METHOD FOR PRODUCING A POLY(ANTHRANILAMIDE), POLY(ANTHRANILAMIDE) AND USE THEREOF

Abstract

The invention relates to a method for producing a poly(anthranilamide) via the polymerisation of isatoic anhydride, preferably in the presence of a solvent, on a starter at a reaction temperature in the region of 110° C. to 300° C., wherein the starter comprises an aliphatic mono- or diamine with 5 to 13 carbon atoms, an araliphatic mono- or diamine with 7 to 15 carbon atoms, an aromatic diamine with 6 to 13 carbon atoms, a carboxylic acid amide of formula Ar—(C═O)NHR, where Ar represents an aromatic group substituted with an amine NH— or NH2 group and R represents an aromatic or aliphatic group, or a mixture of the above-mentioned starters, and wherein the solvent, if used, comprises an organic solvent, which is in liquid form at the reaction temperature, an ionic liquid or a mixture of these solvents, obtaining a poly(anthranilamide) based on the starter. The invention also relates to the poly(anthranilamide) obtained with the method according to the invention and to the use thereof in the production of fibres or composite materials.

Claims

1. A process for preparing a poly(anthranilamide), comprising (A) providing isatoic anhydride; (B) polymerizing the isatoic anhydride onto a starter at a reaction temperature in the range from 110° C. to 300° C., wherein the starter comprises: an aliphatic mono- or diamine having 5 to 13 carbon atoms, an araliphatic mono- or diamine having 7 to 15 carbon atoms, an aromatic diamine having 6 to 13 carbon atoms, a carboxamide of the formula Ar—(C═O)NHR in which Ar denotes an aromatic radical substituted by an aminic NH or NH.sub.2 group and R denotes an aromatic or aliphatic radical, or a mixture of the aforementioned starters, to obtain a poly(anthranilamide) based on the starter.

2. The process as claimed in claim 1, in which the reaction temperature is in the range from 120° C. to 300° C.

3. The process as claimed in claim 1, in which the aliphatic primary or secondary mono- or diamine having 5 to 13 carbon atoms comprises neopentylamine, hexamethylenediamine, methylenedicyclohexyldiamine, pentamethylenediamine, or a mixture thereof and/or in which the araliphatic mono- or diamine having 7 to 15 carbon atoms comprises xylylenediamine, and/or in which the aromatic diamine having 6 to 13 carbon atoms comprises methylenediphenylenediamine, naphthylenediamine and/or tolylenediamine, and/or in which the carboxamide of the formula Ar—(C═O)NHR comprises N-neopentylanthranilamide.

4. The process as claimed in claim 1, in which the polymerizing is conducted in the absence of a solvent, wherein step (B) is followed by a process comprising: (C)(i) dissolving the poly(anthranilamide) in a mineral acid to obtain a mineral acid solution of the poly(anthranilamide); and (D)(i) isolating the poly(anthranilamide) dissolved in the mineral acid from the mineral acid solution, comprising a step of precipitating in water.

5. The process as claimed in claim 1, in which the polymerizing of the isatoic anhydride is conducted in the presence of a solvent, wherein the solvent comprises an organic solvent which is in liquid form at the reaction temperature, or comprises a mixture of such an organic solvent and an ionic liquid, and, in step (B), the poly(anthranilamide) based on the starter is obtained such that it is suspended in the solvent, wherein step (B) is followed by a process comprising: (C)(ii) dissolving the poly(anthranilamide) suspended in the solvent in a mineral acid and separating off the solvent to obtain a mineral acid solution of the poly(anthranilamide); and (D)(ii) isolating the poly(anthranilamide) dissolved in the mineral acid from the mineral acid solution, comprising a step of precipitating in water.

6. The process as claimed in claim 1, in which the polymerizing of the isatoic anhydride is conducted in the presence of a solvent, wherein the solvent comprises an ionic liquid or a mixture of an ionic liquid and an organic solvent which is in liquid form at the reaction temperature, and, in step (B), the poly(anthranilamide) based on the starter is obtained such that it is dissolved in the solvent, wherein step (B) is followed by a process comprising: (D)(iii)isolating the poly(anthranilamide) dissolved in the solvent from the solution in the solvent, comprising a step of precipitating in water.

7. The process as claimed in claim 5, in which the organic solvent comprises diphenyl ether, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide, or a mixture thereof, and/or in which the ionic liquid comprises 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium butyrate, 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium methylsulfonate, dialkylimidazolium phosphate, or a mixture thereof.

8. The process as claimed in claim 1, in which a molar ratio of isatoic anhydride to starter chosen in step (B) is in the range from 20 to 2500.

9. The process as claimed in claim 1, in which the providing of isatoic anhydride in step (A) comprises a chemical conversion of anthranilic acid.

10. The process as claimed in claim 9, in which the anthranilic acid is obtained by fermenting a raw material comprising: a fermentable carbon-containing compound, and a nitrogen-containing compound.

11. A poly(anthranilamide) of the formula
{H—[HN-(ortho-C.sub.6H.sub.4)—(C═O)].sub.m}x-A-[(O═C)(ortho-C.sub.6H.sub.4)—NH].sub.n—H in which m and n denote the number of repeat units, x is 0 or 1, A derives from a starter molecule comprising aminic NH or NH.sub.2 groups by removal of a hydrogen atom from all aminic NH and NH.sub.2 groups, wherein the starter molecule comprises: an aliphatic mono- or diamine having 5 to 13 carbon atoms, an araliphatic mono- or diamine having 7 to 15 carbon atoms, an aromatic diamine having 6 to 13 carbon atoms, a carboxamide of the formula Ar—(C═O)NHR in which Ar denotes an aromatic radical substituted by an aminic NH or NH.sub.2 group and R denotes an aromatic or aliphatic radical, or a mixture of the aforementioned starters.

12. The poly(anthranilamide) as claimed in claim 11, in which the aliphatic primary or secondary mono- or diamine having 5 to 13 carbon atoms comprises neopentylamine, hexamethylenediamine, methylenedicyclohexyldiamine, pentamethylenediamine, or a mixture thereof, and/or in which the araliphatic mono- or diamine having 7 to 15 carbon atoms comprises xylylenediamine, and/or in which the aromatic diamine having 6 to 13 carbon atoms comprises methylenediphenylenediamine, naphthylenediamine, tolylenediamine, or a mixture thereof, and/or in which the carboxamide of the formula Ar—(C═O)NHR comprises N-neopentylanthranilamide.

13. The poly(anthranilamide) as claimed in claim 11, in which m+n is in the range from 20 to 2500.

14. A fiber or composite comprising the poly(anthranilamide) as claimed in claim 11 and another material comprising a metal, a mineral material or a polymer other than poly(anthranilamide).

15. (canceled)

16. The process as claimed in claim 8, in which a molar ratio of isatoic anhydride to starter chosen in step (B) is in the range from 70 to 2000.

17. The process as claimed in claim 6, in which the organic solvent comprises diphenyl ether, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphoramide, or a mixture thereof, and/or in which the ionic liquid comprises 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium butyrate, 1-butyl-3-methylimidazolium nitrate, 1-butyl-3-methylimidazolium methylsulfonate, a dialkylimidazolium phosphate, or a mixture thereof.

18. The process as claimed in claim 10, in which: the fermentable carbon-containing compound comprises starch hydrolyzate, sugarcane juice, sugarbeet juice, a hydrolyzate of a lignocellulose-containing raw material, or a mixture thereof, and the nitrogen-containing compound comprises gaseous ammonia, aqueous ammonia, an ammonium salt, urea, or a mixture thereof.

19. The poly(anthranilamide) as claimed in claim 12, in which m+n is in the range from 20 to 2500.

20. The poly(anthranilamide) as claimed in claim 13, in which m+n is in the range from 70 to 2000.

21. The poly(anthranilamide) as claimed in claim 19, in which m+n is in the range from 70 to 2000.

Description

EXAMPLES

Analysis

[0102] The number-average molar mass (M.sub.n) of the resulting poly(anthranilamide) was determined by means of .sup.1H NMR spectroscopy (from Bruker, AV III HD 600, 600 MHz; pulse sequence zg30, delay time d1: 10 s, 64 scans). Each sample was dissolved in deuterated sulfuric acid. The relevant resonances in the .sup.1H NMR spectrum (based on TMS=0 ppm) are as follows:

[0103] The signals at 8.5-7.1 ppm are used for the aromatic protons of anthranilamide (corresponding to an integral of 4 protons). The resonances of the protons of the neopentylamine starter have a shift of 3.6-3.4 ppm (methylene group, corresponding to an integral of 2 protons) and 1.1-0.9 ppm (neopentyl group, corresponding to a integral of 9 protons).

[0104] The molar mass M.sub.n of the polymer is calculated according to formula (I) as follows, using the following abbreviations: [0105] F(A)=area of the resonance at 8.5-7.1 ppm of the aromatic protons (4 protons); [0106] F(M)=area of the resonance at 3.6-3.4 ppm of the methylene group of the starter (2 protons); [0107] F(N)=area of the resonance at 1.1-0.9 ppm of the neopentyl group of the starter (corresponding to 9 protons).

[0108] The following formula (I) was used to calculate the number m+n of repeat units from (O═C)(ortho-C.sub.6H.sub.4)—NH in the polymer (in the specific case, m=0, and therefore m+n=n):

[00001]$\begin{array}{cc}n=\frac{F\left(A\right)}{F\left(N\right)}.Math.\frac{9}{4}& \left(I\right)\end{array}$

[0109] The number n was used to calculate the molar mass M.sub.n of the polymer by the following formula (II):

M.sub.n=86.16 g/mol+n.Math.120.14 g/mol+1 g/mol  (II)

Example 1: Preparation of Poly(Anthranilamide) by Ring-Openinq Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in Diphenyl Ether as Solvent

[0110] Isatoic anhydride and diphenyl ether were sourced from Sigma-Aldrich, and neopentylamine from ABCR (step (A)).

[0111] A 500 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 98 g of isatoic anhydride and 171 g of diphenyl ether were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.26 g of neopentylamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A suspension was obtained.

[0112] The molar mass M.sub.n was determined in accordance with formula (II) by means of .sup.1H NMR in D.sub.2SO.sub.4.

[0113] 20 g of the poly(anthranilamide) suspension was dissolved in 20 mL of concentrated sulfuric acid. The precipitated solid (=diphenyl ether solvent) was removed by filtration (step (C)).

[0114] The filtered sulfuric acid solution was added to 300 mL of water (step (D)(ii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

Example 2: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in Diphenyl Ether as Solvent

[0115] The procedure was as in example 1, apart from the following differences:

[0116] 90 g isatoic anhydride, 130 g of diphenyl ether and 0.80 g of neopentylamine were used.

Example 3: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in Diphenyl Ether as Solvent

[0117] The procedure was as in example 1, apart from the following differences:

[0118] 100 g isatoic anhydride, 390 g of diphenyl ether and 0.060 g of neopentylamine were used.

[0119] The table below compares the analytical results.

TABLE-US-00001 TABLE 1 Properties of the poly(anthranilamides) prepared in examples 1, 2 and 3 n n M.sub.n (from .sup.1H NMR) Example (theoretical) (from .sup.1H NMR) [g/mol] 1 200 264 31 500 2 60 73   8770 3 900 809 96 400

Example 4: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Hexamethylene-1,6-Diamine as Starter in Diphenyl Ether as Solvent

[0120] Isatoic anhydride, diphenyl ether and hexamethylene-1,6-diamine were sourced from Sigma-Aldrich (step (A)).

[0121] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 10 g of isatoic anhydride and 37 g of diphenyl ether were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.050 g of hexamethylene-1,6-diamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A suspension was obtained.

[0122] The molar mass M.sub.n was determined in accordance with formula (II) by means of .sup.1H NMR in D.sub.2SO.sub.4. 20 g of the poly(anthranilamide) suspension was dissolved in 20 mL of concentrated sulfuric acid. The precipitated solid (=diphenyl ether solvent) was removed by filtration (step (C)).

[0123] The filtered sulfuric acid solution was added to 300 mL of water (step (D)(ii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

Example 5: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Hexamethylene-1,6-Diamine as Starter in Diphenyl Ether as Solvent

[0124] The procedure was as in example 4, apart from the following differences:

[0125] 10 g isatoic anhydride, 37 g of diphenyl ether and 0.11 g of hexamethylene-1,6-diamine were used.

Example 6: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Hexamethylene-1,6-Diamine as Starter in Diphenyl Ether as Solvent

[0126] The procedure was as in example 4, apart from the following differences:

[0127] 20 g isatoic anhydride, 75 g of diphenyl ether and 0.015 g of hexamethylene-1,6-diamine were used.

Example 7: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Hexamethylene-1,6-Diamine as Starter in Diphenyl Ether as Solvent

[0128] The procedure was as in example 4, apart from the following differences:

[0129] 25 g isatoic anhydride, 140 g of diphenyl ether and 0.005 g of hexamethylene-1,6-diamine were used.

[0130] The table below compares the analytical results.

TABLE-US-00002 TABLE 2 Properties of the poly(anthranilamides) prepared in examples 4 to 7 m + n m + n M.sub.n (from .sup.1H NMR) Example (theoretical) (from .sup.1H NMR) [g/mol] 4   200 131  15 820 5   60  49  5 970 6 1 000 982 117 100 7 2 500 1 918   228 540

Example 8: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in Ethylmethylimidazolium Diethylphosphate (EMIM-DEP) as Solvent at 180° C.

[0131] Isatoic anhydride and ethylmethylimidazolium diethylphosphate (EMIM-DEP) were sourced from Sigma-Aldrich, and neopentylamine from ABCR (step (A)).

[0132] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 10 g of isatoic anhydride and 28 g of ethylmethylimidazolium diethylphosphate (EMIM-DEP) were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.010 g of neopentylamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A clear solution was obtained.

[0133] The poly(anthranilamide) solution was added to 300 mL of water (step (D)(iii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

Example 9: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Hexamethylene-1,6-Diamine as Starter in Ethylmethylimidazolium Diethylphosphate (EMIM-DEP) as Solvent at 150° C.

[0134] Isatoic anhydride, ethylmethylimidazolium diethylphosphate (EMIM-DEP) and hexamethylene-1,6-diamine were sourced from Sigma-Aldrich (step (A)).

[0135] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 6 g of isatoic anhydride and 16 g of ethylmethylimidazolium diethylphosphate (EMIM-DEP) were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.043 g of hexamethylene-1,6-diamine was introduced and the solution was stirred at 150° C. for 15 h (step (B)). A clear solution was obtained.

[0136] The poly(anthranilamide) solution was added to 300 mL of water (step (D)(iii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

[0137] In this experiment, the completeness of the elimination of CO.sub.2 was checked by weighing the solution prior to precipitation of the product. In the case of complete CO.sub.2 elimination, a mass of the resultant solution of 4.42 g would have been expected. A mass of 4.73 g was found, which corresponds to largely complete CO.sub.2 elimination within the scope of measurement accuracy.

Example 10: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in N-Methyl-2-Pyrrolidone (NMP) as Solvent

[0138] Isatoic anhydride and N-methyl-2-pyrrolidone (NMP) were sourced from Sigma-Aldrich, and neopentylamine from ABCR (step (A)).

[0139] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 1 g of isatoic anhydride and 4.5 g of N-methyl-2-pyrrolidone (NMP) were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.001 g of neopentylamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A suspension was obtained.

[0140] The molar mass M.sub.n was determined in accordance with formula (II) by means of .sup.1H NMR in D.sub.2SO.sub.4.

[0141] 1 g of the poly(anthranilamide) suspension was dissolved in 1 mL of concentrated sulfuric acid. The precipitated solid (=diphenyl ether solvent) was removed by filtration (step (C)).

[0142] The filtered sulfuric acid solution was added to 15 mL of water (step (D)(ii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

Example 11: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in 1,3-Dimethyl-2-Imidazolidinone (DMI) as Solvent

[0143] Isatoic anhydride and 1,3-dimethyl-2-imidazolidinone (DMI) were sourced from Sigma-Aldrich, and neopentylamine from ABCR (step (A)).

[0144] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 1 g of isatoic anhydride and 4.5 g of 1,3-dimethyl-2-imidazolidinone (DMI) were weighed in. Nitrogen was introduced at 10 L/h, for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.001 g of neopentylamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A suspension was obtained.

[0145] The molar mass M.sub.n was determined in accordance with formula (II) by means of .sup.1H NMR in D.sub.2SO.sub.4.

[0146] 1 g of the poly(anthranilamide) suspension was dissolved in 1 mL of concentrated sulfuric acid. The precipitated solid (=diphenyl ether solvent) was removed by filtration (step (C)).

[0147] The filtered sulfuric acid solution was added to 15 mL of water. The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h (step (D)).

[0148] The table below compares the analytical results.

TABLE-US-00003 TABLE 3 Properties of the poly(anthranilamides) prepared in examples 10 and 11 n n M.sub.n (from .sup.1H NMR) Example (theoretical) (from .sup.1H NMR) [g/mol] 10 200 130 15 660 11 200 193 23 400

Example 12: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in a Mixture of N-Methyl-2-Pyrrolidone (NMP) and Ethylmethylimidazolium Diethylphosphate (EMIM-DEP) as Solvent

[0149] Isatoic anhydride, N-methyl-2-pyrrolidone (NMP) and ethylmethylimidazolium diethylphosphate (EMIM-DEP) were sourced from Sigma-Aldrich, and neopentylamine from ABCR (step (A)).

[0150] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 1.5 g of isatoic anhydride, 4.5 g of N-methyl-2-pyrrolidone (NMP) and 0.236 g of ethylmethylimidazolium diethylphosphate (EMIM-DEP) were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.001 g of neopentylamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A suspension was obtained.

[0151] The molar mass M.sub.n was determined in accordance with formula (II) by means of .sup.1H NMR in D.sub.2SO.sub.4.

[0152] 1 g of the poly(anthranilamide) suspension was dissolved in 1 mL of concentrated sulfuric acid. The precipitated solid (=diphenyl ether solvent) was removed by filtration (step (C)).

[0153] The filtered sulfuric acid solution was added to 15 mL of water (step (D)(ii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

Example 13: Preparation of Poly(Anthranilamide) by Ring-Opening Polymerization of Isatoic Anhydride as Monomer and Neopentylamine as Starter in a Mixture of 1,3-Dimethyl-2-Imidazolidinone (DMI) and Ethylmethylimidazolium Diethylphosphate (EMIM-DEP) as Solvent

[0154] Isatoic anhydride, 1,3-dimethyl-2-imidazolidinone (DMI) and ethylmethylimidazolium diethylphosphate (EMIM-DEP) were sourced from Sigma-Aldrich, and neopentylamine from ABCR (step (A)).

[0155] A 100 mL four-neck flask was equipped with a distillation system, precision glass stirrer, temperature probe, nitrogen feed and gas exit/gas outlet with pressure relief valve. Subsequently, 1.5 g of isatoic anhydride, 4.5 g of 1,3-dimethyl-2-imidazolidinone (DMI) and 0.236 g of ethylmethylimidazolium diethylphosphate (EMIM-DEP) were weighed in. Nitrogen was introduced at 10 L/h for 20 minutes, in the course of which the mixture was heated to 40° C. while stirring at 300 rpm. Subsequently, 0.001 g of neopentylamine was introduced and the solution was stirred at 180° C. for 15 h (step (B)). A suspension was obtained.

[0156] The molar mass M.sub.n was determined in accordance with formula (II) by means of .sup.1H NMR in D.sub.2SO.sub.4.

[0157] 1 g of the poly(anthranilamide) suspension was dissolved in 1 mL of concentrated sulfuric acid. The precipitated solid (=diphenyl ether solvent) was removed by filtration (step (C)).

[0158] The filtered sulfuric acid solution was added to 15 mL of water (step (D)(ii)). The precipitated solid was isolated by filtration and then dried at 160° C. at 0.05 bar for 24 h.

[0159] The table below compares the analytical results.

TABLE-US-00004 TABLE 4 Properties of the poly (anthranilamides) prepared in examples 9 and 10 n n M.sub.n (from .sup.1H NMR) Example (theoretical) (from .sup.1H NMR) [g/mol] 12 200 220 26 260 13 200 284 33 680