概述
Paracetamol (acetaminophen) is the most widely used analgesic and antipyretic drug globally, with annual production exceeding 145,000 tons. The industrial synthesis proceeds through reduction of p-nitrophenol to p-aminophenol, followed by acetylation with acetic anhydride. Modern catalytic hydrogenation methods have replaced older iron-acid reduction, improving yields and reducing waste. The drug is formulated into tablets, capsules, liquids, and suppositories for over-the-counter and prescription use.
化学工艺
p-Nitrophenol is catalytically hydrogenated to p-aminophenol using Pt/C or Pd/C catalyst at moderate pressure. The aminophenol is then acetylated with acetic anhydride in aqueous solution to form paracetamol, which is crystallized and dried.
HOC₆H₄NH₂ + (CH₃CO)₂O → HOC₆H₄NHCOCH₃ + CH₃COOH
原材料
-
p-Nitrophenol (C₆H₅NO₃) — Nitration of phenol (Starting material)
-
Hydrogen gas (H₂) — Steam methane reforming (Reducing agent)
-
Acetic anhydride ((CH₃CO)₂O) — Ketene process (Acetylating agent)
最终产品
-
Paracetamol (C₈H₉NO₂) — Analgesic and antipyretic (USP grade, >99% purity)
Environmental Impact
The catalytic hydrogenation route is significantly cleaner than the older iron-acid reduction, which generated large quantities of iron oxide sludge. Acetic acid byproduct is recovered and recycled. The process has moderate environmental impact with controlled wastewater treatment.
安全注意事项
- ⚠ p-Nitrophenol is toxic and environmentally persistent
- ⚠ Hydrogen gas is flammable and explosive
- ⚠ Platinum group metal catalysts require careful handling and recovery
- ⚠ Paracetamol dust is a potential inhalation hazard
最新创新
A new one-pot synthesis from hydroquinone using enzymatic amidation has been developed, eliminating the need for nitrophenol intermediates.
Continuous flow hydrogenation reactors improve safety and throughput.
生产规模
145000
吨/年
$680 million
市场价值