Sulfur trioxide pyridine complex

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| verifiedrevid = 450637936

| ImageFileL1 = Sulfur-trioxide-pyridine-complex-2D-skeletal.png

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| ImageFileR1 = Sulfur-trioxide-pyridine-complex-3D-vdW.png

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|Section1={{Chembox Identifiers

| CASNo_Ref = {{cascite|correct|??}}

| CASNo = 26412-87-3

| PubChem = 168533

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| ChemSpiderID = 147422

| SMILES = O=S(=O)=O.n1ccccc1

| InChI = 1/C5H5N.O3S/c1-2-4-6-5-3-1;1-4(2)3/h1-5H;

| InChIKey = UDYFLDICVHJSOY-UHFFFAOYAG

| StdInChI_Ref = {{stdinchicite|correct|chemspider}}

| StdInChI = 1S/C5H5N.O3S/c1-2-4-6-5-3-1;1-4(2)3/h1-5H;

| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

| StdInChIKey = UDYFLDICVHJSOY-UHFFFAOYSA-N

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|Section2={{Chembox Properties

| Formula = C₅H₅NSO₃

| MolarMass = 159.16 g/mol

| Appearance = white solid

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|Section3={{Chembox Hazards

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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: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

:ROH + C₅H₅NSO₃ → [C₅H₅NH]⁺[ROSO₃]⁻

It also is useful for sulfamations:

:R₂NH + C₅H₅NSO₃ → C₅H₅N + R₂NSO₃H

The compound is used for sulfonylation reactions, especially in the sulfonylation of furans.{{Cite web|url=http://www.imperial.ac.uk/media/imperial-college/research-centres-and-groups/spivey-group/teaching/org2heteroaromatics/lecture451112.pdf|title=Heteroaromatic Chemistry Lectures 4 and 5|last=Spivey|first=Alan|date=12 March 2012|website=Imperial College Research|archive-url=|archive-date=|access-date=7 February 2017}} It is also an activating electrophile in a Parikh-Doering oxidation.{{cite journal | title = Sulfur trioxide in the oxidation of alcohols by dimethyl sulfoxide | author = Jekishan R. Parikh, William v. E. Doering |journal = J. Am. Chem. Soc. | year = 1967 | volume = 89 | pages = 5505–5507 | doi = 10.1021/ja00997a067 | issue = 21| bibcode = 1967JAChS..89.5505P }}