Sulfalen Chemical Properties

Melting point:

176°

Boiling point:

488.6±55.0 °C(Predicted)

Density 

1.3936 (rough estimate)

refractive index 

1.6200 (estimate)

storage temp. 

Keep in dark place,Inert atmosphere,Room temperature

solubility 

DMSO (Slightly), Methanol (Slightly, heated)

form 

Solid

pka

pKa 6.20(H2O t = 25.0±0.5 I = 0.2) (Uncertain)

color 

White to Yellow

λmax

250nm(NaOH aq.)(lit.)

Merck 

14,8910

CAS DataBase Reference

152-47-6(CAS DataBase Reference)

Safety Information

RTECS 

WP0175000

HS Code 

2935.90.9500

HazardClass 

IRRITANT

Toxicity

LD50 in mice (g/kg): 2.164 orally; 1.41 i.v. (US 3098069)

Sulfalen Usage And Synthesis

Chemical Properties

White to Yellow Solid

Originator

Longum,Farmitalia,W. Germany,1962

Uses

A possible antimalarial drug.

Definition

ChEBI: Sulfamethopyrazine is a member of pyrazines, a sulfonamide and a sulfonamide antibiotic.

Manufacturing Process

2-Amino-3,5-Dibromo-Pyrazine: 112.7 ml of bromine in 375 ml of acetic acid are slowly added at 0° to +2°C, while stirring, to a solution of 95.11 grams of 2-amino-pyrazine and 326.5 grams of acetic acid trihydrate (CH3COONa·3H2O) in 1,480 ml of acetic acid. This addition requires about 2 to 3 hours and it is carried out in the dark. The mixture is then allowed to stand at room temperature (25° to 30°C) for 15 to 16 hours. About 1.5 liters of acetic acid are distilled off under vacuum (12 to 14 mm Hg) at 35°C and the brown and viscous residue is poured into 500 grams of ice-water under stirring.
Aqueous 20% sodium hydroxide is added in order to obtain a pH = 8 and then the product is filtered and air-dried. The air-dried product is extracted 6 times with 150 ml of ether; the filtered ethereal solutions are evaporated to dryness and the residue (50 to 52 grams) is crystallized from hot water. The yield is 34.36 grams, melting at 114°C.
2-Amino-3-Methoxy-5-Bromo-Pyrazine: 7 grams of 2-amino-3,5-dibromopyrazine are boiled for 9 hours in a methanolic solution of sodium methylate (obtained from 0.65 gram of Na and 18.5 ml of methanol). By cooling a crystalline product is obtained, filtered and washed once with methanol and 2 to 3 times with water. The yield is 5.4 grams, melting at 138°C.
2-Amino-3-Methoxy-Pyrazine: 3 grams of 2-amino-3-methoxy-5-bromopyrazine are hydrogenated, in methanolic solution at room temperature and at atmospheric pressure, in the presence of 1 gram of palladium over charcoal (10%) and 0.9 gram of potassium hydroxide. When the stoichiometric amount of hydrogen is absorbed, the suspension is filtered and the filtrate is evaporated to dryness. The residue is extracted with acetone, the acetonic solution is evaporated and the residue (1.8 grams, melting at 75° to 82°C) is crystallized from cyclohexane. The yield is 1.5 grams, melting at 85°C.
2-(p-Acetylaminobenzene-sulfonamido)-3-Methoxy-Pyrazine: 1.5 grams of 2- amino-3-methoxy-pyrazine dissolved in 15 ml of anhydrous pyridine are treated, under cooling and stirring, with 2.81 grams of pacetylaminobenzenesulfonyl chloride, at small portions in about 30 minutes. The mixture is allowed to stand for 20 hours at room temperature and then is heated to 50°C for 4 hours.
The solution is concentrated to one-third of its volume, under vacuum, and poured into ice-water under stirring. The precipitate is filtered and washed with water. 2.21 grams melting at 218° to 220°C are obtained. The MP (crystallized from alcohol) is 224°C.
2-Sulfanilamido-3-Methoxy-Pyrazine: 1.5 grams of the product from the preceding step and 7 to 8 ml of aqueous 10% sodium hydroxide are boiled for 1 hour. The cooled solution is slightly acidified to pH 6 with aqueous 2 N hydrochloric acid and the product is filtered. The yield is 1.25 grams, melting at 175°C.

brand name

Kelfizina (Abbott).

Therapeutic Function

Antibacterial

Pharmaceutical Applications

2-Sulfanilamido-3-methoxypyrazine. A very long-acting compound (plasma half-life 60 h). Adequate blood levels can be maintained by giving a dose of 2 g once weekly. The protein binding is c. 70%. It has been successfully used in the single-dose treatment of urinary tract infection. As with other long-acting compounds, sulfametopyrazine has been associated with an increased incidence of erythema multiforme.

Synthesis

Sulfalene, 3-methoxy-2-sulfanilamidopyrazine (33.1.41), like other sulfanilamides, is synthesized by the standard scheme from 4-acetylaminobenzenesulfonyl chloride, which is reacted with 3-amino-2-methoxypyrazine, which is synthesized by two technologically available methods. The first of these methods consists of direct bromination of 2-aminopyrazine using acetic acid as a solvent, which gives 3,5-dibromo-2-aminopyrazine (33.1.34). Reacting this with sodium methoxide gives 3-methoxy-5-bromo-2-aminopyrazine (33.1.35). Hydrogen reduction using a palladium on carbon catalyst replaces the bromine atom at C5 of the product with a hydrogen atom, giving 3-methoxy-2-aminopyrazine (33.1.36).
This same 3-methoxy-2-aminopyrazine (33.1.36) is synthesized from 3-hydroxypyrazin- 2-carboxamide. Reacting this with phosphorous oxychloride replaces the hydroxyl group with a chlorine atom while the carboxamide group simultaneously undergoes dehydration to form 3-chloro-2-cyanopyrazine (33.1.37). Next, reacting this with sodium methoxide gives 3-methoxy-2-cyanopyrazine (33.1.38). The cyano group in this compound is hydrolyzed by a base in the presence of hydrogen peroxide to a carboxamide group, giving 3-methoxy-2-carboxamideopyrazine (33.1.39). The resulting product undergoes a Hofmann rearrangement when reacted with sodium hypochlorite, giving the desired 3-methoxy-2 aminopyrazine (33.1.36). Reacting this with 4-acetylaminobenzenesulfonyl chloride and subsequent hydrolysis of the acetyl group with a base to (33.1.40) gives sulfalene.

Sulfalen(152-47-6)Related Product Information

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