ST 91

Also known as: 2-(2,6-Diethylphenylamino)-2-imidazoline hydrochloride, 2-Imidazoline, 2-(2,6-diethylanilino)-, hydrochloride, 2-[(2,6-Diethylphenyl)imino]imidazolidine, N-(2,6-Diethylphenyl)-4,5-dihydro-1H-imidazol-2-amine hydrochloride, N-(2,6-Diethylphenyl)imidazolidine-2-imine, N-(2,6-diethylphenyl)-4,5-dihydro-1H-imidazol-3-ium-2-amine chloride, ST-91, St 91-Cl

ST 91 (CAS 4749-61-5) is a compound in the Organic Compounds category listed in the Jingsj chemical database. It has the molecular formula C13H20ClN3 and a molecular weight of 253.77100 g/mol. It is also known as 2-(2,6-Diethylphenylamino)-2-imidazoline hydrochloride, 2-Imidazoline, 2-(2,6-diethylanilino)-, hydrochloride and 2-[(2,6-Diethylphenyl)imino]imidazolidine. Key properties include a boiling point of 325.1ºC at 760 mmHg and a flash point of 150.4ºC. No supplier offers are currently listed; request a quote. Record last updated Aug 21, 2026.

CAS No.: 4749-61-5
Jingsj CID: J-1106302-3
Molecular Formula: C₁₃H₂₀ClN₃
Molecular Weight: 253.77100 g/mol
Category: Organic Compounds
Last updated: 8/21/2026

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Physicochemical Properties

Boiling Point	325.1ºC at 760 mmHg
Flash Point	150.4ºC
Exact Mass	253.13500
PSA	36.42000
LogP	2.82190
Storage Conditions	-20°C

Activity & Biological Data

Target	α2-adrenergic receptor
Additional Information	[1]. Graham BA, et, al. Synergistic interactions between two alpha(2)-adrenoceptor agonists, dexmedetomidine and ST-91, in two substrains of Sprague-Dawley rats. Pain. 2000 Mar;85(1-2):135-43. [2]. Maccari S, et, al. α-Adrenoceptor stimulation attenuates melanoma growth in mice. Br J Pharmacol. 2022 Apr;179(7):1371-1383. [3]. Stone LS, et, al. ST91 [2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride]-mediated spinal antinociception and synergy with opioids persists in the absence of functional alpha-2A- or alpha-2C-adrenergic receptors. J Pharmacol Exp Ther. 2007 Dec;323(3):899-906.

Target

α2-adrenergic receptor

Additional Information

[1]. Graham BA, et, al. Synergistic interactions between two alpha(2)-adrenoceptor agonists, dexmedetomidine and ST-91, in two substrains of Sprague-Dawley rats. Pain. 2000 Mar;85(1-2):135-43. [2]. Maccari S, et, al. α-Adrenoceptor stimulation attenuates melanoma growth in mice. Br J Pharmacol. 2022 Apr;179(7):1371-1383. [3]. Stone LS, et, al. ST91 [2-(2,6-diethylphenylamino)-2-imidazoline hydrochloride]-mediated spinal antinociception and synergy with opioids persists in the absence of functional alpha-2A- or alpha-2C-adrenergic receptors. J Pharmacol Exp Ther. 2007 Dec;323(3):899-906.

Frequently Asked Questions

What is the CAS number of ST 91?

The CAS number of ST 91 is 4749-61-5.

What are the molecular formula and molecular weight of ST 91?

ST 91 has molecular formula C13H20ClN3 and molecular weight 253.77100 g/mol.

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

Last updated: 8/21/2026

How to cite: Jingsj. "ST 91 (CAS 4749-61-5)". Jingsj Chemical Database. https://www.jingsj.com/compound/J-1106302-3 (accessed 2026-10-28).

Data for reference only; verify specifications, grades and regulatory status with suppliers before purchase.