Trifluoroacetic acid → Citronellal

Participants

Reaction Steps

In a 3-L reaction flask were added 500.0 g (3.28 mol) of citral, 2.50 g (0.5 wt % based on the citral) of 5 wt. % Pd/barium sulfate, 10.0 g (22.9 mmol, 2.0 wt % based on the citral) of (2R,4R)-2-(bis-(4′-t-butylphenyl)methyl)-4-(ethylcarbamoyloxy)pyrrolidine, 2.6 g (22.9 mmol) of trifluoroacetic acid, and 500 mL of 10 wt % hydrous t-butanol in a nitrogen atmosphere. The resulting mixture was stirred and the atmosphere was exchanged with a hydrogen atmosphere (0.1 MPa (atmospheric pressure)). After stirring at 60° C. for 21 hours, the catalyst was filtered off and the residue was analyzed using gas chromatography. As a result, it was found that a conversion ratio from citral to citronellal was 99.4% and an optical purity was 90.9% e.e. The crude-citronellal thus obtained was distilled to obtain 398 g (2.58 mol, yield: 78.6%) of d-citronellal having a purity of 98%.

Provenance & Evidence