CA1121944A

CA1121944A - Polar polymeric sorbentbased on glycidyl esters for gas and liquid chromatography

Info

Publication number: CA1121944A
Application number: CA000295280A
Authority: CA
Inventors: Jaromir Lukas; Jaroslav Kalal; Frantisek Svec
Original assignee: Czech Academy of Sciences CAS
Current assignee: Czech Academy of Sciences CAS
Priority date: 1977-01-19
Filing date: 1978-01-19
Publication date: 1982-04-13
Also published as: DE2801858A1; FR2377826A1; FR2377826B1; DE2801858C2; JPS5390991A; CS188619B1; US4340483A; GB1577270A

Abstract

ABSTRACT OF THE DISCLOSURE

A polar polymeric adsorbent based on glycidyl esters, which consists of a macroporous copolymer containing 3-70 percent of polymerized monomeric units containing epoxy groups, selected from the group comprising glycidyl methacrylate and glycidyl acrylate, 97-30 percent of a crosslinking agent selected from the group comprising alkylene diacrylate, alkylene dimethacrylate, hydroxyalkylene diacrylate, hydroxyalkylene dimethacrylate, where the alkylene contains 1-6 carbon atoms, and divinylbenzene, and optionaily, up to 30 percent of polymer-ized monomeric units containing nitrile groups, selected from the group comprising acrylonitrile and methacrylonitrile. The polymeric adsorbent of the invention is particularly suitable for use in gas and liquid chromatography.

Description

The present invention is concerned with a polar poly-meric adsorbent based on glycidyl esters and suitable for use in gas and liquid chromatography, which enables through its properties the chromatographic separation of mixtures of various compounds.
In the early seventies, polymeric adsorbents were in-troduced for application in gas chromatography in connection with the advancement in production of macroporous polymers.
They are particularly suitable for use in the gas-solid chromatography. Most o~ the commercially available adsorbents of this type are produced starting from styrene-divinyl-benzen~
copolymers. Its substance is, however, close to non-polar anchored phases, which means that their polarity is relatively low. The polarity measure of anchored phases is expressed in the literature, as a rule, in terms of Rohrschneider constants (J.Chromatog.22, 6, 1966), i.e. by 0.01 times the difference between the retention indices of benzene (x), ethanol (y), methyl ethyl ketone (z), nitromethane (u), and pyridine (s) on squalane and the retention indices of these compounds on the given anchored phase. Because the relation of the retention indices to the anchored phase is not completely correct in the case of gas-solid chromatography, the retention indices on squalane were substituted by the indices of the same standards measured at 150C on the non-polar sorbent Carbopack B and the calculated modified values of Rohrschneider constants were expressed as x', yl~ z~, u', and s', respectively.
One o~ the most polar adsorbents at ~resent is Porapak T, which has the Rohrschneider constants x' = 1.30, y' = 2.90, z' = 2.21, u' = 3.44 (s' was not determined) and is a homopolymer of ethylene dimethacrylate. The polarity extent of some polymeric adsorbents may be extended by subsequent modification, nevertheless it is too small and the adsorbents , ~
~'~ ' 19~4 can be used above all for the separation of non-polar compounds.
The application of adsorbents based on hydroxyalkyl methacrylate or acrylate gels, according to Czechoslovak Patent N. 159 990, and on their modified products renders broader prospects. The Rohrschneider constants for these adsorbents attain the following values: x' = 2.29, y' =
3.53, z' = 2.75, u' = 4.09 (s' was not determined). An enhance-- ment of polarity may be also achieved by the ternary copolymeriza-tion o polar monomers, such as hydroxyalkyl acrylates or metha-crylates, with a non-polar monomer of the alkyl acrylate or methacrylate type and a crosslinking agent, according to the Czechoslovak Patent N. 175 156. The adsorbent prepared in this way has the Rohrschneider constants x' = 1.73, y' = 3.24, z' = 2.63, u' = 3.95, and s' = 3.54.
However, the above mentioned materials d~o not possess a sufficient polarity for the separation of some mixtures.
The present invention therefore relates to a polar polymeric adsorbent based on glycidyl esters which is suitable for use in gas and liquid chromatography and consists of a macroporous copolymer containing 3-70 % of polymerized monomeric units containing epoxy groups, selected from the group comprising glycidyl methacrylate (i.e. 2,3-epoxypropyl methacrylate) and glycidyl acrylate, ~7 - 30% of a crosslinking agent selected from the group comprising alkylene diacrylate, alkylene dimethacrylate, hydroxyalkylene dimethacrylate, hydroxyalkyl diacrylate, where the alkylene contains 1-6 carbon atoms, and divinylbenzene, and, optionally, up to 30% of polymerized monomeric units containing nitrile groups, selected from the group comprising acrylonitrile and methacrylonitrile.
The in-~ention also comtemplates the above polar polymeric adsorbent in which the epoxy groups of the macroporous copolymer are modified by a nucleophilic agent, such as water, ~;Z19'~4 alcohols, carboxylic acids and their derivatives, ammonia, primary and secondary arnines, mercapto cornpounds, and acrylonitrile.
The materials according to the invention are used as packings for columns in the gas and liquid chromatography.
hey are prepared with a broad range of porosity and polari-ty by a suspension radical polymerization, e.g. according to the Czechoslovak Patent N. 175 112. Their convenient adsorp-tion properties are documented by the linear shape of adsorption isotherms and the corresponding peak sy~metry of separated compounds. The mechanical and volume stability with changing medium and temperature is exceptionally good, Also, the retention times of the compounds separated on the adsorbents according to the invention are substantially shorter in compari-son with known adsorbents and the separations can be generally carried out at lower temperatures.
The invention will now be illustrated, with reference to the following non-restrictive examples.
Example 1 An adsorbent was prepared in a polymerization vessel of 1 litre volume from 600 ml of a 1% aqueous solution of polyvinylpyrrolidone and a mixture consisting of 9.6 g of dodecanol, 98.8 g of cyclohexanol, ~9.2 y glycidyl methacrylate, 32,8 g of ethylene dimethacrylate, and 0.80 g of 2,2' - azobis (isobutyronitrile). The ba-tch was bubbled through with a stream of nitrogen for 15 minutes, the reactor was then closed and aggitation was set off t250 r.p.m.). After five minutes of stirring, the mixture was heated to 70C. The copolymeriza-tion proceeded at this temperature for 2 hours and at 80C for further 6 hours. After the reaction had been completed, the product was separated and washed by decantation with ethanol (twice), benzene(twice), and again with ethanol (twice).

11;~1~44 Eor chromatographic purpose, the copolymer was extracted with ethanol for 4 hours, dried in a vacuum oven, and fractionated. The fraction having a particle size of 150-200 um was used for packing of a glass column having a length of 120 cm and an inner diameter of 0.3 cm. The packing was first conditioned at 170C in a nitrogen stream at a rate of 20 ml/min. for 24 hours. The value of modified Rohrschneider indices of the adsorbent were : x' = 2.02, y' = 3.65, z' = 2.96, ,u' = 4.75, s' = 3.93. The separation of 0.2 ul of a mixture of C7-C12 alkane~ was carried out at a temperature of 175C

and an argon through-flow of 24 ml/min.
Retention times of the individual hydrocarbons were as follows:
heptane 1.28 min, octane 1.58 min, nonane 3.15 min, decane 5.15 min, undecane (b.p~ 194C) 8.45 min, dodecane (b.p.
214.5C) 14.30 min.
Example 2 The separation of 0.15 ul of alcohols on the adsorbent according to Example 1 was carried Ollt at a temperature of 140C
and an argon through-flow of 25 ml/min. Retention times of the individual components were: methanol 1.4~ min, et~anol

2.64 min, isopropyl alcohol 3.40 min, tert-butanol 4.29 min, propanol 4.96 min, isobutanol 7.98 min, butanol 9,87 min, 3-methylbutanol (b.p.132C) 17.30 min, pentanol (b.p.137.9C~

20.00 min.
Example 3 A successfull separation of a mixture of methyl to hexyl esters of acetic acid on the adsorbent according to ~- Example 1 was carried out at a temperature of 175C and an ar~on through-1Ow of 25 ml/min. Retention times of the

3~ individual esters were: methyl acetate 1.38 min, ethyl acetate 1.93 min, tert-butyl acetate 2.75 min, butyl acetate

4.43 min, pentyl acetate 7.56 min, hexyl acetate (p.p. 16a.2C) ;~;
p..,~
~. ~

94~
12.21 min.
E~ample 4 A mixture (0.1 ul) of vinyl hexyl ether, hexanol, cyclohexanol, and 2-methylcyclohexanol was injected into a column packed with the adsorbent according to Exarnple 1, the temperature of the column was 175C and the -through-flow of the carrier gas was 25 ml/min. The following retention times of the individual components are the evidence of successfull gaschromatographic separation: vinyl hexyl ether 5.12 min, hexanol 9.45 min, cyelohexanol 12.48 min, 2-methylcyclohexanol (b.p. 166C~ 15.83 min.
Example 5 A mixture of cyclopentanone, cyclohexanone and 2-methylcyclohexanone was separated under the same conditions as in Example 4. The retention times were: cyclopentanone 6.87 min, cyclohexanone 12.33 min and 2-methylcyclohexanone 14.65 min~
Example 6 A mixture (0.2,ul) of compounds with different functional groups and having very similar boiling points was injected into a column packed with the material according to Example 1 at a temperature of 115C and a through-flow of argon of 25 ml/min. The retention times of the components were as folows: ethanol (b.p. 78.4C) 5.89 min, l-chlorobutane (b.p. 77.9C) 9,32 min, ethyl acetate (b.p. 77.1C) 11.55 min, methyl ethyl ketone (b.p. 79.6C) 13.15 min.
Example 7 A copolymer was prepared in the same way as in Example 1 with the distinction that the weights of monomer and crosslinking agent were 24.6 g of glycidyl methacrylate and 57.4 g of et'nylene dimethacrylate. The copolymer was extracted, used for packing o~ a column (120 cm x 0.3 cm), and conditioned in the sarne way as in Example 1. The relatively lower polarity predeterminates this adsorbent above all for the separation of compounds which differ in the number of free ~-electrons (olefins, cycloolefins, aromatic hydrocarbons), but it can be used also for the separation of other types of compounds. The modified Rohrschneider constants had the follow-ing values: x' = 1.05, y' = 2~37, z' = 1.89, u' = 2.92 (s' was not determined). A mixture (0.1 ul) of cyclohexane, cyclohexene and benzene was separated at a temperature of 132C and a through-flow of argon of 25 ml/min. The retention of these compounds was affected by the number of free ~-electrons in the molecule: cyclohexane (b.p. 80-81C) 12.33 min, cyclohexene (b.p. 83.3C) 14.42 min, benzene (b.p. 80.1C) 18.23 min.
Example 8 A successfull separation of 0.1 ul of a mixture of cycloalkanes and equally substituted aromatic hydrocarbons was carried out similarly as in Example 7, at a temperature of 172C and a through-flow of argon of 25 ml/min. The retention times of the individual components were as follows: cyclohexane

5.70 min, benzene 7.91 min, methylcyclohexane 10.23 min, toluene 16.72 min, ethylcyclohexane 22.6 min, ethylbenzene 34.42 min.
Example 9 An adsorbent was prepared by the same procedure as in Example 1, with the distinction that the monomer mixture consisted of 32.8 g of glycidyl methacrylate, 16.4 g of acetonitrile, and 32.8 g of ethylene dimethacrylate. Also the preparation of the terpolymer for its chromatographic application, packing of the column which had the same parameters, and conditioning of the packing were carried out in the same way. This adsorbent exhibited a thermal stability up to 270C
and had a strong polar character. The values of the modified Rohrschneider indices were as follows: x' = 3.62, y' = 4.64, 9 ~

z' = 4 43, u' = 7.00, s' = 5 97 A mixture o~ 0.2 ,ul of polar compounds was separated a-t 108C and a through-flow of argon of 25 ml/min. The individual compounds had the following retention times: diethyl ether 2.76 min, methanol 4.39 min, ethanol 7.14 min, acetone 8.37 min, methyl ethyl ketone 16.90 min.
Example 10 A mixture of carboxylic acids (0.3 ~ul) was separated on a column packed with the material according to Example 9:
the temperature of the column was 170C and the through-flow of argon was 25 ml/min. The retention times were: acetic acid 5.57 min, propionic acid 7.79 min, isobutyric acid 9,02 min, butyric acid 11.45 min, valeric acid (b.p. 187C) 18.37 min.
Example 11 The copolymer according to Example 1 was modified by hydrolysis and subsequen-t cyanoethylation in the following way: 50 g of the copolymer was stirred in a threefold volume of 1 N aqueous sulfuric acid and the hydrolysis was carried out at 90C for 1 hour, 5 g of the hydrolyzed sample was shaken with 15 ml of acrylonitrile and 15 ml of 9 N sodium hydroxide solution at 25C for 4 hours. The product was then washed with water until the alkaline reaction ceased and dried in a vacuum oven. A colurnn of 1 m length and 0.35 mm inner diameter was packed with the modified copolymer and conditioned at a tempera-ture of 180C in a stream of nitrogen at a rate of 20 ml/min for hours. This adsorbent had also a strongly polar character and broad application possibilities. The values of the modified Rohrschneider constants were as follows: x' = 2.71, y' = 5.14, z' = 4,29, u' = 7.13, s' = 5.81. A mixture (0.1/ul) of chlorinated hydrocarbons was separated at a colu~ temperature of 150C, injection temperature of 190C, and through-flow of nitrogen of 30 ml/min. The retention times of the indi~idual colnpoullds were : l-chlorobuta~e 1.10 min, 1,3-dichlorobutane 4.08 min, 1,4-dichlorobutane 7.08 min.
Example 12 A mixture (0.1 ul) of trichlorobenzenes was separated using the adsorbent according to Example 11 at a column ternpera-ture of 190C, injection temperature of 230C, and through-Ælow of nitrogen of 30 rnl/min. The individual isomers had -the following retention times : l,3,5-trichlorobenzene 3.52 min, 1~2,4-triehlorobenzene 5.21 min, 1,2,3-trichlorobenzene (b.p.
218-219C~ 6.80 min.
Example 13 The separation of C2-C5 carboxylie acids was earried out under the following conditions: the adsorbant according to Example 11, column temperature 165C, injeetion temperaturQ
220~, throuyh-flow of nitrogen 30 ml/min, injected volume 0.15 ul. The retention times obtained, acetie aeid 5.20 min, propionie aeid 6.74 min, butyrie aeid 4.19 min, valerie aeid 13.90 min.
Example 14 A suecessfull gas~ehromatographie separation of a mixture of compounds with different functional groups was carried out using the adsorbent according to Æxample 11, under the following conditions: column temperature 90C, injection temperature 130C, injected volume 0.1 ~1, through-flow of nitrogen 30 ml/min. The individual compounds left the column in the following order: l-chlorobutane 4.36 min, ethanol 6.48 min, butyraldehyde 7.60 min, methyl ethyl ketone 10.70 min.
Example lS
The polymerie adsorbent aceording to Example 1 was modified by heating in a 0.5 N aqueous solution of perchlorie aeid for 2 hours at 90CO It was then separated, washed until the aeid reaetion eeasec3, extraeted with ethanol for 4 hours and dried. Eor its application, it was packed into a colur~
and conditioned. The values of the modified Rohrschneider indices were: x' = 2.93, y' = 5.24, z' = 4.64, u' = 5.52, (s' was not determined). The adsorbent was successfully employed for the separation of polar compounds by the gas-chromatographic method.
Example 16 The polymer according to Example 1 was heated with a 50 % solution of 2-hydroxyethylamine at 60C for 6 hours.
1~ Then it was washed with water, extracted with ethanol, dried, and packed into a column. The adsorbent exhibited the following values of the modified Rohrschneider indices: x' = 3.23, y' =

6.12, z' = 4.74, u' = 6.83, s' = 6.53 and was also success-fully used for the separation of polar compounds by gas-chromatography.
Example 17 A copolymer of glycidyl methacrylate - ethylene dimethacrylate was prepared according to ~xample 1, with the distinction that the moncmer mixture consisted of 70 %~of glycidyi methacrylate and 30% of ethylene dimethacrylate and that the mixture was agitated during polymerization more vigorously (700 r.p.m.). The fraction having a particle size of 15-20,um was separated from the resulting product, thoroughly dried and modified in the following way: 5 g of the copolymer was dispersed in 20 ml of stearoyl chloride and shaken at 20C
for 4 hours, at 70C for 1.5 hours, and at 80C for 6 hours.
The product after stearoylation contained 5.60 % of chlorine.
A column of 200 x 8 mm was packed with this adsorbent and used for the separation of a mixture of aromatic hydrocarbons (benzene, diphenyl, anthracene, chrysene, and benzopyrene) by liquid chromatography.
Other adsorbents were prepared analogously to Example 1 from nlonomer mixtures and under conditions given in the following examples (in Examples 18-24, the monomer mixtures and r.p.m. were different).
Example 1~
Glycidyl acrylate 24.6 g, 2-hydroxypropylene diacrylate 32.8 g, methacrylonitrile 24.6 g; 300 r.p.m.
Example 19 Glycidyl acrylate 20.5 g, 2,3,4,5-tetrahydroxyhexamethy-lene dimethacrylate 61.5 g; 1500 r.p.m.
Example 20 Glycidyl methacrylate 49.2 g, 2,3-dihydroxytetramethy-lene dimethacrylate 32.~ g; 350 r.p.m.
Examp-e 21 Glycidyl methacrylate 8.2 g, tetramethylene diacrylate 73.7 g; 250 r.p.m.
Example 22 Glycidyl methacrylate 16.4 g, divinylbenzene 65.6 g;
1800 r.p.m.
Example 23 2Q Glycidyl methacrylate 2.5 g, ethylene dimethacrylate 79.5 g; 250 r.p.m.
Example 24 Glycidyl methacrylate 41.0 g, ethylene dime-thacrylate 32.8 g: acrylonitrile 4.1 g; 250 r.p.m.
Example 25 The copolymer prepared according to Example 1 was modified in the following way: into a vessel equipped with a tight closure, containing 15 g of the copolymer, 10 g of dimethylamine was distilled under intense cooling. The vessel was sealed and its content was heated to 60C for 2 hours.
After cooling, the vessel was opened, unreacted a~ine volatilized, and the adsorbent, containing 2.23 mmol amino groups per g, was ll~lg~4 packed into a column~ After conditionning in a stream of nitrogen at 180C, the gas chromatographic separation of mixtures comprising alcohols, hydrocarbons and esters of carboxylic acids were carried out.
Example 26 An adsorbent containing SH-groups was prepared from the copolymer formed according to Example 22 (fraction having a particle size of 5 - 20 ~m~ by the procedure described in Example 25, with the distinction that hydrogen sulfide was distilled instead of amine into the reaction vessel. It ~as packed into a column and used for the separation of a mixture of natural compounds by liquid chromatography.
Example 27 The copolymer according to Example 1 (20 g) was placed on a glass flask equipped with a reflux condenser and a stirrer and 50 ml of a~ueous ethylene diamine solution (75 % w/w) was added. The mixture was stirred at a temperature of 80C ~or 6 hours, the solid phase was collected on a fritted glass filter and washed with O.l N NaOH (1 litre) for 4 hours and with water until the alkaline reaction disappeared. After drying, the product was packed into a column, conditioned, and used for the gas-chromatographic separation of a mixture consisting of polar and nonpolar compounds. The adsorbent was thermally stable up to 210C. The values of the modified Rohrschneider indices were as follows: x' = 2.89, y' = 6.40, u' = 6.98, s' = 6.54, z' was not determined.
Example 28 An adsorbent containing 2.20 mmol nitrogen/g was prepared analogously to Example 27, by reaction with methylamine instead of ethylenediamine. It was thermally stable up to 200C
and was employed for the gas-chromatographic separation of mixtures of compounds. The values of the modified Rohrschneider L9~

indices were as follows: x' = 2.13, y' = 4.67, z' = 3.52, u' = 4.84, s' = 4.80.
Example 29 The polymer prepared according to Example 17 (the fraction having a particle size of 5-20 ~m, was reacted with dodecylamine in the same procedure as in Example 27 and used as the packing for the separation of nonpolar hydrocarbons by liquid chromatography.
Example 30 The polymer prepared according to Example 19 was modified by the same procedure as in Example 27 using 2-mercapto-ethanol as the substrate. The product was employed for the separation of natural compounds by the liquid chromatography method.
Example 31 An adsorbent was prepared in the same way as in Example 1, with the distinction that the monomer mixture consisted of 24.8 g of glycidyl methacrylate, 24.6 g of acrylonitrile, and 32.8 g of ethylene dimethacrylate. The product after polymerization was prepared for application by screening, packing of a column and conditioning as in Example 1. A mixture of diols (0.1 ul) was separated on the column at 195C and a through-flow of nitrogen of 27 ml/min. The retention times of the individual components were as follows:
l-butanol 1.25 min, ethylene glycol monomethacrylate 1.80 min, diethylene glycol diethyl ether 3.66 min, 2,3-butanediol 5.80 min, ethylene glycol 6.50 min, 1 t 3-propanediol 11.50 min, benzyl-alcohol 15.76 min.
Example 32 The separation of trichlorobenzene isomers was carried out on the same packing and under the same conditions as in Example 31. The retention times of the individual components - 12 ~

9~4 were as follows: 1,3,5-trichlorobenzene 5.10 min, 1,2,4-tri-chlorobenzene 6.94 min, 1,2,3-trichlorobenzene 9.66 min.
Exar,lple 33 The adsorbent prepared according to Example 31, with the distinction that methacrylonitrile was used instead of acrylonitrile, was subjected to acid hydrolysis by heating to 80C in 0 5 M sulfuric acid for 2 hours. The product was washed with water until the acidic reaction ceased and dried.
After packing into a column and conditioning~ The separation of 0.15 ul of a mixture of carboxylic acids was carried out at a temperature of 170C and a through-flow of nitrogen of 27 ml/min. The retention times of the individual components were as follows: acetic acid 7.22 min, propionic acid 10.42 min, valeric acid 27.02 min.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A polar polymeric adsorbent based on glycidyl esters and suitable for use in gas and liquid chromatography, which consists of a macroporous copolymer containing 3-70 percent of polymerized monomeric units containing epoxy groups, selected from the group comprising glycidyl methacrylate and glycidyl acrylate, 97-30 percent of a crosslinking agent selected from the group comprising alkylene diacrylate, alkylene dimetha-crylate, hydroxyalkylene diacrylate, hydroxyalkylene dime-thacrylate, where the alkylene contains 1-6 carbon atoms, and divinylbenzene , and optionally, up to 30 percent of polymerized monomeric units containing nitrile groups, selected from the group comprising acrylonitrile and methacrylonitrile.

2. A polar polymeric adsorbent according to Claim 1, wherein the epoxy groups of the macroporous copolymer are modified by a nucleophilic agent.

3. A polar polymeric adsorbent according to claim 2, wherein the nucleophilic agent is selected from the group comprising water , alcohols, carboxylic acids and their derivatives, ammonia, primary and secondary amines, mercapto compounds and acrylonitrile.