Shandong Huashang Chemical Co., Ltd. is a high-tech enterprise specializing in the research and development, manufacturing, and sales of fine chemicals. Headquartered in Jinan, Shandong, China, we are committed to delivering high-quality products to our global partners. Currently, over 90% of our products are exported to developed markets, including North America, Europe, Japan, South Korea, and the Middle East.
Product Description
Sulfur Trioxide (CAS: 14265-45-3), also known as sulfuric anhydride, is a highly reactive inorganic oxide with strong oxidizing and corrosive properties. It exists in three allotropic forms: two are solids at room temperature, while the third is an oily liquid. As a key intermediate in the industrial production of sulfuric acid, it is widely used as a sulfonating agent in organic synthesis, as well as in the manufacture of chlorosulfonic acid, synthetic detergents, and cation exchange resins. It fumes strongly in air due to rapid absorption of moisture, and its violent reaction with water makes it a hazardous material requiring strict handling.
Molecular Formula & Structure
Molecular Formula: SO?
Physical Properties
- Appearance: Colorless to white crystalline solid or oily liquid (depending on allotropic form); fumes in air
- Melting Point: Not fixed (mixture of allotropes); varying based on the specific allotrope
- Density: Approximately g/cm3 (room temperature)
- Boiling Point: Moderate; sublimes easily at room temperature
- Solubility: Reacts violently with water to form sulfuric acid; soluble in concentrated sulfuric acid to form oleum; insoluble in non-polar organic solvents
- Stability: Stable under dry conditions; prone to polymerization without inhibitors; decomposes when exposed to moisture
- Vapor Pressure: Moderate at room temperature (for the oily allotrope)
Chemical Properties
- CAS Number: 14265-45-3 (confirmed); EINECS: 237-186-5; PubChem ID: 1118
- Chemical Type: Inorganic oxide, strong oxidant, sulfonating agent, corrosive substance
- Molecular Weight: Approximately 80
- Chemical Characteristics: Strong Lewis acid; reacts violently with water, oxygen difluoride, tetrafluoroethylene, and perchloric acid; has strong oxidizing properties, capable of oxidizing metals and halides at high temperatures
- Reactivity: Undergoes sulfonation reactions with organic compounds, often requiring dilution to control reaction intensity
- Application Type: Intermediate for sulfuric acid production; sulfonating agent for organic synthesis; raw material for chlorosulfonic acid, synthetic detergents, and cation exchange resins
- Toxicity: Highly toxic by inhalation and ingestion; causes severe corrosion and burns to skin, eyes, and mucous membranes; toxic to aquatic organisms and harmful to the environment
Synthesis Method
- Raw Materials: Sulfur dioxide, oxygen, vanadium pentoxide (catalyst); alternatively, sodium bisulfate or pyrosulfuric acid (for laboratory synthesis)
- Synthesis Route: Industrial production via the contact process (oxidation of sulfur dioxide with oxygen over vanadium pentoxide catalyst); laboratory synthesis via pyrolysis of sodium bisulfate or distillation of oleum
- Reaction Steps: Industrial process: Purify and dry sulfur dioxide gas, mix with oxygen, and react at high temperature over vanadium pentoxide catalyst (supported on kieselguhr or silica) to produce sulfur trioxide, with a high conversion rate via two-stage absorption; Laboratory process: Heat sodium bisulfate to form sodium pyrosulfate, then further heat to decompose into sulfur trioxide and sodium sulfate
Storage & Safety
- Storage: Store in a sealed, dry, and well-ventilated area; recommended storage temperature within a moderate range (solid or liquid); keep away from moisture, water, organic materials, and strong reducing agents; add inhibitors to prevent polymerization
- Package: Corrosion-resistant, airtight containers (various sizes); UN number: 1829; packing group I; hazard class 8
- Safety: Operate in a well-ventilated fume hood; wear full PPE (acid-resistant gloves, protective clothing, face shield, gas mask); avoid skin, eye contact, and inhalation of fumes; do not use water to extinguish fires involving sulfur trioxide
- Hazard: Corrosive and highly reactive; reacts violently with water to release large amounts of heat; ignites organic materials on contact; thermal decomposition emits toxic fumes; toxic to aquatic organisms and causes environmental pollution
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