DK159682B - METHOD FOR PREPARING N, N-DIMETHYLPIPERIDINIUM CHLORIDE OR N, N-DIMETHYLMORPHOLINIUM CHLORIDE - Google Patents

Description

DK 159682 B

The invention relates to a particular process for the preparation of N, N-dimethylpiperidinium chloride or N, N-dimethylmorpholinium chloride from the corresponding mono-methyl compounds and methyl chloride in the presence of water.

The method according to the invention is characterized by the 5 of the characterizing part of claim 1.

It is known to use N, N-dimethylpiperidinium chloride or N, N-dimethylmorpholinium chloride as an agent for influencing plant growth (DE Patent No. 1 642 215 10 and DE Publication No. 2 207 575). They are used in the form of an aqueous solution of the active substances. The preparation of the active substances N, N-dimethylmorpholinium chloride or N, N-dimethylpiperidinium chloride takes place in a known manner by transferring N, N-15 dimethylpiperidinium iodide or N, N-dimethylmorpholinium iodide to the corresponding chlorides (Helv. Chim. Acta 39, 399 (1956) or Chem., Ber. 22, 2091 (1889)).

It has now been found that N, N-dimethylpiperidinium chloride or N, N-dimethylmorpholinium chloride from N-methylpiperidine or N-methylmorpholine can be readily and in excellent yield when reacting N-methylpiperidine or N-methylmorpholine with methyl chloride. presence of water as diluent at a temperature of from 0 to 25 100 ° C and a pressure of from 1 to 7 bar.,

This is surprising and could not be foreseen because methylations with methyl chloride have heretofore either been carried out in non-aqueous solvents or where, when using water as a diluent, temperatures (above 80 ° C, preferably above 100 ° C) have to be used. typically a temperature of 155 ° C) which is well above room temperature and high pressures, cf. DE Patent No. 756 185, page 2, lines 38-39 and 61 and line 113.

35 2

DK 159682 B

It is admittedly known from DE patent specification 756 185 a method of using water as a solvent to form quaternary ammonium chlorides from tertiary amines and alkyl halides having at least 85 carbon atoms. In the examples, C 8 to C 12 alkyl chloride reactions are indicated. In contrast, the reactions of the invention are carried out with methyl chloride. By the reaction of alkyl chlorides in water, there is a risk of these being hydrolyzed to alcohols and thus no more 10 available for the reaction. The tendency for hydrolysis is the greater the more soluble in water the alkyl chlorides are. Long chain alkyl chlorides (over 7 carbon atoms) are more soluble in water than methyl chloride.

Therefore, it was to be expected that reactions with C 8 alkyl-15 chlorides could not be converted to methyl chloride because of the risk of methyl chloride being hydrolyzed.

Even more surprising, therefore, is that the method of the invention with methyl chloride provides end products in good yield and high purity.

20

It is admittedly also known from U.S. Patent No. 3,567,729 to a process for the preparation of quaternary ammonium salts which comprises reacting tertiary amines with 1-halo-2-hydroxy-3-alk-oxy-propanes in the presence of water. . The corresponding epoxy compounds can be used instead of these halides, cf. column 4, lines 59-66. It is known that l-halogen-2-hydroxy compounds are not readily converted to the corresponding epoxy compounds in alkaline solution. Thus, the known reactions are specific reactions carried out with specific halides, whereby, as intermediates, epoxy compounds may be present. Water is needed to carry out the reactions. However, very specific alkyl halides have to be used for the known reaction and these are very different from the methyl chloride used in the process of the invention with regard to the chemical structure. In particular, these are 3

DK 159682 B

capable of substituting, for example, intermediate alkyl halides under the reaction conditions to form epoxy compounds likely to be intermediates in the reaction. This means that the known reaction is of a type which is in principle different from the type of reaction to which the process according to the invention belongs. Thus, the fact that water is necessary to carry out the known reaction can in no way justify the conclusion that water should also be necessary in the process of the invention.

The process according to the invention has two main advantages: firstly, the process due to the use of water as a diluent is very simple and therefore very economical, because the aqueous solution of the final products can be used directly for biological application, namely to influence plant growth. Secondly, under normal pressure or slightly elevated circulation, the use of inexpensive, serially 20 stirred vessels can be used because, for safety reasons, these are usually sized for a pressure of from 4 to 7 bar for safety reasons.

The reaction may, in the case of N-methyl-piperidine, be represented by the following reaction scheme: N - CH 3 + CH 2 Cl -? In comparison with known methods, the process of the invention produces in a simple and economical manner.

DK 159682 B

4 the desired quaternary ammonium chlorides in good yield and high purity. While they previously stated from Helv. Chim. Acta 39, 399 (1956) or Chem. Ber. 22, 2091 (1889) known methods were cumbersome because they had to be carried out in two steps, according to the invention, the reaction is carried out in one step.

Starting materials for the process are N-methylpiperidine, N-methylmorpholine and methyl chloride. They are used in approximately equivalent amounts, optionally with a slight excess of methyl chloride.

The reaction can be carried out as follows: water and N-methylpiperidine 15 or N-methylmorpholine are introduced into the reaction vessel, the mixture is heated to the desired reaction temperature and then treated with methyl chloride. Advantageously, the reaction components are mixed with each other, e.g. by stirring. After completion of the reaction, the reaction solution is cooled to room temperature 20 and then diluted with water to the desired concentration of active substance.

The concentration of N-methylpiperidine or N-methylmorpholine in water at the beginning of the reaction can be varied within wide limits. Such concentrations are preferred which, upon completion of the reaction, give rise to such concentrations of the final products which are slightly above the concentration of the aqueous solutions intended for sale. But you can also start with dilute aqueous solutions and after completion of the reaction distill off some of the water used, without compromising the quality of the final product. The concentration of N-methylpiperidine or N-methylmorpholine in water should be so high that they have not completely dissolved from the beginning of the reaction or during the reaction.

K DK 159682 Β

Since methyl chloride is a gas, it is convenient to work in a closed apparatus. In the method according to the invention one can operate without pressure or under pressure. With pressure, the reaction proceeds somewhat faster. If working with overpressure, it is advisable that prior to introducing the methylene chloride into the reaction vessel, it is rendered almost air-free by partial evacuation, and that the desired pressure is then adjusted by introducing methyl chloride into the vessel.

10

If the reaction is operated at constant pressure during the reaction, the progressive reaction can be monitored on the amount of methylene chloride supplied.

The reaction is carried out discontinuously or continuously at a temperature between 0 and 100 ° C, preferably at least 20 ° C, preferably at 30 to 80 ° C, especially between 40 and 60 ° C.

20 The duration of the turnover is irrelevant to the quality of the turnover. Therefore, the reaction time can be set according to what is most economical. It can thus e.g. be more favorable to work without pressure because there is only one container for pressureless operation available, so that a longer reaction time must be included in the purchase.

At the end of the reaction, no more methylene chloride is taken up and the reaction solution has a pH of 6-7.

In that case, it is a clear, practically colorless liquid.

30

The reaction according to the invention runs almost completely to the desired end products, i.e. no by-products are produced, whereby the yield is practically quantitative.

The only by-products that may occur are from the contaminants of the starting materials. For example, when N- 35 6

DK 159682 B

methylpiperidi.net also contains small amounts of unsubstituted piperidine, which is produced by reaction with methylene chloride N-methylpiperidine hydrochloride, which due to the hydrochloride formation is not further methylated. Adding to the starting solution basic substances that release amines from corresponding amino hydrochlorides, e.g. sodium hydroxide, the above mentioned appearance of the hydrochloride of the tertiary amine can be prevented. When the appearance of the metal chloride produced by the amino hydrochloride and the basic additive does not interfere, the process can be made even more economical when starting from impure starting materials. Also, when a larger amount of metal chloride does not interfere, you can start from the secondary amines, ie. from 15 piperidine or morpholine and reacting them under the reaction conditions described above in the presence of an equivalent of a basic additive with methyl chloride. As the final product, an aqueous solution of a mixture of a mole of quaternary ammonium chloride and an equivalent of 20 metal chloride is obtained.

The process according to the invention also has the technical advantage of being very environmentally friendly. No solid or liquid wastes are produced at all, because the reaction solution is directly the desired final product. Gaseous discharges are largely preventable when emptying the reaction vessel and introducing it into the starting materials without prior venting of the vessel, which can be accomplished seamlessly by means of pumps.

As the aqueous solution after completion of the reaction contains some methyl chloride, this solution can in some circumstances be considered as the source of emission of 35 pollutants. In this case, after completion of the reaction, the solution can be passed over an evaporator or a distillation column, thus liberating the reaction solution 7

DK 159682 B

for methyl chloride. The aqueous distillate thus obtained can then be added again to the following production batch as diluent.

Both N, N-dimethylpiperidinium chloride and N, N-dimethylmorpholihium chloride can be produced in the same apparatus, which is economically important in certain circumstances. As needed, both products can also be prepared in common blend, which can be very reasonable, since both products in blend in some plant cultures can be used with particularly good results.

If one wishes to isolate the two products as solid crystalline substances, this is easily succeeded by evaporation of the corresponding aqueous solutions. These appear in the form of colorless coarse crystals of high purity and having a melting point above 300 ° C.

Embodiment

20 In a stirrer fitted with a heating jacket and with a volume of 100 parts by volume, 30 parts by volume of water and 15.6 parts by weight of N-methylpiperidine were introduced (parts by volume are parts by weight as liters per kilogram).

The apparatus was evacuated and heated to 50 ° C. At this temperature, a maximum of 1000 parts by volume of methyl chloride was supplied via a flow meter. and the mixture was kept under stirring.

30 After approx. For 2 hours a pressure of 2 bar was obtained, and this was maintained at the same level by the controlled addition of methyl chloride.

During the reaction, water was added to the heat jacket, the temperature of which was 55 eC, whereby the internal temperature could be kept at 49-50 ° C.

8

DK 159682 B

After 7.25 hours, the pressure remained constant without the addition of methyl chloride. An additional 0.75 hours was stirred and the apparatus was then emptied to such an extent that the bottom valve was still just covered, so that the voltage was not taken off by the container.

The solution thus obtained was a yellowish clear liquid which exhibited a pH of 6.9 and contained after a content determination at which N, N-dimethylpiperidinium chloride precipitated as tetraphenylborate complex and determined gravimetrically, , 46 parts by weight 1 volume fraction. The yield was thus quantitative.

The consumption of methyl chloride corresponded to a molar ratio of N-15 methylpiperidine to methyl chloride of 1: 1.02.

In a completely analogous manner, N-methylmorpholine and methyl chloride N, N-dimethylmorpholinium chloride were obtained, giving the reaction time 14 hours.

20 25 30 35

Claims (1)

Process for the preparation of Ν, Ν-dimethylpiperidinium chloride or N, N-dimethylmorpholinium chloride by reaction of N-methylpiperidine or N-methylmorpholine with methylating agents, characterized by reacting N-methylpiperidine or N-methylmorpholine. thyl chloride in the presence of water as diluent 10 at a temperature of 0 to 100 ° C and a pressure of between 1 and 7 bar. 15 20 25 30 35