Orthoboric acid
Enhanced Solubility Characteristics: Demonstrates significant solubility in both aqueous and organic media, facilitating diverse implementation in purification protocols and recrystallization processes.
Structural Stability: Maintains molecular integrity as orthoboric acid, ensuring reliable performance in extended storage and varied industrial operations.
Controlled Acidity: Exhibits mild acidic properties in aqueous solutions, enabling effective function as a Lewis acid catalyst in multiple chemical transformations.
Thermal Transformation Behavior: Undergoes sequential dehydration at elevated temperatures, permitting controlled conversion to metaboric and pyroboric acid derivatives with modified reactivity profiles.
Boric acid is an inorganic crystalline compound formed through the hydration of boron trioxide. This substance exists primarily in three distinct molecular configurations: tetraboric acid (H₂B₄O₇, commonly termed pyroboric acid), polymeric metaboric acid (HBO₂)ₙ, and orthoboric acid (H₃BO₃). Among these structural forms, orthoboric acid represents the most hydrated and thermodynamically stable variant, exhibiting the highest degree of structural integrity.
Melting point | 160 °C (dec.) (lit.) |
Boiling point | 219-220 °C (9.7513 mmHg) |
density | 1.440 g/cm3 |
bulk density | 400-600kg/m3 |
vapor pressure | 2.6 mm Hg ( 20 °C) |
refractive index | n20/D 1.330-1.340 |
storage temp. | Store at +5°C to +30°C. |
solubility | H2O: soluble |
pka | 8.91±0.43(Predicted) |
form | working solution |
color | ≤10(APHA) |
Specific Gravity | 1.435 |
PH | 3.6-4.4 (25℃, saturated solution in H2O) |
Odor | Odorless |
PH Range | 3.8 - 4.8 |
Water Solubility | 49.5 g/L (20 ºC) |
Sensitive | Hygroscopic |
λmax | λ: 260 nm Amax: 0.05 |
Merck | 14,1336 |
BRN | 1697939 |
Exposure limits | ACGIH: TWA 2 mg/m3; STEL 6 mg/m3 |
InChIKey | KGBXLFKZBHKPEV-UHFFFAOYSA-N |
LogP | -1.09 at 22℃ |
CAS DataBase Reference | 10043-35-3(CAS DataBase Reference) |
NIST Chemistry Reference | B(OH)3(10043-35-3) |
EPA Substance Registry System | Orthoboric acid (10043-35-3) |
Absorption | ≤0.05 at 260 in H2O at 1M |
Safety Information
Hazard Codes | Xi,T,Xn |
Risk Statements | 36/37/38-60-63-62-61 |
Safety Statements | 26-36-53-45-37/39-36/37/39-22-24/25-23 |
WGK Germany | 2 |
RTECS | ED4550000 |
F | 3 |
TSCA | Yes |
HS Code | 28100090 |
Hazardous Substances Data | 10043-35-3(Hazardous Substances Data) |
Toxicity | LD50 orally in rats: 5.14 g/kg (Smyth). |
Orthoboric acid, conventionally referred to as boric acid, manifests as a white crystalline solid exhibiting either powdered or flaky morphology with a trigonal crystal structure and distinctive surface gloss. This odorless compound imparts a slightly bitter taste and conveys a soapy tactile sensation upon dermal contact. It demonstrates solubility in diverse media including aqueous solutions, ethanol, glycerol, ether solvents, and essential oils, yielding mildly acidic solutions. Thermal decomposition proceeds through sequential dehydration stages: metaboric acid generation occurs at 70–100°C, transformation to pyroboric acid at 150–160°C, and ultimate conversion to boron trioxide (B₂O₃) at 300°C. The substance presents toxicity concerns for human exposure. Aqueous solubility displays temperature-dependent characteristics: 2.77 g/100mL (0°C), 3.65 (10°C), 4.87 (20°C), 5.74 (25°C), 6.77 (30°C), 8.90 (40°C), 11.39 (50°C), 14.89 (60°C), 23.54 (80°C), and 38.00 (100°C). The acidic aqueous system functions as a classical Lewis acid, with solubility enhancement achievable through incorporation of hydrochloric acid, citric acid, or tartaric acid, thereby enabling purification via recrystallization techniques.
