1,4-Cyclohexanedimethanol: Dimethyl Terephthalate Hydrogenated over Palladium, then Copper Chromite

1,4-Cyclohexanedimethanol (CHDM) is the glycol that goes into PETG and other polyesters. Eastman's two-stage process (Akin, Lewis and Reid, US 3,334,149, 1967) hydrogenates molten dimethyl terephthalate at about 5500 psi: first over palladium, then over copper chromite; the inventors explain that the first saturates the ring and the second turns the ester groups into alcohols. Either catalyst alone makes almost no CHDM. The patent's example converted 97 % of the ester. The picture: Fig. 1 of the patent.