JP3725974B2 - Method for producing catalyst solution for polyester production - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a catalyst used for producing a polyester, and more particularly to a method for producing a catalyst solution in which crystalline germanium dioxide is dissolved in ethylene glycol.
[0002]
[Prior art]
A polyester composed of an aromatic dicarboxylic acid and a glycol is generally a low polymer obtained by a direct esterification reaction between an aromatic dicarboxylic acid and a glycol or a transesterification reaction between a lower alkyl ester of an aromatic dicarboxylic acid and a glycol. It is produced by a one-stage reaction and a second-stage reaction in which the resulting low polymer is subjected to polycondensation under reduced pressure at a higher temperature than the first stage. For example, polyethylene terephthalate is produced by esterifying terephthalic acid and ethylene glycol at 200 to 260 ° C. and then polycondensing at 260 to 300 ° C.
[0003]
In order to produce polyester efficiently, catalysts that promote these reactions, especially the second stage reaction, have been developed, and various metal catalysts such as antimony, titanium, and germanium are known. ing.
Among these catalysts, germanium-based catalysts are known to produce polyesters with good color tone, and USP 2578660 describes the use of germanium dioxide, which is the most readily available and easy to handle.
However, crystalline germanium dioxide, which is readily available, has a very low solubility in the reaction mixture, so that a large amount of addition is necessary to obtain a sufficient catalytic effect, and an undissolved catalyst is present in the resin. Therefore, there is a problem that the filtration device is blocked during the melt molding or the products such as fibers and films are clouded.
[0004]
In order to solve such a problem, a method using germanium dioxide treated at a high temperature (about 200 ° C.) in ethylene glycol, a method using germanium dioxide having a small particle diameter, and the like have been proposed. The fact is that the problems caused by the low solubility of germanium dioxide have not been completely improved.
For these reasons, when using germanium dioxide, a method of adding various additives to the reaction mixture together with germanium dioxide, a method of using a catalyst solution in which germanium dioxide is dissolved in advance by a solubilizer, etc., a readily soluble derivative of germanium dioxide The method of using it after conversion is adopted.
[0005]
For example, Japanese Patent Publication No. 48-33036 discloses a method in which a carbonate of Li, Na or K is added to a reaction mixture together with germanium dioxide. Japanese Patent Publication No. 47-15703 discloses a treatment in which germanium dioxide is treated with a nitrogen-containing compound. JP-A 51-68696 discloses a method using a liquid, and a method using an easily soluble germanium dioxide derivative such as tetraalkylammonium metagermanate as a catalyst.
However, these methods have a problem that the polyester resin is likely to be colored because a basic compound is added to the reaction mixture together with germanium dioxide.
[0006]
As a method for reducing the basic compound that causes this coloring, JP-A-6-329778 discloses that germanium dioxide is heated together with a compound that is an ammonia generating source such as ammonium carbonate in ethylene glycol to dissolve germanium dioxide. A method is described in which ammonia in a solution is removed to 500 ppm or less by nitrogen bubbling or the like while heating is continued. However, in this method, there is no change in using a large amount of a compound serving as an ammonia generation source, and if the removal is not sufficiently performed, the polyester resin may be colored. Further, it is described that germanium dioxide which has been dissolved is precipitated when ammonia is excessively removed to be 30 ppm or less. That is, in this method, it is necessary to control the concentration of ammonia in the catalyst solution within a very narrow range, but there is a problem that it is difficult to control such reaction conditions.
[0007]
A method of treating germanium dioxide with an organic carboxylic acid instead of such a basic compound is described in Japanese Patent Publication No. 47-42756. The organic carboxylic acid is an ester similar to an aromatic carboxylic acid such as terephthalic acid. Therefore, there is a problem that it is incorporated into the polyester resin and affects the quality.
[0008]
On the other hand, as a method for preparing a high-concentration solution of germanium dioxide without using a solubilizer, Japanese Patent Publication No. 54-22234 discloses a method in which germanium dioxide is dissolved by heating in glycol and concentrated. The gazette describes a method using amorphous germanium dioxide having relatively good solubility.
However, in the method of heating and concentrating, since the solubility of germanium dioxide is low, it is necessary to distill most of the glycol in order to obtain a solution having the same concentration as when a solubilizer is used, There was a problem that the efficiency was very low.
Further, the method using amorphous germanium dioxide has a problem that amorphous germanium dioxide is more expensive and disadvantageous in cost than crystalline germanium dioxide.
[0009]
[Problems to be solved by the invention]
In order to solve the above-mentioned problems of the prior art, the present inventor has conducted detailed studies over a long period of time on the dissolution reaction of germanium dioxide in ethylene glycol. As a result, the reaction system of water generated by the reaction at the time of dissolution It is found that there is a close relationship with the germanium concentration of the catalyst solution that can be removed from the catalyst, and that the addition of a small amount of a basic amino compound accelerates the progress of the dissolution reaction and suppresses the formation of by-products. The invention has been completed.
[0010]
[Means for Solving the Problems]
The present invention includes the following inventions.
(1) A method for producing a germanium catalyst solution for polyester production, wherein water produced by the reaction is removed from the reaction solution in a reaction in which crystalline germanium dioxide is dissolved in ethylene glycol by heating.
(2) The method according to (1) above, wherein the amount of water removed from the reaction solution is 0.5 to 20 times moles of dissolved crystalline germanium dioxide.
(3) The method as described in said (1) or (2) which removes the water to produce | generate as water vapor | steam.
(4) The crystalline water is dissolved under boiling conditions of ethylene glycol, and the generated water is removed by separating the generated water vapor and ethylene glycol vapor using a distillation tower. the method of.
(5) The method according to (1) or (2), wherein water to be generated is removed using an inert gas stream.
(6) The method according to any one of (1) to (5) above, wherein 0.001 to 10 mol% of a basic amino compound of germanium dioxide coexists in the dissolution reaction of crystalline germanium dioxide.
(7) The method according to any one of (1) to (6), wherein ethylene glycol is added to the reaction solution during the reaction.
(8) The method according to (7) above, wherein ethylene glycol accompanying the water to be generated is removed from the reaction solution and added to the reaction solution.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
In the present invention, in the reaction in which crystalline germanium dioxide is dissolved in ethylene glycol by heating, it is necessary to remove water produced by the reaction from the reaction solution.
The crystalline germanium dioxide used in the present invention may be either tetragonal or hexagonal germanium dioxide, but hexagonal germanium dioxide is preferably used.
[0012]
The amount of ethylene glycol used is usually from 1 to 200 parts by weight, preferably from 2 to 50 parts by weight, more preferably from 6 to 35 parts by weight, based on 1 part by weight of crystalline germanium dioxide during preparation. Although reaction temperature changes with pressures at the time of reaction, it is 150-300 degreeC normally, Preferably it is 190-280 degreeC, More preferably, it is 190-260 degreeC. The pressure during the reaction is not particularly limited as long as water generated by the reaction can be removed from the reaction solution. If the amount of water to be removed is small, the amount of germanium dioxide dissolved will be small.On the other hand, if this amount is large, the amount of by-product, mainly diethylene glycol, tends to be large. It is 0.5-20 times mole normally with respect to the melt | dissolved crystalline germanium dioxide, Preferably it is 1-10 times mole, More preferably, it is 2-8 times mole. It is also preferable to remove organic substances such as acetaldehyde having a boiling point lower than that of ethylene glycol together with water.
[0013]
As a method for removing generated water from the reaction solution, a method for removing it as water vapor and a method for removing it using an inert gas stream are preferable. In the case of removing the generated water as water vapor, it is particularly preferable that the crystalline germanium dioxide dissolution reaction is carried out under the boiling conditions of ethylene glycol, and the generated water vapor and ethylene glycol vapor are separated using a distillation column. . The ethylene glycol thus separated is preferably returned to the reaction solution. Further, instead of returning the separated ethylene glycol to the reaction solution, new ethylene glycol may be added to the reaction solution. In addition, when the generated water is removed using an inert gas stream, examples of the inert gas include nitrogen gas and argon gas. The flow rate is not particularly limited, but is usually 0.1 per 100 ml of the reaction solution. In the range of ~ 200 ml / min.
[0014]
In addition, by allowing the basic amino compound to coexist in the dissolution reaction, the progress of the dissolution reaction can be promoted and the formation of by-products can be further suppressed. The usage-amount of a basic amino compound is 0.001-10 mol% normally with respect to germanium dioxide, Preferably it is 0.05-5 mol%. In addition, when there is too much usage-amount of a basic amino compound, when the obtained catalyst solution is used for manufacture of polyester, it will become easy to generate | occur | produce coloring of polyester. Examples of the basic amino compound used herein include basic ammonia, various organic amines, quaternary ammonium compounds, and the like, and preferably trimethylamine, triethylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, trimethylamine, and the like. Tertiary aliphatic or alicyclic amines such as n-hexylamine, N-methylmorpholine, N-methylpyrrolidine, N-methylpiperidine; pyridine, pyrrole, N, N-dimethylaniline, N, N-diethylaniline, etc. Tertiary aromatic amines; quaternary ammonium hydroxides such as tetramethylammonium hydroxide and tetraethylammonium hydroxide are used.
[0015]
The catalyst solution obtained by the present invention can be used as a catalyst for polyester production as it is, but when there are undissolved materials such as undissolved crystalline germanium dioxide, ordinary methods such as filtration and decantation are used. It is preferable to remove the undissolved material by.
[0016]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated more concretely, the scope of the present invention is not limited to these Examples.
(Example 1)
Crystallized germanium dioxide (hexagonal) 20.0 g (192 mmol) and ethylene glycol 170.0 g in a 300 ml three-necked flask equipped with an Oldershaw type column (25 mmφ × 3 plate), a moisture determination receiver, a condenser and a stirrer (magnetic stirrer) Was immersed in a 205 ° C. oil bath under a nitrogen stream (10 ml / min) and heating was started. Reflux started in about 20 minutes. The bath temperature was maintained at 205 ° C. for 1 hour from the start of reflux, and then heated to 220 ° C. over 5 hours. The bath temperature was maintained at 220 ° C. for 1 hour, and then cooled to 90 ° C. over about 1 hour. Between the start of heating and the end of cooling, 21.2 g (water content: 8.7 g, 483 mmol) was distilled from the upper part of the Oldershaw column.
[0017]
When the white turbid reaction liquid was filtered while maintaining at 80 ° C. or higher, 162.0 g of a colorless transparent filtrate was obtained. As a result of analysis, the filtrate contained 6.67 wt% (149 mmol) of germanium (as metal germanium), 9.0 wt% of diethylene glycol, and 0.37 wt% of water.
The residue was washed with a small amount of heated (60 ° C.) ethylene glycol and dried under reduced pressure at 100 ° C. · 1.32 × 10 ⁻³ MPa to recover 4.1 g of undissolved germanium dioxide.
[0018]
(Example 2)
When the same operation as in Example 1 was performed except that the holding time at 220 ° C. was changed to 6 hours after the temperature increase, the following results were obtained.
Filtrate yield: 167.3 g
Analysis results: germanium (as metal germanium) 7.94 wt% (183 mmol), diethylene glycol 18.6 wt%, water 0.21 wt%
Distillate volume: 15.6 g (water content: 12.3 g, 683 mmol)
Germanium dioxide recovery: 1.12 g
[0019]
(Example 3)
In a 200 ml three-necked flask equipped with an Oldershaw type column (25 mmφ × 3 plate), a moisture determination receiver, a condenser and a stirrer (magnetic stirrer), 25.0 g (239 mmol) of crystalline germanium dioxide (hexagonal crystal) and 159.4 g of ethylene glycol Was immersed in a 205 ° C. oil bath under a nitrogen stream (10 ml / min) and heating was started. Reflux started in about 25 minutes. The bath temperature was raised from 205 ° C. to 220 ° C. over 1 hour from the start of reflux, and further raised to 226 ° C. over 3.5 hours. Hold at 226 ° C. for 3 hours and cool to 90 ° C. overnight. Between the start of heating and the end of cooling, 20.6 g (water content: 11.6 g, 644 mmol) was distilled from the top of the Oldershaw column.
When the white turbid reaction liquid was filtered while maintaining at 80 ° C. or higher, 158.4 g of a colorless and transparent filtrate was obtained. As a result of analysis, the filtrate contained 9.40 wt% (205 mmol) of germanium (as metal germanium) and 13.6 wt% of diethylene glycol.
Further, the residue was washed with a small amount of heated (60 ° C.) ethylene glycol and dried under reduced pressure at 100 ° C. · 1.32 × 10 ⁻³ MPa to recover 2.9 g of undissolved germanium dioxide.
[0020]
(Example 4)
When the same operation as in Example 1 was performed except that 10.0 g (95.6 mmol) of crystalline germanium dioxide (hexagonal crystal) was used, the following results were obtained.
Filtrate yield: 159.2 g
Analysis results: germanium (as metal germanium) 4.12 wt% (90.3 mmol), diethylene glycol 11.7 wt%, water 0.18 wt%
Distillate volume: 17.1 g (water content: 3.6 g, 200 mmol)
Germanium dioxide recovery: 0.41 g
[0021]
(Example 5)
Use 10.0 g (95.6 mmol) of crystalline germanium dioxide (hexagonal crystal), add 0.11 g of triethylamine (1.10 mol% of germanium dioxide) as a dissolution accelerator, and maintain at 220 ° C. for 2 hours after the temperature rise. When heated and dissolved under the same conditions as in Example 1 except for the above, the whole amount of germanium dioxide added was dissolved, and a colorless and almost transparent reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction solution yield: 164.7 g
Analysis results: germanium (as metal germanium) 4.15 wt% (94.1 mmol), diethylene glycol 8.1 wt%, water 0.17 wt%
Distillate amount: 10.6 g (water content: 7.50 g, 417 mmol)
[0022]
(Example 6)
Heat dissolution was performed under the same conditions as in Example 5 except that 0.10 g of triisopropylamine (0.73 mol% of germanium dioxide) was used as a dissolution accelerator. As a result, the total amount of germanium dioxide added was dissolved and colorless. An almost transparent reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction liquid yield: 167.0g
Analysis results: germanium (as metal germanium) 4.12 wt% (94.8 mmol), diethylene glycol 6.9 wt%, water 0.21 wt%
Distillate volume: 8.1 g (water content: 6.9 g, 383 mmol)
[0023]
(Example 7)
When dissolution by heating was carried out under the same conditions as in Example 5 except that 0.10 g of tri-n-butylamine (0.57 mol% of germanium dioxide) was used as a dissolution accelerator, the total amount of germanium dioxide added was dissolved and colorless. An almost transparent reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction liquid yield: 166.4g
Analysis results: germanium (as metal germanium) 4.10 wt% (94.0 mmol), diethylene glycol 7.3 wt%, water 0.14 wt%
Distillate volume: 9.2 g (water content: 7.3 g, 406 mmol)
[0024]
(Example 8)
Heat dissolution was performed under the same conditions as in Example 5 except that 0.10 g of triisobutylamine (0.63 mol% of germanium dioxide) was used as a dissolution accelerator. As a result, the entire amount of germanium dioxide added was dissolved and colorless. An almost transparent reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction solution yield: 162.3 g
Analysis results: germanium (as metal germanium) 4.25 wt% (95.0 mmol), diethylene glycol 6.9 wt%, water 0.18 wt%
Distillate volume: 12.4 g (water content: 7.5 g, 417 mmol)
[0025]
Example 9
Heat dissolution was performed under the same conditions as in Example 5 except that 0.10 g of tri-n-hexylamine (0.39 mol% of germanium dioxide) was used as a dissolution accelerator, and the total amount of germanium dioxide added was dissolved. A colorless and almost transparent reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction solution yield: 165.0 g
Analysis results: germanium (as metal germanium) 4.18 wt% (95.0 mmol), diethylene glycol 9.8 wt%, water 0.14 wt%
Distillate volume: 10.1 g (water content: 7.5 g, 417 mmol)
[0026]
(Example 10)
When dissolution by heating was carried out under the same conditions as in Example 5 except that 0.10 g of N-methylmorpholine (1.00 mol% of germanium dioxide) was used as a dissolution accelerator, the entire amount of germanium dioxide added was dissolved and colorless. An almost transparent reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction liquid yield: 160.8g
Analysis results: germanium (as metal germanium) 4.30 wt% (95.2 mmol), diethylene glycol 9.2 wt%, water 0.13 wt%
Distillate volume: 13.1 g (water content: 10.0 g, 556 mmol)
[0027]
(Example 11)
When heated and dissolved under the same conditions as in Example 5 except that 0.10 g of pyridine (1.58 mol% of germanium dioxide) was used as a dissolution accelerator, the entire amount of germanium dioxide added was dissolved and colorless and almost transparent A reaction solution was obtained. The analysis results of the reaction solution are shown below.
Reaction liquid yield: 167.6g
Analysis results: germanium (as metal germanium) 4.14 wt% (95.6 mmol), diethylene glycol 6.0 wt%, water 0.18 wt%
Distillate volume: 7.5 g (water content: 6.3 g, 350 mmol)
[0028]
(Example 12)
The solution was heated and dissolved under the same conditions as in Example 5 except that 0.31 g of a 15% tetramethylammonium hydroxide aqueous solution (0.52 mol% of germanium dioxide) was used as a dissolution accelerator, and the total amount of germanium dioxide added. Dissolved, and a colorless and almost transparent reaction liquid was obtained. The analysis results of the reaction solution are shown below.
Reaction solution yield: 164.9 g
Analysis results: germanium (as metal germanium) 4.20 wt% (95.4 mmol), diethylene glycol 7.4 wt%, water 0.11 wt%
Distillate amount: 9.9 g (water content: 7.3 g, 406 mmol)
[0029]
(Example 13)
Heat dissolution was performed under the same conditions as in Example 5 except that 0.32 g of a 20% tetraethylammonium hydroxide aqueous solution (0.46 mol% of germanium dioxide) was used as a dissolution accelerator, and the total amount of germanium dioxide added was A colorless and almost transparent reaction solution was obtained by dissolution. The analysis results of the reaction solution are shown below.
Reaction solution yield: 166.3 g
Analysis results: germanium (as metal germanium) 4.03 wt% (92.3 mmol), diethylene glycol 7.8 wt%, water 0.12 wt%
Distillate amount: 8.7 g (water content: 6.9 g, 383 mmol)
[0030]
(Example 14)
15.0 g (144 mmol) of crystalline germanium dioxide, 0.44 g of 20% tetraethylammonium hydroxide aqueous solution (0.42 mol% of germanium dioxide) was used as a dissolution accelerator, and the temperature was raised at 220 ° C. When the same operation as in Example 1 was performed except that the holding time was 6 hours, the following results were obtained.
Filtrate yield: 165.5 g
Analysis results: germanium (as metal germanium) 6.04 wt% (138 mmol), diethylene glycol 13.8 wt%, water 0.08 wt%
Distillate volume: 12.8 g (water content: 10.3 g, 572 mmol)
Germanium dioxide recovery: 0.04g
[0031]
(Example 15)
The following results were obtained when the same operation as in Example 1 was performed except that the nitrogen stream was set at 100 ml / min and the bath temperature was kept constant at 120 ° C. for 20 hours.
Filtrate yield: 162.2 g
Analysis results: germanium (as metal germanium) 0.65 wt% (14.5 mmol), diethylene glycol 0.09 wt%, water 0.21 wt%
Distillate volume: 0.29 g (water content: 0.27 g, 15 mmol)
Germanium dioxide recovery: 18.36 g
[0032]
(Example 16)
When the same operation as in Example 15 was performed except that the bath temperature was kept constant at 150 ° C. for 20 hours, the following results were obtained.
Filtrate yield: 164.1 g
Analysis results: germanium (as metal germanium) 0.76 wt% (17.2 mmol), diethylene glycol 0.17 wt%, water 0.18 wt%
Distillate volume: 0.49 g (water content: 0.38 g, 21 mmol)
Germanium dioxide recovery: 18.03 g
[0033]
(Example 17)
An esterification reaction was carried out by a conventional method using 100 parts by weight of terephthalic acid and 44.8 parts by weight of ethylene glycol (reaction temperature 260 ° C., pressure 1.7 kg / cm ² · G, 6 hours).
To the esterification reaction product obtained above, 0.285 parts by weight of the catalyst solution (colorless transparent filtrate) obtained in Example 1 (0.019 parts by weight as metal germanium), 0.5 parts by weight of ethylene glycol Then, 0.029 part by weight of trimethyl phosphate was added and liquid phase polycondensation was performed for 2.5 hours under the conditions of a reaction temperature of 280 ° C. and a pressure of 3 torr to obtain a polyester chip having an intrinsic viscosity of 0.55 dl / g.
The polyester chip obtained by the liquid phase polycondensation reaction was subjected to a solid phase polymerization reaction at 215 ° C. for 20 hours under a nitrogen stream to obtain a polyester chip having an intrinsic viscosity of 0.76 dl / g. The density of this polyester chip is 1.401 g / cm ³ , and the color tone measured with a 45 ° diffusion type color difference meter (Suga Test Instruments, SC-2-CH type) is L value (lightness): 91.0, a value ( + Red, -green): -2.2, b value (+ yellow, -blue): +1.0.
[0034]
(Comparative Example 1)
A 100 ml three-necked flask equipped with a condenser and a stirrer (magnetic stirrer) was charged with 2.00 g (19.2 mmol) of crystalline germanium dioxide (hexagonal crystal) and 50.0 g of ethylene glycol, and placed in an oil bath at 120 ° C. in a nitrogen atmosphere. Immersion was started and heating was started. After heating for 8 hours, the reaction solution was cooled to 40 ° C. and filtered to obtain 49.7 g of a colorless and transparent filtrate. As a result of analysis, the filtrate contained 0.28 wt% germanium (as metal germanium), 0.02 wt% diethylene glycol, and 2.03 wt% water.
The residue was washed with a small amount of heated (60 ° C.) ethylene glycol and dried under reduced pressure at 100 ° C. · 1.32 × 10 ⁻³ MPa to recover 1.79 g of undissolved germanium dioxide.
[0035]
(Comparative Example 2)
When the same operation as in Comparative Example 1 was performed except that 1.00 g (9.6 mmol) of crystalline germanium dioxide (hexagonal crystal) was used and the heating time was changed to 20 hours, the following results were obtained.
Filtrate yield: 49.9 g
Analysis results: germanium (as metal germanium) 0.11 wt%, diethylene glycol 0.01 wt%, water 2.34 wt%
Germanium dioxide recovery: 0.92g
[0036]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to this invention, the catalyst solution for polyester manufacture with a high germanium density | concentration can be manufactured using an easily available and cheap crystalline germanium dioxide.

Claims (9)

In the reaction in which crystalline germanium dioxide is heated and dissolved in ethylene glycol, the water produced by the reaction is removed from the reaction solution using a distillation tower in the absence of ammonia , and the produced water is removed from the reaction solution. A method for producing a germanium catalyst solution for producing polyester, wherein the accompanying ethylene glycol is separated and added to a reaction solution .   The method according to claim 1, wherein the amount of water removed from the reaction solution is 0.5 to 20 times mol of dissolved crystalline germanium dioxide.   The method according to claim 1 or 2, wherein the produced water is removed as water vapor.   The method according to claim 3, wherein the dissolution of crystalline germanium dioxide is carried out under boiling conditions of ethylene glycol, and the generated water is removed by separating the generated water vapor and ethylene glycol vapor using a distillation tower.   The method according to claim 1 or 2, wherein water to be generated is removed using an inert gas stream.   The method according to any one of claims 1 to 5, wherein 0.001 to 10 mol% of an organic amine or a quaternary ammonium compound of germanium dioxide coexists in a dissolution reaction of crystalline germanium dioxide.   The method according to claim 6, wherein the organic amine or the quaternary ammonium compound is a tertiary aliphatic or alicyclic amine, a tertiary aromatic amine, or a quaternary ammonium hydroxide.   An organic amine or a quaternary ammonium compound is trimethylamine, triethylamine, triisopropylamine, tri-n-butylamine, triisobutylamine, tri-n-hexylamine, N-methylmorpholine, N-methylpyrrolidine, N-methylpiperidine, pyridine, pyrrole, 7. A process according to claim 6 selected from N, N-dimethylaniline, N, N-diethylaniline, tetramethylammonium hydroxide and tetraethylammonium hydroxide. The method according to any one of claims 1 to 8 , wherein the reaction of heating and dissolving crystalline germanium dioxide in ethylene glycol is carried out at 150 to 300 ° C.