Benzenesulfonamide, 5-[(2,4-diamino-5-pyrimidinyl)oxy]-2-methoxy-4-(1-methylethyl)-, 2-hydroxy-1,2,3-propanetricarboxylate (1:1)

China [CN]

I. Basic Information

Item | Details

English Full Name | Benzenesulfonamide, 5-[(2,4-diamino-5-pyrimidinyl)oxy]-2-methoxy-4-(1-methylethyl)-, 2-hydroxy-1,2,3-propanetricarboxylate (1:1)

Chinese Name | 5-[(2,4-diamino-5-pyrimidinyl)oxy]-2-methoxy-4-(1-methylethyl)benzenesulfonamide citrate (1:1)

CAS No. | 100040-45-3 (free base); Citrate salt does not have a separate CAS number and is usually associated with the free base CAS number.

Molecular Formula | Free base C₁₃H₁₈N₆O₄S; Citrate salt C₁₃H₁₈N₆O₄S・C₆H₈O₇

Molecular Weight | Free base 354.38; Citrate salt 552.50

Chemical Synonyms | 4-isopropyl-2-methoxy-5-[(2,4-diaminopyrimidin-5-yl)oxy]benzenesulfonamide citrate

Mechanism of Action | Dihydrofolate reductase (DHFR) inhibitor, blocks DNA synthesis by inhibiting folate metabolism, exerting antibacterial/antitumor activity.

Research and Development Use | Intermediate for antibacterial and antitumor drugs, used in the development of drugs for sensitive bacterial infections and cancer treatment.

II. Physicochemical Properties

Parameter | Data

Appearance | White to off-white crystalline powder

Melting Point | 182–186°C (decomposition)

Solubility | The citrate salt has better water solubility than the free base, approximately 50–100 mg/mL (pH 7.0), slightly soluble in ethanol, and practically insoluble in diethyl ether and chloroform.

Dissociation Constant (pKa) | Free base pKa≈7.8 (sulfonamide group), 5.2 (amino group); Citric acid pKa₁=3.13, pKa₂=4.76, pKa₃=6.40

Stability | 25°C/60% Stable for 6 months under RH conditions; store in a sealed, cool, and dry place, avoiding high temperatures, light, and moisture.

Chiral characteristics: No chiral center, it is a racemic mixture, geometric isomer purity >99%.