Manufacturing Process
(1) 1,2-Dibromo-2-(2-chloro)ethoxyethane: 640 g of bromine (4 mols) are added dropwise, with stirring, to 426 g (4 mols) of 2-chloroethylvinyl ether dissolved in 1,040 ml of chloroform maintained at -10°C.
When addition is ended, the solvent and then the residue are distilled in vacuum to obtain 690 g of product. Yield = 65%.
(2) 2-(3-Trifluoromethyl)-2-(2-chloro)ethoxy-1-bromoethane: (3Trifluoromethyl)phenyl magnesium bromide is prepared under the normal conditions for magnesium derivatives, from 48.6 g of magnesium turnings and 455.7 g of (3-trifluoromethyl)bromobenzeneand 1.5 liters anhydrous ether.
To the solution of the magnesium compound so obtained the following solution is added dropwise, with stirring so as to maintain a slight reflux of ether: 1,2dibromo-2-(2-chloro)-ethoxyethane: 550 g. Anhydrous ether: 300 ml.
After the addition, reflux heating is continued for two hours, cooling is carried out and there is hydrolysis by the mixture: Ice: 500 g. Concentrated HCl: 200 ml.
The organic phase is decanted, washed in NaCl saturated water and dried on anhydrous Na2SO4; the ether is distilled and the residue is rectified in vacuum to obtain 361 g of the product. Yield = 54%.
According to gas phase chromatography, the product so obtained is about 95% pure and it can be used in further reactions without a second rectification.
(3) 2-(3-Trifluoromethyl)phenyl-4-isopropyl tetrahydro-1,4-oxazine hydrochloride: The following mixture is heated in an autoclave at 100°C; 2-(3trifluoromethyl)-2-(2-chloro)-ethoxy-1-bromoethane: 33.15 g (0.1 mol); isopropylamine: 20 g (0.34 mol); toluene: 100 ml.
After filtration of the isopropylamine hydrochloride and bromohydrate, the solvent is stripped and the residue is admixed with ~ 4 N HCl and the aqueous phase is washed with ether. The aqueous phase is treated with 50% aqueous NaOH, the amine is ether-extracted and, after drying on anhydrous Na2SO4, the ether is distilled and the residue is rectified in vacuum to obtain 14 g of the product. Yield = 50%.
The hydrochloride is crystallized by adding ethyl acetate to the base and then adding the necessary amount of pure alcohol saturated in dry HCl. Melting point 164°C.
