1337. Boric Anhydride

Nomenclature

CAS number: 1303-86-2
Boron oxide; boron trioxide; boric oxide; boron sesquioxide.
B2O3; mol wt 69.62.
B 31.06%, O 68.94%.

Description and references

Prepn of crystalline form: McCulloch, J. Am. Chem. Soc. 59, 2650 (1937). Review of toxicology and human exposure: Toxicological Profile for Boron (PB93-110674, 1992) 110 pp.

Properties

Colorless, brittle, vitreous, semitransparent, hygroscopic lumps or hard, white crystals. d (amorph) 1.8; d (cryst) 2.46. mp (cryst) 450°. Slowly sol in 30 parts cold, or 5 parts boiling water; sol in alcohol, glycerol. Keep dry.

Note

Has been improperly called anhydrous boric acid or fused boric acid.

Caution

Potential symptoms of overexposure are irritation of eyes, skin, respiratory system; cough; conjunctivitis; skin erythema. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 30.

Use

In metallurgy; in analysis of silicates to determine SiO2 and alkalies; in blowpipe analysis.