Name | Rhodium iodide |
Synonyms | RHI3 Rhodium iodide RHODIUM IODIDE RHODIUM TRIIODIDE RHODIUM(LLL)IODIDE rhodiumiodide(rhi3) RHODIUM(III) IODIDE rhodium(3+) triiodide |
CAS | 15492-38-3 |
EINECS | 239-521-5 |
InChI | InChI=1/3HI.Rh/h3*1H;/q;;;+3/p-3/rI3Rh/c1-4(2)3 |
Molecular Formula | I3Rh |
Molar Mass | 483.62 |
Density | 6.400 |
Water Solubility | Insoluble in water. |
Appearance | Black crystalline powder |
Color | Black |
Exposure Limit | ACGIH: TWA 0.01 mg/m3; TWA 1 mg/m3NIOSH: IDLH 2 mg/m3; IDLH 100 mg/m3; TWA 0.001 mg/m3; TWA 0.1 mg/m3 |
Storage Condition | Keep in dark place,Inert atmosphere,Room temperature |
Stability | hygroscopic |
Sensitive | Hygroscopic |
MDL | MFCD00016311 |
Physical and Chemical Properties | Black solid, MONOCLINIC CRYSTAL, similar to AlCl3 Crystal, density of 665g/cm3, stable at normal temperature and pressure, at 675 ° C. Began to decompose. Hygroscopic. Soluble in alcohol, water and acetone. |
Safety Description | 24/25 - Avoid contact with skin and eyes. |
RTECS | VI9315000 |
TSCA | Yes |
HS Code | 28439000 |
EPA chemical information | Information provided by: ofmpub.epa.gov (external link) |
use | rhodium triiodide (RhI3) is a black crystal powder with Rh content of 19.5 ~ 21.3%, which is easy to deliquesce in the air. As a catalyst for carbonylation synthesis reaction, it is widely used in the synthesis of acetic acid, acetic anhydride, ethylene glycol and other reactions. As the main catalyst for carbonyl synthesis, especially as a catalyst for the synthesis of acetic anhydride. (2015-12-21) |
Preparation | CN201010153085.9 discloses a method for preparing a carbonylated rhodium iodide solution. A method for preparing carbonylated rhodium iodide solution is carried out according to the following steps:(1) dehydration and carbonylation: solid rhodium triiodide and anhydrous acetic acid are put into an autoclave, after carbon monoxide is introduced, stirring is started, the temperature is raised to 80-140 ℃, the pressure of the autoclave is adjusted to 0.5-1.0MPa, and stirring is continued for 0-4h under this condition;(2) Dissolution: pump water into the reactor with a pump, after continuous stirring for 20-60min, a carbonylated rhodium iodide solution with a rhodium concentration higher than 2000ppm was obtained. According to the method of the present invention, a carbonylated rhodium iodide solution with a rhodium concentration of 2000-5000ppm can be obtained in a short time. |
Overview | Rhodium iodide, black crystal, is relatively stable at room temperature and pressure, and begins to decompose at 675 ℃; the current common synthesis methods mainly include solution synthesis Method and direct synthesis method; it is often used as the main catalyst for carbonyl synthesis, especially as a catalyst for the synthesis of acetic anhydride. |
preparation method | 1. direct synthesis method uses the ability of iodine to form iodine free radical under the action of initiator, so that rhodium powder and iodine powder directly react to generate rhodium iodide. the reaction is as follows: 2Rh +3I2=2RhI3 operation method: rhodium powder, iodine powder and initiator (preferably isopropyl benzene peroxide, dosage 0.3%) are added to the reactor in proportion and sealed, put the mixture into a muffle furnace, raise the temperature to the specified temperature and maintain it for a certain period of time, so that rhodium and iodine can fully react, remove the black product after cooling, heat to 90°C and keep the temperature for a period of time until constant weight, and use acetic acid after cooling Dissolve the rhodium iodide generated after the reaction, and evaporate the acetic acid under reduced pressure to obtain a black rhodium iodide solid. 2. Solution synthesis method: dissolve rhodium trichloride in water, add appropriate amount of potassium iodide or hydroiodic acid, keep it at a certain temperature for 3 hours, filter, wash with a small amount of water for 3 times, and dry to obtain black crystals. RhCl3+ 3KI / HI = RhI3↓ + 3KCl/ HCl3. In the new synthesis method, 2g of rhodium powder and 100mL of composite solvent R101 (composed of inorganic acids and initiators) are added to the reaction kettle, heated slowly, kept refluxing for 2h when the temperature in the kettle rises to the required value, transferred to the rotary evaporator after the metal is completely dissolved, and the solvent is evaporated for recycling. Add potassium iodide to the remaining small amount of liquid, react at a constant temperature of 80 ℃ for 0.5h, and obtain black solid powder rhodium iodide after cooling crystallization, filtration, washing and drying. |
quality specification | rhodium (Rh) content: ≥ 21.3% iron (Fe) content: ≤ 0.005% nitrate (NO3-1), content: ≤ 0.005% |
Production method | The reaction of metal rhodium powder and I2 at 400 ℃ can generate crystalline rhodium iodide. If KI solution is added to RhCl3 solution, amorphous RhI3 precipitate is generated. |