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Selenium dioxide

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Products Intro: Product Name:Selenium dioxide
CAS:7446-08-4
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Products Intro: Product Name:SeleniuM(IV) oxide, 99.4% (Metals basis)
CAS:7446-08-4
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Products Intro: Product Name:SeleniuM dioxide
CAS:7446-08-4
Purity:99% Package:10g--1kg--5kg--25kg--3000kg
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Purity:>98% .NMR+LCMS Package:50Mg/100Mg/500Mg/1g/5g/10g/
Selenium dioxide Basic information
Physical Properties Preparation Reactions Toxicity
Product Name:Selenium dioxide
Synonyms:SeleniuM dioxide >=99.9% trace Metals basis;SeleniuM dioxide reagent grade, powder, 98%;NSC 56753;Selenium dioxide 99.999% trace metals basis;Selenium dioxide ReagentPlus(R), powder, 99.8% trace metals basis;BLUE DUO PROTEIN MARKER,HIGH RANGE;Selenium(IV) oxide, 99% trace metals basis;Selenium(IV) oxide, 99.999% trace metals basis
CAS:7446-08-4
MF:O2Se
MW:110.96
EINECS:231-194-7
Product Categories:metal oxide;Inorganics;Metal and Ceramic Science;Oxides;Selenium;Others;Oxidation;Synthetic Reagents
Mol File:7446-08-4.mol
Selenium dioxide Structure
Selenium dioxide Chemical Properties
Melting point 315 °C (subl.)(lit.)
Boiling point 684.9 °C(lit.)
density 4.81 g/mL at 25 °C(lit.)
vapor pressure 1 mm Hg ( 157 °C)
refractive index nD20 <1.76
Fp 315°C
storage temp. Store below +30°C.
solubility H2O: soluble
form powder
color white
PH2 (10g/l, H2O, 20℃)
Water Solubility 38.4 g/100 mL (14 ºC)
Sublimation 315 ºC
Merck 14,8434
Stability:Stable. Incompatible with organic materials, strong acids, ammonia, nitric acid, halogen acids. Protect from moisture.
CAS DataBase Reference7446-08-4(CAS DataBase Reference)
NIST Chemistry ReferenceSelenium dioxide(7446-08-4)
EPA Substance Registry SystemSelenium oxide (SeO2)(7446-08-4)
Safety Information
Hazard Codes T,N,Xn
Risk Statements 36/38-50/53-33-23/25-51/53-20/22
Safety Statements 26-61-60-45-28A-20/21-28
RIDADR UN 3440 6.1/PG 3
WGK Germany 2
RTECS VS8575000
3
TSCA Yes
HS Code 2811 29 90
HazardClass 6.1
PackingGroup II
Hazardous Substances Data7446-08-4(Hazardous Substances Data)
ToxicityLD50 orally in Rabbit: 68.1 mg/kg
MSDS Information
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Selenium dioxide Usage And Synthesis
Physical PropertiesWhite tetragonal crystals; acidic taste; leaves a burning sensation; density 3.95 g/cm3; sublimes at 315°C forming greenish yellow vapors with a sour and pungent odor; melts at 340 to 350°C; vapor pressure 12.5 torr at 70°C; soluble in water, 38.4 g/100mL at 14°C; highly soluble in hot water 82.5 g/100mL at 65°C; soluble in benzene; moderately soluble in ethanol and acetone 6.7 and 4.4g/100mL solvent, respectively, at 15°C; sparingly soluble in acetic acid (1.11g/100mL at 14°C).
PreparationSelenium dioxide is obtained by burning selenium metal in oxygen:
Se + O2 → SeO2
Selenium also forms a trioxide, SeO3. In excess oxygen the product mixture may contain both dioxide and trioxide. The trioxide is unstable.
Selenium dioxide may be prepared by heating selenium with oxygen and nitrogen dioxide. Presence of excess oxygen would oxidize nitrogen dioxide to pentoxide, instead converting selenium dioxide to trioxide:
2Se + 3O2 + 4NO2 → 2SeO2 + 2N2O5
Selenium dioxide also may be produced by oxidation of selenium by nitric acid. The overall reaction may be written as follows:
Se + 2HNO3 → SeO2 + H2O + NO2 + NO
ReactionsSelenium dioxide is reduced to selenium metal when heated with carbon and other reducing agents.
When heated with ammonia, selenium dioxide forms selenium, nitrogen and water:
3SeO2 + NH3 → 3Se + 2N2 + 6H2O
Ammonia reacts with selenium dissolved in ethanol to form ammonium ethyl selenite, NH4(C2H5)SeO3.
Reaction with nitric acid forms selenic acid:
Se + 2HNO3 → H2SeO4 + 2NO
Selenium dioxide is reduced by hydrazine to black amorphous selenium:
SeO2 + N2H4 → Se + N2 + 2H2O
Hydroxylamine hydrochloride reduces selenium dioxide to reddish-brown amorphous selenium:
SeO2 + 4NH2OH•HCl → Se + 2N2 + 6H2O + 4HCl
The dioxide rapidly absorbs hydrogen halides, forming selenium oxyhalides:
SeO2 + HBr → SeOBr2 + H2O
Reaction with thionyl chloride yields selenium oxychloride:
SeO2 + SOCl2 → SeOCl2 + SO2
ToxicityThe compound is toxic by ingestion. Symptoms of the poisoning effects of selenium dioxide are similar to those of selenium metal. Selenium dioxide vapors are highly irritating to eyes, nose and respiratory tract.
Chemical PropertiesYellowish white to reddish powder or crystals. It is soluble in water and hygroscopic and absorbs moisture or water from the air. Selenium oxide is incompatible with strong oxidising agents, reducing agents, strong acids, ammonia, organics, and phosphorus trichloride.
Chemical PropertiesSelenium dioxide is white to slightly reddish crystalline solid or yellow liquid which forms a yellowgreen vapor. It has a sour and pungent odor. Odor threshold in air50.0002 milligram per cubic meter.
UsesIn the manufacture of other selenium compounds; as a reagent for alkaloids; as oxidizing agent: L. F. Fieser, M. Fieser, Reagents for Organic Chemistry vol. 1 (New York, Wiley, 1967) p 992.
General DescriptionA white or creamy-white volatile lustrous crystal or crystalline powder with a pungent sour smell. Melting point 340 deg C. Density 3.954 g / cm3 . Toxic by ingestion and inhalation.
Air & Water ReactionsIn presence of water will corrode most metals [USCG, 1999]. Readily soluble in water forming selenious (selenous) acid.
Reactivity ProfileInorganic oxidizing agents, such as Selenium dioxide , react with reducing agents to generate heat and products that may be flammable, combustible, or otherwise reactive. Selenium dioxide reacts with water, particularly hot water, to give selenious (selenous) acid, a weak acid that is corrosive. Stable to light and heat. Rapidly absorbs dry hydrogen fluoride, hydrogen chloride, hydrogen bromide to form the corresponding selenium oxohalide. A good oxidizing agent. Reacts oxidatively with ammonia to form dinitrogen gas and selenium [Merck]. Oxidizes many organic substances.
HazardToxic by inhalation, ingestion, and skin absorption.
Health HazardAbsorption of selenium may be demonstrated by presence of the element in the urine and by a garlic-like odor of the breath. Inhalation of dust can cause bronchial spasms, symptoms of asphyxiation, and pneumonitis. Acute symptoms of ingestion include sternal pain, cough, nausea, pallor, coated tongue, gastrointestinal disorders, nervousness, and conjunctivitis. Contact with eyes causes irritation.
Fire HazardSpecial Hazards of Combustion Products: Sublimes and forms toxic vapors when heated in fire.
Potential ExposureSelenium dioxide is used in the manufacture of selenium compounds, a reagent for alkaloids; an oxidizing agent; in paint and ink pigments; in metal “blueing” and etching; as a chemical catalyst; in photographic toners; in electric and photoelectric components; and others.
First aidMove victim to fresh air. Call 911 or emergency medical service. Give artificial respiration if victim is not breathing. Do not use mouth-to-mouth method if victim ingested or inhaled the substance; give artificial respiration with the aid of a pocket mask equipped with a one-way valve or other proper respiratory medical device. Administer oxygen if breathing is difficult. Remove and isolate contaminated clothing and shoes. In case of contact with substance, immediately flush skin or eyes with running water for at least 20 minutes. For minor skin contact, avoid spreading material on unaffected skin. Keep victim warm and quiet. Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed. Ensure that medical personnel are aware of the material(s) involved and take precautions to protect themselves. Medical observation is recommended for 24 to 48 hours after breathing overexposure, as pulmonary edema may be delayed. As first aid for pulmonary edema, a doctor or authorized paramedic may consider administering a drug or other inhalation therapy.
ShippingUN3283Selenium compound, solid, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous material, Technical Name Required.
Purification MethodsPurify it by sublimation at 315o, or by solution in HNO3, precipitation of selenium which, after standing for several hours or boiling, is filtered off, then re-oxidised by HNO3 and cautiously evaporated to dryness below 200o. The dioxide is dissolved in H2O and again evaporated to dryness. In H2O it forms selenious acid (see selenious acid above). Its solubility in H2O is 70%w/w at 20o, and it is soluble in EtOH. [Waitkins & Clark Chem Rev 36 235 1945, Fehér in Handbook of Preparative Inorganic Chemistry (Ed Brauer) Academic Press Vol I p 421 1963.]
IncompatibilitiesSelenium dioxide is and inorganic oxidizer; reacts, possibly violently, with reducing agents such as hydrides, nitrides, alkali metals, and sulfides. Contact with strong acids may cause release of toxic hydrogen selenide gas. Water solution is a medium-strong acid (selenious acid). Rapidly absorbs dry hydrogen fluoride, hydrogen bromide, hydrogen chloride, to form corresponding selenium oxohalides. Reacts with many substances producing toxic selenium vapors. Attacks many metals in presence of water.
Waste DisposalConsult with environmental regulatory agencies for guidance on acceptable disposal practices. Generators of waste containing this contaminant (≥100 kg/mo) must conform to EPA regulations governing storage, transportation, treatment, and waste disposal.
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