Sulfur dichloride, reaction with aromatic

Sulfinic esters, aromatic, by oxidation of disulfides in alcohols, 46, 64 Sulfonation of D,L-camphor to d,l-10-camphorsulfonic acid, 46,12 Sulfoxides, table of examples of preparation from sulfides with sodium metaperiodate, 46,79 Sulfur dioxide, reaction with styrene phosphorus pentachloride to give styrylphosphonic dichloride, 46,... 

N-Arylamidines act as 1,5-dinucleophiles towards sulfur dichloride, N-sulfinyltosylamide and bis(N-tosyl)sulfur diimide. The products are 1,2,4-benzothiadiazines (Scheme 14) (73ZOR2038, 68LA(715)223), and in the case of sulfur dichloride, chlorination of the aromatic ring also occurs. 1,2,4-Benzothiadiazines can also be prepared from N-arylamidines by reaction with sulfenyl chlorides or disulfides in the presence of NCS. Thus N-phenylben-zamidine and benzenesulfenyl chloride give the 1,2,4-benzothiadiazine (182) (78CC1049). 

A modification of the reaction of a-aminoacetonitrile (37a) has been developed which leads to 3,4-dichloro-l,2,6-thiafiiazole (39) in over 80% yield. The action of commercial sulfur dichloride on 37a produces a 1-1 mixture of 3-chloro- and 3,4-dichloro-l,2,5-thiadiazole, (38 and 39). However, if excess chlorine is added to the reaction mixture the dichloro compound forms exclusively in 82 % yield. It was shown that the dichloro compound does not form via chlorination of 3-chloro-1,2,5-thiadiazole. Therefore, either chlorination takes place on one of the intermediates prior to aromatization or the amino-acetonitrile is oxidized by the chlorine-sulfur dichloride mixture to cyanogen which is known to react with the sulfur chlorides to form 39 (see Section II,B,4). 

There are no systematic studies on the reaction of sulfur dichloride with polar organometallic reagents. The high reactivity of sulfur dichloride allows the couplings to be carried out at very low temperatures, even at —100 °C the reactions proceed almost instantaneously. The use of an excess of SC12 should be avoided, since this reactive molecule may easily add to the hetero-aromatic system or form an (unstable) sulfonium compound with the sulfur between the two heterocyclic units. 

Sulfurdiimides are obtained from aromatic amines and sulfur tetrafluoride. Heating of A-arylsulfonylimido dichlorides with aromatic amines affords A-aryl-A -sulfonylarylsulfurdiimides. The latter compounds are also formed in the stepwise replacement of the arylsulfonyl moiety in bis-arylsulfonylsulfurdiimides with aromatic amines. The [4+2] cycloaddition reactions of sulfurdiimides, which proceed in high yields, were extensively investigated. 

Methyl esters. A convenient method for the conversion of acids into their methyl esters involves refluxing the acid (1 mole) with methanol (3 moles), ethylene dichloride (300 ml., methylene chloride can also be used), and sulfuric acid (3 ml. for an aliphatic acid, 15 ml. for aromatic) for 6-15 hrs. (overnight is convenient). The reaction mixture is diluted with water, and the organic layer is washed with sodium carbonate solution and dried, and the solvent is removed. A number of aliphatic and aromatic acids afford methyl esters in yields of 87-98°%. ... 

In the sulfonation of the less reactive aromatic hydrocarbons or aryl halides, it is desirable to use 5-20% oleum, which brings about reaction at a convenient rate at moderate temperatures (0-50°) furthermore, if oleum is used, less sulfuric acid remains at the completion of the reaction to interfere with the isolation of the product. In the preparation of salts, however, this factor is of less significance. Although sulfur tiioxide is even more active than oleum, it can be used to advantage only occasionally because it favors the formation of a sulfone. The formation of by-products is decreased by use of a solvent a suitable solution can be prepared by passing the gaseous material, obtained by warming 60% oleum, into cold ethylene dichloride. 

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