Pyrazine, 2,5-dichloro-

Pyrazine, 2,5-dichloro- - Names and Identifiers

Name	2,5-Dichloropyrazine
Synonyms	NSC 349788 2,5-Dichloroprazine 2,5-Dichloropyrazine 2,5-DICHLOROPYRAZINE Pyrazine, 2,5-dichloro- 2,5-Dichloro-1,4-diazine
CAS	19745-07-4
InChI	InChI=1/C4H2Cl2N2/c5-3-1-7-4(6)2-8-3/h1-2H

Pyrazine, 2,5-dichloro- - Physico-chemical Properties

Molecular Formula	C4H2Cl2N2
Molar Mass	148.98
Density	1.493±0.06 g/cm3(Predicted)
Melting Point	0 °C (approx)
Boling Point	184.4±35.0 °C(Predicted)
Flash Point	81.5°C
Vapor Presure	1mmHg at 25°C
Appearance	Yellow liquid
pKa	-4.23±0.10(Predicted)
Storage Condition	under inert gas (nitrogen or Argon) at 2-8°C
Refractive Index	1.559

Pyrazine, 2,5-dichloro- - Risk and Safety

Hazard Symbols	Xn - Harmful
Risk Codes	R22 - Harmful if swallowed R41 - Risk of serious damage to eyes
Safety Description	S26 - In case of contact with eyes, rinse immediately with plenty of water and seek medical advice. S39 - Wear eye / face protection.
HS Code	29339900

Pyrazine, 2,5-dichloro- - Reference Information

Application

2,5-dichloropyrazine is a pharmaceutical intermediate that can be chlorinated from pyrazine-2-amine to obtain 5-chloropyrazine-2-amine, and then 2, 5-dichloropyrazine is obtained by diazotization reaction.

Preparation

Step 1: Synthesis of 5-chlorpyrazine-2-amine Under nitrogen, NCS(4.2g,30.545mmol) is added to the stirred solution of pyrazine-2-amine (3g,31.545mmol) in anhydrous DCM(30mL), and stirred at 40°C for 2h. The reaction progress was monitored by TLC. After the reaction is complete, DCM is added and washed with water. The organic layers were dried with sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel (100-200 mesh) column chromatography using 20% ethyl acetate in hexane as eluent to obtain 5-chlorpyrazine-2-amine (0.59g,15%) as a yellow solid. Step 2: Synthesis of 5-dichloropyrazine At -10°C, add sodium nitrite aqueous solution (1.1g,15.89mmol) to the stirred solution of 5-chloropyrazine-2-amine (1g,7.751mmol) in concentrated HCl(10mL) within 1h, stir at 0°C for 1h, and then stir at RT for 2h. The reaction progress was monitored by TLC. After the reaction is completed, the reaction material is neutralized in 50% NaOH solution and extracted with DCM. The organic layers were dried with sodium sulfate and concentrated under reduced pressure. The crude product was purified by silica gel (100-200 mesh) column chromatography using 2% ethyl acetate in hexane as eluent to obtain 2,5-dichloropyrazine (0.59g,15%) as a colorless oil.

Last Update：2024-04-09 15:16:48