Copolymer, a process for its preparation and its use as a sorbent

The crosslinked copolymer containing 75 to 99.9% by weight of recurring units of a pyridyl, quinolyl, isoquinolyl or pyrazinyl compound containing a polymerizable olefinic group, 0.1 to 25% by weight of units of a crosslinking agent and 0 to 25% by a weight of units of a polymerizable organosilicon and/or organoboron compound and, based on 100% by weight of the sum of the abovementioned units, 5 to 350% by weight of units of an N-vinyl-amide, is prepared by bead polymerization and used as a sorbent for acid substances from their aqueous solutions.

The present invention relates to a crosslinked, porous bead-like copolymer, 
a process for its preparation and its use as a sorbent, in particular for 
removing acid substances from solvents. 
The removal of carboxylic acids and mineral acids from solvents is becoming 
increasingly more important in industry. This removal can be effected with 
exchanger resins. Thus, Japanese patent specification No. 24,561/1971 
describes a process for removing carboxylic acids using basic anion 
exchangers of the styrene type. The amount of sorbed carboxylic acid is 
only small in this process, and in addition the desorption must be carried 
out with acetone and carbon dioxide gas under a pressure of 0.5 to 20 bar, 
which requires considerable expenditure, especially on a large industrial 
scale. 
A process for isolating carboxylic acids from an aqueous solution is known 
from German Pat. No. C2-3,043,766, in which a crosslinked polymeric 
compound having a pyridine skeleton structure is used as the sorbent. 
Divinylbenzene, divinyl phthalate and ethylene glycol diacrylate are 
mentioned as crosslinking agents. An aliphatic alcohol, a ketone or a 
carboxylic acid ester is used for the desorption. However, the capacity of 
the sorbent used is still too low, and in addition the sorbent swells too 
greatly, so that the flow resistance or the flow time increases. 
It has now been found, surprisingly, that the copolymer according to the 
invention has a high sorption capacity for acid substances and a low 
swelling capacity. The crosslinked porous, beadlike copolymer according to 
the invention contains 75 to 99% by weight of recurring units of a 
pyridyl, quinolyl, isoquinolyl or pyrazinyl compound containing a 
polymerisable olefinic group or of several such compounds, 0.1 to 25% by 
weight of units of an n-valent crosslinking agent or of several n-valent 
crosslinking agents and 0 to 25% by weight of units of a polymerisable 
organosilicon and/or organoboron compound or of several such compounds 
and, based on 100% by weight of the sum of the abovementioned units, 5 to 
350% by weight of units of an N-vinyl-amide of the general formula I 
CH.sub.2 .dbd.CH--N(R.sup.1)--C(R.sup.2).dbd.0, wherein R.sup.1 denotes 
hydrogen, methyl or ethyl and R.sup.2 denotes hydrogen or (C.sub.1 
-C.sub.3)-alkyl, or of several such N-vinyl-amides, and 0 to 40% by weight 
of units of another polymerisable compound or of several such compounds, n 
being a number equal to or greater than 2 and it being possible for the 
pyridyl, quinolyl, isoquinolyl or pyrazinyl compound also additionally to 
have one other or several other substituents. 
Besides hydrogen, R.sup.2 can denote methyl, ethyl, propyl or isopropyl. 
Preferably, R.sup.1 and R.sup.2 independently of one another denote 
hydrogen or methyl. 
In many cases, the copolymer contains, based on 100% by weight of units of 
the polymerisable heterocyclic compounds, units of the crosslinking agents 
and any units present of polymerisable organoboron and/or organosilicon 
compounds, advantageously only 0 to 25% by weight of units of other 
polymerisable compounds, instead of 0 to 40% by weight of units of other 
polymerisable compounds. Based on the already mentioned 100% by weight of 
units of polymerisable heterocyclic compounds, of crosslinking agents and 
of any organoborn and/or organosilicon compounds present, the copolymer 
can contain, for example, 10 to 40% by weight, preferably 10 to 110% by 
weight and particularly preferably 10 to 250% by weight of units of one or 
more N-vinyl-amides of the general formula I. 
The copolymer according to the invention preferably contains 80 to 99% by 
weight of units of a pyridyl, quinolyl, isoquinolyl or pyrazinyl compound 
containing a polymerisable olefinic group or of several such compounds, 1 
to 20% by weight of units of an n-valent crosslinking agent or of several 
n-valent crosslinking agents, and 0 to 19% by weight of units of a 
polymerisable organosilicon and/or organoboron compound or of several such 
compounds, and, based on 100% by weight of the sum of the abovementioned 
units, 10 to 250% by weight of units of an N-vinyl-amide of the general 
formula I or of several such N-vinyl-amides, and 0 to 25% by weight of 
units of another polymerisable compound or several such compounds, n 
having the meaning already given and it being possible for the pyridyl, 
quinolyl, isoquinolyl or pyrazinyl compound also additionally to have one 
other or several other substituents. 
Those copolymers according to the invention which contain at least 0.1% by 
weight, preferably 0.1 to 10% by weight, of units of polymerisable 
organosilicon and/or organoboron compounds are also particularly 
preferred, especially if these compounds act as units of n-valent 
crosslinking agents. 
Those copolymers according to the invention which contain no units of other 
polymerisable compounds are also preferred. 
The copolymer according to the invention contains units of a pyridyl, 
quinolyl, isoquinolyl or pyrazinyl compound containing a polymerisable 
olefinic group or of several such compounds, and furthermore units of one 
or more crosslinking agents and units of one or more N-vinyl-amides. If 
appropriate, the copolymer according to the invention can furthermore 
contain units of one or more polymerisable organosilicon and/or 
organoboron compounds and units of one or more other polymerisable 
compounds. Units here are understood as meaning the groups, randomly 
distributed in the copolymer, which are formed from the polymerisable 
monomeric compounds used for the preparation of the copolymer. 
The polymerisable olefinic group of the pyridyl, quinolyl, isoquinolyl or 
pyrazinyl compound is as a rule bonded directly, but if appropriate also 
indirectly, for example via an oxygen or sulphur atom, to the nucleus and 
usually has the formula II 
EQU --(CH.sub.2).sub.m --C(R.sup.3).dbd.C(R.sup.4)H (II) 
wherein R.sup.3 and R.sup.4 independently of one another denote hydrogen or 
(C.sub.1 -C.sub.4)alkyl and m denotes a number from 0 to 4. The 
combination of H/CH.sub.3 or CH.sub.3/H, or H/H is preferred for the 
radicals R.sup.3 and R.sup.4. m is preferably 1 or, particularly 
preferably, 0. 
If the pyridyl, quinolyl, isoquinolyl or pyrazinyl compound containing a 
polymerisable olefinic group contains further substituents, it carries, in 
particular, one, two or three (C.sub.1 -C.sub.4)alkyl and/or OH 
substituents. The alkyl substituents can be straight-chain or branched, as 
can the alkyl radicals R.sup.3 and R.sup.4. The pyridyl, quinolyl, 
isoquinolyl or pyrazinyl compound containing a polymerisable olefinic 
group is substituted, in particular, by one or two alkyl radicals or by 
one OH group or by one OH group and one alkyl radical. 
The recurring units, contained in the copolyer according to the invention, 
of the pyridyl, quinolyl, isoquinilyl or pyrazinyl compound containing a 
polymerisable olefinic group thus usually have the formula III 
##STR1## 
wherein R denotes pyridyl, quinolyl, isoquinolyl or pyrazinyl, R.sup.3 and 
R.sup.4 denote hydrogen or (C.sub.1 -C.sub.4)alkyl and X denotes --O--, 
--S-- or --(CH.sub.2).sub.m --, where m denotes a number from 0 to 4, 
preferably 1 or, in particular, O, X thus denotes, in particular, a direct 
bond, and the radical R can also be mono- or poly-substituted, in 
particular by (C.sub.1 -C.sub.4)alkyl and/or OH groups. The preferred 
possible alkyl substituent for R is methyl or ethyl. The radicals R and/or 
R.sup.3 and/or R.sup.4 can be identical or different in the recurring 
units of the formula III in the copolymer. Polymerisable olefinic groups 
are, in particular, the vinyl, allyl, methallyl or isopropenyl group. 
Suitable examples of a pyridyl, quinolyl, isoquinolyl or pyrazinyl compound 
containing a polymerisable olefinic group are: 2-vinyl-pyridine, 
3-vinyl-pyridine, 4-vinyl-pyridine, 3-isopropenyl-pyridine, 
2-vinyl-5-methyl-pyridine, 2-methyl-5-vinyl-pyridine, 
3-methyl-5-vinyl-pyridine, 2,4-dimethyl-6-vinyl-pyridine, 
3-methyl-4-vinyl-pyridine, 3-ethyl-4-vinyl-pyridine, 
3-methyl-2-vinyl-pyridine, 3-ethyl-2-vinyl-pyridine, 
4-methyl-4-vinyl-quinoline, 2-methyl-5-vinyl-quinoline, 
1-methyl-5-vinyl-isoquinoline, 2-isopropenyl-quinoline, 2-vinyl-pyrazine, 
2-vinyl-5-ethyl-pyridine, 2-vinyl-4,6-dimethyl-pyridine, 2-vinyl-quinoline 
and 2-methyl-3-vinyl-8-hydroxy-quinoline. Of the pyridyl, quinolyl, 
isoquinolyl or pyrazinyl compounds, the pyridyl compounds, especially the 
vinyl-pyridine compounds and in particular 4-vinyl-pyridine, are 
preferred. 
Up to 50% by weight of the units, contained in the copolymer, of a pyridyl, 
quinolyl, isoquinolyl or pyrazinyl compound containing a polymerisable 
olefinic group can be replaced by units of a heterocyclic 5-membered ring 
compound which contains a polymerisable olefinic group and has at least 
one protonatable nitrogen atom in the ring, or of several such compounds. 
The same statements apply to the polymerisable olefinic group of the 
heterocyclic 5-membered ring compound mentioned as to the polymerisable 
olefinic group of the pyridyl, quinolyl, isoquinolyl or pyrazinyl 
compound. The heterocyclic 5-membered ring compound can contain, for 
example, one, two, three or four nitrogen atoms, at least one of which 
must be protonatable it also being possible for the heterocyclic ring 
optionally additionally to contain another hetero-atom or several other 
hetero-atoms, in particular oxygen and/or sulphur. Protonatable nitrogen 
atoms are basic nitrogen atoms with a free electron pair, which are 
incorporated in the 5-membered ring as, for example, --N.dbd., --NH-- or 
##STR2## 
Nitrogen atoms which, for example, are adjacent to a keto group no longer 
have basic properties and thus can no longer be protonated. The 
heterocyclic 5-membered ring can be saturated, partly saturated or 
unsaturated and can be, for example, an imidazole, imidazoline, oxazole, 
oxazoline, oxazolidine, thiazole, oxadiazole, pyrrole, triazole or 
tetrazole, and can optionally also contain one or more (C.sub.1 
-C.sub.4)alkyl and/or (C.sub.2 -C.sub.4)hydroxyalkyl groups. Polymerisable 
olefinic groups are, in particular, the vinyl, allyl, methallyl or 
isopropenyl group. Examples which may be mentioned of a heterocyclic 
5-membered ring compound which contains a polymerisable olefinic group and 
has at least one protonatable nitrogen atom in the ring are: 
1-vinyl-1,2,3-triazole, 1-vinyl-1,2,4-triazole, 4-vinyl-1,2,3-triazole, 
5-vinyl-1,2,3-triazole, 1-vinyl-1,2,3,4-tetrazole, 
2-vinyl-1,2,3,4-tetrazole, 2-allyl-1,2,3,4-tetrazole, 
1-allyl-1,2,3,4-tetrazole, 1-methyl-5-vinyl-1,2,3,4-tetrazole, 
2-methyl-5-vinyl-1,2,3,4-tetrazole, 3-vinyl-1,2,4-oxadiazole, 
3-vinyl-5-methyl-1,2,4-oxadiazole, 3-isopropenyl-1,2,4-oxadiazole, 
2-isopropenyl-1,3,4-oxadiazolin-5-one, 3-isopropenyl-1,2,4-oxadiazole, 
3-isopropenyl-5-methyl-1,2,4-oxadiazole, 2-vinyl-oxazoline, 
2-vinyl-oxazoline, 2-isopropenyl-oxazoline, 2-vinyl-3-methyl-oxazolidine, 
2-vinyl-thiazole, 4-vinyl-thiazole, 1-vinyl-2-imidazoline, 2-vinyl-4-(or 
5-)-methyl-2-imidazoline, 1-vinyl-2-methyl-2-imidazoline, 
1-vinyl-imidazole, 1-methyl-2-vinyl-imidazole, 1-vinyl-2-methyl-imidazole, 
1-vinyl-4-(2-hydroxyethyl)-imidazole, N-vinyl-pyrrole, 
2-isopropenyl-2-imidazoline, 2-vinyl-3-methyl-2-imidazoline and 
1-vinyl-2,4-dimethyl-imidazole. 
Of the heterocyclic 5-membered ring compounds which contain a polymerisable 
olefinic group and have at least one protonatable nitrogen atom in the 
ring, the vinyl-imidazoles, in particular 1-vinyl-imidazole, are 
preferred. 
The crosslinking agent links n polymer chains with one another, n being a 
number equal to or greater than 2. In particular, n is 2,3 or 4, 
preferably 2. 
Examples of suitable crosslinking agents are compounds which contain space 
polymerisable radicals, in particular of the formulae CH.sub.2 .dbd.CH--, 
CH.sub.2 .dbd.CH--CH.sub.2 --, CH.sub.2 .dbd.CH(R.sup.5)--CO--or CH.sub.2 
.dbd.CH(R.sup.5)--CO--O--, in the molecule, n having the meaning already 
given, and usually being 2, 3 or 4, preferably 2 or 3, and R.sup.5 
denoting hydrogen or (C.sub.1 -C.sub.4)alkyl, in particular hydrogen or 
methyl. Examples of such crosslinking agents are: triallyl cyanurate, 
triallyl phosphate, N,N', N"-tris-acryloyl-perhydrotriazine, 
1,2,3-trivinyloxypropane, tetraallyloxyethane, pentaallyl-sucrose, 
triallyl-amine, N,N',N"-tris-(2-acryloyloxyethyl- or 
-methacryloyloxyethyl) isocyanurate, diallyl ethenephosphonate, ethylene 
glycol 1,2-bis-(ethenephosphonate) and furthermore, generally , compounds 
of the formula IV, V or VI 
EQU (CH.sub.2 .dbd.CH).sub.n --R.sup.6 (IV) 
EQU (CH.sub.2 .dbd.CH--CH.sub.2).sub.n --R.sup.7 (V) 
EQU (CH.sub.2 .dbd.CH(R.sup.5)--CO).sub.n --R.sup.8 (VI) 
wherein R.sup.5 has the meaning already given, n usually denotes 2, 3 or 4, 
preferably 2 or 3, R.sup.7 represents the radical formed by removing n 
acid H atoms from a di-, tri-, tetra- or poly-carboxylic acid, R.sup.8 
represents the radical formed by removing n hydroxylhydrogen atoms from a 
di-, tri-, tetra- or poly-ol and R.sup.6 represents the radical formed by 
removing n hydrogen atoms from an aliphatic, aromatic or heteroaromatic 
hydrocarbon. 
Suitable crosslinking agents of the formula IV are divinylbenzenes, in 
particular 1,4-divinylbenzene, trivinylbenzenes, divinylpyridines and 
divinylquinolines. 
Examples of suitable crosslinking agents of the formula V are triallyl 
tricarballylate, triallyl aconitate, triallyl citrate, triallyl 
trimesinate, triallyl trimellitate, diallyl oxalate, divinyl phthalate and 
diallyl maleate, fumarate, adipate or phthalate. 
Examples of suitable crosslinking agents of the formula VI are 
trimethylolpropane tri-acrylate and -methacrylate, pentaerythritol 
tetra-acrylate and -methacrylate, pentaerythritol triacrylate and 
-methacrylate, dimethylene glycol diacrylate or dimethacrylate and 
butylene glycol diacrylate or dimethacrylate. 
Examples of compounds of the general formula VI are the diacrylates and 
dimethacrylates of ethylene glycol, diethylene glycol and polyethylene 
glycols 200 to 600 and the dimethacrylates of polyethylene glycols 200 to 
600. 
Further examples of suitable crosslinking agents are diallylamine, divinyl 
ketone, divinylsulphone and diallylmelamine. 
Surprisingly, water-soluble crosslinking agents, such as, for example, 
derivatives of acrylic or methacrylic acid, such as, for example, 
N,N'-methylene-bis-acrylamide, N,N'-methylene-bis-methacrylamide, 
N,N'-methylene-bis-(N-hydroxymethyl-methacrylamide), 
N,N'-bis-(methacryloyl)-aminoacetic acid, N,N'-bis-(acryloyl)-aminoacetic 
acid, 1,2-bis-(acrylamido)-1,2-dihydroxy-ethane, 
1,2-bis-(methacrylamido)-1,2-dihydroxy-ethane, 
1,2-bis-(N-hydroxymethyl-methacrylamido)-1,2-dihydroxy-ethane, 
1,2-bis-(N-methoxymethyl-methacrylamido)-1,2-dimethoxy-ethane, 
1,6-bis-(acrylamido)hexane, 1,6-bis-(methacrylamido)-hexane, 
2-methyl-1,4-bis-(acrylamido)-butane ("isovalerilydene-bis-acrylamide"), 
2-methyl-1,4-bis-(methacrylamido)-butane 
("isovalerilydene-bis-methacrylamide") and diacrylates and dimethacrylates 
of ethylene glycol, diethylene glycol and polyglycols 200 to 600, in 
combination with the abovementioned crosslinking agents of the formulae 
IV, V and VI, can also be used. 
Combinations of two or more crosslinking agents are also advantageous, for 
example of N,N'-methylene-bis-acrylamide/N,N-bis-(acryloyl)-aminoacetic 
acid; N,N'-methylene-bis-acrylamide/isovalerilydene-bis-acrylamide; and 
N,N'-methylene-bis-acrylamide/ethylene glycol 1,2-bis-(ethenephosphonate). 
Preferred crosslinking agent combinations can contain not only 
N,N'-methylene-bis-acrylamide and/or N,N'-methylene-bis-methacrylamide as 
a crosslinking agent component, but also the diacrylates and/or 
dimethacrylates of ethylene glycol, diethylene glycol or polyethylene 
glycols 200 to 600, or N,N',N"-tris-(2-acryloyloxyethyl) isocyanurate or 
N,N',N"-tris-(2-methacryloyloxyethyl) isocyanurate, trimethylolpropane 
triacrylate, trimethylolpropane trimethacrylate, pentaerythritol 
trimethacrylate, pentaerythritol triacrylate, butane-1,4-diol 
dimethacrylate,butane-1,4-diol diacrylate, hexane-1,6-diol diacrylate and 
hexane-1,6-diol dimethacrylate with N,N'-methylene-bis-acrylamide and/or 
N,N'-methylene-bis-methacrylamide. 
However, suitable n-valent crosslinking agents are also those compounds 
which contain only one or two polymerisable olefinic double bonds in the 
molecule but which, on the basis of secondary reactions, can additionally 
link (n-1) or (n-2) polymer chains with one another. Examples of such 
crosslinking agents are silanes containing alkoxy groups, in which the 
alkoxy groups are intermediately hydrlysed to Si--OH groups in an aqueous 
medium. Two silanol groups of this type then link two chains, by 
condensation and formation of a siloxane bond Si--O--Si. Examples of 
suitable crosslinking agents of this type are the organosilicon compounds 
described below, where these contain 1 or 2 olefinic double bonds and 
(n-1) or (n-2) alkoxy groups. 
Examples of suitable N-vinyl-amides of the general formula I are 
N-vinyl-N-formamide, N-vinyl-acetamide, N-vinyl-N-methylacetamide, 
N-vinyl-N-methyl-formamide, N-vinyl-N-ethyl-acetamide, 
N-vinyl-propionamide, N-vinyl-N-methyl-propionamide, 
N-vinyl-N-ethyl-propionamide, N-vinyl-butyramide, 
N-vinyl-N-methyl-butyramide and N-vinyl-N-ethyl-butyramide. 
N-Vinyl-formamide is particularly suitable, and N-vinyl-N-methyl-acetamide 
is especially suitable. The N-vinyl-amides of the general formula I 
incorporate into the copolymer according to the invention units of the 
general formula VII 
##STR3## 
wherein R.sup.1 and R.sup.2 have the meanings already given. 
Of the polymerisable organosilicon or organoboron compounds, the 
polymerisable organosilicon compounds are preferred. Examples of suitable 
polymerisable organosilicon compounds are silanes, siloxanes and 
silanzanes containing polymerisable olefinic groups. 
Examples of suitable polymerisable organosilicon and organoboron compounds 
are 3-(trimethoxy-silyl)-propyl acrylate or methacrylate, 
3-(triethoxy-silyl)-propyl acrylate or methacrylate, 
3-(tri(methoxyethoxy)-silyl)-propyl acrylate or methacrylate, 
3-(tri(methoxyethoxyethoxy)-silyl)-propyl acrylate or methacrylate, 
3-(di-(methoxy)-methyl-silyl)-propyl acrylate or methacrylate, 
3-(di-(ethoxy)-ethyl-silyl)-propyl acrylate or methacrylate, 
vinyl-tri-ethoxy-silane, vinyl-tri-methoxy-silane, 
vinyl-tri-allyloxysilane, allyl-tri-allyloxy-silane, 
vinyl-methyl-di-ethoxy-silane, vinyl-methyl-di-methoxy-silane, 
vinyl-tri-acetoxy-silane, vinyl-tri-(methoxyethoxy)-silane, 
1,3-di-vinyl-1,1,3,3-tetra-methyl-di-siloxane, 
1,3-di-vinyl-1,1,3,3,-tetra-methyl-disilazane, CH.sub.2 
.dbd.CH--COO--(CH.sub.2).sub.3 --(Si--(CH.sub.3).sub.p 
--Si(CH.sub.3).sub.2 --(CH.sub.3).sub.2 --O--CO--CH.dbd.CH.sub.2, CH.sub.2 
.dbd.C(CH.sub.3)--COO--(CH.sub.2).sub.3 --(Si(CH.sub.3).sub.2 --O).sub.p 
--Si(CH.sub.3).sub.2 --(CH.sub.3).sub.2 --O--CO--C(CH.sub.3).dbd.CH.sub.2, 
wherein p denotes a number from 1 to 20, in particular a number from 1 to 
10, CH.sub.2 .dbd.CH--CH.sub.2 --NH--SiH(CH.sub.3)--N(CH.sub.2 
CH.dbd.CH.sub.2)--SiH(CH.sub.3)--NH--CH.sub.2 --CH.dbd.CH.sub.2, triallyl 
borate and trimethallyl borate. The polymerisable organosilicon or 
organoboron compounds can, if the preconditions for this exist, also be 
used as n-valent crosslinking agents, or simultaneously as polymerisable 
organosilicon or organoboron compounds and crosslinking agents. 
Other suitable polymerisable compounds are those which do not belong to any 
of the abovementioned groups and have only one polymerisable olefinic 
group in the molecule, and which can be incorporated in a small amount 
into the copolymer without substantially altering its properties, thus, 
for example, .beta.-hydroxyethyl acrylate, .beta.-hydroxyethyl 
methacrylate, styrene, acrylonitrile and methacrylonitrile. 
The porous, bead-like copolymers according to the invention are prepared by 
bead polymerisation of 75 to 99.9% by weight of one or more pyridyl, 
quinolyl, isoquinolyl or pyrazinyl compounds containing a polymersible 
olefinic group, 0.1 to 25% by weight of one or more n-valent crosslinking 
agents and 0 to 25% by weight of one or more polymerisable organosilicon 
or organoboron compounds, and, based on 100% by weight of the sum of the 
abovementioned compounds, 5 to 350% by weight of one or more 
N-vinyl-amides of the formula I and 0 to 40% by weight of one or more 
other polymerisable compounds, n having the abovementioned meaning and it 
being possible for the pyridyl, quinolyl, isoquniolyl or pyrazinyl 
compound(s) also to be substituted, as already mentioned. 
Preferably, 80 to 99% by weight of one or more pyridyl, quinolyl, 
isoquinolyl or pyrazinyl compounds containing a polymerisable olefinic 
group, 1 to 20% by weight of one or more n-valent crosslinking agents and 
0 to 19% by weight of one or more polymerisable organosilicon and/or 
organoboron compounds, and, based on 100% of the sum of the abovementioned 
compounds, 10 to 250% by weight of one or more N-vinyl-amides of the 
general formula I and 0 to 25% by weight of units of another polymerisable 
compound or several such compounds, are employed in the copolymerisation. 
Very particularly preferably, no compounds from the group of other 
polymerisable compounds and/or 0.1 to 10% by weight of one or more 
polymerisable organoboron and/or organosilicon compounds are employed in 
the copolymerisation. 
Of the pyridyl, quinolyl, isoquinolyl or pyrazinyl compounds, the pyridyl 
compounds are preferably used, in particular vinyl-pyridines and 
particularly preferably 4-vinyl-pyridine. Up to 50% by weight of the 
pyridyl, quinolyl, isoquinolyl or pyrazinyl compound used in the 
copolymerisation can be replaced by one or more of the already mentioned 
heterocyclic 5-membered ring compounds with a polymerisable olefinic group 
and at least one protonatable nitrogen atom, in particular by 
1-vinyl-imidazole. 
The polymerisable monomers can as a rule be used here in their commercially 
available form, that is to say without prior purification. 
The copolymerisation is carried out by the bead polymerisation process 
(compare, for example, Houben-Weyl: Methoden der organischen Chemie 
(Methods of Organic Chemistry), 4th edition, Volume 14, 1 (1961), 
Makromolekulare Stoffe (Macromolecular Substances), Part 1, page 406 et 
seq.). In the bead polymerisation, the monomer mixture to be polymerised 
is as a rule broken down to the desired bead size in water or another 
liquid in which the monomers and the copolymer formed are isoluble, by 
mechanical stirring or shaking, preferably also under the action of one or 
more suitable dispersing agents, and is then copolymerised. The 
copolymerisation is triggered off in a manner which is known per se, for 
example by UV light, high-energy radiation or, as a rule, by an initiator 
which is soluble in the monomer mixture and supplies free radicals. 
Examples of suitable initiators are benzoyl peroxide, tert.-butyl 
hydroperoxide, cymene peroxide, methyl ethyl ketone peroxide, lauroyl 
peroxide, tert.-butyl perbenzoate, tert.-butyl diperphthalate, 
azodiisobutyronitrile, 2,2'-azobis-(2,4-dimethylvaleronitrile), 
2-phenyl-azo-2,4-dimethyl-4-methoxy-valeronitrile, 
2-cyano-2-propyl-azo-formamide, azodiisobutyramide and dimethyl, diethyl 
or dibutyl azobis-methylvalerate. Based on the amount of monomer 
(including the crosslinking agent), about 0.01 to 2% by weight, preferably 
0.1 to 1% by weight, of initiator is used. 
Dispersing agents which are used are water-soluble or water-solubilised 
naturally occurring substances, in particular carbohydrates and proteins, 
for example solubilised starch, methyl starch, methylcellulose or other 
cellulose ethers, methylhydroxypropylcellulose, cellulose glycolate and 
furthermore cholesterol, saponin, size, tragacanth and the like, or 
water-soluble high molecular weight synthetic emulsifiers, such as, for 
example, polyvinyl alcohol, polyacrylates or polymethacrylates, in amounts 
of 0.05 to 3% by weight, preferably 0.1 to 1% by weight, based on the 
amount of water present. 
It is advantageous to carry out the bead polymerisation in the presence of 
salts, such as, for example, sodium chloride or sodium nitrite, but in 
particular sodium formate, the salts being dissolved in the aqueous phase. 
It is furthmore advantageous to carry out the polymerisation in the 
absence of oxygen. This can be effected, for example, in a known manner by 
flushing with or passing through an inert gas, such as, for example, 
nitrogen. The bead polymerisation is usually carried out at temperatures 
from 45.degree. to 95.degree. C., preferably 55.degree. to 85.degree. C., 
and has as a rule ended after 0.3 to 3 hours. When the polymerisation has 
ended, the resulting bead-like copolymer is separated off, washed with 
water or an organic solvent and dried. 
The crosslinked copolymer according to the invention is in the form of 
porous beads, the diameter of which can be varied as desired in the range 
from about 2 to 0.04 mm by choosing the preparation conditions. Under 
given preparation conditions, beads with a narrow diameter spectrum are 
obtained. The copolymer according to the invention is, in particular, in 
the form of beads with a diameter of 0.02 to 0.2 mm, preferably 0.02 to 
0.1 mm, and is outstandingly suitable as a sorbent, in particular as a 
sorbent for acid substances from solvents. Acid substances in the context 
of the present invention are understood as meaning those substances of the 
general formula HA which can dissociate into LmH.sup.+ and an acid radical 
A.sup.- in a solvent of the general formula Lm (as a rule water or a 
water-containing solvent mixture). Examples of such acid substances are 
carboxylic acids, sulphonic acids, mineral acids, thiocarboxylic acids, 
phenols, thiophenols, mercapstans, acid imides and acid sulphimides. The 
acid organic substances mentioned can also be substituted and/or contain 
several identical or different acid groups in the molecule. 
Examples of suitable aliphatic and aromatic mono-, di- and poly-carboxylic 
acids, hydroxycarboxylic acids and ketocarboxylic acids are formic acid, 
acetic acid, propionic acid, n-butyric acid, i-butyric acid, n-valeric 
acid, trimethylacetic acid, caproic acid, n-heptylic acid, caprylic acid, 
capric acid, pelargonic acid, stearic acid, tallow fatty acid, 
fluoroacetic acid, chloroacetic acid, bromoacetic acid, iodoacetic acid, 
dichloroacetic acid, 2-chloropropionic acid, glycollic acid, lactic acid, 
methoxyacetic acid, thioglycollic acid, cyanoacetic acid, glyoxylic acid, 
malonic acid, acrylic acid, methacrylic acid, vinylacetic acid, 
phenylacetic acid, oxalic acid, succinic acid, glutaric acid, adipic acid, 
maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic 
acid, citric acid, malic acid, benzilic acid, aconitic acid, trimesic 
acid, benzoic acid, cinnamic acid, mandelic acid, tartaric acid, salicylic 
acid, acetoacetic acid, hydroxybenzoic acid, gallic acid and 
dihydroxybenzoic acid. 6-Aminopenicillanic acid and 7-aminocephalosporanic 
acid, for example, are also suitable. 
Examples of suitable mineral acids are sulphuric acid, phosphoric acid, 
phosphorous acid and hydrochloric acid. 
The copolymers according to the invention are also particularly suitable 
for the sorption of sulphonic acids, such as, for example, 
benzenesulphonic acid or naphthalene-1- or -2-sulphonic acid or 
naphthalene- or benzene-di- or -poly-sulphonic acids, and in particular 
also for the sorption of substituted sulphonic acids, for example of the 
benzene, naphthalene and anthraquinone series, such as are used in some 
cases in the manufacture of dyestuffs, in particular azo dyestuffs. Such 
sulphonic acids can be, for example, mono-, di- or tri-sulphonic acids and 
can be mono- or poly-substituted, for example by hydroxyl, amino, 
carboxyl, halogen, nitro or alkyl with 1 to 4 C atoms. Such sulphonic 
acids are known in some cases in the dyestuff industry under their trivial 
or discoverer names or under alpha-numerical designations (="Letter 
acids"). However, such sulphonic acids are given under their systematic 
names in the following selection of examples of suitable sulphonic acids: 
3-methyl-benzenesulphonic acid, benzene-1,3-disulphonic acid, 
methylbenzene-2,4-disulphonic acid, 2,4-dimethyl-benzenesulphonic acid, 
2,5-dimethyl-benzenesulphonic acid, 
2,6-dimethyl-4-tert.-butyl-benzenesulphonic acid, hydrindene-5-sulphonic 
acid, benzaldehyde-2,4-disulphonic acid, 4-chloro-benzenesulphonic acid, 
2,5 -dichloro-benzenesulphonic acid, 2-amino-benzensulphonic acid, 
3-amino-benzenesulphonic acid, aminobenzene-2,5-disulphonic acid, 
1,3-diaminobenzene-4-sulphonic acid, 1,3-diaminobenzene-4,6-disulphonic 
acid, 1,4-diaminobenzene-2,5-disulphonic acid, 
2-amino-5-methyl-benzenesulphonic acid, 
2-amino-3,5-dimethyl-benzenesulphonic acid, 2-amino-4-sulphobenzoic acid, 
2-amino-5-sulphobenzoic acid, 2-isobutylamino-5-sulphobenzoic acid, 
2-hydroxy-5-sulphobenzoic acid, 2-aminophenyl-4-sulphonic acid, 
3-amino-4-methoxy-benzenesulphonic acid, 2-aminophenol-4,6-disulphonic 
acid, 2-amino-5-chlorobenzenesulphonic acid, 
3-amino-4-chlorobenzenesulphonic acid, 
2-amino-4,5-dichlorobenzenesulphonic acid, 
4-amino-2,5-dichlorobenzenesulphonic acid, 
2-amino-5-chloro-4-methylbenzenesulphonic acid, 
3-amino-5-chloro-4-methylbenzenesulphonic acid, 
4-amino-5-chloro-3-methylbenzenesulphonic acid, 
5-amino-4-chloro-3-methylbenzenesulphonic acid, anthraquinone-1-sulphonic 
acid, anthraquinone-2-sulphonic acid, anthraquinone-1,5-or 
-1,8-disulphonic acid, anthraquinone-2,6- or -2,7-disulphonic acid, 2-, 
4-, 5- or 7-hydroxy-naphthalene-1-sulphonic acid, 6- or 
7-hydroxy-naphthalene-2-sulphonic acid, 4- or 
7-hydroxy-naphthalene-1,5-disulphonic acid, 4- or 
8-hydroxy-naphthalene-1,6-disulphonic acid, 
7-hydroxy-naphthalene-1,3-disulphonic acid, 3-, 4-or 
5-hydroxy-naphthalene-2,7-disulphonic acid, 
4-hydroxy-naphthalene-2,5-disulphonic acid, 
6-hydroxy-naphthalene-1,4-disulphonic acid, 
6-hydroxy-naphthalene-1,7-disulphonic acid, 2-, 4-, 5-, 6-, 7- or 
8-amino-naphthalene-1-sulphonic acid, 4-, 5-, 6-, 7- or 
8-amino-naphthalene-2-sulphonic acid, 6- or 
7-amino-naphthalene-1,3-disulphonic acid, 3- or 
4-amino-naphthalene-1,5-disulphonic acid, 4- or 
8-amino-naphthalene-1,6-disulphonic acid, 
4-amino-naphthalene-1,7-disulphonic acid, 
4-amino-naphthalene-2,6-disulphonic acid, 1-, 3- or 
4-amino-naphthalene-2,5-disulphonic acid, 
8-amino-naphthalene-1,3,6-trisulphonic acid, 
7-amino-naphthalene-1,3,5-trisulphonic acid, 
4-amino-naphthalene-1,5,7-trisulphonic acid, 
4-amino-naphthalene-2,5,7-trisulphonic acid, 4-amino-3- or 
-5-hydroxy-naphthalene-1-sulphonic acid, 6-, 7- or 
8-amino-4-hydroxynaphthalene-2-sulphonic acid, 2- or 
4-amino-5-hydroxy-naphthalene-1,7-disulphonic acid, 
4-amino-5-hydroxy-naphthalene-1,3-disulphonic acid, 3- or 
4-amino-5-hydroxy-naphthalene-2,7-disulphonic acid, 4,6- or 
6,7-dihydroxy-naphthalene-2-sulphonic acid, naphthalene-1,5-, -1,6-, 
-2,7-, -2,5-, -3,6- or -2,6-disulphonic acid, naphthalene-1,5,7- or 
-2,5,7-trisulphonic acid, 4-hydroxy-naphthalene-2,5,7-trisulphonic acid, 
4,5-dihydroxy-naphthalene-2,7-disulphonic acid and 
4-hydroxy-7-phenylamino-naphthalene-2-sulphonic acid. 
Acid salts of sulphonic acids, in particular acid sodium or ammonium salts, 
such as, for example, the Na salt of 6,7-dihydroxy-naphthalene-2-sulphonic 
acid, so-called G salt (Na salt of 6-hydroxy-naphthalene-2,4-disulphonic 
acid) and so-called R salt (Na salt of 
6-hydroxy-naphthalene-2,7-disulphonic acid) can also be sorbed. 
Other compounds which are suitable are: thiophenol, m-thiocresol, 
2-bromothio-p-cresol, ethanethiol, phenylmethanethiol, 1,4-butanedithiol, 
4-mercapto-2-pyridine-carboxylic acid, 2,3-dimercapto-succinic acid, 
dithioacetic acid, thioacetic O-acid, thioacetic S-acid, phthalimide, 
succinimide and benzenesulphimide. 
In the presence of mineral acids, sulphonic acids are preferentially sorbed 
by the copolymers according to the invention. The copolymers according to 
the invention are also suitable for the selective sorption of heavy metal 
ions, such as, for example, zinc, copper or mercury ions, from aqueous 
solutions, in particular also from extremely dilute aqueous solutions. The 
copolymers according to the invention are preferably suitable for the 
sorption of carboxylic acids, in particular from their aqueous solutions. 
In the sorption of carboxylic acids, the copolymers according to the 
invention have an at least 100% higher sorption capacity than the 
exchangers according to German Pat. No. C2-3,043,766, and at the same time 
a lower swelling capacity in solvents. The sorption is carried out in a 
manner which is known per se. As a rule, the column or fixed bed method is 
used, in which the sorbent is filled into a column, through which the 
solvent containing one or more acid substances then flows until the 
capacity of the exchanger is exhausted. Desorption of the sorbed acid 
substances is then likewise carried out in a manner which is known per se, 
thus, for example, with alkalis or, preferably, with the aid of organic 
solvents, such as, for example, an alcohol, such as methanol, ethanol, 
i-propanol or n-butanol, a ketone, such as acetone, methyl ethyl ketone or 
diethyl ketone, an ester, such as methyl or ethyl acetate, acetic acid 
ethylglycol ester or acetic acid ethyldiglycol ester, or an ether, such 
as, for example, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether 
or ethylene glycol diethyl ether. The desorbed acid substances can be put 
to use elsewhere. 
The sorption and desorption of acid substances with the aid of polymers 
according to the invention can also be carried out by other known sorption 
processes, such as, for example, by a continuous process with a moving 
bed, by the fluidised bed method or by batchwise operation. 
The heavy metal ions are likewise sorbed on the adsorber resins according 
to the invention and desorbed in a manner which is known per se. 
For example, the sorption of acid substances and, in particular, the 
desorption of acid substances by means of organic solvents is improved in 
the case of the copolymers according to the invention by a content of one 
or more N-vinyl-amides of the formula I. This improvement is particularly 
considerable with di- and poly-carboxylic acids, with aldehyde- and 
keto-carboxylic acids, and with higher contents of one or more 
N-vinyl-amides of the formula I. 
The percentages given in the examples which follow are percentages by 
weight.

EXAMPLE 1 
(a) 50 g of 4-vinyl-pyridine, 5 g of N-vinyl-N-methyl-acetamide and 5 g of 
pentaerythritol triacrylate are dissolved together with 0.22 g of 
dibenzoyl peroxide, and are dissolved, whilst passing through nitrogen and 
stirring. The resulting monomer mixture is then introduced into a solution 
of 300 ml of water, 37.5 g of sodium formate and 37.5 g of a 1% strength 
aqueous hydroxyethylcellulose solution, with stirring. The mixture is then 
heated, with continuous stirring and while passing through nitrogen, the 
polymerisation starting at 60.degree. C. Polymerisation is brought to 
completion at 80.degree. C. in the course of 1 hour. The resulting highly 
crosslinked porous bead-like copolymer is washed with water and dried. 
The yield is 54 g (about 90% of theory). 
(b) An equally good polymer with a porous and crosslinked structure is 
obtained if 5 g of pentaerythritol trimethacrylate are used instead of 
pentaerythritol triacrylate. 
In this example and in the following examples, the commercial product 
"Tylose H 30 000 yp" from Hoechst AG, Frankfurt am Main 80, is used for 
the preparation of the hydroxyethylcellulose solution. 
EXAMPLE 2 
87.5 g of 4-vinyl-pyridine, 22.5 g of N-vinyl-N-methylacetamide and 10 g of 
trimethylolpropane trimethacrylate are stirred together with 0.44 g of 
dibenzoyl peroxide, the mixture is introduced into a solution of 600 ml of 
water, 75 g of sodium formate and 75 g of a 1% strength aqueous 
hydroxyethylcellulose solution, while continuously passing through 
nitrogen and continuously stirring the mixture is warmed to 60.degree. to 
65.degree. C., whereupon the copolymerisation starts, and the 
polymerisation is brought to completion in the course of 1 hour. The 
resulting bead-like copolymer has a porous structure and is washed with 
water and dried. 
The yield is 105 g. 
EXAMPLE 3 
(a) 195 g of 4-vinyl-pyridine, 80 g of N-vinyl-formamide, 25 g of 
trimethylolpropane triacrylate and 1.1 g of dibenzoyl peroxide are 
dissolved at room temperature and the solution is added to a solution of 
1,500 ml of water, 187.5 g of sodium formate and 187.5 g of a 1% strength 
hydroxyethylcellulose solution, while continuously passing through 
nitrogen and stirring. The mixture is then heated to 65.degree. to 
70.degree. C. and the polymerisation is brought to completion in the 
course of 2 hours. The resulting porous bead-like copolymer is separated 
off, washed with methanol and dried. The yield is 285 g. 
(b) A porous bead-like copolymer with an equally good surface structure is 
obtained if, instead of 195 g of 4-vinyl-pyridine, the same amount of 
2-vinyl-pyridine is used. 
EXAMPLE 4 
25 g of 4-vinyl-pyridine, 25 g of N-vinyl-N-methylacetamide, 10 g of 
trimethylolpropane triacrylate and 0.176 g of dibenzoyl peroxide are 
dissolved at room temperature, the solution is added to a solution of 300 
ml of water, 37.5 g of sodium formate and 37.5 g of a 1% strength 
hydroxyethylcellulose solution, with continuous stirring, the mixture is 
warmed to 60.degree. to 65.degree. C. and the polymerisation is brought to 
completion in the course of 2 hours. The bead-like copolymer formed, with 
a well-structured porous surface, is washed with methanol and dried. The 
yield is 58 g. 
A porous bead-like copolymer of the same surface structure is obtained if 
the stated amount of 4-vinyl-pyridine is replaced by 
2-vinyl-6-methylpyridine. 
EXAMPLE 5 
(a) 45 g of 4-vinyl-pyridine, 5 g of 
1,7-bis-(3-hydroxypropyl)-1,1,3,3,5,5,7,7-octamethyltetrasiloxane 
bis-acrylate and 10 g of N-vinyl-formamide are dissolved together with 
0.22 g of dibenzoyl peroxide and the solution is added to a solution of 
300 ml of water, 37.5 g of sodium formate and 37.5 g of a 1% strength 
aqueous hydroxyethylcellulose solution, while continuously passing through 
nitrogen and stirring. The mixture is then heated to 70.degree. C. and 
polymerisation is carried out for 1 hour. The resulting copolymer is 
washed with water and then digested with methanol and separated off. The 
yield is 55 g. 
(b) An equally good, highly crosslinked copolymer is obtained if, instead 
of 1,7-bis-(3-hydroxypropyl)-1,1,3,3,5,5,7,7-octamethyltetrasiloxane 
bis-acrylate, the same amount of 3-triethoxysilylpropyl methacrylate is 
used. 
EXAMPLE 6 
(a) 22 g of 4-vinylpyridine, 33 g of N-vinyl-N-methyl-acetamide and 5 g of 
triallyl borate are dissolved together with 0.22 g of dibenzoyl peroxide 
and the solution is added to a solution of 300 ml of water, 37.5 g of 
sodium formate and 37.5 g of a 1% strength aqueous hydroxyethylcellulose 
solution, while continuously passing through nitrogen and continuously 
stirring. The mixture is then heated to 60.degree. C. and polymerisation 
is carried out for 1 hour. The resulting porous bead-like copolymer is 
separated off, washed with methanol and dried. The yield is 57.5 g. 
(b) Equally good porous bead-like copolymers are obtained if, instead of 5 
g of triallyl borate, the same amount of trimethallyl borate is used. 
EXAMPLE 7 
40 g of 4-vinyl-quinoline, 15 g of N-vinyl-formamide and 5 g of 
pentaerythritol triacrylate are dissolved together with 0.22 g of 
dibenzoyl peroxide, the solution is added to 500 ml of toluene, while 
passing through nitrogen and stirring, and copolymerisation is carried out 
at 80.degree. C. The highly crosslinked porous bead-like copolymer is 
washed with toluene and dried. The yield is 55 g. 
A product with equally good properties is obtained if the stated amount of 
40 g of 4-vinyl-quinoline is replaced by 4-vinylisoquinoline. 
EXAMPLE 8 
49.5 g of 4-vinyl-pyridine, 5.5 g of N-vinyl-formamide, 5 g of 
N-vinyl-N-methylacetamide and 5 g of trimethylolpropane trimethacrylate 
are dissolved together with 0.22 g of dibenzoyl peroxide and the solution 
is added to a solution of 300 ml of water, 37.5 g of sodium formate and 
37.5 g of a 1% strength aqueous hydroxyethylcellulose solution, while 
passing through nitrogen and continuously stirring. The mixture is then 
heated to 70.degree. to 75.degree. C. and polymerisation is brought to 
completion in the course of 1 hour. The resulting porous bead-like polymer 
has a porous surface structure and is filtered off with suction, digested 
with methanol and dried. 
The yield is: 60 g. 
A product with an equally good surface structure is obtained if, instead of 
5 g of N-vinyl-N-methylacetamide, 5 g of N-vinyl-N-ethylacetamide are 
used. 
EXAMPLE 9 
To determine the adsorption capacity, 50 g of copolymer are packed into a 
glass column with an internal diameter of 25 mm, and a 1% strength aqueous 
D-lactic acid solution is passed through at a rate of 1.8 bed 
volumes/hour, until the runnings are acid. For desorption of the lactic 
acid, 650 ml of methanol are passed through the column at a rate of 1.8 
bed volumes/hour and the D-lactic acid in the eluate is determined 
quantitatively by an enzymatic method with lactate dehydrogenase. 
On using various copolymers, the adsorption values shown in the following 
table are obtained. 
______________________________________ 
Copolymer Capacity in g of D-lactic acid/ 
according to Example 
100 g of copolymer 
______________________________________ 
1a 22 
3a 25 
5a 74 
5b 76 
6a 54 
1 of German Patent C2-3,043,766 
8 
______________________________________ 
In the same manner, using the new copolymers according to the invention, it 
is possible to sorb, for example, formic acid, acetic acid, propionic 
acid, n-butyric acid, i-butyric acid, valeric acid, caproic acid, capric 
acid, glycollic acid, malic acid, malonic acid, succinic acid, oxalic 
acid, glutaric acid, adipic acid, maleic acid, fumaric acid, citric acid, 
tricarballylic acid, tartaric acid, glyoxylic acid and phenols, and then 
to elute these compounds again with solvents, such as, for example, 
acetone, methanol, ethyl acetate, tetrahydrofuran, dioxane or 
dimethoxyethane. 
EXAMPLE 10 
2 g of the product according to Example 5b are suspended in a 
water/methanol mixture (volume ratio 1:1) and the suspension is introduced 
into a glass column with a diameter of 1.5 cm. The filling is washed with 
500 ml of water. 
An aqueous solution of ZnCl.sub.2 with a pH value of 2 and containing 
10.sup.-6 g/ml is then introduced onto the column and the Zn.sup.++ ion 
content is determined in the individual fractions of the runnings. In the 
first 1,280 ml of the runnings, the content of Zn.sup.++ ions is below 
10.sup.-8 g/ml, and then increases to 1.2.times.10.sup.-7 g/ml. 
EXAMPLE 11 
49.5 g of 4-vinyl-pyridine, 40.5 g of N-vinyl-imidazole, 20 g of 
N-vinyl-N-methylacetamide and 10 g of trimethylolpropane triacrylate, 
together with 0.44 g of dibenzoyl peroxide are added, after being 
dissolved, to a solution of 600 ml of water, 75 g of sodium formate and 75 
g of a 1% strength aqueous hydroxyethylcellulose solution, while passing 
through nitrogen and continuously stirring. The mixture is then heated to 
70.degree. to 71.degree. C. and the polymerisation is brought to 
completion in the course of 1 hour. 
The resulting bead-like polymer has a porous surface structure. It is 
separated off, washed with methanol and dried. The yield is 115 g.