Dimethylformamide → Methyl 4-[3-(3,5-dichlorophenyl)-4,4,4-trifluoro-1-oxo-2-buten-1-yl]-1-naphthalenecarboxylate

Participants

Reaction Steps

A mixture of methyl 4-acetyl-1-naphthalenecarboxylate (5.36 g, 23.4 mmol), 1-(3,5-dichlorophenyl)-2,2,2-trifluoroethanone (5.68 g, 23.4 mmol), calcium hydroxide (0.172 g, 2.3 mmol), N,N-dimethylformamide (16 mL), and tert-butyl methyl ether (32 mL) was placed in a thermometer-equipped reaction vessel. The reaction vessel was connected to a ten-plate Oldershaw column, the output of which was condensed and fed into a decanter initially filled with tert-butyl methyl ether. A nitrogen atmosphere was maintained in the apparatus. The upper part of the decanter was connected to return condensate to the fifth plate of the Oldershaw column. This arrangement ensured that wet (containing dissolved water) tert-butyl methyl ether from the decanter was not returned to the reaction vessel. A drain valve at the bottom of the decanter allowed removing tert-butyl methyl ether in addition to water from the decanter. The reaction mixture was heated to distill the tert-butyl methyl ether/water azeotrope. As the decanter trap contained an amount of tert-butyl methyl ether sufficient to dissolve all of the water formed by the reaction, the condensate in the trap did not separate into layers containing predominately water and predominately tert-butyl methyl ether. Because the reaction mixture initially contained mostly tert-butyl methyl ether, the mixture boiled at a temperature not much exceeding the normal boiling point of tert-butyl methyl ether (e.g., about 65-70° C.). The reaction appeared to proceed relatively slowly at this temperature, so condensate was gradually drained from the decanter trap to remove tert-butyl methyl ether. As the concentration of tert-butyl methyl decreased in the reaction mixture, the temperature of the boiling mixture increased. Tert-butyl methyl ether was removed by draining the decanter until the temperature of the boiling reaction mixture reached about 75 to 80° C. To maintain this temperature range, tert-butyl methyl ether was added as needed to compensate for loss of solvent from the apparatus. The total time from beginning heating the reaction mixture to stopping distillation, not including a shutdown period overnight, was about 15 h. During this time period a further portion of calcium hydroxide (1.34 g, 18.1 mmol) was added to increase the reaction rate.

Provenance & Evidence