DE1670961A1 - Process for the production of tetrachloropyrimidine - Google Patents

Description

Process for the preparation of tetrachloropyrimidine It has been found da # 2, 4, 5, 6-tetrachloropyrimidine from mono-, di- or trichloropyrimidines or mixtures such partially chlorinated pyrimidines in high yield without the formation of by-products can be obtained if gaseous partially chlorinated pyrimidine together with excess chlorine at temperatures of about 350 to 650 ° C, preferably 400 to 500 ° C, heated in a Strosungsrohr.

The reaction is advantageously carried out in such a way that the gaseous partially chlorinated pyrimidine together with excess chlorine at the specified Temperatures in the Stros. connection tube via a contact, for example quartz shards, conducts, which can also be a catalyst or has catalyst properties, for example a nickel catalyst in the form of nickel rings, copper chloride (CuCl2) a support, such as on pumice stone, ferric chloride (FeCl3) on a.

Carrier, such as on silica gel, or activated carbon.

The partially chlorinated phrimidines used in the present processes are predominantly literate; They can also be made more suitable by means of a ring closure nitrogenous aliphatic compounds, partly under chlorinating conditions, manufactured will. For example, 4, 5-dichloro and 4,5,6-trichloropyrimidine by treating dimethylaminopropionitrile at temperatures from 0-250 ° C with excess chlorine under UV irradiation and under the same conditions 2, X, 5-trichloropyrimidine from N-methyl-N-chlorocarbonyl-3-aminopropionitrile.

These and other partially chlorinated pyrimidines, such as 2, 4, 6-trichloropyrimidine, 2,4-dichloro-6-methylpyrimidine and 2-t: ethyl-4, 6-dichloropyrimidine are available as such or in any combination with one another equally well in the new process to use. Of course, you can also use mixtures of partially chlorinated pyrinidines, z. B. 2, 4, 6-trichloropyrimidine, use with tetrachloropyrimidine.

Such mixtures occur in other modes of representation for tetrachloropyrimidine and can be made easier and more cost-saving by the method according to the invention Working method, d. H. without the otherwise necessary separation of partially chlorinated pyrimidines, Convert into pure 2, 4, 5, 6-tetrachloropyrimidine.

Compared to chlorination in the liquid phase, there is a special one The advantage of the new process is that by-products, such as those in the production of 4, 5, 6-trichloropyrimidine, such as trichloromiethyl isocyanide dichloride, are destroyed in the gas phase chlorination according to the invention (training carbon tetrachloride) so that # it is not necessary to use pre-cleaned products to be used for chlorination.

The reaction rate of the chlorination in the gas phase depends when using contacts located in the flow tube of the type of KontaMe away. As usual with reactions of this kind, have-diverse Contacts different influence on reaction speed; for the present This is mainly done with the following overview for individual contacts Catalysts, explained: Contact Temperature Gram / Ltr. Contact, h nickel rings 465 ° C 71 Quartz shards 440 ° C 45 5% CuCl2 on pimestone 440 ° C 100 10% CuCl2 on Pumice stone 440 ° C 130 3% FeCl3 on silica gel 470 ° C 33 Activated charcoal, granulated 460 ° C 1815 When using activated carbon, a greater throughput of the gaseous reactants is required good heat dissipation of the exothermic reaction. It is therefore for In these cases the purpose of the reaction is to take place in upright tubes running through a u::. running gas or kept at a constant temperature by a bath liquid be allowed to run off or the reaction mixture by adding a in the circuit led gas, such as nitrogen or hydrogen chloride to dilute. Furthermore can the starting product can be diluted with tetrachloropyrimidine, so that the reaction mixture can absorb part of the heat of reaction.

The term flow tube in the sense of the present is very general Invention broadly understood. This includes Pipes and tubular reaction devices of various arrangements, be it straight, curved, meandering or spirally arranged through which the gaseous reactants can flow at greater or lesser speed. Also fluidized bed type Arrangements of reaction spaces are intended to fall under this within the meaning of the invention. The flow tubes can also contain various types of internals, such as baffles, Raschig rings and cooling tubes, which are advantageous for the desired course of the reaction could be. The flow rate with which the gaseous reactants are passed through the flow pipe, can be designed variably and depends among other things of the used material of the flow tube, the temperature and the desired throughput speed. As mentioned, can respondents an inert gas can also be added for the purpose of dilution.

The gaseous starting products are expediently in one such a quantitative ratio that chlorine is in an: excess of at least 50%, advantageously 100%, over the theoretically required amount. Larger excesses are not disadvantageous for the course of the reaction.

With a smaller excess of chlorine, the completeness of the Chlorination reaction.

The implementation according to the process leads to excellent yields and can be carried out equally well when using different contacts. The reaction product is when using a corresponding excess of gaseous chlorine is pure tetrachloropyrimidine, in which some chlorine is dissolved. By subsequent degassing, e.g. B. in a Hieselkolorme while sliding against by inert gas, such as carbon dioxide or nitrogen, or by brief heating, if necessary under reduced pressure, in an evaporator of any type, becomes one of chlorine obtained free tetrachloropyrimidine with a melting point of 67-68 ° C, which was not detectable Has impurities.

In the following examples, the temperature data are degrees Celsius.

Example 1: A vertical tube made of quartz material of 300 mm Long and 30 mm in diameter, that of a highly thermally conductive, heatable and coolable Metal cylinder is surrounded and that with the necessary supply lines for chlorine, chloropyrimidine as well as with a template. is provided with dry activated carbon with a diameter of 3 mm filled. At 400 °, a metering pump uryd makes a gas control valve a more even Flow of 390 g / h of 4,5,6-trichloropyrimidine and 300 g / h of chlorine over the catalyst bed directed. The temperature m m catalyst rises to 500 ° and is cooled by cooling of the metal cylinder is kept at this temperature. The catalyst is at 80 - 100 ° collected, the exhaust gas is passed through a reflux cooler maintained at 20 and there separating solid tetrachloropyrimidine from time melted out at time and added to the reaction product obtained. After degassing at 20 Torr and 100 ° the reaction product is chlorine-free and is pure at 67-68 ° melting tetrachloropyrimidine. The yield is 610 g of tetrachloropyrimidine / h. M.p. 67-68 °.

In the same apparatus as described in this example, is at 450 ° C a stream of 65 g / h 2, 4-dichloro-6-methylpyrimidine and 213 g / h chlorine over passed the catalyst bed. 70 g / h of pure tetrachloropyrioidine are obtained.

In the apparatus described in this example, the temperature is 450.degree a flow of 65 g / h of 2-methyl-4,6-dichloropyrimidine and 213 g / h of chlorine over the catalyst bed directed. 77 g / h of pure tetrachloropyrinidine are obtained.

Example 2: In the same apparatus as described in Example 1 a stream of 390 g / h of 2,4,6-trichloropyrimidine and 300 g / h of chlorine is passed over at 450 ° passed the catalyst bed. 610 g / h of pure tetrachloropyritnidine are formed.

Example 3: In the same apparatus as described in Example 1 a stream of 390 g / h of 2,4,5-trichloropyrimidine and 300 g / h of chlorine is passed over at 450 ° passed the catalyst bed. 610 g / h of pure tetrachloropyrimidine are formed.

Example 4: In the same apparatus as described in Example 1 a stream of 230 g / h of 2,4-dichloropyrimidine and 330 g / h of chlorine is over the catalyst bed directed. The oven, heated to 400 °, must be strongly cooled so that it can adjusts the temperature in the catalyst bed to approx. 480 °. There are 337 g / h of tetrachloropyrimidine educated.

Example 5: In the apparatus described in Example 1, a Mixture of 79% 2, 4, 5, 6-tetrachloropyrimidine, 11% 4,5,6-trichloropyrimidine and 10% impurities such as trichloromethyl isocyanide dichloride, pentachloroethyl isocyanide dichloride and resin of unknown composition. Such a mixture as it is at the synthesis of 4, 5, 6-trichloropyrimidine is obtained at a rate 100 g of chlorine / h of 400 g / h of assurances cit passed over the activated charcoal bed at 480 °. A mixture of tetrachloropyimidine and carbon tetrachloride is used as the catalyst obtained that easily worked up to pure tetrachloropyrinidine by distillation can be. The yield is 168% per hour of pure tetrachloropyriridine.

Claims (4)

Claims: 1. Process for the production of 2, 4, 5, 6-tetrachloropyrimidine, characterized in that gaseous mono-, di- or trichloropyrimidines or Mixtures of such partially chlorinated pyrimidines with excess chlorine at temperatures from about 350 to 650 ° C, preferably 400 to 50 ° C "heated in a flow tube. 2. The method according to claim 1, characterized in that # one the gaseous reactants in a flow tube via contacts that passes Catalysts can be. 3. The method according to claim 1, characterized in that # one the gaseous reactants in a flow tube over dry shaped activated carbon directs. 4. 4, 5,6-tetrachloropyrimidine, obtained by the process of claims 1 to 3.