JPH0248542A - Recovery of 2,6-xylenol - Google Patents

Abstract

PURPOSE:To quickly extract and recover 2,6-xylenol with simple operation on an industrial scale at a low cost in high efficiency from an aqueous solution of an anionic surfactant containing 2,6-xylenol by using a specific organic solvent in the presence of an alkali metal salt. CONSTITUTION:A 4-12C saturated or unsaturated alcohol such as butanol or isobutanol is added together with an alkali metal salt such as Na2SO4, NaCl or K2CO3 to an aqueous solution of an anionic surfactant such as sodium dodecylsulfate containing 2,6-xylenol. The 2,6-xylenol is almost completely extracted and recovered to the alcohol layer by this process. The extract is concentrated by distilling off the alcohol solvent to obtain the objective compound useful as a raw material for 3,3',5,5'-tetramethylbiphenyl-4,4'-diol which is used as a component of polyester, polycarbonate, etc. The process enables the separation of 2,6-xylenol causing environmental pollution problem almost completely from water and reduced the steam consumption.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Application in Industry-E> The present invention relates to a method for recovering 2,6-xylenol contained in an aqueous surfactant solution.

The 2,6-xylenol recovered in the present invention is a 3,3-, 5.5-xylenol used as a component of polyester, polycarbonate, epoxy resin or as a stabilizer for petroleum products.
-tetramethylbiphenyl 4.4-diol (hereinafter referred to as
It is a useful compound used as a raw material for TMBP (abbreviated as TMBP).

On the other hand, 2.6-xylenol is a type of phenol, and wastewater containing 2.6-1r silenol poses a problem in terms of pollution control.

Conventional technology> As a method for recovering 2,6-xylenol contained in an aqueous surfactant solution, an alkaline earth metal salt is added,
A method of steam distillation is known (Japanese Unexamined Patent Publication No. 62-22
Publication No. 3139).

<Problems to be Solved by the Invention> In general, surfactant aqueous solutions have remarkable foaming properties and tend to emulsify organic solvents, so they are not easy to distill or extract. The above-mentioned recovery method is superior in that it enables steam distillation by suppressing foaming of the surfactant aqueous solution, making it easy to separate 2,6-xylenol from the surfactant aqueous solution. The disadvantage is that 4 to 5% of the 2,6-xylenol remains undistilled (for example Examples 1.2 and 3 of the above publication), resulting in a relatively high concentration of 2,6-xylenol-containing waste liquid. Also,
If residual 2.6-xylenol is to be forcibly distilled off, a large amount of water must be distilled due to the low vapor pressure of 2.6-xylenol, and a large amount of steam is required.

On the other hand, since the distillate is a mixture of 2.6-'i-silenol and water, further treatment such as extraction and recovery with an R-containing solvent is required.

Therefore, the method described above inevitably generates wastewater containing a relatively large amount of 2.6-4 silenol, consumes a large amount of steam, takes time to distill, and requires treatment of distillate. Therefore, there is a problem that operational efficiency is not good.

An object of the present invention is to provide an efficient and industrially advantageous method for recovering 2,6-xylenol from an aqueous surfactant solution, with almost no problems with wastewater treatment or large amounts of steam consumption. .

Means and Companion for Solving the Problems The present inventors have conducted intensive studies on a method for extracting and recovering 2,6-xylenol contained in an anionic surfactant aqueous solution using an organic solvent. That is, when an alkali metal salt coexists, a specific organic solvent, that is, a carbon number of 4 to 12
If a saturated or unsaturated alcohol is used, the synergistic effect of the alkali metal salt and alcohol will cause a clear interface to appear immediately after shaking has stopped, despite the presence of an anionic surfactant, and the organic layer and aqueous layer will be separated. Both have less emulsion, 2.
It was discovered that most of the 6-1r silenol can be quickly extracted and recovered in the alcohol layer, and the present invention was achieved.

That is, the present invention is characterized in that an aqueous solution of an anionic surfactant containing 2,6-xylenol is extracted using a saturated or unsaturated alcohol having 4 to 12 carbon atoms in the coexistence of an alkali metal salt. This is a method for recovering 2,6-xylenol.

Hereinafter, the configuration of the present invention will be explained in detail.

The 2,6-xylenol-containing aqueous surfactant solution used in the present invention is not particularly limited, but includes, for example, wastewater generated in a manufacturing process that handles 2,6-xylenol, in which 2,6-xylenol is dissolved. It may be in a state or a slurry state. As a specific example, in an aqueous solution containing an anionic surfactant, 2,6-xylenol is oxidized to form 'I' MB.
Examples include a reaction mother port containing unreacted 2,6-xylenol and a water washing solution of T M Th P crystals generated during the TxI production of P.

Examples of the anionic surfactant contained in the aqueous anionic surfactant solution used in the present invention include those in which the hydrophilic moiety is a carboxylate, a sulfonate, a sulfur salt, a phosphate, and the like.

Preferably, the hydrophilic group moiety is a sulfonate and T? i
It is an acid salt, and the examples include alkyl sodium sulfate, sodium alkanesulfonate, and sodium alkylbenzenesulfonate. The content of the anionic surfactant is arbitrary, and usually it is only necessary to contain a very small amount of 6.

The 7' alkali metal salt used in the present invention includes basic,
It can be neutral or acidic, including halides, hydrogen sulfates, sulfates, nitrates, phosphates, carbonates,
Examples include hydrogen carbonate, carboxylate, galate, boroPi salt, and aluminate. Preferably, halides, sulfates, phosphates, carbonates, hydrogen carbonates, borates, etc. are used, and specific examples include sodium chloride, H
sodium phosphate, sodium carbonate, sodium bicarbonate, sodium borate, potassium chloride,
Examples include potassium sulfate, potassium carbonate, and potassium hydrogen carbonate. The amount of the alkali metal salt used is usually 0.0005 to 0.3 times the weight of the anionic surfactant aqueous solution containing 2.6-xylenol, preferably 0.3 times the weight of the anionic surfactant solution containing 2.6-xylenol. It's double. Regarding the method of adding the alkali metal salt, it may be added after the alcohol is added to the surfactant aqueous solution, or it may be added to the surfactant aqueous solution in advance.

The alcohol used as an extraction solvent in the present invention has 4 carbon atoms.
to 12 saturated or unsaturated alcohols. Examples of such alcohols include butanol, isobutanol, sec-butanol, tert-butanol, crotyl alcohol, pentanol, hexanol, 4-methyl-
Examples include 2=pentanol, cyclohexanol, heptatool, octatool, 2-octatool, 2-ethylhexanol, nonanol, decanol, and the like. Preferably butanol, isobutanol, pentanol,
Examples include hexanol, heptatool, and 2-ethylhexanol. The use of alcohol is F and E, but considering the case where 2,6-xylenol is extracted after extraction, a small range is better, and usually 0. 05 to 5 times the weight.

The extraction and recovery of the present invention can be easily carried out by normal operations. For example, a predetermined amount of alcohol is added to a 2,6-xylenol-containing aqueous anionic surfactant solution in which a predetermined amount of an alkali metal salt is dissolved in advance. If the mixture is left to stand after sufficient stirring, it will become emulsified, an interface will quickly appear, and a separated layer will form. By removing a portion of the upper alcohol layer, most of the 2.6-4 silenol can be obtained as an alcohol solution. Although some 2,6-xylenol remains in the raffinate aqueous layer, the extraction is repeated further if necessary. In that case, since most of the anionic surfactant is extracted into the organic layer in the first extraction with alcohol, it is possible to use an organic solvent other than alcohol in the second extraction. In addition, when extracting 2.6 xylenol, if impurities are not a problem, it is sufficient to simply distill off the alcohol and concentrate it. 2.
6-xylenol can be obtained.

<Example> Hereinafter, the present invention will be explained in more detail with reference to Examples.

Testing the state of separation Before actually performing extraction and recovery, two tests were conducted under various conditions.
．． An aqueous anionic surfactant solution containing 6-xylenol and an organic solvent were mixed and the state of layer separation was observed.

2,6--'rSilenol 500+t[r and 33.4 ml of sodium dodecyl sulfate were dissolved in 150 ml of water to prepare a model aqueous solution. Take 5.0ml of this model aqueous solution, add 40 to 80+ ur of inorganic salt and 5.0 ml of organic solvent.
ml was added, mixed by vigorous shaking, and left to stand for 10 minutes, and then the quality of separation at the interface between the organic layer and the aqueous layer was determined.

The results are shown in the table below. When an alkali metal salt was added to the model solution and an alcohol solvent was added, the layer separation state was good. In addition, when each layer was analyzed by It PLC, only a trace amount of 2,6-xylenol was present in the aqueous layer, and most of it was distributed in the alcohol layer.

Example 1 2.6-xylenol (91.6 g < 750 mmol),
Sodium hydrogen carbonate 5.07+r (60.0 mmol)
, li! 24 g (169 mmol) of sodium chloride,
A mixture of 6.2 μm (0,031 mmol) of copper acetate hydrate, 0.46 g (0.46 g <1.60 mmol) of sodium dodecyl sulfate) and 450 ml of water was heated under air pressure (4-9 The reaction was carried out by blowing air at (kf/-).

After cooling to room temperature, add Imbutanol 146+ for extraction.
r and stirred for 5 minutes. The TMBP slurry was filtered and dried to obtain a lemon colored powder.

On the other hand, the r liquid is quickly divided into I-Si due to the synergistic effect of sodium salts and isobutanol, and unreacted 2,6-xylenol is contained in 161 g of isobutanol layer.
0.05+r was distributed in 475 g of aqueous layer, and most of the 2.6--1r silenol in the reaction mother liquor was extracted into inbutanol (extraction recovery rate 99%).

Furthermore, when azeotropic distillation was carried out to recover the imbutanol slightly dissolved in the aqueous layer of the raffinate, there was no foaming at all and the distillation operation was easy.

Example 2 2.6-xylenol 31.06+r (254 mmol), sodium bicarbonate 1.7 g (20 mmol), sodium sulfate 8/Ig (59 mmol), 1 to 2 lithium chloride. Qg (50 mmol), copper acetate (■)-hydrate 2.7 ■ (0.01·1 mmol), sodium dodecyl sulfate 0.17 g (0.59 mmol) and water 143
The reaction was carried out by bubbling oxygen gas into the ml mixture at about 80°C for 13 hours. After cooling to room temperature, 'r
'Filter the M I3 P slurry and wash with water to remove 70g
Washed with inbutanol (28g x 2 times)
After that, it was dried to obtain a lemon-colored powder. The reaction mother liquor containing the catalyst and the like obtained through the filtration was reused for the next reaction.

On the other hand, 1.27 g of unreacted 2,6-xylenol (10,
After shaking, 133.0 g of the washing solution containing 4 mmol) and containing residual sodium salts and surfactants was combined with 56.0 g of the inbutanol washing solution (containing 1.50 g of 2,6-xylenol). When left to stand still, the layers quickly separated, and 26-xylenol was added to the inbutanol layer.
2.70 g in 66f, 0.07 in 141.5 g of water layer
g was distributed, and most of the 2,6-xylenol in the washing solution was extracted into isobutanol (extraction recovery rate 94%).
.

Furthermore, when the aqueous layer of the raffinate was similarly extracted with 397 g of inbutanol, 0.07 g of 2.6 xylenol was extracted in 47.6 g of the inbutanol layer, and traces of 2.6 xylenol were extracted in 133.7 tr of the aqueous layer. (0.01 g or less) (total extraction recovery rate 100%).

The isobutanol extracts were combined, concentrated, and then distilled under reduced pressure to obtain 2.50 g of 2.6-xylenol (70-b, yield 90%).

Bisame Example 1 When toluene was added to the unreacted 2,6-xylenol-containing washing solution from Example 2, shaken, and left to stand, the emulsion was intense and the layers could not be separated cleanly, making it impossible to separate the layers and make the extraction operation impossible. Met.

<Effects of the Invention> According to the present invention, 2.6
When recovering 4r silenol, 2.
Since 6-ff silenol can be efficiently extracted, most of the 2,6-xylenol, which is a problem in terms of pollution control, can be separated from water, greatly reducing wastewater treatment problems, and reducing steam consumption. Since the method of the invention is an extraction method, it is easy and quick to operate, is efficient, and is advantageous for the industry. Sara G-ko, 2
．． 6-='? Since silenol can be obtained as an alni-1-/alni solution, it is easy to simply 2.6-='r-silenol.

Claims (1)

[Claims] A method for recovering 2,6-xylenol, which comprises extracting a 2,6-xylenol-containing anionic surfactant aqueous solution using a saturated or unsaturated alcohol having 4 to 12 carbon atoms in the coexistence of an alkali metal salt. .