 2-(chlorosulfate) was the major, and 4-chloro-4-deoxy-a-D-xylopyranosyl chloride 2,3-di(chlorosulfate) the minor, product from the reaction of L-arabinose with sulfuryl chloride at room temperature for 24 hours.357,361 It has been established that, on reaction with sulfuryl chloride at low temperature, crystalline a-D-xylopyranose and /3-D-lyxopyranose afford, respectively, the 2,4,6-tri(chlorosul-fate)s of /3-D-xylopyranosyl chloride and a-D-lyxopyranosyl chloride,362 363 confirming that substitution at C-l occurs by an Sn2 process on a l-(chlorosulfuric) ester intermediate. 

All the processes operate in the gas phase in continuously operated plants with an activated charcoal catalyst. Unreacted sulfur dioxide, or sulfur dioxide produced as a byproduct, is converted in the gas phase with chlorine to sulfuryl chloride. This is fed back into the thionyl chloride synthesis and there reacts with sulfur dichloride or disulfur dichloride and chlorine to thionyl chloride. Unreacted sulfur dichloride is reacted with sulfur in the presence of a catalyst to disulfur dichloride. Pure thionyl chloride is obtained by fractional distillation. 

Applications 45 10 t of thionyl chloride was consumed worldwide in 1992. It is utilized as a chlorination agent e.g. for the manufacture of organic intermediates, pesticides, insecticides, pharmaceuticals, dyes and pigments. It is also utilized for the dehydration of metal chloride hydrates, the chlorination of metal oxides, as a non-aqueous electrolyte and as a cathodic material in particular types of lithium batteries. 

The byproducts sulfur dioxide and hydrogen chloride, formed upon substitution of the hydroxy-groups of alcohols and carboxylic acids, can be largely absorbed by alkaline scrubbing. The thereby formed sulfite can be oxidized by chlorine to sulfate in alkaline solution. 

Manufacture Industrially sulfuryl chloride is almost exclusively produced by reacting sulfur dioxide with chlorine on an activated charcoal catalyst in a well-cooled tubular converter. Reaction of disulfur dichloride with 

Application Sulfuryl chloride is used as a chlorination and sulfochlorination agent in the organic chemical industry, in particular for selective chlorination (e.g. for the side chains of aromatic compounds) and in the manufacture of organic intermediates for dyes, pharmaceuticals, pesticides and disinfectants. 

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The only acid-resistant protective group for carbonyl functions is the dicyanomethy-lene group formed by Knoevenagel condensation with malononitrile. Friedel-Crafts acylation conditions, treatment with hot mineral acids, and chlorination with sulfuryl chloride do not affect this group. They have, however, to be cleaved by rather drastic treatment with concentrated alkaline solutions (J.B. Basttis, 1963 H. Fischer, 1932 R.B. Woodward, 1960, 1961). 

Acetamido-4-methyl-5-thiazolyl-sulfuryl chloride gives by hydrolysis the acid, which on heating with H2SO4 is reported to give the 2-sulfamic acid (337). 

This simplified method gives 2-aminothiazole in good yield (50 to 70%) (311, 330), Other reactants can replace iodine, for example, chlorine, bromine, sulfuryl chloride, chlorosulfonic acid, or sulfur monochloride also give good results. 

Chloroacetyl chloride is manufactured by reaction of chloroacetic acid with chlorinating agents such as phosphoms oxychloride, phosphoms trichloride, sulfuryl chloride, or phosgene (42—44). Various catalysts have been used to promote the reaction. Chloroacetyl chloride is also produced by chlorination of acetyl chloride (45—47), the oxidation of 1,1-dichloroethene (48,49), and the addition of chlorine to ketene (50,51). Dichloroacetyl and trichloroacetyl chloride are produced by oxidation of trichloroethylene or tetrachloroethylene, respectively. 

Reaction with Sulfur Electrophiles. Bisa2iridine compounds can be prepared from sulfur dichloride, thionyl chloride, or sulfuryl chloride... 

Ha.logena.tlon, 3-Chloroindole can be obtained by chlorination with either hypochlorite ion or with sulfuryl chloride. In the former case the reaction proceeds through a 1-chloroindole intermediate (13). 3-Chloroindole [16863-96-0] is quite unstable to acidic aqueous solution, in which it is hydroly2ed to oxindole. 3-Bromoindole [1484-27-1] has been obtained from indole using pytidinium tribromide as the source of electrophilic bromine. Indole reacts with iodine to give 3-iodoindole [26340-47-6]. Both the 3-bromo and 3-iodo compounds are susceptible to hydrolysis in acid but are relatively stable in base. 

A more energy-efficient variation of photohalogenation, which has been used since the 1940s to produce chlorinated solvents, is the Kharasch process (45). Ultraviolet radiation is used to photocleave ben2oyl peroxide (see Peroxides and peroxide compounds). The radical products react with sulfuryl chloride (from SO2 and CI2) to Hberate atomic chlorine and initiate a radical chain process in which hydrocarbons become halogenated. Thus, for Ar = aryl,... 

Oxidation. The synthesis of quinolinic acid and its subsequent decarboxylation to nicotinic acid [59-67-6] (7) has been accompHshed direcdy in 79% yield using a nitric—sulfuric acid mixture above 220°C (25). A wide variety of oxidants have been used in the preparation of quinoline N-oxide. This substrate has proved to be useful in the preparation of 2-chloroquinoline [612-62-4] and 4-chloroquinoline [611 -35-8] using sulfuryl chloride (26). The oxidized nitrogen is readily reduced with DMSO (27) (see Amine oxides). 

Direct halogenation of sucrose has also been achieved using a combination of DMF—methanesulfonyl chloride (88), sulfuryl chloride—pyridine (89), carbon tetrachloride—triphenylphosphine—pyridine (90), and thionyl chloride—pyridine—1,1,2-trichloroethane (91). Treatment of sucrose with carbon tetrachloride—triphenylphosphine—pyridine at 70°C for 2 h gave 6,6 -dichloro-6,6 -dideoxysucrose in 92% yield. The greater reactivity of the 6 and 6 primary hydroxyl groups has been associated with a bulky halogenating complex formed from triphenylphosphine dihaUde ((CgH )2P=CX2) and pyridine (90). 

The first displacement reaction at C-2 position in carbohydrates was achieved during the study of sulfuryl chloride reaction with sucrose (92). Treatment of 3,4,6,3, 4, 6 -hexa-0-acetylsucrose 2,l -bis(chlorosulfate) with lithium chloride in hexamethylphosphoric triamide at 80°C for 20 h led to the corresponding 2,l -maimo derivative in 73% yield. 

At present, thionyl chloride is produced commercially by the continuous reaction of sulfur dioxide (or sulfur trioxide) with sulfur monochloride (or sulfur dichloride) mixed with excess chlorine. The reaction is conducted in the gaseous phase at elevated temperature over activated carbon (178). Unreacted sulfur dioxide is mixed with the stoichiometric amount of chlorine and allowed to react at low temperature over activated carbon to form sulfuryl chloride, which is fed back to the main thionyl chloride reactor. 

A number of processes have been devised for purifying thionyl chloride. A recommended laboratory method involves distillation from quinoline and boiled linseed oil. Commercial processes involve adding various high boiling olefins such as styrene (qv) to react with the sulfur chlorides to form adducts that remain in the distillation residue when the thionyl chloride is redistilled (179). Alternatively, sulfur can be fed into the top of the distillation column to react with the sulfur dichloride (180). Commercial thionyl chloride has a purity of 98—99.6% minimum, having sulfur dioxide, sulfur chlorides, and sulfuryl chloride as possible impurities. These can be determined by gas chromatography (181). 

Physical Properties. Sulfuryl chloride [7791-25-5] SO2CI2, is a colorless to light yellow Hquid with a pungent odor. Physical and thermodynamic properties are Hsted ia Table 7. Sulfuryl chloride dissolves sulfur dioxide, bromine, iodine, and ferric chloride. Various quaternary alkyl ammonium salts dissolve ia sulfuryl chloride to produce highly conductive solutions. Sulfuryl chloride is miscible with acetic acid and ether but not with hexane (193,194). 

Table 7. Physical and Thermodynamic Properties of Sulfuryl Chloride...

Chemical Properties. The chemistry of sulfuryl chloride has been reviewed (170,172,195). It is stable at room temperature but readily dissociates to sulfur dioxide and chlorine when heated. The equiUbrium constant has the following values (194) ... 

The decomposition of sulfuryl chloride is accelerated by light and catalyzed by aluminum chloride and charcoal. Many of the reactions of sulfuryl chloride are explainable on the basis of its dissociation products. Sulfuryl chloride reacts with sulfur at 200°C or at ambient temperature in the presence of aluminum chloride producing sulfur monochloride. It hberates bromine or iodine from bromides or iodides. Sulfuryl chloride does not mix readily with water and hydrolyzes rather slowly. 

The reaction of sulfuryl chloride with a stoichiometric amount of sulfuric acid produces chlorosulfuric acid [7790-94-5] (chlorosulfonic acid) ... 

This latter reaction is reversible. Sulfuryl chloride can be fractionally distilled from boiling chlorosulfonic acid ia the presence of a catalyst, eg, a mercuric salt. 

Iodine reacts with sulfuryl chloride ia the presence of aluminum chloride as catalyst-forming iodine chlorides. Sulfuryl chloride reacts with anhydrous ammonia yielding a series of sulfamides of the general formula NH2S02(NHS02) NH2, where n > 0. A cycHc compound of the formula... 

The organic chemistry of sulfuryl chloride involves its use in chlorination and sulfonation (172,175,196,197). As a chlorinating agent, sulfuryl chloride is often mote selective than elemental chlorine. The use of sulfuryl chloride as a chlorinating agent often allows mote convenient handling and measurement as well as better temperature control because of the lower heat of reaction as compared with chlorine. Sulfuryl chloride sometimes affords better selectivity than chlorine in chlorination of active methylene compounds (198—200) ... 

With alkylamines, sulfuryl chloride can produce alkylsulfamoyl chlorides, which are useful intermediates in herbicide syntheses (175). 

Ma.nufa.cture. The preparation of sulfuryl chloride is carried out by feeding dry sulfur dioxide and chlorine into a water-cooled glass-lined steel vessel containing a catalyst, eg, activated charcoal. Alternatively, chlorine is passed into Hquefted sulfur dioxide at ca 0°C in the presence of a dissolved catalyst, eg, camphor, a terpene hydrocarbon, an ether, or an ester. The sulfuryl chloride is purified by distillation the commercial product is typically 99 wt % pure, as measured by ASTM distillation method D850. 

Economic Aspects. The tmddoad price of sulfuryl chloride in mid-1995 was l/kg. Occidental Chemical Company (Niagara Falls, New York) is the only merchant producer. A large amount is made and used captively by DuPont for manufacture of chlorosulfonated elastomer. 

Health and Safety Factors. Sulfuryl chloride is both corrosive to the skin and toxic upon inhalation. The TLV suggested by the manufacturer is 1 ppm. The vapors irritate the eyes and upper respiratory tract, causing prompt symptoms ranging from coughing to extreme bronchial irritation and pulmonary edema. The DOT label is Corrosive, Poison. 

Uses. Uses of sulfuryl chloride include the manufacture of chlorophenols, eg, chlorothymol for use as disinfectants. It is also used in the manufacture of alpha-chlorinated acetoacetic derivatives, eg, CH2COCHCICOOC2H3, which ate precursors for important substituted imidazole dmgs,... 

Oxidation of sulfur dioxide in aqueous solution, as in clouds, can be catalyzed synergistically by iron and manganese (225). Ammonia can be used to scmb sulfur dioxide from gas streams in the presence of air. The product is largely ammonium sulfate formed by oxidation in the absence of any catalyst (226). The oxidation of SO2 catalyzed by nitrogen oxides was important in the eady processes for manufacture of sulfuric acid (qv). Sulfur dioxide reacts with chlorine or bromine forming sulfuryl chloride or bromide [507-16 ]. 

Isomer mixtures are generally obtained. Chlorosulfonation is used to produce chlorosulfonated polyethylene, a curable thermoplastic. Preformed sulfuryl chloride may also be used. 

E. J. Diaan and J. E. Bieron,M Survey ofPeactions of Ehionyl Chloride, Sulfuryl Chloride and Sulfur Chlorides, Occidental Chemical Corp., Niagara EaUs, N.Y., 1990. 

Sulfuryl Chloride, data buUetia, Occidental Chemical Corp., Basic Chemicals Group, Dallas, Tex., 1994. 

Titanium(IV) sulfate can be prepared by the reaction of titanium tetrachloride with sulfur trioxide dissolved in sulfuryl chloride. 

The alkylation can also be accompHshed using tetraalkyltin compounds. Alkyldiiodostibines are formed in about 20% yield via the interaction of alkylmagnesium iodides and antimony trichloride (67). Dialkylchlorostibines are obtained in good yields by the cleavage of tetraalkyldistibines using sulfuryl chloride (91) ... 

Continuous chlorination of benzene at 30—50°C in the presence of a Lewis acid typically yields 85% monochlorobenzene. Temperatures in the range of 150—190°C favor production of the dichlorobenzene products. The para isomer is produced in a ratio of 2—3 to 1 of the ortho isomer. Other methods of aromatic ring chlorination include use of a mixture of hydrogen chloride and air in the presence of a copper—salt catalyst, or sulfuryl chloride in the presence of aluminum chloride at ambient temperatures. Free-radical chlorination of toluene successively yields benzyl chloride, benzal chloride, and benzotrichloride. Related chlorination agents include sulfuryl chloride, tert-huty hypochlorite, and /V-ch1orosuccinimide which yield benzyl chloride under the influence of light, heat, or radical initiators. 

Dichlorotoluene (2,4-dichloro-l-methylben2ene) constitutes 80—85% of the dichlorotoluene fraction obtained in the chlorination of PCT with antimony trichloride (76) or zirconium tetrachloride (77) catalysts. It is separated from 3,4-dichlorotoluene (l,2-dichloro-4-methylben2ene), the principal contaminant, by distillation. Chlorination of OCT with sulfuryl chloride gives mainly 2,4-dichlorotoluene and small amounts of the 2,3 isomer (78). 

Benzotrichloride with zinc chloride as catalyst reacts with ethylene glycol to form 2-chloroethyl benzoate [7335-25-3] (35). Perchlorotoluene is formed by chlorination with a solution of sulfur monochloride and aluminum chloride in sulfuryl chloride (36). 

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