JP6132570B2 - Method for producing (meth) acrylic acid ester - Google Patents

Description

  The present invention relates to a method for producing a (meth) acrylic acid ester. More specifically, the present invention can use methyl (meth) acrylate efficiently when producing (meth) acrylic acid ester by a transesterification method using methyl (meth) acrylate as a raw material ( The present invention relates to a method for producing a (meth) acrylic acid ester. The (meth) acrylic acid ester is a compound useful as a raw material for, for example, a (meth) acrylic resin, a surfactant, an adhesive, or a paint, although depending on the type.

  In the present specification, “methyl (meth) acrylate” means “methyl acrylate” and / or “methyl methacrylate”. “(Meth) acrylic acid ester” means “acrylic acid ester” and / or “methacrylic acid ester”.

  As a method for efficiently separating methanol from a mixture of methyl (meth) acrylate and methanol using a reactor having a distillation column, an azeotropic solvent that forms an azeotrope with methanol is used, and distillation is performed from the top of the distillation column. A part of the vapor condensate is refluxed to the distillation column, the remaining condensate is separated into two layers, the separated upper layer is supplied to the middle stage of the distillation column, and the lower layer is taken out of the distillation column. A method for recovering methyl (meth) acrylate from the bottom has been proposed (see, for example, Patent Document 1).

  However, according to the method, methyl (meth) acrylate present at the bottom of the reactor can be recovered, but after the methyl (meth) acrylate is recovered, it remains in the reactor. It is not possible to recover the methyl (meth) acrylate.

  In addition, as a method of producing the target (meth) acrylic acid ester by transesterification of the raw material (meth) acrylic acid alkyl ester and alcohol, an azeotropic solvent that forms an azeotropic composition with the by-produced alkyl alcohol is used. When the transesterification reaction is carried out in the presence, the by-product alkyl alcohol is removed from the distillation outlet at the top of the distillation column together with the azeotropic solvent, and the temperature of the vapor distilled from the distillation outlet is azeotroped with the by-produced alkyl alcohol. The boiling point of the azeotropic solvent is not less than the azeotropic temperature of the azeotropic solvent and not more than 2 ° C higher than the azeotropic temperature, and the bottom temperature of the distillation column is not less than 10 ° C lower than the boiling point of the azeotropic solvent. A method for producing a (meth) acrylic acid ester has been proposed (see, for example, Patent Document 2).

  According to the method for producing the (meth) acrylic acid ester, it is said that the Michael addition reaction as a side reaction can be suppressed and the (meth) acrylic acid ester can be produced with high productivity. However, after producing the target (meth) acrylic acid ester, the raw material (meth) acrylic acid alkyl ester remains in the reaction system, and the remaining raw material (meth) acrylic acid alkyl ester A method that can efficiently recover the gas is not studied.

  Therefore, in the method of producing (meth) acrylic acid ester by transesterification using methyl (meth) acrylate as a raw material, the desired (meth) acrylic acid ester is produced and then remains in the reaction system. Development of a method for producing (meth) acrylic acid esters by transesterification that can efficiently recover methyl (meth) acrylate as a raw material is desired.

Japanese Patent Laid-Open No. 8-2688938 JP 2004-189650 A

  This invention is made | formed in view of the said prior art, In the method of manufacturing (meth) acrylic acid ester by the transesterification method, using (meth) acrylic-acid methyl as a raw material, the target (meth) acrylic is made | formed. It is an object to provide a method for producing a (meth) acrylate ester by a transesterification method capable of efficiently recovering methyl (meth) acrylate as a raw material remaining in a reaction system after producing an acid ester And

The present invention
(1) Using methyl (meth) acrylate as a raw material and subjecting the methyl (meth) acrylate to an alcohol corresponding to the target (meth) acrylic ester, the target (meth) A method for producing an acrylate ester, wherein a reactor having a distillation tower is used as a reactor, and methyl (meth) acrylate and an alcohol corresponding to the target (meth) acrylate ester are contained in the reactor. In the transesterification reaction, the solvent azeotropes with the methyl alcohol at a temperature below the boiling point of methyl alcohol and azeotropes with the methyl (meth) acrylate at a temperature below the boiling point of methyl (meth) acrylate. Using a solvent, extract methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylic ester. After Le exchange reaction, the reaction mixture in the reactor was further heated at a temperature of 70 to 140 ° C., and wherein the retrieving the steam containing (meth) acrylate unreacted from the top of the distillation column (Meth) acrylic acid ester production method,
(2) The method for producing a (meth) acrylic acid ester according to (1), wherein the azeotropic solvent is at least one selected from the group consisting of cyclohexane and n-hexane,
(3) During the transesterification reaction between methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylic ester, the vapor is taken out from the upper part of the distillation column, and the vapor taken out is condensed and obtained. The temperature of the upper part of the distillation column is adjusted to the azeotropic temperature of the alcohol and the azeotropic solvent by removing a part of the condensate to the distillation column and removing the remainder of the condensate from the reaction apparatus. ) Or (2) a process for producing a (meth) acrylic acid ester,
(4) (Meta) according to (3), wherein water is added to the condensate removed to the outside of the reaction apparatus, the upper layer and the lower layer are separated into two layers, and the upper layer of the separated two layers is refluxed to the distillation column. A method for producing an acrylic ester,
(5) Water is added to the condensate removed to the outside of the reaction apparatus, the upper layer and the lower layer are separated into two layers, and the lower layer of the separated two layers is further placed in a distillation apparatus having a distillation tower and distilled ( The (3) or (3) above, wherein a vapor containing methyl acrylate, methyl alcohol by-produced as a by-product and an azeotropic solvent, and a vapor mainly containing methyl alcohol by-produced by transesterification are taken out from the top of the distillation column (4) (meth) acrylic acid ester production method according to
(6) The vapor containing methyl methacrylate (meth) acrylate, by-produced methyl alcohol and an azeotropic solvent is used as a raw material in the transesterification reaction between methyl (meth) acrylate and the alcohol. (7) After the transesterification reaction between (meth) acrylic acid ester and (7) methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylic acid ester, the reaction mixture is further heated. Vapor containing unreacted methyl (meth) acrylate taken out from the upper part of the distillation column is condensed, and the resulting condensate is used as a raw material in the transesterification reaction between methyl (meth) acrylate and the alcohol. It is related with the manufacturing method of the (meth) acrylic acid ester in any one of said (1)-(6) to be used.

  According to the method for producing a (meth) acrylic acid ester of the present invention, in the method for producing a (meth) acrylic acid ester by a transesterification method using methyl (meth) acrylate as a raw material, After the production of the acid ester, an excellent effect is obtained that the raw material methyl (meth) acrylate remaining in the reaction system can be efficiently recovered.

  (Meth) acrylic acid methyl is a temperature-sensitive compound and polymerizes easily, so that (meth) acrylic remaining in the reactor is used to suppress the polymerization of the methyl (meth) acrylate. As a method for recovering methyl acid, a method of recovering methyl (meth) acrylate by distillation under reduced pressure at a low temperature can be considered.

  However, when methyl (meth) acrylate is recovered by distillation under reduced pressure at low temperature, the boiling point of methyl (meth) acrylate is low and the vapor pressure of methyl (meth) acrylate is high, so methyl (meth) acrylate It is difficult to capture the vapor with a condenser, and the vapor is scattered in the atmosphere, so that not only the methyl (meth) acrylate cannot be recovered efficiently but also the malodor due to the methyl (meth) acrylate May occur. Therefore, it is conceivable to arrange an exhaust gas treatment device in the condenser so that the vapor of methyl (meth) acrylate is not diffused into the atmosphere. However, when an exhaust gas treatment device is used, there are secondary problems such as the treatment of waste liquid generated in the exhaust gas treatment device, the increase in equipment costs and maintenance costs due to the use of the exhaust gas treatment device. Occur.

  Therefore, the present inventors conducted extensive research and as a result, azeotropically azeotroped with the methyl alcohol at a temperature below the boiling point of methyl alcohol as a solvent, and the (meth) acrylic at a temperature below the boiling point of methyl (meth) acrylate. Using an azeotropic solvent that azeotropes with methyl acid, transesterification of methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylic acid ester is conducted, and then the resulting reaction mixture is heated and reacted. When methyl (meth) acrylate present in the apparatus is azeotroped with the azeotropic solvent, it remains in the reaction apparatus without taking the pressure reduction operation as described above (meth). It has been found that methyl acrylate can be efficiently recovered from the reactor under normal pressure. Furthermore, the recovered methyl (meth) acrylate is a methyl (meth) acrylate as a raw material when transesterification of methyl (meth) acrylate and alcohol corresponding to the target (meth) acrylic ester is newly performed. It was also found that it can be used as

  Thus, according to the method for producing a (meth) acrylic acid ester of the present invention, the methyl (meth) acrylate remaining in the reaction apparatus is not required to be depressurized even at normal pressure. Since it can be efficiently recovered and the recovered methyl (meth) acrylate can be reused, the method for producing the (meth) acrylic acid ester of the present invention is a method with excellent industrial productivity. is there.

  As described above, the method for producing a (meth) acrylic ester of the present invention uses methyl (meth) acrylate as a raw material, and corresponds to the methyl (meth) acrylate and the target (meth) acrylic ester. This is a method for producing a target (meth) acrylic acid ester by transesterification with alcohol, and using a reaction apparatus having a distillation tower as a reaction apparatus, methyl (meth) acrylate and When transesterifying the alcohol corresponding to the target (meth) acrylic acid ester, it azeotropes with the methyl alcohol as a solvent at a temperature below the boiling point of methyl alcohol, and below the boiling point of methyl (meth) acrylate. Using an azeotropic solvent that azeotropes with the methyl (meth) acrylate at a temperature, the target with methyl (meth) acrylate After the ester exchange reaction with the alcohol corresponding to the (meth) acrylate ester, the obtained reaction mixture is further heated, and the vapor containing unreacted methyl (meth) acrylate is taken out from the upper part of the distillation column. It is characterized by.

  In the present invention, when transesterifying the methyl (meth) acrylate with the alcohol corresponding to the target (meth) acrylic ester, a reaction apparatus having a distillation column is used.

  Examples of the reaction apparatus having a distillation column include a reaction apparatus having a distillation column such as a rectification column, a fluidized bed, a fixed bed, and a reactive distillation column. However, the present invention is limited only to such examples. is not. There is no particular limitation on the structure and type of the distillation column. Among the distillation towers, those having high gas-liquid contact efficiency are preferred. Suitable distillation columns include, for example, a packed column distillation column and a tray type distillation column. The number of theoretical columns of the distillation column is preferably 7 or more from the viewpoint of efficiently and stably proceeding the transesterification reaction between methyl (meth) acrylate and the alcohol corresponding to the target (meth) acrylate ester. Preferably, it is 10 steps or more, more preferably 15 steps or more. From the viewpoint of improving economy, it is preferably 100 steps or less, more preferably 70 steps or less, and even more preferably 50 steps or less.

  The transesterification reaction of alcohol corresponding to methyl (meth) acrylate and the desired (meth) acrylic acid ester may be carried out by either a flow system or a batch system.

  In the present invention, first, methyl (meth) acrylate and an alcohol corresponding to the target (meth) acrylic ester are transesterified.

  The alcohol used for the transesterification reaction between methyl (meth) acrylate and alcohol is appropriately selected according to the intended (meth) acrylic acid ester. More specifically, an alcohol that forms an ester group of the target (meth) acrylic acid ester is used as the alcohol. As an example, for example, when the target (meth) acrylic acid ester is n-propyl (meth) acrylate, n-propyl alcohol is used as the alcohol that forms the propyl group.

  Examples of the alcohol corresponding to the target (meth) acrylic acid ester include ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and n-pentyl. Alcohol, n-hexyl alcohol, isohexyl alcohol, cyclohexyl alcohol, 3,3,5-trimethylcyclohexyl alcohol, 4-tert-butylcyclohexyl alcohol, n-heptyl alcohol, n-octyl alcohol, isooctyl alcohol, 2-ethylhexyl Alcohol, 3,4-dimethylhexyl alcohol, 3,4-dimethylheptyl alcohol, lauryl alcohol, nonyl alcohol, isononyl alcohol, Allyl alcohol, expressions such as 2-heptyl undecanoic-1-ol (I):

(Wherein R ¹ represents an alkyl group which may have a ring structure having 2 to 30 carbon atoms)
Aliphatic or alicyclic alcohol represented by: aromatic alcohol such as phenol, benzyl alcohol, 1-phenylethyl alcohol, 2-phenylethyl alcohol, phenoxyethanol; dimethylaminoethyl alcohol, diethylaminoethyl alcohol, dipropylaminoethyl alcohol, Dibutylaminoethyl alcohol, dipentylaminoethyl alcohol, dihexylaminoethyl alcohol, dioctylaminoethyl alcohol, methylethylaminoethyl alcohol, methylpropylaminoethyl alcohol, methylbutylaminoethyl alcohol, methylhexylaminoethyl alcohol, ethylpropylaminoethyl alcohol, Ethylbutylaminoethyl alcohol, ethylpentylaminoethyl alcohol , Ethyl octyl aminoethyl alcohol, propyl butyl aminoethyl alcohol, dimethylaminopropyl alcohol, diethylamino propyl alcohol, dipropylamino propyl alcohol, dibutyl aminopropyl alcohol, expressions such as butyl pentyl amino propyl alcohol (II):

(Wherein R ² and R ³ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ⁴ represents an alkylene group having 1 to ⁴ carbon atoms)
2-methoxyethyl alcohol, ethoxyethyl alcohol, butoxyethyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether (ethyl carbitol), triethylene glycol monomethyl ether, tetrahydrofurfuryl alcohol, 2-ethyl 2-methyl-1,3-dioxolane-4-methyl alcohol, cyclohexanespiro-2-1,3-dioxolane-4-methyl alcohol, 3-ethyl-3-oxetanylmethyl alcohol, 3-ethyl-3-oxetanylmethyl Alkoxy alcohols such as alcohols; monohydric alcohols such as allyl alcohol, methallyl alcohol, tetrahydrofurfuryl alcohol; ethylene glycol, 2,3-pro Dihydric alcohols such as diol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, cyclohexanediol; polyhydric alcohols having three or more hydroxyl groups such as glycerin, etc. However, the present invention is not limited to such examples. These alcohols may be used alone or in combination of two or more.

  The amount of methyl (meth) acrylate per hydroxyl group equivalent of the alcohol corresponding to the target (meth) acrylate ester is from the viewpoint of increasing the reaction rate of the transesterification reaction between methyl (meth) acrylate and the alcohol. , Preferably 0.3 equivalents or more, more preferably 0.5 equivalents or more, still more preferably 0.8 equivalents or more, and preferably 5 equivalents from the viewpoint of reducing the amount of unreacted methyl (meth) acrylate. Hereinafter, it is preferably 4 equivalents or less, more preferably 3 equivalents or less.

  A transesterification catalyst can be used when transesterifying the methyl (meth) acrylate with the alcohol corresponding to the target (meth) acrylic ester.

  Examples of the transesterification catalyst include lithium hydroxide, sodium hydroxide, potassium hydroxide, cesium hydroxide, magnesium hydroxide, calcium hydroxide, barium hydroxide, strontium hydroxide and the like; lithium hydrogen carbonate, carbonic acid Hydrogen carbonate compounds such as sodium hydrogen carbonate, potassium hydrogen carbonate, cesium hydrogen carbonate, magnesium hydrogen carbonate, calcium hydrogen carbonate, barium hydrogen carbonate, strontium hydrogen carbonate; lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, Carbonates such as barium carbonate and strontium carbonate; acetates such as lithium acetate, sodium acetate, potassium acetate, cesium acetate, magnesium acetate, calcium acetate, barium acetate and strontium acetate; lithium borohydride, Boron hydride compounds such as sodium borohydride, potassium borohydride, cesium borohydride; lithium stearate, sodium stearate, potassium stearate, cesium stearate, magnesium stearate, calcium stearate, barium stearate, stearic acid Stearates such as strontium; phenyl phenyl boron compounds such as lithium phenyl borohydride, sodium phenyl borohydride, potassium phenyl borohydride, cesium borohydride; lithium benzoate, sodium benzoate, potassium benzoate, cesium benzoate, etc. Benzoates; hydrogen phosphate compounds such as dilithium hydrogen phosphate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, and cesium hydrogen phosphate; Phenyl phosphate compounds such as disodium nyl phosphate, dipotassium phenyl phosphate, and cesium phenyl phosphate; metal alkoxides such as sodium alkoxide and titanium alkoxide; tetramethoxy titanium, tetraethoxy titanium, tetrapropoxy titanium, tetrabutoxy titanium, etc. Tetraalkoxy titanium; dialkyl tin oxide such as dialkyl tin oxide having 4 to 18 carbon atoms in the alkyl group such as dibutyl tin oxide, dioctyl tin oxide, dilauryl tin oxide; titanium alcoholate, aluminum alcoholate, magnesium alcoholate Although metal alcoholate etc. are mentioned, this invention is not limited only to this illustration. These transesterification catalysts may be used alone or in combination of two or more. Among these transesterification catalysts, from the viewpoint of promoting the transesterification reaction, tetraalkoxytitanium and dialkyltin oxide having 4 to 12 carbon atoms in the alkyl group are preferable, and tetraalkoxytitanium and alkyl groups having 4 to 4 carbon atoms. More preferred are 8 dialkyltin oxides, and tetramethoxytitanium, dibutyltin oxide and dioctyltin oxide are even more preferred.

  Since the amount of the transesterification catalyst varies depending on the type of the transesterification catalyst and cannot be determined unconditionally, it is preferably determined as appropriate according to the type of the transesterification catalyst. Usually, the amount of the transesterification catalyst per 1 mol of methyl (meth) acrylate is preferably 0.00001 mol or more, more preferably from the viewpoint of efficiently proceeding the transesterification reaction between methyl (meth) acrylate and alcohol. Is 0.0001 mol or more, and is preferably 0.10 mol or less, more preferably 0.05 mol or less, from the viewpoint of improving economy.

  Moreover, when carrying out transesterification of methyl (meth) acrylate and alcohol, a polymerization inhibitor can be used. Examples of the polymerization inhibitor include 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-acetamino-2,2,6,6-tetramethylpiperidine-N-oxyl, 4- Benzoyloxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl, 2,2,6,6-tetramethylpiperidine N-oxy radical compounds such as -N-oxyl; paramethoxyphenol, 2,2'-methylenebis (4-ethyl-6-tert-butylphenol), 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butyl-N, N-dimethylamino-p-cresol, 2,4-dimethyl-6-tert-butylphenol, 4 phenolic compounds such as tert-butylcatechol, 4,4′-thio-bis (3-methyl-6-tert-butylphenol), 4,4′-butylidene-bis (3-methyl-6-tert-butylphenol); Quinone compounds such as methoquinone, hydroquinone, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylhydroquinone, benzoquinone; copper dialkyldithiocarbamates such as cuprous chloride and copper dimethyldithiocarbamate; phenothiazines N, N′-diphenyl-p-phenylenediamine, phenyl-β-naphthylamine, N, N′-di-β-naphthyl-p-phenylenediamine, N-phenyl-N′-isopropyl-p-phenylenediamine, etc. Amino compounds; 1,4-dihydroxy-2 Examples include hydroxyamine compounds such as 2,6,6-tetramethylpiperidine, 1-hydroxy-2,2,6,6-tetramethylpiperidine, 4-hydroxy-2,2,6,6-tetramethylpiperidine. However, the present invention is not limited to such examples. These polymerization inhibitors may be used alone or in combination of two or more.

  The amount of the polymerization inhibitor per 100 parts by mass of methyl (meth) acrylate is preferably 0.00001 parts by mass or more, from the viewpoint of suppressing polymerization of methyl (meth) acrylate as a raw material and alkyl acrylate produced. More preferably it is 0.00005 parts by mass or more, more preferably 0.0001 parts by mass or more, and from the viewpoint of increasing the purity of the (meth) acrylic acid ester to be produced, it is preferably 0.1 parts by mass or less, more preferably 0. 0.05 parts by mass or less, more preferably 0.01 parts by mass or less.

  When transesterifying the methyl (meth) acrylate with the alcohol corresponding to the desired (meth) acrylic ester in the reaction apparatus, the solvent is azeotroped with the methyl alcohol at a temperature below the boiling point of methyl alcohol. An azeotropic solvent that azeotropes with the methyl (meth) acrylate at a temperature lower than the boiling point of the methyl (meth) acrylate is used. In the present invention, as described above, the solvent azeotropes with the methyl alcohol at a temperature below the boiling point of methyl alcohol and azeotropes with the methyl (meth) acrylate at a temperature below the boiling point of methyl (meth) acrylate. Since an azeotropic solvent is used, the methyl (meth) acrylate and the alcohol corresponding to the target (meth) acrylate ester are transesterified and then exist in the reactor (meth). Methyl acrylate can be efficiently recovered from the reactor.

  In addition, the said methyl alcohol is alcohol byproduced when transesterifying the (meth) acrylic acid methyl and the alcohol corresponding to the target (meth) acrylic acid ester.

  As an azeotropic solvent that azeotropes with the methyl alcohol at a temperature below the boiling point of methyl alcohol and azeotropes with the methyl (meth) acrylate at a temperature below the boiling point of methyl (meth) acrylate, for example, cyclohexane, n Although -hexane etc. are mentioned, this invention is not limited only to this illustration. These azeotropic solvents may be used alone or in combination. Among these azeotropic solvents, cyclohexane is preferable from the viewpoint of shortening the reaction time of the transesterification reaction and efficiently recovering methyl (meth) acrylate.

  The amount of the azeotropic solvent is not particularly limited, but is usually about 5 to 200 parts by mass per 100 parts by mass of the total amount of methyl (meth) acrylate and alcohol corresponding to the target (meth) acrylic ester. That's fine.

  Other solvents may be used as long as the object of the present invention is not impaired. Examples of other solvents include n-pentane, n-hexane, isohexane, n-heptane, n-octane, 2,3-dimethylbutane, 2,5-dimethylhexane, and 2,2,4-trimethylpentane. Examples include aliphatic hydrocarbon compounds having 5 to 8 carbon atoms other than cyclohexane, but the present invention is not limited to such examples.

  From the viewpoint of efficiently transesterifying the methyl (meth) acrylate and the alcohol corresponding to the target (meth) acrylic ester, a reaction apparatus is obtained by azeotropically azeotropically azeotropically solvating the solvent and by-product methyl alcohol. It is preferred to remove by-product methyl alcohol vapor from the top of the distillation column attached to the column, preferably from the top of the column. From the viewpoint of efficiently removing the azeotropic solvent and by-produced methyl alcohol from the reactor, the top temperature of the distillation column is 5 ° C. higher than the azeotropic temperature from the azeotropic temperature of methyl alcohol and the azeotropic solvent. It is preferable to adjust the temperature so that it is within a temperature range, preferably up to 2 ° C. higher.

  When a methyl (meth) acrylate and an alcohol corresponding to the target (meth) acrylic ester are subjected to a transesterification reaction, a condensate is obtained by taking out the vapor from the upper part of the distillation column and condensing the vapor. As a result, methyl alcohol can be recovered. A part of this condensate is refluxed to the distillation column, and the remainder of the condensate is removed from the reactor, so that the temperature at the top of the distillation column can be shared with methyl alcohol without controlling the heating temperature of the reactor. It can be easily adjusted to the azeotropic temperature with the boiling solvent.

  By adding water to the condensate removed outside the reactor, the condensate can be efficiently separated into two layers, an upper layer and a lower layer. The amount of water per 100 parts by volume of the condensate to be added to the condensate is not particularly limited, but is usually preferably 10 parts by volume or more, more preferably 20 parts by volume or more from the viewpoint of efficiently separating the upper layer and the lower layer. From the viewpoint of reducing the amount of the lower layer to be generated, it is preferably 300 parts by volume or less, more preferably 200 parts by volume or less.

  In addition, the temperature of the condensate when water is added to the condensate is preferably 0 to 50 ° C., more preferably 0 to 40 ° C. from the viewpoint of efficiently separating the condensate into two layers of an upper layer and a lower layer. More preferably, it is 0-30 degreeC.

  When separating the condensate into two layers, an upper layer and a lower layer, for example, a separation device such as a decanter or a separatory funnel can be used.

  Of the two separated layers, the upper layer mainly contains an azeotropic solvent. The azeotropic solvent contained in this upper layer can be effectively used as a solvent for transesterification of methyl (meth) acrylate and the alcohol corresponding to the target (meth) acrylic ester.

  Therefore, in the present invention, from the viewpoint of effectively using the azeotropic solvent contained in the upper layer, the upper layer is preferably refluxed to the distillation column. When supplying the upper layer to the distillation column, the upper layer is preferably supplied to the middle part of the distillation column from the viewpoint of efficiently proceeding the transesterification reaction between methyl (meth) acrylate and alcohol. The middle part of the distillation tower means a stage near the center of the multistage distillation tower. For example, if the distillation column has 15 theoretical plates, 6 to 9 plates correspond to the middle column of the distillation column.

  Moreover, the fractionation ability of the distillation column can be increased by refluxing a part of the condensate to the distillation column. The amount of the condensate to be refluxed to the top of the distillation column is not particularly limited, but is about 20 to 95% by mass of the total amount of the condensate from the viewpoint of increasing the fractionation ability of the distillation column and increasing the reaction rate. Is preferable, and it is more preferable that it is about 50-90 mass%.

  When a part of the vapor condensate taken out from the upper part of the distillation tower is refluxed to the top of the distillation tower, water is added to the rest of the condensate in the same manner as described above to separate the upper layer and the lower layer into two layers. It is preferable. Since the azeotropic solvent is mainly contained in the upper layer of the two separated layers, the alcohol corresponding to the (meth) acrylic acid ester and the desired (meth) acrylic acid ester is formed in the same manner as described above. Can be effectively used as a reaction solvent in the transesterification reaction. At that time, the upper layer is preferably supplied to the middle part of the distillation column in the same manner as described above from the viewpoint of efficiently proceeding the transesterification reaction between methyl (meth) acrylate and alcohol.

  On the other hand, the lower layer mainly contains methyl alcohol and water. In addition to these components, azeotropic solvent and methyl (meth) acrylate are contained at a content of about 1 to 10% by mass, respectively. ing.

  If the lower layer is distilled, the azeotropic solvent and methyl (meth) acrylate contained in the lower layer can be azeotroped with methyl alcohol and removed from the lower layer as an azeotrope.

  It is preferable that water is added to the condensate removed outside the reaction apparatus to separate the upper layer and the lower layer into two layers, and the lower layer of the separated two layers is further placed in a distillation apparatus having a distillation column for distillation. When this lower layer was distilled, by adjusting the temperature at the top of the column to 64 ° C. or less, first, a vapor containing methyl (meth) acrylate, by-produced methyl alcohol and an azeotropic solvent was generated, and then the lower layer By adjusting the temperature to 64 to 66 ° C., it is possible to generate steam containing methyl alcohol as a main component by-produced by the transesterification reaction. Any generated steam can be taken out from the upper part of the distillation column.

  The lower layer can be distilled using a distillation apparatus having a distillation column. The distillation apparatus may be either a batch type or a flow type. Moreover, the pressure when distilling the lower layer may be either atmospheric pressure or reduced pressure. The number of theoretical columns of the distillation column used in the distillation is preferably 5 or more, more preferably 7 or more, and still more preferably from the viewpoint of efficiently azeotropically azeotropic solvent, methyl (meth) acrylate and methyl alcohol. Is 10 stages or more, and from the viewpoint of improving economy, it is preferably 100 stages or less, more preferably 70 stages or less, and even more preferably 50 stages or less. Moreover, the distillation temperature when distilling the lower layer is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 50 ° C. or higher. From the viewpoint of preventing polymerization of methyl (meth) acrylate, Preferably it is 120 degrees C or less, More preferably, it is 110 degrees C or less, More preferably, it is 105 degrees C or less.

  Since the vapor containing the methyl (meth) acrylate and by-produced methyl alcohol and the azeotropic solvent contains the azeotropic solvent, methyl (meth) acrylate and methyl alcohol, the vapor is condensed, The condensate obtained is preferably used as a raw material for transesterification of methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylate ester from the viewpoint of reducing the amount of waste. Moreover, after condensing the said vapor | steam and distilling the obtained condensate, it isolate | separates from methyl alcohol and water, Then, (meth) methyl acrylate and alcohol corresponding to the target (meth) acrylic ester It is preferable to use it as a raw material for the transesterification reaction from the viewpoint of effective utilization without containing by-produced methyl alcohol and water. The separated methyl alcohol and water can be used, for example, as water added to the condensate removed outside the reaction apparatus. Further, methyl alcohol and water can be easily separated by, for example, distillation purification. Since methyl alcohol separated from water contained in the residue does not contain impurities other than moisture, the methyl alcohol can be used as, for example, industrial raw materials, solvents, etc. Can be used.

  By the way, the reaction temperature at the time of carrying out the transesterification reaction of methyl (meth) acrylate and alcohol is preferably 70 ° C. or higher, more preferably 75 ° C. or higher, from the viewpoint of increasing the reaction rate. From the viewpoint of preventing polymerization of methyl acid and (meth) acrylic acid ester to be formed, it is preferably 140 ° C. or lower, more preferably 130 ° C. or lower, and further preferably 120 ° C. or lower.

  The atmosphere for performing the transesterification reaction of methyl (meth) acrylate and alcohol is an atmosphere containing oxygen from the viewpoint of preventing polymerization of raw material (meth) acrylate and (meth) acrylate produced. It is preferable that the oxygen concentration is 5% by volume to an atmospheric concentration gas from the viewpoint of improving safety. Moreover, the pressure of the atmosphere should just be atmospheric pressure normally, However, Pressurization or pressure reduction may be sufficient. For example, when the pressure of the atmosphere is reduced, the reflux temperature can be lowered, so that there is an advantage that side reactions can be suppressed.

  As the transesterification reaction between methyl (meth) acrylate and alcohol proceeds, the by-product rate of methyl alcohol decreases, and the transesterification reaction can be terminated when a predetermined reaction rate is reached. Note that methyl (meth) acrylate in the reaction apparatus disappears by azeotropy with the azeotropic solvent. Thus, when methyl (meth) acrylate in the reaction apparatus disappears, the top temperature of the distillation column finally reaches the boiling point of the azeotropic solvent. Therefore, the disappearance of methyl (meth) acrylate can be confirmed by the top temperature of the distillation column. For example, the transesterification of methyl (meth) acrylate and alcohol can be completed when the top temperature of the distillation column becomes about 5 ° C. higher than the azeotropic temperature of the azeotropic solvent and methyl alcohol. The end point of the transesterification reaction between methyl (meth) acrylate and alcohol can be confirmed, for example, by gas chromatography, liquid chromatography or the like.

  Since the reaction time for the transesterification reaction between methyl (meth) acrylate and alcohol varies depending on the amount of methyl (meth) acrylate and alcohol, reaction temperature, etc., it cannot be determined unconditionally, The time until the target reaction rate is reached is selected.

  The target (meth) acrylic acid ester can be obtained by carrying out a transesterification reaction between methyl (meth) acrylate and alcohol as described above.

  Next, after transesterifying the methyl (meth) acrylate with the alcohol corresponding to the target (meth) acrylic ester, the resulting reaction mixture is further heated and unreacted from the top of the distillation column. Remove the vapor containing methyl (meth) acrylate. In the present invention, after the transesterification, the reaction mixture in the reaction apparatus is further heated to take out the vapor containing unreacted methyl (meth) acrylate from the upper part of the distillation column. There are features. In this invention, since the said operation is taken, methyl (meth) acrylate used as a raw material can be efficiently collect | recovered from a reaction apparatus.

  After the transesterification reaction between methyl (meth) acrylate and alcohol, the temperature at which the reaction mixture in the reaction apparatus is heated varies depending on the type of azeotropic solvent used, so it should be determined in a general manner. Usually, the temperature of the transesterification reaction between methyl (meth) acrylate and alcohol, preferably 70 ° C. or higher, more preferably 75 ° C. or higher, is the raw material methyl (meth) acrylate and produced ( From the viewpoint of preventing polymerization of the (meth) acrylic acid ester, it is preferably 140 ° C. or lower, more preferably 130 ° C. or lower, and further preferably 120 ° C. or lower. Moreover, since the pressure at the time of heating the reaction mixture in the reaction apparatus can be atmospheric pressure, an apparatus for pressurization or depressurization is not required, but if necessary, the pressure is higher than atmospheric pressure. Or a low pressure.

  Vapor generated by heating the reaction mixture in the reactor can be recovered as a condensate by taking it out of the reactor from the top of the reactor, preferably from the top of the reactor, and cooling it.

  When the vapor generated by heating the reaction mixture in the reaction apparatus is taken out of the reaction apparatus, since the vapor contains azeotropic solvent vapor, the azeotropic solvent is removed from the reaction apparatus together with methyl (meth) acrylate. Since the amount of the azeotropic solvent removed and present in the reactor is reduced, in order to efficiently azeotrope methyl (meth) acrylate and the azeotropic solvent, if necessary, An azeotropic solvent may be added. The addition amount of the azeotropic solvent is not particularly limited as long as it is usually an amount that can azeotrope methyl (meth) acrylate and the azeotropic solvent.

  The end point of the operation for azeotroping methyl (meth) acrylate and the azeotropic solvent is not particularly limited, but it may be reduced as the amount of methyl (meth) acrylate remaining in the reactor decreases. Since the azeotropic temperature of the boiling matter approaches the boiling point of the azeotropic solvent, it is preferable to carry out until the boiling point of the azeotropic solvent is reached from the viewpoint of increasing the recovery efficiency of methyl (meth) acrylate.

  The recovered condensate as described above mainly contains recovered methyl (meth) acrylate, azeotropic solvent and methyl alcohol by-produced by transesterification, but the amount of by-produced methyl alcohol. However, since the amount of the condensed liquid is very small compared with the amount of the recovered methyl (meth) acrylate and the azeotropic solvent, the condensate is used as a raw material methyl (meth) acrylate when the transesterification reaction is newly performed. It can be used effectively.

  The target compound (meth) acrylic acid ester is present in the reaction mixture in the reaction apparatus, and can be recovered, for example, by removing the reaction mixture from the lower part of the reaction apparatus. In addition to the target compound (meth) acrylate, the reaction mixture contains the azeotropic solvent used in the transesterification reaction, a small amount of unreacted methyl (meth) acrylate and by-product methyl alcohol. Therefore, if necessary, the (meth) acrylic acid ester as the target compound can be recovered by removing these components. Removal of unreacted methyl (meth) acrylate, azeotropic solvent and by-produced methyl alcohol from the reaction mixture can be easily performed, for example, by distillation, extraction or the like.

  As described above, methyl (meth) acrylate can be efficiently recovered.

  The methyl (meth) acrylate is a malodorous substance and emits a strong odor when released into the atmosphere. Therefore, it is necessary not to discharge into the atmosphere or to reduce the amount released into the atmosphere as much as possible. .

  In contrast, according to the present invention, the methyl (meth) acrylate remaining in the reaction mixture after completion of the transesterification reaction is gently removed from the reaction mixture by azeotropy with an azeotropic solvent at atmospheric pressure. Since it can be easily removed, the amount of methyl (meth) acrylate discharged into the atmosphere can be minimized.

  Therefore, it can be said that the manufacturing method of the (meth) acrylic acid ester of this invention is an environmentally friendly manufacturing method in consideration of the environment.

  If necessary, the reactor is equipped with an alkali scrubber, for example, at the exhaust port to the atmosphere provided in the reactor to absorb methyl (meth) acrylate, and the atmosphere. The release of methyl (meth) acrylate may be suppressed.

  The (meth) acrylic acid ester obtained by the method for producing a (meth) acrylic acid ester of the present invention as described above is used as a raw material for, for example, a (meth) acrylic resin, a surfactant, an adhesive, and a paint. It is a useful compound.

  In addition, depending on the type and use of the target (meth) acrylic acid ester, it may be desired that the raw material (meth) acrylic acid ester does not mix with the (meth) acrylic acid ester. The method for producing a (meth) acrylic acid ester is also useful as a method for preventing the raw material (meth) acrylic acid ester from being mixed with the raw material (meth) acrylic acid methyl ester.

  Next, the present invention will be described in more detail based on examples. However, the present invention is not limited to such examples.

  In the following examples, the yield of the (meth) acrylic acid ester of the target compound is the ratio of the actual (meth) acrylic acid ester production amount to the theoretical (meth) acrylic acid ester production amount of the target compound. I asked for it.

  In addition, the amounts of raw material alcohol, (meth) acrylic acid ester, azeotropic solvent and methyl (meth) acrylate produced from the raw material alcohol and raw material alcohol in the reaction mixtures of the following examples are all gas chromatography (hereinafter referred to as GC). Using an analyzer (manufactured by Agilent, detector FID, column capillary DB-1: 30 m), the area percentage by GC was obtained.

Example 1
A 2 L four-necked flask equipped with a reflux apparatus at the top of the column and having a 20-stage Oldershaw distillation column (theoretical plate number: 15) having side tubes and an air introduction tube was used as the reaction apparatus. Into the reactor flask, 694 g (8.06 mol) of methyl acrylate, 552 g (6.20 mol) of N, N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltin oxide and 100 g of cyclohexane were charged. . The transesterification reaction was performed while air was blown into the flask at a flow rate of 20 mL / min from the air introduction tube. More specifically, the vapor taken out from the top of the distillation column installed in the reactor is condensed, a part of the resulting condensate is refluxed to the top of the column, and the remaining condensate is removed from the reactor. Removed. The top temperature of the distillation column was adjusted to 54 to 56 ° C., which is the azeotropic temperature of methyl alcohol and cyclohexane, by adjusting the amount of the condensate removed outside the reaction apparatus.

  700 g of the condensate removed from the top of the distillation column of the reactor and 200 g of water were mixed at a temperature of 20 ° C., and the resulting mixture was introduced into a decanter. This mixed solution was separated into two layers, an upper layer and a lower layer. Methyl alcohol contained in the condensate was extracted with water and contained in the lower layer, and cyclohexane contained in the condensate was contained in the upper layer of the extract.

  The amount of the lower layer is 410 g. In the lower layer, methyl alcohol 47.0% by mass (193 g), cyclohexane 0.5% by mass (2 g), methyl acrylate 3.6% by mass (15 g) and water 48. 9% by mass (200 g) was contained.

  On the other hand, the upper layer was effectively used by supplying it to the position of the 10th stage from the bottom of the distillation tower which is the middle stage of the distillation tower.

  The reaction is carried out while adding cyclohexane as appropriate in the flask so that the reaction temperature in the transesterification reaction between methyl acrylate and N, N-dimethylaminoethanol is 85 to 102 ° C., and the transesterification is carried out after 4 hours from the start of the reaction. Ended. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 160 g.

  After completion of the reaction, the reaction mixture obtained by the transesterification reaction is further heated, the reflux ratio is set to 10 to 15, the vapor is taken out from the top of the distillation column, and the vapor is condensed to obtain a condensate. It was collected. At this time, cyclohexane was added into the flask so that the temperature of the reaction mixture in the flask was maintained at 85 to 100 ° C. As the condensate was taken out from the top of the distillation tower, the top temperature of the distillation tower gradually increased, and distillation was continued until the top temperature of the distillation tower reached 80 ° C., which is the boiling point of cyclohexane.

  As a result, the content of methyl acrylate in the reaction mixture in the flask was 0.1% by mass or less. The amount of the condensate taken out and recovered from the tower top was 490 g, and this condensate contained 5 g of methanol, 145 g of methyl acrylate, and 340 g of cyclohexane. This condensate contained most of the methyl acrylate used in excess. This recovered condensate could be used in the transesterification reaction between methyl acrylate and N, N-dimethylaminoethanol. From this, it was confirmed that the loss of methyl acrylate can be prevented by using the condensate in the transesterification reaction between methyl acrylate and N, N-dimethylaminoethanol.

  As a result of preparing acrylic acid-N, N-dimethylaminoethyl as described above, the yield of acrylic acid-N, N-dimethylaminoethyl was 852 g (on the basis of N, N-dimethylaminoethanol). Yield of 96% by mass, yield based on the charged amount of methyl acrylate: 73.8% by mass, yield after reusing methyl acrylate recovered by azeotropy with cyclohexane after completion of the reaction Rate: 93.3% by mass).

  From the above results, according to Example 1, the condensate removed from the top of the distillation column of the reaction apparatus and water are mixed, the obtained mixed solution is separated, and the obtained upper layer is supplied to the distillation column. The reaction mixture obtained by the transesterification reaction can be further heated, and the condensate recovered from the top of the distillation column can be effectively utilized for a new transesterification reaction. It turns out that the target acrylic acid-N, N-dimethylaminoethyl can be prepared in high yield.

Example 2
A 1 L four-necked flask equipped with a reflux device at the top of the column and having a 10-stage Oldershaw distillation column (theoretical plate number: 7 plates) having side tubes and an air introduction tube was used as the distillation device. The lower layer obtained in Example 1 was charged into the flask of the reactor.

  Distillation was performed with the reflux ratio set to 10 to 15, and fraction A was recovered when the column top temperature was 64 ° C. or lower. As a result, the amount of fraction A recovered was 40 g. The composition of A was 62.1 mass% (25 g) of methyl alcohol, 32.5 mass% (13 g) of methyl acrylate, 5.3 mass% (2 g) of cyclohexane, and 0.1 mass% of water. This fraction A could be used in the transesterification reaction between methyl acrylate and N, N-dimethylaminoethanol.

  The distillation was continued and the reflux ratio was set to 5 to 10, and the fraction B was recovered when the column top temperature was 64 to 66 ° C. As a result, the amount of the fraction B recovered was The fraction B had a composition of 99.9% by mass of methyl alcohol and 0.1% by mass of water, and it was not confirmed that methyl acrylate was contained.

  Since the fraction B does not contain components other than methyl alcohol and a small amount of water, it was confirmed that it could be used effectively as an industrial raw material, a solvent, and the like. In addition, since methyl acrylate was not detected in fraction B, there was no loss of methyl acrylate, and it was confirmed that the yield of acrylic acid-N, N-dimethylaminoethyl was not adversely affected. .

  Further, the composition of 203 g of the residual liquid in the flask was 3% by mass of methyl alcohol and 97% by mass of water, and other components contained therein were not detected and mainly composed of water. The liquid could be used as water in mixing the condensate and water in Example 1.

  From the above results, according to Example 2, the condensate removed from the top of the distillation column of the reactor recovered in Example 1 was mixed with water, and the obtained mixture was separated. It can be seen that the lower layer can be effectively used.

Example 3
The same reactor used in Example 1 was used. Into the flask of the reactor, 517 g (6.00 mol) of methyl acrylate, 651 g (5.00 mol) of n-octyl alcohol, 1.76 g of phenothiazine, 0.72 g of tetramethyl titanium and 117 g of n-hexane were charged. . The transesterification reaction was performed while air was blown into the flask at a flow rate of 20 mL / min from the air introduction tube. More specifically, the vapor taken out from the top of the distillation column installed in the reactor is condensed, a part of the resulting condensate is refluxed to the top of the column, and the remaining condensate is removed from the reactor. Removed. The top temperature of the distillation column was adjusted to 48 to 50 ° C., which is the azeotropic temperature of methyl alcohol and n-hexane, by adjusting the amount of the condensate removed outside the reaction apparatus.

  549 g of the condensate removed from the top of the distillation column of the reactor and 100 g of water were mixed at a temperature of 20 ° C., and the resulting mixture was introduced into a decanter. This mixed solution was separated into two layers, an upper layer and a lower layer. Methyl alcohol contained in the condensate was extracted with water and contained in the lower layer, and n-hexane contained in the condensate was contained in the upper layer of the extract.

  The amount of the lower layer is 257 g. In the lower layer, methyl alcohol 56.4% by mass (145 g), n-hexane 1.6% by mass (4 g), methyl acrylate 3.1% by mass (8 g) and water. 38.9% by mass (100 g) was contained.

  On the other hand, the upper layer was effectively used by supplying it to the position of the 10th stage from the bottom of the distillation tower which is the middle stage of the distillation tower.

  The reaction temperature in the transesterification reaction between methyl acrylate and n-octyl alcohol was 90 to 110 ° C., and the transesterification reaction was completed after 8 hours from the start of the reaction. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 86 g.

  After completion of the reaction, the reaction mixture obtained by the transesterification reaction is further heated, the reflux ratio is set to 10 to 15, the vapor is taken out from the top of the distillation column, and the vapor is condensed to obtain a condensate. It was collected. At this time, n-hexane was added into the flask so that the temperature of the reaction mixture in the flask was maintained at 90 to 110 ° C. As the condensate was taken out from the top of the distillation tower, the top temperature of the distillation tower gradually increased, and distillation was continued until the top temperature of the distillation tower reached 68 ° C., the boiling point of n-hexane.

  As a result, the content of methyl acrylate in the reaction mixture in the flask was 0.2% by mass or less. The amount of the condensate taken out and recovered from the top of the tower was 392 g. In this condensate, 3.8% by mass of methanol (15 g), 18.6% by mass of methyl acrylate (73 g) and 77. 6% by mass (304 g) was contained. This condensate contained most of the methyl acrylate used in excess. This recovered condensate could be used in the transesterification reaction between methyl acrylate and n-octyl alcohol. From this, it was confirmed that the loss of methyl acrylate can be prevented by utilizing the condensate in the transesterification reaction between methyl acrylate and n-octyl alcohol.

  As a result of preparing n-octyl acrylate as described above, the yield of n-octyl acrylate was 912 g (yield based on n-octyl alcohol: 99.0% by mass, methyl acrylate (Yield when the amount of acrylate recovered is 82.5% by mass, methyl acrylate recovered by azeotropy with n-hexane after completion of the reaction is 96.0% by mass).

Example 4
A 2 L four-necked flask having a reflux device at the top of the column and having a 10-stage Oldershaw distillation column (theoretical plate number: 7 plates) having a side tube and an air introduction tube was used as the distillation device. The lower layer obtained in Example 3 was charged into the flask of the reactor.

  Distillation was performed with the reflux ratio set to 10 to 15, and fraction A was recovered when the column top temperature was 64 ° C. or lower. As a result, the amount of fraction A recovered was 32 g. The composition of A was 62.5 mass% (20 g) of methyl alcohol, 25.0 mass% (8 g) of methyl acrylate, 12.5 mass% (4 g) of n-hexane, and 0.1 mass% of water. This fraction A could be used in the transesterification reaction between methyl acrylate and n-octyl alcohol.

  The distillation was continued and the reflux ratio was set to 5 to 10, and the fraction B was recovered when the column top temperature was 64 to 66 ° C. As a result, the amount of the fraction B recovered was The composition of this fraction B was 99.9% by mass (122 g) of methyl alcohol and 0.1% by mass of water, and it was not confirmed that methyl acrylate was contained.

  Since the fraction B does not contain components other than methyl alcohol and a small amount of water, it was confirmed that it could be used effectively as an industrial raw material, a solvent, and the like. Moreover, since methyl acrylate was not detected in the fraction B, there was no loss of methyl acrylate, so it was confirmed that the yield of n-octyl acrylate was not adversely affected.

  The composition of the residual liquid 103 g in the flask is 3% by mass (3 g) of methyl alcohol and 97% by mass (100 g) of water, and other components are not detected and are mainly composed of water. Therefore, the residual liquid could be used as water when mixing the condensate and water in Example 3.

Example 5
The same reactor used in Example 1 was used. Into the flask of the reactor, 430 g (5.0 mol) of methyl acrylate, 675 g (7.5 mol) of 1,4-butanediol, 0.72 g of phenothiazine, 3.6 g of dioctyltin oxide and 100 g of cyclohexane were charged. . The transesterification reaction was performed while air was blown into the flask at a flow rate of 20 mL / min from the air introduction tube. More specifically, the vapor taken out from the top of the distillation column installed in the reactor is condensed, a part of the resulting condensate is refluxed to the top of the column, and the remaining condensate is removed from the reactor. Removed. The top temperature of the distillation column was adjusted to 54 to 56 ° C., which is the azeotropic temperature of methyl alcohol and cyclohexane, by adjusting the amount of the condensate removed outside the reaction apparatus.

  490 g of the condensate removed from the top of the distillation column of the reactor and 140 g of water were mixed at a temperature of 20 ° C., and the resulting mixture was introduced into a decanter. This mixed solution was separated into two layers, an upper layer and a lower layer. Methyl alcohol contained in the condensate was extracted with water and contained in the lower layer, and cyclohexane contained in the condensate was contained in the upper layer of the extract.

  The amount of the lower layer is 303 g. In the lower layer, methyl alcohol 48.7% by mass (148 g), cyclohexane 1.6% by mass (5 g), methyl acrylate 3.3% by mass (10 g) and water 46. 4 mass% (140 g) was contained.

  On the other hand, the upper layer was effectively used by supplying it to the position of the 10th stage from the bottom of the distillation tower which is the middle stage of the distillation tower.

  The reaction is carried out while appropriately adding cyclohexane to the flask so that the reaction temperature in the transesterification reaction between methyl acrylate and 1,4-butanediol is 85 to 100 ° C. finished. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 20 g.

  After completion of the reaction, the reaction mixture obtained by the transesterification reaction is further heated, the reflux ratio is set to 10 to 15, the vapor is taken out from the top of the distillation column, and the vapor is condensed to obtain a condensate. It was collected. At this time, cyclohexane was added into the flask so that the temperature of the reaction mixture in the flask was maintained at 85 to 100 ° C. As the condensate was taken out from the top of the distillation tower, the top temperature of the distillation tower gradually increased, and distillation was continued until the top temperature of the distillation tower reached 80 ° C., which is the boiling point of cyclohexane.

  As a result, the content of methyl acrylate in the reaction mixture in the flask was 0.2% by mass or less. The amount of the condensate taken out and recovered from the tower top was 75 g, and this condensate contained 5 g of methanol, 10 g of methyl acrylate and 60 g of cyclohexane. This condensate contained most of the methyl acrylate used in excess. This recovered condensate could be used in the transesterification reaction between methyl acrylate and 1,4-butanediol. From this, it was confirmed that the loss of methyl acrylate can be prevented by utilizing the condensate in the transesterification reaction between methyl acrylate and 1,4-butanediol.

  As a result of preparing 4-hydroxybutyl acrylate as described above, 496 g of 4-hydroxybutyl acrylate, 131 g of 1,4-butanediol diacrylate and 1,4-butane were obtained. Diol 305g was included. The 4-hydroxybutyl acrylate contained in this reaction mixture could be separated by extraction, distillation or adsorption using an adsorption tower.

Example 6
A 1 L four-necked flask equipped with a reflux device at the top of the column and having a 10-stage Oldershaw distillation column (theoretical plate number: 7 plates) having side tubes and an air introduction tube was used as the distillation device. The lower layer obtained in Example 5 was charged into the flask of the reactor.

  Distillation was performed with the reflux ratio set to 10 to 15, and fraction A was recovered when the column top temperature was 64 ° C. or lower. As a result, the amount of fraction A recovered was 42 g. The composition of A is methyl alcohol 64.3 mass% (27 g), methyl acrylate 23.8 mass% (10 g), cyclohexane 12.5 mass% (5 g) and water 0.1 mass% (0.04 g). there were. This fraction A could be used in the transesterification reaction between methyl acrylate and 1,4-butanediol.

  The distillation was continued, distillation was performed with the reflux ratio set to 5 to 10, and fraction B was recovered when the column top temperature was 64 to 65 ° C. As a result, the amount of fraction B recovered was The fraction B had a composition of 99.9% by mass of methyl alcohol and 0.1% by mass of water, and it was not confirmed that methyl acrylate was contained.

  Since the fraction B does not contain components other than methyl alcohol and a small amount of water, it was confirmed that it could be used effectively as an industrial raw material, a solvent, and the like. Further, since methyl acrylate was not detected in fraction B, it was confirmed that there was no loss of methyl acrylate, and therefore no adverse effect was exerted on the yield of 4-hydroxybutyl acrylate.

  Further, the composition of the residual liquid 142 g in the flask was 3% by mass of methyl alcohol and 97% by mass of water, and other components contained therein were not detected and mainly composed of water. The liquid could be used as water in mixing the condensate and water in Example 5.

Example 7
In the same reactor used in Example 1, methyl methacrylate 780.9 (7.80 mol), N, N-dimethylaminoethanol 372.4 g (6.00 mol) and phenothiazine 1.89 g were charged. Except that, transesterification was carried out in the same manner as in Example 1. After completion of the reaction, the amount of methyl methacrylate contained in the reaction mixture obtained by the transesterification reaction was 178 g.

  After adding cyclohexane to the flask and recovering 175 g of unreacted methyl methacrylate, the content of methyl methacrylate in the reaction mixture in the flask was examined. The content of methyl methacrylate was 0.1% by mass or less. Met.

  Next, the lower layer of the decanter was distilled in the same manner as in Example 2 to recover 5 g of a fraction A. The composition of this fraction A was 86.9% by mass of methyl alcohol, 13.0% by mass of cyclohexane and 0.1% by mass of water. This fraction A could be used for the transesterification reaction between methyl methacrylate and N, N-dimethylaminoethanol. Subsequently, the fraction B was recovered in the same manner as in Example 2 and the composition thereof was examined. The composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water.

Example 8
In the same reactor used in Example 1, methyl methacrylate 1041.2 (10.4 mol), ethylene glycol 248.3 g (4.00 mol), phenothiazine 1.59 and lithium hydroxide 0.96 g Was transesterified in the same manner as in Example 1 except that was charged. After completion of the reaction, the amount of methyl methacrylate contained in the reaction mixture obtained by the transesterification reaction was 235 g.

  After adding cyclohexane to the flask and recovering 233 g of unreacted methyl methacrylate, the content of methyl methacrylate in the reaction mixture in the flask was examined. The content of methyl methacrylate was 0.1% by mass or less. Met.

  Next, the lower layer of the decanter was distilled in the same manner as in Example 2 to recover 5 g of a fraction A. The composition of this fraction A was 86.9% by mass of methyl alcohol, 13.0% by mass of cyclohexane and 0.1% by mass of water. This fraction A could be used for the transesterification reaction between methyl methacrylate and ethylene glycol. Subsequently, the fraction B was recovered in the same manner as in Example 2 and the composition thereof was examined. The composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water.

Example 9
In Example 1, transesterification was performed in the same manner as in Example 1 except that 633.2 g (6.20 mol) of tetrahydrofurfuryl alcohol was used instead of N, N-dimethylaminoethanol. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 147 g.

  After adding cyclohexane into the flask and recovering 146 g of unreacted methyl acrylate, the content of methyl acrylate in the reaction mixture in the flask was examined. The content of methyl acrylate was 0.1% by mass or less. Met.

  Next, when the lower layer of the decanter was distilled in the same manner as in Example 2, the composition of the fraction A was 62.3% by mass of methyl alcohol, 32.1% by mass of methyl acrylate, 5.5% by mass of cyclohexane, and 0% of water. It was 1 mass%. This fraction A could be used for a transesterification reaction between methyl acrylate and tetrahydrofurfuryl alcohol. Subsequently, the fraction B was recovered in the same manner as in Example 2, and the composition thereof was examined. As a result, the composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water. Was not confirmed to be included.

Example 10
In Example 1, transesterification was performed in the same manner as in Example 1 except that 805.0 g (6.00 mol) of diethylene glycol monoethyl ether was used instead of N, N-dimethylaminoethanol. . After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 140 g.

  After cyclohexane was added into the flask and 138 g of unreacted methyl acrylate was recovered, the content of methyl acrylate in the reaction mixture in the flask was examined. The content of methyl acrylate was 0.1% by mass or less. Met.

  Next, when the lower layer of the decanter was distilled in the same manner as in Example 2, the composition of the fraction A was 62.3% by mass of methyl alcohol, 32.3% by mass of methyl acrylate, 5.3% by mass of cyclohexane, and water. It was 0.1 mass%. This fraction A could be used for a transesterification reaction between methyl acrylate and diethylene glycol monoethyl ether. Subsequently, the fraction B was recovered in the same manner as in Example 2, and the composition thereof was examined. As a result, the composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water. Was not confirmed to be included.

Example 11
Example 1 Example 1 except that methyl acrylate 894.8 (5.20 mol), 1,6-hexanediol 472.7 g (4.00 mol) and dioctyltin oxide 3.7 g were used. A transesterification reaction was carried out in the same manner as described above. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 189 g.

  After cyclohexane was added to the flask and 188 g of unreacted methyl acrylate was recovered, the content of methyl acrylate in the reaction mixture in the flask was examined. The content of methyl acrylate was 0.1% by mass. It was the following.

  Next, when the lower layer of the decanter was distilled in the same manner as in Example 2, the composition of the fraction A was 62.1% by mass of methyl alcohol, 32.4% by mass of methyl acrylate, 5.4% by mass of cyclohexane, and water. It was 0.1 mass%. This fraction A could be used for a transesterification reaction between methyl acrylate and 1,6-hexanediol. Subsequently, the fraction B was recovered in the same manner as in Example 2, and the composition thereof was examined. As a result, the composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water. Was not confirmed to be included.

Example 12
In the same manner as in Example 1, except that 1006.7 g (11.7 mol) of methyl acrylate, 402.5 g (3.00 mol) of trimethylolpropane and 8.4 g of dioctyltin oxide were used. The transesterification reaction was performed. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 216 g.

  After adding cyclohexane to the flask and recovering 214 g of unreacted methyl acrylate, the content of methyl acrylate in the reaction mixture in the flask was examined. The content of methyl acrylate was 0.1% by mass. It was the following.

  Next, when the lower layer of the decanter was distilled in the same manner as in Example 2, the composition of the fraction A was 62.1% by mass of methyl alcohol, 32.3% by mass of methyl acrylate, 5.5% by mass of cyclohexane, and water. It was 0.1 mass%. This fraction A could be used for a transesterification reaction between methyl acrylate and trimethylolpropane. Subsequently, the fraction B was recovered in the same manner as in Example 2, and the composition thereof was examined. As a result, the composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water. Was not confirmed to be included.

Example 13
In Example 1, methyl acrylate 559.3 (6.5 mol), 2-ethyl-2-methyl-1,3-dioxolane-4-methanol 1041.5 g (5.00 mol) and dioctyltin oxide. A transesterification reaction was carried out in the same manner as in Example 1 except that 7 g was used. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 117 g.

  After adding cyclohexane into the flask and recovering 116 g of unreacted methyl acrylate, the content of methyl acrylate in the reaction mixture in the flask was examined. The content of methyl acrylate was 0.1% by mass. It was the following.

  Next, when the lower layer of the decanter was distilled in the same manner as in Example 2, the composition of the fraction A was 62.5% by mass of methyl alcohol, 32.1% by mass of methyl acrylate, 5.3% by mass of cyclohexane, and water. It was 0.1 mass%. This fraction A could be used for the transesterification reaction between methyl acrylate and 2-ethyl-2-methyl-1,3-dioxolane-4-methanol. Subsequently, the fraction B was recovered in the same manner as in Example 2, and the composition thereof was examined. As a result, the composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water. Was not confirmed to be included.

Example 14
In Example 1, methyl acrylate 615.2 (7.15 mol), 3-ethyl-3-oxetanylmethyl alcohol 892.1 g (5.50 mol) and dioctyltin oxide 5. A transesterification reaction was carried out in the same manner as in Example 1 except that lg was used. After completion of the reaction, the amount of methyl acrylate contained in the reaction mixture obtained by the transesterification reaction was 123 g.

  After adding cyclohexane to the flask and recovering 122 g of unreacted methyl acrylate, the content of methyl acrylate in the reaction mixture in the flask was examined. The content of methyl acrylate was 0.1% by mass. It was the following.

  Next, when the lower layer of the decanter was distilled in the same manner as in Example 2, the fraction A had a composition of 62.3% by mass of methyl alcohol, 32.1% by mass of methyl acrylate, 5.5% by mass of cyclohexane, and water. It was 0.1 mass%. This fraction A could be used for the transesterification reaction between methyl acrylate and 3-ethyl-3-oxetanylmethyl alcohol. Subsequently, the fraction B was recovered in the same manner as in Example 2, and the composition thereof was examined. As a result, the composition of the fraction B was 99.9% by mass of methyl alcohol and 0.1% by mass of water. Was not confirmed to be included.

Comparative Example 1
The same reactor used in Example 1 was used. Into the reactor flask, 694 g (8.06 mol) of methyl acrylate, 552 g (6.20 mol) of N, N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltin oxide and 100 g of isohexane were charged. .

  Next, a transesterification reaction was performed at a reaction temperature of 76 to 93 ° C. while air was blown into the flask at a flow rate of 20 mL / min. More specifically, the vapor taken out from the top of the distillation column installed in the reactor is condensed, a part of the resulting condensate is refluxed to the top of the column, and the remaining condensate is removed outside the reactor. did. The top temperature of the distillation column was adjusted to 45 to 46 ° C., which is the azeotropic temperature of methyl alcohol and isohexane, by adjusting the amount of the condensate removed outside the reaction apparatus.

  950 g of the condensate removed outside the reaction apparatus and 200 g of water were mixed at a temperature of 20 ° C., and the resulting mixture was introduced into a decanter and separated into two layers. Of the two layers, the lower layer contained methyl alcohol contained in the condensate. On the other hand, isohexane was contained in the upper layer, and the upper layer was supplied to the 10th stage from the bottom corresponding to the middle stage of the distillation column.

  The transesterification reaction between methyl acrylate and N, N-dimethylaminoethanol was completed by reacting methyl acrylate with N, N-dimethylaminoethanol for 13 hours.

  When the steal exchange reaction was completed, the amount of methyl acrylate remaining in the reaction apparatus was 160 g.

  Next, while adding isohexane to the flask so that the temperature of the reaction mixture in the flask was 80 to 90 ° C., the reflux ratio was set to 10 to 15, and the condensate was taken out from the top of the column. When the condensate was removed from the top of the tower, the top temperature quickly reached 62 ° C., which is the boiling point of isohexane. The amount of condensate taken out from the top of the column was 300 g.

  As a result, the residual amount of methyl acrylate in the reactor was 10.8% by mass. Further, 300 g of the condensate taken out from the top of the tower contained 5 g of methanol, 5 g of methyl acrylate, and 290 g of isohexane. From this, it was confirmed that the condensate contained almost no methyl acrylate used as a raw material, and most of the methyl acrylate remained in the reactor.

  From the above results, the amount of methyl acrylate remaining in the reaction apparatus at the end of the reaction was 160 g. Further, in the operation after completion of the reaction, methyl acrylate was not azeotroped with isohexane, and only 5 g was recovered.

Comparative Example 2
A 2 L four-necked flask equipped with a reflux apparatus at the top of the column and having a 20-stage Oldershaw distillation column (theoretical plate number: 15) having side tubes and an air introduction tube was used as the reaction apparatus. Into the reactor flask, 694 g (8.06 mol) of methyl acrylate, 552 g (6.20 mol) of N, N-dimethylaminoethanol, 1.76 g of phenothiazine, 22.1 g of dibutyltin oxide and 100 g of cyclohexane were charged. . The transesterification reaction was performed while air was blown into the flask at a flow rate of 20 mL / min from the air introduction tube.

Specifically, the vapor taken out from the top of the distillation tower installed in the reaction apparatus is condensed, a part of the resulting condensate is refluxed to the top of the tower, and the remaining condensate is removed from the reaction apparatus. Removed. The top temperature of the distillation column was adjusted to 54 to 56 ° C., which is the azeotropic temperature of methyl alcohol and cyclohexane, by adjusting the amount of the condensate removed outside the reaction apparatus.

  700 g of the condensate removed from the top of the distillation column of the reactor and 200 g of water were mixed at a temperature of 20 ° C., and the resulting mixture was introduced into a decanter. This mixed solution was separated into two layers, an upper layer and a lower layer. Methyl alcohol contained in the condensate was extracted with water and contained in the lower layer, and cyclohexane contained in the condensate was contained in the upper layer of the extract. The amount of the lower layer is 410 g. In the lower layer, methyl alcohol 47.0% by mass (193 g), cyclohexane 0.5% by mass (2 g), methyl acrylate 3.6% by mass (15 g) and water 48.9 Mass% (200 g) was included.

  The reaction is carried out while adding cyclohexane as appropriate in the flask so that the reaction temperature in the transesterification reaction between methyl acrylate and N, N-dimethylaminoethanol is 85 to 102 ° C., and the transesterification is carried out after 4 hours from the start of the reaction. Ended.

  As a result, the yield of acrylic acid-N, N-dimethylaminoethyl was 96.0% by mass, and the yield based on methyl acrylate was 73.8% by mass. The composition of the aqueous layer from which methanol was extracted from the condensate was 48.0% by mass of methanol, 0.1% by mass of n-hexane and 3.6% by mass of methyl acrylate, but remained in the reactor. The residual amount of methyl acrylate was 160 g.

  Therefore, in the method of Comparative Example 2, it can be seen that a large amount of methyl acrylate remains in the reactor.

  From the above results, according to each example of the present invention, the (meth) acrylic acid ester remaining after the transesterification reaction of methyl (meth) acrylate and alcohol can be efficiently recovered, In addition, the recovered methyl (meth) acrylate can be reused when transesterifying the methyl (meth) acrylate with alcohol.

Claims (7)

The target (meth) acrylate ester is obtained by transesterifying the methyl (meth) acrylate and the alcohol corresponding to the target (meth) acrylate ester using methyl (meth) acrylate as a raw material. Using a reaction apparatus having a distillation column as a reaction apparatus, and transesterification of methyl (meth) acrylate and alcohol corresponding to the desired (meth) acrylate ester in the reaction apparatus When using, an azeotropic solvent that azeotropes with the methyl alcohol at a temperature below the boiling point of methyl alcohol and azeotropes with the methyl (meth) acrylate at a temperature below the boiling point of methyl (meth) acrylate is used. Esterifying methyl (meth) acrylate with alcohol corresponding to the desired (meth) acrylic ester After reacting, the reaction mixture in the reactor was further heated at a temperature of 70 to 140 ° C., unreacted from the top of the distillation column (meth) characterized by taking out the vapor containing methyl acrylate (meth ) A method for producing acrylic ester.   The method for producing a (meth) acrylic acid ester according to claim 1, wherein the azeotropic solvent is at least one selected from the group consisting of cyclohexane and n-hexane.   During the transesterification reaction between methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylic acid ester, the vapor is taken out from the upper part of the distillation column, the taken-out vapor is condensed, and the resulting condensate The temperature of the upper part of the distillation column is adjusted to the azeotropic temperature of the alcohol and the azeotropic solvent by removing a part of the water to the distillation column and removing the remaining condensate from the reaction apparatus. The manufacturing method of the (meth) acrylic acid ester of description.   4. The (meth) acrylic acid ester according to claim 3, wherein water is added to the condensate removed outside the reaction apparatus, the upper layer and the lower layer are separated, and the upper layer of the separated two layers is refluxed to the distillation column. Production method.   Water is added to the condensate removed outside the reactor and separated into two layers, an upper layer and a lower layer. Of the separated two layers, the lower layer is further placed in a distillation apparatus having a distillation tower and distilled, and (meth) acrylic is distilled. 5. The vapor containing methyl acid by-produced methyl alcohol and an azeotropic solvent, and the vapor containing methyl alcohol by-produced by transesterification as a main component are respectively taken out from the upper part of the distillation column. A method for producing a (meth) acrylic acid ester.   (Meth) according to claim 5, wherein a vapor containing methyl (meth) acrylate, by-produced methyl alcohol and an azeotropic solvent is used as a raw material in a transesterification reaction between methyl (meth) acrylate and the alcohol. A method for producing an acrylic ester.   After the transesterification reaction between methyl (meth) acrylate and the alcohol corresponding to the desired (meth) acrylic ester, unreacted (meth) acrylic removed from the top of the distillation column by further heating the reaction mixture The vapor containing methyl acid is condensed, and the resulting condensate is used as a raw material in a transesterification reaction between methyl (meth) acrylate and the alcohol. A method for producing an acrylic ester.