ISSN:
0018-019X
Keywords:
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The reaction of 2-naphthol-1-sulfonic acid with diazonium salts was investigated in the pH range 10 to 15. The structures postulated for the reaction products by Rowe et al. [3] and by Koller [4] were proved by instrumental analysis. In alkaline solutions, instead of the usual diazodesulfonation reaction, addition of an hydroxyl ion to the σ-complex formed from 2-naphthol-l- sulfonic acid and substituted diazonium salts takes place. The resulting intermediates undergo heterolytic fragmentation leading to substituted o-(phenylhydrazono-sulfo-methy1)-cinnamicacids 7. The kinetic measurements prove that one equivalent of water is added during this fragmentation. 7 is produced by a conrotatory ringopening of the σ-complex. An intramolecular ring closure in the formation of 8 from 7, results from studies of NMR. spectra, and molecular models show that both exocyclic double bonds in 7 have cis-configuration. Kinetic measurements demonstrate that it is the anion 11 which enters the ring closure reaction: After intramolecular nucleophilic attack of the anionic nitrogen upon the double bond of the cinnamic group, a proton is added stereospecifically. The fragmentation of the σ-complex is a competitive reaction to the release of the elctrofngal leaving group in electrophilic aromatic substitution. The fragmentation is dominant in this case because the electrofugal leaving group is not a proton but a SO, molecule. The conditions (constitution of reagents, catalysts, etc.) which influence the ratio of the two competitive reactions of cyclohexadienone-type σ-complexes are discussed.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/hlca.19710540853
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