Copper(II) trifluoromethanesulfonate is the copper(II) salt of trifluoromethanesulfonic acid abbreviated Cu(OTf)2, it is a powerful Lewis acid. It is used as a catalyst in several organic reactions, such as the Diels–Alder reaction and cyclopropanation reactions.

Property

Copper(II) trifluoromethanesulfonate is a white powder, commercially available. Blue powder when freshly prepared.

Solubility: sol MeOH, EtOH, DMF, MeCN, and formamide; also sol i-PrCN and acetone.

Uses

Copper(II) trifluoromethanesulfonate is mostly used as a catalyst for:

Mannich condensation

Annulative amination

Friedel-Crafts reaction

Henry reaction

Hypervalent iodine reagent-mediated preparation of carbazoles

Intramolecular oxidative C-N bond formation for the synthesis of carbazoles

Catalyzes the efficient addition of trimethylsilyl cyanide to carbonyl compounds.

Preparation

The most conveniently prepared from copper(II) carbonate and triflic acid (Trifluoromethanesulfonic Acid) in MeCN.The freshly prepared salt precipitated from Et2O is pale blue.

Storage and Precautions

Copper(II) trifluoromethanesulfonate is moisture sensitive; can be handled in air for quick transfers; pure samples are only mildly corrosive. Appears to be indefinitely stable in the absence of air, moisture, and light.