DE1944756B2 - PROCESS FOR THE MANUFACTURING OF MALEIN ITACON OR ACONIT ACID ANHYDRIDE HOMOPOLYMERIZATES - Google Patents

Description

The invention relates to a process for the homopolymerization of maleic, itaconic and aconitic anhydride.

It is known that maleic, itaconic and aconitic anhydride can be homopolymerized. the Homopolymers and their derivatives, e.g. B. the water-soluble salts are used as builders in detergents, as additives for other polymer systems, as textile auxiliaries and for surface treatment used by metals.

In U.S. Patent 3,359,246 there is one method for the preparation of homopolymers of maleic anhydride and its derivatives.

Acetyl peroxide is used as the polymerization initiator. Under these conditions one obtains a Homopolymer in yields of up to 90%. By S.D. Hamann, Aust. J. Chem., 1967, vol. 20, Pp. 605 to 609 describe the polymerization of maleic anhydride under high pressure. In this Publication is reported to be difficult to homopolymerize maleic anhydride start is and that special polymerization methods are required to achieve satisfactory results obtain. The same difficulties arise with the homopolymerization of itaconic and aconitic anhydride on.

The use of acetyl peroxide as a polymerization initiator in the process according to US Pat. No. 3,359,246 has considerable disadvantages. Acetyl peroxide is sensitive to impact and can detonate if improperly handled. Another disadvantage is that acetyl peroxide is currently only commercially available as a solution in dimethyl phthalate. The end product of the polymerization is contaminated by the dimethyl phthalate. To separate off the dimethyl phthalate, the polymer must be extracted with an organic solvent. When working on a small scale, this does not provide ^one difficulty in an industrial process, this method is cumbersome.

The use of high pressures to polymerize the anhydrides is part of an engineering process not desirable, since this requires special expensive devices.

The invention relates to a process for the preparation of maleic, itaconic or aconitic anhydride homopolymers with the help of acyl peroxides as polymerization initiators, which thereby is characterized in that the monomeric anhydride to at least its melting point in Heated presence of the initiator, one being a compound for maleic anhydride as initiator of the general formula I or II

O O

Il Il

CH-C-OO-C-R

Il.

CH-COCR ₁ or

O O

(I)

Il

CH - C - OO - H
CH-C-O-C-R

(Π)

for itaconic anhydride as initiator a compound of the general formula III or IV

GH ₂

O O

Il Il

c-c -00-c-R

ο ο

CH ₂ COCR

CH ₉

C-C-00-H
OO

-! CH ₂ -COCR (III) (IV)

and for aconitic anhydride as initiator, a compound of the general formula V, VI or VII

OO OO OO

CH - C - OO - C - R gh - c - O - C -: R CH - C - O - C - R

OO OO OO

CCOCR ₁ CC-OO-CR ₁ or CCOCR ₁

CH ₂ - C - OO - C - R ₂

(V)

CH ₂ -COCR ₂

(VI)

11 Il

CH ₂ -C-OO-CR ₂

(VII)

used in which R, R ₁ and R _{2 are} each aliphatic or cycloaliphatic radicals having 1 to 6 carbon atoms

litte input

or phenyl groups which are unsubstituted or by halogen atoms, nitro, cyano, methoxy or Ethoxy groups are substituted and optionally the anhydride homopolymer obtained with water saponified to the homopolymer of the free acid.

The mixed maleic, itaconic, or aconitic acyl peroxide initiator is preferably used in the process of the invention first made. For this purpose, the anhydride is first melted either in the presence or absence of a solvent. Hydrogen peroxide is then added to the melt. The hydrogen peroxide reacts immediately and practically quantitatively with the anhydride to form the corresponding peracid. This implementation takes the example of maleic anhydride as follows:

CH

CH

CH

00 —H

O + H ₂ O ₂

C-C-OH

O - 00 - Η f 2 / O
π c ^ r ± 3 ■ τ- * -CH, CH O OO O
Il CH-C /
O
\ Il
/ C Q Il
-C-CH ₃ - OH \ CH 0 - ^K c - c - C-CH, CH-C

O Ό

The peracid is then treated with an acylating agent added, usually a carboxylic acid anhydride. The acylating agent reacts with the Peracid to form a mixed maleic, itaconic or aconitic acyl peroxide. Exemplary the use of acetic anhydride as acylating agent and peroxymaleic acid proceeds Implementation as follows:

+ 2CH ₃ C-OH

Other carboxylic anhydrides that can be used as acylating agents are e.g. B. propionic acid, Hexanoic acid and cyclohexanecarboxylic acid anhydride. It can also be asymmetrical, i. H. mixed Carboxylic anhydrides can be used. Examples of these compounds are formic acid acetic anhydride, Benzoic acid-acetic anhydride, propionic acid-acetic anhydride and cyclohexanecarboxylic acid-acetic anhydride.

The carboxylic acid anhydrides suitable as acylating agents can either be unsubstituted or by Halogen atoms, nitro, cyano, methoxy or ethoxy groups can be substituted. Examples of substituted Carboxylic acid anhydrides are trifluoroacetic acid, trichloroacetic acid, Chloroacetic acid, p-nitrobenzoic acid

acid, cyanobenzoic and methoxybenzoic anhydride. Furthermore, the phenyl groups in the acylating agents can be replaced by lower aliphatic radicals be substituted with 1 to 6 carbon atoms. An example of these acylating agents is isopropylbenzoic acid acetic anhydride.

Ketene can also be used as an acylating agent in such amounts that 1 or 2 mol Ketene per mole of a maleic or itaconic acid peracid and 1 to 3 moles per mole of an aconite peracid are used will. When using z. B. 1 mole of ketene per mole of permaleic acid is obtained monoacetylated Product used as an initiator for the homopolymerization of maleic anhydride. This implementation proceeds as follows:

O
CH-C-OO

Il

CH - C - OH
O

+ CH ₂ = C =

Il

CH-C-OO-H

Il · ■■

C ^ OC / (-Ή3 OO

If 2 moles of ketene are used, a diacetylated product is obtained. This implementation takes place after following reaction equation:

CH - C - OO - H
CH - C - OH

Il ο

+ 2CH ₂ = C = O

O O

CH - C - OO - C - CH ₃

Il

CH CO - C CH ₃ OO

When performing the polymerization of maleic, itaconic or aconitic anhydride, the anhydride is melted in the presence of corresponding mixed maleic, itaconic or aconitic acyl peroxides and the reaction is carried out at temperatures between 65 and 95 ° C for maleic anhydride and at 70 to 10O ⁰ C for itaconic anhydride and carried out at 80 to 110 ⁰ C for aconitic anhydride. Since the polymerization is exothermic, heat should be dissipated at least during the initial reaction in order to keep the temperature in the specified range. Usually that is

Polymerization ended within 4 to 6 hours. The polymerization can be carried out in the presence or absence of a solvent. The solvent should not react with the peroxide initiator, the anhydride or the homopolymer. Examples of suitable solvents are benzene, chlorobenzene, o-dichlorobenzene and alkyl acetates, such as Butyl acetate and isopropyl acetate.

Normally, amounts of about 2 percent by weight of the initiator, based on the Weight of the monomer to start the reaction. However, larger quantities can also be used be used. Larger amounts are desirable in order to get the polymerization reaction going quickly set. The exact amount of initiator depends on the acyl radical used to make the peroxide is used.

In practice, the process of the invention can be carried out to obtain the necessary Amount of the monomer with or without a solvent in a reaction vessel submitted to the Reaction temperature heated and then hydrogen peroxide is added in such an amount that it is with part of the anhydride reacts. Usually the hydrogen peroxide is used in an amount of at least about 0.5 percent by weight, based on the anhydride used, is used. Of course larger amounts of hydrogen peroxide can also be used. Usually this is Amount not more than 2 percent by weight. The hydrogen peroxide reacts with a stoichiometric one Amount of anhydride with formation of the peracid. The peracid obtained does not itself act as a polymerization initiator. It also does not react with the unreacted anhydride. This is at least the stoichiometric amount of an acylating agent required for reaction with the peracid, and normally introduced a slight excess into the reaction mixture. The acylating agent settles with the peracid to form the mixed maleic, itaconic or aconitic acyl peroxide around. The mixed peroxide obtained then starts homopolymerization of the anhydride. at the polymerization of maleic anhydride can be obtained by the process of the invention Product have a molecular weight of 500 to 50,000. Usually has polymaleic anhydride a molecular weight of about 3,000 to 7,000. In the polymerization of itaconic or aconitic anhydride according to the process of the invention, the product may have a molecular weight of from 350 to 1,500,000.

The homopolymer is purified in a simple manner by heating the product under reduced pressure in order to separate off volatile compounds. The acids which correspond to the acylating agents which were used to prepare the mixed peroxides are suitable as volatile compounds. The homopolymers prepared by the process of the invention are easily soluble in water and organic solvents such as acetone, tetrahydrofuran, 1,2-dimethoxyethane, alkyl acetates, methyl ethyl ketone and dioxane. When the anhydride homopolymers are dissolved in water, they are converted into the corresponding homopolymers of the free acids. Metal salts can be prepared from the polycarboxylic acids obtained by customary methods. A simple process for the preparation of these salts consists in that the anhydride homopolymer is dissolved in water at about 100 ^° C., the aqueous solution obtained with a base, e.g. B. sodium hydroxide solution, neutralized to a pH of 10.0 and the resulting solution heated for 3 to 4 hours. The pH is then adjusted back to about 10.0. The alkali metal salt is obtained, which remains as a solid substance after the water has evaporated.

For example

In a 1 liter three-necked flask equipped with a stirrer and a reflux condenser is, 650 g of maleic anhydride are presented. The flask is placed in a water bath at 65 ° C heated until the maleic anhydride has melted. Then the agitator is started, and 7.0 g of 90% peroxide are added dropwise within 5 minutes. The reaction mixture is allowed to continue for another 10 minutes heated to 65 to 75 ° C, then 100 g of acetic anhydride are added. Shortly thereafter starts an exothermic polymerization reaction.

. The flask is cooled with cold water to keep the temperature of the reaction mixture at 75 to 95 ⁰ C. After about 2 hours of reaction, the reaction subsides and the cooling water is replaced by warm water in order to keep the temperature of the reaction mixture at 75 to 95 ° C. for a further 2 to 3 hours until the polymerization has ended. The flask is then evacuated and most of the acetic acid formed as a by-product is distilled off. The distillation is stopped as soon as the reaction mixture is very viscous. The raw, viscous product is then dissolved in about 21% hot water. This saponifies the maleic anhydride polymer to form polymaleic acid. Water is distilled off from the mixture under reduced pressure. 693 g of crude polymaleic acid remain. The yield is 90% of theory, based on the maleic anhydride used.

Comparative experiment

The example is repeated, but the 100 g acetic anhydride are not added. To After 6 hours of heating at 75 to 95 ° C, there is practically no polymerization. About 95% of the used Maleic anhydride is recovered as it is.

This experiment shows that permaleic acid, which is produced by reacting hydrogen peroxide with a Part of the maleic anhydride has formed, the polymerization of the maleic anhydride does not occur in Able to set gear.

^: Example2

The procedure of Example 1 is repeated, but 150 g of propionic anhydride are used in place which uses 100 g of acetic anhydride. The yield of polymaleic acid is 87% of theory.

B e i s ρ i e Γ 3

The procedure of example is repeated, but 150 g of benzoic anhydride are used instead which uses 100 g of acetic anhydride. The yield of polymaleic acid is 72% of theory.

Example 4

The procedure of Example 1 is repeated, but 150 g of cyclohexanecarboxylic anhydride are used used instead of 100 g acetic anhydride. The yield of polymaleic acid is 74% of the Theory.

Example5

The procedure of Example 1 is repeated, but 150 g of trichloroacetic anhydride are added Place of 100 g acetic anhydride used. The yield of polymaleic acid is 92% of theory.

B e i s ρ i e 1 6

The procedure of Example 1 is repeated, but 100 g of trifluoroacetic anhydride are added Place of 100 g acetic anhydride used. In this experiment, the temperature of the reaction mixture during the first 15 minutes Addition of the trifluoroacetic anhydride kept at 60 to 65 ° C. The anhydride boiling at 42 ° C boils under reflux. As soon as all of the trifluoroacetic anhydride has reacted, it forms in the reflux condenser no more condensate. The reaction mixture is then heated to 75 to 95.degree. To After 6 hours of reaction, the yield of polymaleic acid is 91% of theory.

Example7

In a 1 liter three-necked flask equipped with a stirrer and a reflux condenser is, 650 g of maleic anhydride are presented. The flask is heated in a hot water bath until the temperature of the maleic anhydride is about 65 ° C and the compound has completely melted is. The stirrer is then started and 7.0 g of 90% strength hydrogen peroxide are added dropwise. The reaction mixture is heated to 65 to 75 ° C. for a further 10 minutes, and then are 16 g of gaseous ketene initiated. The ketene is through a glass tube with an inner diameter of 6 mm at a flow rate of 0.01 mol / min for 38 minutes. nitrogen is passed through the reaction mixture to purge methane from the flask, which is a by-product arises during acetone pyrolysis. The reaction mixture is heated to 75 to 95 ° C. for 5 hours. The product is then isolated according to Example 1. 680 g of crude polymaleic acid are obtained. the The yield is 88.4% of theory.

If 8.0 g of ketene are used instead of 16 g, polymaleic acid is obtained in 88% yield.

Comparative experiment

If the experiment is repeated but no ketene is introduced, no polymerization takes place. Approximately 95% of the maleic anhydride used is recovered unchanged. The in situ generated Permaleic acid cannot initiate the polymerization of the anhydride. The mixed carboxylic acid-acetic anhydrides are used in place of acetic acid according to the procedure of Example Γ. The results are in Table I compiled:

Table I. Mixed things IO Benzoic acid acetic acid lot Poly-
malein yield Anhydride acylating agents ahhydride acid % Formic acid vinegar G g. i ₅ acid anhydride ....... Trichloroacetic acid vinegar 150 620 80.5 acid anhydride ...... m-chlorobenzoic acid 100 605 78.7 acetic anhydride .. Cyclohexanecarboxylic acid 150 696 90.4 acetic anhydride .. 150 676 87.8 150 610 79.2

B e i s ρ i e 1 9

25 g of itaconic anhydride are placed in a 100 ml three-necked flask equipped with a stirrer and a reflux condenser. The flask is heated in a water bath at 70 to 8O ⁰ C, is melted until all itaconic anhydride. The stirrer is then started and 10 drops of 90% hydrogen peroxide are added over the course of 5 minutes. The reaction mixture is heated to 75 to 80 ° C. for a further 30 minutes and then 5 ml of acetic anhydride are added. Shortly thereafter, an exothermic polymerization reaction begins. The flask is cooled with cold water to maintain the temperature of the reaction mixture at 95-110 ° C. After about 25 minutes of reaction, the polymerization reaction subsides and the flask is placed in a hot water bath in order to keep the temperature of the reaction mixture at about 100.degree. The polymerization has ended after a further 2 hours. The reaction mixture is dissolved in hot water, and acetic acid formed as a by-product and water are distilled off under reduced pressure. 28 g of polyitaconic acid are obtained as a pale yellow solid. The yield is 96.6% of theory.

Comparative experiment

The experiment is repeated, but no acetic anhydride is added. ^{After 6} hours of heating at 95 ° C., there is practically no polymerization. About 95% of the itaconic anhydride used is recovered unchanged.

This experiment shows that itaconic anhydride is polymerized by itaconic acid by reacting the hydrogen peroxide with part of the itaconic anhydride, not going is set.

. B e i s ρ iel 8

There are: · several mixed carboxylic acid anhydrides by reaction of the corresponding carboxylic acids with; jKeten according to the method of R. E. Du n, b a rund E.'C, G a r ν e n, Journal of American Society ,, VpI. 77 (1955), p. 4161.

Example 10

The procedure of Example 9 "is repeated, but instead of acetic anhydride equivalent amounts of the acid anhydrides listed in Table II were used. The yield of polyitaconic acid is also given in this table.

109 508/379

1 944 756 Be 10 1 13 9 i s ρ i e Table II

Acid anhydride Yield to
Polyitaconic acid
% Propionic anhydride
Benzoic anhydride
Cyclohexanecarboxylic anhydride ....
Trichloroacetic anhydride
Trifluoroacetic anhydride 94.3
91.0
92.0
97.0
. 97.0

B e i s ρ ie I 11

A 100 ml three-necked flask equipped with a stirrer and a reflux condenser is, is charged with 70 g of itaeonic anhydride and heated to about 75 ° C in a water bath heated until all of the itaconic anhydride has melted. Then the stirrer is started, and 1.0 g of 90% hydrogen peroxide is added dropwise. The reaction mixture is allowed to continue for another 10 minutes kept at 75 ° C, and then 2.5 g of gaseous ketene are introduced. The keten is through a glass tube with an inner diameter of 6 mm at a rate of 0.01 mol / min while 6 minutes initiated. The reaction mixture is stirred for a further 5 minutes, then it becomes nitrogen initiated as a by-product in the manufacture of the ketene by pyrolysis of acetone to displace formed methane. The reaction mixture is heated to 75 to 100 ° C. for 3 hours. The product is isolated according to Example 1. The yield is 78 g of crude polyitaconic acid, that is 96% of theory.

The experiment is repeated, but 1.3 g of ketene are used instead of 2.5 g. The polymerization runs smoothly, and polyitaconic acid is obtained in 94% yield.

Example 12

In a 10.0 ml three-necked flask equipped with a stirrer and a reflux condenser 25 g of aconitic anhydride are added. The flask is placed in a water bath at 80 to 85 ° C heated until the aconitic anhydride has melted. The stirrer is then started, and it 5 drops of 90% hydrogen peroxide are added dropwise within 5 minutes. The reaction mixture is heated to 80 to 85 ° C for a further 30 minutes and then treated with 3 ml of acetic anhydride. Shortly thereafter, an exothermic polymerization reaction begins. The flask is filled with cold Water cooled to keep the temperature of the reaction mixture at 90-110 ° C. After about After 25 minutes of conversion, the polymerization reaction subsides. The flask is in a hot water bath adjusted to the temperature of the reaction mixture for an additional 3 to 4 hours at about 100 ° C hold until the polymerization reaction is complete. The reaction mixture is then converted into dissolved in hot water, and the acetic acid formed as a by-product and the water are under distilled off under reduced pressure. The addition of water turns the polymer into polyaconitic acid saponified. 28 g of a pale yellow solid are obtained. The yield is 96% of theory.

Comparative experiment

The experiment is repeated without the addition of acetic anhydride. After heating for 6 hours At 95 ° C there is practically no polymerization. About 90% of the aconitic anhydride used are recovered unchanged. This experiment shows that peroxyaconitic acid, by reaction of hydrogen peroxide with part of the aconitic anhydride, the polymerization of aconitic anhydride does not start.

Example 14

Example 13 is repeated, but equivalent amounts of acetic anhydride are used. Several mixed carboxylic acid anhydrides are used as the acid anhydrides shown in Table IV by reacting the corresponding carboxylic acids. The yield of polyaconitic acid is anabolic acids made with ketene. Given these mixed.
Carboxylic acid anhydrides are used in place of acetic acid in the procedure of Example 9. labile IV
The results are summarized in Table III:

Table III

Mixed things lot Poly
itacon yield Anhydride acylating agents G acid
G Benzoic acid acetic acid anhydride 5.0 26.2 90 Formic acid vinegar acid anhydride 4.0 22.0 76 TricMoroacetic Acid acetic anhydride .. 8.0 27.0 93 rri-chlorobenzoic acid acetic anhydride .. 8.0 25.0 86 Cyclohexanecarboxylic acid acetic anhydride .. 7.0 25.6 88

Acid anhydride

Propionic anhydride

Benzoic anhydride

Cyclohexanecarboxylic anhydride Trichloroacetic anhydride ......

Trifluoroacetic anhydride

Yield of polyaconitic acid

91 87 88 94 95

A

Example 15 100 ml three-necked flask with

Equipped with a stirrer and a reflux condenser, 75 g of aconitic anhydride are charged and heated in a water bath to about 80 ° C until the aconitic anhydride has melted. After that, the The stirrer is started and 1.0 g of 90% strength hydrogen peroxide is added. The reaction mixture

is heated to 80 to 85 ° C for a further 10 minutes, and then 3.7 g of gaseous ketene are introduced at a flow rate of 0.01 mol / min, over 9 minutes. The reaction mixture is stirred for a further 5 minutes, then flushed with nitrogen and ^{heated to 80 to 100 °} C. for 4 hours. The reaction product is worked up according to Example 13. 80 g of crude polyaconitic acid are obtained. The yield is 92.5% of theory.

The experiment is repeated, but 2.0 g of ketene are used instead of 3.7 g. The polymerization runs smoothly and polyaconitic acid is obtained in 86% yield.

Example 16

Several mixed carboxylic acid anhydrides are produced by reacting the corresponding carboxylic acid made with keten. These mixed carboxylic acid-acetic anhydrides are used in place of acetic acid used as acylating agent according to Example 13. The results are summarized in Table V:

Table V

Mixed things
Anhydride acylating agents

Benzoic acid acetic acid

anhydride

Formic acid vinegar *

acid anhydride ......

Trichloroacetic acid

acetic anhydride ..
m-chlorobenzoic acid

acetic anhydride ..

Cyclohexanecarboxylic acid acetic anhydride ..

4.0
3.0
6.0
6.0
6.0

Polyaconitic acid

26.0 21.0 27.0 24.0 23.0

Yield *

90 73 94 84 80

30th

35

40

Claims (7)

Patent claims: 1. Process for the preparation of maleic, itaconic or aconitic anhydride homopolymers with the help of acyl peroxides as polymerization initiators, characterized in that that the monomeric anhydride is heated to at least its melting point in the presence of the initiator, maleic anhydride being used as initiator a compound of the general formula I or II O O Il ■ Il CH- C - OO - C - R CH COCR ₁ O O Il CH - C - OO - H Il ■ CH-C-O-C-R 55 60 65 for itaconic anhydride as initiator a compound of the general formula III or IV CH ₂ O O II II c - c - 00 - c - R O O Il Il O O C XV | (III) CH, (Π) C-C-OO-H OO Il Il CH ₂ -COCR (IV) and for aconitic anhydride as initiator, a compound of the general formula V, VI or VII O O Il Il v_ / \ JKJ v JtV O O Il. Il C C O - O Iv ^ O Il Il CH ₂ -C-OO-CR ₂ (V) O O Il Il CH-C-O-C-R O O Il · Il CC-OO-OO CR ₁ Il Il CH ₂ -COCR ₂ (VI) OO Il Il CH-C-O-C-R O O Il Il c c ο c Ri O CH ₂ -C-OO-CR ₂ (VII) used in which R, R ₁ ; and R _{2 are} each aliphatic or cycloaliphatic radicals with 1 to 6 carbon atoms or phenyl groups which are unsubstituted or substituted by halogen atoms, nitro, cyano, methoxy or ethoxy groups, and optionally the anhydride homopolymer obtained with water to form the homopolymer saponified free acid. 2. The method according to claim 1, characterized in that maleic anhydride at Tem- ίο temperatures from 65 to 95 ° C in the presence of at least about 2 percent by weight of the initiator polymerized. 3. The method according to claim 1 or 2, characterized in that maleic anhydride is ^{melted at a temperature of at least about 65 0} C, the melt is mixed with about 0.5 to 2 percent by weight hydrogen peroxide, then ketene or an acyl anhydride, the mixed anhydride to be produced corresponds to the general formula I or II, and the reaction mixture is heated ^{to temperatures of 65 to 75 ° C.} 4. The method according to claim 1, characterized in that itaconic anhydride is ^{polymerized at temperatures of 70 to 100 0} C in the presence of at least 2 percent by weight of the initiator. 5. The method according to claim 1 or 4, characterized in that itaconic ^{anhydride is melted at a temperature of at least about 70 0} C, the melt is mixed with about 0.5 to 2 percent by weight hydrogen peroxide, then ketene or an acyl anhydride, which is the compound to be prepared general formula III or IV corresponds to feeds and the reaction mixture heated to temperatures of 75 to 100 ⁰ C. 6. The method according to claim 1, characterized in that aconitic anhydride is ^{polymerized at temperatures of 80 to 110 0} C in the presence of at least 2 percent by weight of the initiator. 7. The method according to claim 1 or 6, characterized in that aconitic anhydride is ^{melted at a temperature of at least about 8O 0} C, the melt is mixed with about 0.5 to 2 percent by weight hydrogen peroxide, then ketene or an acyl anhydride, which is the compound to be prepared general formula V, VI or VII corresponds feeds and the reaction mixture heated to temperatures of 80 to 110 ⁰ C.