DE2124000A1 - Symmetrically substd monazo cpds - with terminal halo or hydroxy gps, used as polymsn initiators - Google Patents

Abstract

Title cpds. of formula: YAO-CO-C(R1)(R2)-N=N-C(R1)-(R2)-CO-OAY (where Y is OH or halogen esp. Cl; R1 is CH3; R2 is lower alkyl or cycloalkyl or cycloalkyl together with R1 and A is aliphatic hydrocarbon opt. contg. O as ether linkages) are prepd. by reacting pref. 1 mole of NC-C(R1)(R2)-N=N-C(R1)(R2)-CN with 2-20 moles of HOAY in the presence of acid, esp. HCl and under anhydrous condtns. They are used as water-sol. polymsn. initiators esp. for vinyl acetate monomers, terminal halogen and hydroxy gps. being readily introduced into the oligomer produced.

Description

Azo compounds with functional groups It has been found that symmetrically substituted azo compounds with functional groups of the formula I where Y is OH or halogen, preferably C1, R1 is methyl, R2 is lower alkyl or cycloalkyl or together with R1 is cycloalkyl, and A is an aliphatic hydrocarbon radical, which can optionally be interrupted by oxygen atoms in an ether bond, are valuable new azo initiators which, compared to the previously known compounds of this type have considerable advantages in various fields of application.

The new compounds can be prepared by using symmetrical azonitrile compounds of the formula II where R1 is methyl, R2 is lower alkyl or cycloalkyl or together with R1 is cycloalkyl, under anhydrous conditions in the presence of acids, preferably hydrogen chloride, with difunctional compounds of the formula III HO - A -) L III where Y is OH or halogen, preferably C1, and A denotes an aliphatic hydrocarbon radical which, if appropriate, is interrupted by oxygen atoms in an ether bond, converts and hydrolyzes the imidoester acid addition salts thus obtained.

The invention relates to the new, symmetrically substituted Azo compounds of the formula I, processes for their preparation and their use as free radical initiators in polymerization reactions.

The symmetrical azonitrile compounds to be used as starting material of formula II are known. They are usually used as initiators in polymerizations used.

Preferred azo compounds are those which are within the temperature range decay into radicals at a good rate from 60 - 1600C. The half-lives these azo compounds are known or can easily be determined by standard methods will. The half-life of the azo compounds to be used according to the invention should be within the specified temperature range for a maximum of 120 minutes.

The best known symmetrical azo compounds with nitrile end groups is azobisisobutyronitrile (AIBN), because of its easy technical accessibility is particularly preferred.

However, there are also a number of other azo compounds with Nitrile end groups known, e.g. B.

2,2'-azo-bis-2-methyl-butyronitrile 1,1'-azo-bis-cyclopentanecarbonitrile 1,1'-azo-bis-cyclohexanecarbonitrile 2,2'-azo-bis- (α-cyclopropylpropionitrile) 2,2'-azo-bis (α-cyclopentylpropionitrile) 2,2'-azo-bis (α-cyclohexylpropionitrile) In the azonitrile compounds of the formula II, R2 is an alkyl radical with a maximum of 4 Carbon atoms, preferably methyl or methyl.

The cycloalkyl radicals usually have no more than 6 carbon atoms, Cyclopropyl and cyclopentyluride cyclohexyl are preferred radicals.

The difunctional compounds of the formula III are aliphatic Compounds with at least 2 carbon atoms. The aliphatic chain can be straight or branched and also be interrupted by oxygen atoms in ether bonds. The chains lJf itzell about 2 - 20 carbon atoms, preferably about 2 - 6 carbon atoms, provided the chain between the functional groups has an aliphatic hydrocarbon structure owns. Examples include: ethylene chlorohydrin, ethylene glycol, propanediol (1,2 and 1,3), 1-chloropropan-3-ol, butanediol, pentanediol, hexanediol and the higher ones Homologues with up to 20 carbon atoms.

It is not absolutely necessary that the functional groups are arranged terminally, only these products are generally more easily accessible.

Among the compounds of the formula III, the chains of which are interrupted by ether oxygen, the most important are those which are derived from polyethylene oxides or glycols and from polypropylene oxides or glycols. These can be characterized by the formula IV.

where R = H or CH3 and m = 1-150, preferably 1-75.

Preferred compounds are diethylene glycol, triethylene glycol, tetraethylene glycol as well as the corresponding propylene glycols and the higher homologues. The most common Types of polyethylene oxides or glycols are those with medium molecular weights from 200, 300, 400, 600, 1000, 1500, 3000, 4000, 5000, 10,000 and 20,000. Polypropylene oxides or glycols are most easily available with average molecular weights of 250, 3000 and 4000.

Poly-tetra et} ly-lenoxides are also suitable, i.e. H. Telephony products of tetrahydrofuran (Tetramnethyleiiexid) which in different degrees of polymerization be available.

All known methods can be used for the implementation, those for the reaction of nitriles with alcohols to form imidoesters or their salts have been described. The reaction usually takes place in the presence of acid take place under anhydrous conditions. Preferred acids are hydrogen halides, especially hydrogen chloride and hydrogen bromide.

But concentrated sulfuric acid can also be used.

It is known that they are formed in this way under anhydrous conditions from nitriles and alcohols, the corresponding imido ester salts, z. B. in the present of hydrogen chloride the corresponding imidoester hydrochloride (when using the corresponding hemisulphates are formed from sulfuric acid).

As a rule, it is advisable to carry out the reaction in an organic, solvents that are resistant to the acids used, are free of hydroxyl groups and anhydrous perform. Preferred solvents are e.g. B. benzene, toluene, xylene, chloroform, Dichloromethane, carbon tetrachloride, nitrobenzene, dioxane or diethyl ether. It however, the difunctional reaction components of the formula III can also be used as solvents serve as long as they are in liquid form.

So is z. B. ethylene chlorohydrin is a suitable solvent.

The reaction temperatures are generally between -50 and + 500C, preferably between -10 and + 200C; the response times vary approximately between 10 and 70 hours.

fThe normal procedure for carrying out the procedure is as follows: that under anhydrous conditions (humidity and moisture (no reagents) I-ICl gas in the mixture of 1 mole of egg r-ior3 azonibrils of formula II and 2 - 20 Moles of bifunctional Compound of the formula III - optionally in the presence of solvents - initiates. At least 2 moles of H0l should be supplied will; however, it is easier to introduce HUI gas until the mixture is saturated. The resulting imidoester hydrochloride is not required for the further reaction to be isolated.

As a rule, it is advantageous to use the difunctional compounds of To use formula III in excess; this ensures that largely only one OH group reacts while the other functional group (OH or halogen) acts as terminal substituent is retained. This is the reason why it is used of the liquid difunctional derivatives of the formula III as solvents in many Cases of particular advantage.

The imido ester salts are then hydrolyzed, the easiest way by treatment with an excess of water or, preferably, ice water. Included the corresponding esters are formed in a manner known per se; the imino group becomes exchanged for oxygen.

The resulting esters of formula I are in a conventional manner from the Reaction mixture isolated. The higher molecular ones, some of which are produced in small quantities Products can usually be processed using conventional methods, e.g. B. by washing out or by gel chromatography. Usually interfering with of technical use, these small amounts of by-products are not, as they have the same end groups as the main products. Their separation is therefore not always necessary.

Particularly preferred compounds of the formula 1 are those in which the radical A is a straight or branched, aliphatic hydrocarbon radical having 2-20, preferably 2-6, carbon atoms. In addition, the azo compounds of the formula I are also of importance in which A is a radical of the formula where R is hydrogen or methyl and m is 1-149, preferably 1-75.

The following azo compounds may also be mentioned in detail: ß-chloroethyl azo-bis-isobutyric acid Azo-bis-isobutyric acid ß-hydroxylethyl ester Azo-bis-isobutyric acid (2-hydroxypropyl) ester Azo-bis-isobutyric acid (4-hydroxy-butyl) ester Azo-bis-isobutyric acid (6-hydroxy-hexyl) ester Azo-bis-isobutyric acid triethylene glycol ester Azo-bis-isobutyric acid polyethylene glycol ester Azo-bis-isobutyric acid polypropylene glycol esters and the corresponding esters of 2,2'-azo-bis-2-methylbutyric acid, 1,1'-azo-bis-cyclopentanecarboxylic acid, 1,1'-azo-bis-cyclohexanecarboxylic acid, of 2,2'-azo-bis- (a-cyclopropyl) -propionic acid, of 2,2'-azo-bis- (α-cyclopentyl) -propionic acid uiid of 2,2'-azo-bis (α-cyclohexyl) propionic acid.

In this way, titanium receives new azo initiators with special properties. Were azo initiators with hydroxyl or halogen groups as terminal substituents not yet readily accessible. If so far these substituents on the Chain ends the oligomers or polymers produced with the aid of azo initiators are desirable found a conversion of suitable end groups after the reaction of the initiators with the monomers instead. Such transformations then run into difficulties, if the oligomers or polymers are built up from monomers that are still reactive are, such as B. vinyl acetate. This problem is due to the new initiators with terminal OH or halogen substituents solved in a simple manner.

The new azo initiators according to the invention are of particular advantage if you telechelen them according to the method of German patent application P 20 30 589 Reacts oligomers. In addition, many of the new compounds are water-soluble azo initiators for the initiation of PolymerisatisnsreaktionenX They are here in about the same Type and amount used as the previously used azo initiators.

Example 1 a) 32.8 g of AIBN and 200 ml of ethylene chlorohydrin are initially at +1000 and then at 0 ° 0 saturated with dry HCl gas and stirred at 0 ° 0 for 60 h. Then 150 ml of dry ether are added and the mixture is 20 h stored at - 200C. The precipitated azo-bis-isobutyric acid (B-chloroethyl) imidoester hydrochloride is filtered off, washed twice with 100 ml of cold ether each time and put in a separating funnel decomposed with 500 ml of ice water.

The separated oil is separated off after 45 minutes and the aqueous Phase is exhaustively extracted with ether. Oil and ether extracts are combined and dried with magnesium sulfate. The ether is at 3000 on the rotary evaporator removed.

By recrystallization in low-boiling petroleum ether (40 - 450G) with addition of seed crystals, azo-bisisobutyric acid-ß-chloroethyl ester is used as obtained white, crystalline product.

Mp .: 30 ° O Analysis: C H N Oil calc .: 44.05 6.16 8.56 21.67 found: 43.56 6.08 8.37 21.90 In an analogous manner, using 2,2'-azobis-2-methyl-butyronitrile is obtained the 2,2'-azo-bis-2-methyl-butyric acid-B-chloroethyl ester or from 2,2'-aeo-bis (a-cyclopentyl) carbonitrile 2.2 1-azo-bis (a-cyclopentyl) propionic acid-B-chloroethyl ester.

b) In a 500 ml three-necked flask with stirrer, reflux condenser, internal thermometer and drop capillary, 100 ml of degassed toluene are brought to an internal temperature of 102-106 ° C brought.

16.4 g (0.05 mol) of azo-bis-isobutyric acid-ß-chloroethyl ester and 25 g (0.25 mol) of methyl methacrylate are dissolved in 150 ml of toluene, degassed and with pumped into the flask at a rate of about 40 ml / h. The pump comes with Rinsed 40 ml of toluene. The mixture is left to react for a further 30 minutes. The toluene and volatile components are next at 1000C bath temperature and then removed in a high vacuum.

36 g of an oligomeric compound of the formula are obtained A Mn value of 620 is found by vapor pressure osmometry; this corresponds to an average degree of polymerization of nt- = 2.9.

Example 2 16.5 g (0.1 mol) of AIBN, 225 g (1.5 mol) of triethylene glycol and 250 ml of benzene are saturated with HCl gas at 8 ° C. The reaction mixture is Stirring further overnight at 0 ° C. and then in a separating funnel with 100 g of ice offset. The colorless benzene phase is separated off. The yellow, aqueous phase is mixed with 150 ml of water and extracted successively with 100, 50 and 50 ml of C11013. The chloroform phases are then shaken with aqueous sodium bicarbonate solution washed neutral and dried. The chloroform is used on a rotary evaporator 3000, last in the oil pump vacuum, removed.

The obtained azo-bis [isobutyric acid triethylene glycol ester] is a pale yellow colored oil that is soluble in water.

Analysis: a H N calc .: 51.5 8.15 6.0 found: 51.5 8.16 6.2 If one uses 1,1'-azo-bis-cyclopentanecarbonitrile instead of AIBN, then 1,1'-azo-bis-cyclopentanecarboxylic acid triethylene glycol ester is obtained, and from?, l'-azo-bia-cyclohexalcarbonitrile, the 1,1'-azo-bis-cyclohexanecarboxylic acid triethylene glycol ester is formed.

Example 3 A solution of 16.4 g of AIBN and 100 g of hexanediol (1.6) in 200 ml of chloroform is saturated with HCl at OOC.

The hexanediol which precipitates out on cooling the solution goes in the course the reaction in solution. The reaction mixture is stirred overnight at -500 and then placed in a shaking funnel. 20 g of ice are added and the CHCl phase is separated and the aqueous phase was washed with 50 ml of CHCl3. The chloroform phases become neutral washed and dried and the chloroform is removed on a rotary evaporator. 15 g of azo-bis-isobutyric acid (6-hydroxy-hexyl) ester are obtained.

Mn (theor.) = 402 Mn (geS.) = 425 Analysis: C H N calc .: 59.7 9.46 7.0 found: 59.7 9.49 7.0 in an analogous manner when using 2.2t-aso-bis- (a-cyelopropyl3propionitrile) the 2,2'-azo-bis (a-cyclopropyl) propionic acid (6-hydroxy-hexyl) ester.

Example 4 150 ml of butanediol (1,4) in 75 ml of benzene are mixed with HC1 gas saturated until nothing more crystallizes out at OOC. Then 25 ml Benzene and 16.4 g of AIBN were added. The reaction mixture is at OOC with WC1 gas saturated and stirred at OOC overnight. After adding 50 ml of ice water, the The benzene phase is separated off and the aqueous phase is washed with 50 ml of benzene. To Washing neutral, drying and removal of the benzene leaves 20.5 g of azo-bis-isobutyric acid (4-hydroxybutyl) ester.

Analysis: G H N calc .: 55.4 8.66 8.1 found: 55.7 8.80 8.2 Example 5 A mixture. of 16.4 g of AIBN and 40 g (0.5 mol) of propanediol- (1.2) in 200 ml of benzene is saturated at 400 with HCl gas. The mixture is then stirred at OOC for 70 hours. After adding 100 g of ice and 100 ml of water, the benzene phase is separated off and the aqueous phase extracted with 50 ml of benzene. The benzene phases are mixed with NaCl and NaHCO 3 solution washed neutral and dried with MgSO 4. After distilling off of benzene at 4000 hours under reduced pressure, 27.7 g of a pale yellow remain Oil of azo-bis-isobutyric acid (2-hydroxypropyl) ester.

Example 6 16.4 g (0.1 mol) of AIBN and 100 g of polyethylene glycol 300 in 200 ml of benzene are saturated with HC1 gas at 5 ° C. The reaction mixture is over Stirred overnight at 000 and transferred to a separating funnel. The lower phase will dropped into 150 ml of water and 200 g of ice. A yellow colored benzene phase separates from about 100 ml, which is washed neutral. The aqueous phase is with 200, 100 and 100 ml of CKC1 extracted.

The extracts are washed neutral and dried, and the chloroform will be removed. The polyethylene glycol-300-diester of azo-bis-isobutyric acid is obtained as a weakly colored, water-soluble oil. The gel chromatographic analysis shows that the product no longer contains any starting material.

Yield: 47 g from the 011013 phase; 6'8 g from the benzene phase Analysis: C H N calc .: 52.8 8.54 3.5 found: 52.5 8.49 3.8 2,2'-azo-bis (α-cyclohexyl) propionitrile gives the 2.2t-azo-bis (a-cyclohexyl) propionic acid (polyethylene glycol) ester under analogous reaction conditions.

Example 7 16.4 g (0.1 mole) AIBN, 85 g (0.2 mole) polypropylene glycol 425 and 300 ml of benzene are saturated with HCl at 200. Then 24 h at o ° a stirred. Then the reaction mixture is poured into a separating funnel with 100 g of ice and 100 ml of water shaken. The pale yellow benzene phase is separated off and worked up as usual. After removing the benzene are in the oily substance Contains remains of AIBN crystals. These are separated and one obtains 33 g of the polypropylene glycol diester of azo-bis-isobutyric acid as a pale yellow oil.

The aqueous phase is extracted with 150, 50 and 50 ml of chloroform and the extracts are worked up as usual.

Yield 68.1 g of clear yellow oil.

Example 8 100 g (0.1 mol) of molten polyethylene oxide 1000 (polywax 1000, Hüls), which had been heated to 8000 for 5 hours in an oil pump vacuum to dry, and 150 ml of benzene are slowly increased from 35 to 5 ° C. while passing through HCl gas cooled so that no polywax crystallizes out. Then 8.2 g (0.05 mol) of AIBN and 25 ml of benzene are added and the reaction mixture is saturated with HCl at 50C. After stirring for 15 hours at 0 ° C., the homogeneous reaction solution is poured into a separating funnel treated with 100 g of ice. A clear benzene phase of about 75 separates ml from. After adding 200 ml of water, a Get emulsion. Phase separation is achieved by adding 250 ml of chloroform. The watery one Phase is extracted with 100 ml of chloroform. The organic extracts obtained are then worked up as usual. Gel chromatographic analysis shows that the reaction product, the polyethylene glycol 1000 diester of azo-bis-isobutyric acid, does not contain any starting material.

Yield: 87.9 g of waxy, water-soluble product.

Analysis: C H N calc .: 54.0 8.9 1.3 found: 54.2 8.99 1.46 Example 9 a) A mixture of 33 g of AIBN (recrystallized, dried over P4010), 200 ml fresh distilled glycol and 200 ml of dry benzene is mixed with dry HCl gas at 0 ° C saturated. The mixture is then stirred at 0 ° C. overnight.

The two-phase reaction mixture is filled with 20 g in a separating funnel Ice well shaken. The lower phase is washed with 100 ml of benzene. The combined benzene extracts are washed with saturated sodium chloride and bicarbonate solution washed neutral and dried with magnesium sulfate.

After removing the benzene, stay on the rotary evaporator at 3000 55.1 g of a pale yellow oil, which can be removed with methanol or petroleum ether let small amounts of a solid polymer precipitate. Azo-bis-isobutyric acid-β-hydroxyethyl ester is obtained as yellow oil.

b) A 1 liter autoclave containing a solution of 30 g of azo-bis-isobutyric acid-ß-hydroxyethyl ester in 250 ml of methanol, is flushed with N2 until the atmospheric oxygen is displaced is.

At OOC, ethylene is injected with 60 and the reaction is carried out at 850C in the course of 6 hours. The solid, white polymer is filtered off with suction after cooling and dried (109 g). It is recrystallized from toluene. It can be characterized by the following formula: where n 'means an average degree of polymerization of 28. Bullioscopy gives an Mn value of 1100.

c) 43 g of vinyl acetate and 5.8 g of azoisobutyric acid β-hydroxyethyl ester are dissolved in 100 ml of Toulol and quickly heated to 110 ° C. in a pressure bottle. After a reaction time of 5 hours, the toluene and unreacted vinyl acetate are removed on a rotary evaporator. 37.5 g of a viscous, pale yellow reaction product with Mh = 1757, which can be characterized by the following formula, are obtained: where n 'means an average degree of polymerization of 17.4.

Example 10 A mixture of 4.1 g (0.025 mole) AIBN, 100 g dry Polypropylene glycol 2000 and 330 ml of absolute benzene are saturated with HCl gas at 5 ° C and then stirred at 0 ° C. for 70 h.

The reaction mixture is then placed in a separatory funnel weighing 200 g Ice cream. and the lower phase is stirred into 200 ml of ice water. The upper Phase (benzene) is discarded.

The aqueous phase is extracted with 200, 100 and 100 ml of chloroform. The extracts are washed neutral with saturated sodium chloride and bicarbonate solution and dried. The Chloroorm is (last in an oil pump vacuum) on the rotary evaporator removed at 30 ° C.

Yield: 85.4 g of polypropylene glycol diester of azo-bisisobutyric acid.

Analysis: C H er .: 61.4 10.16 61.74 10.03 Example 11 50 g dry Polywax 3000 (polyethylene glycol) and 250 ml of benzene are mixed with HCl gas at 2500 saturated. Subsequently, with further introduction of HC1 gas, the cooling is carried out so slowly that ate no polywax crystallized out. When 50C is reached, 4.1 g of AIBN will be obtained and 25 ml of benzene are added and the mixture is at this temperature with HCl gas saturated. Then stirred overnight at OOC.

The main amount of benzene and HCl is then used on the rotary evaporator without external heating removed, the residue shaken vigorously with 100 g of ice and until neutralized with firm Bicarbonate added. With 400G, the rest of the Benzene and the water removed on a rotary evaporator and the residue is at 40 ° C extracted several times with benzene.

After removing the benzene, 137.5 g of the polyethylene glycol diester are obtained the azo-bis-iso-buttersellre with a melting point of 53 ° C.

Claims (16)

Claims ß Symmetrically substituted azo compounds with functional groups of the formula I. where Y is OH- or halogen, preferably C1, R- methyl R2 is lower alkyl or cycloalkyl or together with R1 is cycloalkyl, and A is an aliphatic hydrocarbon radical which can optionally be interrupted by oxygen atoms in an ether bond. 2. Azo compounds of the formula I according to claim 1, characterized in that that A is a straight or branched, aliphatic hydrocarbon radical with 2 - 20, preferably 2-6, carbon atoms. 3. Azo compounds of the formula I according to claim 1, characterized in that A is a radical of the formula where R is hydrogen or methyl and m is 1-149, preferably 1-75. 4. Azo-bis-isobutyric acid-ß-chloroethyl ester 5. Azo-bis-isobutyric acid-ß-hydroxyethyl ester 6. Azo-bis-isobutyric acid (2-hydroxypropyl) ester 7. Azo-bis-isobutyric acid (4-hydroxy-butyl) ester 8. Azo-bis-isobutyric acid (6-hydroxy-hexyl) ester 9. Azo-bis-isobutyric acid triethylene glycol ester 10. Polyethylene glycol azo-bis-isobutyric acid 11. Azo-bis-isobutyric acid polypropylene glycol ester 12, Process for the preparation of symmetrically substituted azo compounds with functional groups of the formula I. where Y is OH or halogen, preferably Cl, R1 is methyl, R2 is lower alkyl or cycloalkyl or together with R1 is cycloalkyl, and A is an aliphatic hydrocarbon radical which can optionally be interrupted by oxygen atoms in an ether bond, characterized in that symmetrical azonitrile compounds of the formula II where R1 is methyl R2 is lower alkyl or cycloalkyl or together with R1 is cycloalkyl, with difunctional compounds of the formula III HO - A - Y III where Y is OH or halogen, preferably Cl, and an aliphatic hydrocarbon radical which is optionally substituted by oxygen atoms in The ether bond can be broken in the presence of acid, preferably hydrogen chloride, under anhydrous conditions and the imidoester acid addition salts thus obtained are hydrolyzed. 13. The method according to claim 12, characterized in that the Implementation in an organic, hydroxyl-free solvent. 14. The method according to claims 12 and 13, characterized in that that to 1 mole of azonitrile compound of the formula II from 2 to 20 moles of the difunctional Compound of the formula III is used. 15. The method according to claims 12-14, characterized in that that as a difunctional compound of the formula III ß-chloroethanol, ethylene glycol, Propanediol, butanediol, hexanediol, di-, tri- or tetra-ethylene glycol, polyethylene glycol or polypropylene glycol is used. 16. Use of the azo compounds of the formula I as free radical donors Initiators in polymerization reactions.