Herz reaction

Treatment of anilines with sulfur monochloride to produce thiazothionium chlorides, which upon treatment with base give a-aminothiophenols. 

Valentin, J. Justus Justus Liebigs Ann. Chem. 1966, 699,183. 

Grandolini, G. Perioli, L. Ambrogi, V. Gazz. Chim. Ital. 1997, 727,411. 

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The most important reaction of disulfur dichloride (S2C12) is with primary arylamines—the Herz reaction (Scheme 4). The Herz reaction has been reviewed and the mechanism of formation of the intermediates discussed.35 Heteroaromatic primary amines react in similar fashion.36... 

Reaction of l-methyl-4-aminoimidazole (71 R1 = Me, R2 =H) with sulfur monochloride (S2C12) gave a product that was isolated and assumed to be the imidazo[4,5-c/]-l, 2,3-dithiazole (91) (56%) by analogy with other hetero-Herz reactions (84JOC1224). 

The thiadiazolo[3,4-g] indole 100 was prepared from 4-amino-5-chlorobenzothiadiazole 99 by treatment with pyruvic acid in the presence of [Pd(But3P)2] (Equation 14) <2004AGE4526>. The Herz reaction of 4-aminoben-zothiadiazole 101 with disulfur dichloride gave the fused 1,2,3-dithiazolium chloride 102, which was condensed with malononitrile to give the ylidene 103 (Scheme 15) <2002J(P1)315>. 

While the Herz reaction provides a convenient route to many dithiazolylium salts, the propensity for chlorination of the aromatic substituent has led to the development of several other approaches to 1,2,3-dithiazolylium salts and... 

Substituted thioindigoid dyes are usually obtained via the appropriate benzenethiol in a Heumann-type synthesis. The final cyclisation of the phenylthioglycolic acid derivative can often be achieved in concentrated sulphuric acid or by using chlorosulphonic acid. Several routes make use of the Herz reaction (Scheme 6.22), in which a substituted aniline is converted into the corresponding o-aminothiophenol by reaction with sulphur monochloride followed by hydrolysis of the intermediate dithiazolium salt [47]. After reaction between the thiol and chloroacetic acid, the amino group is converted into a nitrile group by a Sandmeyer reaction. Hydrolysis of the nitrile leads to the formation of the required thioindoxyl derivative. 

This review is divided into sections depending on the quantity of sulfur atoms in the formed heterocycle. We have examined all the literature data for the last 150 years up to March 2007, including the latest achievements concerning 1,2,3-dithiazoles fused with other heterocycles. We do not discuss the Herz reaction since it is well known and has been reviewed (1957CRV1011). 

A series of condensed 1,2,3-dithiazoles were prepared by Oakley and coworkers from o-aminoaromatic and heterocyclic thiols and S2CI2. This approach is more beneficial than a common Herz reaction that fails when applied to some aromatic amines, especially to phenylenediamines (1999JA969 Scheme 59). 

Synthesis of 1,2,3-dithiazoles is the most extensively studied. The widely used and very long-known Herz reaction of arylamines with S2CI2 to give benzo-l,2,3-dithiazolium salts (Section 4.11.8.5) has been extended to hetarylamines (Scheme 17). More importantly, a new impetus for its investigation and development was provided when benzo-l,2,3-dithiazolyl radicals were shown by Mayer and co-workers to be intermediates. The reaction in a modified form was transformed by the above authors to an effective method for synthesis of this new class of stable radicals. When applied to acyclic enaminoketones the thiosulfinylamine precursor of the free radical could be isolated (Scheme 18). It was also extended to cyclic and acyclic oximes to afford fused and monocyclic... 

O-Mercaptohetarylamines were converted to condensed dithiazoles this approach is successful in some cases where Herz reaction fails. Bis( 1,2,3-dithiazoles) can be obtained by this method which is one of the most important developments in the chemistry of dithiazoles. 

Based on previous work with sulfur monochloride, a reaction pathway leading to 1,2,5-thiadiazole from sulfur monochloride was postulated. Reactions of sulfur monochloride indicate that the molecule can be polarized as C1SS +—Cl and in several instances compounds containing the chlorodithio group (CISS—) have been isolated. Chlorodithio compounds have also been postulated as intermediates in the reaction of aliphatic amides with sulfur monochloride leading to bisamidosulfides and in the Herz reaction. It has also been reported that under the conditions of the Herz reaction o-phenylenediamine is converted to 2,1,3-benzothiadiazole and in this case it appears that the intermediate iV -chlorodithio compound is cleaved at the S—S bond by nucleophilic attack by the ortho amino group, Eq. (1). A similar process was proposed for the formation of... 

In addition, sulfur monochloride (37) will react with p-chloroarylamines, like (45) in the presence of sodium hydroxide to give the sodium thiophenolate (46) this is the Herz reaction (Scheme 31) used in the synthesis of o-aminothiophenols, which are useful in the manufacture of thioindigo dyes (see Chapter 11, p. 221). 

Herz reaction Herz compounds. Formation of o-aminothiophenols by heating aromatic... 

When primary aromatic amines are treated with sulphur monochloride (8202 > also known as disulphur dichloride)—the Herz reaction—one or more products may be formed. One of these, the benzothiazathiolium salt, on treatment with nitrous acid gives the benzothiadiazole. Depending on the type of substitution in the ring, it is possible to obtain a good yield. The benzene ring may be chlorinated simultaneously, and the thiadiazole may possibly rearrange to another five-membered ring. 

Treating the hydrochlorides of primary aromatic amines with an excess of disulfur dichloride (the Herz reaction)252 and hydrolysing the resulting thiazthionium chlorides with alkali afford 0-aminothiophenols.253 If the amine has the /wra-position free, the product is a 5-chloro-2-aminothiophenol. 

Other references related to the Herz reaction are cited in the literature. ... 

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