Phenylacetylcarbinol

Phenylacetylcarbinol (abbreviated PAC) is an organic compound used as a chemical precursor in the synthesis of pharmaceuticals such as pseudoephedrine. A chiral molecule, generally only the laevo diastereomer of phenylacetylcarbinol (abbreviated variously as L-PAC, R-PAC, LPAC, or (R)-PAC) is used, because L-PAC transforms to (R)-(-)-pseudoephedrine—the commercially used isomer of pseudoephedrine—when processed in a reductive amination reaction.

Production
L-PAC is widely synthesized by fermentation of benzaldehyde and dextrose. In this process, colonies of yeast (in particular, strains such as Candida utilis, Torulaspora delbrueckii, or Saccharomyces cerevisiae) are cultivated and added to a broth of water, dextrose, and the enzyme pyruvate decarboxylase in a vat. The yeast is left to grow for a period of time, after which the benzaldehyde is introduced into the broth. The yeast then ferments the benzaldehyde into L-PAC.

The majority of L-PAC is generated in pharmaceutical plants in India, as an intermediate precursor in the production of pseudoephedrine.