Phosphorus oxychloride → Pyrazine, 2-chloro-3-ethyl-

HRID 343366Notes

Reaction equation

HRID 343366 reaction equation
[CH2:1]([C:3]1[C:4](O)=[N:5][CH:6]=[CH:7][N:8]=1)[CH3:2].P(Cl)(Cl)([Cl:12])=O>>[Cl:12][C:4]1[C:3]([CH2:1][CH3:2])=[N:8][CH:7]=[CH:6][N:5]=1

Participants

3

Reactant 2

HCID 24813Phosphorus oxychlorideHCID 178437669HCID 178437669, compound

Product 1

HCID 113222Pyrazine, 2-chloro-3-ethyl-Yield 98%

Procedure

3-Ethyl-2-hydroxypyrazine (5 g) was heated with phosphorus oxychloride (15 ml) at reflux for 3 hours. The reaction was allowed to cool to ambient temperature and then poured onto 200 g of crushed ice. The mixture was extracted with dichloromethane (3×150 ml) and the combined extracts were dried (MgSO4). Volatile material was removed by evaporation to give a brown oil. The oil was purified by chromatography on silica gel, eluting with dichloromethane, to give 2-chloro-3-ethylpyrazine as a colourless oil (5.64 g, 98%); 1H NMR (d6 -DMSO, 200 MHz): 1.25 (t,3H), 2.93 (q,2H), 8.36 (d,1H), 8.59 (d,1H); mass spectrum (+ve CI): 143 (M+H)+.

Workup

  1. temperatureat reflux for 3 hours
  2. extractionThe mixture was extracted with dichloromethane (3×150 ml)
  3. dry with materialthe combined extracts were dried (MgSO4)
  4. customVolatile material was removed by evaporation
  5. customto give a brown oil
  6. customThe oil was purified by chromatography on silica gel
  7. washeluting with dichloromethane

Sources & evidence

ORD record
ord-04ee99e486ce4221a849a4bbca74ef5a
Source dataset
uspto-grants-1999_01
Patent number
US05861401

Reaction notes

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