ISSN:
0947-3440
Keywords:
SO3 sulfonation
;
Arenesulfonic acids
;
Arenesulfonic anhydrides
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
An exploratory study has been made on the SO3 sulfonation of a number of alkylarenes in [D2]dichloromethane as an aprotic solvent, mostly in the presence of [D8]1,4-dioxane as a reactivity moderator, in order to obtain information on sulfonic acid and sulfonic anhydride formation. 1,2-Dimethylbenzene (1) with 1.0 mol-equiv. of SO3 yields predominantly the 4-sulfonic acid (1-4-S), whereas with 4.0 mol-equiv. of SO3, 18 mol-% of the corresponding (intermolecular) sulfonic anhydride (1-4-SO2)2O is additionally formed. 1,4-Dimethylbenzene (2) with 0.8 mol-equiv. of SO3 yields predominantly 2-2-S, whereas with 4.0 mol-equiv. of SO3 the sulfonic anhydride (2-2-SO2)2O and its 6-S and 6,6′-S2 derivatives are formed, the eventual main product being (6-S-2-2-SO2)2O. Reaction of 1-ethyl-4-methylbenzene (3) with 2.0 mol-equiv. of SO3-[D8]dioxane at -78 → -40 °C leads to the predominant formation of the 2- and 3-S derivatives in a molar ratio of 26:74, with small amounts of the three corresponding intermolecular anhydrides. Upon performing the sulfonation of 3 at 0 → 22 °C, the relative amounts of the anhydrides are larger, and in addition the 3,5-S2 derivatives of the intermolecular anhydrides are formed. The absence of the isomeric 2,6-S2 derivative is ascribed to the buttressing effect of the 2-sulfo on the 1-ethyl group, hampering the sulfonation at C(6). Reaction of diphenylmethane (4) with 4.2 mol-equiv. of SO3 at -20 → 25 °C yields initially 4-4′-S and subsequently 4-4′,4″-S2. Sulfonation of 1,2-diphenylethane (5) with 4.0 mol-equiv. of SO3 at -78 → 22 °C for 4.5 h leads mainly to the cyclic dimeric disulfonic anhydride [5-4′,4″(-SO2)2O]2, which upon hydrolysis affords 9% of 5-2′,4″- and 91% of 5-4′,4″-S2. However, sulfonation of 5 at 0 → 22 °C for ca. 0.8 h was found to lead to the formation of the intermolecular sulfonic anhydride (4′-S-5-4″-SO2)2O. On sulfonation of 1,2-di-p-tolylethane (6) with 1.0 mol-equiv. of SO3, only ca. 20% of the substrate was sulfonated to give, after hydrolysis, 3% of the 2′- and 12% of the 3′-sulfonate, whereas with 4.0 mol-equiv. of SO3 the initial monosulfonic acids are almost completely converted to yield the 2′,3″,5″-S3, 3′,3″,5″-S3, and 3′,3″,5′,5″-S4.
Additional Material:
9 Tab.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199719971109
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