Preparation method of caffeine intermediate N,N-1,3-dimethyl-4,5-diamido urazine

Abstract

The invention relates to a preparation method of the caffeine intermediate N,N-1,3-dimethyl-4,5-diamido urazine and belongs to the technical field of synthesis and preparation of organic compounds. According to the preparation method, a hydrogen addition reaction is carried out under heated and pressurized conditions with N,N-1,3-dimethyl-4-imido-5-isonitroso urazine as the starting material and raney nickel as the catalyst, an aqueous solution containing metal halide and alkaline substances is used as the reaction medium, the preparation method has the advantages of being smooth and controllable in reaction, high in catalytic activity and stable in quality of dimethyl-DAU, and the yield and the quality of the dimethyl-DAU are improved.

Description

technical field [0001] The invention relates to a preparation method of a caffeine intermediate, in particular to a preparation method of a caffeine intermediate N,N-1,3-dimethyl-4,5-diaminocarbazine, and belongs to the technical field of synthesis and preparation of organic compounds . Background technique [0002] Caffeine, a xanthine drug, has excitatory and diuretic effects on the heart and brain nerves, and is widely used clinically. N,N-1,3-Dimethyl-4,5-diaminocarbazine (dimethyl-DAU) is an important intermediate in the synthesis of caffeine. At present, it is composed of N,N-1,3- Dimethyl-4-imino-5-isonitrosourazine (dimethyl-NAU) is obtained through reduction reaction. Among them, the reduction reaction methods mainly include iron powder plus sodium chloride reduction, catalytic hydrogenation reduction and electrochemical reduction. The iron powder reduction reaction will produce a large amount of iron sludge, which will have a bad impact on the environment; elect...

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Problems solved by technology

Based on the above-mentioned distinguishing technical features, the technical problem solved by the Chinese patent document CN1017241B is to overcome the instability of dimethyl DAU caused by the use of alkaline solution in the British patent document GB2001310. However, the Chinese patent document CN1017241B records the use of neutral The water is used as the reaction medium, and the dimethyl DAU is formylated with formic acid immediately after the reaction. The additional step of the formic acid formylation of the dimethyl DAU is because the dimethyl DAU is still unstable and is stabilized by formic acid formylation. form, or just to prepare the target product, the Chinese patent literature does not indicate, and there is no corresponding record in its examples, but from the expression of "formylation of dimethyl DAU with formic acid immediately after the reaction", it reflects that The urgency of time also shows that the problem of instability of dimethyl DAU in the reaction system of Chinese patent document CN1017241B still exists. In addition, dimethyl NAU is poorly soluble in water, which is not conducive to the reaction, and Raney nickel is in The catalytic selectivity in water is not good, and the excitation reaction is too fast, so that the reaction generates some by-products, resulting in a low yield of dimethyl DAU, and the quality of finished products such as crude theophylline and crude caffeine is relatively poor, and secondary refining is required. Meet the quality requirements of qualified products

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