Catechol Sulfate

[4074-55-9]  · C6H4O4S  · Catechol Sulfate  · (MW 172.16)

(selective reagent for the conversion of amines to sulfamate salts4 and sulfamides;9 mild reagent for sulfonation of carbon acids16)

Alternate Name: pyrocatechol cyclic sulfate; 1,3,2-benzodioxathiole 2,2-dioxide.

Physical Data: mp 35.5-36 °C; bp 76-78 °C/1.25 mmHg.4

Solubility: Sparingly sol water and hexane; sol most organic solvents.

Form Supplied in: white solid or colorless needles.

Preparative Method: reaction of catechol with SO2Cl2.4

Purification: distillation and recrystallization (hexane).

Handling, Storage, and Precautions: stable indefinitely at ambient temp; no information available on toxicity.

The reactivity of catechol sulfate (CS) with hydroxide ion is anomalous relative to other sulfuric acid diesters. Surprising is the very high rate of cleavage1 and that only S-O fission is observed.2 X-ray crystal data suggest this unusual reactivity to be due to ring-strain effects and a distorted nonplanar conformation.3

Conversion of Amines to Sulfamate Salts.

Amines may be cleanly converted to catecholyl esters of sulfamic acids on reaction with CS.4 These readily isolable esters may be efficiently hydrolyzed on mild alkaline treatment. This two-step process affords greater selectivity than possible with other reagents such as ClSO3H and SO3 complexes,5 fuming H2SO4,6,7 and SO2Cl2/SbCl5.8 As example of the selectivity observed with CS, amine (1) is quantitatively converted to ester (2) which is then cleanly hydrolyzed to sulfamate salt (3) (eq 1). In contrast, while reaction of (1) with Me3N/SO3 gives (3) directly, it is formed as a minor component (15-20%) of a complex mixture. Ester (2) is then cleanly converted to (3) by reaction with alkali.

The CS sulfamation procedure is limited to primary aliphatic amines. Aromatic amines react only slowly with CS and secondary amine/CS condensation products are not cleaved by alkali.

Conversion of Amines to Sulfamides.

Catecholyl sulfamate esters, which are available as described above, may be combined with a second amine to provide sulfamides.9 Other known procedures for sulfamide preparation employ strongly electrophilic agents such as SO2Cl2.10-13 The two-step CS procedure is advantaged in its selectivity and in that either symmetrical or unsymmetrical sulfamides may be obtained. It is limited in that the amine which reacts with CS must be primary and thus tetrasubstituted products cannot be obtained directly. Sulfamides of the type R1R2NSO2NH2 have been prepared by using a primary amine in which the alkyl substituent is acid labile (e.g. 4-MeOPhCH2).14 Exemplary of the two-step CS sulfamide methodology is the preparation of (4) (eq 2).

Conversion of Carbon Acids to Sulfonate Salts.

Reaction of a carbanion with CS yields the catecholyl ester of a sulfonic acid. The ester is easily hydrolyzed with alkali to give the desired sulfonic acid salt.15 This procedure is selective and the intermediate esters may easily be isolated in pure form. Carbon acids may also be sulfonated by SO3 and various of its complexes.16 However, the yields are generally low and the desired products difficult to obtain in pure form. Exemplary of CS sulfonation is the preparation of substituted methionic acid (5) (eq 3).15

Related Reagents.

Chlorosulfonic Acid; ; Sulfur Trioxide; ; Sulfuryl Chloride.

1. Kaiser, E. T.; Katz, I. R.; Wulfers, T. F. JACS 1965, 87, 3781.
2. Kaiser, E. T.; Zaborsky, O. R. JACS 1968, 90, 4626.
3. Boer, F. P.; Flynn, J. J. JACS 1969, 91, 6604.
4. DuBois, G. E.; Stephenson, R. A. JOC 1980, 45, 5371.
5. Gilbert, E. E. Sulfonation and Related Reactions; Interscience: New York, 1965; Chapter 7.
6. Bieber, T. JACS 1953, 75, 1405.
7. Bieber, T. JACS 1953, 75, 1409.
8. Weiss, G.; Schulze, G. LA 1969, 729, 40.
9. DuBois, G. E. JOC 1980, 45, 5373.
10. Dorlars, A. MOC 1958, XI/2, pp 711.
11. Andersen, K. K. In Comprehensive Organic Chemistry, Barton, D. H. R., Ollis, W. D., Eds.; Pergamon: New York, 1979; Vol. 3, pp 363-365.
12. Spillane, W. J. IJSB 1973, 8, 469.
13. Gilbert, E. E. Sulfonation and Related Reactions, Interscience: New York, 1965; Chapter 7.
14. Lee, C.-H.; Lee, M. S.; Lee, Y.-H.; Chung, B. Y. Bull. Korean Chem. Soc. 1992, 13, 357.
15. DuBois, G. E.; Stephenson, R. A. JMC 1985, 28, 93.
16. Gilbert, E. E. Sulfonation and Related Reactions, Interscience: New York, 1965; pp 33-61.

Grant E. DuBois

The Coca-Cola Company, Atlanta, GA, USA

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