3,3-Dimethylcyclohexanone synthesis

Yield:2979-19-3 98%

Reaction Conditions:

with hydrogen;Amberlyst CH₅₇ in methanol at 85; under 3750.38 Torr; for 7.5 h;Product distribution / selectivity;Autoclave;

Steps:

3

General procedure for examples 1-7:; Amberlyst CH57 (1 g cat per g dimedone; = 1 mol% Pd in relation to dimedone) was placed in a glass-liner. 4.38 g (31 mmol) of dimedone and ca. 15 g of the solvent (leading to a 20 weight-% solution of dimedone) were added. The glass-liner was closed and stirring was started. The autoclave was flushed three times with 5 bara N₂. The stirrer was turned off. The autoclave was pressurized with 5 bara H₂ (i.e. 1 bar atmospheric pressure + 4 bar H₂ pressure) for 10 minutes for pressure check. The pressure was released. The stirrer was turned on again and the autoclave was heated to 85°C internal temperature. The autoclave was pressurized with H₂ and the stirrer was set on. The reaction mixture was stirred under H₂-pressure at 85°C until hydrogen uptake had ceded (when the hydrogenation curve is horizontal, usually after 110% of theoretical H₂-amount). Then the autoclave was cooled to a temperature below 25°C and depressurized. After three times flushing with N₂ at 5 bara for 10 minutes stirring was stopped and the autoclave was opened. The content was sucked and filtrated over a 0.45 μm filter. A 30 μL filtrated sample was diluted with 1 mL of isopropanol and 5 mg of NaHCO₃ and then analyzed by GC.; * Example 3: Exp. 20804 Hydrogenation in methanol at a larger scale; 37 g of Amberlyst CH57 were placed in a 500 mL glass-liner. 32 g of dimedone (221 mmol) and 116 g of methanol (147 mL) were added. The glass-liner was closed and stirring was started with 500 rpm. The autoclave was flushed three times with 5 bara N₂. The stirrer was turned off. The autoclave was pressurized with 5 bara H₂ for 10 minutes for pressure check. The pressure was released. The stirrer was turned on to 1000 rpm and the autoclave was heated to 85°C internal temperature. The autoclave was pressurized with 2 bara H₂ and the stirrer was set to 1000 rpm. The reaction mixture was stirred under 2 bara H₂ at 85°C for 7.5 hours. Then the autoclave was cooled to a temperature below 25°C and depressurized. After three times flushing with N₂ at 5 bara for 10 minutes stirring was stopped and the autoclave was opened. The content was sucked and filtrated over a 0.45 μm filter. A 30 μL filtrated sample was diluted with 1 mL of isopropanol and 5 mg of NaHCO₃ and then analyzed by GC. The total yield of 3,3-dimethylcyclohexanone was 98% with a selectivity of 98 %. Here 37 g of Amberlyst CH57; 32 g of dimedone (221 mmol) and 116 g of methanol (147 mL) were used showing that the process of the present invention may also be successfully, i.e. with high yield and selectivity, carried out at a larger scale.

References:

EP2128118,2009,A1 Location in patent:Page/Page column 7-8