Ankie Koeberg-Telder

Solutes in sulphuric acid. Part VI. A nuclear magnetic resonance study of organic sulphonic acids and 1H nuclear magnetic resonance standards; pKBH determination of sulphonic acids

The behaviour of some alkane- and arene-sulphonic acids in sulphuric acid as solvent has been investigated. In aqueous sulphuric acid the sulphonic acids ionize: ArSO3H ⇌ ArSO3–+ H+. The ionization follows the H0a acidity function and half-ionization is observed at –5·8 > Hoa > –6·8. In fuming sulphuric acid the sulphonic acids exhibit both protonation and sulphur trioxide complexation with formation of RSO3H2+ and RS2O6H respectively. The chemical shifts of some 1H n.m.r. standards for the sulphuric acid system are reported. The preferred standards are the (CH3)4N+ ion as internal standard, and neat liquid tetramethylsilane as external standard.

Aromatic sulphonation. Part 77. Sultone and 1,3,2,4-dioxadithian 1,1,3,3-tetraoxide formation in the sulphonation of 3-phenylpropan-1-ol

Reaction of 3-phenylpropan-1-ol (1) in concentrated sulphuric acid leads initially to the formation of mainly 3-(p-sulphophenyl)propyl hydrogensulphate (3a) and ca. 12% of the ortho-isomer (3b). Compound (3a) is slowly converted into the geometrically isomeric dioxadithian tetraoxides (6a) and (7a) which eventually yield (E)-1-(p-sulphophenyl)prop-1-ene-2-sulphonic acid (4a). Compound (3b) eventually yields via the sultone (8), a detectable and isolable intermediate and the dioxadithian tetraoxides (6b) and (7b). Reaction of (1) with SO3 in nitromethane leads to the formation of the para-sulpho isomer (3a) which is slowly converted into (6a) and (7a) as stable products in the reaction system. Mechanisms for the formation of the various products in the two sulphonating systems are proposed, and the differences in mechanism discussed.

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

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% H2SO4A 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.

Aromatic sulphonation. Part L. Sulphonation of the trimethylbenzenes: isomer distributions and hydrogen kinetic isotope effect

Isomer distributions for the sulphonation of 1,2,3- and 1,2,4-trimethylbenzene with concentrated aqueous sulphuric acid at 25.0° have been determined. The results are discussed in terms of sulphonation by H3SO4+ and H2S2O7 as sulphonating entities. The isomer distributions for the H2S2O7 mechanism are 90 ± 1% 4- and 10 ± 1% 5- substitution for the 1,2,3-isomer and 75 ± 2% 5- and 25 ± 2% 6-substitution for the 1,2,4-isomer, those for the H3SO4+ mechanism are 86 ± 1% 4- and 14 ± 1% 5-substitution with the former isomer andd 89 ± 2% 5- and 11 ± 2% 6-substitution by the latter. The deviations of the observed isomer distributions and of the partial rate factors for the H3SO4+ mechanism from those calculated on the basis of the additivity principle are discussed. The sulphonation of 1,3,5-trimethylbenzene with sulphur trioxide proceeds without a primary hydrogen kinetic isotope effect, kH/kD being 1.15 ± 0.13 and 0.98 ± 0.09 for nitromethane at 0° and trichlorofluoromethane at –35° respectively.

Aromatic sulphonation. Part XLIV. Sulphonation of some meta-substituted benzenesulphonic acids with fuming sulphuric acid. Preparation of arene-1,2-disulphonic anhydrides

Isomer distributions for the sulphonation of various 3-substituted benzenesulphonic acids in fuming sulphuric acid at 25° have been determined. The isomer distributions are dependent on the sulphuric acid concentration and approach a constant ratio below 104 and above 115% H2SO4. The degree of substitution at the 6-position and the f6:f5 partial rate factor ratio run parallel with the ability of conjugative electron release of the substituent at the 3-position. The size of this substituent further determines the f4:f6 ratio. The preparation of some 4-substituted benzene-1,2-disulphonic anhydrides is described. They hydrolyse rapidly with the exception of 3,4,5,6-tetramethylbenzene-1,2-disulphonic anhydride. This compound is also formed more rapidly from the corresponding disulphonic acid than the other anhydrides, probably as a result of a decrease in overcrowding. The 1H n.m.r. and i.r. spectral data of the intramolecular anhydrides are compared with those of some intermolecular arenesulphonic anhydrides.

SULFUR TRIOXIDE SULFONATION OF DIPHENYL ETHER, DIPHENYL SULFIDE, DIBENZO[B, E][1, 4]DIOXIN, AND XANTHENE

Abstract The sulfur trioxide sulfonation of diphenyl ether (1), diphenyl sulfide (2), and the related tricyclic dibenzo-[b, e][1, 4]dioxin (3) and xanthene (4) has been studied. The substrates 1 and 2 both yield initially the 4-sulfonic acid derivative (4-S) and subsequently the 4, 4′-S2. In a large excess of 104.5 wt-% H2SO4 the further sulfonation of 1-4, 4′-S2 gave the 1-2, 4, 4′-S3 and subsequently some 1-2, 4, 2′,4′-S4. Sulfonation of the dibenzodioxin 3 with 4.0 mol-equiv. of SO3 gave the 2-S derivative, whereas with 12.0 mol-equiv. of SO3 a mixture of the 2, 7-S2 and 2, 8-S2 was obtained in yields of 57 and 43%, respectively. Sulfonation of xanthene (4) with 4.0 mol-equiv. of SO3 yielded the 2, 7-S2 derivative.

SULFONATION AND SULFATION IN THE REACTION OF 4-METHYLPHENOL WITH CONCENTRATED SULFURIC ACID

Abstract The sulfonation of 4-methylphenol (1) in concentrated sulfuric acid ranging in concentration from 81.6–112.2% H2SO4 has been studied. In ≤98.5% H2SO4 the initial product is exclusively the 2-sulfonic acid (1-2-S) and the eventual one 1-2,6-S2. In fuming sulfuric acid, the additional products are the cyclic sulfate sulfonate anhydride 2, 2-5-S, 2-6-S and 2-3,5-S2. The precursor of 2-5-S is 2 and that of 2-6-S 1-2,6-S2. In 112.2% H2SO4 2-5-S yields slowly 2-3,5-S2 [(cf. Scheme 1)

Aromatic sulphonation. Part 94. Sulphonation and sulphation of the three 2- and 4-hydroxy- and 2- and 4-methoxy-benzenesulphonic acids in concentrated sulphuric acid

The sulphonation of 2-methoxy-(1) and 4-methoxy-benzene sulphonate (2) and 1-(3), 3-(4), and 4-hydroxybenzenesulphonate (5) in 86.9–98.5% H2SO4 at 25 °C has been studied. Substrates (1)–(3) and (5) all yield the corresponding 2,4-disulphonic acid as the exclusive product, whereas (4) yields a mixture of 2-hydroxybenzene-1,4- and 4-hydroxybenzene-1,2-disulphonic acid. 3- and 4-Hydroxybenzenesulphonic acids in sulphuric acid (>87% H2SO4) are present in part as their hydrogen sulphates and the sulphuric acid concentration of 50% sulphation is 97.5 and 100.5 ± 0.2% H2SO4. The sulphonation is first order in the aromatic substrate. From the rate dependence on the sulphuric acid concentration it is concluded that the substrate species undergoing ring sulphonation is the –O3SC6H4OR (R = H; Me) species with H2S2O7 as the sulphonating entity. From the observed proportionality between [–O3SC6H4OSO3H]/[–O3SC6H4OH] and aSO3 it is concluded that the aromatic species undergoing sulphation is again –O3SC6H4OH.

Aromatic sulphonation. Part 71. Sulphonation and protonation of 1,2-diphenylcyclopropenone

The oxygen protonation and the phenyl substitution of 1,2-diphenylcyclopropenone in sulphuric acid as well as the sulphur trioxide sulphonation in CCl3F as solvent have been studied. 1,2-Diphenylcyclopropenone is half protonated at ca. 63 wt-% H2SO4. Sulphonation in 105 wt-% sulphuric acid yields the 1,2-diphenylcyclopropenone-3′,3″-disulphonic acid. The sulphonation with 5 equivalents of sulphur trioxide in CCl3F led to a substrate conversion of 64% with formation of 45 ± 3% 3′-sulphonic acid and 19 + 3% 3′,3″-disulphonic acid. The entity undergoing substitution in fuming sulphuric acid is identified as it is for aprotic sulphonation.

Aromatic sulphonation. Part 54. Sulphonation of polyethylbenzenes. On the Jacobsen rearrangement of the tetraethylbenzenesulphonic acids

The reaction of m- and p-di-, 1,3,5-tri-, and 1,2,3,5- and 1,2,4,5-tetra-ethylbenzene with concentrated aqueous sulphuric acid leads to clean sulphodeprotonation. m-Diethylbenzene in 95.2% H2SO4 at 25° gives 9% 2-, 90% 4-, and ⩽3% 5-substitution. The monosulphonic acids obtained from the di- and tri-ethylbenzenes are stable in the sulphonation media. In contrast the sulphonic acids obtained from 1,2,3,5- and 1,2,4,5-tetraethylbenzene are unstable in 98.4% H2SO4 and are eventually converted into 2,3,4,5-tetraethylbenzenesulphonic acid. The least stable acid is the 2,3,5,6-isomer which rearranges in part via the 2.3,4,6-isomer and in part directly to the 2,3,4,5-isomer by 1,2-ethyl shifts of the appropriately ring protonated arenesulphonic acids.