Boric Acid
(Boracic Acid; Orthoboric Acid). CAS: 10043-35-3.
H.BOS.
Properties: Colorless, odorless scales or white powder; stable in air. D: 1.4347 (15C), mp inde terminate since it loses water in stages through metaboric acid, HBO2, pyroboric acid, Hâ‚‚BO and to the oxide B2O3. Soluble in boiling water, alcohol, and glycerol. Noncombustible.
Derivation:
(a) By adding hydrochloric or sulfuric acid to a solution of borax and crystallizing.
(b) From weak borax brines by extraction with kerosene solution of a chelating agent such 2-ethyl-1,3-hexanediol or other polyols. Borates are stripped from the chelate by sulfuric acid. a as
Method of Purification: Recrystallization.
Hazard: Toxic via ingestion.
Use only weak solutions.
Irritant to skin in dry form.
Grade:
Technical, 99.9%, CP, USP.
Use: Heat-resistant (borosilicate) glass, glass fi- bers, porcelain enamels, boron chemicals, metal- lurgy (welding flux, brazing copper), flame retar- dant in cellulosic insulation, mattress batting and cotton textile products, fungus control on citrus fruits (FDA tolerance 8 ppm boron residue), ointment and eye wash (water solution only), nickel electroplating baths.