Study On Synthesis Of 3-Methoxy-N-phenyl-benzenamine

3-Methoxy-N-phenyl-benzenamine is an important intermediate for producing negative PS photosensitizer,2-methoxylphenothiazine and fluorane heat sensitive dyes,and is widely used in medicine,dye and printing industry.3-Methoxy-N-phenyl-benzenamine was synthesized from the methoxylation of m-dinitrobenzene,followed by reduction,N-acylation,Ullmann condensation and hydrolysis. The overall yield was 70.2%.In the methoxylation of m-dinitrobenzene,methanol was used as solvent instead of the toxicant,expensive and polar ones.The optimized conditions were:the mole ratio of m-dinitrobenzene and sodium methoxide of 1:1.2,the 0.2%wt 18-crown-6-ether as the phase transfer catalyst to m-dinitrobenzene,reaction temperature of 120℃,reaction pressure of 0.65MPa,reaction time of 6h.With these conditions,the product was obtained with a yield of 89.9%.3-Methoxy-benzenamine was synthesized through the hydrogenation of m-nitroanisole obtained with palladium on carbon(10%wt)as catalyst in methanol solvent.Under the optimized conditions of:0.5%wt of catalyst to m-nitroanisole,reaction temperature of 80℃, pressure of 2.0MPa,reaction time of 8h,the yield for 3-methoxy-benzenamine was 93.5%.The catalyst can be reused for five times without big lose of the hydrogenation yield,i.e.addition 20%wt of the new catalyst after every reaction.The solvent can be used indiscriminately.Triphosgene was used as the acylating agent of 3-methoxy-benzenamine in N-acylation to obtain 3,3'-dimethoxy-diphenyl urea which could reacted with chlorobenzene under the mild conditions.At the same time,there was not water produced in N-acylation,so it could avoid the hydrolysis reaction in the Ullmann condensation.Under the optimized conditions,4 fold moles of 3-methoxy-benzenamine to triphosgene,4.0%wt of triethylamine to 3-methoxy-benzenamine as catalyst,reaction temperature of 30℃,reaction time of 7h,the yield of 92.7%for the objective product was obtained.In Ullmann condensation,the coupled compound of iodide copper and N,N'-dimethyl ethylene diamine was employed as the catalyst and potassium carbonate as acid-reacted agent. The effects of various factors were investigated.The optimized conditions were:the mole ratio of chlorobenzene and 3,3'-dimethoxy-carbanilide was 3.0:1,the excess chlorobenzene was recovered by steam distillation after the condensation reaction,reaction temperature of 130℃, the 0.2%wt iodide copper and 2.0%N,N'-dimethyl ethylene diamine to 3,3'-dimethoxy-carbanilide,the mole ratio of potassium carbonate and 3,3'-dimethoxy-carbanilide was 2.2:1,reaction time of 4h.With the conditions above,the conversion of 3,3'-dimethoxy-carbanilide was 98.7%.The solution of sodium hydrate was directly used for hydrolysis.With the mole ratio of sodium hydrate and 3,3'-dimethoxy-carbanilide was 2.5:1,reaction time of 5h,the yield was 90.9%.The structure of the product and the relative intermediates were confirmed with the melting point,GC-MS,ESI-MS,IR,H-NMR.The paper successfully got a new route for the synthesis of 3-methoxy-N-phenyl-benzenamine characterized by cheaper and more readily obtainable raw materials,more convenient operation and less pollution.