(CH3)3NH][Rh2I7] As a catalyst for the conversion of carbon monoxide and carbonylation of methanol

Abstract

Rhodium compounds are catalysts for several reactions involving carbon monoxide (1,2). In the present work, they report the synthesis of a catalytically active rhodium complex prepared by the reaction of a solution of ((CH/sub 3/)/sub 3/NH)/sub 3/(RhCl/sub 6/) x 3H/sub 2/O (I) in DMF acidified with hydrochloric acid, with analytical-grade (45.1%) hydriodic acid upon heating. They used 2 g (I), 100 ml DMF, 5 ml hydrochloric acid, and 25 ml hydriodic acid. These components were heated at 80-100/sup 0/C for 30 min. The complex product was isolated as a black powder, washed on a filter with ethanol and ether, and dried at 20/sup 0/C (0.1 mm) for 3 h. The yield was 90%. The IR spectral and elemental analysis data indicate that this complex is ((CH/sub 3/)/sub 3/NH)(Rh/sub 2/I/sub 7/) (II). Found: Rh 17.7; C 3.4; H 1.3; N 1.5; I 76.0%. Calculated for Rh/sub 2/C/sub 3/H/sub 10/Ni/sub 7/: Rh17.84; C 3.12; H 0.86; N 1.21; I 76.97% IR spectrum (nu, cm/sup -1/): 800 (CN), 1010 (Rh), 1450 (CH/sub 3/), 1595 (NH), 3085 (NH). Complex (II) decomposes without melting above 300/sup 0/C, is nonhygroscopic, and is soluble in DMF. The catalytic properties of (II) are comparable with those of othermore » rhodium compounds. Thus, the activity of (II) in the conversion of CO with water is 2.8 mole H/sub 2//g-atom Rh x h (46 mg (II), 13 ml AcOH, 6 ml HCl, 6 ml H/sub 2/O, 8.4 g NaI, 600 mm, 90/sup 0/C). The conversion was 51% in the carbonylation of methanol in acetic acid using 17.8 mg (II), 20 ml HI, 9.3 ml CH/sub 3/CH/sub 2/COOH, and 0.4 ml methanol at 185/sup 0/C, 30 atm for 2 h.« less