Process for the preparation of o-substituted hydroxylamines

Details Process for the preparation of o-substituted hydroxylamines Process for the preparation of o-substituted hydroxylamines

C - Chemistry, Metallurgy

07

C

260/466.05, 260/

C07C 239/20 (2006.01) C07C 257/06 (2006.01) C07C 259/06 (2006.01)

Patent

CA 2035405

PS/5-l7917/= Process for the preparation of O-substituted hydroxylamines Abstract O-substituted hydroxylamines of the formula I H2NOR1 (I) in which R1 is C1-C6alkyl, C1-C6haloalkyl,-CH2CR2=CR3R4 or -CH2C=CR5; R2 is hydrogen, halogen or methyl; R3 is hydrogen, halogen or methyl; R4 is hydrogen, halogen or methyl; and R5 is hydrogen, methyl or ethyl, are prepared by reacting a nitrile of the formula II R6-CN (II) in which R6 is C1-C4alkyl, phenyl or benzyl, is reacted with an alcohol of the formula III R7-OH (III) in which R7 is C1-C5alkyl, benzyl or C1-C4alkoxyethyl, in an organic solvent which is only sparingly miscible with water or not at all, in the presence of hydrogen halide HX, the suspension obtained of the iminoester hydrohalide of the formula IV Image (IV) in which R6 and R7 are as defined above and X is chlorine, bromine or iodine, is added at a controlled rate to an aqueous suspension of a carbonate or hydrogen carbonate at a temperature of from -3 to +5°C, an aqueous solution of a hydroxylamine salt is added to the mixture obtained at a temperature of from -20 to -5°C, the aqueous phase is separated off after the mixture has been warmed to room temperature, the solution obtained of the hydroximic acid ester of the formula V Image (V) in which R6 and R7 are as defined above, in an organic solvent is first treated with an aqueous solution of a strong base and then with an alkylating agent of the formula VI Y-R1 (VI) in which R1 is as defined above and Y is chlorine, bromine, iodine or -O-SO2R8, and R8 is C1-C4alkyl, C1-C4haloalkyl, phenyl or phenyl-substituted C1-C4alkyl, it being possible for the phenyl ring itself to be monosubstituted, disubstituted or trisubstituted by halogen or C1-C4alkyl, and Y is alternatively -OSO2OR1 if R1 is C1-C2alkyl, at from room temperature to the boiling point of the reaction mixture, the mixture is cooled to room temperature when the O-alkylation is complete, the aqueous phase is separated off, the oxime ether of the formula VII Image (VII) in which R1, R6 and R7 are as defined above, formed is hydrolysed by stirring with an aqueous solution of a strong acid, and the aqueous phase containing the salt of the O-substituted hydroxylamine of the formula I is separated off, and the hydroxylamine of the formula I is isolated, if necessary, by evaporating the water.

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