Rhodium(III) Chloride

Description

Rhodium trichloride is a red-brown or black,odorless solid or liquid. Molecular weight = 209.26; 263.32(trihydrate); Boiling point = 775℃ (sublimes); Freezing/Melting point = 400-500℃(decomposition). HazardIdentification (based on NFPA-704 M Rating System):Health 3, Flammability 0, Reactivity 1. Insoluble in water.Rhodium trichloride trihydrate, RhCl3 - xH2O, is a deep-redcrystalline solid. Soluble in water.

Chemical Properties

Rhodium(III) Chloride, also known as rhodium trichloride, is a red-brown or black crystalline powder that is easily deliquescent. poisonous! Molecular weight 209.26 (anhydrous), melting point 450～500°C (decomposition). Boiling point 800°C (sublimation). To 600°C above to generate polyfluoride. It can be reduced by hydrogen at 70°C. Insoluble in water, acid, aqua regia, soluble in methanol and cyanide solution. In concentrated acid (nitric acid, sulfuric acid) heating decomposition. When heated, it can interact with metals such as sodium, aluminum, magnesium, and iron.

Physical properties

Brownish-red powder; deliquescent; decomposes on heating at 450 to 500°C; sublimes at 800°C; insoluble in water, water-solubility, however, depends on the method of preparation; soluble in alkali hydroxide or cyanide solutions; soluble in aqua regia
The trihydrate is a dark red powder; deliquescent; loses water at 100°C; very soluble in water; soluble in alcohol and hydrochloric acid; insoluble in ether.

Uses

Rhodium(III) Chloride is used in homogeneous catalysis, for example in the industrial prodcution of acetic acid. It is used to coat optic fibres and optical mirrors, and for crucibles, thermocouple elements and headlight reflectors. manufacture of rhodium trifluoride.

Preparation

Rhodium trichloride is prepared by heating rhodium with chlorine gas at 250°C:
2Rh + 3Cl₂ → 2RhCl₃
Also, the chloride salt may be obtained by treating the yellow hydrous oxide, Rh₂O₃.5H₂O, with hydrochloric acid. The solution is carefully evaporated to form a dark red and water-soluble salt, rhodium trichloride tetrahydrate, RhCl₃.4H₂O. Heating the tetrahydrate in a stream of hydrogen chloride gas at 180°C forms the anhydrous salt, RhCl₃.

Application

Rhodium(III) chloride precursor may be used to dope graphene with Rh nanoparticles to prepare hybrids for electrocatalysis in energy, sensing and biomedical sectors. It can be used to prepare [Rh(NH3)6]Cl3.

Reactions

Catalyst in conjunction with "pybox" for the asymmetric hydrosilylation of ketones.
C-C bond forming reactions.

Hazard

Toxic by ingestion.

Safety Profile

Poison by ingestion, intraperitoneal, and intravenous routes. Experimental reproductive effects. Questionable carcinogen with experimental carcinogenic data. Mutation data reported. Incompatible with pentacarbonyl iron + zinc. When heated to decomposition it emits toxic fumes of Cl-. See also RHODIUM and CHLORIDES

Potential Exposure

Rhodium trichloride is used in hydrosilylation, hydrogenation, carbonylation, oxidation, arylation. See also “Rhodium Metal.” In plating operations and in catalyst preparation, the metal will be used as the trichloride.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seekmedical attention immediately. If this chemical contactsthe skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove fromexposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing hasstopped and CPR if heart action has stopped. Transferpromptly to a medical facility. When this chemical hasbeen swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.

storage

Color Code—White: Corrosive or ContactHazard; Store separately in a corrosion-resistant location.Prior to working with this chemical you should be trainedon its proper handling and storage. Store in tightly closedcontainers in a cool, well-ventilated area away from strongoxidizers. Where possible, automatically transfer materialfrom drums or other storage containers to processcontainers.

Shipping

UN3260 Corrosive solid, acidic, inorganic, n.o.s., Hazard class: 8; Labels: 8-Corrosive material, Technical Name Required.

Purification Methods

Probable impurities are KCl and HCl. Wash the chloride well with small volumes of H2O to remove excess KCl and KOH and dissolve it in the minimum volume of conc HCl. Evaporate it to dryness on a steam bath to give wine-red coloured RhCl3.3H2O. Leave it on the steam bath until the odour of HCl is lost-do not try to dry further as it begins to decompose above 100o to the oxide and HCl. It is not soluble in H2O but soluble in alkalis or CN solutions and forms double salts with alkali chlorides. [Anderson & Basolo Inorg Synth VII 214 1963.]

Incompatibilities

Sensitive to humidity. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materi- als, strong bases, strong acids, oxoacids, and epoxides.

Waste Disposal

Recovery and reclaiming wherever possible in view of high economic value. See “Rhodium Metal.”