JP2932689B2 - Method for removing nitrogen compounds in cresols - Google Patents

Description

The present invention relates to a method for removing nitrogen compounds in cresols, which are useful as raw materials for pharmaceuticals, agricultural chemicals, dyes, antioxidants and the like.

<Problems to be solved by the prior art and the invention> o-, m-, p-cresol or a mixed cresol obtained by mixing them (hereinafter, these are collectively referred to as cresols) are obtained by alkylating them. Widely used as intermediates for medicines, agricultural chemicals, antioxidants, dyes, etc.

These cresols are industrially used after isomer separation according to the purpose. In this separation process, urea is used as a separating agent (distillation technique, March 1977, No. 4, pages 10 to 17). This urea is recovered after separation of the cresols and reused. In the recovery process, dimers and trimers of urea are partially generated, and cresol carbamate partially reacted with the cresols is recovered. Esters and the like are formed.

These nitrogen compounds derived from urea (hereinafter collectively referred to as nitrogen compounds) are lipophilic and sublimable, and decompose when heated, so that only cresols after separation are purified by distillation. , Cannot be removed.

Moreover, when these nitrogen compounds are present in the cresols, the catalyst used in the alkylation reaction of the cresols is poisoned and the reaction is inhibited, so that it is necessary to remove the nitrogen compounds contained in the cresols. .

As a general method of decomposing urea, a method of adding boric acid and heating at 200 to 600 ° C., a method of decomposing with nitrous acid, and the like are known, and these are applied to removal of nitrogen compounds in cresols. In the former case, the former is disadvantageous in that cresols themselves are deteriorated due to heating to a high temperature and the high heat is required, so that industrial implementation is difficult. In the latter, nitrosation reaction of cresols and the like are difficult to apply. Met.

As one method for improving such a problem, the present inventors heat-treat cresols containing these nitrogen compounds in the presence of a basic compound and water to obtain ammonia,
A method of decomposing into carbon dioxide or the like was proposed (Japanese Patent Laid-Open No. 02-0768
33).

An object of the present invention is to provide an industrially superior method for removing nitrogen compounds in cresols.

<Means for Solving the Problems> The present inventors have conducted intensive studies to solve the above problems, and as a result, a method of treating a nitrogen compound in cresols with an aqueous solution of a basic compound, followed by liquid separation and removal, and Further, the present inventors have found a method of treating the obtained cresols with an aqueous solution of an acidic compound, and thereafter separating the liquid, and have reached the present invention.

That is, the present invention provides a method for removing a nitrogen compound in cresols, which comprises treating cresols with an aqueous solution of a basic compound and then separating the solution, and treating the cresols with an aqueous solution of a basic compound, followed by separation. The present invention relates to a method for removing nitrogen compounds in cresols, which comprises treating the resulting cresols with an aqueous solution of an acidic compound, followed by liquid separation.

 Hereinafter, the present invention will be described in detail.

In the present invention, specific examples of the basic compound to be used include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide, magnesium hydroxide, and calcium hydroxide, and alkaline earth metal hydroxides. Things and
Alkali metal carbonates such as sodium carbonate and potassium carbonate, alkaline earth metal carbonates, and alkali metal oxides such as sodium oxide, potassium oxide and calcium oxide;
Alkaline earth metal oxides and the like can be mentioned. Of these, sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate are particularly preferably used.

The concentration of the aqueous solution of the basic compound varies depending on the amount of the nitrogen compound contained in the cresol, but is usually in the range of 0.1 to 20% by weight, preferably 1 to 15% by weight.

Further, the amount of the aqueous solution based on the cresols is usually 5 to 5.
It is in the range of 500% by weight, preferably 10-300% by weight.

In the present invention, the use of an organic solvent is effective in improving the liquid separation property. Examples of the organic solvent include aromatic hydrocarbons such as toluene and xylene, hexane, heptane, and aliphatic solvents such as cyclohexane. Hydrocarbons and the like can be mentioned.

The amount of the organic solvent to be used is not particularly limited, but is usually in the range of 0.5 to 9 weight ratio, preferably 1 to 5 weight ratio, based on cresols.

The temperature for the treatment and liquid separation is 20 to 100 ° C., preferably 30 to 80 ° C., and the time for the treatment and liquid separation is not particularly limited.

Examples of a method of treating with an aqueous solution of a basic compound and then separating the liquid include a usual extraction method.

Specific extraction methods include, for example, a continuous method and a batch method.

The continuous method is a method for extracting nitrogen compounds in cresols by continuously feeding a solution of a cresol or an organic solvent thereof and an aqueous solution of a basic compound using a mixer-settler type or a multi-stage extraction device of a tower type. , The batch method
This is a method in which a solution of cresols or an organic solvent thereof and an aqueous solution of a basic compound are charged, stirred, and then allowed to stand for separation.

In both the continuous method and the batch method, the number of extraction stages or the number of extractions can be determined based on the amount of the nitrogen compound in the cresols before treatment and the final target concentration.

In removing the nitrogen compound contained in the cresols of the present invention, an aqueous solution of an acidic compound before or after separation with an aqueous solution of a basic compound, if necessary according to the concentration of the target nitrogen compound as a final target And then liquid separation can be performed. In particular, when the cresols are treated with an aqueous solution of a basic compound and then separated, and then treated with an aqueous solution of an acidic compound and then separated, the removal of nitrogen compounds in the cresols is most efficiently performed. preferable.

Specific examples of the acidic compound include hydrochloric acid, sulfuric acid, acetic acid, and phosphoric acid, and among them, hydrochloric acid and sulfuric acid are particularly preferable.

The concentration of the aqueous solution of the acidic compound varies depending on the amount of the nitrogen compound contained in the cresol, but is usually in the range of 0.1 to 20% by weight, preferably 1 to 15% by weight, based on the cresol. The amount of the aqueous solution is usually 5 to
It is in the range of 500% by weight, preferably 10-300% by weight.

The temperature for the treatment and liquid separation is 20 to 100 ° C., preferably 30 to 80 ° C., and the time for the treatment and liquid separation is not particularly limited.

The method of treating with an aqueous solution of an acidic compound and then separating the solution can also be performed by, for example, an extraction method such as a continuous method or a batch method.

However, in the case of using a multi-stage extraction device of a mounted type, it is difficult to use an acid in terms of material.Therefore, use a mixer-settler type alone, or perform treatment with a basic compound and liquid separation in a mounted type. The treatment with an acidic compound and the liquid separation may be performed in a mixer-settler type.

The thus obtained solution of cresols or their organic solvents is further distilled off the solvent or the like by rectification and then simple distilled to obtain high-quality cresol containing almost no nitrogen compounds.

In addition, since the present invention uses a basic compound, a part of the cresols becomes a phenolate and dissolves in a basic aqueous phase, so that the basic aqueous phase or a mixed liquid of the basic aqueous phase and the acidic aqueous phase is used. Adjust PH = 7 ~ 8, toluene, xylene,
Cresols can be recovered by extraction with a solvent such as an aromatic or aliphatic hydrocarbon such as hexane, heptane and cyclohexane.

<Effects of the Invention> According to the present invention, nitrogen compounds contained in cresols can be almost completely removed industrially advantageously. As a result, catalyst poisoning in the alkylation reaction of cresols can be avoided, and the industrial effect is great.

<Example> Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the examples.

Example 1 100 parts by weight of a toluene solution containing 30% of cresol at an m / p ratio of 30/70 were mixed with 50 parts by weight of a 10% aqueous solution of sodium carbonate, a 10% aqueous solution of sulfuric acid, and water in this order at 50 ° C. for 1 part each. Extraction was carried out for 5 minutes each time, and liquid separation was carried out. As a result, the nitrogen compound present at 65.7 ppm as the total nitrogen content in the raw material was finally reduced to 1.8 ppm. Table 1 shows the results.

Example 2 100 parts by weight of cresols (m / p ratio = 30/70) in toluene (30% by weight cresol content) were treated twice with 50 parts by weight of 10% aqueous sodium carbonate solution and 10% aqueous sulfuric acid solution, respectively. 50
Extraction was performed at 5 ° C. for 5 minutes, and liquid separation was performed. Thereafter, the material was washed with water, and the nitrogen compound present at 178.2 ppm as the total nitrogen content in the raw material was finally reduced to 1.9 ppm. Table 2 shows the results.

Example 3 An experiment was conducted in the same manner as in Example 2 except that the basic compound was changed to a 5% aqueous sodium hydroxide solution.
Reduced to 8 ppm. Table 3 shows the results.

Example 4 A toluene solution (cresol content: 30% by weight) of cresols (m / p ratio = 30/70) was mixed with a 4% aqueous sodium hydroxide solution, a 4% aqueous sulfuric acid solution and water using a two-stage countercurrent mixer settler. Continuous extraction (total 6 stages) was performed. The supply amount is 5442 parts by weight / hour of a toluene solution of cresols, 448.3 parts by weight / hour of a 4% aqueous sodium hydroxide solution, and 45% by weight of a 4% aqueous sulfuric acid solution.
2.8 parts / hour, water 450.4 parts / hour, temperature is
Performed at 70 ° C. The residence time of each mixer was 5 minutes, and the residence time of each settler was 10 minutes. Nitrogen compounds present at 165.6 ppm as total nitrogen in the raw material were finally reduced to 0.9 ppm. Table 4 shows the results.

Example 5 A toluene solution (cresol content: 30% by weight) of cresols (m / p ratio = 30/70) was mixed with a 4% aqueous sodium hydroxide solution, a 4% aqueous sulfuric acid solution and water using a two-stage countercurrent mixer settler. Continuous extraction (total 6 stages) was performed. The supply amount was 320.54 parts by weight / hour of a toluene solution of cresols, 26.52 parts by weight / hour of a 4% aqueous sodium hydroxide solution, and 2% of a 4% aqueous sulfuric acid solution.
6.43 parts by weight / hour, water: 26.89 parts by weight / hour, and the temperature was 70 ° C. The residence time of each mixer was 5 minutes, and the residence time of each settler was 10 minutes. The obtained oil phase was decompressed in a 14-stage rectification column at 300 mmHg and reflux ratio.
The toluene was distilled off under the conditions of 0.2 and a reboiler temperature of 160 ° C. Furthermore, simple distillation was carried out at a reduced pressure of 10 mmHg and a temperature in the pot of 90 to 100 ° C. As a result of conducting a continuous experiment for 48 hours in all steps, the nitrogen compound present at 168.6 ppm as the total nitrogen content in the raw material was reduced to 0.5 ppm in the final distilled cresol. Table 5 shows the results.

Example 6 Using a five-stage countercurrent mixer settler at 480.35 parts by weight / hour of a toluene solution (cresol content: 30% by weight) of cresols (m / p ratio = 30/70), 40.05 wt. Parts / hour, and water was washed at 40.53 parts by weight / hour, and the oil phase was decompressed to 30 degrees by a 26-stage rectification column.
After rectification under the conditions of 0 mmHg, a reflux ratio of 0.2 and a reboiler temperature of 160 ° C., simple distillation was performed at a reduced pressure of 10 mmHg and a temperature in the kettle of 90 to 100 ° C.
As a result of performing all processes by a continuous method for 32 hours, the nitrogen compound contained in the raw material in the amount of 91.6 ppm in total was reduced to 0.9 ppm in the final distillation cresol. Table 6 shows the results.

Example 7 An experiment for extracting and recovering cresols dissolved in a basic and acidic aqueous phase obtained by removing nitrogen compounds in cresols was performed using a two-stage countercurrent extraction device of a mixer settler. Continuously feed 903 parts by weight / hour of a mixed aqueous phase of an acid and a base containing 5.63% by weight of cresols and 2086 parts by weight / hour of toluene, and control the pH to 7 to 8 with a 40% aqueous sulfuric acid solution at 50 ° C. 99.82% as a result of extraction with
Of cresols were recovered. Table 7 shows the results.

Reference Examples 1-3 Three cresols having different nitrogen contents (m / p ratio = 30/7)
0) 70% Tungstosilicic acid in 0.053 parts by weight
Parts by weight (0.0374 parts by weight as pure tungsten silicic acid) was added to the flask, and isobutylene was added at 50 ° C. to 0.5 parts by weight.
The reaction was carried out by blowing for hours. The reaction rate of 77.2% in cresol with total nitrogen content of 100ppm (before removing nitrogen compounds) is 99.36% in the case of using cresol with total nitrogen content of 1ppm
Up. Table 8 shows the results.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-62-164639 (JP, A) JP-A-2-76833 (JP, A) The Chemical Society of Japan, “New Laboratory Chemistry Course I ▼ Basic Operation I ”, published in 1978 by Maruzen Co., Ltd., page 295 (58) Fields investigated (Int.Cl. ⁶ , DB name) C07C 39 / 07,37 / 86 C07C 37/72

Claims (7)

(57) [Claims] 1. A method for removing nitrogen compounds in cresols, comprising treating cresols with an aqueous solution of a basic compound and then separating the liquid. 2. A nitrogen compound in cresols, wherein the cresols are treated with an aqueous solution of a basic compound and then separated, and the resulting cresols are further treated with an aqueous solution of an acidic compound and then separated. Removal method. 3. The method according to claim 1, wherein the treatment and separation temperature is 20 to 100 ° C. 4. The method according to claim 1, wherein the basic compound is sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate. 5. The method according to claim 1, wherein the concentration of the aqueous solution of the basic compound is 0.1 to 20% by weight. 6. The method according to claim 1, wherein an organic solvent is used for treating and separating the cresols.
The method described in. 7. The method according to claim 6, wherein an aromatic hydrocarbon or an aliphatic hydrocarbon is used as the organic solvent.