GB1573239A - Preparation of dimethyl bis ammonium halides - Google Patents

Description

(54) PREPARATION OF DIMETHYL-BIS (ALKENYL)-AMMONIUM HALIDES (71) We, AKADEMIE DER WISSEN SCHAFTEN DER DDR, of 5 Rudower Chaussee, 1199 Berlin, German Democratic Republic, a Corporation organised under the laws of the German Democratic Republic, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention is concerned with a process for the preparation of dimethyl bis - (alkenyl) - ammonium halides and especially of dimethyl diallyl ammonium chloride (hereinafter referred to as DMDAAC).

The dimethyl - bis - (alkenyl) ammonium halides with which the present invention is concerned are compounds of the general formula:

wherein R, and R2, which can be the same or different, are hydrogen atoms or alkyl radicals containing up to 6 carbon atoms and Xs is a halide ion.

Representatives of this class of compounds are of interest as starting monomers for the preparation of linear or branched or partly cross-linked, watersoluble polyammonium compounds which, in the form of homo- or co-polymers, are used, for example, as flocculation agents, antistatic agents, electrically-conductive paper coatings and the like.

Compounds of general formula (I) in which R, is a hydrogen atom or a methyl radical, R2 is a hydrogen atom and Xe is a chloride ion are known and, according to U.S. Patent Specification No. 2,923,701, are prepared from an aqueous solution of dimethylamine, allyl or methallyl chloride and aqueous sodium hydroxide solution in a mole ratio of 1:3:1. According to Example 1 of this U.S. Patent Specification, DMDAAC can be prepared as follows: to a 40 /n aqueous solution of dimethylamine, there is first added the appropriate molar amount of allyl chloride and subsequently the molar amount of a 50% aqueous solution of sodium hydroxide, with reflux boiling.

After standing for 16 hours, a further 2 mole of allyl chloride per mole of dimethylamine are gradually added thereto and the reaction mixture boiled for 6.5 hours.

Excess allyl chloride is then separated off from the ammonium salt solution and the dilute sodium chloride-containing solution obtained is treated with active charcoal and the resultant DMDAAC solution used for polymerisation.

In U.S. Patent Specification No.

3,461,163, it is stated that the preparation of solutions of DMDAAC according to the process of U.S. Patent Specification No.

2,923,701 gives solutions thereof which still contain undesirable impurities which, in turn, are regarded as a reason for the formation of polymers with undesirably low molecular weights. According to U.S.

Patent Specification No. 3,461,163, solutions of DMDAAC of higher purity are obtained when molar amounts of allyl chloride and aqueous sodium hydroxide solution are added alternately and portionwise to the dimethylamine solution at temperatures of from 0 to 5"C., while controlling the pH value within the range of from 13 to 13.5; subsequently, a further 1.25 mole allyl chloride is added per mole dimethylamine at a temperature below 10"C., whereafter the reaction mixture is boiled until the pH value thereof has dropped below 7. The solution is then concentrated under reduced pressure for 12 hours. By means of this vacuum treatment, a purification is simultaneously carried out since, in this way, excess allyl chloride, as well as unreacted basic components, are removed. If necessary, there can follow a treatment with active charcoal for further purification.

Finally, U.S. Patent Specification No.

3,472,740 discloses that solutions of DMDAAC prepared according to the method of U.S. Patent Specification No.

2,923,701 can be purified by a number of purification operations, such as evaporation under reduced pressure, pH regulatedsteam distillation and treatment with active charcoal.

It is an object of the present invention to provide an economic process for the preparation of pure dimethyl - bis (alkenyl) - ammonium halides and especially of dimethyl - diallyl - ammonium chloride, with a reduced expenditure of starting materials in shorter periods of time and without direct purification operations.

Disadvantages of the above-mentioned methods for the preparation of pure DMDAAC solutions which, when polymerised lead to polymers of high molecular weight, are the long reaction times, the complicated method of carrying out the process according to U.S. Patent Specification No. 3,461,163 or the, in part, considerable expense of the purification operations, especially when using the process according to U.S. Patent Specification No. 3,472,740, as well as sometimes the use of a considerable excess of allyl chloride These deficiencies are reduced or removed by the process according to the present invention.

Therefore, the problem with which the present invention is concerned is to provide a process for the preparation of dimethyl bis - (alkenyl) - ammonium halides and especially of dimethyl - diallyl - ammonium chloride, which in the shortest possible reaction time and with the use of equimolar amounts or of a very small excess of alkenyl halide, leads, in one process step, without additional purification operations, to pure dimethyl - bis - (alkenyl) - ammonium halide solutions.

Thus, according to the present invention, there is provided a process for the preparation of dimethyl - diallyl ammonium halides of general formula (I) from 1 mole of dimethylamine in aqueous solution, at least 2 moles of an alkenyl halide of the general formula CHR2=CHR1-CH2X, in which R1, R2 and X have the same meanings as above, and 1 mole of sodium hydroxide in aqueous solution, wherein to the aqueous dimethylamine solution there is slowly and uniformly added one eighth of the stoichiometrically necessary amount of alkenyl halide at a temperature of from 10 to 250C. and preferably of from 10 to 200C., then very rapidly a further amount of alkenyl halide up to a total amount of 2.0 to 2.2 mole and preferably of 2.0 to 2.1 mole, per mole of dimethylamine, subsequently the aqueous sodium hydroxide solution is added uniformly at a temperature of from 10 to 250C. and preferably of 10 to 200C., whereafter, if desired, an inert gas, such as nitrogen, is passed through the reaction solution for a short period of time and the reaction solution is heated for about 2 hours to a temperature of from 45 to 1150C., preferably of 85 to 1050C. and more preferably of about 100"C., under a pressure of preferably up to 4.0 bar, whereafter the pressure is removed and, insofar as more than 2 mole allyl chloride have been used, the reaction mixture is flushed with an inert gas, such as nitrogen.

The sodium hydroxide is preferably used in the form of a 30 to 70% aqueous solution and more preferably of an approximately 50% aqueous solution.

By means of the process according to the present invention, solutions of dimethyl bis - (alkenyl) - ammonium halides of general formula (I) and preferably of dimethyl - diallyl - ammonium chloride are prepared, in comparison with the previously known process, in short periods of time and with a smaller consumption of alkenyl halides. The monomer solutions obtained do not contain any gas chromatographically-detectable substances which inhibit polymerisation, such as allyl alcohol, and can, therefore, be polymerised to give high molecular weight polymers either directly or after subsequent treatment operations, such as dilution. This is, in particular, achieved by the selected variants of the dosing in of the alkenyl halide and of the aqueous sodium hydroxide solution, as well as by carrying out the reaction under pressure under conditions which avoid those under which undesired byproducts are formed, such as too high pH values.

The following Example is given for the purpose of illustrating the present invention: Example 11.27 kg. (100 mole) 40 v dimethylamine solution were placed in a stainless steel kettle equipped with a stirrer, a thermometer, a cooler, inlet pipes and heating means. 1.91 kg. (25 mole) allyl chloride were then slowly and uniformly dosed into the dimethylamine solution at a temperature of about 15"C. Thereafter, 14.16 kg. (185 mole) allyl chloride were quickly added thereto, no change of temperature thereby taking place.

Subsequently, 8.0 kg. (100 mole) 50% aqueous sodium hydroxide solution were slowly and uniformly added at a reaction temperature of 150C. After the aqueous sodium hydroxide had been added, nitrogen was passed through the reaction solution for about 5 minutes and this then heated in the course of about 20 minutes to about the commencement of boiling, whereupon the apparatus was immediately closed off from the external atmosphere. The reaction mixture was then heated for about 2 hours under a pressure of about 2 bar to about 100"C. Subsequently, the pressure is carefully removed from the apparatus, excess allyl chloride thereby distilling off immediately and then, if desired, nitrogen briefly passed through the solution.

Dimethyl- diallyl - ammonium chloride was obtained in quantitative yield in the form of an aqueous solution which still contained dissolved therein 3.6% by weight of sodium chloride and also contained further sodium chloride suspended therein.

No polymerisation inhibiting substances, such as allyl alcohol, could be detected therein by gas chromatography.

WHAT WE CLAIM IS: 1. Process for the preparation of dimethyl - bis - (alkenyl) - ammonium halides of the general formula:

in which R, and R2, which can be the same or different, are hydrogen atoms or alkyl radicals containing up to 6 carbon atoms and Xs is a halide ion, from 1 mole dimethylamine in aqueous solution, at least 2 moles of an alkenyl halide of the general formula CHRfflCR1-CH2X, in which R1, R2 and X have the same meanings as above, and 1 mole of sodium hydroxide in aqueous solution, wherein to the aqueous dimethylamine solution there is slowly and uniformly added, at a temperature of from 10 to 250C., one eighth of the stoichiometrically necessary amount of alkenyl halide, thereafter very quickly a further amount of alkenyl halide up to a total amount of 2.0 to 2.2 mole per mole dimethylamine, subsequently the sodium hydroxide is added uniformly in the form of an aqueous solution at a temperature of from 10 to 250 C. and then the reaction solution is maintained for about 2 hours under pressure at a temperature of from 45 to 1 150C., whereafter the pressure is removed and, when more than 2 moles of alkenyl halide have been used, the reaction mixture is flushed with an inert gas.

2. Process according to claim 1, wherein the initially used amount of alkenyl halide is added at a temperature of from 10 to 200 C.

3. Process according to claim 1 or 2, wherein the alkenyl halide is added in a total amount of from 2.0 to 2.1 mole.

4. Process according to any of the preceding claims, wherein the sodium hydroxide solution is added at a temperature of from 10 to 200 C.

5. Process according to any of the preceding claims, wherein the reaction solution is maintained under pressure at a temperature of about 100"C.

6. Process according to any of the preceding claims, wherein the reaction solution, after the addition of the sodium hydroxide, is flushed with an inert gas.

7. Process according to any of the preceding claims, wherein the inert gas used is nitrogen.

8. Process according to claim 1 for the preparation of dimethyl - bis - (alkenyl) ammonium halides, substantially as hereinbefore described and exemplified.

9. Dimethyl - bis - (alkenyl) ammonium halides, whenever prepared by the process according to any of claims 1 to 8.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. temperature of about 15"C. Thereafter, 14.16 kg. (185 mole) allyl chloride were quickly added thereto, no change of temperature thereby taking place. Subsequently, 8.0 kg. (100 mole) 50% aqueous sodium hydroxide solution were slowly and uniformly added at a reaction temperature of 150C. After the aqueous sodium hydroxide had been added, nitrogen was passed through the reaction solution for about 5 minutes and this then heated in the course of about 20 minutes to about the commencement of boiling, whereupon the apparatus was immediately closed off from the external atmosphere. The reaction mixture was then heated for about 2 hours under a pressure of about 2 bar to about 100"C. Subsequently, the pressure is carefully removed from the apparatus, excess allyl chloride thereby distilling off immediately and then, if desired, nitrogen briefly passed through the solution. Dimethyl- diallyl - ammonium chloride was obtained in quantitative yield in the form of an aqueous solution which still contained dissolved therein 3.6% by weight of sodium chloride and also contained further sodium chloride suspended therein. No polymerisation inhibiting substances, such as allyl alcohol, could be detected therein by gas chromatography. WHAT WE CLAIM IS:

1. Process for the preparation of dimethyl - bis - (alkenyl) - ammonium halides of the general formula:

in which R, and R2, which can be the same or different, are hydrogen atoms or alkyl radicals containing up to 6 carbon atoms and Xs is a halide ion, from 1 mole dimethylamine in aqueous solution, at least 2 moles of an alkenyl halide of the general formula CHRfflCR1-CH2X, in which R1, R2 and X have the same meanings as above, and 1 mole of sodium hydroxide in aqueous solution, wherein to the aqueous dimethylamine solution there is slowly and uniformly added, at a temperature of from 10 to 250C., one eighth of the stoichiometrically necessary amount of alkenyl halide, thereafter very quickly a further amount of alkenyl halide up to a total amount of 2.0 to 2.2 mole per mole dimethylamine, subsequently the sodium hydroxide is added uniformly in the form of an aqueous solution at a temperature of from 10 to 250 C. and then the reaction solution is maintained for about 2 hours under pressure at a temperature of from 45 to 1 150C., whereafter the pressure is removed and, when more than 2 moles of alkenyl halide have been used, the reaction mixture is flushed with an inert gas.

2. Process according to claim 1, wherein the initially used amount of alkenyl halide is added at a temperature of from 10 to 200 C.

3. Process according to claim 1 or 2, wherein the alkenyl halide is added in a total amount of from 2.0 to 2.1 mole.

4. Process according to any of the preceding claims, wherein the sodium hydroxide solution is added at a temperature of from 10 to 200 C.

5. Process according to any of the preceding claims, wherein the reaction solution is maintained under pressure at a temperature of about 100"C.

6. Process according to any of the preceding claims, wherein the reaction solution, after the addition of the sodium hydroxide, is flushed with an inert gas.

7. Process according to any of the preceding claims, wherein the inert gas used is nitrogen.

8. Process according to claim 1 for the preparation of dimethyl - bis - (alkenyl) ammonium halides, substantially as hereinbefore described and exemplified.

9. Dimethyl - bis - (alkenyl) ammonium halides, whenever prepared by the process according to any of claims 1 to 8.