Kinetics of sulfonation of 4-hydroxyazobenzene

Autor:	E. Buncel, W. M. J. Strachan
Rok vydání:	1969
Předmět:	Computational chemistry Chemistry Scientific method Organic Chemistry Kinetics 4-hydroxyazobenzene Organic chemistry Protonation General Chemistry Catalysis
Zdroj:	Canadian Journal of Chemistry. 47:4011-4019
ISSN:	1480-3291 0008-4042
DOI:	10.1139/v69-667
Popis:	Spectral changes exhibited by 4-hydroxyazobenzene in the 90–100% H2SO4 region are shown to be the result of a sulfonation process, superimposed (above 98% H2SO4) on a second equilibrium protonation. The reaction product is 4-hydroxyazobenzene-4′-sulfonic acid. The rate of this sulfonation reaction increases by a factor of 500 over 91.7–100.0% H2SO4. The increase in rate is more gradual in acid media in which diprotonation of reactant is effective.In 100% H2SO4 and above, a second, much slower, rate process is discerned from the spectral changes in this system and is probably the result of a further sulfonation of 4-hydroxyazobenzene-4′-sulfonic acid. Kinetic data for this reaction are reported for 99.99–100.76% H2SO4.The results are in agreement with previous qualitative reports on the formation of sulfonation products from 4-hydroxyazobenzene or from azoxybenzene, its precursor in the Wallach rearrangement. The mechanism of the consecutive sulfonation reactions is discussed.
Databáze:	OpenAIRE
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