Preparation method of symmetric gemini surfactant

Abstract

The invention relates to a preparation method of a symmetric gemini surfactant. According to the invention, dodecyl tertiary amine, 1, 2-dibromoethane and 1, 4-dibromobutane are used as raw materials, and the cationic surfactants C12-2-C12 and C12-4-C12 are synthesized in one step through a nucleophilic substitution reaction. The two synthesized products are characterized, the surface tension of the products under different concentrations is tested, the CMC value of the products is calculated, and compared with a common surfactant, the CMC value of the products is higher, and better performance is achieved; the surface tension is detected under salt with different temperatures and different concentrations, so that the temperature resistance and the salt resistance are explored. The final experiment and detection results show that the synthesized cationic Gemini surfactant has good performance and has great market potential in the tertiary oil recovery process as an oil displacement agent.

Description

Technical Field

[0001] The invention provides a method for preparing a symmetrical gemini surfactant, which specifically adopts a classical nucleophilic substitution reaction to synthesize a novel diquaternary ammonium salt symmetrical gemini surfactant under appropriate conditions. Background Art

[0002] Oil is an important resource that is indispensable to our daily life and industrial development. It is very necessary for our food, clothing, housing, transportation, and national defense weapons. Oil is formed by the natural decomposition of animal and plant corpses over tens of thousands of years. It is a non-renewable fossil energy source, and its reserves on the earth are constantly decreasing. New energy is still in the research and development stage, and it is difficult to replace oil as the main raw material for industrial production, so improving the oil recovery rate has become the most important research topic at present. Cationic surfactants can greatly increase the oil recovery rate as oil displacement agents.

[0003] Surfactants are very important interfacial modifiers. Usually, adding a small amount of surfactants to a solution can significantly reduce the surface tension of the solution. When the concentration of surfactants in the solution increases to a certain value, micelles will be formed in the solution, which will have a series of properties such as wetting, dewetting, emulsification, demulsification, and washing. They are widely used in detergents, oil displacement agents, emulsifiers, and phase transfer catalysis.

[0004] Surfactant is a substance with an asymmetric structure. It is composed of a hydrophilic group (oleophobic group) at the head and a hydrophobic group (lipophilic group) at the tail. Due to this special structure, it is also called amphiphilic. The polarity of the hydrophilic group is strong and it is easily soluble in water, amino acids, ethanol and other substances; the polarity of the lipophilic group is relatively weak and it is easily soluble in organic substances. Therefore, the physicochemical properties of surfactants depend to a large extent on the proportion of hydrophilic groups and lipophilic groups.

[0005] Gemini surfactants refer to surfactants formed by chemical bonding of two or more surfactant groups through polar groups and then through linking groups. Gemini surfactants are a type of cationic surfactant, which generally have hydrophilic groups at both ends and cationic groups at the head. This type of surfactant with an amphiphilic structure is called a gemini surfactant. It has a very low CMC value and high interfacial activity. It can effectively reduce the water interfacial tension at a relatively low concentration, achieving an ideal oil displacement effect, and becoming an oil displacement agent with excellent oil displacement performance. At the same time, it also has excellent emulsification, wetting, and penetration effects, and can also be used as an emulsifier and wetting agent in textiles and cosmetics.

[0006] The symmetrical gemini surfactant of the synthetic quaternary ammonium salt of the present invention has the advantages of higher surface activity, lower micelle critical concentration, better solubilization effect, stronger temperature and salt resistance, easy raw material availability and simple synthesis, etc. compared with common surfactants, and has great development prospects. Summary of the invention

[0007] The purpose of the present invention is to design a method for preparing a symmetrical gemini surfactant. To achieve this requirement, the present invention mainly synthesizes cationic surfactants C12-2-C12 and C12-4-C12 in one step by using dodecaamine, 1,2-dibromoethane and 1,4-dibromobutane as raw materials through a nucleophilic substitution reaction.

[0008] The synthesis method mainly includes the following:

[0009] Type 1: Take a 100ml three-necked flask, add 1,2-dibromoethane and dodecaamine, use 8ml of anhydrous ethanol as solvent, put in a rotor, stir under a magnetic stirring device, and slowly heat to 75°C, keep the temperature constant, and reflux for 8h. After the reaction is completed, remove the solvent by rotary evaporation. Recrystallize with ethyl acetate and then dry to obtain the target product C12-2-C12.

[0010] Type 2: 1,4-dibromobutane and dodeca-tert-amine are placed in a 100 ml three-necked flask. 8 ml of anhydrous ethanol is added as a solvent, a rotor is placed, stirring is turned on, and the temperature is slowly raised to 75°C, and a constant reflux reaction is maintained for 10 hours. After the reaction is completed, the mixture is cooled to room temperature, and the solvent is removed by vacuum rotary evaporation to obtain a white viscous substance. Recrystallization is performed using acetone: anhydrous ethanol = 7:3, and the configured solvent is used for recrystallization, followed by drying to obtain the target product C12-4-C12.

[0011] In the present invention, in the first preparation process, the molar ratio of 1,2-dibromoethane to dodeca-tertiary amine is 1:2.17, the reaction time is 8 hours, the reaction temperature is 75° C., and the cationic surfactant C12-2-C12 is obtained.

[0012] In the present invention, in the first preparation process, the molar ratio of 1,4-dibromobutane to dodecanamine is 1:2.15, the reaction time is 10 hours, the reaction temperature is 75° C., and the cationic surfactant C12-4-C12 is obtained.

[0013] The present invention is a symmetrical gemini surfactant of a diquaternary ammonium salt type used in tertiary oil recovery, which has the following outstanding advantages in preparation and application:

[0014] 1. Gemini surfactants can more effectively reduce interfacial tension due to their tighter surface arrangement; at the same time, this type of surfactant is more likely to aggregate to form micelles; it has strong viscosity characteristics; foam performance, emulsification performance, and wettability are also better; soap calcium dispersibility is stronger; and the compounding effect is better.

[0015] 2. The prepared asymmetric gemini surfactant of diquaternary ammonium salt has higher surface activity than general surfactants; and has a low CMC value, is easy to form micelles, and has a good solubilization effect; has stronger adsorption performance and better temperature and salt resistance; the raw materials are easily available, the operation is convenient, and it has a very broad application prospect. DETAILED DESCRIPTION

[0016] The present invention is further described below by way of implementation examples, the purpose of which is to provide a better understanding of the content of the present invention.

[0017] Embodiment 1:

[0018] Take a 100ml three-necked flask, insert a thermometer and a condenser, and add 1.878g (0.01mol) of 1,2-dibromoethane and 4.628g (0.0217mol) of dodecaned amine at a molar ratio of 1,2-dibromoethane: dodecaned amine = 1:2.17. Add 8ml of anhydrous ethanol as a solvent, put in a rotor, stir under a magnetic stirring device, and slowly heat to 75°C, keep the temperature constant, and reflux for 8h. As the reaction proceeds, the color of the reaction solution gradually darkens. After 6 hours of reaction, take 0.5ml of the reaction solution and add an equal amount of water to dissolve it. A white solid is produced in the lower layer. Take another test tube and add 1ml of the prepared 1% bromophenol blue and 1ml of chloroform. Take the reaction solution added with clean water and add it to the test tube. The solution changes from yellow to blue. Then detect that the pH after diluting the reaction solution is alkaline, which can identify the formation of the target product quaternary ammonium salt. After the reaction is completed, move the reaction solution to a 100ml round-bottom flask and cool it to room temperature. The mixture was placed in a rotary evaporator, set at 50°C, pressure -0.1 MPa, and speed 90 rpm, and the solvent was evaporated for 10 minutes. The mixture was recrystallized with ethyl acetate and dried to obtain the target product.

[0019] Embodiment 2: Take 100ml three-necked flask, insert thermometer and condenser, add 1,4-dibromobutane 2.1591g (0.01mol) and dodecanamine 4.5881g (0.0215mol) in the molar ratio of 1,4-dibromobutane: dodecanamine = 1: 2.15. Add 8ml of anhydrous ethanol as solvent, put in rotor, turn on stirring and slowly heat to 75°C, keep constant reflux reaction for 10 hours. The solution changes from transparent colorless to light yellow transparent color, stop heating, move the reaction solution into a 100ml round-bottom flask and cool to room temperature. Put in a rotary evaporator and set the temperature to 55°C, air pressure -0.1MPa, speed 90rpm, and steam the solvent for 15 minutes to steam out the solvent, which is a white viscous substance. Recrystallization uses acetone: anhydrous ethanol = 7: 3, and the solvent configured is recrystallized 1,2-bis (dodecylamino) ethane-1,2-disulfonic acid sodium and other series of products for purification. Stir with a glass rod until the product is completely dissolved in chloroform and the solution turns red. Pour ethyl acetate until no solid precipitates. Filter to obtain the final target compound. Repeat the above operation 3 times to finally obtain a product with a purity greater than 96%.

Claims

1. A method for preparing a symmetrical gemini surfactant, which is achieved by a nucleophilic substitution reaction and purified, characterized in that Follow these steps: The first one: quaternization reaction of 1,2-dibromoethane and dodecanedrine to obtain a symmetrical gemini-type interface modifier C12-2-C12. The second method: quaternization reaction of 1,4-dibromobutane and dodecylamine to obtain a symmetrical gemini-type interface modifier C12-4-C12.

2. The preparation method of type 1 according to claim 1, characterized in that: The molar ratio of 1,2-dibromoethane to dodecanamine is 1:2.17, the reaction time is 8 hours, and the reaction temperature is 75°C.

3. The preparation method of type 2 according to claim 1, characterized in that: The molar ratio of 1,4-dibromobutane to dodecanamine is 1:2.15, the reaction time is 10 hours, and the reaction temperature is 75°C.