Rearrangement Jacobsen

Treatment of polyalkylbenzenes or polyhalobenzenes with concentrated sulfuric acid to give rearranged and sulfonated polyalkylbenzenes or polyhalobenzenes. 

Aromatic Rearrangement Elsevier New York, 1967, pp 23-32, 48-55. (Review). 

Solari, E. Musso, F. Ferguson, R. Floriani, C. Chiesi-Villa, A. Rizzoli, C. Angew. Chem., Int. Ed. Engl. 1995,55, 1510. 

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Diiodoanisole is also formed in this reaction, which has been taken178 as evidence that the reaction is intermolecular. Halogen migration during sulphonation (Jacobsen rearrangement) is also well-known163. 

In the sulfonation of polyalkylbenzenes such as 1,2,4,5-tetramethylbenzene (29) intramolecular migration of an alkyl group (Jacobsen rearrangement, 1886) may occur prior to sulfonation, so that the product is 2,3,4,5-tetramethylbenzenesulfonic acid (30) in which the alkyl groups have moved closer together (Scheme 17). The Jacobsen rearrangement is restricted to tetra- and pentaalkylbenzenes. 

Jacobsen Rearrangement. When a polyalkylated benzene is allowed to remain in contact with sulfuric acid, a rearranged polylalkylbenzene sulfonic acid is often obtained. Reactions of this kind are usually called Jacobsen rearrangements.54 The reaction of durene with sulfuric acid is an example ... 

For a review of the Jacobsen rearrangement, see Smith in Adams, Organic Reactions, Vol. I, p. 370, John Wiley and Sons, New York, 1942. 

JACOBSEN Rearrangement Akyl group migration in aromatic systems. 

JACOBSEN Rearrangement Alky) group migration In aromatic systems. 

The individual 2,3,4,6- and 2,3,5,6-tetramethylbenzenesulphonic acids themselves isomerize in 98.4% H2S04 to the 2,3,4,5-isomer via series of reactions similar to those outlined in Scheme 218. In contrast, tetraethylbenzenesulphonic acids undergo a Jacobsen rearrangement in 98.4% H2S04 that involves [l,2]-shifts of the ethyl group19. Thus, both... 

Other references related to the Jacobsen rearrangement are cited in the literature. ... 

Jacobsen Epoxidation Jacobsen Rearrangement Janovskv Reaction Japp-Klingemann Reaction Jauregg (see Wagner-Jauregg Reaction)... 

Alkyl Migration (Jacobsen Rearrangement) The Jacohsen rearrangement is the migration of an alkyl group within a polyalkyl- or polyhalo-arylsulfonic acid (Scheme 18.26, 168 169). 

Apphcations of the reaction have been seen in the rearrangement of tetraethylbenzenesulfonic acids [85], wherein the reaction of meta- and para-di-, 1,3,5-tri- and 1,2,3,5- and 1,2,4,5-tetra-ethylbenzenes with concentrated aqneous sulfuric acid leads to clean sulfodeprotonation. Recent examples by Solari et al. witnessed a catalytic variation of the Jacobsen rearrangement using ZrCl [86]. The rearrangement, previously only observed in concentrated sulfuric acid, appeared to be extremely mUd under ZrCl -mediated conditions on permethylated arenes at room temperature in halogenated solvents. 

A number of polyalkylbenzene derivatives not directly available by the Friedel-Crafts procedure may be prepared by appUcation of the Jacobsen rearrangement. " ... 

J acid urea urea del acido J jacketed encamisado Jacobsen rearrangement transposicion de Jacobsen... 

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