Sulfur trioxide pyridine complex

Sulfur trioxide pyridine complex is the compound with the formula C₅H₅NSO₃. It is a colourless solid that dissolves in polar organic solvents. It is the adduct formed from the Lewis base pyridine and the Lewis acid sulfur trioxide. The compound is mainly used as a source of sulfur trioxide, for example in the synthesis of sulfate esters from alcohols:[1]

ROH + C₅H₅NSO₃ → [C₅H₅NH]⁺[ROSO₃]⁻

Sulfur trioxide pyridine complex

Identifiers
CAS Number	26412-87-3^Y
3D model (JSmol)	Interactive image
ChemSpider	147422^Y
ECHA InfoCard	100.043.334
PubChem CID	168533
CompTox Dashboard (EPA)	DTXSID50885349
InChI InChI=1S/C5H5N.O3S/c1-2-4-6-5-3-1;1-4(2)3/h1-5H;^Y Key: UDYFLDICVHJSOY-UHFFFAOYSA-N^Y InChI=1/C5H5N.O3S/c1-2-4-6-5-3-1;1-4(2)3/h1-5H; Key: UDYFLDICVHJSOY-UHFFFAOYAG
SMILES O=S(=O)=O.n1ccccc1
Properties
Chemical formula	C5H5NSO3
Molar mass	159.16 g/mol
Appearance	white solid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

The compound is used for sulfonylation reactions, especially in the sulfonylation of furans.[2] It is also an activating electrophile in a Parikh-Doering oxidation.[3]

References

1. Thomas T. Tidwell "Sulfur Trioxide–Pyridine" Encyclopedia of Reagents for Organic Synthesis 2001, John Wiley & Sons. doi:10.1002/047084289X.rs139m. Article Online Posting Date: April 15, 2001
2. Spivey, Alan (12 March 2012). "Heteroaromatic Chemistry Lectures 4 and 5" (PDF). Imperial College Research. Retrieved 7 February 2017.
3. Jekishan R. Parikh, William v. E. Doering (1967). "Sulfur trioxide in the oxidation of alcohols by dimethyl sulfoxide". J. Am. Chem. Soc. 89 (21): 5505–5507. doi:10.1021/ja00997a067.

Further reading