A compound containing a urea structure, a preparation method thereof, and applications in a chromogenic agent

Abstract

The present invention discloses a compound containing a urea structure, a preparation method thereof, and an application in a developer, which relates to the technical field of developers. The compound containing a urea structure has the structure shown in Formula 1. The compound containing a urea structure is synthesized through multiple steps including a Suzuki reaction, a bromination reaction, and a substitution reaction. This compound is used as an electron donor in a thermosensitive color development system and forms a color development composition with phenolic compounds and acidic substances, and the activation temperature is as low as 60 - 120 °C. Its urea group structure stabilizes the reaction intermediate through a hydrogen bond network, enhances the electron transfer efficiency, and significantly improves the color development sensitivity; the aryl / heteroaryl substituents optimize the color development contrast through a conjugation effect, and at the same time, the hot-melt filler synergistically ensures the stability of the system. Compared with traditional developers, the present invention has both low-temperature activation, high color development intensity, and excellent weather resistance, and is suitable for fields such as thermosensitive printing and anti-counterfeiting materials, solving the defects of high reaction temperature and insufficient stability in the prior art.

Description

Technical Field

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

[0002] In today's society, developers play a crucial role in many fields, such as thermal printing paper, chemical sensors, anti-counterfeiting materials, etc. Although traditional developers can basically meet the color development requirements, there are many problems that need to be solved urgently. On the one hand, its color development sensitivity is limited, and it is difficult to present clear color changes in complex environments or at low concentrations, affecting the detection accuracy and the visual effect of materials; on the other hand, the color development stability is poor, and it is easily interfered by factors such as temperature, humidity, and light, resulting in the gradual fading or deviation of the color, shortening the service life of related products.

[0003] Taking the thermal 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 undergo a color development reaction with phenolic compounds, there is a lack of sufficient reaction activity, and a relatively high temperature is required to activate the color development process. This not only increases energy consumption but also limits its application in temperature-sensitive scenarios. At the same time, the compatibility of some traditional electron donors with phenolic compounds and acidic substances is poor, easily leading to stratification or precipitation in the color development system, further affecting the uniformity and stability of the color development effect.

[0004] In view of this, the development of novel compounds containing a urea structure for developers has become a research hotspot and urgent need in this field. Compounds containing a urea structure, due to their unique chemical properties, are expected to form a more stable and sensitive color development composition with phenolic compounds and acidic substances, making up for the defects of traditional developers, expanding their application scope 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 address the problems of low color development sensitivity, poor stability, and harsh reaction conditions of developers in the prior art, and to provide a compound containing a urea structure, a preparation method thereof, and an application in a developer, which has high color development sensitivity, good stability, and can activate the color development reaction at a relatively low temperature.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is: a compound containing a urea structure, and the compound containing a urea structure has the structure shown in Formula 1:

[0007] Formula 1;

[0008] The R1 is selected from: an alkyl group with 1 - 10 carbon atoms, an alkoxy group with 1 - 10 carbon atoms, an aryl group with 6 - 15 carbon atoms, a heteroaryl group with 5 - 10 carbon atoms;

[0009] Or R1 is selected from: an aryl group having 6 to 15 carbon atoms substituted by an alkyl group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms;

[0010] Or 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.

[0011] Furthermore, the alkyl group having 1 to 10 carbon atoms is selected from: methyl, ethyl, propyl, tert-butyl.

[0012] Furthermore, the alkoxy group having 1 to 10 carbon atoms is selected from: methoxy, ethoxy.

[0013] Furthermore, the aryl group having 6 to 15 carbon atoms is selected from: phenyl, naphthyl, biphenyl.

[0014] Furthermore, the heteroaryl group having 5 to 10 carbon atoms is selected from: furyl, thienyl.

[0015] Furthermore, the compound containing a urea structure is selected from the compounds shown in the following structures:

[0016] .

[0017] A method for preparing a compound containing a urea structure, comprising the following steps:

[0018] ;

[0019] In the first step, intermediate 1 is synthesized by the Suzuki reaction of raw material 1 and raw material 2;

[0020] In the second step, intermediate 2 is synthesized by the bromination reaction of intermediate 1;

[0021] In the third step, intermediate 3 is synthesized by the Suzuki reaction of intermediate 2 and raw material 3;

[0022] In the fourth step, the compound is synthesized by the substitution reaction of intermediate 3 and raw material 4.

[0023] Furthermore, raw material 4 is selected from the compounds shown in the following structures:

[0024] , , , , , , , , , , , , , , .

[0025] Application of a compound containing a urea structure in a developer.

[0026] Furthermore, the developer is a thermosensitive color-developing system, and the compound containing a urea structure serves 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.

[0027] Furthermore, the thermosensitive color-developing system consists of 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.

[0028] Furthermore, the phenolic compound is selected from at least one of bisphenol A, hydroquinone, resorcinol, and 4-hydroxybenzoate.

[0029] Furthermore, the acidic substance is selected from at least one of stearic acid, salicylic acid, p-toluenesulfonic acid, and dodecylbenzenesulfonic acid.

[0030] Furthermore, the hot-melt filler is selected from at least one of paraffin wax, microcrystalline wax, and polyethylene wax.

[0031] 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.

[0032] The compound containing a urea structure described in the present invention serves 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 transfer 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 reaction activation energy, thereby realizing 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.

[0033] The compound containing 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 an alkyl / alkoxy group, the solubility can be improved to ensure color development uniformity. When it is substituted by an aryl / heteroaryl group, 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.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] 1. Improved color development sensitivity: The compound containing a urea structure significantly reduces the activation temperature of the color development reaction by enhancing the electron transfer efficiency, solving the bottleneck of the traditional technology that requires high temperature activation.

[0036] 2. Optimized 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.

[0037] 3. Extended application compatibility: Compared with traditional electron donors, the compound containing a urea structure of 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

[0038] Figure 1 It is a preparation method of the compound containing a urea structure according to the present invention. Detailed Embodiments

[0039] The technical solutions of the present invention will be clearly and completely described below with reference to the drawings in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art without making creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention. Example 1

[0040] Synthesis of Compound 1:

[0041] ;

[0042] 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.

[0043] 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 filter was filtered and washed with 300 mL of saturated NaHCO3 aqueous solution. The organic phase was washed with 200 mL of brine, dried over anhydrous MgSO4, and then spin-dried for column chromatography, using a mixture of petroleum ether and dichloromethane as an eluent to finally obtain 16.99 g of intermediate 2. MS[MS+1]: 637.

[0044] 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.

[0045] 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.

[0046] Compound 11 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).

[0047] Examples 2 - 6

[0048] For the compounds synthesized in Examples 2 - 6, referring to the preparation method of Example 1, replace raw material 4 therein, and the rest remains 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.

[0049]

[0050]

[0051] Performance testing

[0052] Preparation of thermosensitive color - developing system 1: Mix the compound containing urea structure (7 parts of the compound prepared in Example 1), phenolic compound (hydroquinone, 30 parts), acidic substance (salicylic acid, 30 parts), and heat - fusible filler (paraffin, 7 parts) according to mass parts. Heat the mixture to 100 °C to melt and stir evenly, then cool to room temperature and grind to obtain the thermosensitive color - developing composition.

[0053] 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 remains the same as in Example 1.

[0054] 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 remains the same as in Example 1.

[0055] Comparative Compound 1.

[0056] 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 remains the same as in Example 1.

[0057] Comparative Compound 2.

[0058] Color reaction activation temperature and color contrast test:

[0059] 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.

[0060]

[0061] 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.

[0062] 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 has the structure shown in Formula 1: Formula 1; The R1 is selected from: alkyl groups with 1-10 carbon atoms, alkoxy groups with 1-10 carbon atoms, aryl groups with 6-15 carbon atoms, and heteroaryl groups with 5-10 carbon atoms; or the R1 is selected from: aryl groups with 6-15 carbon atoms substituted by alkyl groups with 1-10 carbon atoms and alkoxy groups with 1-10 carbon atoms; or the R1 is selected from: heteroaryl groups with 5-10 carbon atoms substituted by alkyl groups with 1-10 carbon atoms and alkoxy groups with 1-10 carbon atoms.

2. The compound with a urea structure according to claim 1, characterized in that, The alkyl groups with 1-10 carbon atoms are selected from: methyl, ethyl, propyl, tert-butyl.

3. The compound with a urea structure according to claim 1, characterized in that, The alkoxy groups with 1-10 carbon atoms are selected from: methoxy, ethoxy.

4. A compound containing a urea structure according to claim 1, characterized in that, The aryl groups with 6-15 carbon atoms are selected from: phenyl, naphthyl, biphenyl.

5. A compound containing a urea structure according to claim 1, characterized in that, The heteroaryl groups with 5-10 carbon atoms are selected from: furyl, thienyl.

6. A compound containing a urea structure according to claim 1, characterized in that, The compound containing a urea structure is selected from the compounds shown in the following structures: 。 7. A method for preparing a compound containing a urea structure as described in claim 1, characterized in that, Including the following steps: ； 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.

8. A 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 compound containing a urea structure as described in Claim 1 in a developer.

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

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