CN1156724A

CN1156724A - Process for producing alkyl ketene dipolymer

Info

Publication number: CN1156724A
Application number: CN 96116630
Authority: CN
Inventors: 徐仁华
Original assignee: TIANMA INDUSTRIAL CHEMICALS PLANT WUXIAN CITY
Current assignee: Suzhou Tianma Fine Chemical Product Co., Ltd.
Priority date: 1996-12-19
Filing date: 1996-12-19
Publication date: 1997-08-13
Anticipated expiration: 2016-12-19
Also published as: CN1052715C

Abstract

A process for preparing alkylketene dimer includes such technological steps as catalytic reaction of molten stearic acid on carbonyl chloride gas to generate acylchloride stearate as intermediate and the hydrogen chloride and CO2 as by-products, addition of acylchloride stearate and solvent in reactor, dripping triethylamine to generate the aqueous solution of triethylamine hydrochloride and the oil solution of alkylketene dimer, and separation of the oil solution of alkylketene dimer. The product, after being emulsified, is used as size tester of paper pulp. The said process has advantages of high quality, no pollution and low cost.

Description

Process for the manufacture of alkyl ketene dimers

The invention relates to a glue testing agent used for papermaking pulp.

In the prior art, different acyl chlorinating agents are selected for synthesizing the alkyl ketene dimer, so that the quality of the prepared alkyl ketene dimer is obviously different. The acyl chlorinating agents used at present are various in variety, such as phosphorus trichloride, thionyl chloride and the like, wherein available chlorine of phosphorus trichloride has a certain utilization rate, and the raw materials are easy to obtain and convenient to operate, so that the acyl chlorinating agent has a wide application range. However, the stearic acid acyl chloride prepared by phosphorus trichloride has low content and contains harmful organophosphorus and inorganic phosphorus impurities, toxic phosphorus is discharged in the production process, the environment is extremely polluted, and the finished product is difficult to separate, so the quality and the yield of the alkyl ketene dimer are directly influenced. The thionyl chloride is used as an acyl chlorinating agent, so that high-purity stearic acid chloride can be prepared, and high-grade alkyl ketene dimer is obtained, but the thionyl chloride and hydrogen chloride generated by the reaction have the defects of serious corrosion to equipment, more three wastes and serious air pollution similar to phosphorus trichloride due to high price. Therefore, the method is rarely adopted in large-scale production and is limited to laboratory application at present.

The invention aims to provide a process for producing alkyl ketene dimer with low cost and good quality.

The technical scheme of the invention is as follows: melting stearic acid, introducing carbonyl chloride gas, and fully reacting under the action of a catalyst to generate an intermediate stearic acid acyl chloride, a byproduct hydrogen chloride and carbon dioxide; (2) adding stearic acid acyl chloride as an intermediate and a solvent into a reaction kettle, dropwise adding triethylamine, generating triethylamine hydrochloride and an alkyl ketene dimer after the reaction is finished, and separating the alkyl ketene dimer. The reaction equation is as follows:

+2(C₂H₅)₃N·HCl

compared with the prior art, the invention has the following advantages:

(1) the stearic acid acyl chloride prepared by carbonyl chloride has high quality (the content is more than 98 percent), does not contain harmful impurities and threewastes (hydrogen chloride and water in the production process obtain a byproduct, namely dilute hydrochloric acid which is indiscriminately used when preparing acid extract liquor), and can obtain high-purity alkyl ketene dimer. Phosphorus trichloride is used as an acyl chlorinating agent, and the content of the obtained stearic acid acyl chloride is only below 95%.

(2) The selection of the catalyst for synthesizing stearic acid acyl chloride is related to the conversion rate, reaction time, product appearance and purity of stearic acid. The conventional catalyst has long reaction time and low speed in the acyl chlorination process, and after the acyl chlorination process is finished, the conventional catalyst cannot be filtered out and is dissolved in the stearic acid acyl chloride, so that the appearance of the catalyst is blackened, and the purity and the product quality of the next process are seriously influenced. The purification needs high vacuum reduced pressure distillation, the equipment cost is high, and the content of the stearic acid acyl chloride is not necessarily increased only by removing color; the stearic acid chloride can be hydrolyzed reversibly gradually under the high temperature or contacting with air for a long time. The catalyst used in the invention is still granular after acyl chlorination, so the appearance of the stearic acid acyl chloride is light yellow or light brown red transparent liquid. The reaction time is short, only 7-10 hours, the reaction time is half of the time before the conventional catalysis, and high-grade stearic acid acyl chloride can be obtained without additional reduced pressure distillation. After the catalyst is subjected to acid chlorination, the color of stearic acid chloride is slightly yellowish (the color of the catalyst), but in the synthesis of the alkyl ketene dimer in the next step, the color can be dissolved in water during extraction with acid water, so that the appearance and purity of the alkyl ketene dimer are not affected.

Example (b): heating 1500 kg of seventeen-carbon or fifteen-carbon stearic acid and 40 kg of catalyst for basic melting, stirring to promote the stearic acid to be completely melted, introducing phosgene gas, and fully reacting under the action of the catalyst to generate an intermediate stearic acid acyl chloride, a byproduct hydrogen chloride and carbon dioxide; the molar ratio of the stearic acid to the carbonyl chloride is 1: 1.3-1.5, when the stearic acid is 1500 kg, about 831-841 kg of the carbonyl chloride and about 418-423 cubic meter are needed, the stearic acid reacts with the carbonyl chloride gas at the reaction temperature of 90-92 ℃, and the reaction is finished within 7-10 hours of ventilation time. Detecting whether a reaction end point is reached by a sampling analysis method; the analysis method comprises the steps of firstly sampling, adding sodium hydroxide for alcoholysis, then adding a standard silver nitrate solution, enabling all chloride ions in the sample to generate a silver chloride solution precipitate, titrating redundant silver nitrate and the standard potassium thiocyanate solution to calculate the total chlorine content in the sample (or analyzing by gas and liquid chromatography), and when the total chlorine content is more than 99 percent and the appearance is pale yellow or light brownish red, reaching the reaction end point, and ending the ventilation at the moment. If the content index is not reached, introducing the phosgene gas continuously until the analysis is qualified. And after the reaction of the stearic acid and the carbonyl chloride gas reaches the end point, continuously introducing nitrogen into the reaction container until the redundant carbonyl chloride gas is driven out, and then finishing introducing the nitrogen. The temperature of the material liquid in the reaction container during the driving of the carbonyl chloride gas is 65-70 ℃, the endof the introduction of nitrogen is based on the determination analysis, the determination method is to extract chloride ions in the mixed solution of the stearic acid chloride and the toluene by water, titrate the chloride ions with the standard silver nitrate and potassium thiocyanate solution to calculate the free chlorine content, and the driving of the carbonyl chloride gas is finished when the free chlorine is less than 0.5 percent. And cooling the temperature of the feed liquid to 40-45 ℃, and carrying out suction filtration on the reaction liquid to obtain a midbody of stearic acid acyl chloride and waste residues (mainly burning or burying the reacted catalyst).

Adding stearic acid chloride serving as an intermediate and a solvent (such as toluene) into a reaction kettle, dropwise adding triethylamine into a feed liquid at 25-30 ℃, heating the feed liquid to 32-35 ℃ within 3-4 hours, keeping the temperature for 2-3 hours, heating the feed liquid to 45-50 ℃, adding an acid extraction liquid such as dilute hydrochloric acid (or dilute sulfuric acid) into the reaction liquid, uniformly stirring, standing at 45-50 ℃, layering after 2-3 hours, separating a lower layer of triethylamine hydrochloride (or triethylamine sulfate) aqueous solution and an upper layer of alkyl ketene dimer oil solution, and separating the alkyl ketene dimer oil solution. The triethylamine hydrochloride aqueous solution is treated by alkali (adding excessive sodium hydroxide or potassium hydroxide liquid) to generate precipitate layering, the upper layer is triethylamine which is dissociated, then solid (sodium hydroxide or potassium hydroxide) is added to carry out alkali dehydration to obtain qualified triethylamine, and the qualified triethylamine is used mechanically in the next reaction, wherein the content of the triethylamine is required to be more than 98%, and the water content is required to be less than 0.03%.

The preparationmethod of the catalyst comprises the following steps: the strong acid styrene cation exchange resin (732 resin for short) needs to be washed by water and then dried before being put into a reaction pot. Putting a strong-acid styrene cation exchange resin as a raw material into a reaction pot, adding 5-6% of dilute hydrochloric acid, reacting for 4-4.5 hours at the temperature of 30-35 ℃ to obtain an acid-treated resin solid, washing the solid with water, drying, and crushing for later use. Adding dimethylformamide into a reaction kettle, slowly pouring the crushed and dried resin and crushed silica gel for later use into the reaction kettle under stirring, heating to 40-45 ℃, reacting for 1-2 hours, pouring out the upper turbid dimethylformamide after precipitation, wherein the lower precipitate is the catalyst required by the invention. The weight ratio of the dimethyl formamide to the resin which is dried and crushed after acid treatment to the silica gel is 150: 50: 3. In addition, before the dimethylformamide is put into the reaction kettle, the reaction kettle is dried in advance.

Claims

1. A process for the manufacture of an alkyl ketene dimer, characterized in that: melting pentadecane or heptadecane stearic acid, introducing carbonyl chloride gas, and reacting under the action of a catalyst to generate an intermediate stearic acid acyl chloride, a byproduct hydrogen chloride and carbon dioxide; (2) adding stearic acid acyl chloride as an intermediate and a solvent into a reaction kettle, dropwise adding triethylamine, generating triethylamine hydrochloride and an alkyl ketene dimer after the reaction is finished, and separating the alkyl ketene dimer.

2. The process for the manufacture of an alkyl ketene dimer according to claim 1, characterized in that: the molar ratio of the stearic acid to the carbonyl chloride is 1: 1.3-1.5, and the stearic acid reacts with the carbonyl chloride gas at the reaction temperature of 90-92 ℃.

3. The process for the manufacture of an alkyl ketene dimer according to claim 1, characterized in that: and after the reaction of the stearic acid and the carbonyl chloride gas reaches the end point, continuously introducing nitrogen into the reaction container until the redundant carbonyl chloride gas is driven out, and then finishing introducing the nitrogen.

4. The process for the manufacture of an alkyl ketene dimer according to claim 3, characterized in that: the temperature of the reaction liquid during the driving of the carbonyl chloride gas is 65-70 ℃, after the nitrogen gas is introduced, the temperature of the reaction liquid is reduced to 40-45 ℃, and the reaction liquid is filtered to obtain the intermediate stearic acid acyl chloride.

5. The process for the manufacture of an alkyl ketene dimer according to claim 1, characterized in that: after adding the stearic acid acyl chloride and the solvent into a reaction kettle, dropwise adding triethylamine at 25-30 ℃, after dropwise adding is completed within 3-4 hours, heating to 32-35 ℃, preserving heat for 2-3 hours, then heating to 45-50 ℃, adding the acidic extract into the reaction liquid, uniformly stirring, standing at 45-50 ℃, layering after 2-3 hours, wherein the lower layer is triethylamine hydrochloride aqueous solution, and the upper layer is alkyl ketene dimer oil solution.

6. The process for the manufacture of an alkyl ketene dimer according to claim 5, characterized in that: the triethylamine hydrochloride aqueous solution is treated by alkali to dissociate triethylamine, and then the triethylamine is obtained by alkali dehydration for the next reaction.

7. The process for the manufacture of an alkyl ketene dimer according to claim 1, characterized in that: the catalyst is prepared by putting a raw material of strong-acid styrene cation exchange resin into a reaction pot, adding dilute hydrochloric acid, reacting for 4-4.5 hours at the temperature of 30-35 ℃ to obtain an acid-treated resin solid, washing the solid with water, drying, and crushing for later use; adding dimethylformamide into a reaction kettle, slowly pouring the crushed and dried resin and crushed silica gel for later use into the reaction kettle under stirring, heating to 40-45 ℃, reacting for 1-2 hours, pouring out the upper turbid dimethylformamide after precipitation, wherein the lower precipitate is the catalyst.

8. The process for the manufacture of an alkyl ketene dimer according to claim 7, characterized in that: the strong acid styrene cation exchange resin needs to be washed by water and then dried by spin before being put into a reaction pot.

9. The process for the manufacture of an alkyl ketene dimer according to claim 7, characterized in that: the weight ratio of the dimethyl formamide to the dried and crushed resin to the silica gel is 150: 50: 3.

10. The process for the manufacture of an alkyl ketene dimer according to claim 7, characterized in that: before the dimethyl formamide is put into the reaction kettle, the reaction kettle is dried in advance.