Dimethyl cyclohex-2-ene-1,4-dicarboxylate → Dimethyl terephthalate

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Reaction Conditions

Reaction Steps

In a Parr pressure reactor, dimethyl cyclohex-2-ene-1,4-dicarboxylate (2.42 g, 12.2 mmol) is dissolved in cyclohexane (120 ml, 0.10 M) and a catalytic amount of platinum on carbon (476 mg, 5 percent Pt/C, 1 mole percent platinum) powder is added. The reactor is pressurized with air (240 psi (1.65 MPa) at 23° C. after saturation of the solution) and its contents are heated at a 150° C. set-point temperature for 3 days under rapid stirring (160 rpm). After opening the cooled Parr reactor, a suspension of black platinum on carbon (Pt/C) in a near colorless solution is present. All solvent is removed from a sample of the suspension, and the entire residue is dissolved in CDCl3 for 1H NMR analysis. Integration of the respective resonances shows the presence of about 23 percent unreacted dimethyl cyclohex-2-ene-1,4-dicarboxylate starting material, of about 59 percent dimethyl terephthalate oxidation product, and of about 18 percent dimethyl cyclohexane-1,4-dicarboxylate disproportionation by-product. Column chromatography (Si35, SF40-150 g, AnaLogix column with 10 percent ethyl acetate/hexane isocratic eluent) provides pure dimethyl terephthalate.

Provenance & Evidence