Methyl trifluoromethyl ketone → 1,1,1-Trifluoro-2,5-dimethylhexa-2,4-diene

A stirred solution of 144.3 g (0.39 mole) of (3-methyl-2-butenyl)triphenylphosphonium cloride in 300 ml of methylene chloride, under nitrogen atmosphere, was cooled to 0° C. To this cold solution a solution of 84.2 g (0.39 mole) of sodium methoxide 25% in methanol was added dropwise at a rate to keep the reaction mixture temperature below 4° C. Upon complete addition (40 minutes) a solution of 50.4 g (0.45 mole) of 1,1,1-trifluoroacetone in 5 ml of methylene chloride was added dropwise at a rate to keep the reaction mixture temperature below 6° C. Upon complete addition (40 minutes) the reaction mixture was allowed to warm to ambient temperature and was then stirred for 18 hours. The reaction mixture was washed twice with 150 ml portions of water, then dried with magnesium sulfate. The mixture was filtered and the filtrate concentrated by distillation. Pentane was added to the pot residue to precipitate triphenylphosphine oxide. The mixture was filtered and the filtrate concentrated by distillation. Diglyme was added to the pot residue, and an additional amount of triphenylphosphene oxide was collected by filtration. The filtrate was fractionally distilled by a spinning band distilling system to give in sixteen fractions 14.2 g of 98% 2-methyl-5-trifluoromethyl-2,4-hexadiene; b.p. 122°-124° C. The nmr spectrum was consistent with the assigned structure.

1. customthe reaction mixture temperature below 4° C
2. additionwas added dropwise at a rate
3. customthe reaction mixture temperature below 6° C
4. additionUpon complete addition (40 minutes) the reaction mixture
5. washThe reaction mixture was washed twice with 150 ml portions of water
6. dry with materialdried with magnesium sulfate
7. filtrationThe mixture was filtered
8. concentrationthe filtrate concentrated by distillation
9. additionPentane was added to the pot residue
10. customto precipitate triphenylphosphine oxide
11. filtrationThe mixture was filtered
12. concentrationthe filtrate concentrated by distillation
13. additionDiglyme was added to the pot residue
14. filtrationan additional amount of triphenylphosphene oxide was collected by filtration
15. distillationThe filtrate was fractionally distilled by a spinning band
16. distillationdistilling system

ORD record

ord-524807d83f994eaab949c4c6e8548135

Source dataset

uspto-grants-1981_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04243677