Isoprenaline hydrochloride
[CAS 51-30-9]

Identification

• Classification: API >> Respiratory medication >> Asthma
• Name: Isoprenaline hydrochloride
• Synonyms: 3,4-Dihydroxy-alpha-((isopropylamino)methyl)-benzyl alcohol hydrochloride; 4-(1-Hydroxy-2-((methylethyl)amino)ethyl)-1,2-benzenediol hydrochloride; Aludrine hydrochloride
• Molecular Formula: C₁₁H₁₇NO₃.HCl;C₁₁H₁₈ClNO₃
• Molecular Weight: 247.72
• CAS Registry Number: 51-30-9
• EC Number: 200-089-8
• SMILES: CC(C)NCC(C1=CC(=C(C=C1)O)O)O.Cl

Properties

• Melting point: 165 - 175 °C (Decomposes) (Expl.)
• Solubility: DMSO 50 mg/mL, Water 50 mg/mL (Expl.)

Safety Data

• Hazard Symbols: GHS07 Warning
• Risk Statements: H315-H319-H335
• Safety Statements: P261-P264-P264+P265-P271-P280-P302+P352-P304+P340-P305+P351+P338-P319-P321-P332+P317-P337+P317-P362+P364-P403+P233-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Specific target organ toxicity - single exposure	STOT SE	3	H335
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Eye irritation	Eye Irrit.	2A	H319

chemBlink Chemical Story

Isoprenaline hydrochloride, also called isoproterenol hydrochloride, is the salt of a landmark synthetic catecholamine agonist. Historical reviews place isoproterenol's introduction around 1940 and describe it as an important early step toward pharmacologically selective bronchodilation. Unlike epinephrine, it has little alpha-adrenergic agonism and strongly stimulates beta receptors, but it is not beta2-selective: beta1 cardiac stimulation accompanies beta2 bronchodilation. It became both a medicine and an experimental tool that helped establish alpha/beta adrenoceptor pharmacology. Later beta2-selective agonists reduced cardiac stimulation and largely displaced it from routine asthma treatment.

The exact registry identity matters because related free forms, salts, hydrates, stereoisomers, process intermediates and finished medicines can have separate CAS numbers even when their names share a familiar stem. In pharmaceutical and fine-chemical work this distinction is practical: composition changes formula weight and can alter solubility, crystallization, analytical standards, manufacturing specifications and interpretation of physical-property data.

The molecule also illustrates how chemists use functional groups as deliberate handles. Aromatic rings and heterocycles establish shape and electronic character, while amines, alcohols, carbonyl groups, carboxylic acids, esters or ionic centers control reactivity and intermolecular interactions. In a multistep route, an intermediate may be valuable precisely because one group can be transformed selectively while another survives for a later operation.

Modern development is equally an analytical problem. Chemists must demonstrate identity and purity, control stereochemistry or salt composition where relevant, follow process-related impurities and establish reproducible specifications. Reference materials and isolated intermediates therefore have scientific importance even when they are never administered to a patient or sold as the final commercial product.

A careful Chemical Story must distinguish documented use from structural possibility. A familiar scaffold can suggest a biological hypothesis, but resemblance is not evidence that the exact CAS substance has been tested, approved or commercially adopted for that purpose. The account therefore emphasizes verified identity, development history and supported applications, and deliberately leaves unsupported claims out.

Seen more broadly, the compound shows that useful molecular design rarely depends on one functional group in isolation. Performance emerges from the whole structure, stereochemistry and physical form, the route used to make it, and the environment in which it operates. Connecting those molecular details to a real manufacturing, analytical or therapeutic role turns a technical registry entry into a meaningful chemical story.

The exact registry identity matters because related free forms, salts, hydrates, stereoisomers, process intermediates and finished medicines can have separate CAS numbers even when their names share a familiar stem. In pharmaceutical and fine-chemical work this distinction is practical: composition changes formula weight and can alter solubility, crystallization, analytical standards, manufacturing specifications and interpretation of physical-property data.

The molecule also illustrates how chemists use functional groups as deliberate handles. Aromatic rings and heterocycles establish shape and electronic character, while amines, alcohols, carbonyl groups, carboxylic acids, esters or ionic centers control reactivity and intermolecular interactions. In a multistep route, an intermediate may be valuable precisely because one group can be transformed selectively while another survives for a later operation.

Modern development is equally an analytical problem. Chemists must demonstrate identity and purity, control stereochemistry or salt composition where relevant, follow process-related impurities and establish reproducible specifications. Reference materials and isolated intermediates therefore have scientific importance even when they are never administered to a patient or sold as the final commercial product.

References:
1. PubChem. Isoproterenol Hydrochloride.
2. Historical reviews of beta-adrenoceptor agonist development.
3. Reviews of adrenergic receptor pharmacology.

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