2-BROMO-2-PROPYLPENTANOIC ACID ETHYL ESTER → HCID 54033083, compound

A solution of 100 g of triethylene diamine (1,4-diazabicyclo[2,2,2]-octane) in 400 ml of acetonitrile are added to a solution of 100 g of 2-bromo-2-propyl pentanoic acid ethyl ester in 200 ml of acetonitrile. The colourless reaction mixture is refluxed for 8 hours and precipitation of a white salt starts after only 15 minutes. Subsequently approximately 450 ml of acetonitrile are distilled off and recovered on the rotary evaporator at 200 mbar and 40° C. The oily-crystalline residue is mixed with 1000 ml of water, accompanied by the dissolving of the separated salt. After acidifying with 1N hydrochloric acid to pH 1, the separated oil is taken up in 150 ml of n-hexane and the aqueous phase is extracted twice more with in each case 150 ml of n-hexane. After washing and drying the organic phase, distillation takes place. The yield is 54.3 g of a mixture of E and Z-2-propyl-2-pentenoic acid ethyl ester with a content of 42 g of the sought E-isomer, corresponding to 62% based on the starting product.

1. temperatureThe colourless reaction mixture is refluxed for 8 hours
2. customprecipitation of a white salt starts after only 15 minutes
3. distillationSubsequently approximately 450 ml of acetonitrile are distilled off
4. customrecovered on the rotary evaporator at 200 mbar and 40° C
5. additionThe oily-crystalline residue is mixed with 1000 ml of water
6. dissolutiondissolving of the separated salt
7. extractionthe aqueous phase is extracted twice more with in each case 150 ml of n-hexane
8. washAfter washing
9. customdrying
10. distillationthe organic phase, distillation

ORD record

ord-f8bc729071aa456c9792244547a6f5f8

Source dataset

uspto-grants-1990_10

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04966996