SU759547A1 - Method of preparing polyamidobenzoxazoles - Google Patents

Description

The invention relates to the field of high-molecular compounds, namely to the synthesis of fire, heat and heat resistant polymers that can be used in various fields of technology.

A method of obtaining polyamidebenebxaaols, based on the interaction of diphenyl ethers of aromatic dicarboxylic acids, 10 containing amide fragments, with bis (o-aminophenols) at a temperature of 9OO'S [1].

However, with this method it is necessary to use as a nucleophilic monomer relatively difficult to access and easily oxidized bis (o-aminophenols), which complicates the technological design of the process at high temperatures. 20

There is also known a method for producing polyamide boene oxazoles, based on the interaction of aromatic diamines containing benzoxaol cycles with aromatic 25 dicarboxylic acid dichlorohydrides under conditions of low-temperature polycondensation [2].

The lack of synthesis of polyamidobeneoxazoles on the specified method 39

2

it also consists in the use of o-aminophenols directly for synthesis with beneoxazole cycles, which are difficult to identify 5 and, accordingly, inaccessible monomers.

There is also known a method of producing polyamide-boeoxazoles, which is based on the interaction of diaminophenols containing one of the amino groups in the ό-position to the hydroxyl group, with dichloroane hydrides of aromatic dicarboxylic acids, followed by solid-phase cyclodegeneration of the obtained poly (o-hydroxy) amides to polyamideoene oxazoles, and in the subdivision. ⁱⁿ C £ s].

This method of synthesis, polyamidobeneoxazoles has the following disadvantages:

the need to use as monomers relatively difficult and easily oxidized diaminophenols,

carrying out the process of polycyclode hydration of poly (o-hydroxy) amides under severe conditions (not lower than 300 * C), which not only complicates the technological design of the process * but also causes side processes such as "crosslinking", destruction, etc.

5954 '

The purpose of the invention is the development of a method of obtaining linear polyamidobeneoxazoles based on available monomers with solubility in organic solvents.

This goal is achieved by the fact that polyamide benzoxaols are obtained by successive polycondensation reactions of dichlorides.

aromatic dicarboxylic acids and aromatic oxyamine formula

reduction and polycyclodehydration of the (o-nitro) ether amides formed in the first stage.

The schematic diagram of the reaction can be represented as follows:

+ HRP-C-Ya-C-X Ҥ -glnh

-np

ί

-5O, -; - С (СГ,);

X »G, Zg or C1

The application of the proposed method of producing polyamide benzoxazoles provides in comparison with the known the following advantages:

the use of aromatic o-nitrooxylamines instead of diaminophenols, which are intermediate compounds in the synthesis of the first, and therefore cheaper and more accessible; in addition, they are resistant to oxidation compared to diaminophenols;

carrying out the processes of reduction and cyclization of poly (o-nitro) ether amides under mild conditions in organic solvents without the occurrence of secondary gelling processes ί

high solubility polyamide-. bio-oxazoles in organic solvents Allows easy processing of these polymers from their solutions into various products.

The process of reducing poly (o-nitro) ether amides to poly (o-amino) ether amides and polycyclodehydration of the latter is preferably carried out in the form of combined processes using metals or their salts (for example,

Re or 5 and C1 ₂ ) with hydrogen chloride or other acids (for example,

HCOOH, CH _H COOH, SG, COOH, or (COOH), which are simultaneously catalysts for the formation of the beneoxazole cycle in the temperature range 150160 * 6 in the environment of various organic solvents. At the same time, linear polyamide benzoxaols are formed, precipitated by solubility in dimethylformamide, dimethylacetamide, hexa-, methylphosphoramide, N-methyl-2-pyrrolidone and strong acid solvents with the formation of highly concentrated blood solutions (at least 25% by weight of polymer); the reduced viscosity of the synthesized polyamide benzoxaols in organic solvents is at least equal to

50 0.50 dl / g.

According to dynamic thermograms. In polymetric analysis, polyamidobene-aseaols are not destructed by

55 air to 400®С. On their basis, carbon-fiber plastics with a static bending strength of 3200-3500 kg / cm ² at 25 ° C and 2500-2700 kg / cm ² · at 265 ° C are obtained, depending on the structure of the original poly 40.

Synthesized intermediate polymer products and polyamidobenzo'xazoles are characterized by the reduced viscosity of their solutions, UV and IR spectra, as shown in elemental data.

liaa, as well as the properties of carbon-based plastics obtained on their basis.

In a three-neck flask with a capacity of 200 ml, equipped with a stirrer, inlet for an inert gas, load 10

1.541 g (0.01 mol) of 2-nntro-4-aminophenol, 20 ml of M-methdl-2-pyrrolidone, 2.6 ml (0.02 mol) of triethylamine and with stirring in a stream of inert gas at 20 ° C to the reaction solution , add 2.040 g (0.01 mol) of eophthalic acid dichlorohydride, while the reaction temperature * spontaneously rises to 35 ° C. The reaction solution was stirred at 25 ° C for 1 h, obtaining a light brown, uniform solution of poly (o-nitro) ether amides. A small portion of the polymer is poured into distilled water, producing light orange poly (o-nitro) ether amide fibers. The reduced viscosity of the polymer in m-creole at 25 ° C is 0.43 dl / g.

In the remaining reaction solution, 5 g of reduced iron will be prevented and hydrogen chloride will begin to flow. Due to the heat of the exothermic reaction, and then due to external heating, the temperature of the mixture is raised to 150 ° C and maintained at this level for 3 hours; at the same time, the solution gradually turns a light green color. Then the reaction solution is cooled to 80 ° C, passed through a glass filter and poured into water. The precipitated bright precipitate of polyamidobenzoxazole is filtered off, dried with water until neutral, extracted with acetone and dried in vacuum at 80 ° C to constant weight.

• The polymer yield is 96% of the theoretical, the reduced viscosity of a 0.5% polymer solution in dimethylformamide at 25 ° С is 0.52 dl / g.

Polyamide-based polyamide-boleoxazoles are prepared as follows. A 25% polymer solution in dimethylformamide is impregnated with carbon fabric at 60 ° C. The impregnated fabric is kept in air at a temperature of 100 ° C and in vacuum, first at 120 ° C for 1 hour and then at 200 ° C for 2.5 hours and at 275 ° C for 0.5 hours. Dried fabric cut into sheets, which are collected in a bag and pressed at a temperature of 350 ^ 0 and a pressure of 70 kg / cm.

The tensile strength of carbon fiber bending is 3200 kg / cm ² at 125 ° C. 2400. Kg / cm * at 265 ° C and

20

25

thirty

35

40

45

50

55

60

2300 kg / cm ^and after thermal aging in air for 100 hours at 265 ° C.

PRI me R 2.

Y l

Synthesis of the polymer is carried out as described in Example 1, with the difference that instead of 0.01 mol of isophthalic acid dichlorohydride, 0.01 mol of chlorofluoride n hydride 4,4-di to arboxydiphenyl oxide is used.

The yield of polyamide benzoxazole is quantitative; reduced viscosity 0,61 DL / g; The tensile strength of the carbon based on it when bending is 3250 kg / cm ² at 25 ° C and 2200 kg / cm 'dri at 265 ° C.

Example 3

Synthesis of the polymer is carried out as described in Example 1, with the difference that instead of 0.01 mol of isophthalic acid dichloride, 0.01 mol of 4,4-dicarboxydiphenylsulfone dichloride is used.

Polymer yield quantitative; reduced viscosity 0.54 dl / g.

Example 4. Synthesis of the polymer is carried out as in example 1, with the difference that the polycondensation reaction is carried out in 20 ml of sulfolane; The subsequent stages of the conversion of poly (o-nitro) ether amide — the reduction and cyclization are also carried out directly in the reaction solution of the poly (o-nitro) ether amide.

Polymer yield quantitative; reduced viscosity 0,52 DL / g.

PRI me R 5.

The synthesis of the polymer is carried out as described in example 1, with the difference that instead of 0.01 mol of 2-nitro-4-aminophenol, 0.01 mol of 2-nitro-2-aminonaphthol is used.

The output of polyamide benzoxazole quantitative / reduced viscosity of 0.51 DL / g

Example b. Synthesis of the polymer is carried out according to Example 1, with the difference that dimethylacetamnd is used as a solvent, and instead of hydrogen chloride at war 65

759547

θ

',' / 7 / - formation and cyclization - oxalic acid.

The yield of polyamide benzoxazole is quantitative, the reduced viscosity is 0.58 dl / g.

Claims (1)

Claim A method of producing polyamide benzoxazoles by the polycondensation of o-substituted aromatic hydroxyamine of aromatic dicarboxylic acid dichlorohydride followed by cyclodehydration of the intermediate obtained by heating, characterized in that o-substituted hydroxyamine use a compound of the formula and the poly (nitro) ether amide formed in the course of condensation, prior to its licyclodehydration, undergoes a double formation, '