Chlorination with sulfuryl chloride

Strong dehydrating agents such as phosphorous pentoxide or sulfur trioxide convert chlorosulfuric acid to its anhydride, pyrosulfuryl chloride [7791-27-7] S20 Cl2. Analogous trisulfuryl compounds have been identified in mixtures with sulfur trioxide (3,19). When boiled in the presence of mercury salts or other catalysts, chlorosulfuric acid decomposes quantitatively to sulfuryl chloride and sulfuric acid. The reverse reaction has been claimed as a preparative method (20), but it appears to proceed only under special conditions. Noncatalytic decomposition at temperatures at and above the boiling point also generates sulfuryl chloride, chlorine, sulfur dioxide, and other compounds. 

When l,2-dithiol-3-ones react with sulfuryl chloride, chlorine,242 or sulfenyl chlorides,243 the compounds shown in Scheme 18 are obtained. 

When 4,6-dihydro-1,2,5-triazepine (44) was treated with sulfuryl chloride, chlorine gas or NCS in an aprotic solvent, such as dichloromethane and carbon tetrachloride, the pyridazine (45) and/or the dichlorotriazepine (46) were isolated in high yields. A dramatic change has been observed when the chlorination was conducted in methanol. Neither pyridazine (45) nor triazepine (46) was... 

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). 

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. 

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,... 

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. 

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) ... 

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 ]. 

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). 

An 80% yield of benzyl chloride is obtained with sulfuryl chloride as chlorinating agent. Yields of >70% of benzyl chloride are obtained by the zinc chloride-catalyzed chloromethylation of benzene but formation of bis-chloromethyl ether presents a health hazard for this reaction pathway. 

Dichlorophenols. Among all the dichlorophenols, C H Cl O, it is 2,4-dichlorophenol that is produced in greatest quantity. 2,4-Dichlorophenol is used in manufacturing 2,4-dichlorophenoxyacetic acid [94-75-7] (2,4-D) and 2-(2,4-dichlorophenoxy)propionic acid [720-36-5] (2,4-DP). Industrially, 2,4-dichlorophenol can be obtained by chlorinating phenol, -chlorophenol, o-chlorophenol, or a mixture of these compounds in cast-iron reactors. The chlorinating agent may be chlorine or sulfuryl chloride in combination with a Lewis acid. For example ... 

The chlorosulfonation reaction is carried out with a mixture of sulfur dioxide and chlorine (37), sulfuryl chloride and chlorine (38), or sulfuryl chloride and a catalytic amount of an organic base (35,37). 

Reduction of indolenines with sodium and ethanol gives indolines. The pentachloropyr-role, obtained by chlorination of pyrrole with sulfuryl chloride at room temperature in anhydrous ether, was shown by spectroscopic methods to have an a-pyrrolenine (2H-pyrrole) structure (222). It is necessary, however, to postulate that it is in equilibrium with small but finite amounts of the isomeric /3-pyrrolenine form (3//-pyrrole 223), since pentachloropyrrole functions as a 2-aza- rather than as a 1-aza-butadiene in forming a cycloadduct (224) with styrene (80JOC435). Pentachloropyrrole acts as a dienophile in its reaction with cyclopentadiene via its ene moiety (81JOC3036). 

This activation of the ortho position is most strikingly illustrated in the reactivity of 2,5-dimethylthiophene, which competitive experiments have shown to undergo the SnCb-catalyzed Friedel-Crafts reaction more rapidly than thiophene and even 2-methylthiophene. The influence of the reagent on the isomer distribution is evident from the fact that 2-methoxythiophene is formylated and bromi-nated (with A -bromosuccinimide) only in the 5-position. Similarly, although 3-bromo-2-methylthiophene has been detected in the bromi-nation of 2-methylthiophene with bromine, only the 5-isomer (besides some side-chain bromination) is obtained in the bromination of alkylthiophenes with A -bromosuccinimide. ° However, the mechanism of the latter type of bromination is not established. No lines attributable to 2-methyl-3-thiocyanothiophene or 2-methyl-3-chIoro-thiophene could be detected in the NMR spectra of the substitution products (5-isomers) obtained upon thiocyanation with thiocyanogen or chlorination with sulfuryl chloride. 2-Methyl- and 2-ethyl-thiophene give, somewhat unexpectedly, upon alkylation with t-butyl chloride in the presence of Feds, only 5-t-butyl monosubstituted and... 

The substitution reactions of 3-acetamidothiophene have been extensively investigated. From the bromination with A-bromosuc-cinimide and from the chlorination with sulfuryl chloride or A-chloro-succinimide only the 2-isomers were obtained, the structure of which... 

In the first of these, the key step in the synthetic sequence involves an oxidative phenol coupling reaction patterned after the biosynthesis of the natural product. Preparation of the moiety that is to become the aromatic ring starts by methyla-tion of phloroglucinol (5) with methanolic hydrogen chloride to give the dimethyl ether (6). Treatment of that intermediate with sulfuryl chloride introduces the chlorine atom needed in the final product (7). 

A selective introduction of a chlorine atom at C-6 could be achieved (65) by treating 11 (and the / -anomer) with sulfuryl chloride in pyridine at — 70°C. followed by treatment of the resulting tetrachlorosulfate (83) with one mole of pyridine hydrochloride which gave 84. Heating of 84 with pyridine hydrochloride in chloroform resulted in further substitution by chloride to give 78 after dechlorosulfation. The above illustrated transformations support the proposed mechanism (65) for... 

Sulfuryl chloride, selective introduction of chlorine at C-6 with. . 181... 

Dichloromethyl methyl ether has been prepared by the chlorination of chlorodimethyl ether in the liquid5-4 or gas phase,5 by the reaction of chlorodimethyl ether with sulfuryl chloride and benzoyl peroxide,6 7 and by the treatment of methyl formate with phosphorus pentachloride.8-10... 

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