The preparation method of ethyl malonate
Technical field
The present invention relates to a kind of preparation method of organic acid acetic, specifically is a kind of preparation method of ethyl malonate.
Background technology
The production of ethyl malonate all is to adopt a kind of traditional production process before this at home, promptly utilizes the cyanoacetic acid and the ethanol synthetic under 98% sulphuric acid catalysis effect that generate in the technological process.The raw material of main processes and use comprises:
1, neutralization reaction process: raw material is Mono Chloro Acetic Acid (the molecular formula ClCH of 320Kg97%
2COOH), the yellow soda ash (Na of 180Kg99%
2CO
3).The yellow soda ash of 180Kg99% is become the saturated solution about 34% with the hot water dissolving, be used for then load weighted 320Kg97% in the dropwise reaction still Mono Chloro Acetic Acid, stir to make the acid-base neutralisation reaction take place, control terminal point pH value equals 7.0.Obtain the reaction product sodium chloroacetate solution.Reaction equation:
2ClCH
2COOH+Na
2CO
3→2ClCH
2COONa+H
2O+CO
2
2, cyanogenation process: the product sodium chloroacetate solution that uses the front to obtain is raw material, and natural reaction generates cyanoacetic acid sodium (CNCH with stirring down after sodium cyanide (NaCN) aqueous solution of the 550KG30% that measures
2COONa) solution.Reaction equation:
ClCH
2COONa+NaCN→CNCH
2COONa+NaCl
3, acidification reaction process: the cyanoacetic acid sodium solution with the front obtains, after the hydrochloric acid soln of the 420Kg31% that measures mixes, under agitation carry out natural reaction, obtain cyanoacetic acid solution.Reaction equation:
CNCH
2COONa+HCl→CNCH
2COOH+NaCl
4, vacuum hydro-extraction and esterification reaction process: the cyanoacetic acid solution that in reaction kettle, will obtain is under vacuum state; Utilize the heating of still jacket steam; Do not stop to stir the moisture that makes in the solution and be evaporated gradually and separate, the moisture content in the control material is in 5%.The spirituous solution and the vitriol oil of 580Kg98% that under whipped state, add the 400KG95% measure after the venting vacuum successively, and control the temperature of reaction that adds sulfuric acid process through control adding vitriolic speed and be not more than 75 ℃.Add and be incubated esterification time about 5 hours behind the sulfuric acid, the highest control of temperature is reduced to normal temperature then less than 100 ℃, has promptly obtained ethyl malonate (molecular formula CH
2(COOC
2H
5)
2) crude mixture.The main reaction equation:
CNCH
2COOH+2CH
3CH
2OH+H
2SO
4→CH
2(COOC
2H
5)
2+NH
4HSO
4
5, water washing process: promptly with the water of 1400Kg with after esterification reaction product mixes, standing demix is removed refuses such as remaining a large amount of salt of the water miscible esterification process of lower floor and acid, obtains the bullion of upper strata ethyl malonate.
6, rectification and purification: utilize distillation operation to make the ethyl malonate bullion be converted into final highly purified ethyl malonate product.
The shortcoming that traditional production process is the most outstanding is exactly in esterification process, to have used sulfuric acid to make catalyzer and produced a large amount of acid waste water, has caused environmental pollution or has brought bigger environmental protection pressure, has increased processing cost.And in esterification process, produced a large amount of waste gas hydrogenchloride, corroded equipment.Vigorously advocate under the policy guide of cleaner production in country at present, vast production commercial city produces ethyl malonate in the technology of actively seeking a kind of comparison environmental protection.
Summary of the invention
The preparation method who the purpose of this invention is to provide a kind of ethyl malonate; Adopt the 12-tungstophosphoric acid as esterifying catalyst, reaction process is safer, need not add a large amount of water after reaction finishes and wash material; Reduced the consumption of ethanol and ethyl malonate; Conversion rate of esterification has increased, and the growing amount of ethyl malonate has improved, simultaneously because solid acid also greatly reduces the cost of catalyzer through recycling.
Technical scheme of the present invention is following:
The preparation method of ethyl malonate; Include steps such as neutralization, cyaniding, acidifying, vacuum hydro-extraction and esterification, washing, rectification and purification; Described neutralization is to use Mono Chloro Acetic Acid and saturated aqueous sodium carbonate reaction to generate sodium chloroacetate; Described cyaniding is to utilize neutralization to accomplish liquid to carry out cyanogenation with sodium cyanide and generate the cyanoacetic acid sodium solution, and described acidifying is to utilize cyanoacetic acid sodium and hydrochloric acid reaction generation cyanoacetic acid, described vacuum hydro-extraction and esterification be with the cyanoacetic acid solution that obtains under vacuum state; Heating makes that moisture evaporation is separated in the solution; Control cyanoacetic acid moisture content is below 5%, utilizes the cyanoacetic acid and the ethanol that generate under the katalysis of catalyzer, to generate ethyl malonate, and the catalyzer that it is characterized in that the employing in the described esterif iotacation step is the 12-tungstophosphoric acid; The weight of 12-tungstophosphoric acid is the 4-6% of chloroacetic weight, and temperature of reaction is controlled between 60-110 ℃.
The preparation method of described ethyl malonate is characterized in that: in the described neutralization procedure, the pH value of control reaction end is between 7.0-7.2; In the cyaniding step, control reaction top temperature is between 100-110 ℃; In the acidification step, control reaction temperature is below 50 ℃; In the esterif iotacation step, control reaction temperature is between 80-110 ℃.
Catalyzer 12-tungstophosphoric acid, molecular structural formula H
3PO
412WO
3XH
2O, molecular formula
H
3[P (W
3O
10)
4] XH
2O, molecular weight 2880.05 (anhydrous).
Compared with prior art, the present invention has following characteristics:
When (1) esterification is operated; Traditional technology causes temperature of reaction to be prone to sharply raise owing to adding a large amount of vitriol oils, causes material to be taken out of reaction kettle by gas easily, danger such as personnel's injury and equipment explosion occur; And novel process reacting balance, thereby existence that just should danger;
(2) reduction of production cost; Be owing to adopted solid acid catalysis in the novel process; Need not add a large amount of water behind the reaction result and wash material, reduce the consumption of ethanol and ethyl malonate, simultaneously because solid acid also greatly reduces the cost of catalyzer through recycling; Be that conversion rate of esterification has increased, the growing amount of ethyl malonate has improved.
Traditional technology and solid acid catalysis method novel process effect comparison chart:
Project name |
Traditional technology |
Novel process |
Catalyst levels/batch |
580KG98% sulfuric acid |
Solid acid 15KG |
Amount of ethanol/batch |
400KG |
360KG |
The acid waste water amount that produces/batch |
3000KG |
0KG |
The hydrogen chloride gas scale of construction that discharges/batch |
About 18KG |
0KG |
The esterification process operating effect |
The too fast material that dashes of reaction appears easily |
Molecular balance is easy to operate |
Ethyl malonate growing amount after esterification is accomplished |
460KG |
480KG |
Production cost |
Cost is high |
Cost reduces |
Embodiment
(1) equipment is prepared: the enamel stirred autoclave of a 2000L (attached access water coolant, water vapor, blowdown condenser); 1 of the poidometer measuring tank of 800L (as depositing liquid sodium cyanide), 3 of the poidometer measuring tanks of 500L (being used for depositing saturated sodium carbonate solution, hydrochloric acid soln and ethanol respectively); One of 500L vacuumfilter, one in vacuum pump; One of the thick ester receiving tank of 800L; Other off-set facility is some.
(2) technical process: neutralization-cyaniding-thick ester-rectifying of acidifying-dehydration-esterification-filtration-De gets finished product.
(3) operation steps:
1, neutralization reaction process: raw material is Mono Chloro Acetic Acid (the molecular formula ClCH of 320Kg97%
2COOH), the yellow soda ash (Na of 180Kg99%
2CO
3).The yellow soda ash of 180Kg99% is become the saturated solution about 34% with the hot water dissolving, be used for then load weighted 320Kg97% in the dropwise reaction still Mono Chloro Acetic Acid, stir to make the acid-base neutralisation reaction take place, control terminal point pH value equals 7.0.Obtain the reaction product sodium chloroacetate solution; Reaction equation:
2ClCH
2COOH+Na
2CO
3→2ClCH
2COONa+H
2O+CO
2
2, cyanogenation process: the product sodium chloroacetate solution that uses the front to obtain is raw material, and natural reaction generates cyanoacetic acid sodium (CNCH with stirring down after sodium cyanide (NaCN) aqueous solution of the 550KG30% that measures
2COONa) solution; Reaction equation:
ClCH
2COONa+NaCN→CNCH
2COONa+NaCl
3, acidification reaction process: the cyanoacetic acid sodium solution with the front obtains, after the hydrochloric acid soln of the 420Kg31% that measures mixes, under agitation carry out natural reaction, obtain cyanoacetic acid solution; Reaction equation:
CNCH
2COONa+HCl→CNCH
2COOH+NaCl
4, vacuum hydro-extraction and solid acid catalysis esterification: the cyanoacetic acid solution that in reaction kettle, will obtain is under vacuum state; Utilize the heating of still jacket steam; Do not stop to stir the moisture that makes in the solution and be evaporated gradually and separate, the moisture content in the control cyanoacetic acid material is in 5%; The ethanol that adds 360KG95% then adds the solid catalyst 12-tungstophosphoric acid of 15KG simultaneously, and feeds HCL gas, stirs the insulation back flow reaction, and temperature is controlled in 110 ℃ from low to high, and the reaction times is 6 hours; Reaction equation:
CNCH
2COOH+2CH
3CH
2OH→CH
2(COOC
2H
5)
2+NH
3
5, suction filtration process: be cooled to 50 ℃, feed liquid put into the suction filtration jar continuously carry out the suction filtration jar and carry out suction filtration, obtain thick ester;
6, regulate thick ester PH to neutral, change rectifying over to and obtain the ethyl malonate finished product.
In the described neutralization procedure, the pH value of control reaction end is between 7.0-7.2; In the cyaniding step, control reaction top temperature is between 100-110 ℃; In the acidification step, control reaction temperature is below 50 ℃; In the esterif iotacation step, control reaction temperature is between 80-110 ℃.