A series of heterogenized rhodium complex catalysts for the carbnylation of methanol have been synthesized by the reaction of tetracarbonyldichloro - dirhodium with linear and cross - linked copolymers. These complexes were high catalytic in carbonylation of methanol to acetic acid and acetic anhydride. The active centers of these catalysts consist of (a) a cis - dicarbonyl rhodium moiety coordinated with the borderline base pyridine N and adjacent oxygen to form N→Rh and O→Rh coordination bond

respectively

and (b) the said moiety coordinated with two adjacent pyridine N's to form two N→Rh bonds. The former plays a more active role than the latter in catalysts. These catalysts are thermally stable. With methyl iodide as promoter

methanol in acetic acid could be carbonylated to acetic acid and acetic anhydrine simultaneously as final products with a turnover rate at 10

4

moles methanol converted/(mol Rh • h

-1

).