Leflunomide

Also known as: Arava, HWA 486, SU101, 5-Methyl-N-[4-(trifluoromethyl)phenyl]isoxazole-4-carboxamide, N-(4-Trifluoromethylphenyl)-5-methylisoxazole-4-carboxamide

Leflunomide (CAS 75706-12-6) is a compound in the Organohalogen Compounds category listed in the Jingsj chemical database. It has the molecular formula C12H9F3N2O2 and a molecular weight of 270.207 g/mol. Key properties include a melting point of 163-168°C, a boiling point of 289.3±40.0 °C at 760 mmHg, a density of 1.4±0.1 g/cm3 and a flash point of 128.8±27.3 °C. It is classified under GHS with signal word Danger and hazard statements H301 — Toxic if swallowed, H315 — Causes skin irritation and H319 — Causes serious eye irritation. No supplier offers are currently listed; request a quote. Record last updated Aug 21, 2026.

CAS No.: 75706-12-6
Jingsj CID: J-35297-6
Molecular Formula: C₁₂H₉F₃N₂O₂
Molecular Weight: 270.207 g/mol
Category: Organohalogen Compounds
Last updated: 8/21/2026

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Physicochemical Properties

Melting Point	163-168°C
Boiling Point	289.3±40.0 °C at 760 mmHg
Density	1.4±0.1 g/cm3
Flash Point	128.8±27.3 °C
Exact Mass	270.061615
PSA	55.13000
LogP	1.95
Vapor Pressure	0.0±0.6 mmHg at 25°C
Refractive Index	1.541

GHS Safety & Compliance

Acute ToxicitySignal word: Danger

H301 — Toxic if swallowed
H315 — Causes skin irritation
H319 — Causes serious eye irritation
H335 — May cause respiratory irritation

Activity & Biological Data

Additional Information	[1]. Davis JP, et al. The immunosuppressive metabolite of leflunomide is a potent inhibitor of human dihydroorotate dehydrogenase. Biochemistry. 1996 Jan 30;35(4):1270-3. [2]. Xu X, et al. Inhibition of protein tyrosine phosphorylation in T cells by a novel immunosuppressive agent, leflunomide. J Biol Chem. 1995 May 26;270(21):12398-403. [3]. Fox RI, et al. Mechanism of action for leflunomide in rheumatoid arthritis. Clin Immunol. 1999 Dec;93(3):198-208.

Additional Information

[1]. Davis JP, et al. The immunosuppressive metabolite of leflunomide is a potent inhibitor of human dihydroorotate dehydrogenase. Biochemistry. 1996 Jan 30;35(4):1270-3. [2]. Xu X, et al. Inhibition of protein tyrosine phosphorylation in T cells by a novel immunosuppressive agent, leflunomide. J Biol Chem. 1995 May 26;270(21):12398-403. [3]. Fox RI, et al. Mechanism of action for leflunomide in rheumatoid arthritis. Clin Immunol. 1999 Dec;93(3):198-208.

Customs & Trade Information

HS Code	2934999090
Summary	2934999090. other heterocyclic compounds. VAT:17.0%. Tax rebate rate:13.0%. . MFN tariff:6.5%. General tariff:20.0%

Frequently Asked Questions

What is the CAS number of Leflunomide?

The CAS number of Leflunomide is 75706-12-6.

What are the molecular formula and molecular weight of Leflunomide?

Leflunomide has molecular formula C12H9F3N2O2 and molecular weight 270.207 g/mol.

Is Leflunomide hazardous?

Leflunomide has GHS signal word Danger and hazard statements H301 — Toxic if swallowed; H315 — Causes skin irritation; H319 — Causes serious eye irritation.

What are the upstream and downstream products of Leflunomide?

For Leflunomide, Upstream Products: 5-methyl-4-isoxazolecarbonyl chloride, 4-(Trifluoromethyl)aniline, 5-Methylisoxazole-4-carboxylic acid.

Data compiled from public chemical databases such as PubChem and supplier catalogs; supplier offers are provided by suppliers.

Last updated: 8/21/2026

How to cite: Jingsj. "Leflunomide (CAS 75706-12-6)". Jingsj Chemical Database. https://www.jingsj.com/compound/J-35297-6 (accessed 2026-11-07).

Data for reference only; verify product details with suppliers before purchase.