DE2057225C3 - Process for the production of thermally stable polyquinazolines - Google Patents

Description

N = CR ₃ -C = N

Cl Cl

with dinitriles of the general formula N = CR ₊ -C = N

3. Iminochloridonitrile of the general formula

N = C-R ,,

/ γ ι

N = C-R ₅ -K) j Cl

It is known that the industry, particularly the electrical industry and the aerospace industry, more and requires more polymers that are stable at high temperature. In order to meet this demand, one already has a certain number of heterocyclic polymers produced under an inert atmosphere proven to be thermally stable. However, they are generally in corrosive or oxidizing atmospheres

Spheres much less stable. They are still ahead expensive mainly due to the price of the raw materials. The invention aims to overcome these disadvantages and to provide a process for the production of heterocyclic polymers that are not only used in

inert atmosphere, but also in an oxidizing atmosphere are stable.

The invention relates to a process for the production of thermally stable polyquinazolines, thereby ge " indicates that one is either

1. Diiminochioride of the general formula

with yourself or
4. Iminochloridonitrile of the general formula

N = CR ₃ -C = N

Cl
with yourself or

5. Polyiminochloride with repeating units of the general formula

40 R ₁ -C = N

Cl
with dinitriles of the general formula

N = CR ₄ -C = N
or

N = C - R ₁

Cl

with mononylrils of the general formula R ₇ - C = N

in which R _{1 is} an aromatic radical, R _{2 is} a direct bond or a - CH ₂ , - CO, - O, - SO ₂ - or - S radical, R _{3 is} an arylene radical, R _{4 is} an arylene or aralkylene radical , R _{5 is} a direct bond or an arylene, alkylene or aralkylene radical, R _{6 is} an aryl radical or lower-alkyl radical, R _{7 is} an aryl, alkyl or aralkyl radical and in which the phenyl or phenylene radical

O>

2. Diiminochioride of the general formula

<£> -N = CR ₃ -C = N ^ D>
Cl CI

with dinitriles of the general formula

50 N = C-R ₄ -C = N

or

3. Iminochloridonitrile of the general formula

N = C-R ,,

/ γ ι

N = C - R, - + Ο I Cl

6o + OJ

optionally one or more lower alkyl, with itself or
4. Iminochloridonitrile of the general formula

N = C- R., - C = N - ~ Co)>

with yourself or

5. Polyiminochloride with repeating units the general formula

with mononitriles of the general formula ic

R ₇ -C = N

in which R _{1 is} an aromatic radical, R is a direct bond or a - CH ₂ , - CO, - O, - SO, - or - S radical, R _{3 is} an arylene radical, R _{4 is} an arylene or aralkylene radical , R _{5 is} a direct bond or an arylene, alkylene or aralkylene radical, R _{6 is} an aryl radical or lower-alkyl radical, R _{7 is} an aryl, alkyl or aralkyl radical and in which the phenyl or phenylene radical

differ from the products obtained by the process according to the invention.

The inventive method uses the possibility of adding the nitrile functions to the Iminochloride functions, these additions of followed by a cyclization to form the quinazoline rings.

In process variants 1 and 2, the first compound carries two iminochloride functions and the second compound two nitrile residues. For this implementation, the basic reaction, which results in chain extension repeatedly, can be illustrated by the following equation, the Lewis acid being aluminum chloride is:

R, -C = N- <

N = C-R,

Cl

Cl

+ N = CR ₄ - Cs = N + AlCl ₃

optionally one or more lower alkyl, lower Contains alkoxy radicals or halogen atoms in one or more of the free positions of the ring, at temperatures from 60 to 180 "C in the presence of Lewis acids in the usual Friedel-Crafts reactions Reacts solvents.

In the general formula for the diiminochloride of process variant 1, the radicals R _{1 can be} identical or different.

From J. Polym. May be. Part C, No. 22, pp. 827 to 848 (1969) was already the production of polythene Compounds based on diaminodicarboxylic acids by acylation and reaction with Amines, known. However, this involves the production of polyquinazolones.

From the Japanese patent 68 11 239 referred to in CA 70, 4813 K (1969) it is known to produce polymeric products from aromatic diaminodicarboxylic acids and dicarboxylic acid diamides. The compounds obtainable thereafter are polyhydroxyquinazolines or polyquinazolones and thus have a different basic structure than the compounds obtainable according to the invention. Furthermore, reaction times of several days are required in the processes of the cited references, whereas a reaction time of about ¹ l ₁ hour is sufficient according to the process according to the invention. In addition, the products obtained by the process according to the invention do not have to be thermally aftertreated in order to improve their mechanical properties, whereas according to J. Polym. May be. a rapid thermal treatment of 380 ° C is carried out. Finally, it is also possible, by the method according to the invention, to obtain products which are distinguished by their low deformability.

From Chem. Ber. 89, No. 2, pp. 224-238 (1956) it is known to quinazolines prepare by reacting Iminochloriden with nitriles at 90 to 160 ⁰ C in the presence of an electrophilic metal chloride in a solvent such as nitrobenzene, o-dichlorobenzene or tetrachloroethane . These are monomeric reaction products that differ structurally and with regard to their mechanical properties

HN '

R ₄ -C = N

In process variant 1, the reaction product is a polyquinazoline which is characterized by the following general Formula can be represented:

R, v N-

j!

N
'Y

Mr,

R ₁ , R ₂ and R _{4 have} the meanings given and η denotes the number of units forming the polymer. In particular, R ₁ can be a phenyl group and R _{2 can be} a direct bond.

In process variant 2, the reaction product obtained is a polyquinazoline of the following general terms Formula:

(ID

wherein

R ₃ and R _{4 have} the meanings given. In particular, the radicals R ₃ and R _{4 can represent} phenylene groups.

In process variants 3 and 4, the compound used in each case in the reaction also carries an imino chloride function and a nitrile radical.

The polyquinazolines obtained according to these variants can be represented by the following formulas:

(III)

(IV)

wherein R ₃ , R ₅ . Around

have the meanings given.

According to variant 5, a polyimino chloride is used. whose repeating units are groupings

have, reacted with the nitrile of the formula R ₇ - C = N, in which R ₂ and R _{7 have} the meaning given.

The polymer obtained can be described by the following general formula:

(V)

in which R ₂ and R _{7 have} the meanings given. R ₇ can in particular represent a phenyl or methyl group.

The Lewis acid used can be any of those commonly used in Friedel-Crafts addition reactions Be kind. For example, aluminum chloride, antimony pentachloride, ferric chloride and Tin (IV) chloride is particularly well suited for these reactions.

Any solvent can be used which is suitable in Friedel-Crafts reactions and which allows the temperature range from 60 to 180 ° C., advantageously around 120 ^° C., to be used. Suitable solvents are nitrobenzene, ortho-dichlorobenzene and tetrachloroethane.

The polyquinazoline obtained can be removed from the reaction medium in any suitable manner from the Lewisic acid separated, especially by precipitation in ether and treatment with a base or by precipitation in an alcohol to which, if necessary: a base is added. or by separating the: Solvent and decomposition of the polyquinazoline catalyst complex by the action of what steam.

The starting poly iminochlorides can generally be obtained by reacting the corresponding amides with an acid chloride such as PCl ₅ and SOCl ₂ in the absence of a solvent or in the presence of an inert volatile solvent such as benzene or carbon tetrachloride, advantageously at a temperature between 80 and 120 ^° C. The imino chloride is obtained by separating off the solvent, the reaction by-products and the excess of the acid chloride, in particular by evaporation.

As starting diamides, N.N'-dibenzoylbenzidine, Isophthaldianilide or TerephthaJdianilid are used , it being possible to use isophthaldinitrile or terephthaldinitrile as dinitrile. As a starting compound for the Iminochloridnitril z. B. used the para-benzoylaminobenzonitrile will. One of the following polyamides can be used as the starting polyamide:

Poly (diphenyl isophthalamide), poly (diphenyl ether isophthalamide), Poly- (diphenylmethane-isophthalamide), poly- (diphenylsulfon-isophthalamide), Poly (phenyl ether terephthalamide), poly (diphenyl sulfone terephthalamide), Poly- (diphenyl-terephthalamide), poly- (diphenylmethane-terephthalamide),

wherein the compound having a nitrile moiety is benzonitrile or acetonitrile.

The imino chlorides used in process variants 1 to 5 can be obtained from the following amides will:

R ₁ -CO-NH

1 ₂ ^ €?> - NH-CO-R,

O> —NH -CO —R ₃ -CO —NH- \

NH-CO — R ₁ ,

N = C - R ₃ - CO - NH

Of-CO-NH-K OtR ₂ -H)) - NH-CO-

It is not necessary to isolate the iminochlorides, especially if the production of the iminochloride is already in progress is carried out in the presence of a solvent in which the Friedel-Crafts reaction is effected can be.

In addition, in the production of the iminochlorides, starting from the corresponding amides.

Lewis acid, which is responsible for the preparation and the solution of the iminochlorides, which after the addition of the Compounds with nitrile residues to the desired Polyquinazolines make it easier.

The conversion of amide groups to iminochloride groups and the reaction of compounds which carry the iminochloride groups with compounds which have nitrile radicals can be in one and the same Stage.

The synthesis of polyquinazoline can be effected by using a solution of a mixture the compounds with amide residues, compounds with nitrile residues. Acid chloride and Lewis acid in stoichiometric Contains proportions in the cyclization solvent, heated.

It should be noted, however, that in the case where a polyamide is used, the polymer structure the polyquinazoline is caused by the polyiminochloride, d. H. before the cyclization occurs.

You can use an excess of mononitrile, this compound at the same time the role of Reactant and takes over the role of the reaction solvent.

The compounds prepared according to the process of the invention lie after drying in the form of powders, the hue of which is most often between yellow and brown. Depending on the type of These powders are complete infusible or have softening points at temperatures between 250 and 300 ° C. These powders are partially or completely soluble in concentrated sulfuric acid, however certain compounds are also in chloroform. Nitrobenzene. Dimethylformamide and formic acid and amide-like solvents such as N-methylpyrrolidone soluble. The infrared spectrometric investigations and the isobaric distillations show the Presence of quinazoline moieties and have molecular weights of at least 2000 and higher up. especially if the starting product is already formed by a polyamide. When the received Powders are soluble, one can measure the viscosities and have characteristic film-forming properties of masses with a higher molecular weight.

As can be seen from the following examples, shows the thermogravimetric analysis of the products manufactured by the method according to the invention very good stability in an oxidizing atmosphere as well as in an inert atmosphere.

example 1

Condensation of N.N'-dibenzoylbenzidine
with terephthalonitrile

3.9 g (0.01 mol) Ν, Ν'-dibenzoylbenzidine and 4.4 g (0.021 mol) phosphorus pentachloride in 40 ecm nitrobenzene are stirred under an inert atmosphere at a temperature of 120 ° C. Complete solution is achieved quickly (approx. * ₄ hours). After heating for one hour, 1.3 g (0.01 mol) of terephthalodinitrile are added, which dissolves in the yellow-orange reaction mixture, and then a further 2.9 g of powdered aluminum chloride are added. The addition of this latter material at 120 "C causes a rapid discoloration of the solution to a brown-black color, which deepens in the course of further heating for 3 hours, the final temperature reaching 200 ° C. ^

The resulting cooled solution is freed from a small amount of insoluble product by d-.srch filtration. Starting from the filtrate, about 6 g of a brown-yellowish powder are precipitated with ether. After drying and treating by stirring with aqueous 20% IGCR sodium hydroxide solution for 2 hours, after acid washing and drying in vacuo at 100 ^'1 C, however, are obtained 3.4 g of a brown powder, which is infusible at 360 "C. In the cold is soluble in nitrobenzene, chloroform and in concentrated sulfuric acid.

Example 2

Condensation of Dibcnzoylbenzidin
with isophthalonitrile

One proceeds in the same way as indicated in Example 1. by making the tetraphthalonitrile through Isophthalonitrile replaced taking into account the molar ratios.

After the reaction, the reaction medium does not contain any insoluble products. After the precipitation with Ether one receives 6.3 g of a light chestnut-colored powder, which after treatment with sodium hydroxide solution, washing and drying in vacuo (0.01 mm Hg) at 130 "C. 4.6 g of a yellow-orange powder results, which is soluble in chloroform and softens at 330'C. The molecular weight, determined by isobaric distillation, is 2000.

Example 3

Condensation of isophthalodianilide
with isophthalodinilril

3.15 g isophthalodianilide (0.01 mol) and 4.4 g PCl ₅ (0.021 mol) in 25 ecm nitrobenzene are stirred at "120" C under an inert atmosphere for one hour (complete solution). 1.3 g (0.01 mol) of isophthalonitrile and 2.65 g of pulverized aluminum chloride are then added. At 120 ^° C., the solution immediately becomes very dark brown. After heating. 1 hour at 120 ⁰ C, 1 hour at 140 ⁰ C. for 1 hour at 160 ⁰ C. for 1 hour at 180 ° C and 1 hour at 200 ° C, the cooled solution contains no insoluble products by precipitation with ether to obtain 5.8 g of of a brown powder and this amount decreases to 4.1 g after treatment with sodium hydroxide

The product obtained softens, starting be; 300 ⁰ C, and is soluble in concentrated sulfuric acid and formic acid, only partially soluble in chloro form, nitrobenzene, dimethylformamide, dimethylacetamide and N-methylpyrrolidone. Its ash content still indicates an aluminum content of 1.25%

The following table shows the relative weight losses as a percentage, which the results f the thermogravimetric analysis carried out in nitrogen and in air (Tempe rate of rise: 5 ° C / minute), which are all characteristic of the thermal behavior poly quinazolines made in accordance with the present invention.

Atmo- temperature (C)

sphere 400 500 MJO 700 800 900 1000

N, η 2% 7% .17.5% 2!% 22.5% 23% air 1% 2% 5% 16% 21.5% 22.5% 32%

609 626/145

In the following three examples, the same Case concern are the process conditions, the reaction products, except for diamide and dinitrile, as well the molar ratios are the same as given in Example 3.

Example 4

Condensation of isophthalodianilide
with terephthalodinilril

The procedure described in Example 3 is followed. by getting isophthalonitrile in the same molar ratios replaced by tercphthalodinitrile. The end product is a gray mauve powder that is present in all Solvents, with the exception of sulfuric acid, is insoluble.

Example 5

Condensation of terephthalodianilide
with isophthalonitrile

The same conditions as in Example 3 are used, the reactants in the same molar ratios were used. The end product is a brownish yellow powder that softens around 350 ° C and is completely soluble in sulfuric acid and formic acid.

Example 6

Condensation of terephthalodianilide
with terephthalonitrile

1.6 g of the finely divided polyamide and 2.5 g of phosphorus pentachloride in 25 ecm benzonitrile are stirred for 15 minutes at 110 ° C. To the obtained A yellow-greenish suspension is added at this temperature and 1.7 g of aluminum chloride all at once. The The reaction medium immediately turns to a gel with a red-orange color. that little by little liquefies and forms a highly viscous solution. The reaction is carried out at 110 for half an hour

ίο continued up to 120 ⁰ C. After cooling, the product is precipitated with methanol; the yellow powder obtained is treated several times with methanol and then with ether and then dried at 100 ° C. in vacuo. Finally obtained 1.8 g of a white-beige powder that looks dark brown in bulk and has a softening point in the range of 300 C ^c. This compound is soluble in tetrachloroethane, nitrobenzene, N-methylpyrrolidone and pyridine. Inherent viscosity: i _n " _h = 0.3 to 0.4 dl / g

(determined at 30 ¹ C for 0.5% solutions in N-methylpyrrolidone). Films could be produced from solutions in this latter solvent.

The elementary analysis of this product gave the

following results:

C = 81.06%. N = 11.0%, H = 3.61%.

where the formula calculated for this elemental composition was the following:

The same conditions as in Example 3 are used, the reactants being used in the same molar ratios. The end product is a brown-yellowish product which is ^{infusible around 360 °} C. and is only completely soluble in sulfuric acid.

40

Example 7
Condensation of para-benzoylaminobenzonitrile

N-

-O

This product is nitrile and amide at the same time and is produced by the action of copper (I) cyanide on the Obtained N-benzoyl derivative of para-bromoaniline.

2.2 g (0.01 mol) desNitrilamidesund2,4g (0.011 mol) of PCl ₅ are stirred in 25 cc of ortho-dichlorobenzene for 30 minutes at 120 ⁰ C. The yellow solution obtained is mixed with 1.4 g of aluminum chloride, which dissolves in it. After one hour at 140 ^° C., a deposit forms on the walls of the vessel. Heating is continued for 2 hours, gradually increasing the temperature to 170 ° C. After treatment with ether and then with sodium hydroxide, as already stated, 2.6 g of a light brown powder are obtained which softens at about 360 ° C., but is insoluble in all solvents.

Example 8

The cyclizing agent of the Friedel-Crafts type is replaced by an excess of mononitrile.

The polyamide is a poly-idiphenyl ether isophthalamide which was produced from 4,4-diamino-diphenyl ether and isophthaloyl chloride.

C = 81.6. N = 11.2. H = 4.0%.

As in the previous example, the thermogravimetric Analysis shows a significant "improvement in the thermal stability of the polyquinazoline ir Nitrogen and in air versus polyamide.

Example 9

Production of polyquinazoline,
which is derived from poly (diphenylether-isophthalamide) modified with acetonitrile

1.6 g polyamide and 2.5 g phosphorus pentachloride ii 50 ecm of nitrobenzene be for 15 minutes

Stirred at 120 ° C. 1.75 g of tin dichloride are added to the solution obtained. The color changes η a dark brown. Immediately add 5 ecm of aceto nitrile. The reaction is continued for 30 minutes while keeping the temperature of the reaction

mixture then reaches 125 ° C. After the precipitation in methanol, hem washing with rä & sxinmhydroxyi and the drying gives 1.9 g of a yellow-green borrowed fibrous product which heats up to 275.degree

The elemental analysis gives the following result: C = 74.86%, N = 14.10%, H = 4.32%.

where the calculated composition of the repeating unit is the following:

cn.,

C - 76.6. N = 14.89. H = 4.26 ".,

A. ■ r ^N ) V -O- \)
j CH

Inherent viscosity:; /, ",, = 0.41 dl / g (concentration = 0.5% in N-methylpyrrolidone).

Example 10

Polyquinpzoline, which is different from poly- (diphenylmethanisophthalamide) and benzonitrile

1.6 g of the polyamide and 2.3 g of PCl ₅ in 30 ecm nitrobenzene are stirred at 120 ° C. Complete solution is achieved after 35 minutes. 5 ecm benzonitrile and then 1.5 g aluminum chloride are added and the reaction is allowed to take place proceed further for 30 minutes at 120 ⁰ C. Starting from the brown solution obtained is isolated by precipitation in methanol, 2.2 g of a yellow powder which is soluble in Nilrobenzol, N-methylpyrrolidone, and sulfuric acid, and does not melt at 360 ° C.

Inherent viscosity = 0.323 dl / g (0.5% in N-methylpyrrolidone).

Analysis:

Found ... C 85.10,
calculated ... C 84.3,

N 10.33, H 4.33%:
N 11.23. H 4.42%.

Example 11

Inherent viscosity = 0.57 dl / g (0.5% in N-methylpyrrolidone).

Analysis:

Found ... C 81.50, N 10.66, H 4.03%;
calculated ... C 81.6, N 11.2, H 4.0%.

Example 13

Polyquinazoline. derived from poly (biphonic terephthalamide) and benzonitrile

One works under the same process conditions as in Example 12. The isolated product is only soluble in concentrated sulfuric acid and softens around 360 "C.

Example 14

Polyquinazoline, derived from poly- (diphenylmethane-tercphthalamide) and benzonitrile

The same process conditions as indicated in Example 12 are used. The product, which is only soluble in concentrated sulfuric acid. softens above 360 ° C.

25th

Example 15

Po'ychinazoline. derived from poly- (diphenylsulfonecrephthalamide) and benzonitrile

One works under the same conditions as in Example 14. The product, which is only in concentrated Sulfuric acid is soluble. softens by 360 C. It can be seen from the preceding examples that no polyimino chloride intermediates were isolated. However, as example 16 shows, you can according to the two stages: 1. Formation of the polyiminochloride. starting from polyamide, and 2nd conversion of the polyiminochloride.

40

Polyquinazoline, derived from poly- (diphcnylsulfonisophthalamid) and benzonitrile

The process conditions are the same as in Example 10. Starting from 1.9 g of polyamide, 1.95 g of a brown, fibrous product is obtained which is soluble in nitrobenzene, N-methylpyrrolidone and sulfuric acid and melts around 270.degree.

Example 12

45

Polyquinazoline, derived from poly (diphenyl ether terephthalamide) and benzonitrile

1.6 g of the polyamide and 2.3 g of PCl ₅ are stirred in 25 ecm of nitrobenzene at 120.degree. In this case, the polyimino chloride remains insoluble in the form of an intensely yellow powder. After 15 minutes are added 5 ml of nitrobenzene and 1.5 g of aluminum chloride. After heating to 120 ° C. for 30 minutes, a very viscous brown solution is obtained, from which 2.2 g of a yellow fibrous product are obtained by precipitation in methanol. The product is in concentrated sulfuric acid, as well as in N-methylpyrrolidone and in nitrobenzene. Soluble in the heat and softens around 380 ° C.

Example 16

The starting products are the same as in example 8. * "

1st stage

Production of the polyiminochloride

1.6 g of poly (diphenyl ether isophthalamide) and 2.2 g of phosphorus tachloride in 25 ecm of nitrobenzene are stirred at 120.degree. Complete dissolution is achieved in 15 minutes. The rather viscous yellow solution that is cooled to about 6O ⁰ C (below this temperature results in a cloudiness and then a precipitate) is poured into anhydrous ether. The fibrous, light yellow precipitate is dried at 80 ° C. in vacuo.

The elemental composition of this product is as follows:

C = 64.90%, N = 7.48%, H = 3.01%,

corresponding to the formula for the repeating unit

r ei

Cl

-C = N-: ο> o- < ο Vn = C-C ο

, «Lit the following calculated analytical series: C = 65.40%, N = 7.64%, H = 3.28%.

2nd stage

Conversion of the polyiminochloride
to polyquinazoline

0.6 g of this polyimino chloride are stirred in 25 ecm of benzonitrile with 0.55 g of aluminum chloride at 130 ° C. After one hour, the brown solution obtained is precipitated after cooling with the aid of methanol. After washing and drying, 5, 55 g of a light yellow powder, the properties of which are essentially the same as those of the product of Example 8. A polyquinazoline can also be prepared in an analogous manner, starting from poly (biphenylisophthalamide) which is converted into the corresponding iminochloride _{with the aid of PCl 5} The poly (biphenylisophthalamide) can be obtained by reacting benzidine and isophthaloyl chloride.

From the preceding examples it can be seen that the obtained by the process according to the invention Polymers have a considerable thermal stability, which is their system of conjugated Can attribute double bonds.

The method according to the invention, applied to aromatic polyamides, is of particular interest as it converts the same into easy-to-use ones Products. The aromatic polyamides can easily be obtained from cheap starting materials are obtained, but are themselves very difficult to handle. They often decompose before melt and are sparingly soluble, so that they can only be deformed under difficult conditions.

The polyquinazolines obtainable from them, on the other hand, do not decompose before melting and can be easily deformed.

The according to the inventive method

i_s hold polyquinazolines, according to which procedure they are also manufactured in numerous fields of application, especially in the Electrical and aerospace industries. can be used. They are used as binders for composite materials, as adhesive varnishes, as highly heat-stressed fittings and as Coverings and protective skins that can withstand temperature and radiation.

Claims (2)

Claim: Process for the production of thermally stable polyquinazolines, characterized in that either 1. Diiminochioride the general formula lower alkoxy radicals or halogen atoms at one or more of the free positions of the containing ring, wherein Tempe ^r aturen 60-18 (TC in the presence of Lewis acids in in Friedel-Crafts reactions, conventional solvents are reacted. R ₁ -C = N - \ ^ G ^ R, - ^ O _/ > -N = C-R ₁ Cl Cl with dinitriles of the general formula N = CR ₄ -C = N or
2. Diiminochioride of the general formula O> - N = CR ₁ -C = N ^ CO IO