Method for synthesizing lecdopamine

The present invention relates to a method for synthesizing ractopamine hydrochloride by using p-hydroxyacetophenone and raspberry ketone as raw materials. The p-hydroxyacetophenone is processed by catalytic brominating reaction to obtain omega-bromo-p-hydroxyacetophenone. The raspberry ketone is processed by oximation and catalytic hydrogenation to obtain 1-methyl-3-(4-hydroxyphenyl)-propylamine.The omega-bromo-p-hydroxyacetophenone and 1-methyl-3-(4-hydroxyphenyl)-propylamine are added in two-phase system formed from alkaline aqueous solution and ethyl acetate ,strenuously stirred and reacted, then the obtained reaction product is acidified by hydrochloric acid to obtain intermediate product hydrochloride of 1-(4-hydrophenyl)-2-£1-methyl-3-(4-hydrophenyl)-propyl|-ethylketone, then said intermediate product is processed by catalytic hydrogenation reduction so as to obtain the invented product ractopamine hydrochloride.