CN103382157A - Process for preparing hexadecyl methyl 2-hydroxyethyl ammonium bromide - Google Patents

Abstract

The invention discloses a preparation method of cetylmethyl dihydroxyethyl ammonium bromide. Including: weighing N-methyldiethanolamine and hexadecane bromide, placing them in a three-necked flask equipped with a mechanical stirrer, a reflux condenser, and a thermometer, and heating the oil bath for reaction; The crude product was recrystallized with a mixture of water and ethanol, and bright white crystals were obtained by suction filtration, which was obtained after vacuum drying. The present invention uses N-methyldiethanolamine and hexadecane bromide as raw materials, and adopts a solvent-free method to synthesize hexadecylmethyldihydroxyethylammonium bromide quaternary ammonium salt surfactant. The preparation process does not use a solvent, Thereby reducing the pollution caused by organic solvents and the cost of recycling. The prepared product has good solubilizing performance, foaming performance and emulsifying performance.

Description

A kind of preparation method of hexadecyl methyl dihydroxyethyl ammonium bromide

technical field

The invention relates to a preparation method of cetylmethyl dihydroxyethyl ammonium bromide.

Background technique

There has been a long history of research on cationic surfactants in the world. As typical cationic surfactants, quaternary ammonium salts can be widely used in leveling agents, antistatic agents, fabric softeners, antibacterial agents, etc., and have excellent Conditioning, moisturizing, thickening, foaming and emulsifying functions.

Hexadecylmethyldihydroxyethylammonium bromide has a chemical formula of C21H46BrNO2 and a structural formula as shown in formula (I).

Hexadecylmethyldihydroxyethylammonium bromide is an important cationic surfactant. The existing preparation methods all react with the participation of solvents. Most of the organic solvents are harmful to the human body and are difficult to recycle. Environmental protection has become more and more important to all walks of life. The goal is to reduce or eliminate pollution in chemical production. Solvent-free synthesis does not use organic solvents, which can not only speed up the reaction efficiency but also reduce the pollution caused by solvents and the cost of recycling.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and a kind of preparation method of hexadecylmethyl dihydroxyethyl ammonium bromide participating in without solvent is provided.

In order to achieve the above object, the present invention adopts the following technical solutions:

A preparation method of cetyl methyl dihydroxyethyl ammonium bromide, comprising the steps of:

Weigh N-methyldiethanolamine and hexadecane bromide and place them in a three-necked flask equipped with a mechanical stirrer, a reflux condenser, and a thermometer, and heat in an oil bath for reaction; after fully reacting, use ethyl acetate and absolute ethanol to The crude product was recrystallized from the mixed solution, and bright white crystals were obtained by suction filtration, which was obtained after vacuum drying.

In the above preparation method, the molar ratio of hexadecane bromide to N-methyldiethanolamine is 0.5-3.5:1. The preferred molar ratio is 0.8-1.5:1, and the best molar ratio is 1.1:1.

In the above preparation method, the reaction temperature is preferably 100-120°C, and the optimum temperature is 110°C.

In the above preparation method, the reaction time is preferably 110 min.

In the above preparation method, the number of times of the recrystallization is preferably 3 times.

In the above preparation method, the temperature of the vacuum drying is preferably 50°C.

In the above preparation method, in the mixture of ethyl acetate and absolute ethanol, the volume ratio of ethyl acetate to absolute ethanol is 1:1-10.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention uses N-methyldiethanolamine and hexadecane bromide as raw materials, and adopts a solvent-free method to synthesize hexadecylmethyldihydroxyethylammonium bromide quaternary ammonium salt surfactant. The preparation process does not use a solvent, Thereby reducing the pollution caused by organic solvents and the cost of recycling. The prepared product has good solubilizing performance, foaming performance and emulsifying performance.

Description of drawings

Fig. 1 is the infrared absorption spectrum of synthetic product;

Fig. 2 is the proton nuclear magnetic resonance spectrum (1H NMR) figure of synthetic product;

Fig. 3 is the mass spectrogram of synthetic product;

Fig. 4 is the impact of time on MDEA transformation rate;

Figure 5 is a graph showing the relationship between optical density and benzene content.

Detailed ways

Reagents and instruments:

N-methyldiethanolamine (, CR, Guangdong Maoming Zhonghe Chemical Plastic Co., Ltd.; cetyl bromide, CR, Guangdong Maoming Zhonghe Chemical Plastic Co., Ltd.; dialkyl ester group hydroxyethyl methyl sulfate ammonium (EQ), AR, Tianjin Xianguang Chemical Co., Ltd.; Dioctadecyldimethylammonium Chloride (D1821), AR, Yixing Kailida Chemical Co., Ltd.; all other reagents are AR.

Fourier transform infrared spectrometer, TENSOR27, French BRUKER company; vacuum drying oven, DZG-6050SA, Shanghai Senxin Experimental Instrument Co., Ltd.; collector type constant temperature heating magnetic stirrer, DF-101S, Gongyi City Yuhua Instrument Co., Ltd.; circulating water Type vacuum pump, SHZ-D (Ⅲ), Gongyi Yingyu Yuhua Instrument Factory. BZY-1 automatic interfacial tensiometer, Zibo Boshan Haifen Instrument Factory; WRS-1B digital melting point instrument, Shanghai Precision Scientific Instrument Co., Ltd.

Example 1:

Take by weighing N-methyldiethanolamine and hexadecane bromide and place in the three-necked flask equipped with mechanical stirrer, reflux condenser, thermometer, the mol ratio of hexadecane bromide and N-methyldiethanolamine is 1.1: 1. React under heating in an oil bath, the reaction temperature is 110°C. After reacting for 110 min, the crude product was recrystallized three times with a mixture of ethyl acetate and absolute ethanol, and then filtered with suction to obtain bright white crystals, which were obtained after vacuum drying at 50°C. Its melting point was measured to be 120.09°C.

Example 2:

Take by weighing N-methyldiethanolamine and hexadecane bromide and place in the three-necked flask equipped with mechanical stirrer, reflux condenser, thermometer, the mol ratio of hexadecane bromide and N-methyldiethanolamine is 1.2: 1. React under heating in an oil bath, the reaction temperature is 120°C. After reacting for 110 min, the crude product was recrystallized three times with a mixture of ethyl acetate and absolute ethanol, and then filtered with suction to obtain bright white crystals, which were obtained after vacuum drying at 50°C. Its melting point was measured to be 121.03°C.

Example 3:

Take by weighing N-methyldiethanolamine and hexadecane bromide and place in the three-necked flask equipped with mechanical stirrer, reflux condenser, thermometer, the mol ratio of hexadecane bromide and N-methyldiethanolamine is 0.9: 1. React under heating in an oil bath, the reaction temperature is 100°C. After reacting for 110 min, the crude product was recrystallized three times with a mixture of ethyl acetate and absolute ethanol, and then filtered with suction to obtain bright white crystals, which were obtained after vacuum drying at 50°C. Its melting point was found to be 121°C.

Embodiment 4: identify the product obtained in Example 1

Product analysis method: adopt hydrochloric acid-ethanol titration method to measure the transformation rate of N-methyldiethanolamine in the test. The formation of the product was preliminarily analyzed by thin-layer chromatography, and the cationic active substance existed in the product by bromophenol blue method. The purity of the purified product was determined to be greater than 99% by two-phase titration.

The product was analyzed by IR (KBr pellet), ¹ HNMR (CD ₃ SOCD ₃ ) and positive ion mode (ESI ⁺ /ES) of electrospray mass spectrometry, and the structure and molecular weight of the product were identified.

Determination of surface tension: the product was formulated into a 0.1% aqueous solution, and the surface tension of the quaternary ammonium salt was measured by the platinum ring method.

Clough point test: Prepare the product into a 0.1% aqueous solution, put it in saturated saline at a temperature lower than 0°C, and observe that there are crystals precipitated.

Determination of foaming ability: Standard GB/T7462-1994, improved ROSS-Mise is used to measure foaming and foam stabilizing ability.

Determination of compatibilization ability: the product is prepared into an aqueous solution with an intolerant concentration to increase the dissolving ability of benzene in distilled water. When the content of benzene reaches a certain amount, the system will become turbid and stratified. When the optical density of the system is measured with a UV-visible spectrophotometer, the optical density will increase significantly, thus the solubilizing ability of the product can be measured. Add 0-0.4mL nine samples of benzene to 50ml of the test solution with a concentration of 0.002mol/L respectively, and measure the absorbance after standing for 24 hours.

Determination of emulsifying power performance: measured by quantitative method GB11543-1989. Infrared absorption spectrum: It can be seen from Figure 1 that the absorption peak of -OH is at the wavelength of 3294cm ^-1 , and the C—H stretching vibration absorption peak of methyl and methylene is respectively at the wavelength of 2921cm ^-1 and 2852cm ^-1 . ^-1 is the C—N bond, 1164cm ^-1 is the methylene shear absorption peak, 1050cm ^-1 is the methyl shear absorption peak, and the last 628cm ^-1 is the —(CH2)n— absorption peak. This can be initially identified as the expected product.

Nuclear Magnetic Resonance Spectrum: It can be obtained from Figure 2 that the number of hydrogen atoms is 42, which is the same as the assumed product structure. From Figure 2, it can be concluded that the H chemical shift δ on each group is: R-CH ₃ *, 0.82～0.84, 3H, N+(CH ₂ ) ₄ -(CH ₂ *) ₉ -CH ₃ , 1.21～1.23, 18H , N+CH ₂ CH ₂ (CH ₂ *) ₂ , 1.25～1.30, 4H, CH ₃ N+-CH ₂ -CH ₂ *, 1.70, 2H, N+-CH ₃ *, 3.29, 3H, N+-CH ₂ - CH ₂ *R, 3.50～3.52, 2H, N-CH ₂ -CH ₂ *-OH, 3.65～3.93, 4H, N-CH ₂ *-CH ₂ -OH, 4.06, 4H, OH*, 4.72～4.74, 2H. The chemical shift of the hydrogen proton of the product is in one-to-one correspondence with the structure of the product, so it can be determined that the product obtained in Example 1 is the target compound.

Mass spectrometry: Scan the product with a mass spectrometer, use ESI as the ion source, and use positive ion mode. The result is shown in Figure 3, 315.9 (M+H)+, which is the molecular weight of the target product cation, which is 316.

Embodiment 5: the performance test of embodiment 1 product

Surface tension: The surface tension of the aqueous solution of the product was measured to be 24.8N·m-1, and the surface tension of water was significantly reduced from 71.5N·m ^-1 to 24.8mN·m ^-1 . It can be seen that the product has excellent surface activity and is a A new surfactant with better surface properties.

Krafft point: when the aqueous solution is cooled to below 0°C, no substance precipitates out, which indicates that the Krafft point of the product is below 0°C.

Product foam properties: cetyl methyl dihydroxyethyl ammonium bromide (TMDAB), dialkyl ester group hydroxyethyl methyl ammonium methyl sulfate (EQ) and octadecyl dimethyl ammonium chloride ( DODMAC) foam performance comparison, it can be seen that compared with the commonly used surfactants in the market, the experimental product has better foaming ability but general foam stabilizing ability, and the foam height drops significantly after 5 minutes. The results are shown in Table 1:

The foam performance of table 1 surfactant

Benzene solubilization performance of the product: measure the solutions containing different concentrations of benzene, and Figure 5 is the absorbance data diagram corresponding to the solutions with different concentrations.

It can be concluded from Figure 5 that the solubilization limit A of TMDAB to benzene is 0.2195mL, which is calculated by substituting the following formula:

$\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; 1000</span>}}{\mathrm{<span\; class="notranslate">\; V</span>}<span\; class="notranslate">\; \&times;</span>\mathrm{<span\; class="notranslate">\; c</span>}}$

Its compatibilization ability X is calculated to be 1322mL/mol, which reaches the limit at a lower concentration, indicating that this surfactant at a lower concentration can reach the critical micelle concentration, and a better dissolution effect can be achieved with a small amount , the oil can be dispersed into the aqueous solution at a relatively low concentration, and the solubilization effect is better.

Emulsifying properties of the product:

The emulsifying properties of hexadecylmethyldihydroxyethylammonium bromide (TMDAB) and commercially available surfactants EQ and D1821 were measured. The results are shown in Table 2. TMDAB has a very strong emulsifying ability. The turpentine-water and kerosene-water systems are better than the other two surfactants, but the benzene-water system is slightly inferior.

The emulsifying properties of table 2 surfactant

Embodiment 6: the influence of temperature of reaction on the conversion rate of N-methyldiethanolamine

Weigh 40.0g hexadecane bromide and 17.184g MDEA (N-methyldiethanolamine) into a flat-bottomed flask, stir with a mechanical stirrer, and react at a reaction temperature of 90°C, 100°C, 110°C, and 120°C respectively. The experiment was carried out under the condition that the molar ratio was 1.1:1, and the reaction time was 110min.

The experimental results are shown in Table 3 below:

The influence of table 3 reaction temperature on MDEA conversion rate

It can be seen from Table 3 that as the reaction temperature increases, the conversion rate of MDEA increases gradually, but the increase of the conversion rate of MDEA is not obvious after exceeding 110 °C. This is because the higher temperature is conducive to the nucleophilic addition of hexadecane bromide and MDEA, and accelerates the reaction to proceed in the positive direction. However, it can be seen from the color of the product that the color of the product deepens when the temperature exceeds the temperature. This is due to the generation of by-products and the oxidation of MDEA in the air, which increases the energy consumption at high temperature, so the optimum temperature for this reaction is 110 ° C.

Embodiment 7: The influence of reactant molar ratio on MDEA conversion rate

At a reaction temperature of 110°C, MDEA reacted with hexadecane bromide for 110 minutes. Respectively react under different ratios of n(bromohexadecane):n(MDEA) 0.9:1.0, 1.0:1.0, 1.1:1, 1.2:1.0. Samples were then taken to determine conversion. The results are shown in Table 4:

It can be seen from Table 4 that as the ratio of n (hexadecane bromide): n (MDEA) increases, the conversion rate of MDEA gradually increases. Due to the content of tertiary amine in the experimental titration reaction system, when MDEA is higher than The conversion rate is not high when the theoretical amount is added, because there is still residual MDEA after the reaction reaches equilibrium, but the conversion rate is not significantly improved when the molar ratio is higher than 1.1:1.0. In comparison, a slight excess of hexadecane bromide It can help the reaction to proceed in the positive direction.

Table 4, the influence of reactant molar ratio on MDEA conversion rate

Embodiment 8: the influence of time on conversion rate

The reaction was carried out under the condition that the reaction temperature was 110°C, n (bromohexadecane): n (MDEA) was 1.1:1, and the MDEA was measured at 15, 30, 45, 60, 75, 90, 105, and 120 min. Conversion rate. It can be seen from Figure 4 that the conversion rate of MDEA increases with the increase of the reaction time, and the conversion rate of MDEA gradually increases after the reaction time of 110 min, so the most suitable reaction time is selected as 110 min.

Embodiment 9: Optimizing process re-experiment

According to the results of single factor experiment, it is determined that the reaction temperature is 110°C, n(bromohexadecane):n(MDEA)=1.1:1, and the reaction time is 110min, and the experiment is repeated three times. The results are as follows: 5:

Table 5 optimized process repeated experiment results

It can be seen from Table 5 that the experiments were repeated three times under the optimized conditions, and the conversion rate of MDEA was above 96%. This condition has good reproducibility and can be used as the optimized process condition.

Claims (10)

1. a preparation method of cetyl methyl dihydroxyethyl ammonium bromide, is characterized in that comprising the steps: Weigh N-methyldiethanolamine and hexadecane bromide and place them in a three-necked flask equipped with a mechanical stirrer, a reflux condenser, and a thermometer, and heat in an oil bath for reaction; after fully reacting, use ethyl acetate and absolute ethanol to The crude product was recrystallized from the mixed solution, and bright white crystals were obtained by suction filtration, which was obtained after vacuum drying. 2. preparation method as claimed in claim 1, is characterized in that, the mol ratio of described hexadecane bromide and N-methyldiethanolamine is 0.5-3.5:1. 3. preparation method as claimed in claim 2 is characterized in that, the mol ratio of described hexadecane bromide and N-methyldiethanolamine is 0.8-1.5:1. 4. preparation method as claimed in claim 2 is characterized in that, the mol ratio of described hexadecane bromide and N-methyldiethanolamine is 1.1:1. 5. The preparation method according to claim 1, characterized in that, the reaction temperature is 80-150°C. 6. The preparation method according to claim 4, characterized in that, the reaction temperature is 110°C. 7. preparation method as claimed in claim 1 is characterized in that, described reaction time is 110min. 8. The preparation method according to claim 1, characterized in that, the number of times of said recrystallization is 3 times. 9. The preparation method according to claim 1, characterized in that, the vacuum drying temperature is 50°C. 10. The preparation method according to claim 1, characterized in that, in the mixed solution of ethyl acetate and absolute ethanol, the volume ratio of ethyl acetate and absolute ethanol is 1:1-10.

Images