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38078-09-0 - Diethylaminosulfur trifluoride, 95% - DAST - A11992 - Alfa Aesar

A11992 Diethylaminosulfur trifluoride, 95%

CAS Number

Size Price ($) Quantity Availability
5g 80.34
25g 257.50
100g 630.36
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Diethylaminosulfur trifluoride, 95%


Chemical Properties

Formula Weight
Boiling Point
Flash Point
Refractive Index
Moisture Sensitive
Miscible with water, ethanol, benzene and acetonitrile.


Diethylaminosulfur trifluoride (DAST) is used as a precursor to prepare 2,6-dimethoxybenzoyl fluoride and 2-thiazolines. It is a useful fluorinating agent used for a variety of compounds including alcohols, thioethers, alkenols and cyanohydrins. It also serves as a catalyst for Friedel-Crafts allylation reaction using tertiary cyclopropyl silyl ethers and in the rearrangement of homoallylic alcohols to unsaturated aldehydes. It plays an important role for gem difluorination of ketopipecolinic acids.


Store in cool place. Moisture sensitive. It reacts with water and ethanol. Incompatible with water, acids and bases.

Literature References

Reagent for conversion of alcohols to alkyl fluorides and carbonyl compounds to gem-difluorides, less prone to cause dehydration or rearrangement than SF4: J. Org. Chem., 40, 574 (1975); Org. Synth. Coll., 6, 835 (1988); Eur. J. Org. Chem., 3177 (2000); Tetrahedron Lett, 44, 6661 (2003); reviews: Org. React., 35, 513 (1988); Austral. J. Chem., 54, 75 (2001); Synlett, 1130 (2006). Conversion of alcohols to fluorides has been accomplished with stereocontrol at the chiral center: Tetrahedron: Asym., 4, 161 (1993).

Use of dichloromethane as solvent permits the selective monofluorination of sugars: J. Org. Chem., 48, 393 (1983). Glycosyl fluorides, which are useful building blocks for oligosaccharides: J. Am. Chem. Soc., 105, 2430 (1983), and C-glycosides, can be prepared by reaction of DAST with phenylthioglycosides: J. Am. Chem. Soc., 106, 4189 (1984). The reaction with diols can lead to difluorides, sulfite esters or cyclic ethers: J. Chem. Soc., Perkin 2, 861 (1995).

Convenient reagent for conversion, in the absence of base, of N-protected amino acids to the acyl fluorides: Lett. Pept. Sci., 2, 285 (1996); Indian J. Chem., 39, 384 (2000); compare Cyanuric fluoride, A15666. Review of peptide coupling via amino acid halides: Acc. Chem. Res., 29, 268 (1996). See also Appendix 6.

In the presence of SbCl3, promotes the fluoro-Pummerer rearrangement of sulfoxides: J. Am. Chem. Soc., 107, 735 (1985); Org. Synth. Coll., 9, 446 (1998):

Direct conversion of thioethers to the ɑ-fluoro analogues has also been reported: J. Org. Chem., 58, 3800 (1993). Fluorination of thioesters leads to ɑɑ-difluoroethers: J. Org. Chem., 55, 768 (1990):

See also 4-Morpholinyl­sulfur trifluoride, L19751.

Gao, X.; Tang, X. Effective reduction of graphene oxide thin films by a fluorinating agent: Diethylaminosulfur trifluoride. Carbon 2014, 76, 133-140.

Anxionnat, B.; Robert, B.; George, P.; Ricci, G.; Perrin, M. A.; Pardo, D. G.; Cossy, J. Correction to Ring Expansion of Cyclic beta-Amino Alcohols Induced by Diethylaminosulfur Trifluoride: Synthesis of Cyclic Amines with a Tertiary Fluoride at C3. J. Org. Chem. 2014, 77 (14), 6087-6099.

GHS Hazard and Precautionary Statements

Hazard Statements: H331-H314-H318-H226

Toxic if inhaled. Causes severe skin burns and eye damage. Causes serious eye damage. Flammable liquid and vapour.

Precautionary Statements: P280-P303+P361+P353-P305+P351+P338-P310-P402

Wear protective gloves/protective clothing/eye protection/face protection. IF ON SKIN (or hair): Remove/Take off immediately all contaminated clothing. Rinse skin with water/shower. IF IN EYES: Rinse cautiously with water for several minutes. Remove contact lenses, if present and easy to do. Continue rinsing. Immediately call a POISON CENTER or doctor/physician. Store in a dry place.

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