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Selenium Trioxide

HCID 115128
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Basic information

CAS
13768-86-0
Standard SMILES
O=[Se](=O)=O
InChIKey
VFLXBUJKRRJAKY-UHFFFAOYSA-N
Molecular formula
O3Se
Average molar mass
126.97 g/mol
Monoisotopic mass
127.90127

Overview

Selenium trioxide is a white Solid. (USCG, 1999)

Names & identifiers

Preferred name
Selenium Trioxide
IUPAC
Trioxo-lambda~6~-selane
English name
Selenium trioxide
Molecular formula
O3Se
Molecular weight
126.96

Names & synonyms

Selenium trioxide13768-86-0Selenium oxide (SeO3)DTXSID50895004selenonylideneoxidaneselenic anhydrideTrioxide, SeleniumRefChem:182293DTXCID701324561237-385-1EINECS 237-385-1Trioxo-lambda~6~-selane
Show more names
Selenium(VI) oxideSelenium(VI) trioxideSelenium trioxide ISO 9001：2015 REACHSelenium oxide (SeO3) (6CI,7CI,8CI,9CI)
SCHEMBL268649VFLXBUJKRRJAKY-UHFFFAOYSA-NDB-371713Q6070

Database identifiers

CAS
13768-86-0
PubChem CID
115128
DTXSID
DTXSID50895004
EC Number
237-385-1
Nikkaji
J43.597J

Properties

Computed structural properties

Topological polar surface area
51.2 Ų
Hydrogen bond donors
0
Hydrogen bond acceptors
3
Rotatable bonds
0
Heavy atoms
4
Formal charge
0
Complexity
61.8

Experimental & physicochemical properties

Density · 2 items

3.6 at 68 °F (USCG, 1999) - Denser than water; will sink

3.6 g/cm³

SolubilitySolubility in water: very good
Decomposition180 °C
Melting Point · 2 items

244 °F (USCG, 1999)

118 °C

Physical Description · 2 items

Selenium trioxide is a white Solid. (USCG, 1999)

YELLOWISH-WHITE HYGROSCOPIC CRYSTALLINE POWDER.

Physicochemical properties

Melting point
118 °C · 118°C
Boiling point
180 ℃ · decomposes at 180℃ [CRC10]
Density
3.44 · 3.440
solubility
2 O, · soluble in H2O, organic solvents
form
white tetragonal crystals
color
white tetragonal crystals, crystalline; hygroscopic

Safety & regulation

Safety information is for reference only and does not replace the supplier’s Safety Data Sheet (SDS), applicable regulations, or professional assessment.

Hazard information

DOT LabelPoison
Fire Hazards · 2 items

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

Not combustible but enhances combustion of other substances. Many reactions may cause fire or explosion. Gives off irritating or toxic fumes (or gases) in a fire.

Health Hazards · 1 item

Absorption of selenium may be demonstrated by presence of the element in the urine and by a garlic-like odor of breath. Inhalation 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 or skin causes irritation. (USCG, 1999)

Reactive GroupOxidizing Agents, Strong
EC ClassificationSymbol: T, N; R: 23/25-33-50/53; S: (1/2)-20/21-28-45-60-61; Note: A
UN ClassificationUN Hazard Class: 6.1; UN Pack Group: II
Reactivity AlertsStrong Oxidizing Agent
Reactivity Profile · 1 item

Inorganic oxidizing agents, such as SELENIUM TRIOXIDE, can react with reducing agents to generate heat and products that may be gaseous (causing pressurization of closed containers). The products may themselves be capable of further reactions (such as combustion in the air). The chemical reduction of materials in this group can be rapid or even explosive, but often requires initiation (heat, spark, catalyst, addition of a solvent). Explosive mixtures of inorganic oxidizing agents with reducing agents often persist unchanged for long periods if initiation is prevented. Such systems are typically mixtures of solids, but may involve any combination of physical states. Some inorganic oxidizing agents are salts of metals that are soluble in water; dissolution dilutes but does not nullify the oxidizing power of such materials. Organic compounds in general have some reducing power and can in principle react with compounds in this class. Actual reactivity varies greatly with the identity of the organic compound. Inorganic oxidizing agents can react violently with active metals, cyanides, esters, and thiocyanates.

Chemistry & industry

Pharmacology

Metabolism/Metabolites · 1 item

Selenium may be absorbed through inhalation and ingestion, while some selenium compounds may also be absorbed dermally. Once in the body, selenium is distributed mainly to the liver and kidney. Selenium is an essential micronutrient and is a component of glutathione peroxidase, iodothyronine 5'-deiodinases, and thioredoxin reductase. Organic selenium is first metabolized into inorganic selenium. Inorganic selenium is reduced stepwise to the intermediate hydrogen selenide, which is either incorporated into selenoproteins after being transformed to selenophosphate and selenocysteinyl tRNA or excreted into the urine after being transformed into methylated metabolites of selenide. Elemental selenium is also methylated before excretion. Selenium is primarily eliminated in the urine and feces, but certain selenium compounds may also be exhaled. (L619)

Uses & manufacturing

UsesSelenium trioxide is used in the manufacture of photoelectric cells and solar energy devices. (L731)

Applications

General DescriptionWhite Solid.

Related reactions

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Compound notes

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Water Solubility
2 O · dissolves in H2O forming selenic acid [KIR82]
crystal system
square
Space group
421 c · P421c
Lattice constant
a/nm
RIDADR
3283 · 3283
HazardClass
6.1 · 6.1
PackingGroup
II
Chemical DangersDecomposes on heating. This produces toxic fumes. The solution in water is a strong acid. It reacts violently with bases and is corrosive. The substance is a strong oxidant. It reacts with combustible and reducing materials.
Packaging and LabellingDo not transport with food and feedstuffs.
Air and Water ReactionsReacts vigorously with water to form selenic acid solution.

Safety & protection

Fire Fighting · 2 items

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

In case of fire in the surroundings, use appropriate extinguishing media.

First Aid Measures · 4 items

Fresh air, rest. Half-upright position. Artificial respiration may be needed. Refer for medical attention.

First rinse with plenty of water for at least 15 minutes, then remove contaminated clothes and rinse again. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Do NOT induce vomiting. Refer for medical attention .

First AidINHALATION: remove victim to fresh air; give oxygen if necessary.
Safe StorageSeparated from combustible substances and food and feedstuffs. Dry. Keep in a well-ventilated room.
Nonfire Spill ResponseNeutralizing Agents for Acids and Caustics: Flush with water, rinse with dilute solution of sodium bicarbonate or soda ash. (USCG, 1999)
Spillage Disposal · 1 item

Evacuate danger area! Consult an expert! Personal protection: complete protective clothing including self-contained breathing apparatus. Do NOT let this chemical enter the environment. Sweep spilled substance into covered containers. Carefully collect remainder. Then store and dispose of according to local regulations. Do NOT absorb in saw-dust or other combustible absorbents.

Isolation and EvacuationExcerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:
Eye PreventionWear face shield or eye protection in combination with breathing protection.
Fire PreventionNO contact with combustible substances.
Inhalation RiskEvaporation at 20 °C is negligible; a harmful concentration of airborne particles can, however, be reached quickly , especially if powdered.
Skin PreventionProtective gloves. Protective clothing.
Minimum Risk LevelChronic Oral: 0.005 mg/kg/day (L134)

Toxicology

Health Effects · 1 item

Chronic oral exposure to high concentrations of selenium compounds can produce a disease called selenosis. The major signs of selenosis are hair loss, nail brittleness, and neurological abnormalities (such as numbness and other odd sensations in the extremities). Animal studies have shown that selenium may also affect sperm production and the female reproductive cycle. (L619)

Exposure Routes · 2 items

The substance can be absorbed into the body by inhalation of its aerosol and by ingestion.

Oral (L619) ; inhalation (L619) ; dermal (L619)

Toxicity Summary · 1 item

Selenium readily substitutes for sulfur in biomolecules and in many biochemical reactions, especially when the concentration of selenium is high and the concentration of sulfur is low. Inactivation of the sulfhydryl enzymes necessary for oxidative reactions in cellular respiration, through effects on mitochondrial and microsomal electron transport, might contribute to acute selenium toxicity. Selenomethionine (a common organic selenium compound) also appears to randomly substitute for methionine in protein synthesis. This substitution may affect the structure and functionability of the protein, for example, by altering disulfide bridges. Inorganic forms of selenium appear to react with tissue thiols by redox catalysis, resulting in formation of reactive oxygen species and causing damage by oxidative stress. (L619)

Signs and Symptoms · 5 items

Burning sensation. Cough. Laboured breathing. Sore throat. Shortness of breath. Symptoms may be delayed.

Redness. Pain. Blisters. Skin burns.

Redness. Pain. Severe deep burns.

Sore throat. Nausea. Abdominal pain. Burning sensation. Diarrhoea. Vomiting. Shock or collapse.

Short-term oral exposure to high concentrations of selenium may cause nausea, vomiting, and diarrhea. Brief exposures to high levels of elemental selenium or selenium dioxide in air can result in respiratory tract irritation, bronchitis, difficulty breathing, and stomach pains. Longer-term exposure to either of these air-borne forms can cause respiratory irritation, bronchial spasms, and coughing. (L619)

ICSC Environmental DataThe substance is harmful to aquatic organisms.
Carcinogen Classification3, not classifiable as to its carcinogenicity to humans. (L135)

Safety data

ridadr
3283
hazard_class
6.1
packing_group
II