Nitrobenzene, chlorosulfonation

The unavoidable excess of sulfuric acid in sulfonation reactions using sulfuric acid or oleum causes, under some conditions, such undesirable side reactions as further sulfonation or rearrangement of the sulfonic acid formed initially. These difficulties can be avoided by effecting the sulfonation with the calculated quantity of chlorosulfonic acid in an organic solvent which is not attacked by this reagent (usually nitrobenzene). For further details on this method, see the preparation of 2-naphthol-l-suIfonic acid, page 199. 

Indanthrene blue RS dyes cotton a pure, deep blue from its blue hydrosulfite vat. The dye has exceptional light fastness. Its fastness to chlorine is only moderate, but this can be improved by chlorination. This cUorination can be effected by the action of chlorine on the sulfuric acid solution in the presence of sodium nitrite (GCD brand), by the action of sulfuryl chloride on the nitrobenzene solution (BCS brand), or by the action of chlorine in chlorosulfonic acid, possibly in the presence of a carrier such as iron chloride or antimony pentachloride. 

Aromatic aldehydes are prepared by passing carbon monoxide and dry hydrogen chloride through an ether or nitrobenzene solution of an aromatic hydrocarbon in the presence of a catalyst, commonly aluminum chloride with cuprous chloride as a carrier. The process is illustrated by the synthesis of p-tolualdehyde (51%). A convenient procedure for obtaining an equimolar mixture of anhydrous hydrogen chloride and carbon monoxide consists in dropping chlorosulfonic acid on formic acid, viz.,... 

A mixture of 123 g. (1.0 mole) of dry nitrobenzene and 350 g. (3.0 moles) of chlorosulfonic acid is stirred, and the temperature is raised gradually to 100° and maintained there for 2 hours. (Hood.) The temperature is then raised to 110-120° for 6 hours, followed by a 2-hour period at 125-130°. The cooled mixture is poured into a slurry of 1 kg. of crushed ice and 1 kg. of water. The precipitated... 

Chlorosulfonic acid, 0ISO3H, is a liquid boiling at 152 C. It dissolves readily in chloroform, carbon tetrachloride, nitrobenzene, and liquid SO2 these solvents are sometimes used with this reagent both industrially and... 

Biphenyl and Derivatives (Table VII). Biphenyl-4-sulfonic acid can be prepared very satisfactorily by sulfonation with sulfuric acid in nitrobenzene solution (90% yield) or by the action of chlorosulfonic acid in tetrachloroethane at 50°." Sulfuric acid alone either gives a mixture of the 4-mono- and 4,4 -di-sulfonic adds with unchanged hydrocarbon or, with excess reagent, yields chiefly the di- derivative. The monosulfonic acid is readily freed from the disulfonic acid through its sparingly soluble copper salt the disulfonic acid remains in solution and can be crs stallized... 

Naphthalene. Early studies showed that the action of slightly less than one equivalent of chlorosulfonic acid on a 10% solution of naphthalene 40 in carbon disulfide gives the 1-sulfonic acid and a little of the 1,5-disulfonic acid, but none of the 2-sulfonic acid was isolated. Naphthalene has also been reacted with chlorosulfonic acid in nitrobenzene and in nitrotoluene at 20-35 °C. With an equimolar quantity of the reagent, a mixture of the mono-sulfonic acids and dinaphthyl sulfones was formed at 6°C, the 1,1-sulfone predominated, but at 170 °C, the 2,2 -isomer was the major product. The reaction has also been extensively studied at low temperatures (—35 to 0 °C). ... 

Methylnaphthalene reacts with chlorosulfonic acid in nifrobenzene at 30-40 °C to yield the 8-sulfonic acid. 1-Benzylnaphthalene with the reagent in nitrobenzene solution at room temperature affords the 4-sulfonic acid as the sole product and 1,8-dibenzylnaphthalene with hot chlorosulfonic acid (100-110 °C) also probably gives the 4-sulfonic acid. ... 

Chrysene 47 with chlorosulfonic acid at low temperature affords the 2-sulfonic acid which is useful as dye intermediate. Triphenylene 48 reacts with chlorosulfonic acid in nitrobenzene to yield triphenylenesulfonic acid. ... 

The formation of oligoanthracenes was observed during mild sulfonation of 49 by chlorosulfonic acid (one equivalent) in nitrobenzene solution at 50 C (3 hours). On the other hand, a similar reaction in acetic acid at 70 °C only afforded water-soluble sulfonic acids and the possible mechanisms of polymerization of anthracene were discussed. ... 

In l-chloro-2-nitrobenzene, sulfonation by excess chlorosulfonic acid occurred para to the chlorine atom as would be anticipated " and with l-chloro-4-nitrobenzene, the expected product, namely 2-chloro-5-nitrobenzenesulfonyl chloride, was also obtained. ... 

In the aryl nitro compounds, the powerful electron-withdrawing (—1, -M) effect of the nitro group results in the sulfonation of nitrobenzene being more difficult than that of benzene. Early work claimed that heating nitrobenzene with excess chlorosulfonic acid (two equivalents) afforded m-nitrobenzenesulfonyl chloride, but under drastic conditions (150 °C, 20 hours) the only product was reported to be tetrachloro-/>-benzoquinone (chloranil). 

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