A New Process For Preparing O-alkyl Hydroxylamine

O-alkyl hydroxylamine is a widely applied intermediate in organic synthesis,especially can be used as raw materials for preparing herbicides of 3-hydroxycyclohex-2-enones and drugs of cephalosporin.In this thesis,two synthetic processes for o-alkyl hydroxylamine were studied and compared including the method of sulfuric acid ester and halogenated hydrocarbon.Both of these methods were improved and optimized,and the better parameters were obtained.The process of the method of sulfuric acid ester was as follow:Firstly,butanone oxime was prepared from butanone with hydroxylamine hydrochloride,butanone oxime was treated with sulfuric acid ester to get o-alkyl butanone oxime,the o-alkyl hydroxylamine was prepared by hydrolysis of o-alkyl butanone oxime using hydrochloric acid and neutralization.The optimized conditions were:The molar ratio of butanone and hydroxylamine hydrochloride was 1:1.2,the catalyst were 1%tetrabutylammonium bromide and 10%sodium carbonate(the molar ratio of butanone),the pH was adjusted to 6 at ice bath,then it reacted at 55-60℃ for 1h.The yield of butanone oxime was 90.1%,and the purity was 99%.Secondly,the molar ratio of butanone oxime and diethyl sulfate was 1:1.3,it reacted at 20℃ for 8h with 9-9.3 pH after diethyl sulfate was added at 5℃,the yield and purity of o-ethyl butanone oxime were 92.4%and 99%respectively.Lastly,o-ethyl butanone oxime was hydrolyzed by hydrochloric acid at 80 ℃ for 3 hours,and the molar ratio was 1:1.2.The yield and purity of o-ethyl hydroxylamine were.86.2%and 98%.The method of halogenated hydrocarbon,which was different from the method of sulfuric acid ester,was used halogenated hydrocarbon instead of sulfuric acid ester during preparing o-alkyl butanone oxime.The optimized conditions of halogenated hydrocarbon were:The molar ratio of butanone oxime and bromoethane was 1:1.3,bromoethane was added dropwise at 20℃,then it reacted for 6 hours with 9-9.3 pH.The yield and purity of o-ethyl butanone oxime were 86.2%and 99%.We also synthesized o-methyl hydroxylamine by using the method of sulfuric acid ester,and prepared further o-alkyl hydroxylamine such as o-propyl hydroxylamine,o-isopropyl hydroxylamine,o-allyl hydro-xylamine and o-benzyl hydroxylamine by the method of halogenated hydrocarbon on the same condition.Although the method of sulfuric acid ester had the disadvantage of high toxicity and heavy pollution,it was also widely used in industry with low raw material cost and high yield.The method of halogenated hydrocarbon had the shortcomings of high raw material cost and low yield,but the advantage of little pollution,low toxicity and easy to separate mad it has a bright future for application.