Name | Selenic acid |
Synonyms | UN1905 HSDB 675 Selenic acid SELENIC ACID AR Selenocystathionine diammonium selenate dipotassium selenate Selenic acid (H2SeO4) selenic acid solution Selenic acid [UN1905] [Corrosive] 2-amino-4-(2-amino-3-hydroxy-3-oxopropyl)selanylbutanoic acid |
CAS | 7783-08-6 |
EINECS | 231-979-4 |
InChI | InChI=1/2H3N.H2O4Se/c;;1-5(2,3)4/h2*1H3;(H2,1,2,3,4) |
Molecular Formula | H2O4Se |
Molar Mass | 144.97 |
Density | 1.407g/mLat 25°C |
Melting Point | 58°C |
Boling Point | 260°C |
Flash Point | >230°F |
Water Solubility | g/100g H2O: 426 (0°C), 567 (20°C), 1328 (30°C) [LAN05]; decomposed by alcohol [HAW93] |
Solubility | Miscible with sulfuric acid. Immiscible with ammonia. |
Appearance | Liquid |
Color | Colorless |
Exposure Limit | ACGIH: TWA 0.2 mg/m3NIOSH: IDLH 1 mg/m3; TWA 0.2 mg/m3 |
Merck | 14,8429 |
pKa | 4.19±0.10(Predicted) |
PH | 2.74(1 mM solution);1.83(10 mM solution);0.97(100 mM solution) |
Stability | Stable, but decomposes on heating. Non-flammable. Incompatible with metals, combustible materials. Hygroscopic. |
Refractive Index | n20/D 1.5174(lit.) |
Use | Used as an analytical reagent and also for the preparation of selenium salts |
Risk Codes | R23/24/25 - Toxic by inhalation, in contact with skin and if swallowed. R34 - Causes burns R50/53 - Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment. R33 - Danger of cumulative effects R23/25 - Toxic by inhalation and if swallowed. R41 - Risk of serious damage to eyes R38 - Irritating to the skin |
Safety Description | S23 - Do not breathe vapour. S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S36/37/39 - Wear suitable protective clothing, gloves and eye/face protection. S45 - In case of accident or if you feel unwell, seek medical advice immediately (show the label whenever possible.) S61 - Avoid release to the environment. Refer to special instructions / safety data sheets. S60 - This material and its container must be disposed of as hazardous waste. S28 - After contact with skin, wash immediately with plenty of soap-suds. S20/21 - S16 - Keep away from sources of ignition. |
UN IDs | UN 3264 8/PG 1 |
WGK Germany | 2 |
RTECS | VS6575000 |
TSCA | Yes |
Hazard Class | 8 |
Packing Group | I |
EPA chemical substance information | information provided by: ofmpeb.epa.gov (external link) |
purpose | used as analytical reagent, also used in the preparation of selenium salt |
production method | 1. The sublimated selenium dioxide is added to an excess of hydrogen peroxide solution (30%), stirred evenly and then allowed to stand fully, then the mixture is heated to boiling and refluxed while oxygen is introduced, the oxidation reaction was completed. After completion of the reaction, the solution was distilled under vacuum, and the water and Unreacted hydrogen peroxide were distilled off. Near the end point, the vacuum degree was controlled to 533-667Pa, the temperature was increased to 150-160 oC, and the dry air was passed through the capillary, and the resulting product was a 99.8% selenic acid viscous liquid. Selenium acid can be obtained by oxidizing selenium dioxide with hydrogen peroxide. The synthesis reaction was carried out in a round-bottom flask with a reflux condenser tube, and a gas introduction tube was inserted near the bottom of the flask. 500mL G of SeO2 purified by sublimation was placed in the flask, and 30% of water was added to dissolve the solution, and of H2O2 was slowly added thereto. Oxygen was introduced from the gas inlet tube and the reaction mixture was heated to boiling for 12h. The aqueous solution of hydrogen sulfide can be used to test whether the oxidation is complete. If the red Se precipitate is not precipitated after adding hydrogen sulfide water to the test solution, the oxidation is complete. Otherwise, additional H2O2 should be added and oxygen boiling should be continued. The resulting solution was subjected to reduced-pressure distillation in a reduced-pressure distillation flask, and dry air was passed through a capillary tube during the distillation. The distilled off is essentially water and excess H2O2. When the temperature reached 150 deg C, the concentration of selenic acid up to 80% ~ 90%. If you want to continue to concentrate, can be in the 0.2 ~ 0.3kPa pressure distillation, but should pay attention to the temperature does not exceed 160 deg C, or selenium acid will be decomposed into selenous acid. The distillation was stopped when no more water droplets were condensed in the condenser and receiver. The resulting oily liquid was transferred to a crystallization dish and placed in a desiccator equipped with P4O10 to cool the crystals. To promote the formation of crystals, a small amount of selenic acid crystals may be added thereto as seed crystals. |
category | toxic substances |
toxicity grade | highly toxic |
Acute toxicity | Reference range: oral-rat LD50: 1.6 mg/kg; Intraperitoneal-rat LDL0: 8.973 mg/kg |
toxic substance data | information provided by: pubchem.ncbi.nlm.nih.gov (external link) |