Reaction #1152722

Reaction equation

water

1-bromopentane

sodium cyclopentadienide

hexamethylphosphoramide

→

pentylcyclopentadiene

Yield 85.0%

Solvents

THF

Conditions

Workup

1. 1
   workup.ADDITIONAfter the addition
2. 2
   workup.STIRRINGthe reaction mixture was stirred at -30°-40° C. for 30 minutes and at autogeneous temperature for 30 minutes
3. 3
   Extractionextracted with pentane, (3×80 ml)
4. 4
   Washwashed with water (3×100 ml)
5. 5
   Dryingdried over anhydrous sodium sulfate
6. 6
   Filtrationfiltered
7. 7
   Concentrationconcentrated in a rotary evaporator (water bath temperature 20° C.)
8. 8
   workup.DISTILLATIONThe residue was distilled

Procedure

To a solution of sodium cyclopentadienide (71 mmole, 1.89 M in THF) in 20 ml of THF was added 10 ml of hexamethylphosphoramide. The solution was cooled to -55° C. and 1-bromopentane (10.5 g. 70 mmole) was added dropwise with stirring over a period of 30 min. After the addition was completed, the reaction mixture was stirred at -30°-40° C. for 30 minutes and at autogeneous temperature for 30 minutes, then poured into cold water and extracted with pentane, (3×80 ml). The pentane extracts were combined, washed with water (3×100 ml) dried over anhydrous sodium sulfate, filtered and concentrated in a rotary evaporator (water bath temperature 20° C.). The residue was distilled to give 8.1 g (85%) of pentylcyclopentadiene, b.p. 52°/8 mm Hg.

Source