CN1377872A

CN1377872A - Binary C4-C6 carboxylic acids and the separation, purifying and use of their mixtures

Info

Publication number: CN1377872A
Application number: CN 01105870
Authority: CN
Inventors: 吴兆宏
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-04-05
Filing date: 2001-04-05
Publication date: 2002-11-06

Abstract

The C4-C6 binary carboxylic acid mixture material is first heated to about 200 deg.c and succinic acid and glutaric acid are converted into corresponding acid anhydrides under the action of heat and catalyst. Water is separated with entrainer and the entrainer is then recovered through distillation. Succinic anhydride and glutaric anhydride are distilled out successively and the residual liquid is hydrolyzed and crystallized to obtain adipic acid. So, the three kinds of binary acid are separated and may be further purified and produced into pure binary acids and anhydrides or be used in producing other chemicals. Without the demerits of coking, pipe chocking, etc., the said process has practical industrial application valve.

Description

Separation, purification and the utilization of carbon 4～6 di-carboxylic acid and composition thereof

The present invention relates to the separating and purifying method of a kind of di-carboxylic acid of containing 4～6 carbon atoms that has improved and composition thereof.Can make the di-carboxylic acid or the dicarboxylic acid anhydride of pure state.Perhaps no longer purify and directly be used for producing valuable fine chemicals.

The di-carboxylic acid mixture that contains 4～6 carbon atoms is the by product of production processes such as some chemical industry, medicine often.

Carbon

4,5,6 dicarboxylic acid on the domestic market are typical case representatives, its by product when producing hexanodioic acid, and main component is Succinic Acid, pentanedioic acid and hexanodioic acid, and other impurity.Also has paraffin oxidation by product etc.

The separation of carbon 4～6 mixed dicarboxylic acids has many methods.For example first esterification is separated mixing acid or utilizes through processes such as rectifying, hydrolysis and dehydrations again.Also has the combination of extraction process, urea complexation, ammoniation process, distillation method and aforesaid method.Wherein distillation method is fairly simple.Generally all utilize Succinic Acid and pentanedioic acid to dewater based on the patent of distillation method abroad and generate the character of corresponding acid anhydrides, in the rectification under vacuum tower, dewater simultaneously and steam succinic anhydride and glutaric anhydride, resistates is with 4～7% nitric acid hydrolysis in the still, recrystallize separate hexanodioic acid.(USP 3359283, and USP4014903) still there are many shortcomings in this method.At first be the operational temperature conditions harshness, require to reach 225～260 ℃.And under such condition,

carbon

4,5,6 dicarboxylic acid carbonization phenomenon of coking in still kettle is very serious, shows that material decomposes easily under high like this temperature condition, and productive rate also decreases, and rectifying device is difficult to clean.Secondly long reaction time fully dewaters in order to make Succinic Acid, needs the sufficiently long reaction times.The 3rd owing to begin the dehydration deficiency, in stage of rectification, can steam water vapor when particularly steaming Succinic anhydried, and when it entered water condenser, a small amount of succinic anhydride of wherein carrying under one's arms very easily directly became solid in pipeline, result in blockage, and makes troubles to operation.Also have, the purity of product is lower, can only reach 115～118 ℃ as the fusing point of Succinic anhydried.

At the problems referred to above, the present invention has made corresponding improvement: one, used catalyzer in order to accelerate dehydration reaction, for example sulfuric acid can reduce temperature of reaction and shorten the reaction times, and consumption is 0.2～1.5% of a raw material.Two, process is divided into dehydration and two steps of rectifying, has adopted band aqua, for example dimethylbenzene in the water smoking.Three, accomplish water smoking water outlet as much as possible in operation, can reduce the aquifer yield of stage of rectification like this, particularly not water outlet simultaneously when steaming succinic anhydride just can alleviate the plugging phenomenon greatly.Adopting the band aqua is very favorable to this point, and can also improve the quality of Succinic anhydried, can sell without just handling again.The speed of response of pentanedioic acid dehydration is slower, but dewater simultaneously and plugging phenomenon that rectifying causes light.

Further set forth design of the present invention below in conjunction with accompanying drawing and example.

Description of drawings:

Fig. 1: 1. dehydration reactor 2. packing towers 3. condensers 4. water-and-oil separators 5. water legs

Fig. 2: 1. rectifying still 2. rectifying tower 3. condensers 4. reflux splitters 5. succinic anhydride grooves 6. middle runnings grooves

7. glutaric anhydride groove 8. condensers 9. solvent recuperation grooves 10. cold-traps 11. water legs

1, dehydration: raw material such as

carbon

4,5,6 dicarboxylic acid are added in the dehydration reactor (1), add solvent again, heat fused adds catalyzer then, and further heating up reaches 200～220 ℃.Solvent is gone into condenser (3) with the reaction water band behind packing tower (2), lime set passes back into tower through water-and-oil separator (4) oil phase, and water flows into water leg (5).When obviously slowing down, the rate of output water stops dehydration reaction.

2, rectifying: device changes Fig. 2 into.The temperature of condenser (3) is higher than 120 ℃, begins to use the rough vacuum system, and rectifying still (1) heating at first steams solvent, goes into accumulator tank (9) in condenser (8) after the condensation.Steam succinic anhydride then, the liquid that condenser (3) gets off passes back into tower through reflux splitter (a 4) part, and a part is gone into succinic anhydride groove (5).Steam and collect middle runnings subsequently.Steam glutaric anhydride at last, switch to high vacuum system this moment, steams a thing part and pass back into tower, and a part is gone into the glutaric anhydride groove.Steam is gone into water leg (11) after cold-trap (10) condensation.When reaching 160 ℃, tower top temperature stops rectifying.Raffinate is put into crystallizer after with dilute nitric acid dissolution, gets hexanodioic acid through crystallisation by cooling, centrifuging.

How a large amount of natural resourcess of Chemical Manufacture consumption more make full use of limited resources, and can be related to chemical industry Sustainable development.This also is the main mission of Green Chemistry.Method of the present invention makes the separation of dicarboxylic acid of containing 4～6 carbon atoms and composition thereof and purifies and can realize smoothly with higher yield industrial, thereby makes this a part of resource can obtain optimized utilization, social benefit and economic benefit highly significant.

Embodiment one

In dehydration reactor, add 400 parts of (quality)

carbon

4,5,6 dicarboxylic acid, heat fused.Add 4.5 parts in sulfuric acid again.The consumption of dimethylbenzene is decided by temperature of reaction.Be reflected at 200～220 ℃ and carried out 3 hours, the water of deviating from divides in water-and-oil separator and goes, and dimethylbenzene all refluxes.Dehydration changes device into rectifying after finishing.Earlier slowly heat and vacuumize and steam dimethylbenzene, condenser (3) and fraction collection groove all keep 120 ℃.When working pressure is 2.7～6.7kPa, 185～210 ℃ of still temperature, 40～50 ℃ of top temperature.Dimethylbenzene is recovered into the dimethylbenzene groove with cooling water condensation in condenser (8).Steam Succinic anhydried then, when the operation absolute pressure is 2.7kPa, 200～215 ℃ of still temperature.The beginning reflux ratio is 1, brings up to 2 gradually, collects about 140 ℃ fraction and goes into the Succinic anhydried groove.The top temperature begins to rise, and valve is switched to the middle distillate groove.At last system is switched to high vacuum and steam Pyroglutaric acid, the operation absolute pressure is reduced to 660Pa, and reflux ratio reduces to 0.3, surpasses 160 ℃ up to the top temperature and stops distillation.The Pyroglutaric acid fraction enters the glutaric anhydride groove, and the steam that steams is simultaneously gone into water leg after cold-trap (10) condensation.Rectifying finishes the back with 4～7% nitric acid dissolve raffinates, gets adipic acid crystals again after crystallisation by cooling and the centrifugation.117～120 ℃ of the fusing points of the cymogene dicarboxylic anhydride of gained behind the recrystallization are 119～121 ℃.41～49 ℃ of the thick Pyroglutaric acid fusing points of gained can reach 54.5～56.5 ℃ through aftertreatment.Also get pentanedioic acid after hydrolyzable, crystallization, centrifuging, washing, the drying.Hexanodioic acid is 150～153 ℃ through the aftertreatment fusing point.

Embodiment two

In esterifier, add above-mentioned 47 parts of thick Pyroglutaric acids (quality), 146 parts of 2-Ethylhexyl Alcohols, heated and stirred also adds 0.2 part of catalyst Ti acid esters.Esterification was carried out 2.5 hours at 177～234 ℃ under nitrogen protection, and reaction water is refluxed by 2-Ethylhexyl Alcohol and takes out of.Remainder catalyst is removed with alkali in thick ester cooling back, and gets the pentanedioic acid di-isooctyl after dealcoholysis, decolouring, 0.14 milligram of potassium hydroxide/gram of acid number, and color and luster is No. 35 (platinum-cobalt method).

Claims

1. one kind is separated the method for purifying and utilizing the di-carboxylic acid mixture that contains 4～6 carbon atoms.It is characterized in that di-carboxylic acid is heated to 200～220 ℃, use catalyzer to make Succinic Acid and pentanedioic acid be dehydrated into corresponding acid anhydrides.Adopt solvent (band aqua) band water and improve the aquifer yield in water smoking as far as possible.Reclaim solvent, steam Succinic anhydried and Pyroglutaric acid with rectification under vacuum again, and the water that generates.Raffinate gets hexanodioic acid through hydrolysis, crystallization.

2. as claims 1 described method, except can be used for separating mixed dibasic acid, also be applicable to the production of producing Succinic anhydried by Succinic Acid.

3. as claims 1 described method, also be applicable to the production of producing Pyroglutaric acid by pentanedioic acid.

4. as claims 1 described method, used catalyzer is general acidic substance, and sulfuric acid only is an example.

5. as claims 1 described method, used band aqua is general organic solvent, and dimethylbenzene only is an example.

6. as claims 1,4,5 described methods, the reaction conditions in water smoking is a normal pressure, 200～215 ℃.

7. as claims 1,4,5 described methods, the rectifying fs mainly is to reclaim solvent and steam Succinic anhydried, and operational condition is absolute pressure 2.7～6.7kPa, 200～215 ℃ of still temperature.

8. as claims 1,4,5 described methods, the rectifying subordinate phase mainly is the water that steams Pyroglutaric acid and generation, and operational condition is absolute pressure 660Pa～1.3kPa, 190～215 ℃ of still temperature.

9. as claims 1,4,5 described methods, resulting Pyroglutaric acid can directly use through purifying as being used to produce fine chemicals such as glutarate class again.

10. as claims 1,2,3 described methods, resulting Succinic anhydried, Pyroglutaric acid and hexanodioic acid can adopt general known physical method and chemical process further to purify, and make Succinic anhydried, Pyroglutaric acid and the hexanodioic acid of pure state.