Small molecular weight organic gelling agent based on methoxybenzamide

Abstract

The invention relates to a small molecular weight organic gelling agent based on methoxybenzamide, which is prepared by the following steps: mixing stearic acid, N, N '-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, dissolving with dichloromethane under continuous stirring, then slowly adding p-anisidine, stirring, and removing the solvent under reduced pressure to obtain a white solid; and recrystallizing the white solid twice in absolute ethyl alcohol to purify, thereby obtaining the small molecular weight organic gelling agent of methoxybenzamide.

Description

Technical Field

[0001] The present invention relates to low molecular weight organic gelling agents based on anisamide. Background Art

[0002] With the rapid development of human society and technological progress, human demand for various oil products and organic solvents has increased, and oil extraction and transportation have become increasingly frequent. This has led to frequent crude oil spill accidents, discharge of industrial oily wastewater, and leakage of organic solvents (such as benzene, toluene, cyclohexane, etc.), which have seriously endangered the environment, economy and human life safety.

[0003] 1) At present, the main methods for treating oil spills on water surfaces are: on-site incineration, mechanical recovery (oil skimmers and oil booms), bioremediation, spraying chemical dispersants, physical adsorption (sponge-like porous materials), etc. However, the above methods are very limited in the face of large-scale oil spills. In addition, the supramolecular gel method using phase-selective low molecular weight organic gelator (LMWO) has attracted much attention in recent years. Phase-selective low molecular weight organic gelator (LMWO) is insoluble in water, but can gel commercial oil and various organic solvents. Oil-water separation and organic phase recovery can be achieved by simple salvage. Due to its easy synthesis, simple use and safety, it has become an ideal choice for treating surface oil spills and organic solvent leakage accidents.

[0004] 2) A variety of amino acids, cholesterol, sugars, amide (urea) phase-selective small molecular weight organic gelling agents (LMWO) have been reported one after another, but most of them still require heating-cooling or adding cosolvents. The reason why heating or cosolvents are needed is that the formation process of supramolecular gel is essentially a dissolution-clustering competition process of gelling agent molecules in related solvents. When the competition reaches a certain balance, gel is formed, otherwise it appears in a solution state or solid-liquid separation state. At room temperature, this type of gelling agent is difficult to dissolve in oil. It is necessary to pre-dissolve it in an appropriate solvent to form a free state. When it is mixed with oil, the free state gelling agent forms a 3D network structure in the oil through intermolecular forces, thereby achieving gelation.

[0005] 3) The heating-cooling or solvent addition method also has limitations in dealing with large-scale oil spills (or organic solvent leaks), and solvents may even cause secondary pollution. Therefore, one of the key issues in this field is how to achieve efficient gelation of the organic phase with small molecular weight organic gelling agent (LMWO) molecules at room temperature without solvents.

[0006] In 2008, the team of Academician Fang Yu from Shaanxi Normal University reported a series of gelling agents linked to cholesterol with L-phenylalanine, and found that it can selectively gel xylene and jet fuel in water. In particular, this type of gelling agent can achieve gelation by shaking at room temperature without heating or using a cosolvent. In 2016, the team of Professor Sureshan of India obtained the first powdered crude oil gelling agent by replacing and modifying an O atom in the structure with S in the process of enhancing the hydrophobicity of the sugar-based gelling agent molecule. Although the gelling agent has room temperature gelation properties for crude oil, the gelation time of crude oil and the properties and universality of petroleum are not detailed. Professor Zeng Huaqiang of the Singapore National Laboratory for Nanobiotechnology synthesized a series of gelling agents with fluorene methoxy functional groups based on different amino acid structures, proving the role of fluorene rings, amide bonds, chiral centers, alkyl chains, etc. in gel self-assembly. After screening, it was found that two of the gelling agents could also gel crude oil in powder form, but the time required was more than 48 hours. In 2020, Professor Song Jian of Tianjin University modified the hydroxyl and alkyl chains of 2,4-(3,4-dichlorobenzylidene)-D-glucamide compounds to obtain a series of compounds with different alkyl chains. The study found that the length of the alkyl chain has a significant effect on the gel properties. In particular, the introduction of the cis C=C structure in the side chain disrupts the compactness of the 1D fibers formed by molecular aggregation and self-assembly, forming a relatively loose aggregation mode, providing space for the penetration of solvent molecules, and finally obtaining a powder-type room temperature gelling agent with rapid gelling ability. This work provides important inspiration for the design and preparation of room temperature gelling agents. Summary of the invention

[0007] The present invention aims to provide a low molecular weight organic gelling agent based on anisamide. The gelling agent comprises the following steps: stearic acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine are mixed, dissolved in dichloromethane under constant stirring, 4-methoxyaniline, 3,4-dimethoxyaniline, m-methoxyaniline or 2,4-dimethoxyaniline is slowly added, stirred, and the solvent is removed under reduced pressure to obtain a white solid; the white solid is then recrystallized twice in anhydrous ethanol for purification to obtain four low molecular weight organic gelling agents of anisamide, which are named G1, G2, C1 or C2 respectively.

[0008] The low molecular weight organic gelling agent based on anisamide of the present invention is prepared according to the following steps:

[0009] a. Mix stearic acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, place in a round-bottom flask, and dissolve in 150 mL of dichloromethane under constant stirring to obtain a mixture;

[0010] b. After 1 hour, 4-methoxybenzene, 3,4-dimethoxyaniline, m-methoxyaniline or 2,4-dimethoxyaniline was slowly added to the mixture obtained in step a, and the mixture was stirred at 25° C. for 48 hours, and then the solvent was removed under reduced pressure at 40° C. to obtain a white solid;

[0011] c. The white solid obtained in step b was recrystallized twice in anhydrous ethanol to purify it, thereby obtaining four small molecular weight organic gelling agents of methoxybenzamide, which were named G1, G2, C1 or C2 respectively.

[0012] The low molecular weight organic gelling agent based on methoxybenzamide described in the present invention is a methoxy-substituted phenyl stearamide derivative obtained by fine-tuning the substitution position of the methoxy group and a one-step condensation reaction. Gelation studies have shown that para-substituted and 3,4-substituted derivatives are effective gelling agents that can self-assemble and gel various organic solvents.

[0013] The present invention discloses a low molecular weight organogelling agent based on anisamide, and designs and synthesizes a class of N-methoxyphenyl alkylamide derivatives with the same structural skeleton but different substitution positions on the aromatic ring. The method enables the study of the relationship between molecular structure and self-assembly properties. These compounds are designed with long alkyl chains, amide groups and aromatic rings, and produce organogels in a variety of organic solvents through van der Waals forces, hydrogen bonds and π-π stacking interactions. The gelation ability of these compounds is evaluated using an inverted tube test to show the importance of geometric changes in molecular structure on gelation properties.

[0014] The low molecular weight organic gelling agent based on anisamide of the present invention uses the inverted tube method to determine the gelling ability of all compounds in different organic solvents and commercial oils. The results are shown in Table 1:

[0015] Table 1 Gelling ability of the gelling agents G1, G2, C1 or C2 in different organic solvents

[0016]

[0017]

[0018] It can be seen from Table 1 that the small molecular weight organic gelling agents G1 and G2 of methoxybenzamide, which have p-methoxy groups, both show efficient gelling ability, with the minimum gelling concentration (MGC) of G1 ranging from 1.21 to 2.54% w / v and that of G2 ranging from 1.42 to 2.34% w / v. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The process flow chart of the present invention, wherein A is the synthesis process; B is the structural formula of the synthesized compound;

[0020] Figure 2 The gelation effects of the organogelator G1 synthesized in the present invention in different organic solvents, wherein A is the inverted tube test of the organogel of the gelator organogelator G1 in different organic solvents; B and C are the morphologies formed by the organogelator G1 under an electron scanning microscope, showing band-like aggregation with a high aspect ratio; D and E are the morphologies formed by the organogelator G2 under an electron scanning microscope;

[0021] Figure 3 The rheological property diagrams of the organogelator G1 and the organogelator G2 of the present invention, wherein A: strain scanning at a fixed frequency (1 Hz); B: frequency scanning diagram at a fixed strain of 0.02%. DETAILED DESCRIPTION

[0022] Example 1

[0023] a. Mix 6 mmol, 1.704 g of stearic acid, 6 mmol, 1.236 g of N,N'-dicyclohexylcarbodiimide and 1.25 mmol, 0.1525 g of 4-dimethylaminopyridine, place in a round-bottom flask, and dissolve in 150 mL of dichloromethane under constant stirring to obtain a mixture;

[0024] b. After 1 hour, 5 mmol, 0.616 g of 4-methoxyaniline was slowly added to the mixture obtained in step a, and the mixture was stirred at 25° C. for 48 hours, and then the solvent was removed under reduced pressure at 40° C. to obtain a white solid;

[0025] c. The white solid obtained in step b was recrystallized twice in anhydrous ethanol to purify it, thereby obtaining a small molecular weight organic gelling agent of methoxybenzamide, which was named G1.

[0026] Example 2

[0027] a. Mix 6 mmol, 1.704 g of stearic acid, 6 mmol, 1.236 g of N,N'-dicyclohexylcarbodiimide and 1.25 mmol, 0.1525 g of 4-dimethylaminopyridine, place in a round-bottom flask, and dissolve in 150 mL of dichloromethane under constant stirring to obtain a mixture;

[0028] b. After 1 hour, 5 mmol, 0.766 g, of 3,4-dimethoxyaniline was slowly added to the mixture obtained in step a, and the mixture was stirred at 25° C. for 48 hours, and then the solvent was removed under reduced pressure at 40° C. to obtain a white solid;

[0029] c. The white solid obtained in step b was recrystallized twice in anhydrous ethanol to purify, thereby obtaining a low molecular weight organic gelling agent of methoxybenzamide, which was named G2.

[0030] Example 3

[0031] a. Mix 6 mmol, 1.704 g of stearic acid, 6 mmol, 1.236 g of N,N'-dicyclohexylcarbodiimide and 1.25 mmol, 0.1525 g of 4-dimethylaminopyridine, place in a round-bottom flask, and dissolve in 150 mL of dichloromethane under constant stirring to obtain a mixture;

[0032] b. After 1 hour, 5 mmol, 0.616 g of m-methoxyaniline was slowly added to the mixture obtained in step a, and the mixture was stirred at 25° C. for 48 hours, and then the solvent was removed under reduced pressure at 40° C. to obtain a white solid;

[0033] c. The white solid obtained in step b was recrystallized twice in anhydrous ethanol to purify, thereby obtaining a low molecular weight organic gelling agent of methoxybenzamide, which was named C1.

[0034] Example 4

[0035] a. Mix 6 mmol, 1.704 g of stearic acid, 6 mmol, 1.236 g of N,N'-dicyclohexylcarbodiimide and 1.25 mmol, 0.1525 g of 4-dimethylaminopyridine, place in a round-bottom flask, and dissolve in 150 mL of dichloromethane under constant stirring to obtain a mixture;

[0036] b. After 1 hour, 5 mmol, 0.766 g of 2,4-dimethoxyaniline was slowly added to the mixture obtained in step a, and the mixture was stirred at 25° C. for 48 hours, and then the solvent was removed under reduced pressure at 40° C. to obtain a white solid;

[0037] c. The white solid obtained in step b was recrystallized twice in anhydrous ethanol to purify, thereby obtaining a low molecular weight organic gelling agent of methoxybenzamide, which was named C2.

[0038] Example 5

[0039] The low molecular weight organic gelling agent based on anisamide of the present invention comprises:

[0040] Figure 2 A shows the inverted tube test of the G1 organogelator of Example 1 from different solvents. All gels formed by G1 of Example 1 are opaque and do not flow when inverted. In order to further reveal the self-assembled aggregate structure, the morphology of the aggregates was studied by SEM characterization; Figure 2 As shown in BC, the morphology of the organogelator G1 of Example 1 can be clearly observed, showing ribbon-like aggregation with a high aspect ratio; the diameter of the fiber is recorded to be about 1 μm;

[0041] The organogelator G2 of Example 2 formed the same fiber network with a more compact structure ( Figure 2 DE), indicating that the organic gelling agent G2 of Example 2 provides enhanced intermolecular forces, resulting in denser three-dimensional (3D) growth of fibers; therefore, compared with G2 of Example 2, G1 of Example 1 exhibits higher MGC values ​​and reduced gelation ability; in all gelling agents, the network structure exhibits different degrees of cross-linking, and these cross-linked 1D nanofibers form a 3D network by entanglement and fixation of solvents;

[0042] The rheological properties of the organogelators of Example 1 G1 and Example 2 G2 in DMSO (at a concentration of 2.0% w / v) were evaluated using a rheometer; strain sweeps were performed at a fixed frequency (1 Hz) in the range of 0.01-100% strain to define the viscoelastic linear region; it can be observed that in the viscoelastic linear region, the storage modulus (G′) is greater than the loss modulus (G″); when the critical strain value is reached, G′ and G″ drop sharply, and G″ is greater than G′ in the nonlinear region, indicating that the organogel exhibits solid-like behavior in the linear region; it is worth noting that the G2 organogelator of Example 2 exhibits a wider linear viscoelastic region than the G1 organogelator of Example 1, which indicates that the structure of the G2 organogelator of Example 2 Not easily damaged; in the frequency scanning experiment at a fixed strain (0.02%), it can be observed that the G′ and G″ of the G1 gel of Example 1 and the G2 gel of Example 2 are independent of the frequency in all cases; in addition, at any frequency value, the value of G′ is much higher than G″, confirming the elastic properties of the organic gel; it is worth noting that the G′ value of the G2 gel of Example 2 is about 106Pa, which is higher than the G1 organic gelling agent of Example 1; the larger G′ value means that the formed organic gelling agent has solid-like properties, which indicates that there is a strong intermolecular interaction between the G2 molecules of Example 2; the mechanical property results are consistent with the SEM findings, and the lack of intermolecular forces in the G1 of Example 1 leads to a reduced degree of crosslinking in its 3D structure.

Claims

1. A low molecular weight organic gelling agent based on anisamide, characterized in that Follow these steps: a. Mix stearic acid, N,N'-dicyclohexylcarbodiimide and 4-dimethylaminopyridine, place in a round-bottom flask, and dissolve in 150 mL of dichloromethane under constant stirring to obtain a mixture; b. After 1 hour, 4-methoxyaniline, 3,4-dimethoxyaniline, m-methoxyaniline or 2,4-dimethoxyaniline was slowly added to the mixture obtained in step a, and the mixture was stirred at 25° C. for 48 hours, and then the solvent was removed under reduced pressure at 40° C. to obtain a white solid; c. The white solid obtained in step b was recrystallized twice in anhydrous ethanol to purify it, thereby obtaining four small molecular weight organic gelling agents of methoxybenzamide, which were named G1, G2, C1 or C2 respectively.

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