Chlorination Using Sulfuryl Chloride

Many reagents are able to chlorinate aromatic pyrazole derivatives chlorine-water, chlorine in carbon tetrachloride, hypochlorous acid, chlorine in acetic acid (one of the best experimental procedures), hydrochloric acid and hydrogen peroxide in acetic acid, sulfuryl chloride (another useful procedure), etc. iV-Unsubstituted pyrazoles are often used as silver salts. When methyl groups are present they are sometimes chlorinated yielding CCI3 groups. Formation of dimers and trimers (308 R = C1) has also been observed. 

Sulfuryl chloride is used as a chlorinating and suhbnating agent in organic synthesis. It also is used in military gas. 

Fig. 1.33. An excess of sulfuryl chloride is used to chlorinate toluene to furnish benzal chloride (PhCHCy (while benzotrichloride = PhCC is obtained with an excess of chlorine).

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. 

By regulating the quantity of sulfuryl chloride, it is possible, in the chlorination of methane, to obtain a yield of 50 per cent chloroform. When a lesser quantity of sulfuryl chloride is used, it is obvious that a larger proportion of mono- and dichloromethanes is formed. The reaction is promoted by the presence of ionizing agents such as light, heat, metallic chlorides, and activated carbon. The heat of reaction is slightly greater... 

Definition Prod, of chlorosulfonation of a carbon tetrachloride solution of polyethylene with chlorine and sulfuryl chloride elastomer used in vulcanized and unvulcanized form vulcanizates have exc. oil/chemi ozone/weather resist. 

Sulfuryl chloride is used in organic chemistry as a chlorinating agent. At moderately high temperatures it decomposes as follows ... 

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,... 

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) ... 

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 ]. 

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. 

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 ... 

Sometimes lateral chlorination can occur on a methyl or alkylthio substituent, especially when phosphorus pentachloride or its mixtures with phosphoryl chloride are used (91JHC1549). Reactions of 2-methyl-4(I//)-quinoline (67) exemplify this behavior (81CPB1069) (Scheme 31) 2-chloro-3- and -4-methyquinolines are also subject to methyl chlorinations by similar reagents (91JHC1549). Sulfuryl chloride and NCS are also likely to induce a proportion of lateral chlorination (83KFZ1055 86S835). 

Iodine can, however, be displaced cleanly with bromine<150) and with chlorine if iodine monochloride or sulfuryl chloride and benzoyl peroxide are used as chlorinating agents.reactivity ratios for the displacement of bromine by chlorine from substituted bromo-benzenes have been found to be in the order p-phenyl > o-methoxy > p-chloro > un-... 

Kojic acid was brominated at position 6 with bromine water4 the 2-(chloromethyl) derivative of kojic acid was brominated with N-bromo-succinimide,87 and chlorinated with sulfuryl chloride and aluminum chloride,88 in both cases probably at C6. The C-benzoylation89 and C-acetylation90 of kojic acid, likewise at C6, was accomplished by Woods using a modification of the Friedel-Crafts reaction. The 2-carboxyethyl side chain was introduced at C6 in a reaction with 2-bromopropionic acid.91... 

Small amounts of amine salt are also generated as a side product.8-10 Other oxidative chlorinating approaches have been used with dialkyl phosphites as well, including methods using copper(II) chloride,11 sulfuryl chloride,12 and elemental chlorine.13 All of these provide the target dialkyl phosphorochloridate in high yield. 

Similarly, when the selective O-pivaloylation of trehalose was investigated by Richardson, Hough, and Cortes-Garcia, a number of useful derivatives were also obtained in quantities adequate to be of preparative value. Thus when 12 equivalents of pivaloyl chloride were employed for this esterification at — 20 °C, and the reactants were thereafter stored at room temperature for three days, a 61% yield of the 2,2 3,3, 4, 6,6 -heptapivalate was obtained, and following invertive chlorination with sulfuryl chloride, a displacement with different nucleophiles gave access to C-4-modified trehaloses, one example of which is shown in Scheme 17. 

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