boron trisulfide is a yellow to white crystal or amorphous powder that turns paste upon heating. It is soluble in sulfur dichloride, phosphorus trichloride, and alcohols but not in water or at room temperature. It reacts with iron boroide to form boric acid.
Corrosive to eyes, skin and respiratory tract. May cause lung edema when inhaled. Exposure to vapors may discolor and erode teeth, ulcerate nasal and oral mucosa and cause nose and gum bleeding. It can also cause choking and coughing, dyspnea, chest pain and bronchitis. Inhalation may also cause fluorosis of bones and teeth. Short-term inhalation exposures up to 6 months at 12.8 ppm/m3 caused fluorosis of bones and teeth and other soft tissues in guinea pigs.
Long-term inhalation exposures at concentrations of 3.1-4 ppm/m3 resulted in dental and skeletal fluorosis in rats. Long-term inhalation exposures up to 3-4 ppm/m3 can lead to nasal and ocular irritation, choking, sneezing, and difficulty breathing. The fluorine content in rat teeth and bones was elevated at these levels but not in the lung, liver and blood.
A process for preparing substantially pure boron trisulfide comprises fluidizing a mixture of solid calcium boride, carbon or iron boride with an inert gas to fluidize the bed, reacting the fluidized bed with hydrogen sulfide and recovering the boron trisulfide evolved. The crude product is purified by sublimation at 250 C. The invented process is an improvement over existing processes for preparing boron trisulfide because it allows the desired compound to be produced in large amounts at a reasonable cost.