DE2206506A1 - 2,6-dichloro-3,5-dicyano-pyridines - useful as inters for dyes and pharmaceuticals - Google Patents

Abstract

Cpds. of formula (I): (where X is H, opt. substd. alkyl, cycloalkyl, aralkyl or opt. substd. phenyl), are prepd. by reacting cpds. of formula (II) or their salts of formula (IIa): (where R is H or opt. substd. 1-8C alkyl and M circled positive is a cation) with POCl3 in the presence of a nitrogenous base.

Description

Process for the production of 2,6-dichloropyridine derivatives and new 2,6-dichloropyridines. Addition to patent. ....,. (Patent application P 21 27 521.8) Subject matter of the patent. .... ,, (patent application P 21 27 521.8) is a process for the preparation of compounds of the general formula in which R1 is hydrogen, alkyl with 1 to 8 carbon atoms, R2 is hydrogen, alkyl with 1 to 8 carbon atoms, phenyl optionally substituted by chlorine, bromine, methyl, ethyl, methoxy, ethoxy, cyano or nitro, carbalkoxy with a total of 2 to 5 carbon atoms or carbalkoxymethyl with a total of 3 to 6 carbon atoms and R3 denotes hydrogen or cyano, which is characterized in that compounds of the general formula in which R denotes hydrogen or an optionally substituted alkyl group having 1 to 8 carbon atoms and R1, R2 and R3 have the meaning given, is reacted with phosphorus oxychloride in the presence of a basic nitrogen compound.

It has now been found that compounds of the formula I can also be obtained very effectively by the process according to the invention or their salts of the formula Ia where X is hydrogen, optionally substituted alkyl, cycloalkyl, aralkyl or optionally substituted phenyl and K is a cation and R is as defined, compounds of the formula II receives.

In addition to hydrogen, radicals X are for example: methyl, Ethyl, n- or ieo-propyl or -butyl, n- or i-hexyl, octyl, -ethylpentyl, cyclohexyl, Phenyl, tolyl, methoxyphenyl or chlorophenyl. Preferred are alkyl radicals with approximately 3 to 8 carbon atoms and phenyl.

Ketions K are e.g. sodium or potassium and especially the proton or ammonium cations, such as ammonium, methylammonium, trimethylammonium, triethylammonium, Butylammonium or ß-hydroxyethylammonium.

The new 3,5-dicyanopyridine derivatives are valuable intermediates for dyes and pharmaceuticals.

Regarding procedural measures and further details apply the details of the main patent accordingly.

Example 1 44 parts of the ammonium salt of 2,6-dihydroxy-3,5-dicyano-4- (n) -propyl-pyridine are refluxed with 100 parts by volume of phosphorus oxychloride and 15 parts of triethylamine. Excess phosphorus oxychloride is then largely distilled off and the hot reaction mixture at 1200C is poured into 1000 parts of ice water with stirring. The precipitating, crystalline product of the formula is filtered off with suction, washed neutral with water and dried at 700C. About 40 parts of a colorless powder which melts at 95.degree. C. are obtained.

Example 2 38 parts of the ammonium salt of 2,6-dihydroxy-3,5-dicyan-4 methylpyridines are added to 80 parts by volume of phosphorus oxychloride at room temperature. 15 parts of triethylamine are then added dropwise and the mixture is heated for 6 hours Reflux cooling.

Phosphorus oxychloride is then distilled off until the temperature of the reaction mixture is about 160 to 1700 ° C., allowed to cool to 120 to 13000 ° C. and the mixture is poured into about 1000 parts of ice water with stirring. After stirring for one hour, the precipitated compound of the formula filtered off and washed neutral with water. After drying at 700C, about 38 parts of a colorless powder are obtained, which melts at 140 to 1430C.

Example 3 90 parts of 2,6-dihydroxy-3,5-dicyano-4-ethylpyridine become analogous to the procedure described in Example 1 with 170 parts by volume of phosphorus oxychloride and treated 40 parts of triethylamine.

After working up the reaction mixture - as described in the preceding example - about 80 parts of the product of the formula are obtained that melts at 12000.

Example 4 52 parts of the soap-like product of the formula are stirred with 130 parts by volume of phosphorus oxychloride and 15 parts of triethylamine for 8 hours under reflux cooling. Excess phosphorus oxychloride is then distilled off until the temperature of the reaction mixture is approximately 150 to 1700 ° C. and the mixture is stirred at this temperature for a further 10 hours. After cooling to about 1000 ° C., 500 parts of ice water are added to the residue. The mixture is stirred for 1 hour, cooled and extracted with chloroform. After washing and drying the extractant, the chloroform is distilled off. About 40 parts of a dark, viscous one remain as residue is equivalent to.

IR spectrum: 0-H 2850 cm strong -CrN 2210 cm -1 weak -C = C-, -C = N-hetero- 1520 cm 'very strong cyclus very strong 1350 cm -1 very Example 5 175 parts of the product of formula are refluxed for 5 hours with 350 parts by volume of phosphorus oxychloride and 60 parts of triethylamine. Excess phosphorus oxychloride is then distilled off until the temperature of the reaction mixture is 170 ° C. and the mixture is stirred at this temperature for 3 hours. After cooling to about 120 ° C., the mixture is poured into about 1000 parts of ice water with stirring. A greasy product is obtained. After the aqueous solution has been decanted off, the dark-colored, greasy residue is recrystallized from glacial acetic acid. After drying, about 120 parts of a colorless powder of the formula are obtained in this way which melts at 2450.

The pyridine derivatives of the formula listed in the table below can also be used analogously to the procedure described in Examples 1 to 6 produce: Example X 6 H. 7 -C3H7 (i) 8 -04H9 (n) 9 -C5H1 1 (n) 10 C5H11 (i) 11 -C7H.15 12 -CH-C4Hg (n) b, H 4 13th 14 CH3 15 y > D CH3 1 6 0-CH3 17 ¼0l 18 -CH2-CH24 19 D

Claims (2)

Claims 1. Modification of the process for the preparation of 2,6-dichloropyridine derivatives according to the patent. ... ... (patent application P 21 27 521.8) here characterized in that compounds of the formula or their salts of the formula Ia where X is hydrogen, optionally substituted alkyl, cycloalkyl, aralkyl or optionally substituted phenyl and K @ is a cation and R is hydrogen or an optionally substituted alkyl group having 1 to 8 carbon atoms, compounds of the formula II manufactures. 2. Compounds of the formula in which X is optionally substituted alkyl, cycloalkyl, aralkyl or optionally substituted phenyl.