CN104817653B - A kind of coumarin oxime ester lightlike initiating agent and preparation method thereof - Google Patents

Abstract

The invention discloses a kind of coumarin oxime ester lightlike initiating agent and preparation method thereof, described light trigger is by the coumarin kind compound containing aldehyde radical and NH₂There is oximation reaction in OH HCl, prepares oxime compound, carry out esterification with acyl chlorides the most again, prepares coumarin oxime ester lightlike initiating agent of the present invention.Light trigger of the present invention can under the enough visible ray of intensity initiated polymerization, there is initiating activity high, the feature that curing rate is fast.

Description

A kind of coumarin oxime ester photoinitiator and preparation method thereof

technical field

The invention relates to the field of photoinitiators, in particular to a photoinitiator containing a coumarin structural unit and an oxime ester group and a preparation method thereof.

Background technique

Environmental and energy issues in today's society are becoming more and more prominent. Photocurable materials are widely accepted and paid attention to as a green, environmentally friendly, and low-energy-consumption environment-friendly material because there is no or only a small amount of solvent volatilization during the curing process.

Photoinitiator is an essential part of photocuring technology, it plays a key role in the photocuring process, determines the speed of photocuring, and even affects the performance of photocuring materials. As an important part of photocuring, the photoinitiator undergoes a photolysis reaction under the excitation of the light source to generate reactive free radicals or ions, and then initiates the polymerization reaction of polymerized monomers or oligomers to form crosslinks. polymer network structure.

Nowadays, photoinitiators are developing rapidly, and a large number of photoinitiator varieties have entered the production process. Among them, oxime ester initiators have received extensive attention due to their superior initiating activity. At present, BASF products OXE-1 and OXE-2 have become highly active photoinitiators occupying a certain market proportion. Domestically, there are also many patents on oxime ester photoinitiators, such as diphenyl sulfide ketoxime ester photoinitiator (CN102492059A), bis-oxime ester photoinitiator (CN103833872A) and the like. However, the excitation wavelength of most initiators is in the ultraviolet region, which cannot match the increasingly common LED light source, and the ultraviolet light will cause damage to the surface of the cured material, which is harmful to the human body. These deficiencies hinder the development of oxime ester initiators. development of.

Therefore, it is of great economic significance to develop oxime ester initiators with high initiating activity and strong response in the visible light region.

Contents of the invention

In view of the above-mentioned problems in the prior art, the applicant provides a coumarin oxime ester photoinitiator and a preparation method thereof. The photoinitiator of the invention can initiate polymerization reaction under visible light with sufficient intensity, and has the characteristics of high initiation activity and fast curing speed.

Technical scheme of the present invention is as follows:

A kind of coumarin oxime ester photoinitiator, described photoinitiator has following molecular structure general formula:

in,

R1 is one of hydrogen atom, C ₁ ~ C ₆ aliphatic hydrocarbon group, C ₁ ~ C ₆ alkoxy group, C ₁ ~ C ₆ dialkylamino group; R2 is C ₁ ~ C ₆ aliphatic hydrocarbon group, benzene One of the groups; the oxime ester group is located at the 3 or 4 position of coumarin.

A preparation method of coumarin oxime ester photoinitiator, comprises the steps:

(1) Under the condition that oxidant selenium dioxide exists, 4-methyl-7-R1 base coumarin is oxidized into intermediate B-1 in organic solvent xylene, and concrete reaction formula is as follows:

Wherein: R1 is one of hydrogen atom, C ₁ -C ₆ aliphatic hydrocarbon group, C ₁ -C ₆ alkoxy group, C ₁ -C ₆ dialkylamino group;

(2) Under weak base catalysis, 4-R1 base salicylaldehyde and diethyl malonate undergo a dehydration condensation reaction to generate an unsaturated carboxyl compound, and then decarboxylation occurs under the catalysis of hydrochloric acid and glacial acetic acid to prepare To obtain intermediate C, the specific reaction formula is as follows:

Wherein: R1 is one of hydrogen atom, C ₁ -C ₆ aliphatic hydrocarbon group, C ₁ -C ₆ alkoxy group, C ₁ -C ₆ dialkylamino group;

(3) Phosphorus oxychloride reacts with dry DMF to generate vilsmiere reagent, and vilsmiere reagent reacts with intermediate C to obtain intermediate B-2. The specific reaction formula is as follows:

Wherein: R1 is one of hydrogen atom, C ₁ -C ₆ aliphatic hydrocarbon group, C ₁ -C ₆ alkoxy group, C ₁ -C ₆ dialkylamino group;

(4) Under the action of catalyst sodium acetate, intermediate B-1 or B-2 and hydroxylamine hydrochloride undergo oximation reaction in ethanol to obtain oxime compound D. The oximation reaction equation is as follows:

Among them: R1 is hydrogen atom, C ₁ ~ C ₆ aliphatic hydrocarbon group, C ₁ ~ C ₆ alkoxy group, C ₁ ~ C ₆ dialkylamine

One of the groups; the oxime group is located at the 3 or 4 position of coumarin;

(5) Using NaH as a catalyst, the oxime compound D and the acid chloride carry out esterification reaction to obtain the oxime ester compound A, that is, the coumarin oxime ester photoinitiator, and the specific reaction formula is as follows:

Among them: R1 is one of hydrogen atom, C ₁ ~ C ₆ aliphatic hydrocarbon group, C ₁ ~ C ₆ alkoxy group, C ₁ ~ C ₆ dialkylamino group; R2 is C ₁ ~ C ₆ aliphatic hydrocarbon group , One of the phenyl groups; the oxime ester group is located at the 3 or 4 position of coumarin.

The temperature of the oxidation reaction in the step (1) is 130-150°C.

Weak base is piperidine in the condensation reaction in described step (2), and the mol ratio of 4-R1 base salicylaldehyde and diethyl malonate is 1:1.3～1.6, and the reaction temperature of described condensation reaction is 75～ 85°C.

The volume ratio of hydrochloric acid and glacial acetic acid in the decarboxylation reaction in the step (2) is 1:1, and the reaction temperature of the decarboxylation reaction is 90-100°C.

In the step (3), the mol ratio of phosphorus trichloride to DMF is 1:1～1.3;

In the step (3), the molar ratio of the vilsmiere reagent to the intermediate C is 1.1-1.5:1, and the reaction temperature of the formaldehyde reaction is 50-70°C.

In the step (4), the molar ratio of intermediate B-1 or B-2 to hydroxylamine hydrochloride is 1:1.1-1.5, and the reaction temperature of the oximation reaction is 70-80°C.

In the step (5), the molar ratio of the oxime compound D to the acid chloride is 1:1.1-1.5, the solvent is tetrahydrofuran, and the reaction temperature of the esterification reaction is 20-30°C.

The beneficial technical effects of the present invention are:

1. The preparation method of the coumarin oxime ester photoinitiator of the present invention is mature, simple and easy to implement, and the purification method of the product is simple, high in purity and high in yield;

2. The coumarin oxime ester photoinitiator of the present invention has high initiating activity in the range of visible light, fast curing speed, and has a good application prospect in visible light polymerization and molding.

Description of drawings

Fig. 1 is the ultraviolet absorption spectrogram of the obtained oxime ester photoinitiator of embodiment 1 of the present invention and embodiment 2;

Wherein, the concentration of the photoinitiator is 5.5×10 ^-5 mol/L (acetonitrile is used as the solvent).

Fig. 2 is the double bond conversion curve of the photosensitive resin containing the oxime ester photoinitiator obtained in Example 2 of the present invention during the light curing process.

detailed description

The present invention will be specifically described below in conjunction with the accompanying drawings and embodiments.

Example 1

The preparation of photoinitiator A1-1, concrete preparation steps are as follows:

(1) In a 250mL three-necked flask with a condenser tube, 4.62g of 4-methyl-7-diethylaminocoumarin and 3.3g of selenium dioxide were dissolved in 120mL of xylene, and the whole system was Under the protection of N , stirred and reacted at 130° C. for ₁₂ h; filtered off the solid residue in the mixture while hot, and spin-dried the solvent to obtain the crude product; the crude product was subjected to silica gel column chromatography (petroleum ether: ethyl acetate=5:1 ) separation and purification to obtain red solid B-1. Yield: 74%.

NMR: ¹ H NMR (400MHz, CDCl ₃ ) δ10.06(s, 1H), 8.33(d, J=9.2Hz, 1H), 6.66(dd, J=9.2, 2.6Hz, 1H), 6.55(d, J=2.6Hz, 1H), 6.48(s, 1H), 3.46(q, J=7.1Hz, 4H), 1.25(t, J=7.1Hz, 6H).

(2) In a 25mL three-neck flask with a condenser, dissolve 0.163g of B-1 and 0.072g of NH ₂ OH·HCl in 10mL of absolute ethanol, and stir under N ₂ protection; 0.082g of Sodium acetate was dissolved in 1mL of water, then added dropwise to the solution, and heated to 75°C for 1 hour; then the solvent was removed by rotary evaporation to obtain a crude product, which was washed with water several times and then rinsed with ethanol, and dried to obtain a red pure product D-1 , the yield was 76%.

NMR: ¹ H NMR (400MHz, DMSO) δ12.37(s, 1H), 8.45(s, 1H), 8.19(d, J=9.1Hz, 1H), 6.75(t, J=22.8Hz, 1H), 6.62 (s, 1H), 6.30 (s, 1H), 3.52 (q, 4H), 1.20 (t, J=6.7Hz, 6H).

(3) In a 50mL single-necked bottle, dissolve 0.26g of D-1 and 0.06g of NaH in 15mL of dehydrated tetrahydrofuran, stir for 30min under the protection of N ₂ and cool down to 0°C, and dissolve 0.15mL of benzyl Acid chloride was added dropwise to the reaction vessel, and the temperature was raised to 20°C; after 20 min, the reaction was quenched with 50 mL of 5% sodium bicarbonate solution, then extracted 4 times with 30 mL of dichloromethane, and then washed with 50 mL of saturated sodium chloride solution. phase, the organic phase was dried with anhydrous sodium sulfate, filtered, and the solvent was removed by rotary evaporation to obtain a red solid powder A1-1. The yield was 17.3%.

NMR: ¹ H NMR (400MHz, DMSO) δ9.12 (s, 1H), 8.26 (d, J = 9.2Hz, 1H), 8.19–8.05 (m, 2H), 7.82–7.75 (m, 1H), 7.64 (t, J=7.7Hz, 2H), 6.81(dd, J=9.2, 2.6Hz, 1H), 6.62(d, J=2.5Hz, 1H), 6.47(s, 1H), 3.47(q, J= 6.9Hz, 4H), 1.15(t, J=7.0Hz, 6H).

Example 2

The preparation of photoinitiator A2-1, concrete preparation steps are as follows:

(1) In a 100mL three-neck flask with a condenser tube, dissolve 1.93g of 4-diethylamino salicylaldehyde, 3.2g of diethyl malonate and 1mL of piperidine in 30mL of absolute ethanol, and Under the protection of N ₂ , stir, and react at 75°C for 6 h; spin dry the ethanol to obtain the intermediate product, add it to a 100 mL three-neck flask with a condenser tube, add 20 mL of concentrated hydrochloric acid and 20 mL of glacial acetic acid to the bottle, and under N ₂ protection, Raise the temperature to 100°C and stir for 6 hours; then cool the mixture to room temperature, pour it into 100mL of ice water, adjust its pH value to about 5 with 40% sodium hydroxide solution, a light yellow solid precipitates, continue to stir for 30 minutes, and then filter to obtain a solid The crude product was washed with water for several times, washed with absolute ethanol for several times, and dried to obtain pure product C with a yield of 86%.

NMR: ¹ H NMR (400MHz, CDCl ₃ ) δ7.55 (d, J = 9.3Hz, 1H), 7.26 (d, J = 8.8Hz, 1H), 6.58 (dd, J = 8.8, 2.1Hz, 1H) , 6.51 (d, J=1.8Hz, 1H), 6.05 (d, J=9.3Hz, 1H), 3.43 (q, J=7.1Hz, 4H), 1.23 (t, J=7.1Hz, 6H).

(2) In a 50mL dry single-necked flask, add 2mL of phosphorus oxychloride, stir under the protection of _N2 , slowly add 2mL of dehydrated DMF into the flask, and stir for 30min; dissolve 1.50g of C into 10mL Add the dehydrated DMF slowly to the one-necked bottle, raise the temperature to 60°C, and pour it into 100mL of ice water after 12 hours; adjust the pH with 20% sodium hydroxide solution until a large amount of solids are precipitated, and filter to obtain yellow The solid crude product was washed with water and washed several times with absolute ethanol to obtain B-2, the yield: 70%.

NMR: ¹ H NMR (400MHz, CDCl ₃ ) δ10.16(s, 1H), 8.28(s, 1H), 7.44(d, J=9.0Hz, 1H), 6.66(dd, J=9.0, 2.0Hz, 1H), 6.52(s, 1H), 3.50(q, J=7.1Hz, 4H), 1.28(t, J=7.1Hz, 6H).

(3) The experimental operation was the same as step (2) in Example 1 to obtain product D-2 with a yield of 74%.

NMR: ¹ H NMR (400MHz, DMSO) δ11.30(s,1H), 8.15(s,1H), 7.99(s,1H), 7.54(d,J＝8.6Hz,1H), 6.73(d,J =8.3Hz, 1H), 6.49(d, J=48.5Hz, 1H), 3.43(t, J=13.8Hz, 4H), 1.36–1.03(m, 6H).

(4) The experimental operation was the same as step (3) in Example 1 to obtain the product A2-1 with a yield of 64%.

NMR: ¹ H NMR (400MHz, CDCl ₃ ) δ8.80(s,1H), 8.53(s,1H), 8.20–8.11(m,2H), 7.73–7.59(m,1H), 7.52(t,J =7.7Hz, 2H), 7.40(d,J=8.9Hz,1H), 6.66(dd,J=8.9,2.5Hz,1H), 6.52(d,J=2.3Hz,1H), 3.48(q,J =7.1Hz, 4H), 1.27(t, J=7.1Hz, 6H).

Test case:

Taking the products in the above examples as examples, performance tests and characterizations were carried out on the oxime ester photoinitiators of the present invention.

1. Characterization of ultraviolet absorption wavelength

Test method: Accurately weigh 0.002g (5.5×10 ^-6 mol) of photoinitiator and place it in a 100mL brown volumetric flask, then add acetonitrile to the bottle to form a solution with a concentration of 5.5×10 ^-5 mol/L, Use a spectrophotometer to carry out the characterization of the ultraviolet absorption wavelength, and the characterization results are shown in Figure 1;

As can be seen from Figure 1, the maximum absorption wavelength of the two oxime ester photoinitiators is around 440nm, which belongs to visible light initiators; and, at the same concentration, the absorption intensity of the photoinitiator obtained in Example 2 is greater, and the photoresponsiveness is stronger.

2. Double bond conversion rate test

The formula of photosensitive resin: resin monomer is trimethylolpropane triacrylate (TMPTA), and embodiment 2 makes photoinitiator A2-1, and photoinitiator addition is 2wt%;

The photosensitive resin was drop-coated on the surface of the KBr salt sheet, the film thickness was controlled at about 0.5mm, the irradiation time was 300s, the light source intensity was controlled at 40mw/cm ² , and the curing process was monitored in real time with a Nicolet 6700FT-IR infrared spectrometer. The test results are shown in Figure 2;

As can be seen from the figure, the photosensitive resin using the oxime ester photoinitiator obtained in Example 2 has the fastest reaction in the first 25s of illumination, and the double bond conversion rate changes greatly, reaching about 45%. After that, the reaction is slow, and the final double bond The conversion rate reaches about 70%.

3. Cured film performance test

The formula of photosensitive resin: resin monomer is trimethylolpropane triacrylate (TMPTA) and pentaerythritol tetra-3-mercapto propionate (weight ratio is 1:1), the photoinitiator A2-1 of embodiment 2 gained, Photoinitiator addition is 2wt%;

The above photosensitive resin was cured under a light source with a wavelength of 405nm to form a film, and the pencil hardness reached 3H.

The above-mentioned example is only to describe the experimental scheme of the preferred example of the present invention, and is not to limit the scope of the present invention. Under the premise of not violating the original intention of the present invention, those skilled in the art can modify and improve the technical scheme of the present invention. All should be within the scope of protection of the claims of the present invention.

Claims (9)

1. A coumarin oxime ester photoinitiator is characterized in that the photoinitiator has the following molecular structure general formula:

wherein,

r1 is hydrogen atom, C₁～C₆Aliphatic hydrocarbon group of (C)₁～C₆Alkoxy group of (C)₁～C₆One of the dialkylamino groups of (a);r2 is C₁～C₆One of the aliphatic hydrocarbon group and the phenyl group; the oxime ester group is located at the 3 or 4 position of coumarin.

2. A process for the preparation of coumarin oxime ester photoinitiators as claimed in claim 1, which comprises the steps of:

(1) oxidizing 4-methyl-7-R1-base coumarin into an intermediate B-1 in an organic solvent xylene in the presence of oxidant selenium dioxide, wherein the specific reaction formula is as follows:

wherein: r1 is hydrogen atom, C₁～C₆Aliphatic hydrocarbon group of (C)₁～C₆Alkoxy group of (C)₁～C₆One of the dialkylamino groups of (a);

(2) under the catalysis of weak base, 4-R1-based salicylaldehyde and diethyl malonate undergo dehydration condensation reaction to generate an unsaturated carboxyl compound, and then undergo decarboxylation reaction under the catalysis of hydrochloric acid and glacial acetic acid to prepare an intermediate C, wherein the specific reaction formula is as follows:

wherein: r1 is hydrogen atom, C₁～C₆Aliphatic hydrocarbon group of (C)₁～C₆Alkoxy group of (C)₁～C₆One of the dialkylamino groups of (a);

(3) reacting phosphorus oxychloride with dried DMF to generate a vilsmiere reagent, and performing a formalization reaction on the vilsmiere reagent and the intermediate C to prepare an intermediate B-2, wherein the specific reaction formula is as follows:

wherein: r1 is hydrogen atom, C₁～C₆Aliphatic hydrocarbon group of (C)₁～C₆Alkoxy group of (C)₁～C₆One of the dialkylamino groups of (a);

(4) under the action of a catalyst sodium acetate, carrying out oximation reaction on the intermediate B-1 or B-2 and hydroxylamine hydrochloride in ethanol to obtain an oxime compound D, wherein the oximation reaction formula is as follows:

wherein: r1 is hydrogen atom, C₁～C₆Aliphatic hydrocarbon group of (C)₁～C₆Alkoxy group of (C)₁～C₆One of the dialkylamino groups of (a); the oxime group is located at the 3 or 4 position of coumarin;

(5) the method comprises the following steps of carrying out esterification reaction on an oxime compound D and acyl chloride by using NaH as a catalyst to obtain an oxime ester compound A, namely the coumarin oxime ester photoinitiator, wherein the specific reaction formula is as follows:

wherein: r1 is hydrogen atom, C₁～C₆Aliphatic hydrocarbon group of (C)₁～C₆Alkoxy group of (C)₁～C₆One of the dialkylamino groups of (a); r2 is C₁～C₆One of the aliphatic hydrocarbon group and the phenyl group; the oxime ester group is located at the 3 or 4 position of coumarin.

3. The method according to claim 2, wherein the temperature of the oxidation reaction in the step (1) is 130 to 150 ℃.

4. The method according to claim 2, wherein the weak base in the condensation reaction in step (2) is piperidine, the molar ratio of 4-R1-ylsalicylaldehyde to diethyl malonate is 1: 1.3-1.6, and the reaction temperature of the condensation reaction is 75-85 ℃.

5. The production method according to claim 2, characterized in that the volume ratio of hydrochloric acid to glacial acetic acid in the decarboxylation reaction in the step (2) is 1:1, and the reaction temperature of the decarboxylation reaction is 90-100 ℃.

6. The preparation method according to claim 2, wherein the molar ratio of phosphorus oxychloride to DMF in the step (3) is 1: 1-1.3.

7. The preparation method according to claim 2, wherein the molar ratio of vilsmiere reagent to intermediate C in the step (3) is 1.1-1.5: 1, and the reaction temperature of the formalization reaction is 50-70 ℃.

8. The method according to claim 2, wherein the molar ratio of the intermediate B-1 or B-2 to hydroxylamine hydrochloride in the step (4) is 1:1.1 to 1.5, and the reaction temperature of the oximation reaction is 70 to 80 ℃.

9. The preparation method according to claim 2, wherein the molar ratio of the oxime compound D to the acid chloride in the step (5) is 1: 1.1-1.5, the solvent is tetrahydrofuran, and the reaction temperature of the esterification reaction is 20-30 ℃.