SU671730A3 - Method of producing n,n-dimethyl piperidinium chloride or dimethyl morpholinium chloride - Google Patents

Description

one

This invention relates to an improved process for the preparation of M, N-dimethylpiperidinium chloride or H, N-dimethylmorpholinium chloride, which are used as herbicides.

A known method for producing N, N-dimethylpiperidinium chloride by reacting N methylpiperidine with methyl iodide in a mixture of benzene and methanol at 150–200 ° C in an autoclave, followed by transferring the obtained iodide N, N-dimethylpiperidine to its chloride by ion-exchange chromatography 1.

The disadvantages of this method are its two-stage process, carrying out the process in an autoclave and the use of flammable organic solvents.

Also known is the closest to the proposed method for the preparation of N, N-dimethyl-morpholini or S, N-dimethyl-piperidinium chlorides by reacting the corresponding secondary amines with methyl chloride in an organic solvent, such as alkanols, at a temperature O-100 ° C and a pressure from normal to 10 atm, in the presence of acid acceptor from the number of hydroxides, carbonates of alkali metals 2.

The disadvantage of the method is its complexity associated with the use of a flammable organic solvent and an acid acceptor, the process of separating the target products from a mixture with sodium chloride and an organic solvent.

The purpose of the invention is to simplify the process.

This goal is achieved by the method of obtaining N, N-dimethylpiperidinium chloride or M, M-dimethylmorpholinium chloride by reacting N-methylpiperidine or N-methnmorpholine with methyl chloride in water at a temperature O-100 ° C.

A distinctive feature of the method according to the invention is the use of water as a solvent.

With the high purity of the target product and high yield, the method according to the invention eliminates flammable organic solvents, acid acceptors, isolation of the target compounds, and eliminates environmental pollution, since the resulting product can be used as an herbicide without additional treatment.

The starting materials N-methylmorpholine, N-methylpiperidine and methyl chloride are used in equimolar amounts, possibly with a slight excess of methyl chloride.

The proposed method can be carried out, for example, as follows.

Water and monomethylamine are charged to the reactor, the mixture is heated to the desired reaction temperature, followed by treatment with methyl chloride with stirring. At the end of the reaction, the reaction solution is cooled to room temperature, after which it is diluted with water to the desired concentration of the active patch.

The concentration of monomethylamines in the water of the starting mixture can be varied within a wide range. Concentrations can be used, giving at the end of the reaction the concentrations of the target products are slightly higher than the concentrations intended for the sale of aqueous solutions. It is possible, of course, to proceed from the dilute aqueous solution and at the end of the interaction part of the water used is distilled off. The concentration of monomethylamines in water can also be so high that they did not dissolve at the beginning or during the course of its interaction.

Because chloris. Methyl is a gas, it is recommended to work in a closed vessel. The proposed method can be operated without pressure or under increased pressure. When pressure is applied, the reaction proceeds slightly faster. When operating without overpressure, it is recommended that the methyl chloride is introduced into the reactor free of air and then the required pressure is established by introducing methyl chloride.

If the process is carried out at constant pressure, the progress of the reaction can be monitored by the amount of methyl chloride introduced.

The reaction is usually carried out at 30-80 ° C, in particular 40-60 ° C, in a batch or continuous manner.

The duration of the interaction does not affect the quality of the target products.

By the end of the reaction, when the methyl chloride is no longer absorbed, the pH of the reaction solution is 6-7 and the solution is a clear, almost colorless liquid.

The only possible by-products are impurities from the starting materials. If, for example, N-methylpiperidine contains small amounts of unsubstituted piperidine,. then by reaction with methyl chloride N-methylpiperidine hydrochloride is formed, which is no longer methylated due to the formation of hydrochloride. If basic substances are added to the initial solution and the corresponding amines are released from the amino-hydrochlorides, for example sodium hydroxide, the formation of tertiary amine hydrochloride can be prevented. If the metal chloride formed from aminohydrochloride does not interfere, then the method can be even more economical if appropriate, allowing the use of contaminated starting amines. Since a larger amount of methyl chloride does not interfere, it is possible from the very beginning to proceed from secondary amines, i.e., piperidine or morpholine, respectively, by reacting them under the indicated conditions with methyl chloride in the presence of a base equivalent. In this case, an aqueous solution of a mixture of 1 mol of a quaternary chloride salt and an equivalent of metal chloride is obtained as the desired product.

Since the aqueous solution still contains some methyl chloride at the end of the reaction, this solution can be considered an appropriate source of contamination if appropriate. In this case, the solution

The reaction can be passed through an evaporator or distillation column, thereby removing methyl chloride from the reaction solution. The aqueous distillate thus obtained can be reacted as a diluent.

If the isolation of compounds in solid crystalline form is required, this is easily achieved by stripping the corresponding

water solutions. Colorless coarse crystals of high purity are obtained with mp. above 300 ° C.

Example. To a reactor equipped with a stirrer and jacket for heating, with a capacity

100 liters of load 30 liters of water and 15.6 wt. including N-methylpiperidne.

The reactor is degassed and heated to 50 ° C. At this temperature, 1000 liters of chloride are introduced through the flow meter.

methyl per hour and the mixture is stirred.

After 2 hours, a pressure of 2 atm is reached and it is maintained by the constant addition of methyl chloride and the whole process is carried out at 49-50 ° C.

After 7.25 hours the pressure stops falling and remains constant. Stir for another 3/4 h, then unload the reactor so that the valve at the bottom remains covered with liquid and is not discharged.

pressure in the reactor.

The solution thus obtained is a yellowish transparent liquid with a pH of 6.9; according to the results of analysis by precipitation, it contains: L, L1-dimethylpiperidinium chloride in the form of a tetraphenylborate complex and subsequent gravimetry of 0.46 kg / l of the target product (quantitative yield). Consumption of methyl chloride corresponds

the molar ratio of N-methylpiperidine and methyl chloride is 1: 1.02.

Similarly, N, K-dimethylmorpholinium chloride is obtained from N-methylmorpholine and methyl chloride (reaction time

14h)

Claims (2)

1.Schmid K. et al. Der sterische Verlauf der thermischen zersetung von unsymmetrischen quartaren Dimethylammonium zalzen, "Helv. Chim. Acfa, 1956, 39, s. 399 2. For the FRG 224750, cl. 12p3 / 00, publ. 1973.