Compound containing urea structure as well as preparation method and application of compound in color developing agent

Abstract

The invention discloses a compound containing a urea structure as well as a preparation method and application of the compound in a color developing agent, and relates to the technical field of color developing agents. The compound containing the urea structure is a # imgabs0 # structure as shown in a formula 1. The compound containing the urea structure is synthesized through multiple steps of Suzuki reaction, bromination reaction and substitution reaction. The compound is used as an electron donor to be applied to a thermosensitive color development system and forms a color development composition with a phenolic compound and an acidic material, and the activation temperature is as low as 60-120 DEG C. The ureido structure stabilizes a reaction intermediate through a hydrogen bond network, enhances the electron transfer efficiency, and significantly improves the color developing sensitivity; the aryl / heteroaryl substituent optimizes the color contrast through the conjugation effect, and meanwhile, the synergistic effect of the hot-melt filler ensures the stability of the system. Compared with a traditional color developing agent, the color developing agent has the advantages of low-temperature activation, high color developing intensity and excellent weather resistance, is suitable for the fields of thermal printing, anti-counterfeiting materials and the like, and overcomes the defects of high reaction temperature and insufficient stability in the prior art.

Description

Technical Field

[0001] The invention relates to the technical field of color developers, and in particular to a compound containing a urea structure, a preparation method thereof, and application in a color developer. Background Art

[0002] In today's society, color developers play a vital role in many fields, such as thermal printing paper, chemical sensors, anti-counterfeiting materials, etc. Although traditional color developers can basically meet the color development needs, there are many problems that need to be solved. On the one hand, its color development sensitivity is limited, and it is difficult to show clear color changes in complex environments or low concentrations, which affects the detection accuracy and the visual effect of the material; on the other hand, the color development stability is poor and is easily affected by factors such as temperature, humidity, and light, causing the color to gradually fade or shift, shortening the service life of related products.

[0003] Taking the thermosensitive color development system as an example, the currently commonly used color development composition is mainly composed of phenolic compounds, acidic substances and some electron donors. However, when traditional electron donors react with phenolic compounds to develop colors, they are not sufficiently reactive and require higher temperatures to activate the color development process, which not only increases energy consumption but also limits its application in temperature-sensitive scenarios. At the same time, some traditional electron donors have poor compatibility with phenolic compounds and acidic substances, which can easily lead to stratification or precipitation of the color development system, further affecting the uniformity and stability of the color development effect.

[0004] In view of this, the development of new urea-containing compounds for color developers has become a research hotspot and urgent need in this field. With their unique chemical properties, urea-containing compounds are expected to form more stable and sensitive color-developing compositions with phenolic compounds and acidic substances, making up for the defects of traditional color developers, expanding their application range in various industries, and providing key material support for the technological upgrading of related industries. Summary of the invention

[0005] The purpose of the present invention is to provide a urea structure-containing compound with high color development sensitivity, good stability and the ability to activate the color development reaction at a relatively low temperature, as well as a preparation method thereof and the application of the compound in the color development agent in order to solve the problems of low color development sensitivity, poor stability and harsh reaction conditions of the color development agent in the prior art.

[0006] To achieve the above object, the technical solution adopted by the present invention is: a compound containing a urea structure, wherein the compound containing a urea structure is a structure shown in Formula 1: Formula 1; The R 1 Selected from: an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an aryl group having 6 to 15 carbon atoms, and a heteroaryl group having 5 to 10 carbon atoms; or the R 1 is selected from: an aryl group having 6 to 15 carbon atoms substituted with an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms; or the R 1 is selected from: a heteroaryl group having 5 to 10 carbon atoms substituted with an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

[0007] Furthermore, the alkyl group having 1 to 10 carbon atoms is selected from: methyl, ethyl, propyl, tert-butyl.

[0008] Furthermore, the alkoxy group having 1 to 10 carbon atoms is selected from: methoxy, ethoxy.

[0009] Furthermore, the aryl group having 6 to 15 carbon atoms is selected from: phenyl, naphthyl, biphenyl.

[0010] Furthermore, the heteroaryl group having 5 to 10 carbon atoms is selected from: furyl, thienyl.

[0011] Furthermore, the compound containing a urea structure is selected from the compounds shown in the following structures: .

[0012] A method for preparing a compound containing a urea structure, comprising the following steps: ;

[0013] In the first step, intermediate 1 is synthesized by the Suzuki reaction of raw material 1 and raw material 2; In the second step, intermediate 2 is synthesized by the bromination reaction of intermediate 1; In the third step, intermediate 3 is synthesized by the Suzuki reaction of intermediate 2 and raw material 3; In the fourth step, the compound is synthesized by the substitution reaction of intermediate 3 and raw material 4.

[0014] Furthermore, the raw material 4 is selected from the compounds shown in the following structures: , , , , , , , , , , , , , , .

[0015] Application of a compound containing a urea structure in a developer

[0016] Furthermore, the developer is a thermosensitive color-developing system, and the compound containing a urea structure acts as an electron donor and forms a color-developing composition with a phenolic compound and an acidic substance. The mass fraction of the compound containing a urea structure in the color-developing composition is 0.5 - 15 parts, and the activation temperature of the color reaction is 60 - 120 °C.

[0017] Furthermore, the thermosensitive color-developing system comprises the following components in mass fractions: the compound containing a urea structure is 0.5 - 15 parts, the phenolic compound is 20 - 50 parts, the acidic substance is 5 - 30 parts, and the hot-melt filler is 5 - 10 parts.

[0018] Furthermore, the phenolic compound is selected from at least one of bisphenol A, hydroquinone, resorcinol, and 4-hydroxybenzoate.

[0019] Furthermore, the acidic substance is selected from at least one of stearic acid, salicylic acid, p-toluenesulfonic acid, and dodecylbenzenesulfonic acid.

[0020] Furthermore, the hot-melt filler is selected from at least one of paraffin wax, microcrystalline wax, and polyethylene wax.

[0021] Furthermore, the preparation method of the thermosensitive color-developing system is: mixing the compound containing a urea structure, the phenolic compound, the acidic substance, and the hot-melt filler according to the mass fractions, heating the mixture to 50 - 100 °C to melt and stirring evenly, then cooling to room temperature, and grinding to obtain the thermosensitive color-developing system.

[0022] The compound containing a urea structure of the present invention acts as an electron donor and undergoes an electron transfer reaction with a phenolic compound (electron acceptor) under acidic conditions in the thermosensitive color-developing system. The amino group in the urea structure provides an electron-rich environment. After being activated by heat, electrons are transferred from the urea group to the phenolic compound, forming a charge transfer complex, resulting in a change in the conjugated structure and color development. The strong hydrogen-bonding ability of the urea group can form an intermolecular hydrogen-bond network with phenolic hydroxyl groups or acidic substances, stabilizing the reaction intermediate and reducing the activation energy of the reaction, thereby achieving the activation of the color reaction at a lower temperature (60 - 120 °C). The hot-melt filler (such as paraffin wax) melts when heated, promoting the full contact of the urea-containing compound, the phenolic compound, and the acidic substance. The rigid plane of the urea structure and the aromatic ring of the phenolic compound enhance the intermolecular force through π-π stacking, accelerating the color reaction.

[0023] The compound with a urea structure according to the present invention, wherein the two amino groups in the urea group provide high electron density, significantly enhancing the electron transfer efficiency. The urea group binds to phenols and acidic substances through hydrogen bonds, improving the thermal stability of the color development system and preventing component stratification. When it is substituted by alkyl / alkoxy groups, the solubility can be improved to ensure color development uniformity. When it is substituted by aryl / heteroaryl groups, the electron delocalization is extended through the conjugation effect, enhancing the color development contrast; heteroatoms (O, S) can further adjust the electron cloud distribution. The planarity of the urea nucleus promotes the π-π stacking with phenolic compounds, enhancing the molecular pre-organization effect and making the color development reaction faster and more sensitive.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Improvement in color development sensitivity: The compound with a urea structure significantly reduces the activation temperature of the color development reaction by enhancing the electron transfer efficiency, solving the bottleneck of high-temperature activation in traditional technologies.

[0025] 2. Optimization of color development stability and contrast: The hydrogen bond network and conjugated structure design of the urea group improve the stability of the thermosensitive color development system, and at the same time enhance the color development contrast through the molecular pre-organization effect.

[0026] 3. Expansion of application compatibility: Compared with traditional electron donors, the compound with a urea structure according to the present invention shows better solubility and component compatibility in the thermosensitive color development system, and is applicable to more complex or temperature-sensitive scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a preparation method of the compound with a urea structure according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0028] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Example 1

[0029] Synthesis of Compound 1: ; In the first step, 20 g of raw material 1, 15.60 g of raw material 2, 1.69 g of tetrakis(triphenylphosphine)palladium, 13.46 g of anhydrous potassium carbonate and 200 g of a mixed solution of toluene, ethanol and water (volume ratio of 2:1:1) were added to the reaction system in sequence under a nitrogen atmosphere. The reaction system was heated to 75°C and stirred, heated and refluxed for 10 hours. The heating was turned off, cooled to room temperature, and allowed to stand for separation. The aqueous phase was extracted twice with ethyl acetate, the organic phases were combined, washed three times with water, spun dry, and column chromatography was performed, using a mixture of petroleum ether and dichloromethane as an eluent to finally obtain 21.51 g of intermediate 1. MS[MS+1]: 598.

[0030] In the second step, 21.51 g of intermediate 1, 9.61 g of N-bromosuccinimide and 220 g of dichloromethane were added to the reaction system in sequence under a nitrogen atmosphere. The reaction system was stirred at 25 °C for 16 hours. After the reaction was completed, the mixture was filtered and 300 mL of saturated NaHCO 3 The filter was washed with 200 mL of brine and then with anhydrous MgSO 4 After drying and spin drying, column chromatography was performed using a mixture of petroleum ether and dichloromethane as the eluent to finally obtain 16.99 g of intermediate 2. MS [MS+1]: 637.

[0031] In the third step, 16.99 g of intermediate 2, 4.39 g of raw material 3, 0.6 g of tetrakis(triphenylphosphine)palladium, 7.38 g of anhydrous potassium carbonate, and 190 g of a mixed solution of toluene, ethanol, and water (volume ratio 2:1:1) were added to the reaction system in sequence under a nitrogen atmosphere. The reaction system was heated to 75°C and stirred and heated under reflux for 10 hours. The heating was turned off, cooled to room temperature, and allowed to stand for separation. The aqueous phase was extracted twice with ethyl acetate, the organic phases were combined, washed three times with water, spun dry, and column chromatography was performed using a mixture of petroleum ether and dichloromethane as the eluent to finally obtain 14.19 g of intermediate 3. MS[MS+1]: 689.

[0032] In the fourth step, 14.19 g of intermediate 3, 2.83 g of raw material 4, 5.69 g of potassium carbonate, 0.6 g of tris(dibenzylideneacetone)dipalladium, 8.34 g of tri-tert-butylphosphine and 150 g of toluene were added to the reaction system in sequence under a nitrogen atmosphere. The reaction system was heated to 120 ° C, stirred and refluxed for 12 hours. After the reaction was completed, the temperature was slightly lowered and filtered using diatomaceous earth to remove salts and catalysts. After the filtrate was cooled to room temperature, it was washed three times with water and the organic phase was retained. Then, the aqueous phase was extracted with ethyl acetate, and after the organic phase was combined, it was dried with anhydrous magnesium sulfate, spin-dried, and column chromatography was performed with a mixture of petroleum ether and dichloromethane as the eluent to finally obtain 13.05 g of compound 1. MS[MS+1]: 767.

[0033] Of Compound 1 1 HNMR (chloroform-d): δ 8.72 (dd, 1H), 8.19 (s, 1H), 8.12 - 8.07 (m, 1H), 8.04 (s, 1H), 7.76 - 7.60 (m, 6H), 7.60 - 7.44 (m, 7H), 7.34 - 7.26 (m, 3H), 6.91 - 6.83 (m, 2H), 6.58 (dd, 1H), 4.19 (t, 2H), 3.93 (s, 3H), 3.83 (s, 3H), 2.93 (s, 3H), 1.82 - 1.71 (m, 2H), 1.39 (h, 2H), 0.92 (t, 3H).

[0034] Examples 2 - 6 For the compounds synthesized in Examples 2 - 6, referring to the preparation method of Example 1, replace raw material 4 therein, and the rest is the same as in Example 1. The specific structures of raw material 4, compound structures and MS [MS + 1] data are shown in the following table.

[0035]

[0036]

[0037] Performance Test Preparation of Thermosensitive Color - Developing System 1: Mix the compound containing urea structure (the compound prepared in Example 1, 7 parts), phenolic compound (hydroquinone, 30 parts), acidic substance (salicylic acid, 30 parts) and hot - melt filler (paraffin, 7 parts) by mass fraction. Heat the mixture to 100 °C until it melts and stir evenly, then cool it to room temperature and grind to obtain the thermosensitive color - developing composition.

[0038] For Thermosensitive Color - Developing Systems 2 - 6, referring to the preparation of Thermosensitive Color - Developing System 1, sequentially replace the compound containing urea structure therein with the compounds prepared in Examples 2 - 6, and the rest is the same as in Example 1.

[0039] For Thermosensitive Color - Developing System 7, referring to the preparation of Thermosensitive Color - Developing System 1, replace the compound containing urea structure therein with Comparative Compound 1, and the rest is the same as in Example 1.

[0040] Comparative Compound 1

[0041] For Thermosensitive Color - Developing System 8, referring to the preparation of Thermosensitive Color - Developing System 1, replace the compound containing urea structure therein with Comparative Compound 2, and the rest is the same as in Example 1.

[0042] Comparative Compound 2

[0043] Color reaction activation temperature and color contrast test: Thermochromic systems 1-8 were mixed with colorless substrate (thermosensitive paper) at a mass ratio of 1:5, deionized water was added to make slurry, and evenly coated on the surface of PET film (coating amount: 5g / m 2 ), dried at 50℃ and cut into 10 mm×50 mm test pieces for later use. A controllable temperature thermal gradient plate (accuracy ±1℃) was used, and the temperature gradient was set to 50-150℃, with a temperature difference of 5℃ in adjacent areas. Each temperature zone is 10 mm long, corresponding to different positions of the test piece. The test piece was flatly attached to the surface of the thermal gradient plate, pressurized at 0.5 MPa for 2 seconds, and then quickly peeled off. Immediately use a colorimeter (CIE-Lab mode) to measure the color contrast ΔE of each temperature zone 1 (relative to the unheated area). Definition ΔE 1 ≥15 is effective color development, and the lowest activation temperature of each sample (the first time ΔE 1 ≥15). Accelerated aging (85℃ / 85% RH environment, 24h) was performed on the color-developed test piece, and ΔE was re-measured. 1 The color difference retention rate was calculated based on the values, and the data are shown in the table below.

[0044]

[0045] The data in the above table show that compared with the traditional color development system, the color development system using the urea-containing compound of the present invention exhibits a lower color development activation temperature, a higher color development contrast, and better color development stability. As the compound structure changes, the color development system performance of different embodiments is slightly different, but overall they are significantly better than the control group, indicating that the new urea-containing compound can effectively reduce the reaction activation energy and improve the comprehensive performance of the color development system.

[0046] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A compound containing a urea structure, characterized in that: The compound containing a urea structure is a structure shown in Formula 1: Formula 1; The R1 is selected from: an alkyl group with 1 to 10 carbon atoms, an alkoxy group with 1 to 10 carbon atoms, an aryl group with 6 to 15 carbon atoms, and a heteroaryl group with 5 to 10 carbon atoms; Or the R1 is selected from: an aryl group with 6 to 15 carbon atoms substituted by an alkyl group with 1 to 10 carbon atoms or an alkoxy group with 1 to 10 carbon atoms; Or the R1 is selected from: a heteroaryl group having 5 to 10 carbon atoms substituted by an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms.

2. The urea-containing compound according to claim 1, characterized in that: The alkyl group having 1 to 10 carbon atoms is selected from the group consisting of methyl, ethyl, propyl and tert-butyl.

3. The urea-containing compound according to claim 1, characterized in that: The alkoxy group having 1 to 10 carbon atoms is selected from: methoxy group and ethoxy group.

4. The urea-containing compound according to claim 1, characterized in that: The aryl group having 6 to 15 carbon atoms is selected from the group consisting of phenyl, naphthyl and biphenyl.

5. The urea-containing compound according to claim 1, characterized in that: The heteroaryl group having 5 to 10 carbon atoms is selected from the group consisting of furyl and thienyl.

6. The urea-containing compound according to claim 1, characterized in that: The urea-containing compound is selected from the compounds shown in the following structures: 。 7. A method for preparing a compound containing a urea structure as claimed in claim 1, characterized in that: The following steps are involved: ； In the first step, raw material 1 and raw material 2 are synthesized by Suzuki reaction to obtain intermediate 1; In the second step, intermediate 1 is synthesized by bromination reaction to obtain intermediate 2; Step 3: Intermediate 2 and raw material 3 are synthesized by Suzuki reaction to obtain intermediate 3; Step 4: The intermediate 3 and the raw material 4 are reacted by substitution reaction to obtain a compound.

8. The method for preparing a compound containing a urea structure according to claim 7, characterized in that: The raw material 4 is selected from the compounds shown in the following structures: , , , , , , , , , , , , , , .

9. Use of a urea structure-containing compound as claimed in claim 1 in a developer.

10. Use of a urea structure-containing compound in a developer according to claim 9, characterized in that: The developer is a thermosensitive color development system, and the compound is used as an electron donor to form a color development composition with a phenolic compound and an acidic substance, wherein the mass of the compound in the composition is 0.5-15 parts, and the activation temperature of the color development reaction is 60-120°C.

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