Aromatic sulphonation. Part 52. Ionization, sulphation, sulphonation, and alkylation of ω-phenylalkan-1-ols in sulphuric acid

Abstract

The reaction of a series of phenylalkanols of the general structure Ph[CH₂]_nOH (n= 2,3,4,5,6, and 10) in concentrated aqueous sulphuric acid at 25 °C has been studied. At acid concentrations >50% H₂SO₄ protonation dod sulphation of the alkanols take place. Half-protonation of 2-phenylethanol occurs at 75 ± 0% H₂SO₄. The rate constants for the sulphation of the alkanols and for the hydrolysis of the corresponding hydrogen sulphates increase with increasing acid concentration and so does the hydrogen sulphate/alkanol equilibrium ratio.

The degree of ortho-substitution in the sulphonation has been determined in the range of 87.6–98.4% H₂SO₄, and partial rate factors for ortho- and pare-substitution are reported for 90.2% H₂SO₄

A complication with 2-phenylethanol in 84–95% H₂SO₄ is the formation of poly(xylylenes)(mainly para-bridged) with 2-(p-phenylene)ethyl hydrogen sulphate and possibly 2-(p-phenylene)ethanol as terminal groups.

3-(p-Sulphophenyl)propyl hydrogen sulphate in 98.4% H₂SO₄ at 25 °C is eventually completely converted into 1-(p-sulphophenyl)prop-1-ene-2-sulphonic acid, whereas 5-(sulphophenyl)pentyl and 6-(sulphophenyl)-1-hexyl hydrogen sulphates in 90% H₂SO₄ at 25 °C are finally completely converted into 1-methyl- and 1-ethyl-1.2.3,4-tetrahydronaphthalene-7- and -5-sulphonic acid, respectively.