WO2013170430A1

WO2013170430A1 - Process for synthesizing acetyl citrate

Info

Publication number: WO2013170430A1
Application number: PCT/CN2012/075480
Authority: WO
Inventors: 郭凯; 方正; 欧阳平凯; 周扬志; 韦萍; 姜岷; 徐虹
Original assignee: 南京工业大学
Priority date: 2012-05-14
Filing date: 2012-05-14
Publication date: 2013-11-21

Abstract

A process for synthesizing acetyl citrate catalytically, comprising the following steps: 1) preparation of a catalyst: dipping woody active carbon into an acid solution, mixing, loading and fixing at room temperature, filtrating and drying to obtain the catalyst loaded and fixed with active carbon, 2) synthesis of citrate: into a reactor, adding (hydration) citric acid and alcohol, and a composite catalyst composed of the catalyst loaded and fixed with active carbon from step 1) and one of acids selected from H2SO4, benzene sulfonic acid, p-toluenesulfonic acid, methanesulfonic acid, NaHSO4 or trifluoromethanesulfonic acid, carrying out esterification at 130℃-160℃ filtrating and dealcoholizing the reaction mixture to obtain the crude critrate; 3) synthesis of acetyl citrate: adding acid anhydride into crude citrate from step 2), acylating at 60℃-90℃, and post treating the reaction product to obtain the end product of acetyl citrate. The composite catalyst is used in the esterification and acylation reaction of the present invention, which results in less amount of catalyst, high efficiency, good product quality, compact and integrated process, and therefore, the process is suitable for industrialized application.

Description

Process for synthesizing acylated citrate ester

The invention relates to a method for synthesizing a green plasticizer acylated citrate ester, belonging to the field of chemical synthesis process. Background technique

Traditional plasticizer phthalates may cause carcinogenicity and have been restricted by legislation abroad. Citric acid ester and acylated citrate ester have been approved by the US Food and Drug Administration (FDA) as a "green" environmentally friendly plasticizer. They are non-toxic, odorless, mildew resistant, plasticized, cold resistant and light resistant. It is widely used in food packaging, medical products, children's toys, etc., and is the first choice for replacing phthalate plasticizers.

At present, citrate and acylated citrate have huge vacancies in the domestic market. The traditional method of synthesis is concentrated sulfuric acid and the like. Although the homogeneous system has good catalytic effect, it also has obvious disadvantages: sulfuric acid easily enters wastewater, vice There are many products, the equipment is seriously corroded, a large amount of lye is neutralized and washed, and the post-treatment is complicated. The "three wastes" have large emissions and pollute the environment. The preparation process of the acylated citrate ester in the prior art is firstly prepared by using citric acid and an alcohol as raw materials, esterification, neutralization, water washing, dealcoholation and water, and decolorization under the action of a catalyst; The catalyst is added, and the acylated citrate is obtained by acylation, deacidification, neutralization, water washing, dehydration and decolorization. The disadvantages of this process are: complicated process, long production cycle, large product loss, large equipment investment, large emissions of “three wastes” and environmental pollution.

Therefore, in order to overcome the shortcomings of homogeneous system catalysts and processes, the study of green catalysts and simple processes is of great significance for the development of environmentally friendly plasticizers for the acylation of citrate esters.

CN200710132445.5 Disclosed is a method for synthesizing acylated tributyl citrate by using an ionic catalyst, comprising: Step 1: adding citric acid, n-butanol and sodium hydrogen sulfate monohydrate in a reaction kettle, and refluxing under stirring, After cooling, the catalyst is recovered by filtration, neutralized by adding an alkaline solution to the filtrate, washed with water until neutral, and then normal-pressure distillation is used to recover n-butanol, and the residual water is distilled off under reduced pressure to obtain crude tributyl citrate, and then activated carbon is added. Decolorization treatment of alumina composite decolorizer to obtain finished product of tributyl citrate; Step 2: adding a finished product of tributyl citrate, an acid anhydride and sodium hydrogen sulfate monohydrate in the reaction vessel, and reacting at a temperature of 50 to 90 ° C under stirring ~3.0 hours cooling filtration to recover the catalyst; adding neutral solution to the filtrate, and then washing to the middle The aqueous phase was separated, and then n-butyl acetate was recovered by distillation under reduced pressure to obtain an acylated tributyl citrate. In the method, the process of catalyst separation, neutralization, water washing and decolorization is still needed in the TBC preparation process, the process flow is complicated, and the product yield is low.

CN201010583409.2, CN200610024372.3, CN200810195075.4 and CN200510030100.X etc. disclose a method for heterogeneously catalyzing the preparation of tributyl citrate, wherein the catalyst synthesis process is complicated, after esterification reaction, filtration, water (alkali) Tributyl citrate can be obtained by post-treatment such as washing or distillation. In order to obtain ATBC, the obtained TBC is further acylated under the catalytic action of concentrated sulfuric acid, p-toluenesulfonic acid, etc., the process flow is long, the operation is complicated, and the product yield is low.

Summary of the invention

The object of the present invention is to provide a process for synthesizing acylated citrate ester, which can overcome the disadvantages of the prior art acylated citrate ester preparation method, such as complicated process, long production cycle, large product loss, and "three wastes". The composite catalyst comprising activated carbon supported catalyst has simple preparation, easy separation and recovery, small catalyst dosage, high catalytic efficiency, mild reaction condition and good product quality index; and the invention adopts integrated process, eliminating Refined citrate ester link.

The technical solutions adopted by the present invention are as follows:

A process for synthesizing an acylated citrate ester, comprising the steps of:

1) Preparation of activated carbon supported catalyst

A certain amount of wood activated carbon is immersed in sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid or sodium hydrogen sulfate solution, and is fixed under normal temperature stirring condition. The catalyst is filtered and dried to constant weight to obtain activated carbon supported catalyst. (C-CAT);

2) Citric acid ester synthesis

Adding (hydrating) citric acid and alcohol to the reactor, adding the activated carbon supported catalyst prepared in the step 1) to the compound catalyst composed of the non-supporting catalyst, wherein the non-supporting catalyst is selected from the group consisting of H ₂ S0 ₄ and benzenesulfonate. Acid, p-toluenesulfonic acid, methanesulfonic acid, NaHS0 ₄ or trifluoromethanesulfonic acid, stirred at 130 ° C ~ 160 ° C for 3 h ~ 6 h for esterification reaction, filtered to recover alcohol, to obtain crude citric acid ester ;

3) Synthesis of acylated citrate

Adding an acid anhydride to the crude citric acid ester obtained in the step 2), reacting at 60 ° C to 90 ° C for 0.5 h to 3.5 h, filtering the reaction liquid, filtering the filtrate, recovering the acid anhydride or acid, and post-treating to obtain an acylated lemon. The finished product of the ester. In the step 1), the woody activated carbon is preferably activated carbon for decolorization of sugar.

In step 1), the immobilization time is 20 h to 60 h, preferably 25 to 50 h.

In the step 1), the catalyst drying temperature is from 100 ° C to 150 ° C, preferably from 120 ° C to 140 ° C.

Step 1) The concentration of sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid or sodium hydrogen sulfate solution is preferably 20 ~ 50, and the mass ratio of wood activated carbon is 5~20:1. The prepared activated carbon supported catalyst can be measured by a weight gain method or a titration method.

The catalyst used in the present invention is a compound catalyst of a supported catalyst and a non-supported catalyst, and the non-support catalyst includes H ₂ S0 ₄ , p-toluenesulfonic acid (PTSA), methanesulfonic acid (MSA), methanesulfonic acid (PSA). , NaHS0 ₄ or trifluoromethanesulfonic acid, activated carbon supported catalysts include CH ₂ S0 ₄ , C-PTSA, C-MSA, C-PSA or C-NaHS0 ₄ , non-supported catalyst and supported catalyst are mixed in a certain ratio .

Non-co-supported catalysts have many disadvantages such as excessive by-products, serious equipment corrosion or large amount of post-treatment "three wastes". In order to improve product purity, it needs to be neutralized and washed after esterification, and the citrate ester is refined. The acylation reaction is carried out. However, the supported catalyst has the disadvantages of low solid storage rate, large dosage and long reaction time. The direct catalyzed acylation reaction has certain by-products, which is not conducive to further improvement of product purity. The invention adopts a compounding catalyst, and removes the supported catalyst after the esterification reaction, and the separation and recovery are simple, and the acylation reaction is carried out by using a non-supporting catalyst, and the esterification reaction product does not need to be neutralized and then added with a catalyst, thereby reducing the amount of the catalyst and The amount of "three wastes" can increase the purity of the target product.

The complex catalyst preferably uses CH ₂ SO _{4 in} combination with PTSA, MSA, PSA or trifluoromethanesulfonic acid. See Table 1 for a comparison of the use of a supported or unsupported catalyst alone or with a compound catalyst:

Table 1 Comparison of catalysts used alone and catalysts used in combination

C-MSA has low solid load rate, high dosage and high cost

C-NaHS0 ₄ low solid load rate, large dosage

Compound catalyst

PTSA, PSA, MSA and so it avoids the use of complex and costly when PTSA, PSA, MSA, either singly, CH ₂ S0 ₄ and the like after the compound used and other shortcomings waste treatment; and avoid only the amount of CH ₂ S0 _4, etc. Large, long reaction time, the existence of by-products, the disadvantage of equipment corrosion. The amount of the compound catalyst is preferably 0.2% to 2.0%, preferably 0.3 to 1.0, of the mass of the (hydrated) citric acid; wherein the amount of the non-supporting catalyst is 0.05% to 1.0% of the mass of the (hydrated) citric acid, preferably 0· 05%~0.5%.

The alcohol is an aliphatic linear or branched alcohol having a total carbon number of 2 to 13 in the molecule.

The molar ratio of the (hydrated) citric acid to the alcohol is 1:3 to 7, preferably 1 to 3.5 to 5.

The acid anhydride is acetic anhydride, propionic anhydride or butyric anhydride, preferably acetic anhydride.

The molar ratio of the (hydrated) citric acid to the acid anhydride is 1: 1 to 2, preferably 1 : 1.1 to 1.5.

The method of the invention adopts an integrated synthesis method, that is, the crude citrate ester obtained by the step 2) esterification reaction product only by dealcoholation, and the acylate ester is directly acylated to synthesize the acylated citrate ester; the acylation reaction does not need to be supplemented. catalyst.

In step 3), the post treatment includes alkali neutralization, water washing and dehydration. Depending on the specific situation, when the product color requirement is further improved (10#), decolorization of activated carbon may also be added.

The process for synthesizing acylated citrate ester of the invention has the characteristics of being both efficient and environmentally friendly. Specifically, the following beneficial effects are included:

(1) The esterification and acetylation reaction of the method of the present invention employs a compound catalyst and is added once during the reaction. The use of a catalyst-supporting catalyst and a non-support catalyst catalyst can reduce the amount of the catalyst and have a good catalytic effect.

(2) The activated carbon supported catalyst used in the present invention has both catalytic and decolorizing effects, and the citrate product does not need to be decolored.

(3) The integrated process of the invention eliminates the step of purifying the citrate ester in the conventional process, and directly performs the acylation reaction after dealcoholation, thereby reducing the "three wastes", reducing the cost, and improving the product yield.

(4) The reaction conditions are mild, the energy consumption is reduced, the equipment corrosion is obviously reduced, the production cycle is short, and the three wastes are discharged. Put less.

(5) The method of the invention has high esterification rate (98.5%), good product quality, acylation citrate purity 99.5%, color 15# (platinum-cobalt).

The invention is described in detail below with reference to specific embodiments. The scope of the present invention is not limited to the specific embodiments, but is defined by the claims. detailed description

Example 1

The preparation of activated carbon supported sulfuric acid catalyst adopts the following methods:

Soak 50.0 g of woody activated carbon in a certain amount of solution listed in Table 1. Stir at room temperature for 20h~60h. The catalyst is filtered and dried at 12CTC to constant weight to obtain activated carbon supported catalyst (C-CAT). The method calculates the solid loading rate (wt%) of the catalyst.

The preparation and immobilization rate of activated carbon supported catalyst (C-CAT) are shown in Table 2 below:

Table 2 Solid-state catalyst immobilization rate

Example 2

An acetyl tributyl citrate process using an integrated approach comprising the following steps:

1) Tributyl citrate (TBC) synthesis

Add 21.0kg (100mol) of citric acid monohydrate, 29.7kg (400mol) of n-butanol, and 20.0g of catalyst CH ₂ S0 _{4 to} the reaction flask equipped with a stirrer, thermometer, water separator and condenser. 0.33%) and PTSA63.0g (0.3% of hydrated citric acid mass), stirred at 130 ° C ~ 160 ° C for 3.0 h ~ 6.0 h, synthesize TBC, according to GB 1668-81 acid value, control The acid value was 3 mgKOH/g, and the product was filtered to remove the alcohol to obtain a crude TBC. 2) Acetyl tributyl citrate (ATBC) synthesis

Add 12.3 kg (120.0 mol) of acetic anhydride to the crude TBC (35.5 kg) prepared in step 1), and react at 70 ° C for 1.5 h to synthesize ATBC and add water (the amount of water added is equal to or slightly larger than unreacted acetic anhydride). The amount required for complete hydrolysis), acetic acid is recovered after hydrolysis of acetic anhydride, neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain an ATBC finished product.

The obtained ATBC finished product has a purity of 99.6%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 3

A process for propionyl tributyl citrate, using an integrated method, comprising the following steps:

1) A crude tributyl citrate was synthesized in the same manner as in Example 2.

2) Synthesis of propionyl tributyl citrate

To the crude TBC (35.5 kg) obtained in the step 1), 15.6 kg (120 mol) of propionic anhydride was added, and the reaction was carried out at 70 ° C for 1.5 h to synthesize propanyl tributyl citrate, and hydrolyzed propionic anhydride was added to recover propionic acid. It is neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of propionyl tributyl citrate.

The prepared product of propionyl tributyl citrate has a purity of 99.6%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 4

A process for butyryl tributyl citrate, using an integrated method, comprising the following steps:

1) A crude tributyl citrate was synthesized in the same manner as in Example 2.

2) Synthesis of butyryl tributyl citrate

To the crude TBC (35.5 kg) obtained in the step 1), 19.0 kg (120 mol) of butyric anhydride was added, and the reaction was carried out at 70 ° C for 1.5 h to synthesize butyryl tributyl citrate, and hydrolyzed butyric acid was added to recover butyric acid. It is neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of butyryl citrate tributyl citrate.

The obtained product of butyryl tributyl citrate has a purity of 99.6%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 5 A process for synthesizing acetyl tributyl citrate using an integrated method comprising the following steps:

1) Synthesis of tributyl citrate (TBC)

Add 21.0kg (100mol) of citric acid monohydrate, 29.7kg (400mol) of n-butanol, and 20.0g of catalyst CH ₂ S0 _{4 to} the reaction flask equipped with a stirrer, thermometer, water separator and condenser. 0.33%) and 42.0 g of benzenesulfonic acid (0.2% of the mass of citric acid hydrate), stirring at 130 ° C ~ 160 ° C for 3.0 h ~ 6.0 h, synthesizing TBC, measuring the acid value according to GB 1668-81, The acid value of the control is 3 mgKOH/g, and the product is filtered to remove the alcohol, and the crude product is obtained.

2) Acetyl tributyl citrate (ATBC) synthesis

To the crude TBC (35.5 kg) obtained in the step 1), 12.3 kg (120.0 mol) of acetic anhydride was added, and the reaction was carried out at 70 ° C for 1.5 h to synthesize ATBC, and acetic acid was hydrolyzed with water to recover acetic acid, and 5% sodium carbonate was used. The liquid is neutralized, washed, dehydrated, and the ATBC finished product is obtained.

The obtained ATBC finished product has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 6

1) A crude tributyl citrate was synthesized in the same manner as in Example 5.

2) Synthesis of propionyl tributyl citrate

The prepared product of propionyl tributyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 7

1) A crude tributyl citrate was synthesized in the same manner as in Example 5.

2) Synthesis of butyryl tributyl citrate

Add 19.0 kg (120 mol) of butyric anhydride to the crude TBC (35.5 kg) prepared in step 1). After reacting at 70 ° C for 1.5 h, synthesize butyryl tributyl citrate, and then hydrolyzing butyric acid to recover butyric acid, neutralize with 5% sodium carbonate lye, wash with water, and dehydrate to obtain tributyl butyl citrate. .

The prepared product of butyryl tributyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 8

A process for synthesizing acetyl tributyl citrate using an integrated method comprising the following steps:

1) Synthesis of tributyl citrate (TBC)

Add 21.0kg (100mol) of citric acid monohydrate, 29.7kg (400mol) of n-butanol, and 20.0g of catalyst CH ₂ S0 _{4 to} the reaction flask equipped with a stirrer, thermometer, water separator and condenser. 0.33%) and 10.5 g of trifluoromethanesulfonic acid (0.05% of citric acid hydrate), stirred at 130 ° C ~ 160 ° C for 3.0 h ~ 6.0 h, synthesized TBC, measured acid according to GB 1668-81 The value is controlled by an acid value of 3 mgKOH/g, and the product is filtered to remove the alcohol to obtain a crude TBC.

2) Acetyl tributyl citrate (ATBC) synthesis

To the crude TBC (35.5 kg) obtained in the step 1), 12.3 kg (120.0 mol) of acetic anhydride was added, and the reaction was carried out at 70 ° C for 1.0 h to synthesize ATBC, and acetic acid was hydrolyzed with water to recover acetic acid, and 5% sodium carbonate was used. The liquid is neutralized, washed, dehydrated, and the ATBC finished product is obtained.

The obtained ATBC finished product has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 9

A method for synthesizing propionyl tributyl citrate using an integrated method comprising the following steps:

1) Synthesis of tributyl citrate (TBC) in the same manner as in Example 8;

2) Synthesis of propionyl tributyl citrate

The prepared propanyl tributyl citrate product has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. A method for synthesizing butyryl tributyl citrate, using an integrated method comprising the following steps:

1) Synthesis of tributyl citrate (TBC) in the same manner as in Example 8;

2) Synthesis of butyryl tributyl citrate

The prepared product of butyryl tributyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 11

A process for synthesizing acylated citrate esters using an integrated process comprising the following steps:

1) Synthesis of tributyl citrate (TBC)

Add 21.0kg (100mol) of citric acid monohydrate, 29.7kg (400mol) of n-butanol, and 20.0g of catalyst CH ₂ S0 _{4 to} the reaction flask equipped with a stirrer, thermometer, water separator and condenser. 0.33%) and 31.5g of methanesulfonic acid (0.15% of the mass of hydrated citric acid, the total amount of catalyst accounts for 0.48% of the mass of citric acid monohydrate), and the reaction is stirred at 130 ° C ~ 160 ° C for 3.0 h ~ 6.0 h , TBC is synthesized, the acid value is measured according to GB 1668-81, the acid value is controlled at 3 mgKOH/g, and the product is filtered to remove the alcohol, and the TBC is coarse.

Π

Hey.

2) Acetyl tributyl citrate (ATBC) synthesis

The obtained ATBC finished product has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 12

A method for synthesizing propionyl tributyl citrate using an integrated method comprising the following steps: 1) Synthesis of tributyl citrate (TBC) in substantially the same manner as in Example 11, except that C ₂ PTSA was substituted for CH ₂ S0 ₄ ;

2) Synthesis of propionyl tributyl citrate

The prepared product of propionyl tributyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 13

A method for synthesizing butyryl tributyl citrate, using an integrated method comprising the following steps:

1) Synthesis of tributyl citrate (TBC) in substantially the same manner as in Example 11, except that C-PSA was substituted for CH ₂ S0 ₄ ;

2) Synthesis of butyryl tributyl citrate

The prepared product of butyryl tributyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 14

A process for synthesizing acetyl triisoamyl citrate adopts an integrated method comprising the following steps: 1) Synthesis of triisoamyl citrate

Add 21.0kg (100mol) of citric acid monohydrate, 35.3kg (400mol) of isoamyl alcohol, and 70.0g of CH ₂ S0 _{4 to} the reaction flask equipped with a stirrer, thermometer, water separator and condenser. 0.33%) and p-toluenesulfonic acid 63.0g (0.3% of the mass of hydrated citric acid, the total amount of catalyst accounts for 0.63% of the mass of citric acid monohydrate), and the reaction is stirred at 130 ° C ~ 160 ° C for 3.0 h ~ 6.0 h , Synthesis of triisoamyl citrate, according to GB 1668-81 acid value, medium control acid value of 3 mg KOH / g, the product is filtered to remove the alcohol, the crude triisoamyl citrate. 2) Synthesis of acetyl triisoamyl citrate

To the crude product of triisoamyl citrate prepared in step 1) (39.4 kg), 12.3 kg (120.0 mol) of acetic anhydride was added, and reacted at 70 ° C for 1.5 h to synthesize acetyl triisoamyl citrate and hydrolyze B. After the acid anhydride is recovered, the acetic acid is neutralized, neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of acetyl triisoamyl citrate.

The obtained product of acetyl triisoamyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 15

A method for synthesizing propionyl triisoamyl citrate, using an integrated method comprising the following steps:

1) Synthesis of triisoamyl citrate in substantially the same manner as in Example 14, except that C ₂ -MSA was substituted for CH ₂ S0 ₄ ;

2) Synthesis of propionyl triisoamyl citrate

To the crude triisoamyl citrate (39.4 kg) prepared in the step 1), 15.6 kg (120 mol) of propionic anhydride was added, and reacted at 75 ° C for 1.5 h to synthesize propionyl triisoamyl citrate, and hydrolyzed acid anhydride was added. After the propionic acid is recovered, it is neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of propionyl triisoamyl citrate.

The prepared product of propionyl triisoamyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 16

A method for synthesizing butyric acid triisoamyl citrate, using an integrated method comprising the following steps:

1) Synthesis of triisoamyl citrate in substantially the same manner as in Example 14, except that C-NaHS0 _{4 was} substituted for CH ₂ S0 ₄ ;

2) Synthesis of butyric acid triisoamyl citrate

To the crude triisoamyl citrate (39.4 kg) prepared in the step 1), 19.0 kg (120 mol) of butyric anhydride was added, and reacted at 75 ° C for 1.5 h to synthesize triisooctyl citrate citrate and hydrolyzed with water. After the recovery of butyric acid, it is neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of butyryl citrate triisoamyl pentoxide.

The obtained product of butyryl triisoamyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 17

A process for synthesizing acetyl triisooctyl citrate using an integrated method comprising the following steps:

1) Synthesis of triisooctyl citrate

Add 21.0kg (100mol) of citric acid monohydrate, 52.1kg (400mol) of isooctanol, and CH ₂ S0 ₄ 21. Og to the reaction flask equipped with a stirrer, thermometer, water separator and condenser. 0.1%) and benzenesulfonic _{42 .0g} (- 0.2% by mass of hydrated citric acid, 0.30% by mass of the total amount of citric acid monohydrate catalyst) was stirred at 130 ° C ~ 160 ° C reaction 3.0h ~ 6.0 h, synthesis of triisooctyl citrate, according to GB 1668-81 acid value, medium control acid value of 3mgKOH / g, the product is filtered to remove the alcohol, the crude triisooctyl citrate.

2) Synthesis of acetyl triisooctyl citrate

To the crude product of triisooctyl citrate prepared in the step 1), 12.3 kg (120.0 mol) of acetic anhydride was added, and the reaction was carried out at 70 ° C for 1.5 h to synthesize acetyl triisooctyl citrate, and the acetic acid was recovered by adding water to hydrolyze the acid anhydride. It is neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of acetyl triisooctyl citrate.

The obtained product of acetyl triisooctyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 18

A method for synthesizing triisooctyl propionate citrate using an integrated method comprising the following steps:

1) Synthesis of triisooctyl citrate in substantially the same manner as in Example 17, except that C ₂ -MSA was substituted for CH ₂ S0 ₄ ;

2) Synthesis of propionyl triisooctyl citrate

Adding 15.6 kg (120 mol) of propionic anhydride to the crude triisooctyl citrate (39.4 kg) prepared in the step 1), and reacting at 75 ° C for 1.5 h to synthesize propionyl triisooctyl citrate, hydrolyzed with water. After the acid anhydride, the propionic acid is recovered, neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of propionyl triisooctyl citrate.

The obtained product of triisooctyl propionyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Example 19

A method for synthesizing triisooctyl citrate citrate using an integrated method comprising the following steps: 1) Synthesis of triisooctyl citrate in substantially the same manner as in Example 17, except that NaHS0 _{4 was} used instead of benzenesulfonic acid;

2) Synthesis of butyric acid triisooctyl citrate

To the crude triisooctyl citrate (39.4 kg) prepared in the step 1), 19.0 kg (120 mol) of butyric anhydride was added, and reacted at 75 ° C for 1.5 h to synthesize triisooctyl citrate citrate and hydrolyzed with water. After the recovery of butyric acid, it is neutralized with 5% sodium carbonate lye, washed with water, and dehydrated to obtain a finished product of butyryl citrate triisooctyl citrate.

The prepared product of butyryl triisooctyl citrate has a purity of 99.5%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%. Comparative example 1

1) Synthesis of tributyl citrate (TBC)

To a reaction flask equipped with a stirrer, a thermometer, a water separator and a condenser, 21.0 kg of citric acid monohydrate (100 mol), 29.7 kg of n-butanol (400 mol), and a catalyst of CH ₂ S0 ₄ 105.0 g (0.5 citric acid mass) %), stir the reaction at 130 ° C ~ 160 ° C for 3.0h ~ 6.0h, synthesize TBC, according to GB 1668-81 acid value, medium control acid value 3 mgKOH / g, the product is obtained by dealcoholization to obtain crude TBC.

2) Acetyl tributyl citrate (ATBC) synthesis

To the crude TBC (35.5 kg) prepared in the step 1), 12.3 kg (120.0 mol) of acetic anhydride was added, and the reaction was carried out at 70 ° C for 1.5 h to synthesize ATBC. After hydrolysis with acetic anhydride, acetic acid was recovered, and 5% sodium carbonate was used. The liquid is neutralized, washed, dehydrated, and the ATBC finished product is obtained.

The obtained ATBC finished product has a purity of 99.3%, an acid value of 0.020 mgKOH/g, a color of 15# (platinum-cobalt), and a moisture content of 0.020%.

Claims

claims

1. A process for synthesizing acylated citrate ester, including the following steps:

1) Preparation of activated carbon-supported catalyst

Soak a certain amount of wooden activated carbon in sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid or sodium bisulfate solution, and immobilize it under stirring conditions at room temperature. The catalyst is filtered and dried to constant weight to obtain an activated carbon immobilized catalyst. ;

2) Synthesis of citrate ester

Add (hydrated) citric acid and alcohol to the reactor, and add a composite catalyst composed of an activated carbon-supported catalyst prepared in step 1) and a non-immobilized catalyst. The non-immobilized catalyst is selected from ¾SO ₄ , benzenesulfonic acid, Toluenesulfonic acid, methanesulfonic acid, _NaHSO or trifluoromethanesulfonic acid is stirred at 130°C to 160°C for 3.0h to 6.0h to perform an esterification reaction, and the alcohol is recovered after filtration to obtain crude citrate ester;

3) Synthesis of acylated citrate esters

Add acid anhydride to the crude citrate ester prepared in step 2), react at 60°C~90°C for 0.5h~3.5h, filter the reaction solution after cooling, recover the acid anhydride or acid from the filtrate, and prepare acylated lemon after post-processing Acid ester finished product.

2. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: in step 1), the wooden activated carbon is activated carbon for decolorization of sugar, the stirring and fixing time is 20h~60h, and the catalyst is baked Dry temperature is 100°C~150°C.

3. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: in step 1), the mass concentration of sulfuric acid, benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid or sodium bisulfate solution is 20 %~50%, the mass ratio to wood activated carbon is 5~20:1.

4. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: the compound catalyst is composed of CH ₂ SO ₄ and benzenesulfonic acid, p-toluenesulfonic acid, methanesulfonic acid or trifluoromethane A component of sulfonic acid.

5. The process for synthesizing acylated citric acid ester according to claim 1, characterized in that: the total amount of compound catalyst in step 2) is 0.2%~2.0% of the mass of (hydrated) citric acid; wherein it is not solid-supported The amount of catalyst used is 0.05%~1.0% of the mass of (hydrated) citric acid.

6. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: the alcohol is an aliphatic linear or branched chain alcohol with a total number of carbon atoms in the molecule of 2 to 13.

7. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: the molar ratio of the (hydrated) citric acid and alcohol is 1:3~7.

8. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: the acid anhydride It is acetic anhydride, propionic anhydride or butyric anhydride.

9. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: the molar ratio of the (hydrated) citric acid and anhydride is 1:1~2.

10. The process for synthesizing acylated citrate ester according to claim 1, characterized in that: in step 3), the post-treatment includes alkali neutralization, water washing and dehydration.