Boron Trichloride

Boron Trichloride (BCl₃, CAS 10294-34-5) is a colorless, pungent gas that liquifies easily (bp 12.5 °C). It hydrolyzes violently with moisture and must be handled under strictly anhydrous conditions. As a strong Lewis acid, it is a critical specialty gas for semiconductor processes, including plasma dry etching and boron doping. It also serves as a refining agent for Al/Mg/Zn/Cu alloys and a precursor for high-purity boron and BN. Available in industrial grade (≥99.0%) and electronic grades up to 99.9995%. Classified as toxic and corrosive (UN 1741, Class 2.3+8, PG I); store below 10 °C, isolated from water, alkalis, and alcohols.

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Product Introduction

Zouping Jinxing Chemical Co., Ltd. is one of the leading manufacturers and suppliers of boron trichloride in China. If you're going to wholesale bulk boron trichloride made in China, welcome to get free sample from our factory. All customized products are with high quality and low price.

Basic physical properties

Appearance: Boron trichloride is a colorless, fuming liquid (stored under pressure at room temperature); in its gaseous state, it is colorless and has a strong, pungent, acidic odor.
Melting point: −107°C
Boiling point: 12.6°C (at atmospheric pressure; highly volatile)
Density: 1.35 g/cm³ (liquid, 20°C)
Vapor pressure: Approx. 133 kPa (approx. 1.3 atm) at 20°C
Solubility: Hydrolyzes violently upon contact with water; soluble in organic solvents such as benzene, dichloromethane, and carbon tetrachloride.
Molecular structure: Planar triangular; sp² hybridization; the boron (B) atom is electron-deficient and readily accepts lone pair electrons.

Key chemical reaction characteristics

1. Violent hydrolysis upon contact with water (the most hazardous reaction)
BCl₃ + 3H₂O → B(OH)₃ + 3HCl↑
The hydrolysis is exothermic and releases large amounts of hydrogen chloride gas, which forms a white acidic mist in the air. This accounts for its "fuming" nature and necessitates strictly anhydrous conditions for all operations.
2. Strong Lewis acidity
It can form stable adducts with compounds containing lone-pair electrons, such as ammonia, amines, ethers, alcohols, and esters; for example:
BCl₃ + (C₂H₅)₂O → Cl₃B·O(C₂H₅)₂
This property makes it an excellent dealkylation reagent in organic synthesis (particularly for demethylation and debenzylation).
3. Halogen exchange reaction
It reacts with fluorides at high temperatures to produce boron trifluoride (BF₃); this is one of the key industrial methods for producing BF₃.

Major industrial applications

Semiconductors and Microelectronics (Primary Application Area)
Chemical Vapor Deposition (CVD): As a boron source, boron trichloride is used to prepare boron-doped silicon thin films and high-performance ceramic coatings such as titanium diboride (TiB₂) and boron nitride (BN).
Ion Implantation: High-purity BCl₃ is used for p-type doping in semiconductor devices.
Dry Etching: Used for etching metal interconnects (e.g., aluminum, copper); offers high selectivity and rapid etching rates.
Organic Synthesis and Pharmaceuticals
Catalyst: Acts as a catalyst for Friedel-Crafts acylation and alkylation reactions; it is milder than AlCl₃ and allows for easier post-reaction processing (the hydrolysis product, boric acid, is easily removed).
Deprotecting Agent: Specifically used to remove methyl ether protecting groups (–OCH₃) from aromatic rings; operates under mild conditions without affecting other sensitive functional groups.
Pharmaceutical Intermediates: Used in the synthesis of boron-containing drugs such as Bortezomib (anticancer) and Apixaban (anticoagulant).
Fine Chemicals
Used to prepare specialty materials such as borate esters, boron-nitrogen compounds, and boron fibers.
Acts as a chlorinating agent to convert metal oxides into chlorides (e.g., producing TiCl₄ from ilmenite).

FAQ

Q: Toxicity and Occupational Health

A: Acute LD₅₀/LC₅₀: Rat inhalation LC₅₀ (4h) 1270.5 mL/m³ (highly toxic class);

Primary hazards: Highly corrosive + pulmonary edema (delayed onset):

Inhalation causes laryngospasm, bronchial edema, chemical pneumonia, and delayed pulmonary edema (symptoms appear only after several hours; aggravated by physical exertion);

Skin contact: Severe chemical burns + frostbite from liquid contact (rapid vaporization absorbs heat);

Eye contact: Severe deep burns, loss of vision;

Fatal at high concentrations.

Chronic: Neurotoxic; long-term exposure causes liver and kidney damage, tooth erosion and discoloration, and nasal ulceration.

Carcinogenicity: Not listed as a carcinogen by IARC, NTP, or OSHA.

No standard Chinese PC-TWA value established; strictly controlled by analogy to "highly toxic gas + corrosive substance" categories.

Q: Key Points for Handling and Storage

A: Fully sealed stainless steel piping + pressure reducing valve + flashback arrestor + dual-alarm system for HCl/toxic gases; open-vessel operations are prohibited.

Store gas cylinders upright and secured in a cool, dry, ventilated, and explosion-proof area (≤30°C), keeping them away from water, alkalis, alcohols, amines, oxidizing agents, and food products (minimum safety distance of 50m).

Purge the system with dry inert gas (N₂/He) before introducing BCl₃; perform the same purge upon shutdown to prevent moisture backflow.

PPE: Handling leaks requires Level A gas-tight chemical protective suits and SCBA; routine inspections require full-face respirators, acid-resistant gloves, and safety goggles. Handling with bare hands is strictly prohibited.

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