CS261038B1 - A method for preparing an anion exchanger comprising strongly basic pyridinium functional groups - Google Patents

Abstract

The method of preparing an anion exchanger consists in the reaction of a suspension bead copolymer of 2-vinylpyridine and/or 4-vinylpyridine, or other vinyl monomers and divinylbenzene with epichlorohydrin in an aqueous medium at a temperature of 20 to 90 °C in a molar ratio of copolymer nitrogen to epichlorohydrin of 1:0.6 to 1:1.2 for a period of 1 to 24 hours to form strongly basic 2,3-dihydroxypropylpyridinium chloride functional groups. The epichlorohydrin used is suitable for synthesis both technically in terms of reactivity and availability and also from a health point of view with careful handling.

Description

The present invention relates to a process for preparing an anion exchanger containing strongly basic pyridinium functional groups.

Strongly basic polymeric anion exchangers containing quaternary nitrogen functional groups of the benzyltrimethylammoniumbenzyldimethyl (2-hydroxyethyl) ammonium or benzylpyridinium type are synthesized on styrene-divinylbenzene copolymers or other crosslinking agents with two or more vinyl groups. Their synthesis consists essentially in the reaction of a styrene-divinylbenzene copolymer with chloromethyl ether in the presence of Friedel-Crafst catalysts and the subsequent reaction of copolymers containing chloromethylene groups, i.e. polyvinylbenzyl chloride, with a tertiary amine such as trimethylamine, dimethylaminoethanol, pyridine and the like. polyvinylbenzyl chloride with a tertiary nitrogen of an amine or pyridine heterocycle, most of these groups are readily converted to quaternary ammonium or pyridinium functional groups.

However, this relatively easy and successful reaction with high conversion yields also has a significant technological or health risk, namely the use and handling of chloromethyl ether and the reaction liquid after chloromethylation. Chloromethyl ether, and in particular the reaction liquid after chloromethylation, contains certain, and sometimes fairly high, amounts of bischloromethyl ether, a substance with proven potent carcinogenic activity. Monochloromethyl ether itself has mutagenic effects and is also suspected of being carcinogenic.

In the synthesis of strongly basic anion exchangers, an attempt has therefore been made to replace this preparation path with another, without the use of chloromethyl ether, e.g. vinylpyridine and / or derivatives and homologues thereof, followed by quaternization (alkylation) of pyridine nitrogen.

Among the pyridine vinyl compounds used to synthesize these types of anion exchangers, a number of such literature is disclosed, such as 2-, 3-, or 4-vinylpyridine, 2-methyl-4-vinylpyridine, 2-methyl-5-vinylpyridine, 2-methyl-6- vinylpyridine, 3-methyl-4-vinylpyridine, 5-methyl-2-vinylpyridine, 4-methyl-2-vinylpyridine, 2,4-divinylpyridine, 5-ethyl-2-vinylpyridine, 1,3-bis (dimethylamino) -2 - (5-vinyl-2-pyridine) propane, etc.

Divinylbenzene, but also divinylpyridine, ethylene glycol diacrylate, or also dimethacrylate, butadiene, divinylacetylene, were most commonly used as the crosslinking agent for the copolymer. In many cases, some comonomers have been used in copolymerization, especially styrene, vinyltoluene, but also acrylonitrile, isoprene, chloroprene, acrylic or methacrylic acid esters and the like.

A variety of reagents such as methyl chloride, methyl bromide, benzyl chloride, methyl iodide, butyl bromide, dimethyl sulfate, methyl p-toluenesulfonate, dodecyl bromide, mono- and dichlorohydrin glycerine, dimethylamine hydrochloride, dimethylamine, dimethylamine, and dimethylamine were used as alkylating agents to convert tertiary pyridine nitrogen to quaternary nitrogen. in formaldehyde solution. All of these alkylating agents have the disadvantage that they are either too expensive, such as methyl iodide, methyl bromide, or difficult to work by their odor and mucosal action, such as benzyl chloride, or their vapors are too hazardous to health, e.g. dimethyl sulfate, or conversion Tertiary nitrogen to quaternary nitrogen is too low - mono - and dichlorohydrin glycerin, allyl chloride.

The above mentioned drawbacks are eliminated by the present invention, whose subject is a process for preparing the anion exchangers comprising a strongly basic functional groups pyridinium based on copolymers of vinylpyridine, or other ethylenically-unsaturated monomers and divinylbenzene, characterized in that the suspension bead copolymer of 2 ^J vinylpyridine and / or 4-vinylpyridine, optionally other vinylic monomers from the group comprising styrene, acrylic and / or methacrylic esters and vinyl acetate, with divinylbenzene are reacted with epichlorohydrin in an aqueous medium at a temperature of 20 to 90 ° C in a molar nitrogen ratio of copolymers to epichlorohydrin of 1: 0.6 to 1 : 1.2 for 1 to 24 hours.

In particular, the advantage of the present invention is that epichlorohydrin can be used for quaternization of pyridine nitrogen to pyridinium nitrogen, which is technically satisfactory both in terms of reactivity and availability, but also in terms of health with careful handling as in epoxy resin technology. In an aqueous environment, the reaction of epichlorohydrin with polyvinylpyridine nitrogen takes place via the following reaction mechanisms:

0H ^(-, + CH _o - CH-CH _O C1 - from CH.-CH-CH 2 CH 1 - »CH-CH-CH- + C1 *

-2 / 2 ϊ 2 i. . 2 2 _x r 2 —o / OH ΙοI ^l-> OH Ό

CN | +) -H 2 N 1 + J -CH 3 -CH-CH,

(1) -> 1, ² and ² - OH OH

The product of this reaction is tangentially stable in the form of its small-scale form, such as (2,3-dihydroxypropylvinylpyridinium) chloride, which can be depleted. However, the reaction may be accompanied by other side reactions by direct reaction of the chlorine of epichlorohydrin with nitrogen

-CH, -CH-CH,

V + CI (-) or by reacting the epoxy group directly with hydrated polyvinylpyridine nitrogen

4-CH. —CH — CM— ————————————————————————N N N —CH. —CH — CH.CI

W 'in' Vo »h

The possibilities of reacting epichlorohydrin with hydroxyl of the functional group could be further considered, but these reactions, if any, are very limited, since the agreement between the quaternary nitrogen values in the resin and the weight gain of the resin after quaternization is indicative of only one epichlorohydrin molecule with one nitrogen of the polymer.

The following Examples illustrate the preparation of the anion exchange resin by reacting the copolymers of 2- and / or 4-vinylpyridine with epichlorohydrin, which illustrate the preparation of the anion exchangers of the present invention.

Example 1

The bead suspension copolymer was prepared from a mixture of 255 wt. parts of 2-vinylpyridine,

36.4 wt. % by weight of divinylbenzene (consisting of: 64 wt.% divinylbenzene, 32 wt.% ethylvinylbenzene, 3 wt.% diethylbenzene and 1 wt.% naphthalene), 1.5 wt. % benzoylperoxide and 2.9 wt. part of azobisisobutyronitrile in 1% starch sebum at 68 ° C and after the polymerization reaction was cured by further heating for 2 hours at 80 ° C, washed thoroughly with water, with a particle size of 0.3 to 1.0 mm in diameter (yield 94%) to monomers). The copolymer was mixed in 800 wt. parts of distilled water and a suspension heated to 80 ° C. Subsequently, epichlorohydrin, 165 wt. parts. The copolymer swelled strongly during the epichlorohydrin drip and changed from light yellow to dark crimson. After completion of the dropwise addition, the mixture was stirred for 1 h and then cooled, acidified with 7% chloro-261038 hydrogen to a distinctly acidic reaction and stirred for an additional 30 minutes. During and after acidification, the volume of the anion exchanger increased only slightly, the anion exchanger was thoroughly washed with water and its properties determined. 770 wt. % of wet suction anion exchanger having a particle size of 0.4 to 1.25 m in diameter, having a moisture content of 52 to 56 wt. with a exchange capacity of slightly basic 1.35 meq / ml and strongly basic 1.10 meq / ml.

Example 2

A copolymer prepared from the same process as in Example 1, from 127 wt. parts by weight of 4-vinylpyridine (97%), 10 wt. parts of styrene, 4 wt. parts of vinyl acetate, 20 wt. parts by weight of divinylbenzene (composition as in Example 1), 1.5 wt. % benzoyl peroxide and 1.0 wt. % of azobisisobutyronitrile was quaternized in an aqueous suspension of 72.5 wt. Then, the anion exchange resin was washed thoroughly with water, acidified with 7% hydrochloric acid until a clearly acidic reaction, and after stirring for 1 hour again thoroughly washed with water. The anion exchanger was dark red-brown in color, had a moisture content of 58 wt%, a weak base capacity of 1.2 meq / ml and a strong base exchange capacity of 1.35 meq / ml.

Example 3

The copolymer prepared by the suspension copolymerization according to Example 1, from 115 wt. parts of 2-vinylpyridine and 115 wt. parts by weight of 4-vinylpyridine, 15 wt. parts of styrene and 5 wt. parts of methyl methacrylate and 28 wt. parts of divinylbenzene were quaternized in an aqueous suspension in 700 wt. parts of water with stirring at 70 ° C by dropwise addition of 162 wt. After the addition, the anion exchanger slurry was stirred at 80 ° C for 1 hour, then acidified after cooling to 40 ° C until the reaction was clearly acidic with 7% hydrochloric acid and stirred for a further 30 minutes. After cooling, wash thoroughly with water until the acidic reaction of the eluate is lost.

The anion exchanger obtained is a deep orange in color and contains from 55 to 57% by weight. It had a low basic exchange capacity of 1.12 meq / ml and a strong basic exchange capacity of 1.25 meq / ml.

Claims (1)

SUBJECT OF THE INVENTION Process for preparing an anion exchanger containing strongly basic pyridinium functional groups based on copolymers of vinylpyridine and divinylbenzene, characterized in that the suspension bead copolymer of 2-vinylpyridine and / or 4-vinylpyridine or other vinyl monomers from the group comprising styrene, acrylic esters and / or methacrylic vinyl acetate with divinylbenzene is reacted with epichlorohydrin in an aqueous medium at 20 to 90 ° C in a molar ratio of nitrogen copolymers to epichlorohydrin of 1: 0.6 to 1: 1.2 for 1 to 24 hours. Severografia ,. n. p., MOST