Dl-tryptophan Synthesis Process

Tryptophan is one of the essential amino acids in living bodies, which is a indispensable substance. If lacking it in bodies, other nutriment will not be in good absorbed. It plays important roles in the fields of feeds as well as medicine, In the same time, owing to the requirement of DL-tryptophan in the animal feeds additive reach one million ton per year, while, at present, the production is only one thousand ton per year. So many researchers pay attention to apply tryptophan to this field. Therefore, It is a necessary for us to exploit an economical way to the synthesis process of DL-tryptophan.At present, owing to tryptophan is very expensive, only a little of it applied to animal feed additive field. In this papers, attempt to research a cheaper synthesis process with a good use of abundant coal tar in northeast and apply coking indole to prepare the intermediate of tryptophan: 3-(dimethylaminomethyl)indole, general name is gramine.Gramine condension with diethyl aminomethyl to prepare the condensation compound and through the reaction of hydrolysis to obtain the qualified product of tryptophan.The synthesis process of gramme: dimethylamine was reaction with HC1 under low temperature until PH5.5-6.5.adding HCHO, catalyst and indole were added below 10C. After 0.5hr, up to 20C slowly. Reaction time 6hr.adding 20%NaOH solution to PH10.the product of deposit through filtrate and wash with water to PH 8 when the filter cake was dried, obtain the product of gramine. The purity surpass 94% and the yield reach 90% for indole .Because of add catalyst, reduce the polymerization of indole. For make use of inorganic acid and coking indole, the cost of the production reduce effectively, and so on the tryptophan.Diethyl acetamidomalonate was made from diethyl malonate. Through nitrosation, hydrogenate reducion, and acylate three steps, the yield surpass 80% for the diethyl malonate.Under the alkali conditions, the gramine condension with diethyl acetamidomalonate to obtain the condensation compound. DL-tryptophan could be synthesized from condensation compound by the reaction of hydrolysis using water. The total yield could reach 69% for indole.In this processing, make good use of important resources in coal tar. The production cost of DL-tryptophan reduced effectively. So it is a good chance for tryptophan use widely.