Method for separating methanol and methyl (meth)acrylate

Abstract

The present invention relates to a method for producing a distillation product having a methanol concentration higher than that of the minimum boiling azeotropic mixture of methanol and methyl (meth)acrylate from a mixture having a methanol concentration lower than that of the minimum boiling azeotropic mixture of methanol and methyl (meth)acrylate in a distillation column, and further relates to a method for producing a distillation product having a methanol concentration higher than that of the minimum boiling azeotropic mixture of methanol and methyl (meth)acrylate from methyl (meth)acrylate. 22 The present invention provides a transesterification process for preparing alkyl, aryl, or alkenyl (meth)acrylates of the formula:

Description

[Technical field]

[0001] FIELD OF THEINVENTION The present invention relates to a method for breaking the azeotrope of methanol and methyl (meth)acrylate, and further to a method for obtaining C 2 -(methyl)acrylate from methyl (meth)acrylate. 6 ~C 22 The present invention provides a transesterification process for preparing an alkyl, aryl, or alkenyl (meth)acrylate of the formula:

[0002] The term "breaking the azeotrope of methanol and methyl (meth)acrylate" as used in the context of the present invention refers to a process for producing a distilled product having a methanol concentration higher than the methanol concentration in the minimum boiling azeotrope of methanol and methyl (meth)acrylate from a mixture having a methanol concentration equal to or lower than the methanol concentration in the minimum boiling azeotrope of methanol and methyl (meth)acrylate in a distillation column.

[0003] 2. Background of the Invention The alkyl, aryl, or alkenyl (meth)acrylates are generally prepared by transesterification of methyl (meth)acrylate with the respective alcohol.

[0004] The transesterification of methyl (meth)acrylate with alcohols produces methanol, which is usually recovered in the form of a mixture of methanol and methyl (meth)acrylate by distillation. The resulting distillate can have a methanol concentration as high as the azeotropic composition, but is typically lower than this maximum. This leads to an undesirable loss of methyl (meth)acrylate. The distillate thus obtained must undergo additional processing steps to isolate and reuse the methyl (meth)acrylate. For economic reasons, it would be particularly desirable if the effects of azeotrope formation could be reduced, resulting in a reduced loss of methyl (meth)acrylate in the distillation product.

[0005] In view of the above, it is an object of the present invention to provide a method for breaking the methanol / methyl (meth)acrylate azeotrope, either as an independent process from the transesterification reaction or as part of an improved process for preparing alkyl, aryl, or alkenyl (meth)acrylates, respectively, by transesterification, in which the amount of methyl (meth)acrylate in the distillate is significantly reduced, thereby reducing or potentially even avoiding the additional separation steps currently required for the distillate.

[0006] Summary of the Invention For alkyl, aryl, or alkenyl (meth)acrylates having linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl groups having 6 to 22 carbon atoms, this problem is solved by the process according to the invention.

[0007] The inventors unexpectedly found that the azeotropic mixture was separated via a distillation column into each of the C 6 ~C 22 When treated with an alcohol feed stream, the methanol concentration in the distillate can exceed the azeotropic concentration of methanol (i.e., the azeotrope is broken), and methyl (meth)acrylate is reduced in the distillate stream and replaced by C. 6 ~C 22 It was found that the alcohol stream is enriched in methanol, resulting in a rapid increase in the methanol concentration in the distillate, and a methyl (meth)acrylate concentration that is significantly lower than the azeotropic concentration of methyl (meth)acrylate is reached, which significantly increases the efficiency of the process in terms of the yield of methyl (meth)acrylate.

[0008] The present invention therefore relates to a process for breaking the azeotrope of methanol and methyl (meth)acrylate in a distillation column, i.e. a process for producing a distilled product having a higher methanol concentration than the methanol concentration in the minimum boiling azeotrope of methanol and methyl (meth)acrylate from a mixture of methanol and methyl (meth)acrylate having a methanol concentration equal to or less than the methanol concentration in the minimum boiling azeotrope of methanol and methyl (meth)acrylate, the process comprising the steps of: adding a mixture of methanol and methyl (meth)acrylate having a methanol concentration equal to or less than the methanol concentration in the minimum boiling azeotrope of methanol and methyl (meth)acrylate to an alcohol feed stream of formula (I) located in the distillation column; H.O.R. 1 (I) [In the formula, R 1 is a linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl group having 6 to 22 carbon atoms. with an alcohol of

[0009] Further, the present invention relates to a compound represented by formula (II) CH 2 =C(R 2 )-CO-OR 1 (II) [In the formula, R 2 is hydrogen or methyl, R 1 is a linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl group having 6 to 22 carbon atoms. A method for preparing a (meth)acrylate of Formula (III) CH 2 =C(R 2 )-CO-OMe (III) [In the formula, R 2 is as defined above] Methyl (meth)acrylate of formula (I) H.O.R. 1 (I) [In the formula, R 1 is as defined above] by reacting with an alcohol of The present invention relates to a process in which methanol produced by the transesterification reaction is separated from the methyl (meth)acrylate of formula (III) using a distillation column at a methanol concentration equal to or less than the azeotropic composition of methanol and the methyl (meth)acrylate of formula (III); and the resulting mixture is concentrated to a methanol concentration higher than the methanol concentration in the azeotropic composition of methanol and the methyl (meth)acrylate of formula (III) by further adding an alcohol of formula (I) via an alcohol feed stream arranged in the distillation column.

[0010] The process according to the invention can be carried out batchwise or continuously.

[0011] Detailed Description of the Invention The distillation column used in the process of the invention is preferably an extractive distillation column, which, in addition to the extractive section, may further comprise a rectification section and / or a stripping section.

[0012] In one embodiment of the present invention, the extractive distillation column is divided into three sections: (1) a rectifying section between the top of the column and the alcohol feed location, (2) an extractive section between the alcohol feed location and the azeotrope feed location, and (3) a stripping section located below the azeotrope feed location.

[0013] In a different embodiment of the invention, the extractive distillation column has two sections: (1) a rectifying section between the top of the column and the alcohol feed point, and (2) an extractive section between the alcohol feed point and the azeotrope feed point.

[0014] In the process according to the invention, the alcohol feed stream is placed in the distillation column, for example at the top of the distillation column or in the top region of the distillation column.

[0015] Preferably, the alcohol feed stream is located in the top region of the distillation column. The term "top region of the distillation column" as used in the context of the present invention refers to a position in the extractive distillation column where the number of separation trays in the extractive section is equal to or greater than the number of separation trays in the rectification section.

[0016] However, feeding the alcohol to the top of the column can result in losses of the alcohol used as the extractant. Therefore, the alcohol is advantageously fed near the top of the distillation column (i.e., in the top region, see above) so that sufficient rectification occurs to avoid excessive alcohol losses while maximizing the separation capacity of the extraction section. In other words, the preferred location of the alcohol feed stream is one that provides sufficient column height for extraction.

[0017] Preferably, there are a minimum of 0.01 and a maximum of 10 theoretical separation trays above the alcohol feed stream to avoid undesirable enrichment back towards the azeotropic composition.

[0018] The alcohol of formula (I) can be added, for example, via the alcohol feed stream at a temperature between 0°C and 70°C.

[0019] The addition of the alcohol of formula (I) via the distillation column can be carried out batchwise or continuously.

[0020] To prevent the undesired polymerization of (meth)acrylates, polymerization inhibitors can be used in the processes according to the invention. Advantageously, these processes are carried out in the presence of an inhibitor composition comprising or consisting of at least one phenolic polymerization inhibitor.

[0021] These compounds, such as hydroquinone, hydroquinone ethers, such as hydroquinone monomethyl ether or di-tert-butylcatechol, phenothiazine, N,N'-(diphenyl)-p-phenylenediamine, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, p-phenylenediamine, methylene blue, or sterically hindered phenols, are widely known in the art. These compounds can be used individually or in the form of mixtures and are also widely available commercially. The mechanism of action of the stabilizer is usually to act as a free radical scavenger for the free radicals generated during polymerization. Based on the total weight of the reaction mixture, the proportion of the inhibitor, either individually or as a mixture, can usually be 0.001 to 0.5% (w / w).

[0022] These polymerization inhibitors can be added before or at the start of the reaction or distillation, respectively. Furthermore, small amounts of the polymerization inhibitors used can be introduced during the transesterification. Particularly interesting here are processes in which part of the polymerization inhibitor is added via the column reflux. Among these, it is particularly advantageous to use a mixture containing methyl (meth)acrylate, hydroquinone monomethyl ether and 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl. This measure makes it possible to avoid undesired polymerization, especially in the distillation column.

[0023] Furthermore, gaseous oxygen can also be used for inhibition. This can be used, for example, in the form of air, the amount introduced being advantageously such that the content in the gas phase above the reaction mixture remains below the limiting oxygen concentration in the explosion zone. Amounts of air in the range of 0.05-0.5 l per hour and mole of primary alcohol are particularly preferred. It is likewise possible to use inert gas / oxygen mixtures, for example nitrogen / oxygen or argon / oxygen mixtures.

[0024] In certain embodiments of the invention, a combination of oxygen and hydroquinone monomethyl ether (HQME) can be used for inhibition.

[0025] Alternatively, the process according to the invention can be carried out in the presence of an inhibitor composition comprising or consisting of a polymerization inhibitor selected from the group consisting of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl, 2,2-diphenyl-1-picrylhydrazyl, phenothiazine, N,N'-diphenyl-p-phenylenediamine, nigrosine, para-benzoquinone, and capferon, optionally in combination with a phenolic polymerization inhibitor.

[0026] In the context of the present invention, the term "alkyl, aryl, or alkenyl (meth)acrylate" is understood to mean alkyl, aryl, or alkenyl esters of both methacrylic and acrylic acid.

[0027] In the alkyl, aryl, or alkenyl (meth)acrylate of formula (II) and the alcohol of formula (I), R 1 may be selected from linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl groups having 6 to 22 carbon atoms. The term "cyclic alkyl group" refers to monocyclic or polycyclic alkyl species, and thus includes bicyclic groups such as isobornyl. Preferably, R 1 is a linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl group having 7 to 20, preferably 8 to 18, carbon atoms.

[0028] R 1 The radicals are understood to mean, for example, n-hexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl, 2-octyl, 2-ethylhexyl, nonyl, 2-methyloctyl, 2-tert-butylheptyl, 3-isopropylheptyl, decyl, undecyl, 5-methylundecyl, dodecyl, stearyl and / or behenyl radicals, and / or cycloalkyl radicals, such as cyclohexyl, tert-butylcyclohexyl, cycloheptyl, cyclooctyl, bornyl and / or isobornyl. Furthermore, R1 The group is optionally substituted (C 6 ~C 14 )-Aryl-(C 1 ~C 8 )-alkyl group, preferably (C 6 ~C 12 )-Aryl-(C 1 ~C 4 )-alkyl groups, for example benzyl, naphthylmethyl, naphthylethyl, 2-phenylethyl, 2-phenoxyethyl, 4-phenylbutyl, 3-phenylbutyl, 2-phenylbutyl, and / or 2-biphenylethyl groups.

[0029] The methyl(meth)acrylate of formula (III) can be introduced into the transesterification process according to the invention as a pure substance or as a mixture, for example with a methanol concentration below the azeotropic composition (from a previous reaction), or as a combination of a mixture of methyl(meth)acrylate of formula (III) and methanol, the mixture having a methanol concentration below the azeotropic composition of methanol and methyl(meth)acrylate of formula (III), and fresh / pure methyl(meth)acrylate of formula (III). Such a process setup is particularly suitable for a transesterification process carried out in a continuous manner.

[0030] The process according to the invention can also be realized, for example, in a single plant. Any alcohol that does not form an azeotrope with the methyl (meth)acrylate of formula (III), i.e. the alcohol of formula (I), is added via a first column to break the azeotrope. Then, in a second column, the methyl (meth)acrylate of formula (III) is separated from the alcohol of formula (I), which is then recycled to the first column.

[0031] In the batch process, the azeotrope is fed to the reactor before the alcohol, allowing it to maintain boiling under full reflux. The alcohol required for the reaction is then fed to the column. While this alcohol extracts the methyl (meth)acrylate of formula (III) from the boiling azeotrope, it also starts the transesterification reaction.

[0032] In a particularly preferred embodiment of the invention, the (meth)acrylate of formula (II) is 2-ethylhexyl methacrylate, the methyl (meth)acrylate of formula (III) is methyl methacrylate and the alcohol of formula (I) is 2-ethylhexanol.

[0033] The molar ratio of the alcohol of formula (I) to the methyl (meth)acrylate of formula (III) fed to the transesterification reactor is preferably in the range of 10:1 to 1:10, more preferably 1:1 to 1:5, and most preferably 1:1.1 to 1:2.5, the latter ratio being particularly suitable for continuous transesterification processes.

[0034] In a preferred embodiment of the invention, after the initial reaction period, an additional amount (or remaining equivalents) of alcohol (I) is introduced into the reaction mixture via a distillation column to concentrate the methanol to a concentration higher than that in the azeotrope.

[0035] The addition of alcohol (I) via the distillation column can begin immediately after the start of the transesterification or can begin after the reaction has reached steady state. In a batch process, the feed of alcohol to the distillation column can begin at the beginning of the batch or at some point after the batch.

[0036] To catalyze the transesterification, alkyl titanates (e.g., tetraisopropyl titanate, tetrakis(ethylhexyl) titanate), zirconium acetylacetonate, dialkyltin compounds, lithium compounds (e.g., lithium oxide, lithium hydroxide, lithium chloride, lithium amide (LiNH 2), lithium alcoholates (preferably LiOMe), calcium compounds (e.g., calcium oxide and calcium hydroxide), or acids (e.g., p-toluenesulfonic acid, sulfuric acid, methanesulfonic acid), can be used alone or in any combination of the aforementioned catalysts.

[0037] Particularly suitable catalysts are, for example, tetraisopropyl titanate, tetrakis(ethylhexyl) titanate, and zirconium acetylacetonate. The catalysts can be purchased in a ready-to-use form or can be prepared in situ. Alternatively, the catalysts can be obtained by recycling from downstream processing.

[0038] Advantageously, it is possible to use between 0.2 and 10 mmoles, and better still between 0.5 and 8 mmoles, of catalyst per mole of alcohol of formula (I).

[0039] The reaction times depend, inter alia, on the selected parameters, such as pressure and temperature. However, they are usually in the range of 1 to 24 hours, preferably 5 to 20 hours, very particularly preferably 6 to 18 hours. In the case of a continuous process, the reactor residence time is usually in the range of 1 to 24 hours, preferably 2 to 20 hours, very particularly preferably 2.5 to 10 hours.

[0040] The reaction can preferably be carried out with stirring, the stirring speed being particularly preferably in the range from 50 to 2000 rpm, very particularly preferably in the range from 100 to 500 rpm.

[0041] A suitable plant for carrying out the transesterification may be, for example, a stirred tank reactor equipped with a stirrer, a steam heater, a distillation column (azeotropic column) and a condenser. The size of the plant depends on the amount of alkyl (meth)acrylate to be produced, and the process according to the invention can be carried out either on laboratory scale (reactor volume 0.5-20 liters) or, particularly advantageously, on industrial scale. Thus, in a particular embodiment, the stirred tank reactor is a 0.25 m 3~50m 3 , preferably 1m 3 ~50m 3 , more preferably 3m 3 ~25m 3 The reactor tank may have a tank volume in the range of 1000 to 2000 mm. The agitator of the reactor tank may be configured in the form of an anchor agitator, an impeller, a paddle agitator, or an INTERMIG® agitator, among others.

[0042] A distillation column (azeotropic column) can have one, two or more separation stages, where the number of separation stages refers to the number of trays in a tray column, or the number of theoretical stages in the case of structured or randomly packed columns.

[0043] Examples of multi-stage distillation columns having trays include those having bubble cap trays, sieve trays, tunnel cap trays, valve trays, slot trays, slot sieve trays, bubble cap sieve trays, jet trays, centrifugal trays, and the like.

[0044] Examples of multi-stage distillation columns with random packing are those with Raschig rings, Raschig Super rings, Lessing rings, Pall rings, Berl saddles, Intalox saddles, etc.; examples of multi-stage rectification columns with structured packing are those of Mellapak type (Sulzer), MellapakPlus, Rombopak type (Kuehni), Montz-Pak type (Montz), etc. Preferably, there are a minimum of 0.01 and a maximum of 10 theoretical separation trays above the alcohol feed stream to avoid undesired enrichment back towards the azeotropic composition.

[0045] It is also possible to use distillation columns having different internal combinations, for example having structured packing in a first column section and trays or random packing in a second column section.

[0046] After the reaction is completed, the alkyl (meth)acrylate obtained in most cases already meets the general requirements of each alkyl (meth)acrylate product, so in most cases no further purification is required.However, after the reaction is completed, the product can also be isolated by distillation.

[0047] To further improve the quality, the mixture obtained can be purified by known processes, in particular to remove the catalyst. Due to the tendency of the monomers to polymerize, it is advisable to adopt a distillation process that minimizes the thermal stress on the material to be distilled. Very suitable apparatus are those in which the monomers evaporate continuously from a thin layer, such as falling film evaporators or evaporators with a rotating wiper system. Short-path evaporators can also be used. The distillation can be carried out, for example, using a continuous evaporator with a rotating wiper system and an attached column. This distillation can be carried out, for example, at pressures in the range of 1 to 60 mbar and evaporator temperatures of 60 ° C to 130 ° C (surface temperature of wiped film evaporators).

[0048] Hereinafter, the present invention will be illustrated by non-limiting examples and exemplary embodiments.

[0049] Working Example: Comparative Example 1: In a continuous transesterification system consisting of a reactor equipped with an azeotropic column and an additional column for the work-up of the continuously withdrawn reactor crude product, where the unreacted feedstock is separated and recycled, the reactor is continuously fed with alcohol, MMA and catalyst (titanium (IV) alkoxide). The reactants were introduced into the reactor. In this example, 2-ethylhexanol was used as the alcohol. Methanol produced by the reaction conversion is continuously withdrawn from the reactor in the form of a mixture containing methanol at a concentration below the azeotropic concentration of methanol, via the azeotropic column. To evaluate the concentration during operation, the density of the distillate is measured and recorded in real time and used to calculate the ratio of methanol to MMA (from the temperature-corrected density of the pure substances). As a result of the thermodynamic limit to the separation performance due to the azeotropic mixture, the concentration at the top of the column is typically 78% by weight of methanol. After reaching a steady state, a sample of the recovered methanol distillate was withdrawn and analyzed. The results are reported in Table 1.

[0050] Example 1: In a continuous transesterification system consisting of a reactor equipped with an azeotropic column and an additional column for the work-up of the continuously withdrawn reactor crude product, in which the unreacted feedstock is separated and recycled, the reactor is continuously fed with alcohol, MMA and a catalyst (titanium (IV) alkoxide). The reactants were introduced into the reactor and the alcohol feed point was moved to a position near the top of the azeotropic column without preheating the alcohol. The temperature of the alcohol was 20°C. A structured packing element with a theoretical separation power of about 0.8 trays is placed above the alcohol feed point. In this example, 2-ethylhexanol was used as the alcohol. Methanol produced by the reaction conversion is continuously withdrawn from the reactor in the form of a mixture containing methanol at a concentration lower than the azeotropic concentration of methanol through the azeotropic column. To evaluate the concentration during operation, the density of the distillate is measured and recorded in real time and used to calculate the ratio of methanol to MMA (from the temperature-corrected density of the pure substances). The reactor was started up according to Comparative Example 1 and allowed to reach a steady state, after which the alcohol feed point was changed as described above. The methanol concentration in the distillate clearly reacts to the change in the feed point within 2 minutes, and the collected methanol distillate is estimated to have a methanol concentration of more than 78% by weight. After 30 minutes, with a calculated methanol concentration of 90% by weight, the first sample of the distillate is taken; the analytical results are almost the same. After 2 hours, the second sample with a calculated purity of 93% by weight contains an analytical content of 92.7% by weight of methanol, and after 4 hours, when the steady state of 94.5% by weight of methanol is reached, the third sample contains an analytical content of 93.25% by weight of methanol. Depending on the concentration of methanol in the distillate, the total amount of distillate withdrawn is reduced. With the reduction in the concentration of MMA withdrawn in the azeotrope, the feed flow of MMA to the reactor is reduced after the steady state is reached. The temperature at the top of the column does not change. At the bottom vapor inlet of the column, the temperature is reduced by 20°C from 94°C to 74°C. The differential pressure in the column is unchanged.

[0051] [Table 1]

[0052] Example 2: In a V=3 L glass flask equipped with a stirrer, an electric heating mantle, a mirror-surfaced randomly packed column (bottom height=0.3 m, diameter=45 mm, top height=0.7 m, diameter=30 mm), a condenser and a reflux distributor, 1.8 kg of a mixture of 75% by weight MeOH and 25% by weight MMA is initially placed. In addition, air is blown into the reactor contents at 2 NL / h. The mixture is stabilized with 1000 ppm (by weight) HQME and 50 ppm (by weight) Tempol (4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl). Thermocouples for monitoring the temperature are placed both in the flask and at the top of the column. The mixture in the flask is heated to boiling, with a ratio of reflux at the top of the column:distillate withdrawn through the reflux distributor of 1:1. After a stable overhead temperature is reached, the collected distillate is sampled and analyzed by GC.

[0053] After an additional 15 minutes, 8 g / min of 2-ethylhexanol is added to the top of the column at reflux using an HPLC pump and Coriolis mass flowmeter. The resulting distillate is again sampled and analyzed after 10 and 45 minutes. The 1:1 reflux: withdrawn distillate ratio remains unchanged.

[0054] Example 3: The procedure is the same as in Example 2, except that 7 g / min of i-decyl alcohol is added as the alcohol.

[0055] Example 4: The procedure is the same as in Example 2, except that the alcohol added is 6 g / min of C13.0 alcohol (Lorol Spezial).

[0056] Example 5: The procedure is the same as in Example 2, but with the addition of 7 g / min of cyclohexanol as the alcohol.

[0057] Comparative Example 2: The procedure is the same as in Example 2, but with the addition of 7.3 g / min of n-BuOH as the alcohol.

[0058] The results of the distillate analysis of the experiments are summarized in Table 2.

[0059] [Table 2]

[0060] It is clear that without the addition of alcohol at the top of the column, a composition close to the azeotropic composition of MMA and MeOH (approximately 85.5 wt % MeOH and 14.5 wt % MMA at 1013 mbar) is obtained (see reference without added alcohol).

[0061] In contrast, alcohols with sufficiently low polarity (e.g., C n H 2n+1 -OH, n ≥ 6; C n H 2n-1 -OH, n ≥ 6, or C n H 2n-7 -OH, n ≥ 6) selectively extracts MMA from the mixture of methanol and MMA into the bottom of the column, resulting in a further concentration of methanol since the methanol concentration exceeds the azeotropic concentration of methanol.

[0062] In contrast, the more polar short chain alcohol (Comparative Example 2) does not produce a distillation product having a methanol concentration higher than that in the minimum boiling azeotrope of methanol and methyl methacrylate.

Claims

1. 1. A process for producing a distilled product having a methanol concentration higher than the methanol concentration in a minimum boiling azeotrope of methanol and methyl (meth)acrylate from a mixture of methanol and methyl (meth)acrylate having a methanol concentration equal to or less than the methanol concentration in said minimum boiling azeotrope of methanol and methyl (meth)acrylate in a distillation column, comprising: A mixture of methanol and methyl (meth)acrylate having a methanol concentration equal to or less than the methanol concentration in said minimum boiling azeotrope of methanol and methyl (meth)acrylate is added via an alcohol feed stream located in a distillation column, HO-R １ (I) [In the formula, R １ is a linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl group having 6 to 22 carbon atoms.

5. A method according to claim 1, comprising the step of contacting said carboxylic acid with an alcohol of formula (I).

2. 2. The process according to claim 1, characterized in that the distillation column used is an extractive distillation column having at least an extractive section and a rectifying section, and in that the alcohol feed stream is arranged in the extractive distillation column such that the number of separation trays in the extractive section is equal to or greater than the number of separation trays in the rectifying section.

3. 3. The process according to claim 1 or 2, characterized in that there are a minimum of 0.01 and a maximum of 10 theoretical separation trays above the alcohol feed stream.

4. 3. The process according to claim 1 or 2, characterized in that the alcohol of formula (I) is added via the alcohol feed stream at a temperature between 0°C and 70°C.

5. 3. The process according to claim 1 or 2, characterized in that it is carried out batchwise or continuously.

6. Formula (II) CH ２ =C(R ２ )-CO-OR １ (II) [In the formula, R ２ is hydrogen or methyl, R １ is a linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl group having 6 to 22 carbon atoms. A process for preparing a (meth)acrylate of Formula (III) CH ２ =C(R ２ )---OMe (---) [In the formula, R ２ is as defined above. Methyl (meth)acrylate of formula (I) HO-R １ (I) [In the formula, R １ is as defined above. by reacting with an alcohol of The methanol produced by the transesterification reaction is separated from the methyl (meth)acrylate of formula (III) using a distillation column at a methanol concentration equal to or less than the azeotropic composition of methanol and the methyl (meth)acrylate of formula (III); The resulting mixture is concentrated to a methanol concentration higher than the methanol concentration in the azeotropic composition of methanol and the methyl (meth)acrylate of formula (III) by further adding the alcohol of formula (I) via an alcohol feed stream disposed in the distillation column. method.

7. and / or characterized in that the distillation column used is an extractive distillation column having at least an extractive section and a rectifying section, and in that the alcohol feed stream is arranged in the extractive distillation column such that the number of separation trays in the extractive section is equal to or greater than the number of separation trays in the rectifying section; 7. The method of claim 6, wherein there are a minimum of 0.01 and a maximum of 10 theoretical separation trays above the alcohol feed stream.

8. 8. The process according to claim 6 or 7, characterized in that it is carried out batchwise or continuously.

9. 8. The process according to claim 6 or 7, characterized in that the addition of the alcohol of formula (I) via the distillation column is started after the reaction has reached a steady state.

10. the methyl (meth)acrylate of formula (III) is introduced into the transesterification reaction as a mixture of the methyl (meth)acrylate of formula (III) and methanol; the mixture has a methanol concentration less than or equal to the azeotropic composition of methanol and the methyl (meth)acrylate of formula (III); The mixture is obtained from a prior transesterification reaction with methanol formation. or The methyl (meth)acrylate of formula (III) is introduced into the transesterification reaction as a combination of a mixture of the methyl (meth)acrylate of formula (III) and methanol, and the methyl (meth)acrylate of formula (III), The mixture has a methanol concentration equal to or less than the azeotropic composition of methanol and the methyl (meth)acrylate of formula (III).

8. The method according to claim 6 or 7, characterized in that

11. In the (meth)acrylate of formula (II) and the alcohol of formula (I), R １ 8. The method according to claim 6 or 7, characterized in that is a linear or branched, acyclic or cyclic alkyl, aryl, or alkenyl group having from 7 to 20 carbon atoms.

12. 8. The method according to claim 6 or 7, characterized in that the (meth)acrylate of formula (II) is 2-ethylhexyl methacrylate, the methyl (meth)acrylate of formula (III) is methyl methacrylate, and the alcohol of formula (I) is 2-ethylhexanol.

13. 8. A process according to claim 6 or 7, characterized in that the alcohol of formula (I) is added at a temperature between 0°C and 70°C.

14. 8. The process of claim 6 or 7, characterized in that the transesterification is carried out in the presence of a catalyst, the catalyst being selected from the group consisting of alkyl titanates, zirconium acetylacetonates, dialkyltin compounds, lithium compounds, calcium compounds, or combinations thereof; the catalyst being present in an amount of 0.2 to 10 millimoles per mole of the alcohol of formula (I).

15. the transesterification process is carried out in the presence of an inhibitor composition comprising or consisting of at least one phenolic polymerization inhibitor; 8. The method of claim 6 or 7, wherein the phenolic polymerization inhibitor is hydroquinone, hydroquinone monomethyl ether, or a combination thereof.