Synthesis of tetracarbonyl dichlorodirhodium, RhCl3-3H2O+CORh2Cl2(CO)4+COCl2
Appropriate amount of rhodium(II) chloride trihydrate crystals was ground into a fine powder of 30-100 mesh with a mortar and pestle, and it was uniformly spread on a sand core in a glass reaction tube, and the length-to-diameter ratio of the said glass reaction tube was generally required to be 15, e.g., the length was 30 cm and the diameter was 2 cm; a gas source of carbon monoxide was connected to the said glass reaction tube, and then the lower part of the glass reaction tube was immersed into a heated oil source at room temperature for 5-10 minutes to drive out the residual air in the glass reaction tube. The glass reaction tube is connected to a carbon monoxide gas source, first ventilated at room temperature for 5-10 minutes to drive out the residual air in the glass reaction tube, and then the lower end of the glass reaction tube is immersed in a heated oil bath, and the liquid surface of the oil bath outside the glass reaction tube is higher than the reaction layer on said sand core; continuously ventilated with the carbon monoxide gas, the said rhodium(III) chloride trihydrate crystallized powder is gradually sublimated, and there are gradually orange-red needle-like crystals condensing on the inner pipe wall of said glass reaction tube (the mill plug in the upper port of the glass reaction tube can be opened at intervals of time (10-20 minutes) as required, and the water droplets on the inner pipe wall of the glass reaction tube can be sucked dry with absorbent cotton); when the reaction is finished, there should be almost no reactant residue on the said sand core, and at this time the carbon monoxide gas source can be shut off and the glass reaction tube can be taken out from the oil bath, and the mill plug can be opened, and the water drops on the inner pipe wall of the glass reaction tube can be sucked up with the scraping spoon. The orange-red needle-like crystals on the wall of the glass reaction tube can be scraped off and collected, and the tetracarbonyldichlorodirhodium can be obtained, and its melting point is 124.
