Synthesis of mono-substituted cyclopentadienes

Synthesis of n-butylcyclopentadiene

CpMgCl (775.4 g, 0.753 mol) THF solution was added to a reaction flask and warmed to about 30° C. 1-Iodobutane (184 g, 0.72 mol) was fed in and allowed to react at about 30° C. to about 40° C. Reaction was checked for the presence of unsubstituted Cp by quenching a sample on water, phase separating and running on a gas chromatograph (GC), wherein additional iodo-reagent was added until the reaction had achieved completeness. Mineral oil (400 g) was added to the reaction flask. The product was isolated by vacuum distillation and trapping in a chilled receiver. The distillate was analyzed by GC yielding mono-substituted n-butylcyclopentadiene at about 13.3% concentration in THF. The yield of n-butylcyclopentadiene was about 90% by weight. See Equation 2.

Synthesis of ethylcyclopentadiene

975 mLs of CpMgCl/THF (1.05M, 1.02 mol) was added to an addition funnel. A 2 L 3-neck round bottom flask, was charged with ethyl-iodide (155.9 g, 1 mol). The Grignard solution was initially fed in at about 30° C. The pot temperature was held at about 30° C. to about 40° C. by periodic application of ice-water bath. Reaction was checked for the presence of ethyl-iodide by gas chromatograph mass spectrometer (GCMS), wherein additional Grignard was added until the reaction had achieved completeness. The reaction was cooled and quenched with water (300 g). Hexane (100 g, 1.16 mol) was added to the flask to aid in partitioning the organic phase from the aqueous phase. The organic phase was collected in a flask and dried over sodium sulfate and filtered. The product was used as the Hexane/THF solution. The mixture was analyzed by GCMS yielding ethylcyclopentadiene at about 15% concentration in Hexane/THF. The yield of ethylcyclopentadiene was about 60% by weight. See Equation 3.

Improved Synthesis of ethylcyclopentadiene (Equation 3)

CpMgCl (581.3 g, 0.663 mol) THF solution was concentrated under rough pump in a reaction flask. Iodo-ethane (100 g, 0.64 mol) was added in at elevated temperatures. The pot temperature was tempered at about 30° C. to about 40° C. by periodic application of ice-water bath. Reaction was checked for the presence of iodo-ethane by quenching a sample on water, phase separating and running on a GC, wherein additional Grignard was added until the reaction had achieved completeness. Because the reaction was not complete, three additional shots of Grignard were added. Mineral oil (308 g) was added to the reaction flask. The product was isolated by vacuum distillation. The distillate was analyzed by GC yielding mono-substituted ethylcyclopentadiene at about 14.8% concentration in THF. The yield of ethylcyclopentadiene was about 80.4% by weight.

Synthesis of n-but-1-enyl-cyclopentadiene

4-iodo-butene (308.8 g, 1.646 mol) was added to a reaction flask and warmed to a temperature ranging from about 35° C. to about 50° C. 1.707 L CpMgCl (0.995 M, 1.698 mol) was slowly added in at about 35° C. to about 50° C. Reaction was checked for the presence of unreacted 4-iodo-butene by quenching a sample on water, phase separating and running on a GC, wherein additional iodo-reagent was added until the reaction had achieved completeness. The mixture was concentrated by atmospheric distillation of excess THF. Mineral oil (700 ml) was added to the reaction flask. The product was isolated by vacuum distillation in mineral oil. The distillate was analyzed by GC yielding mono-substituted butenyl-cyclopentadiene at about 27% concentration in THF. The yield of n-but-1-enyl-cyclopentadiene was about 91.7% by weight. See Equation 4.

Synthesis of n-propylcyclopentadiene

To a 2 L 3-neck round bottomed flask containing 1.079 g CpMgCl (1.03 mol/kg solution, 1.111 mol), 1-Iodopropane (178 g, 1.047 mol) was added dropwise over 45 minutes. The reaction temperature was kept in the range of 30° C. to 40° C. Mineral oil (480 g) was added to the reaction flask. The product was isolated as a THF solution by vacuum distillation from the mineral oil (551 g of co-distillate). The distillate was analyzed by GCMS affording mono-substituted propylcyclopentadiene at 11.4% concentration in THF (62.8 g contained, 58.5% yield). See Equation 5.

While a number of exemplifying features and embodiments have been discussed above, those with skill in the art will recognize certain modifications, permutations, additions and subcombinations thereof. No limitation with respect to the specific embodiments disclosed herein is intended or should be inferred.