CN1049330A - Process for producing ethyl butyrate - Google Patents

Abstract

Process for producing ethyl butyrate, it is a raw material with butyric acid and ethanol, is catalyzer with sulfuric acid, adopts new proportion scale, the method that adopts ethyl butyrate and water to form binary azeotrope is carried out the continuously dehydrating esterification, again through washing ester, rectification under vacuum, the preparation ethyl butyrate.The present invention is applicable to the production of the ethyl butyrate of various uses such as essence, food, medicine, chemistry, solvent, is particularly useful for the production of edible ethyl butyrate.

Description

Process for producing ethyl butyrate

The present invention relates to the production technique of ethyl butyrate, particularly the production technique of edible ethyl butyrate.

Ethyl butyrate is a colourless transparent liquid, similar pineapple fragrance, and 120.6 ℃ of boiling points, fusing point-93.3 ℃ is soluble in organic solvents such as ethanol and ether, and is water-soluble hardly.It has an extensive use in that essence, food, medicine and chemistry etc. are industrial, for example, can be used for preparing fruit flavouring food flavour and Daqu type wine essence and tobacco flavours etc. such as pineapple, strawberry, banana, grape, can be used for food such as candy, beverage, ice-creams, also can be used for multi-purpose solvent.

U.S. chemical abstract (C.A.), World Patent Index (WPI) and world patent abstract (WPA) before the present invention makes, still find no the production technique similar to the present invention by retrieval.About the more representational document of ethyl butyrate production technique, for example; " (institute of scientific-technical information of Ministry of Chemical Industry edits and publishes world's fine chemistry industry handbook, December nineteen eighty-two the 1st edition, 383 pages), " synthetic flavor handbook (light industry press, September in 1985 the 1st edition, 463 pages) in all introduced the synthetic method of ethyl butyrate, but how the water that generates in the esterification reaction process is removed, and esterification process is carried out continuously, all do not make reports in the above-mentioned document.

Present domestic ethyl butyrate manufacturer adopts traditional single pot of esterification technique intermittently mostly, this technology is summarized as follows: adopting butyric acid and ethanol is raw material, in the preparation process of industrial ethyl butyrate, generally adopting materials such as benzene to form ternary azeotrope with ethanol, water, thus except that the method for anhydrating comparatively common; In the preparation process of edible ethyl butyrate, for pure property and the edible security that keeps product, do not allow material such as benzene to participate in the technological process, so the production of edible ethyl butyrate generally adopts butyric acid and excess ethanol to carry out esterification, after esterification finishes, add in the liquid caustic soda and nonesterified butyric acid, make it to generate Sodium propanecarboxylate and layering, ethyl butyrate thick ester in upper strata is after washing, rectifying, get the ethyl butyrate finished product, lower floor's Sodium propanecarboxylate solution adds the vitriol oil and carries out acidifying, dehydration after reclaiming ethanol, concentrating, thus the recovery part butyric acid.The subject matter that this traditional technology exists is; The butyric acid productive rate only is 73～80%, the raw material consumption height, the production cycle is long, equipment capacity is low, facility investment is big, wastewater discharge is big etc.

The object of the present invention is to provide that a kind of productive rate height, good economy performance, equipment capacity are big, good product quality and the reliable process for producing ethyl butyrate of stable operation.

The objective of the invention is to realize by following method: with butyric acid (content 97～98%) and ethanol (content 92～93%) is raw material, with sulfuric acid is catalyzer, the bed material proportioning is a butyric acid: ethanol=3.0～5.0: 1 (mol ratio), and dripping the material proportioning is butyric acid: ethanol=0.85～1.05: 1 (mol ratio); After treating in the bed material the basic esterification fully of ethanol, will drip and expect to add continuously in the reactor, simultaneously ethyl butyrate and the water form with binary azeotrope be steamed from cat head continuously; The binary azeotrope that steams is after the condensation layering, whole and part lower layer of water of the thick ester of upper strata ethyl butyrate (containing ester amount 95～96%) is shifted out the esterification system, and another part of lower layer of water returns cat head as phegma, works to regulate gentle the replenishing in top and forms the required moisture of binary azeotrope; In whole continuous esterification operating process, control reflux rate and discharging speed, make the ethyl butyrate that shifts out the esterification system and the amount of water, substantially equate with the amount that drips the water that material contains in ethyl butyrate that esterification generates and water and ethanol raw material respectively, keep the composition of reactor internal reaction liquid constant substantially, form thus with water band ester, esterification is carried out continuously and stably; The thick ester of ethyl butyrate through light buck wash, after the rectification under vacuum, the ethyl butyrate finished product.

Ton ethyl butyrate surplus the employing the present invention of State-Owned Wujiang Perfumery has produced 550, nearly 4 years production practice prove that the present invention compared with prior art has the following advantages: (1) productive rate height (the butyric acid productive rate reaches 96.1%, improves about 20% than prior art); (2) raw material consumption is low (compares with the ethyl butyrate raw material consumption standard of national-level enterprise [selecting from " No. the 132nd, light daily use chemicals office of Ministry of Light Industry (87) " literary composition], the butyric acid of special class national enterprises and alcoholic acid unit consumption standard are respectively 0.966 ton/ton and 0.551 ton/ton, the butyric acid of class-one national enterprises and alcoholic acid unit consumption standard are respectively 0.976 ton/ton and 0.568 ton/ton, the butyric acid of second-class state enterprise and alcoholic acid unit consumption standard are respectively 1.015 tons/ton and 0.612 ton/ton, and butyric acid of the present invention and alcoholic acid average quantity used in unit volume blasted only are 0.8102 ton/ton and 0.4860 ton respectively); (3) production cost reduces about 25%; (4) equipment capacity (reactor with unit volume calculates) improves about 8 times; (5) facility investment reduces about 40%; (6) wastewater discharge reduces about 90%; (7) quality product reaches U.S. FCCIII standard.

Accompanying drawing is the process flow diagram of ethyl butyrate continuous esterification.

The major equipment of ethyl butyrate continuous esterification comprises: reaction kettle of the esterification [1], esterification reaction tower [2], condenser [3], water cooler [4], separator [5], under meter [6], [7], [8], [9] and other utility appliance, and as thermometer [T], tensimeter [P] etc.

The present invention is explained in detail by embodiment below in conjunction with accompanying drawing;

1. it is raw material that the present invention for preparing burden adopts butyric acid (content 97～98%) and ethanol (content 92～93%), with sulfuric acid is catalyzer, the bed material proportioning is a butyric acid: ethanol=3.0～5.0: 1 (mol ratio), dripping the material proportioning is butyric acid: ethanol=0.85～1.05: 1 (mol ratio).

2. the total reflux esterification adds the sulfuric acid of bed material and bed material weight 0.7～0.8% in the 500 liter reaction kettle of the esterification [1], in the chuck of reaction kettle of the esterification [1], feed steam, open and stir, about heating total reflux half an hour, when esterification reaction tower [2] tower top temperature is stabilized in 87.8～88.0 ℃, separator [5] inner condensat liquid during layering, the total reflux esterification finishes.

3. after continuously dehydrating esterification total reflux esterification process finishes, promptly begin continuously dehydrating esterification operation.To drip material and add reaction kettle of the esterification [1] bottom continuously by 120～140 liters/hour speed, under the situation of control tower top temperature and quantity of reflux, steam the binary azeotrope of ethyl butyrate and water simultaneously through under meter [9].This binary azeotrope is behind condenser [3], water cooler [4], enter separator [5], after the layering, take out the thick ester in upper strata through under meter [6] by 100～120 liters/hour speed, take out the part of lower layer of water through under meter [7] by about 20 liters/hour speed, another part of lower layer of water passes back into cat head through under meter [8] by 40～50 liters/hour speed.

In whole continuously dehydrating esterification process, vapor pressure 0.58～0.60MPa (gauge pressure) in 87.8～88.0 ℃ of tower top temperatures of control, 118～120 ℃ of tower still reacting liquid temperatures, the chuck, the ester amount that contains of the thick ester of upper strata ethyl butyrate that is taken out is 95～96%, acidity is 0.2～0.4%, and the ester amount that contains of the lower layer of water of being taken out is 0.8～1.0%, acidity is 0.3～0.4%, contain amount of alcohol is 2～4%.

4. wash ester in order to keep the fragrance of edible ethyl butyrate, the thick ester of above-mentioned ethyl butyrate is washed till PH7～8 with light buck (liquid caustic soda consumption be thick ester weight 2～3%) earlier, wash with twice clear water, lower floor's washing water discard.

5. thick ester of ethyl butyrate after rectification under vacuum will be washed and the ethyl butyrate chieftain vacuum of last time suck in the 1000 liter rectifying stills, carry out the steam heating vacuum batch distillation.Go out moisture to the greatest extent earlier, go out the ethyl butyrate chieftain again, when fluid is more and stable, fragrance just often, promptly change out finished product over to.

Whole go out finished product during, vapor pressure 0.15～0.20MPa (gauge pressure) in the serious reciprocal of duty cycle 0.0733～0.0753MPa of control tower, 82～85 ℃ of tower top temperatures, 92～95 ℃ of tower still feed temperatures, the chuck.In early stage that goes out finished product and mid-term, the control reflux rate is 90～100 liters/hour, to go out finished product speed be 150～160 liters/hour; In the later stage that goes out finished product, reflux rate is reduced to 50～30 liters/hour gradually, goes out that finished product speed is also corresponding reduces to 50～30 liters/hour; When going out finished product speed and reduce to about 20 liters/hour, fragrance is commented in sampling at any time, changes slightly as fragrance, promptly finishes finished product.

By the ethyl butyrate that above-mentioned novel process is produced, through the test of national spice product quality examination center, main test result is as follows respectively:

1. vapor-phase chromatography (used gas chromatograph is the GC-7AG type that day island proper Tianjin company produces, and adopts normalization method, detect according to be GB11539-89):

Numbering 1: chromatogram content 99.94%;

Numbering 2: chromatogram content 99.89%;

Numbering 3: chromatogram content 99.94%;

2. conventional method (detect according to be GB4349-84):

Numbering 4: content 99.4%, refractive index (20 ℃) 1.3924;

Numbering 5: content 99.4%, refractive index (20 ℃) 1.3925;

Numbering 6: content 100%, refractive index (20 ℃) 1.3928.

Test result all meets the regulation of GB4349-84 and U.S. FCCIII standard.

Claims (2)

1. process for producing ethyl butyrate, be particularly related to the production technique of edible ethyl butyrate, it comprises that with butyric acid (content 97～98%) and ethanol (content 92～93%) be raw material, with sulfuric acid is catalyzer, ethyl butyrate production technique through processes such as batching, esterification, rectifying, it is characterized in that: determined bed material and dripped the rational proportion of expecting, the proportioning of bed material is a butyric acid: ethanol=3.0～5.0: 1 (mol ratio), and the proportioning that drips material is a butyric acid: ethanol=0.85～1.05: 1 (mol ratio); After treating in the bed material the basic esterification fully of ethanol, will drip and expect to add continuously in the reactor, simultaneously ethyl butyrate and the water form with binary azeotrope be steamed from cat head continuously; The binary azeotrope that steams shifts out the esterification system with the part of the whole and lower layer of water of the thick ester of upper strata ethyl butyrate after the condensation layering, another part of lower layer of water returns cat head as phegma.

2. novel process according to claim 1, it is characterized in that in whole continuous esterification operating process, control reflux rate and discharging speed, make the ethyl butyrate that shifts out the esterification system and the amount of water, substantially equate with the amount that drips the water that material contains in ethyl butyrate that esterification generates and water and ethanol raw material respectively, keep the composition of reactor internal reaction liquid constant substantially.

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