Bitertanol synthesis

Yield:-

Reaction Conditions:

in water;isopropyl alcohol

Steps:

(Semi-technical scale)
(Semi-technical scale) 2,000 liters of isopropanol, 637 kg of 1-(4-biphenylyloxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-one and 200 kg of aluminum isopropylate are mixed by stirring in a 3,000 lit stirred kettle. The mixture is heated to the boil (80° C.), while stirring. The kettle is closed in a pressure-tight manner and is heated further until an internal temperature of 115° C. has been reached, which corresponds to a kettle pressure of 1.5 to 2 bar. The progress of the reaction is monitored by gas chromatography, until complete reduction has been achieved. The reaction time is 4 to 6 hours. The contents of the kettle are cooled until normal pressure has been reached. The kettle is opened. Part of the solvent is removed by distillation (approximately 1,000 liters). 1,050 kg of 15 percent strength sulphuric acid are initially taken (20° C.) in a second 3,000 liter stirred kettle. The warm, approximately 70° C., residue from the distillation of the reaction mixture is added, while stirring. After the addition, the mixture is stirred for one hour at 60° C. A liquid two-phase mixture is formed when employing this procedure. The phases are separated at 60° C. via a heated separating vessel. The organic phase is added slowly at 60° C., and while stirring, to a mixture of 2,000 liters of water and 45 kg of 45% strength sodium hydroxide solution which is initially taken, at 20° C., in a 5,000 liter stirred kettle. In the course of this the reaction product crystallizes. When the addition is complete, the contents of the kettle are cooled to 10° C. and the crystalline product is isolated on a stirred pressure filter. The filter cake is washed with water until it is neutral and is dried to constant weight in vacuo at 50° C. This gives 609 kg (95% of theory) of 1-(4-biphenylyloxy)-3,3-dimethyl-1-(1,2,4-triazol-1-yl)-butan-2-ol having a threo content of 85% and a melting range of 105°-131° C.

References:

Bayer Aktiengesellschaft US4510314, 1985, A

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