DE1670854B2 - PROCESS FOR THE PREPARATION OF 2,4,6-TRICHLOROPYRIMIDINES - Google Patents

Description

R — C — CN
R,

(D

in which R is a hydrogen or chlorine atom, an alkyl radical having 1-3 carbon atoms, which can be substituted by chlorine, bromine or fluorine atoms, or a phenyl radical which can be substituted by chlorine or bromine atoms or nitro groups, and Ri and R2 each mean a hydrogen or chlorine atom at temperatures of about 150-350 ⁰ C with trichloromethyl isocyanide dichloride of the formula II

Cl Cl

I /

Cl-C-N = C

Cl Cl

implements.

The starting components (I) and (U) are in approximately stoichiometric proportions or unreacted with one another with an excess of one or the other component

Nitriles of the formula (I) suitable for the process are, for. B. acetonitrile, chloroacetonitrile, dichloroacetonitrile, Trichloroacetonilril, propionitrile, p-chloropropionitrile, Butyronitrile, /J.y- dichlorobutyronitrile, benzyl cyanide, o-chlorobenzyl cyanide, p-bromobenzyl cyanide and o-nitro-ο benzyl cyanide.

Preference is given to using acetonitrile and trichloroacetonitrile, which are obtained in very good yields 2,4,6-trichloropyrimidine or 2,4,5,6-tetrachloropyrimidine is obtained

The process according to the invention is carried out in the presence or in the absence of inert solvents or diluents, at temperatures between about 150 and 350 ^° C., it being possible to work without pressure or under pressure and, if appropriate, in the gas phase. In general, it is advantageous to heat the starting components together in stoichiometric amounts, or to use a component as a solvent.

Hydrocarbons, chlorinated Hydrocarbons, e.g. B. methylene chloride, chloroform, carbon tetrachloride, chloroethanes, chloropropanes or one of the reaction components can be used.

The reaction can be promoted by acidic or basic catalysts.

The products of the process are known intermediates that can be used, for example, for the production of Reactive dyes are suitable.

Halopyrimidines are known from the literature. In the above-described process for their preparation the synthesis generally takes place over several stages, the last stage being a chlorination of the heterocyclic ring is carried out.

A process has now been established for the preparation of 2,4,6-trichloropyrimidines which may be substituted in the 5-position found, which is characterized in that a nitrile of the general formula 1

.15

R ₁

R — C — CN

R ₂

(D

in which R is a hydrogen or chlorine atom, an alkyl radical having 1-3 carbon atoms, which can be substituted by chlorine, bromine or fluorine atoms, or a phenyl radical which can be substituted by chlorine or bromine atoms or nitro groups, and Ri and R2 each mean a hydrogen or chlorine atom at temperatures of about 150-350 ⁰ C with trichloromethyl isocyanide dichloride of the formula II

Cl Cl

I /

Cl-C-N = C

I \

Cl Cl

fto

f'5

example 1

In a 0.3-liter enamel autoclave are heated for 5 hours at 25O ⁰ C 43 g Trichlormethylisocyanid dichloride and 8.2 g of acetonitrile in 100 ml of carbon tetrachloride. The reaction product is then filtered and the carbon tetrachloride is distilled off at normal pressure. then 2,4,6-trichloropyrimidine passes at 10 mm Hg between 89 ° C and 93 ⁰ C.

Yield: 30 g ~ 82% of theory. Mp. 21 ⁰ C.

Example 2

43 g of trichloromethyl isocyanide dichloride and 28.8 g of trichloroacetonitrile are ^{heated to 300 °} C. for 4 hours in a 0.3 liter VA autoclave. The oily tetrachloropyrimidine obtained is roughly distilled in a water jet vacuum and the distillate is recrystallized from methanol.

Yield 37.5 ~ 86% of theory. M.p. 67 ° C.

Example 3

43 g of trichloromethyl isocyanide dichloride and 17.5 g of chloroacetonitrile are heated in a 0.3-liter enamel autoclave for 4 hours at 25O ⁰ C. The oil obtained is then distilled in a water jet vacuum.

3Ig yield = 71% of theory tetrachloropyrimidine, mp. 67 ⁰ C.

Example 4

117g Benzyicyanid (1 mole) and 215g Trichlormethylisocyaniddichlorid (1 mol) are heated in a 0.7-1 autoclave for 3 hours at 19O ⁰ C. After cooling and releasing the pressure, a pulpy residue is obtained, which is recrystallized from ethanol after pressing.

Yield: 145 g of 2,4,6-trichloro-5-phenylpyrimidine 56% of theory. Th. Melting point: 159 ° C.

Example 5

In a 0.3-1-AutokIav 86 g Trichlormethylisocyaniddichlorid (0.4 MoI) and 27.6 g Buttersäurenitril be heated (0.4 MoI) for 4 hours at 190 ⁰ C. After cooling and letting down, fractional distillation is carried out. 44 g of 2,4,6-trichloro-5-ethylpyrimidine 52% of theory are obtained.

Boiling point: 116-120 ° C / l 2 bar, melting point: 72 ° C.

Claims (1)

Claim: Process for the preparation of 2,4,6-trichloropyrimidines optionally substituted in the 5-position, characterized in that a nitrile of the general formula I R ₁