1. catechol (120.033 g, 1.09 mol) and K2CO3 (316 g, 2.29 mol) were co-milled at 28°C and 18% humidity to obtain a homogeneous mixture which was transferred to a 500 mL beaker.
2. The beaker was placed in an autoclave and purged three times with CO2 (600 psi) and then charged with CO2 to 860 psi.
3. the reactor was placed in an oil bath and gradually heated to 225°C over 3 hours, at which time the pressure in the kettle was increased to 1170 psi.
4. the pressure was reduced to 380 psi (250°C) over a period of 1.25 hours and the reaction was subsequently maintained at 230°C for 15 hours.
5. Upon completion of the reaction, the kettle was cooled to room temperature (160 psi) and placed in a refrigerator for opening.
6. The kettle was opened and the reaction mixture (which appeared as a hard gray solid with turquoise and white flecks) was mixed with 1.5 L of water and 1 L of concentrated hydrochloric acid.
7. Slowly bubble the mixture to produce a beige foam for 3 hours, then break up the solid mass with a glass rod and stir with a magnetic stirring bar for 2 hours.
8. Filter the beige slurry and dry the solids under vacuum at room temperature for 14 hours.
9. the light gray solid was washed with 4L of Millipore water and subsequently dried under vacuum at room temperature for 9 days.
10. The dried gray solid was ground into powder and further dried on a vacuum line for 26 hours (95%).
11. The product was characterized by 1H NMR (400 MHz, MeOD, δ: 7.34, s, Ar H, 2H), 13C NMR (101 MHz, MeOD, δ: 117.8, 120.1, 152.6, 173.2), and HRMS-ESI (m/z: [M-H]- calculated value 197.0092, measured value 197.0094). ) were performed for characterization.
