2,6,6-trimethylcyclohex-2-ene-1,4-dione

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:100.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 500 ml flask was fed 10.0 g of reactant mixture containing 8.64% of trimethylhydroquinone diacetate, 6.24% of a mixture of 4-acetoxy-2,3,6-trimethylphenol and 4-acetoxy-2,3,5-trimethylphenol, and 75.7% of 4-oxoisophorone, and the flask was displaced with nitrogen. Then, 50.0 g of water, 1.0 g of 97% sulfuric acid and 11.3 g of acetic acid were added to the above reactants and they were stirred at 100° C. for 2 hours under atmospheric pressure. The reaction mixture was cooled to a room temperature and 30 ml of hexane was added. The deposited crystals were filtered off to obtain 0.941 g of trimethylhydroquinone at a yield of 90.0%. The purity of these crystals was 100% according to the gas chromatographic analysis. With the retention time in gas chromatography and the identification with a standard sample by the results of IR absorption and MS analysis, it was confirmed that the crystals were trimethylhydroquinone. To a 500 ml flask was fed The reaction mixture was cooled to a room temperature The deposited crystals were filtered off

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The water phase (190 liters+5 liters of wash-water) is stirred out five times with 60 liters of methylene chloride each time. The solvent phase is separated, washed twice with 60 liters of water each time and concentrated to about 15 liters on a rotary evaporator. This concentrate is dehydrated with 1.5 kg of sodium sulphate, filtered and concentrated to dryness under reduced pressure. The residue (1755 g) is dissolved while hot in 6 liters of diisopropyl ether, decolourised with 80 g of active carbon, filtered over diatomaceous earth padding and rinsed with 1.8 liters of hot diisopropyl ether. From this solution, 2.6 liters of diisopropyl ether are distilled off at normal pressure, such that the product remains dissolved in a three-fold amount of diisopropyl ether. The product is crystallised overnight at 5° C., filtered off under suction, washed twice with 1500 ml of cold n-hexane each time and dried for 15 hours at 40° C. under reduced pressure. This first crystallisation produces 1280 g of optically pure [6R]-2,2,6-trimethyl-1,4-cyclohexanedione of melting point 91°-92° C. The mother liquor contains a further 447 g of substances. The latter is taken up in the same amount of n-hexane, treated with diisopropyl ether until the solution is clear, crystallised overnight at 5° C., filtered off under suction and washed twice with a small amount of cold n-hexane. The crystallisate is dried at 40° C. under reduced pressure. This second crystallisation produces 83.6 g of product with a melting point of 70°-88° C. After triple recrystallisation with the three-fold amount of diisopropyl ether, there are obtained a further 43 g of optically pure [6R]-2,2,6 -trimethyl-1,4-cyclohexanedione of melting point 90.5°-91.5° C. The solvent phase is separated washed twice with 60 liters of water each time concentrated to about 15 liters on a rotary evaporator filtered concentrated to dryness under reduced pressure The residue (1755 g) is dissolved while hot in 6 liters of diisopropyl ether filtered over diatomaceous earth padding rinsed with 1.8 liters of hot diisopropyl ether From this solution, 2.6 liters of diisopropyl ether are distilled off at normal pressure, such that the product remains dissolved in a three-fold amount of diisopropyl ether The product is crystallised overnight at 5° C. filtered off under suction washed twice with 1500 ml of cold n-hexane each time dried for 15 hours at 40° C. under reduced pressure This first crystallisation

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: The water phase (190 liters+5 liters of wash-water) is stirred out five times with 60 liters of methylene chloride each time. The solvent phase is separated, washed twice with 60 liters of water each time and concentrated to about 15 liters on a rotary evaporator. This concentrate is dehydrated with 1.5 kg of sodium sulphate, filtered and concentrated to dryness under reduced pressure. The residue (1755 g) is dissolved while hot in 6 liters of diisopropyl ether, decolourised with 80 g of active carbon, filtered over diatomaceous earth padding and rinsed with 1.8 liters of hot diisopropyl ether. From this solution, 2.6 liters of diisopropyl ether are distilled off at normal pressure, such that the product remains dissolved in a three-fold amount of diisopropyl ether. The product is crystallised overnight at 5° C., filtered off under suction, washed twice with 1500 ml of cold n-hexane each time and dried for 15 hours at 40° C. under reduced pressure. This first crystallisation produces 1280 g of optically pure [6R]-2,2,6-trimethyl-1,4-cyclohexanedione of melting point 91°-92° C. The mother liquor contains a further 447 g of substances. The latter is taken up in the same amount of n-hexane, treated with diisopropyl ether until the solution is clear, crystallised overnight at 5° C., filtered off under suction and washed twice with a small amount of cold n-hexane. The crystallisate is dried at 40° C. under reduced pressure. This second crystallisation produces 83.6 g of product with a melting point of 70°-88° C. After triple recrystallisation with the three-fold amount of diisopropyl ether, there are obtained a further 43 g of optically pure [6R]-2,2,6 -trimethyl-1,4-cyclohexanedione of melting point 90.5°-91.5° C. The solvent phase is separated washed twice with 60 liters of water each time concentrated to about 15 liters on a rotary evaporator filtered concentrated to dryness under reduced pressure The residue (1755 g) is dissolved while hot in 6 liters of diisopropyl ether filtered over diatomaceous earth padding rinsed with 1.8 liters of hot diisopropyl ether From this solution, 2.6 liters of diisopropyl ether are distilled off at normal pressure, such that the product remains dissolved in a three-fold amount of diisopropyl ether The product is crystallised overnight at 5° C. filtered off under suction washed twice with 1500 ml of cold n-hexane each time dried for 15 hours at 40° C. under reduced pressure This first crystallisation

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 2-liter flask fitted with a reflux condenser, a water separator and a stirrer is charged 265 g of 2,6,6-trimethylcyclohex-2-en-1,4-dione (prepared by the method described in Helv. Chim. Acta, 39:2041 [1956]), 266 g of propylene glycol, 500 ml of benzene and 1 g of p-toluenesulfonic acid. The reactants are stirred and refluxed until no additional water is collected in the water separator. The product is washed with water to a pH of 6, and the solvent is stripped off. The residue is vacuum distilled through a 9" Goodloe column to yield 257 g of product, boiling point 92° C. at 1 mm Hg (80% yield). To a 2-liter flask fitted with a reflux condenser prepared by the method is collected in the water separator The product is washed with water to a pH of 6 distilled through a 9" Goodloe column

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 2-liter flask fitted with a reflux condenser, a water separator and a stirrer is charged 265 g of 2,6,6-trimethylcyclohex-2-en-1,4-dione (prepared by the method described in Helv. Chim. Acta, 39:2041 [1956]), 266 g of propylene glycol, 500 ml of benzene and 1 g of p-toluenesulfonic acid. The reactants are stirred and refluxed until no additional water is collected in the water separator. The product is washed with water to a pH of 6, and the solvent is stripped off. The residue is vacuum distilled through a 9" Goodloe column to yield 257 g of product, boiling point 92° C. at 1 mm Hg (80% yield). To a 2-liter flask fitted with a reflux condenser prepared by the method is collected in the water separator The product is washed with water to a pH of 6 distilled through a 9" Goodloe column

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 2-liter flask fitted with a reflux condenser, a water separator and a stirrer is charged 265 g of 2,6,6-trimethylcyclohex-2-en-1,4-dione (prepared by the method described in Helv. Chim. Acta, 39:2041 [1956]), 266 g of propylene glycol, 500 ml of benzene and 1 g of p-toluenesulfonic acid. The reactants are stirred and refluxed until no additional water is collected in the water separator. The product is washed with water to a pH of 6, and the solvent is stripped off. The residue is vacuum distilled through a 9" Goodloe column to yield 257 g of product, boiling point 92° C. at 1 mm Hg (80% yield). To a 2-liter flask fitted with a reflux condenser prepared by the method is collected in the water separator The product is washed with water to a pH of 6 distilled through a 9" Goodloe column

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: To a 2-liter flask fitted with a reflux condenser, a water separator and a stirrer is charged 265 g of 2,6,6-trimethylcyclohex-2-en-1,4-dione (prepared by the method described in Helv. Chim. Acta, 39:2041 [1956]), 266 g of propylene glycol, 500 ml of benzene and 1 g of p-toluenesulfonic acid. The reactants are stirred and refluxed until no additional water is collected in the water separator. The product is washed with water to a pH of 6, and the solvent is stripped off. The residue is vacuum distilled through a 9" Goodloe column to yield 257 g of product, boiling point 92° C. at 1 mm Hg (80% yield). To a 2-liter flask fitted with a reflux condenser prepared by the method is collected in the water separator The product is washed with water to a pH of 6 distilled through a 9" Goodloe column

Conditions: temp:60.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 23.2 g (106.3 mmol) of di-tert.-butyl dicarbonate in 25 ml of tetrahydrofuran was added dropwise to a suspension, stirred at 24° C., of 20.0 g (144.7 mmol) of K2CO3, 20 ml of tetrahydrofuran, 1.1 g (4.2 mmol) of 18-crown-6 and 15.2 g (100 mmol) of ketoisophorone. The suspension was stirred at 60° C. for 5 hours, then the brown reaction mixture was filtered and finally the solvent was evaporated. The brown residue (26.6 g) was dissolved in 200 ml of dichloromethane and the solution was extracted with saturated NaHCO3 solution and with water. The organic phase was dried over Na2SO4, filtered and evaporated. The brown residue (22.6 g) was chromatographed over 150 g of silica gel (n-hexane/ether 2/1). There were obtained 20.4 g (81%) of 4-tert.-butyloxycarbonyloxy-2,6,6-trimethylcyclohexa-2,4-dienone as a yellow oil; anal. calc. for C14H20O4 (252.31): C 66.65, H 7.99; found: C 66.46, H 8.08.1H-NMR (250 MHz, CDCl3): 1.25 (s, 2 CH3 --C(6)); 1.54 (s, (CH3)3C--O); 1.91 (s, CH3 --C(2); 5.88-5.89 (d, H--C(5)); 6.71-6.74 (m, H--C(5) the brown reaction mixture was filtered finally the solvent was evaporated The brown residue (26.6 g) was dissolved in 200 ml of dichloromethane the solution was extracted with saturated NaHCO3 solution and with water The organic phase was dried over Na2SO4 filtered evaporated The brown residue (22.6 g) was chromatographed over 150 g of silica gel (n-hexane/ether 2/1)