阅读说明：本技术 一种限制域蒸发结晶制备尿素-丁二酸亚稳共晶的方法 (Method for preparing urea-succinic acid metastable eutectic by limited-domain evaporative crystallization ) 是由 于秋硕 林凯 王颖晨 贾琬莹 马哓迅 于 2020-05-26 设计创作，主要内容包括：本发明涉及一种限制域蒸发结晶制备尿素-丁二酸亚稳共晶的方法,将尿素和丁二酸按摩尔比为1:1完全溶解于去离子水中,然后将多孔玻璃浸泡到所得溶液中,浸泡完后过滤,滤饼转移至鼓风干燥箱,平铺干燥,即得到尿素-丁二酸亚稳共晶。本发明将溶液蒸发结晶局限于纳米空间内进行,改变了结晶成核的生长环境,减缓了尿素和丁二酸亚稳晶型向稳定晶型的转变速率,提高了最终产品中亚稳晶型的含量,操作简单且操作温度较低,重复性好。(The invention relates to a method for preparing urea-succinic acid metastable eutectic by limited-domain evaporative crystallization, which comprises the steps of completely dissolving urea and succinic acid in deionized water according to the molar ratio of 1:1, then soaking porous glass into the obtained solution, filtering after soaking, transferring a filter cake to an air-blast drying oven, and flatly spreading and drying to obtain the urea-succinic acid metastable eutectic. According to the invention, the solution evaporation crystallization is limited in a nanometer space, the growth environment of crystallization nucleation is changed, the conversion rate of the metastable crystal form of urea and succinic acid to the stable crystal form is slowed down, the content of the metastable crystal form in the final product is improved, the operation is simple, the operation temperature is lower, and the repeatability is good.)

1. A method for preparing urea-succinic acid metastable eutectic by limited-domain evaporative crystallization is characterized by comprising the following steps:

(1) completely dissolving urea and succinic acid in deionized water according to a molar ratio of 1:1, controlling the total concentration of the urea and the succinic acid in the solution to be 5-30 g/100g of water, then soaking porous glass with a nano pore diameter in the obtained solution, and soaking for 5-10 hours at room temperature;

(2) and (2) filtering the solid-liquid mixture obtained in the step (1), flatly paving the obtained filter cake to an air-blast drying oven for drying, wherein the drying temperature is 35-65 ℃, and the drying time is 8-30 hours, so as to obtain the urea-succinic acid metastable eutectic crystal.

2. The method for preparing the metastable eutectic of urea-succinic acid by the limited-domain evaporative crystallization of claim 1, wherein the metastable eutectic of urea-succinic acid is prepared by the following steps: in the step (1), the total concentration of urea and succinic acid in the solution is controlled to be 10-15 g/100g of water.

3. The method for preparing the metastable eutectic of urea-succinic acid by the limited-domain evaporative crystallization of claim 1, wherein the metastable eutectic of urea-succinic acid is prepared by the following steps: in the step (1), the aperture of the porous glass is 30-60 nm.

4. The method for preparing the metastable eutectic of urea-succinic acid by the limited-domain evaporative crystallization of claim 1, wherein the metastable eutectic of urea-succinic acid is prepared by the following steps: in the step (2), the drying temperature is 45-55 ℃, and the drying time is 10-12 hours.

5. The method for preparing metastable eutectic of urea-succinic acid by evaporation crystallization in limited area according to claim 1 or 4, characterized in that: in the step (2), the tiling thickness is 2-4 mm.

Technical Field

The invention belongs to the technical field of materials, and particularly relates to a method for preparing urea-succinic acid metastable eutectic by limited-domain evaporative crystallization.

Background

The urea crystal is an ultraviolet frequency doubling crystal which is practically applied, has the advantages of large birefringence and small temperature coefficient of refractive index, and can realize stable output of ultraviolet frequency doubling at room temperature. From the perspective of molecular structure, the derivative of urea or the eutectic of urea also has a nonlinear optical effect similar to that of pure urea crystals, and the construction of the eutectic of urea through molecular engineering can help to improve the nonlinear optical effect.

Eutectic crystals are crystals formed of two or more molecules, and the eutectic crystals have recently been drawing attention as a functional material for pharmaceutical, electronic, and organic chemical synthesis applications. The 2:1 eutectic of urea and succinic acid can be directly prepared by a conventional experimental method, and the 1:1 uric acid-succinic acid eutectic is prepared by a spray drying method for the first time by using Sitaram P.Veaga (Crystal Growth & Design,2010,10(8), 3302-doped 3305), which is a metastable Crystal with a Crystal structure different from that of the 2:1 stable eutectic. Vinitha (Brazilian Journal of Physics 2020,50, 192-213) states that stable and metastable eutectics of urea are possible to improve the optical application properties of urea crystals in different ways and to different extents. However, the spray drying process for preparing metastable urea butane diacid eutectic requires higher operating temperature, which may cause thermal reaction of urea.

Because of the excellent physical and chemical properties of eutectic, the preparation method of eutectic has been widely studied, and the preparation of eutectic commonly used at present mainly includes evaporative crystallization, cooling crystallization, melting crystallization, paste crystallization and solid grinding method. Different preparation methods are usually based on different eutectic formation mechanism processes, and a single preparation method is usually limited, so that the development of more preparation methods or auxiliary methods means the improvement of the probability of successfully preparing the eutectic, and in addition, the selection and comparison of more preparation methods are beneficial to the summary of eutectic preparation experience and the research of eutectic mechanism.

Although many methods for preparing the eutectic are available, many eutectic which can be predicted by theory cannot be prepared by the existing experimental method, which is due to the fact that the experimental operation is limited by the difference of physicochemical properties such as solubility, melting point and the like among the components for composing the eutectic, and the preparation method is possibly limited. More preparation methods will provide more opportunities for discovery and acquisition of new co-crystals.

Disclosure of Invention

The invention aims to provide a method for preparing urea-succinic acid metastable eutectic by limited-domain evaporative crystallization under mild conditions.

Aiming at the purposes, the technical scheme adopted by the invention comprises the following steps:

1. completely dissolving urea and succinic acid in deionized water according to a molar ratio of 1:1, controlling the total concentration of the urea and the succinic acid in the solution to be 5-30 g/100g of water, and then soaking porous glass with a nano pore diameter in the obtained solution for 5-10 hours at room temperature.

2. And (3) filtering the solid-liquid mixture obtained in the step (1), flatly paving the obtained filter cake to an air-blast drying oven for drying, wherein the drying temperature is 35-65 ℃, and the drying time is 8-30 hours, so as to obtain the urea-succinic acid metastable eutectic crystal.

In the step 1, the total concentration of urea and succinic acid in the solution is preferably controlled to be 10-15 g/100g of water.

In the step 1, the pore diameter of the porous glass is preferably 30 to 60 nm.

In the step 2, the preferable drying temperature is 45-55 ℃ and the drying time is 10-12 hours.

In the step 2, the further preferable tiled thickness is 2-4 mm.

The invention has the following beneficial effects:

1. according to the invention, the solution evaporation crystallization is limited in the nanometer space, the path of eutectic nucleation is changed, the transformation rate of the metastable crystal form of urea and succinic acid to the stable crystal form is slowed down by limiting the domain space, the content of the metastable crystal form in the final product is improved, the metastable crystal form eutectic of urea and succinic acid is successfully obtained, and the long-term storage of the metastable crystal form eutectic is facilitated.

2. The method has low requirement on experimental conditions, is easy to operate, and has low operation temperature and good repeatability.

3. The method can obtain the eutectic which can not be obtained by the conventional method, is beneficial to finding potential novel eutectic and is beneficial to improving the screening efficiency of the eutectic ligand. The invention can also be used for preparing other eutectics, not only urea and succinic acid eutectic.

Drawings

FIG. 1 is an X-ray diffraction pattern of the metastable eutectic urea-succinate prepared by the limited-domain evaporative crystallization method in example 1.

Detailed Description

The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and examples, but the scope of the present invention is not limited to these examples.