CN110698364B - Method for synthesizing mono/dialkyl sodium benzenesulfonate - Google Patents

Abstract

The invention discloses a method for synthesizing mono/dialkyl benzene sulfonate, which uses ionic liquid to catalyze medium-chain alpha-olefin to synthesize alkylbenzene and sulfonate thereof and researches the surface performance of the alkylbenzene and the sulfonate. The invention firstly takes alpha-olefin and benzene as raw materials to carry out alkylation reaction in acidic ionic liquid, aiming at synthesizing various surfactant intermediates, and the obtained intermediates are taken as raw materials to carry out sulfonation by using chlorosulfonic acid and neutralization by using sodium hydroxide, thus finally obtaining various sodium alkyl benzene sulfonate surfactants. The surfactant obtained by the invention can obviously reduce the surface tension of water, and the emulsifying property and the wettability of the surfactant are obviously superior to those of sodium dodecyl benzene sulfonate.

Description

A kind of synthetic method of mono/dialkylbenzene sodium sulfonate

technical field

The invention relates to a method for synthesizing sodium mono/dialkylbenzene sulfonate, and belongs to the field of surfactant synthesis and application.

Background technique

Fischer-Tropsch synthesis (FTS) is one of the most efficient ways to utilize coal resources by converting coal-based syngas into clean liquid fuels. It is well known that alpha-olefins (C ₅ -C ₁₁ ) are present in high content in FTS products. However, these alpha-olefins are generally used as low value-added liquid fuels. Therefore, it is necessary and valuable to improve the high value-added utilization of α-olefins through various approaches.

Linear alkyl benzene sulfonates are important surfactants used in a wide range of industrial and consumer products. It is well known that their synthesis is usually by the alkylation of benzene by long-chain olefins (C ₁₀ -C ₁₄ ) over acidic catalysts such as HF and H ₂ SO ₄ . However, these catalysts also bring serious environmental problems, and the post-processing, separation and recovery of these catalysts is a tedious task. In recent years, acidic ionic liquids have been considered as greener catalysts and solvents. The properties of ionic liquids include their negligible vapor pressure, potential for recycling, compatibility with various organic compounds and organometallic catalysts, and ease of separation from reaction products. Using ionic liquids as catalysts for the alkylation of benzene to improve the conversion and selectivity of target products, many research results have been achieved.

The structure-activity relationship of monosubstituted long-chain alkylbenzene sulfonates has been extensively studied, but these studies have mainly focused on alkylbenzene sulfonates with different chain lengths and substituent positions. In the disubstituted and polysubstituted alkylbenzene sulfonates, most of the long-chain and short-chain alkyl groups are attached to the benzene ring. It was found that long-chain alkyl benzene sulfonates can significantly reduce the surface tension of water with a lower critical micelle concentration. Long-chain alkylbenzenes with chain length (C ₁₀ - C ₁₄ ) alpha-olefins are mainly derived from paraffin dehydrogenation technology in petroleum production. However, the depletion of crude oil reserves and rising crude oil prices have created an urgent need for new sources of alpha-olefin feedstocks.

SUMMARY OF THE INVENTION

The present invention aims to provide a method for synthesizing sodium mono/di-alkyl benzene sulfonate, utilizes ionic liquid to catalyze the preparation of sodium mono-/ di-alkyl benzene sulfonate, and aims to utilize the medium and long chains of C ₆ and C ₈ in Fischer-Tropsch synthesis Olefins. The ionic liquid catalyst used is mild and efficient, easy to separate from the product, and overcomes the shortcomings of traditional alkylation catalysts such as environmental pollution, strong toxicity and strong corrosiveness.

The invention uses benzene and medium and long-chain alpha-olefins as raw materials, ionic liquids as catalysts to synthesize alkylbenzene, and the alkylbenzene undergoes sulfonation and neutralization reactions to obtain the final product, sodium mono/dialkylbenzene sulfonate.

The invention provides a kind of synthetic method of mono/dialkyl benzene sodium sulfonate, comprising the following steps:

(1) Using α-olefin and benzene as raw materials, the alkylation reaction takes place in an acidic ionic liquid, and the yield of mono/di-alkylbenzene is controlled by controlling the ratio of benzene to olefin; At 8:1~14:1, for the synthesis of dialkylbenzene, the benzene-ene ratio is controlled at 1:2~1:8;

(2) carrying out sulfonation reaction of mono/dialkylbenzene and chlorosulfonic acid to obtain sulfonic acid;

(3) The purified mono/dialkylbenzene is neutralized with sodium hydroxide to obtain the final product mono/dialkylbenzene sodium sulfonate.

In the described synthesis step, the acid ionic liquid used is triethylamine hydrochloride-aluminum chloride (Et ₃ NHCl-AlCl ₃ ); the α-olefin used is any one of hexene and octene.

In the described synthesis step, the sulfonation temperature is controlled at 5-15° C., and the mass ratio of mono/dialkylbenzene to chlorosulfonic acid is 1:1.05～1:1.1.

In the described synthesis step, the mass percentage of sodium hydroxide is 10-30%, and the pH value after neutralization is 7-8.

The present invention provides the mono/di-alkylbenzene sodium sulfonate prepared by the above method;

The general formula of the monoalkylbenzene sodium sulfonate that above-mentioned synthetic method obtains is:

C _n -MSABS;

The general formula of the sodium dialkylbenzene sulfonate that above-mentioned synthetic method obtains is:

C _n -DSABS

where n=6 or 8.

Beneficial effects of the present invention:

(1) The present invention improves the high value-added utilization of α-olefin, the reaction product and the catalyst are easily separated, the experimental operation is simple, and the equipment requirements are low.

(2) The present invention can control the yield of mono/di-alkyl benzene by controlling the ratio of benzene to olefin, and finally can obtain sodium mono/di-alkyl benzene sulfonate with higher purity; compared with single-chain alkyl benzene sulfonate , the double-chain alkylbenzene sulfonate has a better ability to reduce the surface tension of water due to the increase in the number of hydrophobic chains on the benzene ring.

(3) Compared with commercial sodium dodecylbenzenesulfonate, the sodium dialkylbenzene sulfonate obtained in the present invention reduces the surface tension of water, and in addition, has better emulsifying performance and wetting performance.

Description of drawings

Fig. 1 is the surface tension diagram of the sodium alkylbenzene sulfonate surfactant synthesized in Example 1～Example 10.

Fig. 2 is the emulsifying performance of the sodium alkylbenzene sulfonate surfactant synthesized in Example 1～Example 10.

Detailed ways

The present invention is further illustrated by the following examples, but is not limited to the following examples.

Example 1:

A kind of synthesis of sodium monoalkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.8 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.6 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene and 1-hexene of 14:1, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the required 1-hexene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product is taken, washed with water, and then distilled under reduced pressure to obtain monohexylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of 1-hexene was 100%, and the selectivity of monohexylbenzene was 94%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.05. After 2 h of reaction, the reaction product was neutralized to pH = 7 with 20 % (w/w) sodium hydroxide solution, then extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium monohexylbenzenesulfonate (C ₆ -MSABS) . The active content was determined to be 94 % by two-phase titration.

Example 2

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.8 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.6 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene and 1-hexene of 1:6, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the required 1-hexene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain dihexylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 100%, and the selectivity of dihexylbenzene was 52%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.1. After 2 h of reaction, the reaction product was neutralized to pH = 7 with 10% (w/w) sodium hydroxide solution, then extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium bis-hexylbenzenesulfonate (C ₆ -DSABS) . The active content was determined to be 95 % by two-phase titration.

Example 3

A kind of synthesis of sodium monoalkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.5 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.9 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene:1-octene of 12:1, firstly add benzene to the ionic liquid, stir at 60 °C, and then slowly add the required 1-octene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product is taken, washed with water, and then distilled under reduced pressure to obtain monooctylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of 1-octene was 100%, and the selectivity of monooctylbenzene was 93%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.05. After 2 h of reaction, the reaction product was neutralized to pH=7 with 30% (w/w) sodium hydroxide solution, extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium monooctylbenzenesulfonate (C ₈ - MSABS). The active content was determined to be 96 % by two-phase titration.

Example 4

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.8 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.6 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene: 1-octene of 1:4, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the required 1-octene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain bis-octylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 100%, and the selectivity of bis-octylbenzene was 56%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.1. After reacting for 2 h, the reaction product was neutralized to pH=7 with 20% (w/w) sodium hydroxide solution, extracted and purified with ethanol and petroleum ether, and dried to obtain sodium bis-octylbenzenesulfonate (C ₈ - DSABS). The active content was determined to be 94 % by two-phase titration.

Example 5

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.5 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.9 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene and 1-hexene of 1:2, benzene was firstly added to the ionic liquid, and then the desired 1-hexene was slowly added dropwise under stirring at 60 °C. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain dihexylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 95%, and the selectivity of dihexylbenzene was 42%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100-mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.05. After 2 h of reaction, the reaction product was neutralized to pH=7 with 30% (w/w) sodium hydroxide solution, extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium bis-hexylbenzenesulfonate (C ₆ -DSABS) . The active content was determined to be 96 % by two-phase titration.

Example 6

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.5 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.9 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene:1-octene is 1:2, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the required 1-octene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain bis-octylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 97%, and the selectivity of bis-octylbenzene was 56%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.1. After reacting for 2 h, the reaction product was neutralized to pH=7 with 20% (w/w) sodium hydroxide solution, extracted and purified with ethanol and petroleum ether, and dried to obtain sodium bis-octylbenzenesulfonate (C ₈ - DSABS). The active content was determined to be 96 % by two-phase titration.

Example 7

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.8 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.6 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene:1-hexene of 1:8, firstly add benzene to the ionic liquid, stir at 60 °C, and then slowly add the desired 1-hexene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain dihexylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 100%, and the selectivity of dihexylbenzene was 52%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.1. After 2 h of reaction, the reaction product was neutralized to pH = 7 with 10% (w/w) sodium hydroxide solution, then extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium bis-hexylbenzenesulfonate (C ₆ -DSABS) . The active content was determined to be 94% by two-phase titration.

Example 8

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.5 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.9 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene:1-octene of 1:6, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the desired 1-octene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain bis-octylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 100%, and the selectivity of bis-octylbenzene was 65%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.05. After 2 h of reaction, the reaction product was neutralized to pH=7 with 30% (w/w) sodium hydroxide solution, extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium bis-octylbenzenesulfonate (C ₈ - DSABS). The active content was determined to be 98 % by two-phase titration.

Example 9

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.8 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.6 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene: 1-hexene of 1:4, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the desired 1-hexene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain dihexylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 100%, and the selectivity of dihexylbenzene was 52%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.1. After 2 h of reaction, the reaction product was neutralized to pH=7 with 30% (w/w) sodium hydroxide solution, extracted and purified with ethanol and petroleum ether, respectively, and dried to obtain sodium bis-hexylbenzenesulfonate (C ₆ -DSABS) . The active content was determined to be 95 % by two-phase titration.

Example 10

A kind of synthesis of sodium dialkylbenzene sulfonate in the present embodiment, described synthesis step comprises the following aspects:

A fixed amount of triethylamine hydrochloride (1.8 mmol), n-decane (5.34 g), and anhydrous aluminum chloride (3.6 mmol) were added to a 100 mL three-necked flask equipped with a reflux condenser, under argon atmosphere for 60 ℃ and stirred for 1 h. After stopping stirring, the mixture was separated into layers, the upper layer was n-decane, and the lower layer was an ionic liquid catalyst composed of [Et ₃ NH ⁺ ][Al ₂ Cl ₇ ^- ]. According to the molar ratio of benzene: 1-octene of 1:8, first add benzene to the ionic liquid, stir at 60 °C, and then slowly add the desired 1-octene dropwise. After the alkylation reaction is completed, the mixture is cooled to room temperature and then separated into layers, the upper layer is n-decane, alkylbenzene product and unreacted material, and the lower layer is ionic liquid catalyst. The upper layer liquid product was taken, washed with water, and then distilled under reduced pressure to obtain bis-octylbenzene.

The product was analyzed by gas chromatograph and showed that the conversion rate of benzene was 100%, and the selectivity of bis-octylbenzene was 65%.

Using chlorosulfonic acid as the sulfonating agent, the sulfonation reaction of alkylbenzene was carried out in a 100 mL flask equipped with a magnetic stirring bar. The molar ratio of alkylbenzene to chlorosulfonic acid was fixed at 1:1.05. After 2 h of reaction, the reaction product was neutralized to pH=7 with 10% (w/w) sodium hydroxide solution, then extracted and purified with ethanol and petroleum ether respectively, and dried to obtain sodium bis-octylbenzenesulfonate (C ₈ - DSABS). The active content was determined to be 97 % by two-phase titration.

The surface tension of the products obtained in the above examples was measured using the Kruss K100 tensiometer hanging piece method.

Table 1 shows the surface activity parameters of the sodium alkyl benzene sulfonate surfactants synthesized in Examples 1 to 10. The parameter calculation method is as follows:

Table 1

It can be seen from Figure 1 and Table 1 that with the increase of the concentration, the surface tension shows a downward trend, and after exceeding the CMC, the surface tension value tends to be stable. However, _C6 -MSABS and C8- _MSABS did not show CMC dots, which may be due to the too short hydrophobic chain, at this concentration, aggregation at the air-water interface fails to form micelles. Comparing SDBS, C ₆ -DSABS and C ₈ -DSABS, it is found that the hydrophobic effect is enhanced with the increase of the alkyl chain length, which makes the alkyl chain easy to migrate to the air-water surface, the surface tension and the critical glue The beam concentration is significantly reduced.

Figure 2 shows the emulsifying properties of the sodium alkyl benzene sulfonate surfactants synthesized in Examples 1 to 10. The specific testing process is as follows: the emulsifying properties are measured by the water separation time method. Using liquid paraffin (40 mL) as the oil phase, an aqueous solution containing 1.0 g L of sodium ^alkylbenzene sulfonate surfactant (40 mL) was poured into 100 mL of the oil phase. Invert the stoppered graduated cylinder 5 times and let stand for 1 minute. The experiment was performed 5 times and the separation time of 10 mL of water was recorded to characterize the emulsifying power.

Figure 2 shows the relationship between water separation and time, and the emulsification performance is qualitatively evaluated according to the time required to separate 10 mL of the water phase; the longer the separation time, the higher the emulsification power. The results showed that the emulsifying ability of C ₈ -DSABS to liquid paraffin was enhanced compared with other sodium alkyl benzene sulfonates. The emulsifying ability of C ₆ -DSABS is slightly better than that of SDBS. The stability of the emulsion is related to the interfacial properties of the adsorption membrane. Generally, the longer the hydrophobic chain, the larger the interfacial expansion modulus, the greater the adsorption of the surfactant at the interface, the stronger the formed interfacial film, and the more stable the formed emulsion.

Table 2 shows the wetting properties of the sodium alkyl benzene sulfonate surfactants synthesized in Examples 1 to 10, and the measurement standard refers to HG/T 2575-94.

Table 2

The settling times of the round canvas pieces in the three aqueous sodium alkylbenzene sulfonate solutions are shown in Table 2. As can be seen from the table, the wettability of the three sodium alkylbenzene sulfonates increases with increasing surfactant concentration. When the concentration is 0.5 g L ^-1 , the sedimentation time of the circular canvas sheet in the C ₆ -DSABS and SDBS aqueous solutions increases rapidly, and when the concentration is 0.25 g L ^-1 , the sedimentation time of the circular canvas sheet in the C ₈ -DSABS aqueous solution Time increases rapidly. Because the critical micelle concentration of _C6 -DSABS and SDBS is ~0.5 g L- ¹ , while the critical micelle concentration of C8- _DSABS is ~0.25 g L ^-1 . The results show that the wettability of the fabric is excellent when the surfactant concentration is higher than the critical micelle concentration. At a concentration of 1 g L ^-1 , the wettability of three sodium alkylbenzene sulfonates was compared, and it was found that C ₈ -DSABS was the most ideal, followed by C ₆ -DSABS, and then SDBS.

Claims (2)

1. A method for synthesizing sodium dialkyl benzene sulfonate is characterized in that: benzene and medium-long chain alpha-olefin are used as raw materials, ionic liquid is used as a catalyst to synthesize alkylbenzene, and the alkylbenzene is subjected to sulfonation and neutralization reaction to obtain a final product, namely sodium dialkyl benzenesulfonate;

the medium-long chain alpha-olefin is hexene or octene;

the synthesis method of the sodium dialkyl benzene sulfonate comprises the following steps:

(1) taking alpha-olefin and benzene as raw materials, carrying out alkylation reaction in an acidic ionic liquid, and controlling the yield of dialkyl benzene by controlling the benzene-olefin ratio; the benzene-olefin ratio is controlled to be 1: 2-1: 8;

(2) carrying out sulfonation reaction on dialkyl benzene and chlorosulfonic acid under the condition of no need of a solvent to obtain dialkyl benzene sulfonic acid;

(3) neutralizing the dialkyl benzene sulfonic acid and sodium hydroxide, and extracting and purifying to obtain a final product, namely the dialkyl benzene sulfonic acid sodium salt;

the temperature of the alkylation reaction in the step (1) is 60 ℃;

the acidic ionic liquid in the step (1) is triethylamine hydrochloride-aluminum chloride;

in the step (2), the sulfonation temperature is controlled to be 5-15 ℃, and the mass ratio of the dialkyl benzene to the chlorosulfonic acid is 1: 1.05-1: 1.1.

2. The method for synthesizing sodium dialkylbenzenesulfonate according to claim 1, characterized in that: the mass percent of the sodium hydroxide is 10-30%, and the pH value after neutralization is 7-8.

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