CN1244538C

CN1244538C - Production of isobutyl isobutyrate from isobutyraldehyde by condensation

Info

Publication number: CN1244538C
Application number: CN 03111256
Authority: CN
Inventors: 王晶; 于伟民
Original assignee: HEILONGJIANG PROVINCIAL PETROLEUM CHEMISTRY INST
Current assignee: HEILONGJIANG PROVINCIAL PETROLEUM CHEMISTRY INST
Priority date: 2003-03-21
Filing date: 2003-03-21
Publication date: 2006-03-08
Anticipated expiration: 2023-03-21
Also published as: CN1439627A

Abstract

The present invention relates to a method for preparing isobutyl isobutyrate from isobutyraldehyde by condensation. The present invention relates to a method for preparing isobutyl isobutyrate, particularly to a method for preparing isobutyl isobutyrate in a condensation mode. The present invention uses isobutyraldehyde as a raw material, and the isobutyraldehyde is condensed into isobutyl isobutyrate under the action of a catalyst system which mainly adopts aluminium alkoxide. A reaction equation is as follows: 2C3H7CHO->C3H7COOCH2C3H7. Reaction conditions are as follows: the reaction temperature is from-30 DEG C to 20 DEG C, the reaction time is from 0.5 to 5 hours, the use level of a catalytic agent is 0.05 to 1.00g of aluminum per 100g of isobutyraldehyde, and the use level of a catalyst promoter is 0.01 to 10.00g/100 ml of the catalytic agent. The present invention solves the problems that equipment is seriously corroded by reaction media, and the price, the unit consumption and the cost of raw materials are high existing in the existing method for preparing isobutyl isobutyrate.

Description

Method for producing isobutyl isobutyrate by condensing isobutyraldehyde

The technical field is as follows: the invention relates to a method for producing isobutyl isobutyrate, in particular to a method for producing isobutyl isobutyrate by a condensation method.

Background art: traditionally, esters have been produced by esterification of alcohols with acids in the presence of acidic catalysts. Isobutyl isobutyrate is not an exception, isobutyl isobutyrate is usually prepared by esterifying isobutyric acid and isobutanol under the action of catalysts such as sulfuric acid and phosphoric acid and removing one molecule of water, a reaction medium has strong corrosivity, production equipment is made of stainless steel, and equipment cost and maintenance cost are high. The esterification method uses isobutyric acid and isobutanol as raw materials, and has higher raw material price, raw material unit consumption and raw material cost.

The invention content is as follows: in order to solve the problems of strong corrosion of a reaction medium to equipment and high raw material price, raw material unit consumption and raw material cost in the conventional method for producing isobutyl isobutyrate, the invention provides a method for producing isobutyl isobutyrate by condensing isobutyraldehyde. The method of the invention comprises the following steps: condensing isobutyric acid isobutyl ester by taking isobutyraldehyde as raw material under the action of catalyst system mainly comprising aluminum alkoxide, wherein the reaction equation is 2C₃H₇CHO→C₃H₇COOCH₂C₃H₇. The reaction conditions are as follows: the reaction temperature is-30 ℃ to 20 ℃, the reaction time is 0.5 to 5 hours, the dosage of the main catalyst is 0.05 to 1.00g of aluminum per 100g of isobutyraldehyde, and the dosage of the cocatalyst is 0.01 to 10.00g per 100ml of the main catalyst. The condensation process may employ batch, semi-continuous or multi-stage continuous reactors. The optimal reaction temperature is-10-15 ℃, the optimal reaction time is 1-3 hours, and the optimal dosage of the main catalyst is 0.1-1.0 g of aluminum per 100g of isobutyraldehyde. The condensation reaction is exothermic reaction, the condensation reactor is provided with a refrigerant heat-taking device, and the reaction can be carried out in a 2-3-stage continuous reactor for taking heat inside or outside the reactor in order to ensure the low-temperature reaction state. In any way, the temperature of each point in the reaction system should be kept uniform. The reaction mixture after the completion of the condensation reaction still contains aluminum alkoxide as a catalyst and should be separated from the reaction system. The method separates out the catalyst aluminum alcoholate in the reaction liquid by adopting the following method:adding a certain amount of water to react the aluminum alkoxide with the water so as to achieve the purpose of decomposing and destroying the catalyst, wherein the reaction equation is as follows: the amount of water added is 0.08-8.0 ml/100ml of reaction solution, and the optimal amount of water added is 0.2-5.0 ml/100ml of reaction solution. Resulting solid Al (OH)₃The solid-liquid separation is realized by an evaporation mode, and the generated alcohol is recovered in the product refining process. Al (OH) formed by the reaction of aluminum alkoxide with water₃Precipitate, particles thereofThe invention adopts evaporation mode to heat and evaporate volatile liquid phase component to make the residual effective component in solid phase escape, thus reducing product loss. The evaporated gas phase component directly enters the next rectifying tower in a saturated steam state, and the heat energy can be saved. The main catalyst provided by the invention takes aluminum alkoxide (trialkoxyaluminum) as the main component, is prepared by directly reacting alcohol with aluminum, and the alcohol which can be used for preparing the catalyst is as follows: ethanol, propanol, isopropanol, butanol or isobutanol. The simple substance aluminum does not react with the alcohol generally, and I is added₂、HgCl₂、AlCl₃、CuCl₂Or an aluminum alkoxide initiator, wherein the aluminum alkoxide can react with alcohol to generate aluminum alkoxide and release hydrogen. The reaction equation is: (ii) a In order to ensure that the reaction is smoothly carried out, isobutyl isobutyrate is used as a medium in the reaction system, alcohol is added in a dropwise manner, and the reaction is completed when no hydrogen is discharged from the reaction system, so that the prepared aluminum alkoxide catalyst has good activity after a quantitative cocatalyst is added. The cocatalyst can be added during the synthesis of the main catalyst or after the synthesis of the main catalyst. An optional compound as a cocatalyst is CaCl₂、MgCl₂、ZnCl₂Or FeCl₃. The amount of the main catalyst is 0.01-10.0 g/100ml, and the optimum amount is 0.1-2.0 g/100 ml. Aiming at the defects of the existing esterification process, the invention provides the production method for producing isobutyl isobutyrate by one-step condensation of isobutyraldehyde, which has the advantages of low raw material consumption, simple process, low cost, high product purity and no pollution of main emissions. The invention provides a shrinkCompared with the traditional esterification process, the process for legally producing isobutyl isobutyrate has obvious advantages, and is embodied in the following aspects: 1. the raw materials are reasonably utilized, isobutyraldehyde is used as the raw material in the condensation method, and isobutyric acid and isobutanol are used as the raw material in the esterification method. Isobutyric acid and isobutanol are both prepared by further processing isobutyraldehyde, and the price is higher than that of isobutyraldehyde, so the raw materials of the condensation method are far lower than that of the esterification method. 2. The condensation reaction adopted by the invention has no element loss, and the used catalyst has good activity and selectivity, and the unit consumption of raw materials is far lower than that of the esterification process. Therefore, the raw material cost of the condensation process is far lower than that of the esterification process in terms of raw material consumption, and the method brings greater economic benefits for the production of isobutyl isobutyrate. 3. The condensation process has no corrosive medium, and the production equipment can be made of common carbon steel, so that not only can the investment cost of a large amount of equipment be saved, but also the maintenance cost of the equipment during the operation of the device can be greatly reduced. 4. The process of the invention has the particularity that the product quality, the three wastes discharge and the environmental protection are greatly improved.

The first embodiment is as follows: using a 500ml three-necked flask with a stirrer and a reflux condenser, 5.0g of aluminum and 2.7g of AlCl were weighed₃And 0.63g FeCl₃And 220ml of isobutyl isobutyrate was weighed into the flask. Heating to boiling under stirring, and refluxing for 30-60 minutes. Then slowly adding 35ml of anhydrous isobutanol dropwise to make the reactionShould be carried out stably. And finishing the reaction when no hydrogen is discharged from the reaction system. The reaction solution was cooled and sealed with nitrogen gas to prepare a condensation catalyst. The condensation reactor is a 200ml glass reactor with a refrigerant jacket and is provided with a stirring temperature measuring and reflux condensing device. Two kettles are connected in series, raw material isobutyraldehyde and catalyst are continuously injected into a reactor according to the volume ratio of 8: 1, the reaction temperature is kept between 0 and 10 ℃, and the total retention time is about 100 minutes. After the reaction is balanced, the reaction solution is taken out, the content of residual isobutyraldehyde, products and byproducts in the reaction solution is determined through gas chromatography analysis, and the conversion rate of the isobutyraldehyde is calculated to be 98.2 percent, and the reaction selectivity is calculated to be 95.3 percent. Weighing 200g of condensation reaction liquid, putting into a round bottom flask with a stirrer and a condenser, adding 2ml of water, heating to boil, and condensingThe distillate was collected in the vessel, cooled after the solids in the flask had dried, and the distillate and solid residue were weighed to calculate an evaporation yield of 97.2%.

The second embodiment is as follows: except adding the same amount of aluminum and AlCl during the preparation of the catalyst₃、FeCl₃Optionally ZnCl₂0.5g, the other operations were carried out in the same manner as in the example, giving an isobutyraldehyde conversion of 98.5%, a reaction selectivity of 95.1% and an evaporation yield of 97.0%.

Claims

1. The method for producing isobutyl isobutyrate by condensing isobutyraldehyde is characterized in that isobutyraldehyde is used as a raw material and condensed into isobutyl isobutyrate under the action of an aluminum alkoxide serving as a main catalyst system, and the reaction equation is The condensation process adopts a batch type, semi-continuous type or multi-stage continuous type reactor, and the reaction conditions are as follows: the reaction temperature is-30 ℃ to 20 ℃, the reaction time is 0.5 to 5 hours, the dosage of the main catalyst is 0.05 to 1.00g of aluminum per 100g of isobutyraldehyde, and the dosage of the cocatalyst is 0.01 to 10.00g per 100ml of the main catalyst.

2. The method for producing isobutyl isobutyrate by condensing isobutyraldehyde according to claim 1, wherein the reaction is carried out in a 2-3-stage continuous reactor.

3. The method for producing isobutyl isobutyrate by condensing isobutyraldehyde according to claim 1, wherein the aluminum alkoxide as the catalyst in the reaction solution is separated by: adding a certain amount of water to react the aluminum alkoxide with the water, wherein the adding amount of the water is 0.08-8.0 ml/100ml of the reaction solution, and generating solid Al (OH)₃The solid-liquid separation is achieved by evaporation.

4. The method for producing isobutyl isobutyrate by condensing isobutyraldehyde according to claim 1, wherein the main catalyst used is prepared by directly reacting an alcohol with aluminum, and the alcohol used for preparing the main catalyst is: ethanol, propanol, ethanol, isopropanol, and ethanol,Isopropanol, butanol or isobutanol, adding an initiator during reaction, wherein the initiator is I₂、HgCl₂、AlCl₃、CuCl₂Or aluminum alkoxides.

5. The process for the production of isobutyl isobutyrate by condensation of isobutyraldehyde according to claim 1 or 4, wherein the compound selected as co-catalyst comprises CaCl₂、MgCl₂、ZnCl₂Or FeCl₃。