RU2269536C1 - Method for preparing tetrapyrazinoporphyrazine - Google Patents

Abstract

FIELD: organic chemistry, chemical technology.

SUBSTANCE: invention relates to the improved method for preparing tetrapyrazinoporphyrazine. Method involves heating up of 2,3-dicyanopyrazine with compound of alkaline metal and the following acid demetallization of formed product. As compound of alkaline metal the method involves using dry sodium hydroxide and heating up is carried out to temperature 200-220°C and formed melt is kept at this temperature for 10-15 min. Method provides simultaneous significant simplifying and decreasing cost of the method for preparing tetrapyrazinoporphyrazine by diminishing number of technological stages by two times and to enhance the yield of the end product by 1.2-fold.

EFFECT: improved preparing method.

2 cl, 1 tbl, 1 ex

Description

Introduction

The invention relates to the chemical industry, and in particular to methods for producing tetrapyrrole macroheterocyclic compounds - tetraarenoporphyrazines, i.e. porphyrazines linearly annelated by aromatic or heteroaromatic rings containing various substituents, specifically, to a method for producing tetrapyrazinoporphyrazine.

State of the art

Tetrapyrrole macroheterocycles play an important role in wildlife and technology, entering the structure of respiratory pigments, enzymes, vitamins, catalysts, sensors, semiconductors, etc.

The preparation of metal-free tetraarenoporphyrazines usually involves the template synthesis of the labile metal complex of tetraarenoporphyrazine with magnesium or its sodium or lithium salts from aromatic o-dinitrile with subsequent demetallization and always presents certain difficulties. These include the instability of ligands under the conditions of demetallization of magnesium complexes and poor reproducibility and low yields upon receipt of lithium or sodium salts.

Known methods for producing tetrapyrazinoporphyrazine, which consist in the synthesis of a magnesium complex of tetrapyrazinoporphyrazine from 2,3-dicyanpyrazine and a magnesium salt and its subsequent demetallization or washing with dilute acid (yield 72%) (Linstead, RP; Noble, EG; Wright, JMJ Chem. Soc. 193737 , 921) or reprecipitation from a solution in concentrated sulfuric acid by pouring onto ice (80% yield) (Berezin B.D., Klyuev V.N., Korzhenevsky A.B. Izv. VUZ. Chemistry and chemical engineering. 1977, T .20, issue 2, P.171).

The disadvantage of these methods is the duration and multi-stage.

Closest to the claimed is a method of producing tetrapyrazinoporphyrazine (Lukyanets E.A. Doctoral dissertation, Moscow, 1977, p. 251-252), which consists in adding 2,3- to a solution of lithium amylate in absolute amyl alcohol with stirring dicyanpyrazine. The mixture is boiled for 1 hour and evaporated to dryness in vacuo. Then, the resulting product is demetallized by reprecipitation from concentrated sulfuric acid by pouring onto ice. The precipitate is filtered off, washed with water and dried.

The disadvantages of this method are the complexity, high cost of the reagents used and the insufficiently high yield of the target product. The complexity is due to the multi-stage 13 technological operations, taking into account the preparation of lithium amylate and the absolute amyl alcohol; the complexity of preparing lithium amylate, absolute amyl alcohol, evaporating the reaction mixture in vacuo, dissolving the resulting product in concentrated sulfuric acid, filtering a fine suspension of the product formed by reprecipitation on ice; the duration of absolute amyl alcohol, dissolving the resulting product in concentrated sulfuric acid, filtering a fine suspension of the product; using special precautions when working with anhydrous media and reagents (lithium amylate, absolute amyl alcohol and sulfuric acid). The yield of the target product is 80%.

SUMMARY OF THE INVENTION

The objective of the invention is to find a method for producing tetrapyrazinoporphyrazine by heating 2,3-dicyanpyrazine with an alkali metal compound and subsequent acid demetallization of the resulting product, which would be simplicity, using cheap reagents and higher yield of the target product.

The problem is solved by the method of producing tetrapyrazinoporphyrazine by heating 2,3-dicyanpyrazine with an alkali metal compound and subsequent acid demetallization of the formed product, in which dry sodium hydroxide is used as an alkali metal compound, heating is carried out to a temperature of 200 ÷ 220 ° C and the resulting melt is maintained at this temperature for 10 ÷ 15 minutes.

Distinctive features of the method are the use of dry sodium hydroxide as an alkali metal compound, heating to a temperature of 200 ÷ 220 ° C and, prior to demetallization, maintaining the formed melt at this temperature for 10 ÷ 15 minutes.

These distinguishing features for the preparation of tetrapyrazinoporphyrazine are not known.

The invention allows to significantly simplify and reduce the cost of the method of producing tetrapyrazinoporphyrazine and increase the yield of the target product.

The simplification of the method is achieved by reducing multi-stage from 13 stages, taking into account the preparation of lithium amylate and the absolute amyl alcohol, up to 6; elimination of time-consuming operations such as preparation of lithium amylate, absolute amyl alcohol, evaporation of the reaction mixture in vacuo, dissolving the resulting product in concentrated sulfuric acid, filtering a fine suspension of the product formed during reprecipitation on ice; elimination of the most lengthy operations - absolute amyl alcohol, dissolving the resulting product in concentrated sulfuric acid, filtering a fine suspension of the product; elimination of anhydrous media and reagents (lithium amylate, absolute amyl alcohol and sulfuric acid) that require special precautions when working.

Cheaper costs are achieved by replacing expensive reagents of amyl alcohol and lithium amylate with cheap sodium hydroxide.

The yield of the target product rises to 97%.

In addition, the method can dramatically increase the reproducibility of the results.

Information confirming the possibility of carrying out the invention

For the implementation of the invention, the following substances are used: 2,3-dicyanpyrazine obtained by the method (Halpern E.G., Lukyanets E.A. Zh.V.Kh.O.D. Mendeleev, 1967, T.12, No. 4, S.474 ) and sodium hydroxide grade "GC" GOST 4328-77.

To obtain tetrapyrazinoporphyrazine, 1 g (7.6 mmol) of 2,3-dicyanpyrazine is mixed with 1 g of dry sodium hydroxide, heated to a temperature of 200 ÷ 220 ° C and the resulting melt is maintained at this temperature for 10-15 minutes. Then the reaction mixture is cooled, washed with distilled water and the precipitate is filtered off. The resulting product is subjected to acid demetallization, for example, by successive washing on the filter with distilled water until the filtrate is neutral, then slowly 50 ml of 10 ÷ 35% hydrochloric acid and again with water until the filtrate is neutral, or reprecipitation from concentrated sulfuric, phosphoric or trifluoroacetic acids .

Received tetrapyrazinoporphyrazine in the form of a bright blue fine crystalline substance.

The target product can be purified by known methods.

The product was identified by the elemental composition and electronic absorption spectrum of the solution in dimethyl sulfoxide.

The yield of the target product during the implementation of the method using various temperatures and holding times is shown in the table

Table. The yield of the target product Holding temperature, ° С Holding time, min Product yield,% 200 10 95 210 10 95 220 fifteen 96 220 fifteen 97

Claims (1)

A method of producing tetrapyrazinoporphyrazine by heating 2,3-dicyanpyrazine with an alkali metal compound and subsequent acid demetallization of the resulting product, characterized in that dry sodium hydroxide is used as an alkali metal compound, heating is carried out to a temperature of 200 ÷ 220 ° C and the resulting melt is maintained at this temperature within 10 ÷ 15 minutes