Oxalic Acid → 2-Pentylidenecyclopentanone

HRID 2308067Notes

Reaction equation

HRID 2308067 reaction equation
O[CH:2]([CH:7]1[CH2:11][CH2:10][CH2:9][C:8]1=[O:12])[CH2:3][CH2:4][CH2:5][CH3:6].C(O)(=O)C(O)=O>C1(C)C=CC=CC=1>[CH:2](=[C:7]1[CH2:11][CH2:10][CH2:9][C:8]1=[O:12])[CH2:3][CH2:4][CH2:5][CH3:6]

Participants

4

Reactant 2

HCID 971Oxalic AcidHCID 162060Cyclopentanone, 2-(1-hydroxypentyl)-

Product 1

HCID 860002-PentylidenecyclopentanoneYield 83.1%

Reagents, catalysts & solvents 1

HCID 1140TolueneSolvent

Procedure

In a 300 ml four-neck flask fitted with a thermometer, a reflux condenser and a stirrer were placed 2-(1-hydroxypentyl)cyclopentanone (70 g) synthesized in Reference Example 1, oxalic acid (0.7 g) and toluene (140 ml), and the whole was refluxed to allow dehydration to proceed. The formed water was removed and the reaction was continued until water was not formed any more (about 2.5 hours). The reaction mixture was washed with water and the layers were separated from each other. The resulting organic layer was further washed with saturated brine and separated. The organic layer was evaporated on a rotary evaporator under reduced pressure to recover toluene and unreacted cyclopentanone, whereby a crude product (63 g) was obtained. The product was distilled using a Widmer distillation apparatus to obtain 52 g of 2-pentylidenecyclopentanone (boiling point: 92° C./533 Pa).

Workup

  1. customIn a 300 ml four-neck flask fitted with a thermometer, a reflux condenser and a stirrer
  2. temperaturethe whole was refluxed
  3. customThe formed water was removed
  4. customwas not formed any more (about 2.5 hours)
  5. washThe reaction mixture was washed with water
  6. customthe layers were separated from each other
  7. washThe resulting organic layer was further washed with saturated brine
  8. customseparated
  9. customThe organic layer was evaporated on a rotary evaporator under reduced pressure
  10. customto recover toluene and unreacted cyclopentanone, whereby a crude product (63 g)
  11. customwas obtained
  12. distillationThe product was distilled
  13. distillationa Widmer distillation apparatus

Sources & evidence

ORD record
ord-0aafa4b1cb0644d48e8cd873e8d982d3
Source dataset
uspto-grants-2004_12
Patent number
US06833481B2

Reaction notes

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