6-(1-Pyrrolidinyl)-2,4-pyrimidinediamine 3-oxide
[CAS# 55921-65-8]

Identification

• Classification: Pharmaceutical intermediate >> Heterocyclic compound intermediate >> Pyrimidine compound >> Aminopyrimidine
• Name: 6-(1-Pyrrolidinyl)-2,4-pyrimidinediamine 3-oxide
• Synonyms: 2,4-Diamino-6-pyrrolidinopyrimidine 3-oxide
• Molecular Formula: C₈H₁₃N₅O
• Molecular Weight: 195.22
• CAS Registry Number: 55921-65-8
• EC Number: 611-333-1
• SMILES: C1CCN(C1)C2=NC(=N)N(C(=C2)N)O

Properties

• Solubility: 1.152e+005 mg/L (25 °C water)
• Density: 1.6±0.1 g/cm³, Calc.^*
• Index of Refraction: 1.759, Calc.^*
• Melting point: 158.28 °C
• Boiling Point: 549.3±60.0 °C (760 mmHg), Calc.^*, 383.73 °C
• Flash Point: 286.0±32.9 °C, Calc.^*

^* Calculated using Advanced Chemistry Development (ACD/Labs) Software.

Safety Data

• Hazard Symbols: GHS05 Danger
• Risk Statements: H314
• Safety Statements: P280-P305+P351+P338-P310

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	4	H302

Discovery and Applications

6-(1-pyrrolidinyl)-2,4-pyrimidinediamine 3-oxide, also known as pyrilamine, was first synthesized and characterized in the mid-20th century by pharmaceutical researchers looking for new antihistamine compounds. Its discovery stems from the development of drugs that can reduce allergic reactions and related symptoms by targeting histamine receptors in the body. Pyrilamine belongs to the ethylenediamine class of antihistamines and has potent antagonistic activity against histamine, a key mediator of allergic reactions.

Pyrilamine is primarily used as an antihistamine to treat a variety of allergic diseases, including allergic rhinitis, allergic conjunctivitis, urticaria, and atopic dermatitis. It works by blocking the effects of histamine on H1 receptors, thereby reducing symptoms such as sneezing, itching, nasal congestion, runny nose, watery eyes, and rashes. Pyrilamine is often included in over-the-counter cold and flu medications, especially those designed to relieve symptoms such as stuffy nose, sneezing, and runny nose. Its antihistamine properties help relieve nasal and respiratory symptoms associated with the common cold, flu, and upper respiratory tract infections, temporarily relieving congestion and discomfort. Pyrilamine is a key ingredient in allergy relief preparations, including oral tablets, capsules, and liquid suspensions, as well as nasal sprays and eye drops. Pyrilamine may be incorporated into topical preparations such as creams, lotions, and gels for the treatment of allergic skin conditions, including atopic dermatitis, eczema, and insect bites. Its antihistamine and anti-inflammatory properties help reduce itching, redness and swelling associated with allergic skin reactions, soothing symptoms and promoting healing. Pyrilamine is used in veterinary medicine to treat allergic diseases in companion animals, including dogs, cats, and horses, to relieve symptoms such as itching, scratching, and skin irritation caused by environmental allergens, insect bites, and food allergies.

References

2018. The Chemical and Products Database, a resource for exposure-relevant data on chemicals in consumer products. Scientific Data, 5.
DOI: 10.1038/sdata.2018.125