Background technology
Oxyacetic acid (hydroxyacetic acid; Glycolic acid), claiming oxyacetic acid or glycolic acid again, is that molecular structure is the simplest
α-alcohol acid.Oxyacetic acid is widely used in fields such as matting, daily-use chemical industry, biomedical material and sterilant.The hydroxyl and the carboxyl that contain high reaction activity in the oxyacetic acid molecule simultaneously, thereby have unique metal-chelating ability and effectively in and performance, and corrodibility is little, therefore industrial its aqueous solution of 70% commonly used is as the clean-out system of pipeline, boiler etc., to remove the precipitation of calcium, the formation of magnesium plasma; The oxyacetic acid good water solubility has strong perviousness, can pass stratum corneum by skin absorption, promotes the metabolism of epidermis, eliminates wrinkle of skin, since the nineties in 20th century,
α-alcohol acid becomes the choosing of the certainty of high-grade special cosmetics additive; Self-polymeric reaction can take place in oxyacetic acid, and the polyglycolic acid that obtains (PGA) has excellent biodegradability and biocompatibility, is to study one of the most extensive, that application is maximum Biodegradable material so far.
At present, the company that produces oxyacetic acid in the world mainly contains du pont company, Union Carbide Corporation, Japanese ball and company and German He Kete company etc., and the domestic enterprise that does not still have scale operation.Because oxyacetic acid is of many uses, the market potential demand is big, and the main dependence on import of domestic oxyacetic acid and related products thereof, therefore the national Tenth Five-year plan was once classified oxyacetic acid one of as anxious main basic chemical industry product leaved for development.
The main production method of oxyacetic acid has: (1) cyanide process.With formaldehyde and prussic acid is raw material, and through nucleophilic addition(Adn) synthesis of hydroxy acetonitrile, hydrolysis gets oxyacetic acid again, and also having device to adopt sodium cyanide instead of hydrogen cyanic acid is raw material.This method Technology is simple, stable operation, and output and quality is better, but owing to use the prussiate of severe toxicity, environmental pollution and safe pressure are bigger.(2) formaldehyde carbonylation method.With formaldehyde, carbon monoxide and water is raw material, and reaction obtains oxyacetic acid in the presence of high temperature, high pressure and an acidic catalyst, and yield is about 90%, and wherein an acidic catalyst is sulfuric acid, hydrochloric acid or phosphoric acid.This raw materials technology cost is low, but technical difficulty is big, and one-time investment is big, and equipment need bear the pressure of 30.4-91.2MPa, and this is present external topmost industrial method.(3) Mono Chloro Acetic Acid hydrolysis method.Mono Chloro Acetic Acid and sodium hydroxide react in the presence of methyl alcohol and obtain hydroxy methyl acetate, and hydrolysis obtains oxyacetic acid then.This is domestic traditional production technique, because inefficiency only is suitable for small-scale production, there is heavy corrosion in the existence of chlorion simultaneously to production unit.
Although oxyacetic acid has multiple synthesis technique, no matter the difficult problem that improves of the product purity which kind of technology all exists negative ion impurity difficulty to remove causes.Commercially pure oxyacetic acid product generally is its aqueous solution of 70%, and temperature just can cause oxyacetic acid decomposition dehydration autohemagglutination more than 80 ℃, and the methods such as concentrate drying by routine are difficult to obtain high purity hydroxyl acetate crystal like this.Therefore purity and crystal refining technology have constituted the core link of weighing oxyacetic acid production level height.
Liao Chuanping once reported under the sodium hydroxide katalysis, and through the novel method of Cannizzaro reaction synthesis of hydroxy acetate [synthetic chemistry, 2008,16(4): 470-471], but this technology both needed to react at low temperatures from oxalic dialdehyde, and high temperature concentrates again; Need simultaneously to handle metallic cation with strong-acid ion exchange resin, technological process is loaded down with trivial details, and the production cost height is through repeatedly repeated experiments detection discovery by product is many, product purity is low.
Summary of the invention
Technical problem to be solved by this invention is to propose a kind of oxalic dialdehyde intramolecularly discrimination method at above-mentioned the deficiencies in the prior art to prepare oxyacetic acid, and this technological process is simple, and production cost is low, and by product is few, the product purity height.
The present invention for the technical scheme that problem adopted of the above-mentioned proposition of solution is: oxalic dialdehyde intramolecularly discrimination method prepares oxyacetic acid, it is characterized in that including following steps:
1) adopting calcium hydroxide is disproportionation catalyst, is configured to aqua calcis, drips mass concentration then and is 40% glyoxal water solution and carry out disproportionation reaction, is added dropwise to complete follow-up continuation of insurance temperature and reacts 0.5-1 hour, obtains suspended state Calcium Glycolate precipitation mixture;
2) directly in step 1) gained precipitation mixture, add with the vitriol oil acid out of mole numbers such as calcium hydroxide or with precipitation mixture and filter earlier, it is 50% sulfuric acid acid out that the gained throw out is used the mass concentration with mole numbers such as calcium hydroxides, all form oxyacetic acid and calcium sulfate precipitation, filter, filtrate is elementary oxyacetic acid solution, filtrate refilters after being concentrated into no moisture, to remove a small amount of calcium sulfate of dissolved in filtrate;
3) step 2) the filtrate thin up that obtains behind the filtering calcium sulfate to the mass concentration of oxyacetic acid is 5-15%, adds barium acetate or hydrated barta and thoroughly removes SO
4 2-Ion adds wood activated charcoal simultaneously and decolours and help filter, filters and removes barium sulfate precipitate and gac, and filtrate concentrates, and can obtain oxyacetic acid solution.
Press such scheme, the mass percent concentration of the described aqua calcis of step 1) is 5-40%, and wherein oxalic dialdehyde is 1:0.5-1.2 with the mol ratio of calcium hydroxide.
Press such scheme, the described disproportionation reaction temperature of step 1) is 0~25 ℃.
Press such scheme, step 3) also comprises the crystallization of oxyacetic acid solution deep is obtained high purity hydroxyl acetate crystal, described degree of depth crystallization is to be 80-95% with oxyacetic acid solution rotating evaporation concentration to mass percent concentration, 50-65 ℃ of rotary evaporation temperature, vacuum tightness 0.080-0.095MPa, cooling can obtain the oxyacetic acid crystal, is that 60% oxyacetic acid solution is as the detergent washing crystallization with mass percent concentration again, through vacuum-drying, obtain purified oxyacetic acid crystal.
Press such scheme, step 3) also comprises the crystallization of oxyacetic acid solution deep is obtained high purity hydroxyl acetate crystal, described degree of depth crystallization is to anhydrous fractionating out with oxyacetic acid solution rotating evaporation concentration, enriched material extracts with acetone solvent, behind the extraction liquid precipitation or directly crystallisation by cooling obtains purified oxyacetic acid crystal.
Detect through HPLC, the oxalic dialdehyde transformation efficiency after the degree of depth crystallization is more than 98%, and oxyacetic acid purity is greater than 99.5%, and the oxyacetic acid yield is seen accompanying drawing 1 greater than 90%().
In theory, alkali metal hydroxide such as sodium hydroxide or potassium hydroxide can be as the disproportionation catalyst of the aldehyde of no α-H, but the alkalescence of this class alkali is too strong, be easy to cause side reaction, oxyacetic acid is to utilize simultaneous hydroxyl of intramolecularly and carboxyl and calcium, barium plasma to form water miscible complex compound or salt as the cardinal principle of clean-out system.In the alkaline environment of certain intensity, oxyacetic acid can form the hydroxyl acetate precipitation with calcium, barium plasma, and acidifying after the precipitate and separate can be obtained oxyacetic acid.Wherein barium belongs to heavy metal ion, should avoid a large amount of uses, and therefore selecting with calcium hydroxide is Primary Catalysts, and the mass percent concentration of alkali can be advisable with about 20% at 5-40%; The disproportionation reaction temperature is controlled between 0~25 ℃, takes all factors into consideration from cost and reaction efficiency, and temperature of reaction is advisable with 20~25 ℃.Wherein temperature surpasses 25 ℃ and easily causes side reactions such as oxidation or polymerization, reactant color burn, component complexity.It is standard that disproportionation reaction time temperature of reaction when dripping is no more than 25 ℃, about 1 hour of the time that generally drips, is added dropwise to complete follow-up continuation of insurance temperature and reacts 0.5-1 hour.
From by-product salt can be easily by precipitate and separate, can fully utilize two factors and consider that the laboratory has been carried out in the alkali with sulfuric acid, phosphoric acid respectively and tested.The vitriol of calcium and barium, phosphoric acid salt all can form precipitation, but from the cost factor consideration, the last sulfuric acid of selecting of experiment is as neutralizing acid, and product is also available hydrochloric acid neutralization when requirement is hanged down to chlorion.
Antacid concentration and consumption:,, or will neutralize with 50% sulfuric acid again after the Calcium Glycolate filtering separation with vitriol oil neutralization for reducing the amount of concentrating.In and the time answer control reaction temperature to be no more than 25 ℃.The vitriolic consumption is identical with disproportionation alkali consumption mole number.
The removal of sulfate anion: the solubleness of calcium sulfate in water is about 0.2g under the normal temperature, therefore with still having a spot of SO in the oxyacetic acid solution after the sulfuric acid parsing (forming oxyacetic acid and calcium sulfate precipitation)
4 2-Ion, its content is far longer than SO in the finished product
4 2-Ionic concn needs essence to remove less than the requirement of 30ppm.General energy and the SO of using
4 2-Ion forms the alkali or the salt of the lower sulfate precipitation of solubility product.Here need to seek a kind ofly can make SO
4 2-Ion does not exceed standard, and avoids the introducing of excess salt again and causes oxyacetic acid to reduce product yield because of complexing.Experimental result shows, uses barium acetate or hydrated barta to achieve the goal, and removes SO
4 2-Solution for vacuum concentration behind the ion can obtain the oxyacetic acid solution of mass percent 70%.
Reaction principle of the present invention is: the aldehyde of no α-H issues living intramolecular redox in the effect of the alkali of certain intensity, and a part aldehyde is oxidized to acid as a result, and another molecule aldehyde is reduced into alcohol, promptly intramolecular disproportionation reaction.At first the carbonyl of hydroxyl radical negative ion and aldehyde carries out nucleophilic addition(Adn), forms the hydroxyl oxygen negative ion; Under catalyst action, the Sauerstoffatom that has negative charge in the hydroxyl oxygen negative ion has been strengthened the ortho position carbon atom and has been repelled electronic capability, makes hydrogen band on the carbon a pair of electronics and transfers on the carbonylic carbon atom of another molecule aldehyde radical with the negative hydrogen ion form.Wherein, the aldehyde that provides negative hydrogen ion is donor (being oxidized to acid); Accepting negative hydrogen ion ionic aldehyde is acceptor (being reduced into alcohol).For oxalic dialdehyde and say, be intramolecular selfoxidation-reduction reaction, an aldehyde radical is oxidized, and another aldehyde radical is reduced, and oxalic dialdehyde obtains hydroxyl acetate through the intramolecularly catalytic disproportionation, obtains oxyacetic acid after the acidifying.From the disproportionation reaction principle analysis, in the presence of catalyzer, use the alkali of certain intensity can finish disproportionation reaction.Oxyacetic acid not only can with the basic metal salify of introducing, but also can form complex compound and consume oxyacetic acid with metal ion.In the acidification step after finishing disproportionation reaction,, just can solve acidifying simultaneously and remove the negatively charged ion problem of introducing, therefore can select targetedly disproportionation alkali and neutralizing acid if the acid of use can form the long-pending less salt of content with the alkali of disproportionation.
Beneficial effect of the present invention is:
1) with calcium hydroxide oxalic dialdehyde is carried out the intramolecularly disproportionation reaction and prepare oxyacetic acid reaction yield height, low in the pollution of the environment, can overcome the deficiency of traditional cyanide process or Mono Chloro Acetic Acid hydrolysis production technique, meet the requirement of Green Chemistry development;
2) carry out disproportionation reaction at normal temperatures and pressures, equipment is not had particular requirement, simple to operate, by product can fully utilize, and can realize cleaner production;
3) reaction preference height, product impurity is few, and the purity height has overcome the difficulty that the high-purity crystal that causes because of impurity is difficult to form, for convenience has been created in the preparation of high purity hydroxyl acetate crystalline.
Embodiment
The present invention is described in further detail below in conjunction with example.
Embodiment 1:
In three mouthfuls of reaction flasks of 1000ml, add 40g calcium hydroxide and 500ml water (mass percent concentration of aqua calcis is 7.4%), water-bath, mechanical stirring, dropping 145g mass concentration is 40% glyoxal solution from dropping funnel, rate of addition is no more than 25 ℃ with control reaction temperature and is advisable, be added dropwise to complete the back 20-25 ℃ of insulation reaction 1 hour, obtain suspended state Calcium Glycolate precipitation mixture.In suspended state Calcium Glycolate precipitation mixture, add the 55g vitriol oil (0.54mol) by dropping funnel while stirring and carry out acidifying, the filtering calcium sulfate precipitation, the filtrate vacuum concentration is to anhydrous timesharing, the a small amount of calcium sulfate that is dissolved in the filtrate is separated out, filtering separation, it is 12% that filtrate is diluted to the oxyacetic acid mass concentration with deionized water, removes micro-SO with the barium acetate solution of mass percent concentration 10%
4 2-Ion is up to no new white BaSO
4Till precipitation occurs, add the wood activated charcoal that 1g has decolouring and filtrating aid function, 50-60 ℃ of heating 5 minutes filtered, and filtrate decompression concentrates, and can obtain concentration and be 70% oxyacetic acid solution.HPLC detects, oxyacetic acid purity 〉=98% in the sample, oxyacetic acid yield 〉=92%.
Embodiment 2:
In three mouthfuls of reaction flasks of 1000ml, add 40g calcium hydroxide and 300ml water (mass percent concentration is 11.8%), water-bath, mechanical stirring, dropping 145g mass concentration is 40% glyoxal solution from dropping funnel, rate of addition is no more than 25 ℃ with control reaction temperature and is advisable, be added dropwise to complete the back 20-25 ℃ of insulation reaction 1 hour, obtain suspended state Calcium Glycolate precipitation mixture.Reaction mixture filters, and the filter cake deionized water wash obtains the precipitation of Calcium Glycolate.Throw out is that 50% sulphuric acid soln carries out acidifying with the 108g mass concentration, the filtering calcium sulfate precipitation, and filtrate removes micro-SO with the barium acetate solution of mass concentration 10%
4 2-Ion is up to no new BaSO
4Till precipitation occurs.Add the decolouring of 1g powdery wood activated charcoal and also filter, filtrate decompression concentrates, and can obtain mass concentration and be 70% oxyacetic acid solution.Oxyacetic acid HPLC detects, oxyacetic acid purity 〉=98% in the sample, oxyacetic acid yield 〉=90%.
Embodiment 3:
The oxyacetic acid solution continuation rotary evaporation that embodiment 1 is obtained is concentrated into the oxyacetic acid mass concentration more than 85%, 50-65 ℃ of rotary evaporation temperature, and vacuum tightness 0.080-0.095MPa is cooled to room temperature, promptly has thick oxyacetic acid crystal to separate out.Filter, with mass concentration be 60% oxyacetic acid solution as detergent washing crystal secondary, the reduced vacuum drying obtains purified oxyacetic acid crystal.HPLC detects, oxyacetic acid content purity 〉=99%, crystal oxyacetic acid yield 〉=75%.
Embodiment 4:
The oxyacetic acid solution continuation rotary evaporation that embodiment 2 is obtained is concentrated into anhydrous fractionating out.The enriched material acetone extract is cooled to room temperature, and filtration drying promptly obtains purified oxyacetic acid crystal; Or after the acetone extract thing thoroughly removed solvent, use deionized water dissolving, and make the oxyacetic acid mass concentration more than 85%, crystallisation by cooling filters drying under reduced pressure, also can obtain purified oxyacetic acid crystal.HPLC detects, oxyacetic acid content purity 〉=99.5%, crystal oxyacetic acid yield 〉=70%.