SU145582A1 - Laboratory method of obtaining radioactive nicotinic acid (vitamin PP) - Google Patents

Description

The invention relates to laboratory methods for the production of nicotinic acid (vitamin PP) with a labeled carbon atom in the carboxyl group.

The known methods, consisting in the condensation of 3-bromopyridine with n-butyl lithium and the subsequent carboxylation of carbon dioxide with a labeled carbon atom, are not very convenient, since they provide for the application of high vacuum, strong cooling of the reaction mixture and rather complicated apparatus.

According to the proposed method, in order to simplify the process, the interaction of radioactive copper cyanide with 3-iodopyridine produces radioactive 3-cyanniridine, which is converted into radioactive nicotinic acid by known methods. The specified synthesis can be expressed by the following scheme:

I,

 f IP 2H

The starting 3-iodopyridine can be obtained in a known manner from 3-aminopyridine using a diazotization reaction. Cyanic copper with a radioactive carbon atom can be obtained from radioactive potassium cyanide or sodium by reaction with copper sulfate in the presence of potassium bisulfite by the reaction:

2CuSO4 + + KHSO3 + H2O - 2 + 3 KHSO4.

Example 1- To a solution of 14.5 g of copper sulfate in 46 ml of water at a temperature of 60 ° and moving, a solution of 5.2 g of potassium metabisulfite in 12 ml of water is poured, and then a solution of 1.035 g of CS N (specific activity of 48.3 μyr1g) and 2.96 g of inactive potassium cyanide in 12 ml of water. After 10 minutes of exposure, the reaction mass of 145582-2 is heated to a temperature of 60-70 ° and filtered. The precipitate of copper cyanide is washed with boiling water (5 times 25 ml), then 10 ml of alcohol and dried at a temperature of 70-80 °. 3.25 g of copper cyanide are obtained in the form of a light gray powder with a specific activity of 10 mcury / g. Yield (based on initial cyanide potassium): chemical-61.5%; radiochemical-65, 0%.

Example 2. In a flask equipped with a reverse air cooler, a Mixture of 10.0 g of 3-iodopyridine and 3.0 g of dry cyanide l is prevented: one with a specific activity of 5.35 μyr1g. The flask is heated on a metal bath at a temperature of 235 ° for 45 minutes. Then in vacuum at a residual pressure of 10-15 mm Hg. Art. the volatile products are frozen, frozen in the receiver. The obtained distillate, in which 3-cyanopyridine is found, is dissolved in 30 ml of 70% ethanol, 3.0 g of sodium hydroxide is added and boiled for 3 hours. The solvent is then distilled off, and the residue is dissolved in 10 ml of water, decolorized with charcoal and acidified with hydrochloric acid until neutral. The resulting solution is evaporated to 8-10 ml, cooled, acidified to pH 3.5 and, after 10 hours at a temperature of 2 °, the precipitated nicotinic acid is filtered off. After recrystallization from hot water, 1.24 g of pure nicotinic acid (about 99%) with healthy activity of 3.8 mcuri / g are obtained. Output (counting on initial cyanic copper): chemical-29.8%; radiochemical-29, 7%.

The proposed method is simple, gives a sufficiently high yield of the target product, and can be successfully applied for the preparative preparation of radioactive nicotinic acid.

Subject invention

A laboratory method for producing radioactive nicotinic acid (vitamin PP), characterized in that, in order to simplify the process, the interaction of radioactive copper cyanide with 3-iodopyridine produces radioactive 3-cyanopyridine, which is converted into radioactive nicotinic acid by known methods.