JPH10182517A - New crystal of bisaryl iodonium salt and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a crystal of bis(4-t-butylphenyl)iodonium hexafluorophosphate having excellent storage stability and provide a process for producing the crystal. SOLUTION: This crystal of bis(4-t-butylphenyl)iodonium hexafluorophosphate is characterized by the X-ray diffraction pattern showing characteristic peaks at diffraction angles (2θ) of 6.1 deg., 9.5 deg., 16.4 deg., 17.2 deg. and 18.5 deg. by X-ray diffraction analysis with Cu-Kα ray. The crystal can be produced e.g. by removing methanol from a methanol solution of the compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel crystal of bis (4-t-butylphenyl) iodonium hexafluorophosphate useful as a polymerization initiator and a method for producing the same.

[0002]

2. Description of the Related Art Bis (4-t-butylphenyl) iodonium hexafluorophosphate is used as a polymerization initiator in producing plate-making materials, photoresists, UV-curable inks, photocurable paints, and photosensitive adhesives. ing.

For the preparation of bis (4-tert-butylphenyl) iodonium hexafluorophosphate, see Example 4, US Pat. No. 4,151,175, column 5, column 5.
The reaction was carried out by adding sulfuric acid to a mixture of t-butylbenzene and potassium iodate in methylene chloride at 0 ° C. to obtain a methylene chloride solution of bis (4-t-butylphenyl) iodonium hexafluorophosphate. It is stated that after distilling off the methylene, the remaining solid is pulverized in ethyl ether and dried under reduced pressure to obtain crystals. The crystal produced by this method shows characteristic peaks at diffraction angles (2θ) of 6.0 ° and 18.7 ° in the X-ray diffraction method using Cu-Kα ray (hereinafter, this known crystal is referred to as α). Type crystals). The melting point of this crystal is 171-174 ° C.
Met.

Further, Macromolecules, 10 , 1307-1315 (19)
77), page 23, right column, lines 23-57, the bis (4-t-
Crystals formed by adding an aqueous solution of potassium hexafluorophosphate to an aqueous dispersion of (butylphenyl) iodonium hydrogen sulfate are obtained. The melting point of this crystal is 17
3 to 174 ° C. (1308 page, Table 1). This crystal is also the same α-type crystal as described above.

[0005] Since this α-form crystal modification is inferior in storage stability, its performance as a polymerization initiator is reduced after long-term storage.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a stable and novel crystal of bis (4-t-butylphenyl) iodonium hexafluorophosphate useful as a polymerization initiator and a method for producing the crystal. Is to do.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, bis (4-t-butylphenyl) iodonium hexafluorophosphate has a novel crystal with high stability. However, they have found that this crystal can be obtained by performing a treatment different from a known production method, and have completed the present invention.

That is, the present invention firstly provides a diffraction angle (2θ) of 6.1 ° and 9.5 in the X-ray diffraction method using Cu-Kα ray.
Bis (4-characterized by an X-ray diffraction pattern showing characteristic peaks at °, 16.4 °, 17.2 °, and 18.5 °.
(t-butylphenyl) iodonium hexafluorophosphate crystals. Second, the present invention relates to a bis (4-
The present invention relates to a method for producing crystals of bis (4-t-butylphenyl) iodonium hexafluorophosphate, which comprises precipitating crystals from a methanol solution of t-butylphenyl) iodonium hexafluorophosphate. Thirdly, the present invention is characterized in that a bis (4-t-butylphenyl) iodonium hexafluorophosphate dispersion in a hydrocarbon solvent is subjected to heat treatment, wherein the bis (4-t-butylphenyl) iodonium hexafluorophosphate is heated. And a method for producing the crystal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below.

The novel crystal of the present invention (hereinafter referred to as β-type crystal) shows a characteristic peak at the diffraction angle in the X-ray diffraction method using Cu-Kα ray.
An error of about 0.2 ° is acceptable. The β-type crystal of the present invention has a melting point in the range of 180 to 186 ° C.

According to the first production method of the present invention, β-form crystals are obtained by, for example, distilling off methanol from a methanol solution of bis (4-t-butylphenyl) iodonium hexafluorophosphate to precipitate crystals. can get.

Various forms of bis (4-t-butylphenyl) iodonium hexafluorophosphate may be used to obtain the methanol solution. For example, a crystal form other than the β-form crystal of the present invention, such as the α-form crystal, may be used. Having,
Solvated crystals, amorphous (amorphous), oily substances,
Examples thereof include a mixture of these, and a mixture of these with the β-type crystal of the present invention.

Among them, the α-type crystal can be obtained, for example, by the production method described in the above-mentioned known document. In general, when crystals of bis (4-t-butylphenyl) iodonium hexafluorophosphate are precipitated from a halogenated hydrocarbon solvent such as methylene chloride as described in these known documents, they are usually obtained as α-type crystals. Can be

The solvated crystal is prepared by dissolving bis (4-t-butylphenyl) iodonium hexafluorophosphate in an aromatic hydrocarbon solvent such as toluene or a halogenated hydrocarbon solvent such as dichloroethane. Obtained when precipitated from solution.

The amorphous material is, for example, a screw in a solution state.
It is obtained when (4-t-butylphenyl) iodonium hexafluorophosphate is mixed and precipitated with a non-solvent. When the solvent is distilled off by, for example, concentrating a solution of bis (4-t-butylphenyl) iodonium hexafluorophosphate to remove the solvent, the oily substance may remain without completely removing the solvent and may be formed. .

The heating temperature for dissolving bis (4-t-butylphenyl) iodonium hexafluorophosphate, which can be used as a raw material to obtain a methanol solution, in methanol is preferably 40 to 65 ° C.
5-65C is more preferred. The heating time may be a time required for complete dissolution of the crystal, but is usually preferably 15 minutes to 8 hours, more preferably 30 minutes to 2 hours.

The amount of methanol is preferably 1 to 20 times the weight of bis (4-t-butylphenyl) iodonium hexafluorophosphate to be dissolved.

The methanol can be distilled off from the methanol solution under normal pressure or under reduced pressure. Since the amount of crystals obtained decreases when the residual amount of methanol is large, it is preferable to perform the distillation until almost no methanol is distilled off.

After cooling, the obtained crystals are washed with a small amount of methanol or diethyl ether.
High-purity crystals can be obtained by drying at the following temperature.

According to the second production method of the present invention, the β-form crystal is also produced by heat-treating a hydrocarbon solvent dispersion of bis (4-t-butylphenyl) iodonium hexafluorophosphate. Can be. Bis (4) which can be used to obtain such a hydrocarbon solvent dispersion liquid
As (t-butylphenyl) iodonium hexafluorophosphate, the same ones as those used for preparing the methanol solution in the first production method described above can be used.

Specific examples of the hydrocarbon solvent include n-hexane, n-heptane, n-octane, n-nonane and n-hexane.
Decane, n-undecane, n-dodecane, cyclohexane, methylcyclohexane, decalin and the like can be mentioned, but n-hexane and n-heptane are preferably used.

The heating temperature is preferably from 50 to 80 ° C, more preferably from 60 to 70 ° C. Heat treatment time is 3
0 minutes to 6 hours are preferable, and 1 hour to 2 hours are more preferable.

The amount of the hydrocarbon solvent used for the heat treatment is preferably 1 to 20 times the weight of bis (4-t-butylphenyl) iodonium hexafluorophosphate to be dispersed.

After completion of the heat treatment, β-type crystals can be obtained by cooling, filtering and, if necessary, washing with a small amount of methanol or the like.

[0025]

The present invention will be described more specifically with reference to the following examples.

Reference Example 1 25 g of potassium iodate and 39 g of t-butylbenzene were added to 54 g of acetic anhydride and 153 g of methylene chloride, and the mixture was cooled to 0 ° C. with stirring. To this, 46 g of concentrated sulfuric acid was added dropwise while maintaining the temperature at 0 ° C. or lower. After dropping, keep at 0 ° C for 1.5 hours, then at 20-25 ° C.
Stir for 5 hours. Potassium bisulfate produced by adding 50 g of distilled water was dissolved, and potassium hexafluorophosphate was added.
5 g were added. After stirring for 15 minutes, the methylene chloride layer was separated. Methylene chloride was distilled off by distillation, and 100 ml of ethyl ether was added to the remaining crystals to wash them while crushing large lumps. The finely crushed crystals were separated by filtration and dried under reduced pressure to obtain 32.6 g (yield: 52%) of white crystals. The melting point of the crystals was 171-174 ° C. X of this crystal
The line diffraction diagram is shown in FIG.

Example 1 Acetic anhydride 1 was added to 120 ml of acetic acid.
61.2 g, potassium iodide 64.2 g and t-butylbenzene 96.5 g were added, and the mixture was cooled to 10 ° C. or lower with stirring. 107.8 g of 98% sulfuric acid is maintained at 10 ° C or lower.
Was added dropwise. It took 1 hour to return to room temperature and stirred overnight. The reaction mixture is discharged into 300 g of ice water and unreacted t
-Butylbenzene was extracted and removed with 200 ml of n-hexane. The remaining aqueous layer was diluted by adding 120 ml of water, and 65.8 g of potassium hexafluorophosphate was added little by little. After stirring for 30 minutes, the precipitate was collected by filtration. After drying, the mixture was stirred with 160 ml of methanol at 60 to 65 ° C for 1 hour. From this methanol solution, methanol was distilled off under reduced pressure of 100 to 200 mmHg, and the obtained crystals were washed with 100 ml of diethyl ether and dried to obtain 104.9 g (yield: 65%) of white crystals. The melting point of the crystals was 181 to 183 ° C. FIG. 2 shows an X-ray diffraction pattern of this crystal.

Example 2 The bis (4-t) obtained in Reference Example 1
200 ml of n-heptane was added to 20 g of the α-form crystal of -butylphenyl) iodonium hexafluorophosphate, and the mixture was stirred at 60 to 65 ° C for 1 hour, allowed to cool naturally, and the crystals were collected by filtration. The crystals were dried under reduced pressure for one day to obtain 20 g of white crystals having a melting point of 182 to 184 ° C. FIG. 3 shows an X-ray diffraction pattern of this crystal.

(Example 3) Acetic anhydride 1 was added to 800 ml of acetic acid.
071 g, potassium iodate 428 g and t-butylbenzene 643.2 g were added, and the mixture was cooled to 10 ° C. or lower with stirring. 718 g of 98% sulfuric acid at 10 ° C. or less
Dropped in time. After stirring overnight at 30 ° C. or lower, the reaction mixture was discharged into 2 kg of ice water. After unreacted t-butylbenzene was extracted and removed with 1400 ml of n-heptane, 440 g of potassium hexafluorophosphate was added to the aqueous layer. 3
After stirring for 0 minutes, the precipitate was collected by filtration and washed with 2600 ml of water. To this precipitate, 6650 ml of n-butyl acetate was added and dissolved, and the obtained n-butyl acetate solution was added to 300 ml of water each.
Washed four times with 0 ml each. The oily residue was obtained by collecting n-butyl acetate under reduced pressure of 100 to 200 mmHg until distillation did not occur. 6600 ml of n-heptane was added to this oily substance, and the mixture was stirred at 63 to 65 ° C for 1 hour. The crystals were collected by filtration and dried under reduced pressure for one day to give 663 g of white crystals.
(62% yield). The X-ray diffraction diagram of this crystal shows a diffraction angle (2θ) similar to those obtained in Example 1 and Example 2.
6.1 °, 9.5 °, 16.4 °, 17.2 °, 1
It exhibited a characteristic peak at 8.5 °. The melting point of the crystals was 182 to 184 ° C.

(Evaluation) In order to examine the storage stability of the crystals of bis (4-t-butylphenyl) iodonium hexafluorophosphate obtained in Reference Example 1 and Examples 1 to 3, the performance as a polymerization initiator before and after storage was examined. Was used as a criterion for determination by measuring the polymerization yield when this was used. That is, the higher the polymerization yield, the higher the performance as a polymerization initiator, and A
The value (polymerization yield after storage / polymerization yield before storage) is higher,
This indicates that the storage stability of the crystal is high.

[Storage conditions] 5 g of each crystal was placed in a sample bottle. This was left in a dark place indoors for one year.

[Polymerization conditions] 28.8 g of styrene and 350 mg of bis (4-tert-butylphenyl) iodonium hexafluorophosphate were added to 13 ml of methylene chloride, and UV light was irradiated for 6 minutes using a 450 W high-pressure mercury lamp.

Table 1 shows the polymerization yield and A value of each sample.

[0034]

[Table 1]

[0035]

As is apparent from the value A in Table 1, the β-type crystal of bis (4-t-butylphenyl) iodonium hexafluorophosphate of the present invention has excellent storage stability.

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction diagram of bis (4-t-butylphenyl) iodonium hexafluorophosphate produced in Reference Example 1.

FIG. 2 is an X-ray diffraction diagram of bis (4-t-butylphenyl) iodonium hexafluorophosphate produced in Example 1.

FIG. 3 is an X-ray diffraction diagram of bis (4-t-butylphenyl) iodonium hexafluorophosphate produced in Example 2.

Claims (3)

[Claims] 1. An X-ray diffraction method using Cu-Kα ray, wherein diffraction angles (2θ) are 6.1 °, 9.5 °, 16.4 °, 17.1 °.
A crystal of bis (4-t-butylphenyl) iodonium hexafluorophosphate characterized by an X-ray diffraction pattern showing characteristic peaks at 2 ° and 18.5 °. 2. The crystal of bis (4) according to claim 1, wherein crystals are precipitated from a methanol solution of bis (4-t-butylphenyl) iodonium hexafluorophosphate.
A method for producing a crystal of -t-butylphenyl) iodonium hexafluorophosphate. 3. A bis (4-t-butylphenyl) iodonium hexafluorophosphate dispersion in a hydrocarbon solvent is heat-treated.
A method for producing a crystal of -t-butylphenyl) iodonium hexafluorophosphate.