JPH07206752A - Purification of diphenyl ether - Google Patents

Abstract

PURPOSE:To provide a purification process for diphenyl ether in which protonic contaminants such as phenol, alkylphenols or the like difficult to be removed by conventional techniques can be readily excluded. CONSTITUTION:The purification process for diphenyl ethers is characterized by contact of crude diphenyl ether with isocyanate followed by distillation for separation.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for purifying diphenyl ethers (hereinafter abbreviated as DPEs). More specifically, the commercially available DPEs are mixed and contacted with the isocyanates, and further separated by distillation to substantially completely remove the protic impurities present in the DPEs.
The present invention relates to a method for purifying PEs.

[0002]

2. Description of the Related Art DPEs, for example, are used as a solvent, a fragrance, and a heat medium, and the production method thereof is mainly obtained by reacting benzene bromide with sodium carbonate in a heated and pressurized state. However, in commercially available DPE, protic compounds such as phenol and alkylphenols as shown in FIG.
pm included. Therefore, when DPE is used as a solvent in a reaction using a compound that reacts immediately with a protic compound as a raw material, satisfactory results may not be obtained.

For example, when DPE which is usually commercially available is used as a polymerization solvent for the polyamidation reaction of isocyanates and carboxylic acids or the self-polyesterification reaction of alcohol groups and carboxylic acid groups of hydroxycarboxylic acids, those functional groups are used. Since the group reacts with the protic impurities in the DPE and acts as an end terminating agent of the polymer, it may not be possible to stably obtain a polymer having a desired high degree of polymerization.

[0004]

Therefore, it is necessary to remove the protic impurities contained in DPE as much as possible, but a purification method for efficiently and substantially completely removing these impurities has been known so far. Absent. In fact, for example D
It may be possible to further subject PE to a rectification step, in which case a precise multi-stage rectification column is required, and unless a rectification with a high reflux ratio is carried out, these trace contents are substantially completely removed. Was difficult to separate. Furthermore, mineral acids such as sulfuric acid, phosphoric acid and nitric acid, and NaOH, KOH, Ca
After adding an alkali such as (OH) ₂ , distillation did not show much effect, and even when purification using an adsorbent such as commonly used activated carbon, zeolite, activated clay, and silica gel was tried. However, these impurities could not be adsorbed selectively and no effect was observed.

As described above, it has been found that industrially complete removal of protic impurities such as phenol and alkylphenols from DPE requires a great deal of labor and cost. Therefore, how to remove these protic impurities from DPE. It was an important issue to remove it easily and practically completely.

[0006]

Means for Solving the Problems The present inventors have paid attention to the fact that protic impurities such as phenol and alkylphenols easily react with an isocyanate group, and as a result of diligent studies, as a result, these impurities were removed from DPEs. The present invention has been achieved by succeeding in removing substantially completely.

That is, the present invention is characterized in that DPEs are contacted with isocyanates and then separated by distillation.
This is a method for purifying PEs.

The isocyanates used in the present invention are not particularly limited, and any isocyanate can be used as long as it can be separated by distillation after contacting with DPEs. For example, as isocyanates that can be used, methylene diisocyanate, ethylene diisocyanate,
Trimethylene diisocyanate, 1-ethylethyl diisocyanate, tetramethylene diisocyanate, pentamethylene diisocyanate, 2-methylbutane-1,
4-diisocyanate, hexamethylene diisocyanate, heptamethylene diisocyanate, 2,2'-dimethylpentane-1,5-diisocyanate, 2,5-dimethylhexane-1,6-diisocyanate, 2 , 2,
4-trimethylpentane-1,5-diisocyanate,
Octamethylene diisocyanate, nonamethylene diisocyanate, 2,2,4-trimethylhexane diisocyanate, decamethylene diisocyanate, undecamethylene diisocyanate, dodecamethylene diisocyanate, tridecamethylene diisocyanate, tetradeca Aliphatic isocyanates such as methylene diisocyanate, pentadecamethylene diisocyanate, hexadecamethylene diisocyanate, cyclopropane-1,2-diisocyanate, cyclopropane-1,2-bis (carbonylisocyanato), Cyclobutane-1,2-bis (methylisocyanato), cyclohexane-1,2-diisocyanate, cyclohexane-1,3-diisocyanate, cyclohexane-1,4-diisocyanate, 1-
Methylcyclohexane-2,4-diisocyanate, 1
-Ethylcyclohexane-2,4-diisocyanate,
4,5-Dimethylcyclohexane-1,3-diisocyanate, 1,2-dimethylcyclohexane-ω, ω'-
Diisocyanate, 1,4-dimethylcyclohexane-
ω, ω′-diisocyanate, isophorone diisocyanate, 1,3,5-trimethyl-2-propylcyclohexane-1ω, 2ω-diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, dicyclohexylmethylmethane -4,4'-diisocyanate, dicyclohexyldimethylmethane-4,4'-diisocyanate, 2,2'-dimethyldicyclohexylmethane-
4,4'-diisocyanate, 3,3'-dimethyldicyclohexylmethane-4,4'-diisocyanate,
3,3′-5,5′-tetramethyldicyclohexylmethane-4,4′-diisocyanate, 2,5-isocyanatomethyltetrahydrofuran, 2,2-isocyanatomethyltetrahydrofuran-5,5′-ether, 2 ，
2,4,4-tetramethyl-1,3-cyclobutane diisocyanate, 2,2,4,4-tetraethyl-1,3
-Cyclobutane diisocyanate, 2,4-diethyl-
2,4-dimethyl-1,3-cyclobutane diisocyanate, 2,4-dimethyl-2,4-dipropyl-1,3
-Cyclobutane diisocyanate, 2,2-dibutyl-
2,4-diethyl-1,3-cyclobutane diisocyanate, 2,4-diethyl-2,4-dimethyl-1,3-
Cyclobutane diisocyanate, 2,4-diethyl-
2,4-Dioctyl-1,3-cyclobutane isocyanate, 2,4-dimethyl-2,4-dipropyl-1,3
-Cyclobutane diisocyanate, 2,4-didecyl-
1,3-cyclobutane diisocyanate, 2- (γ-isocyanatopropyl) cyclohexyl isocyanate,
Alicyclic isocyanate such as 5-dimethyl-1,3-cyclohexylene diisocyanate, dimethyl sulfone diisocyanate, thiodiethyl diisocyanate, thiodipropyl diisocyanate, thiodihexyl diisocyanate, 3,3′- Dinitropentane-1,5-diisocyanate, 3-nitraza-1,5-pentane diisocyanate, 3,6-dinitraza-1,8-octane diisocyanate, 2-nitraza-1,4-butane diisocyanate Nato, 3,10-nitraza-1,12-dodecane diisocyanate, 3,7-dinitraza-1,9-nonane diisocyanate, 3,6,9-trinitraza-1,
Sulfur / nitrogen-containing aliphatic diisocyanates such as 11-undecane diisocyanate and 2,5-dinitraza-1,6-hexane diisocyanate, 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate ,
1,4-diethylbenzol-ω, ω'-diisocyanate, m-phenylenebis (isopropylisocyanato), p-phenylenebis (isopropylisocyanato), 1,3-diphenylpropane-1,3-diisocyanate , 1,4-dimethylnaphthalene-ω, ω'-diisocyanate, 1,5-dimethylnaphthalene-ω, ω
′ -Diisocyanate, anthracene-9,10-bismethylisocyanate, bis (2-isocyanatoethyl) terephthalate, bis (2-isocyanatoethyl)
-P-phenylene diacetate, diphenyl ether-
4,4'-bismethylisocyanate, 4,4'-n-
Propylbiphenyl-ω, ω'-diisocyanate, bis (2-isocyanatoethyl) isophthalate, bis (2-isocyanatoethyl) -p-phenylenediacetate and other aliphatic diisocyanates having an aromatic ring, Methyl ether-ω, ω′-diisocyanate, ethylene glycol diethyl ether-1,1′-diisocyanate, dipropyl ether-ω, ω′-diisocyanate, 3-methoxyhexamethylene diisocyanate, 3
-Butoxyhexamethylene diisocyanate, propylene glycol dipropyl ether-ω, ω'-diisocyanate, dipropylene glycol dipropyl ether-ω, ω'-diisocyanate, carboxyethane-
1,2-diisocyanate, carboxypropane-1,
3-diisocyanate, carboxybutane-1,4-diisocyanate, di- (2-isocyanatocarboxyether) ether, 2,2- (4-isocyanatocarboxyphenyl) propane, 1,11-diisocyanato-
6-acetoxyundecane, 1,11-diisocyanatoundecane-6-one, bis (2-isocyanatoethyl) carbonate, bis (4-isocyanatoethyl) carbonate, lysine diisocyanate, diethyl fumarate-ω, ω ′ -Diisocyanate, diethyl succinate-
ω, ω'-diisocyanate, diethyl adipate-
ω, ω'-diisocyanate and other aliphatic diisocyanates containing oxygen in the main chain, biphenyl-2,4-diisocyanate, biphenyl-4,4'-diisocyanate,
3,3'-Dimethylbiphenyl-4,4'-diisocyanate, 3,3'-Dimethoxybiphenyl-4,4'-
Diisocyanate, 2-nitrobiphenyl-4,4'-
Diisocyanates derived from biphenyl compounds such as diisocyanate, diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 3, 3'-dichlorodiphenylmethane-4,4 '
-Diisocyanate, 3,5-dimethyldiphenylmethane-4,4'-diisocyanate, 2,2'-dimethyldiphenylmethane-4,4'-diisocyanate, 3,
3'-dimethyldiphenylmethane-4,4'-diisocyanate, 3-methoxydiphenylmethane-4,4'-
Diisocyanate, 2,4,6-trimethyldiphenylmethane-3,4'-diisocyanate, 2,2 ', 5
5'-tetramethyldiphenylmethane-4,4'-diisocyanate, 3,3'-dimethoxydiphenylmethane-4,4'-diisocyanate, 4,4'-dimethoxydiphenylmethane-3,3'-diisocyanate, 4,
4'-diethoxydiphenylmethane-3,3'-diisocyanate, 2,2'-dimethyl-5,5'-dimethoxyphenylmethane-4,4'-diisocyanate, 3,
3 ', 5,5'-tetraisopropyldiphenylmethane-4,4'-diisocyanate, bis (4-isocyanatophenyl) dimethylmethane, bis (3-chloro-4-)
Isocyanatophenyl) dimethylmethane, bis (4-isocyanatophenyl) ditrifluoromethylmethane, bis (4-isocyanatophenyl) -2-nitrophenylmethane, bis (4-isocyanatophenyl) -4-nitrophenylmethane, Bis (4-isocyanato-2,5-
Dimethylphenyl) phenylmethane, bis (4-isocyanatophenyl) ethylene, bis (4-isocyanatophenyl) difluoroethylene, bis (4-isocyanatophenyl) cyclohexylmethane, bibenzyl-4,
Diisocyanates derived from diphenyl such as 4'-diisocyanate and bibenzyl-2,4'-diisocyanate, naphthalene-1,5-diisocyanate, 1-
Methylnaphthalene-1,5-diisocyanate, naphthalene-2,6-diisocyanate, naphthalene-2,7
-Diisocyanate, 1,1'-dinaphthyl-2,
2'-diisocyanate, other diphenyl ether-4,4'-diisocyanate, diphenyl sulfide-4,4'-diisocyanate, 1,8-dichlorocarbazole-3,6-diisocyanate, diphenoxy silicon Diisocyanate, tributyl antimony diisocyanate, triisobutyl antimony diisocyanate, phenyl phosphorus diisocyanate, benzyl phosphorus oxide diisocyanate, phenyl phosphorus oxide diisocyanate, 1-methylbenzol-2,4,6-triisocyanate , 1,3,5-trimethylbenzol-2,4,6-triisocyanate, biphenyl-2,
Di and triisocyanates such as 4,4′-triisocyanate and methyldiphenylmethane-4,6,4′-triisocyanate can be mentioned.

Among these, diphenylmethane-4,4'-diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 1,4-, which is relatively inexpensive, easily available and industrially easy to handle, Dimethylcyclohexane-ω, ω′-diisocyanate,
Tolylene-2,4-diisocyanate is preferably used. These isocyanates may be used alone or in combination of two or more.

The DPEs referred to in the present invention include 4,4 '
-Alkyl-substituted diphenyl ether such as dimethyl diphenyl ether, 3,3'-dimethyl diphenyl ether, 3-methyl diphenyl ether, 4,4'-dibromodiphenyl ether, 4,4'-dichlorodiphenyl ether, 4-bromodiphenyl ether, 4-
Halogen-substituted diphenyl ether such as methyl-4'-bromodiphenyl ether, 4-methoxydiphenyl ether, 4,4'-dimethoxydiphenyl ether, 4
Examples thereof include alkoxy-substituted diphenyl ethers such as -methyl-4'-methoxydiphenyl ether and cyclic diphenyl ethers such as dibenzofuran and xanthene.

In the method of the present invention, the above-mentioned isocyanates are mixed and brought into contact with diphenyl ethers to react the protic impurities in the diphenyl ethers with the isocyanates, and then the diphenyl ethers are mixed with the mixture. It is achieved by separating by distillation.

The amount of the isocyanates added is DPE
It is determined by the amount of protic impurities contained in the class. In addition to phenol, phenylphenol, etc., water is also contained in these impurities, but water can be easily removed by bubbling nitrogen under heating. By performing this operation, water is not actually considered. May be. The amount of protic impurities in DPEs other than water is estimated to be about 100 to 300 ppm. Therefore, the addition amount of isocyanates is preferably 0.01 to 5% with respect to DPEs, and preferably, 0.1-2% is good. If the amount is less than 0.01%, the impurities may remain unreacted, and if the amount is more than 5%, the subsequent distillation separation may be difficult.

Regarding the addition temperature and time, since the reactivity of the isocyanate group to phenol and the like is good, it is carried out at the melting point of the solvent to 250 ° C. for 0.1 to 5 hours. In view of the above, it is preferably 50 to 200 ° C. and 0.5 to 2 hours.

The distillation separation operation performed after the treatment can be carried out under atmospheric pressure or reduced pressure, and the distillation method may be any of a thin film distillation method, a simple distillation method and a precision distillation method, without any limitation. Distillation conditions are determined depending on the solvent used under normal pressure and reduced pressure. For example, when diphenyl ether is distilled under reduced pressure, it is 3 to 35 mmHg, 90 to
It can be carried out under the condition of 150 ° C., but is not necessarily limited thereto.

[0015]

[Examples] Examples are shown below. The content of impurities in the DPEs used in Examples and Reference Examples was measured by the following method.

* Phenol and alkylphenols were analyzed and measured using high performance liquid chromatography. Analytical conditions: column; Shim Pack CLC-ODS (M)
(Manufactured by Shimadzu Corporation) Temperature: Room temperature Flow rate: 1 ml / min Mobile phase: Acetonitrile / 0.1 mol-phosphoric acid aqueous solution = 7/3 Detector: uv detector (225 nm)

Example 1 Stirrer. Into a 2 liter reactor equipped with a thermometer, a condenser, a dropping funnel, and a nitrogen introduction tube was charged 1.5 kg of commercially available diphenyl ether (the total content of phenol and alkylphenols was 280 ppm), and nitrogen gas was passed while stirring. After heating to 130 ° C. and bubbling for 2 hours, diphenylmethane-4,4′-diisocyanate 1 was added.
5 g (1% by weight) was added dropwise with a dropping funnel over 10 minutes. After stirring for 1 hour after dropping, the pressure was reduced to 15 mmHg,
Single distillation was carried out at 130 ° C. to distill diphenyl ether to obtain 1.41 Kg (yield 94.0%) of purified diphenyl ether. The content of phenol and alkylphenols in the obtained diphenyl ether was below the detection limit (1 ppm or less). The HPLC analysis chart before and after the treatment is shown in FIG.

Example 2 The procedure of Example 1 was repeated except that 2,4-tolylene diisocyanate was used in place of diphenylmethane-4,4'-diisocyanate, resulting in 1.43 g of purified diphenyl ether. A yield of 95.3% was obtained. The content of phenol and alkylphenols in the obtained diphenyl ether was below the detection limit (1 ppm or less).

In order to show the usefulness of the method of the present invention, polymer synthesis examples will be described below as reference examples. The physical properties of the obtained polymer were measured by the following methods.

* Logarithmic viscosity (ηinh) The logarithmic viscosity (ηinh) is ηinh = ln (t / t.) / Ct. = Flow-down time of solvent in viscometer t = Flow-down time of polymer-dilute solution of same solvent in same viscometer c = Concentration of polymer solids in 100 ml of solvent expressed in grams, polymer solids of polymerization liquid The amount was calculated from the charged amounts of the monomer and solvent, diluted with chloroform to a concentration of 0.1 g polymer solid content / 100 ml, and measured at a temperature of 20 ° C.

Weight average molecular weight (Mw) It was determined by gel permeation chromatography (column temperature 40 ° C.) in comparison with a polystyrene standard sample.

Reference Example 1 In a 500 ml reactor equipped with a stirrer, a thermometer, a condenser, a dropping funnel, and a nitrogen introducing tube, 225 g of diphenyl ether obtained in Example 1 and 83.5% of 90% lactic acid were added.
After g was charged and dehydrated at 130 ° C./100 to 30 mmHg / 8 hours, a molecular sieves tower was attached to the reaction kettle, 0.4 g of tin powder was further charged, and the mixture was heated and refluxed for 30 hours. During the reaction, refluxing diphenyl ether was passed through the molecular sieves tower and returned to the reaction vessel.
After the completion of the reaction, the mixture was cooled to 50 ° C., the obtained polymer slurry liquid was filtered, washed with methanol, and then dried to obtain 54.7 g of a white powdery solid. Yield 91.0
%, Logarithmic viscosity 2.20 dl / g, weight average molecular weight (M
w) was 330000.

Reference Comparative Example 1 Polymerization was performed in the same manner as in Reference Example 1 except that the commercially available diphenyl ether used as the raw material in Example 1 was used, and 53.5 g of a white powdery solid was obtained. Yield 89.0%, logarithmic viscosity 1.24 dl / g, weight average molecular weight (Mw) is 17.0.
It was good.

[0024]

EFFECTS OF THE INVENTION Although it is difficult to purify a trace amount of protic impurities such as phenol and phenylphenol contained in diphenyl ethers to the extent that they are not substantially contained, it can be easily achieved by the method of the present invention. Substantially high-purity diphenyl ethers can be obtained.

[Brief description of drawings]

FIG. 1 is a chart of high performance liquid chromatography of commercially available DPE and DPE treated with the purification method of the present invention.

Claims (2)

[Claims] 1. A method for purifying diphenyl ethers, which comprises contacting diphenyl ethers with isocyanates and then performing distillation separation. 2. The method according to claim 1, wherein the isocyanates are diphenylmethane-4,4′-diisocyanate, xylylenediisocyanate and tolylene-2,4-diisocyanate.