| Popis: |
Proton magnetic resonance spectra of a number of simple alkenesulfonic acids and related hydroxyalkanesulfonic acids have been measured. The compound described in the literature as 2-methylpropene-1,3-disulfonic acid (I) has been found to be 2-methylenepropane-1,3-disulfonic acid (II). Interconversion of I and II and of the 1- and 2-propene-1-sulfonic acids can be effected at 100° in 1N-sodium hydroxide as well as concentrated sulfuric acid. The equilibration of 2-propene-1-sulfonic acid and the hydrogen sulfate of 2-propanol-1-sulfonic acid in sulfuric acid is much faster than the equilibration of these two compounds with 1-propene-1-sulfonic acid and is thought to involve intramolecular catalysis. Double-bond isomerization of 2-methyl-2-propene-1-sulfonic acid can only be effected under alkaline conditions since this compound reacts rapidly with sulfuric acid to give eventually the disulfonic acids. Equilibrium constants for isomeric α,β- and β,γ-unsaturated sulfonic acids are reported. The base-catalysed isomerizations are much slower than the hydrogen-deuterium exchange of the α-hydrogens; the rate of acid-catalysed exchange of both types of hydrogens in II is about the same as that of the double-bond migration. |
