The invention relates to a cationic photoinitiator which is 4-isobutylphenyl-4apos; preparation method of-methylphenyl iodonium hexafluorophosphate

Abstract

The invention belongs to the technical field of preparation of diaryl iodonium salts, and particularly relates to a preparation method of a cationic photoinitiator 4-isobutylphenyl-4 '-methyl phenyl iodonium hexafluorophosphate, which comprises the following steps: step 1, in the presence of p-toluenesulfonic acid and persulfate, reacting p-iodobenzene with isobutylbenzene; and 2, adding hexafluorophosphate into the reaction solution in the step 1, and carrying out an ion exchange reaction to obtain the 4-isobutylphenyl-4 '-methyl phenyl iodonium hexafluorophosphate. The preparation method has the advantages of mild conditions and simple operation, greatly shortens the process route, avoids the use of acetone and other control reagents, and is suitable for industrial large-scale production. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of diaryl iodonium salt preparation, and specifically relates to a method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyl iodonium hexafluorophosphate. Background Art

[0002] Photoinitiator 250, also known as 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, can be used alone or in combination with appropriate photosensitizers (such as thiazolones) for UV-curable inks, adhesives, paper, metal and plastic surface varnishes; it can also be mixed with α-hydroxyketone initiators to obtain excellent surface curing effects and speeds. Photoinitiator 250 has good applications in graphic arts imaging and adhesives. In dark coatings and inks (such as those containing rutile, titanium dioxide, colored pigments, etc.), only very small concentrations are required to show excellent curing effects, and only very slight yellowing is shown under high-intensity UV radiation. In addition, Photoinitiator 250 has excellent extinction ability and can be used for curing thick film systems when used in combination with appropriate photosensitizers.

[0003] 4-isobutylphenyl-4'-methylphenyl iodonium hexafluorophosphate is an asymmetric aryl iodonium salt. The synthesis methods reported in the literature are mainly the following two:

[0004] 1. p-Iodotoluene is oxidized by ammonium persulfate and then reacted with isobutylbenzene to obtain an intermediate, which is reacted with ammonium chloride to obtain 4-methylphenyl-4'-isobutylphenyl iodonium chloride, which is then ion exchanged with potassium hexafluorophosphate in acetone solvent to obtain the target product (4-methylphenyl)(4-isobutylphenyl)iodonium hexafluorophosphate. The synthetic route is as follows:

[0005]

[0006] 2. p-Iodotole is oxidized with oxyacetic acid to obtain p-iodotoluene diacetate, which is then reacted with p-toluenesulfonic acid to form an activated ester, which is then directly reacted with aromatic hydrocarbons to form iodonium p-toluenesulfonate without separation, and finally ion-exchanged with hexafluorophosphate to obtain the final product of 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate. The synthetic route is as follows:

[0007]

[0008] Method 1 and method 2 have many reaction steps, the reaction products are more complex, the separation and purification are difficult, and the yield is low. Method 2 uses phenylboronic acid compounds, which are relatively expensive, and trifluoromethanesulfonic acid is highly corrosive and has high operating risks. Summary of the invention

[0009] In view of the defects existing in the prior art, the present invention provides a new method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, which has mild conditions and simple operation, greatly shortens the process route, avoids the use of controlled reagents such as acetone, and is suitable for industrial large-scale production.

[0010] Specifically, the present invention provides the following technical solutions:

[0011] A method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, the synthesis route is as follows:

[0012]

[0013] The following steps are involved:

[0014] Step 1: In the presence of p-toluenesulfonic acid and persulfate, p-iodotoluene and isobutylbenzene react;

[0015] Step 2: Add hexafluorophosphate to the reaction solution of step 1 to carry out ion exchange reaction to obtain 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate.

[0016] Preferably, in step 1, the reaction temperature is -10 to 60°C, and the reaction time is 8 to 20 hours.

[0017] Preferably, the persulfate is one or more of sodium persulfate, potassium persulfate and ammonium persulfate.

[0018] Preferably, the hexafluorophosphate is one or more of potassium hexafluorophosphate, sodium hexafluorophosphate and lithium hexafluorophosphate.

[0019] Preferably, the molar ratio of p-iodotoluene to p-toluenesulfonic acid is 1:1 to 1:6, more preferably 1:2 to 1:4.

[0020] Preferably, the molar ratio of p-iodotoluene to persulfate is 1:1 to 1:5, more preferably 1:1 to 1:2.

[0021] Preferably, the molar ratio of p-iodotoluene to isobutylbenzene is 1:0.9 to 1:5, more preferably 1:1 to 1:1.2.

[0022] Preferably, the molar ratio of p-iodotoluene to hexafluorophosphate is 1:0.9 to 1:5, more preferably 1:1 to 1:2.

[0023] Beneficial effects achieved by the present invention:

[0024] (1) The present invention provides a method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate. The entire reaction process can be carried out at -10°C to 60°C, with mild conditions and simple operation.

[0025] (2) The present invention provides a method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, which adopts a one-pot two-step method, omitting the operation of separating and purifying intermediates, greatly shortening the process route, and avoiding the use of controlled reagents such as acetone, and is suitable for industrial large-scale production;

[0026] (3) The present invention provides a method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, and the yield of the product is high, reaching more than 85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate prepared in Example 1 was dissolved in CDCl3. 1 HNMR spectrum.

[0028] Figure 2 This is the HPLC test result of the photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate prepared in Example 4. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is described clearly and completely below. The following embodiments are used to illustrate the present invention, but are not used to limit the scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in the field or the product instructions are used.

[0030] In the following examples, the yield is calculated as follows: amount of final product / amount of p-iodotoluene×100%.

[0031] Example 1

[0032] (1) 15.8 g of p-toluenesulfonic acid, 12.5 g of ammonium persulfate, 10 g of p-iodotoluene and 6.8 g of isobutylbenzene were added to a reaction kettle in sequence and reacted at room temperature for 18 hours;

[0033] (2) Add 8.5 g of potassium hexafluorophosphate to the reaction solution obtained in step (1) and continue the reaction for 10 hours, wash with water and petroleum ether twice respectively, and concentrate to obtain a yellow viscous liquid with a yield of 85.2% and a purity of 99.26%. Figure 1As shown, δ(CDCl3) 0.88 (6H), 1.84 (1H), 2.40 (3H), 2.50 (2H), 7.25 (2H), 7.28 (2H), 7.90 (4H).

[0034] Example 2

[0035] (1) 23.7 g of p-toluenesulfonic acid, 10.5 g of ammonium persulfate, 10 g of p-iodotoluene and 7.4 g of isobutylbenzene were added to a reaction kettle in sequence and reacted at room temperature for 12 hours;

[0036] (2) Add 15.4 g of sodium hexafluorophosphate to the reaction solution obtained in step (1), and continue the reaction for 8 hours. Wash the mixture twice with water and twice with petroleum ether, and concentrate to obtain a yellow viscous liquid with a yield of 85.7% and a purity of 99.24%.

[0037] Example 3

[0038] (1) 31.6 g of p-toluenesulfonic acid, 13 g of potassium persulfate, 10 g of p-iodotoluene and 7 g of isobutylbenzene were added to a reaction kettle in sequence and reacted at room temperature for 8 hours;

[0039] (2) Add 14 g of lithium hexafluorophosphate to the reaction solution obtained in step (1), and continue the reaction for 8 hours. Wash the solution twice with water and twice with petroleum ether, and concentrate the solution to obtain a yellow viscous liquid with a yield of 86.3% and a purity of 99.25%.

[0040] Example 4

[0041] (1) 23.7 g of p-toluenesulfonic acid, 11.5 g of sodium persulfate, 10 g of p-iodotoluene and 7.2 g of isobutylbenzene were added to a reaction kettle in sequence and reacted at room temperature for 20 hours;

[0042] (2) Add 14 g of potassium hexafluorophosphate to the reaction solution obtained in step (1) and continue the reaction for 10 hours, wash twice with water and petroleum ether respectively, and concentrate to obtain a yellow viscous liquid with a yield of 87% and a purity of 99.27%. The liquid phase normalized purity result is as follows: Figure 2 shown.

[0043] Although the present invention has been described in detail above by general description, specific implementation methods and experiments, it is obvious to those skilled in the art that some modifications or improvements can be made to the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all belong to the scope of protection claimed by the present invention.

Claims

1. A method for preparing a cationic photoinitiator 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate, characterized in that: The synthetic route is as follows: The following steps are involved: Step 1: In the presence of p-toluenesulfonic acid and persulfate, p-iodotoluene and isobutylbenzene react; Step 2: Add hexafluorophosphate to the reaction solution of step 1 to carry out ion exchange reaction to obtain 4-isobutylphenyl-4'-methylphenyliodonium hexafluorophosphate.

2. The preparation method according to claim 1, characterized in that: In step 1, the reaction temperature is room temperature and the reaction time is 8-20 hours.

3. The preparation method according to claim 1 or 2, characterized in that: The persulfate is one or more of sodium persulfate, potassium persulfate and ammonium persulfate.

4. The preparation method according to claim 1 or 2, characterized in that: The hexafluorophosphate is one or more of potassium hexafluorophosphate, sodium hexafluorophosphate and lithium hexafluorophosphate.

5. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of p-iodotoluene to p-toluenesulfonic acid is 1:1 to 1:6; The molar ratio of p-iodotoluene to persulfate is 1:1 to 1:5; The molar ratio of p-iodotoluene to isobutylbenzene is 1:0.9 to 1:5; The molar ratio of p-iodotoluene to hexafluorophosphate is 1:0.9 to 1:

5.

6. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of p-iodotoluene to p-toluenesulfonic acid is 1:2 to 1:4; The molar ratio of p-iodotoluene to persulfate is 1:1 to 1:2; The molar ratio of p-iodotoluene to isobutylbenzene is 1:1 to 1:1.2; The molar ratio of p-iodotoluene to hexafluorophosphate is 1:1 to 1:2.

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