ChemicalBook CAS DataBase List 2,5-Dichloropyrazine

2,5-Dichloropyrazine synthesis

10synthesis methods

Product Name:2,5-Dichloropyrazine
CAS Number:19745-07-4
Molecular formula:C4H2Cl2N2
Molecular Weight:148.98

33332-29-5

19745-07-4

Step 2: Synthesis of 2,5-dichloropyrazine To a stirred solution of 5-chloropyrazin-2-amine (1 g, 7.751 mmol) in concentrated hydrochloric acid (10 mL), an aqueous solution of sodium nitrite (1.1 g, 15.89 mmol) was slowly added at -10 °C, and the addition process lasted for 1 hour. After addition, the reaction mixture was stirred at 0 °C for 1 h, and then brought to room temperature and continued stirring for 2 h. The reaction was carried out by thin layer chromatography (TLC). The reaction process was monitored by thin layer chromatography (TLC). Upon completion of the reaction, the reaction mixture was neutralized with 50% sodium hydroxide (NaOH) solution and subsequently extracted with dichloromethane (DCM). The organic layers were combined, dried with anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The crude product was purified by column chromatography on silica gel (100-200 mesh) to afford 2,5-dichloropyrazine (0.59 g, 15% yield) as a colorless oil using hexane solution containing 2% ethyl acetate as eluent. Mass spectrum (MS): 184.1 [M-1].

374063-92-0 Synthesis

374063-92-0
224 suppliers
$7.00/250mg

19745-07-4
201 suppliers
$20.00/1g

912773-21-8
147 suppliers
$9.00/100mg

Yield:19745-07-4 72 g

Reaction Conditions:

with trichlorophosphate at 60; for 2 h;

Steps:

2.1 (1) Preparation of mixture of 2,5-dichloropyrazine and 2-chloro-5-bromopyrazine
Add 50 grams of 2-hydroxypyrazine to 250 milliliters of N,N-dimethyl sulfoxide, reduce the temperature to 10-12°C, add 74 grams of dibromohydantoin in batches, and after holding for 1 hour, add 500 milliliters of water to precipitate a large amount The yellow solid was filtered and dried to obtain 80.1 g of 2-hydroxy-5-bromopyrazine. Add 2-hydroxy-5-bromopyrazine to 341 grams of phosphorus oxychloride and heat up to 60°C for 2 hours, then pour it into 800 grams of ice-water mixture, filter, 350 ml of isopropyl acetate, extract and concentrate to obtain 72 Grams of dark brown oil is a mixture of 2,5-dichloropyrazine and 2-chloro-5-bromopyrazine. The total yield of the two steps is about 79%.

References:

Lanzhou Kangyuxin Biological Technology Co., Ltd.;Zhang Qiaolan CN111471025, 2020, A Location in patent:Paragraph 0067-0069

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33332-29-5 Synthesis

33332-29-5
258 suppliers
$14.00/1g

19745-07-4
201 suppliers
$20.00/1g

References