Water → 2-Thiophen-2-yl-piperazine

HRID 462414Notes

Reaction equation

HRID 462414 reaction equation
[CH2:1]([NH2:4])[CH2:2][NH2:3].O.[S:6]1[CH:10]=[CH:9][CH:8]=[C:7]1[C:11]([CH:13]=O)=O.[BH4-].[Na+].O>C(O)C>[S:6]1[CH:10]=[CH:9][CH:8]=[C:7]1[CH:11]1[CH2:13][NH:4][CH2:1][CH2:2][NH:3]1

Participants

6

Reactant 4

HCID 962WaterHCID 3301EthylenediamineHCID 4311764Sodium borohydrideHCID 122504572-Oxo-2-(thiophen-2-yl)acetaldehyde hydrate

Product 1

HCID 27717262-Thiophen-2-yl-piperazine

Reagents, catalysts & solvents 1

HCID 702EthanolSolvent2×

Procedure

A solution of ethylenediamine (4.1 g, 0.068 mol) in ethanol (25 ml) is added dropwise to a solution of 2-thienylglyoxal hydrate [prepared by the procedure of F. Kipnis and J. Ornfelt, J. Amer. Chem. Soc. 68, 2734 (1946)] (10.0 g, 0.063 mol) in ethanol (250 ml) at 0° C. under an atmosphere of dry nitrogen. The cooling bath is removed and the reaction mixture stirred for an additional 1.5 h. Sodium borohydride (4.5 g, 0.126 mol) is added all at once, and a cooling bath used to control the exothermic reaction. Stirring is continued for an additional 18 h. Water (25 ml) is added, and the ethanol removed under reduced pressure. The remaining aqueous solution is extracted with methylene chloride (3×100 ml) and the extracts dried with potassium carbonate. Removal of the solvent under reduced pressure gives 2-(2-thienyl)piperazine as an off-white solid. An analytical sample is obtained by addition of an ethereal solution of the base to an ethereal solution of oxalic acid dihydrate. The resulting precipitate is washed with diethyl ether and methanol, and the free base (m.p. 81°-83° C.) is obtained with a saturated solution of potassium carbonate.

Workup

  1. customprepared by the procedure of F
  2. customat 0° C.
  3. customThe cooling bath is removed
  4. customthe exothermic reaction
  5. stirringStirring
  6. waitis continued for an additional 18 h
  7. customthe ethanol removed under reduced pressure
  8. extractionThe remaining aqueous solution is extracted with methylene chloride (3×100 ml)
  9. dry with materialthe extracts dried with potassium carbonate
  10. customRemoval of the solvent under reduced pressure

Sources & evidence

ORD record
ord-fbdf85fa7d77434a86eede21e0a17ab5
Source dataset
uspto-grants-1985_05
Patent number
US04515792

Reaction notes

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