Phosphorus trichloride

Phosphorus trichloride can generate hydrochloric acid mist in the air. It has a corrosive and irritating effect on the skin and mucous membranes. Short-term inhalation of large amounts of vapor can cause irritation of the upper respiratory tract, leading to pharyngitis and bronchitis. In severe cases, laryngeal edema may occur, resulting in suffocation, pneumonia, or pulmonary edema. Skin and eye contact can cause irritation or burns. Severe eye burns may lead to blindness. Chronic effects: Long-term low-concentration exposure can cause irritation of the eyes and respiratory tract. It may also cause phosphorus-induced oral disease.

Basic Information

Chinese Name: Phosphorus Trichloride

English Name: phosphorus trichloride

Other Names: Phosphorus(III) Chloride

Chemical Formula: PCl3

Molecular Weight: 137.33

CAS Registry Number: 7719-12-2

EINECS Registry Number: 231-749-3

Melting Point: -93.6 °C (179.6 K)

Boiling Point: 76.1 °C (349.3 K)

Water Solubility: Reacts with water

Flash Point: None

Applications: Used in the pesticide, pharmaceutical, and dye industries; serves as a catalyst, solvent for phosphorus, and chlorinating agent.

Properties

Colorless clear liquid. Soluble in water and ethanol, decomposing with the release of heat. Soluble in benzene and carbon disulfide. Relative density (d²¹⁴) 1.574. Melting point -112°C. Boiling point 76°C. Low toxicity, LD50 (rat, oral) 550 mg/kg. Corrosive.

Storage

Store sealed in a cool, dry place.

Uses

Catalyst. Solvent for phosphorus. Chlorinating agent.

Safety Measures

Seal packaging, store away from light, and avoid moisture. Separate storage from alkalis, oxidizers, and metal powders. Ensure personal protection; avoid direct body contact. In case of skin (eye) contact, rinse with flowing water.

Chemical Properties

Exposed to humid air, it hydrolyzes to form phosphorous acid and hydrogen chloride. The chemical equation is PCl3 + 2H2O = HPO2 + 3HCl, further forming the complex acid H3PCl6, producing white fumes and deteriorating. Must be stored sealed. Reacts with ethanol and water through hydrolysis. Reacts with oxygen to form phosphorus oxychloride.

Phosphorus trichloride is a colorless clear fuming liquid with a relative density of 1.574 g/cm³ (21°C), melting point -112°C, boiling point 75.5°C, and vapor pressure 13.33 kPa (21°C). Soluble in benzene, carbon disulfide, and carbon tetrachloride. Exposed to air, it absorbs moisture and hydrolyzes, forming phosphorous acid and hydrogen chloride, producing white fumes and deteriorating. Reacts with oxygen to form phosphorus oxychloride and with chlorine to form phosphorus pentachloride. Contact with organic materials may cause fire. Flammable. Easily irritates mucous membranes, corrosive, and toxic.