Propionic Acid → Ethyl 4-methyl-4-pentenoate

A solution of 2-methyl-2-propen-1-ol (12.9 g, 0.18 mol), triethyl orthoacetate (230.0 mL, 1.3 mol) and propionic acid (0.9 mL, 0.12 mol) was heated to 170° C. (external). The reaction apparatus was equipped with a Vigreaux Claisen adapter with a collection flask to remove the ethanol produced. The reaction mixture was left under reflux overnight. The excess amount of triethyl orthoacetate was gently distilled off at 130 mm Hg until the temperature in the reaction flask began to increase. After the reaction was cool, the remaining liquid was treated with 300 mL of 10% monobasic potassium phosphate and the left reaction was stirred for 90 min at ambient temperature. The reaction mixture was extracted with diethyl ether (3×100 mL). The combined organic phase was dried over Na2SO4 and concentrated in vacuo to give a yellow oil. Flash column chromatography of this oil (silica gel, 4:1 hexane/diethyl ether) afforded compound 7 as a colorless oil (17.0 g, 0.12 mmol, 67%) (Gen et al. (1973) J. Am. Chem. Soc. 95, 2656-2663).

1. customThe reaction apparatus was equipped with a Vigreaux Claisen adapter with a collection flask
2. customto remove the ethanol
3. customproduced
4. waitThe reaction mixture was left
5. temperatureunder reflux overnight
6. distillationThe excess amount of triethyl orthoacetate was gently distilled off at 130 mm Hg until the temperature in the reaction flask
7. temperatureto increase
8. temperatureAfter the reaction was cool
9. additionthe remaining liquid was treated with 300 mL of 10% monobasic potassium phosphate
10. customthe left reaction
11. extractionThe reaction mixture was extracted with diethyl ether (3×100 mL)
12. dry with materialThe combined organic phase was dried over Na2SO4
13. concentrationconcentrated in vacuo
14. customto give a yellow oil

ORD record

ord-fe593eb6297c4de8abe246209f4d643f

Source dataset

uspto-grants-2011_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08022052B2