Method for preparing sorbitol ketal acrylate by transesterification

Abstract

A method for preparing sorbitol ketal acrylate by transesterifying ethyl acrylate with sorbitol ketal, comprising: (i) reacting ethyl acrylate with sorbitol ketal in the presence of a catalyst containing titanium (IV) or zirconium (IV) and a stabilizer in the presence of ethyl acrylate as an azeotropic agent that forms an azeotrope with ethanol; and (ii) continuously distilling off and condensing an azeotrope containing ethyl acrylate and ethanol using a distillation column operated under reflux conditions, wherein steps (i) and (ii) are carried out simultaneously until the sorbitol ketal conversion rate reaches 95% or more, and step (ii) is carried out by diluting the condensed azeotrope with additional ethyl acrylate and using this mixture as reflux to the distillation column.

Description

Technical Field

[0001] The present invention relates to a method for preparing sorbitol ketal acrylate by transesterification of sorbitol ketal and ethyl acrylate.

Background Art

[0002] Sorbitol ketal acrylate ((2,2-dimethyl-1,3-dioxolan-4-yl) methyl acrylate, IPGA) is particularly useful as a reactive diluent in curable compositions, such as printing inks, preferably inkjet printing inks. Sorbitol ketal acrylate is an excellent monofunctional monomer acrylate and has an excellent performance profile not found in any commercially available monofunctional monomer acrylate in UV inkjet. This combines a very low viscosity both as a pure substance and in the formulation of UV inkjet inks, a very high curing rate, and very good adhesion to various substrates such as plastic films.

[0003] International Publication No. 2018 / 146258 describes the preparation of methyl (2,2-dimethyl-1,3-dioxolan-4-yl) acrylate (sorbitol ketal acrylate, IPGA)

Chemical Formula

[0004] Chinese Patent No. 106008447 also discloses a method for preparing acrylate of 2,2-dimethyl-1,3-dioxolane methanol (solketal) by transesterification with methyl acrylate in the presence of an organotitanium or organotin catalyst, such as tetrabutyl titanate, butyl titanate, tetraisopropyl titanate, dibutyltin dilaurate, dibutyltin dichloride, tributyltin acetate, dibutyltin oxide, and tributyltin chloride.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The object of the present invention is to provide a method for preparing sorcetal acrylate by transesterification of ethyl acrylate with sorcetal ((2,2-dimethyl-1,3-dioxolan-4-yl) methanol), in which the reaction time or batch time is minimized.

Means for Solving the Problems

[0007] This object is a method for preparing sorcetal acrylate by transesterifying ethyl acrylate with sorcetal, comprising: (i) reacting ethyl acrylate with sorcetal in the presence of a catalyst containing titanium (IV) or zirconium (IV) and a stabilizer in the presence of ethyl acrylate as an azeotropic agent that forms an azeotrope with ethanol; (ii) continuously distilling off and condensing an azeotrope containing ethyl acrylate and ethanol using a distillation column operated under reflux conditions; and wherein steps (i) and (ii) are carried out simultaneously until the sorcetal conversion rate reaches 95% or more; step (ii) is characterized in that the condensed azeotrope is diluted with additional ethyl acrylate and this mixture is used as reflux to the distillation column. This is achieved by the method.

[0008] Surprisingly, by diluting the condensed azeotrope containing ethyl acrylate and ethanol with essentially pure ethyl acrylate, starting the boiling of the reaction mixture, and using this mixture as reflux to the column as soon as the distillate containing ethyl acrylate and ethanol is condensed and withdrawn at the top of the column, it has been found that the reaction time can be significantly shortened. In the context of the present invention, essentially pure means that ethyl acrylate has a purity of at least 98% by weight.

[0009] Essentially pure ethyl acrylate may contain up to 2% by weight of ethanol.

[0010] In a preferred embodiment, the step of diluting the azeotrope with ethyl acrylate is carried out by pre-filling an ethyl acrylate distillate collection vessel and mixing the azeotrope withdrawn from the top of the distillation column with ethyl acrylate in this vessel. By this method, the azeotrope is continuously diluted with ethyl acrylate and then returned to the top of the distillation column as reflux.

[0011] Generally, the ethanol content of the reflux during the execution of steps (i) and (ii) is in the range of 10 wt% to 30 wt%.

[0012] Generally, the reflux:distillate reflux ratio in the distillation column is 10:1 to 2:1, preferably 10:2 to 3:1, more preferably 4:1 to 2:1.

[0013] The reaction between ethyl acrylate and sorbetal is carried out in the presence of a catalyst containing titanium(IV) or zirconium(IV). Suitable catalysts containing titanium(IV) or zirconium(IV) are Ti(IV) and Zr(IV) tetraalkoxides of linear or branched C1-C6 alcohols, preferably tetraethoxide, tetraisopropoxide, tetrabutoxide and metalates of the reaction alcohol used or mixtures thereof. Metalates substituted with various alcohols or acetylacetone are also possible.

[0014] The reaction of ethyl acrylate with sorbitol ketal is further carried out in the presence of one or more stabilizers (polymerization inhibitors). Examples of suitable stabilizers are N-oxides (nitroxyls or N-oxyl radicals, i.e., compounds having at least one N—O group), such as 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine N-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidine N-oxyl, 2,2,6,6-tetramethylpiperidine N-oxyl, bis(1-oxyl-2,2,6,6-tetramethylpiperidin-4-yl) sebacate, 4,4′,4″-tris(2,2,6,6-tetramethylpiperidine N-oxyl) phosphite or 3-oxo-2,2,5,5-tetramethylpyrrolidine N-oxyl; monohydric or polyhydric phenols which may have one or more alkyl groups, such as alkylphenols, such as o-, m- or p-cresol (methylphenol), 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 2-tert-butyl-4-methylphenol, 2,6-tert-butyl-4-methylphenol, 4-tert-butyl-2,6-dimethylphenol or 6-tert-butyl-2,4-dimethylphenol; quinones, such as hydroquinone, hydroquinone monomethyl ether, 2-methylhydroquinone or 2,5-di-tert-butylhydroquinone; hydroxyphenols, such as catechol (1,2-dihydroxybenzene) or benzoquinone; aminophenols, such as p-aminophenol; nitrosophenols, such as p-nitrosophenol; alkoxyphenols, such as 2-methoxyphenol (guaiacol, catechol monomethyl ether), 2-ethoxyphenol, 2-iso-propoxyphenol, 4-methoxyphenol (hydroquinone monomethyl ether), mono- or di-tert-butyl-4-methoxyphenol;Tocopherols, such as α-tocopherol and 2,3-dihydro-2,2-dimethyl-7-hydroxybenzofuran (2,2-dimethyl-7-hydroxycoumaran); aromatic amines, such as N,N-diphenylamine or N-nitrosodiphenylamine; phenylenediamines, such as N,N'-dialkyl-p-phenylenediamine (the alkyl groups may be the same or different, each independently may consist of 1 to 4 carbon atoms, and may be linear or branched), such as N,N'-dimethyl-p-phenylenediamine or N,N'-diethyl-p-phenylenediamine; hydroxylamines, such as N,N-diethylhydroxylamine; imines, such as methyl ethyl imine or methylene violet; sulfonamides, such as N-methyl-4-toluenesulfonamide or N-tert-butyl-4-toluenesulfonamide; oximes such as aldoxime, ketoxime or amidoxime, such as diethyl ketoxime, methyl ethyl ketoxime or salicylaldoxime; phosphorus compounds, such as triphenylphosphine, triphenyl phosphite, triethyl phosphite, hypophosphorous acid or an alkyl ester of phosphorous acid; sulfur compounds, such as diphenyl sulfide or phenothiazine, or a mixture thereof.;

[0015] Preferred are hydroquinone, hydroquinone monomethyl ether, phenothiazine, 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine N-oxyl, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-tert-butyl-4-methylphenol, 6-tert-butyl-2,4-dimethylphenol, 2,6-di-tert-butyl-4-methylphenol and 2-methyl-4-tert-butylphenol and phenothiazine.

[0016] Particularly preferred are hydroquinone monomethyl ether (MeHQ), phenothiazine (PTZ), and 4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide (HO-TEMPO).

[0017] Advantageously, oxygen may further be used as a polymerization inhibitor.

[0018] For further stabilization, oxygen gas, preferably air or a mixture of air and nitrogen (lean air), may be present.

[0019] The transesterification reactions (steps (i) and (ii)) are generally carried out at a temperature of 60 °C to 120 °C, preferably 70 °C to 110 °C. During this process, the azeotrope of ethyl acrylate and ethanol is continuously distilled off.

[0020] Generally, ethyl acrylate is used in a stoichiometric excess. Preferably, the excess amount of ethyl acrylate per sor ketal to be esterified is up to 300% by weight, more preferably up to 200% by weight, particularly 110 - 150% by weight.

[0021] The catalyst is used at a concentration of 0.1 - 10 mol%, preferably 0.1 - 5 mol%, based on the amount of sor ketal used.

[0022] The transesterification in steps (i) and (ii) can be carried out at atmospheric pressure, but can also be carried out under high pressure or reduced pressure. Generally, it is carried out at 100 - 1000 mbar, preferably 300 - 800 mbar (atmospheric pressure = 1000 mbar). The reaction time is generally 5 - 120 hours, preferably 12 - 48 hours.

[0023] Most preferably, steps (i) and (ii) are carried out at a pressure of 400 - 600 mbar(a) and a temperature of 80 - 105 °C.

[0024] The reaction can be carried out in any reactor suitable for this type of reaction. Such reactors are known to those skilled in the art. The reaction is preferably carried out in a stirred tank reactor.

[0025] The batch can be mixed using any desired device, such as a stirrer. Mixing can also be carried out by supplying a gas, preferably an oxygen-containing gas.

[0026] Ethyl acrylate may be used as an azeotropic agent and then replenished into the reactor. For this purpose, the azeotropic mixture of distilled ethyl acrylate and ethanol is stirred with water in a mixing vessel and then transferred to a phase separator, where ethanol dissolves in water and the organic phase separates as the upper layer. The organic phase can be returned to the reaction mixture. Alternatively, it is also possible to add fresh ethyl acrylate, to post-treat the ethyl acrylate / ethanol mixture in a separate step, or to omit all or part of the replenishment of ethyl acrylate.

[0027] In one embodiment, ethanol is removed by washing with water from the azeotrope of ethyl acrylate and ethanol distilled off in step (ii). Ethyl acrylate may be recycled to the reaction vessel.

[0028] Steps (i) and (ii) are carried out until the sorbitol ketal used is converted to the acrylic acid ester to at least about 95%, preferably at least about 97%.

[0029] Preferably, the method of the present invention comprises step (iii): (iii) Evaporating unreacted ethyl acrylate from the product mixture under evaporation conditions when the sorbitol ketal conversion rate reaches 95% or more further comprises.

[0030] In particular, step (iii) is carried out when the sorbitol ketal conversion rate reaches 97% or more.

[0031] Preferably, step (iii) is carried out at a pressure of 10 to 500 mbar and a temperature of 60 to 100 °C.

[0032] Preferably, the method of the present invention comprises an additional step (iv): (iv) Stripping the remaining ethyl acrylate from the product mixture using a gas stream is included.

[0033] The gas stream used in step (iv) may be an inert gas stream such as a nitrogen gas stream or an oxygen-containing gas stream such as an air stream.

[0034] Preferably, step (iv) is carried out until the ethyl acrylate concentration in the product mixture reaches 200 ppm or less.

[0035] The product mixture containing sor ketal acrylate and a catalyst can be further post-treated by subsequent steps (v) to (vii): (v) Adding water to the product mixture containing sor ketal acrylate and a catalyst (vi) Distilling off water from the product mixture (vii) Removing the hydrolysis product of the catalyst containing titanium (IV) or zirconium (IV) can be further post-treated.

[0036] Step (vii) can also be carried out before step (vi). Step (v) can also be carried out before step (iii). Then, step (vi) can be carried out together with step (iii). Alternatively, steps (v) and (vi) can also be carried out before step (iv).

[0037] This distillation (vi) is generally carried out at a temperature of 40 °C to 100 °C, preferably 60 °C to 100 °C, and a variable pressure of 2 to 700 mbar. The distillation removal can be carried out, for example, in a stirred tank equipped with jacket heating and / or internal heating coils under reduced pressure.

[0038] The poorly soluble hydrolysis products are removed in step (vii), for example, by filtration or centrifugation.

[0039] Filtration can be carried out, for example, using a pressure filter. In the terminology of process engineering, for filtration in the process of the present invention, any filtration method and apparatus known per se, for example, those described in Ullmann’s Encyclopedia of Industrial Chemistry, 7th ed., 2013 Electronic Release, chapter: Filtration, 1. Fundamentals and Filtration 2. Equipment, can be used. For example, these can be cartridge filters, filter presses, pressure plate filters, bag filters or drum filters. It is preferred to use a cartridge filter or a pressure plate filter. Filtration can be carried out with or without the use of a filter aid. Suitable filter aids are diatomaceous earth, perlite and cellulose-based filter aids.

[0040] Suitable centrifuges and separators are known to those skilled in the art. In the terminology of process engineering, for centrifugation in the process of the present invention, any centrifugation method and apparatus known per se, for example, those described in Ullmann’s Encyclopedia of Industrial Chemistry, 7th ed., 2013 Electronic Release, chapter: Centrifuges, Filtering and Centrifuges, Sedimenting, can be used.

[0041] The present invention will be described in more detail by the following examples.

Mode for Carrying Out the Invention

[0042] Examples Simulation Study All process simulation studies were carried out using CHEMADIS, a discontinuous process flow sheet simulation tool of BASF SE. The simulation tool predicts the transient behavior over time based on its own measurements using a publicly available physical property database and established thermodynamic models. The reaction rate model was derived from laboratory experiments and incorporated into the process simulation.

[0043] Example 1 A 14 m three-stage cross-arm agitator equipped with a column having 10 theoretical plates (Koch-Glitsch IMTP 25 random packing), a condenser, a reflux pump, a reflux splitter, a distillate drum, a vacuum system and an air inlet. 3 To a half-coil jacket reactor, sor ketal (3322 kg), ethyl acrylate (2200 kg stabilized with 1250 ppm MEHQ and 4386 kg stabilized with 15 ppm MEHQ) and 464 kg of an internal recycle stream (50 wt% ethyl acrylate, the balance ethanol) were added. Titanium tetraisopropoxide (88 kg) was added, air introduction was started, and the mixture was heated to a sample temperature of 85 °C at 600 mbar vacuum using 1.5 barg steam. The distillate drum was pre-filled with 2500 kg of ethyl acrylate stabilized with 15 ppm MEHQ, and when the mixture began to boil (t = 0 h), the reflux ratio was adjusted to 4 (reflux: distillate). When the sample temperature reached 97 °C, the vacuum was continuously lowered to keep the sample temperature constant at 97 °C. When the sor ketal conversion in the sample exceeded 98% (t = 30 h), the reflux was set to 0 and the remaining ethyl acrylate was evaporated. When the vacuum reached less than 40 mbar (t = 32 h), evaporation was stopped by stopping the steam supply, and an air flow of 8.5 Nm was continuously applied. 3It was increased until the time, and residual ethyl acrylate was stripped from the sample. Stripping was terminated when the sample concentration showed less than 100 ppm of ethyl acrylate concentration, and the reactor was cooled with cooling water in the jacket. The crude product was obtained with a yield of 4416 kg and a purity of 97%. The unreacted excess ethyl acrylate pre-filled in the distillate drum can be used in other processes where impurities such as isopropanol are also removed.

[0044] Example 2 A 14 m three-stage cross-arm agitator equipped with a column (Koch-Glitsch IMTP 25 random packing) with 10 theoretical plates, a condenser, a reflux pump, a reflux splitter, a distillate drum, a vacuum system and an air introduction section 3 To a half-coil jacket reactor, sor ketal (3322 kg), ethyl acrylate (2200 kg stabilized with 1250 ppm MEHQ and 4386 kg stabilized with 15 ppm MEHQ), and 464 kg of internal recycle stream (50 wt% ethyl acrylate, the rest ethanol) were added. Titanium tetraisopropoxide (88 kg) was added, air introduction was started, and the mixture was heated to a sample temperature of 85 °C at 600 mbar vacuum using 1.5 barg steam. The distillate drum was not pre-filled, and when the mixture started to boil (t = 0 h), the reflux ratio was adjusted to 4 (reflux: distillate). When the sample temperature reached 97 °C, the vacuum was continuously lowered to keep the sample temperature constant at 97 °C. When the sor ketal conversion rate in the sample exceeded 98% (t = 35 h), the reflux was set to 0 and the remaining ethyl acrylate was evaporated. When the vacuum reached less than 40 mbar (t = 37 h), evaporation was stopped by stopping the steam supply, and the air flow was continuously increased to 8.5 Nm 3 It was increased until the time, and residual ethyl acrylate was stripped from the sample. Stripping was terminated when the sample concentration showed less than 100 ppm of ethyl acrylate concentration, and the reactor was cooled with cooling water in the jacket. The same amount of crude product was obtained with a purity of 97% at a time 5 hours more than in the preferred Example 1.

[0045] Example 3 A 14 m three-stage cross-arm agitator equipped with a column with 10 theoretical plates (Koch-Glitsch IMTP 25 random packing), a condenser, a reflux pump, a reflux splitter, a distillate drum, a vacuum system, and an air inlet 3 To a half-coil jacket reactor, sor ketal (3322 kg), ethyl acrylate (2200 kg stabilized with 1250 ppm MEHQ and 4386 kg stabilized with 15 ppm MEHQ), and 464 kg of internal recycle stream (50 wt% ethyl acrylate, the balance ethanol) were added. Titanium tetraisopropoxide (88 kg) was added, air introduction was started, and the mixture was heated to a sample temperature of 85 °C at 600 mbar vacuum using 1.5 barg steam. The distillate drum was not pre-filled, and when the mixture began to boil (t = 0 h), the reflux ratio was adjusted to 4 (reflux: distillate). When the sample temperature reached 97 °C, the vacuum was continuously lowered to keep the sample temperature constant at 97 °C. When the sor ketal conversion in the sample exceeded 98% (t = 35 h), the reflux ratio was kept constant at 4, and the remaining ethyl acrylate was removed in distillation mode. When the vacuum reached less than 40 mbar (t = 48 h), the reflux was set to 0, the steam supply was stopped, and the air flow was continuously increased to 8.5 Nm 3 / h to strip the remaining ethyl acrylate from the sample. Stripping was terminated when the sample concentration showed less than 100 ppm ethyl acrylate concentration, and the reactor was cooled with cooling water in the jacket. The crude product was obtained with a yield of 4520 kg and a purity of 98% in a time 11 hours longer than in Example 2. Although the production rate in distillation mode is about 100 kg more per batch, the batch time is significantly longer, so the annual production rate is significantly lower.

[0046] Example 4 A 4L double-jacket reactor equipped with a column (Montz A3-750 packing), a cooler, a reflux splitter, a three-stage cross-arm agitator, and a dilute air introduction section was charged with ethyl acrylate (2000 g), ethyl acrylate-ethanol azeotrope from a previous experiment (190 g), MeHQ (1.27 g), and solketal (1000 g). The mixture was heated to a sample temperature of 85 °C at 600 mbar while introducing dilute air, and titanium tetraisopropoxide (11.1 g) was added with stirring during the heating.

[0047] After the start of boiling, the azeotropic mixture of ethyl acrylate and ethanol was continuously distilled off at a reflux ratio of 10:1 adjusted during the reaction. The sample temperature rose to 100 °C during the reaction, and the vacuum was adjusted down to 500 mbar. Distillate and sample aliquots were taken periodically to monitor the progress of the reaction. To accelerate the reaction, the catalyst was gradually increased and added during the reaction (total 15.5 g). After 11.5 hours of distillation, the yield was over 98%.

[0048] 250 ml of water was added to the reaction mixture, and after stirring for 1 hour at a bath temperature of 75 °C, water and ethyl acrylate were distilled off. During the distillation, the pressure dropped to 12 mbar.

[0049] 44 g of filter aid Harbolite 900 was added to the reaction mixture and filtered through a pressure filter.

[0050] After filtration, the product was obtained with a purity of 96.3 GC area% and a yield of 1161 g.

[0051] Example 5 A 4L double-jacket reactor equipped with a column (Montz A3-750 packing), a cooler, a reflux splitter, a three-stage cross-arm agitator, and an air introduction section was charged with ethyl acrylate (2502 g), MeHQ (1.38 g), and solketal (1035 g). While introducing air, the mixture was heated to a sample temperature of 70 °C at 300 mbar, and 443 g of ethyl acrylate was distilled off. At 600 mbar, the sample temperature was raised to 90 °C, and titanium tetraethylate (9.8 g) was added during heating. Thereafter, the ethyl acrylate-ethanol azeotrope was distilled off starting with a reflux ratio of 10:3. The reflux ratio was adjusted during the reaction. During the reaction, the sample temperature rose to 95 °C, and the vacuum was adjusted to 500 mbar. Distillate and sample aliquots were taken periodically to monitor the progress of the reaction. To accelerate the reaction, the catalyst was gradually increased and added during the reaction (total 13.1 g). After 9.5 hours of distillation, the yield was over 98%. 260 ml of water was added to the reaction mixture, and after stirring for 1 hour at 80 °C, water and ethyl acrylate were distilled off. During the distillation, the pressure dropped to 15 mbar. 46 g of filter aid Harbolite 900 was added to the reaction mixture and filtered through a pressure filter.

[0052] After filtration, the product was obtained with a purity of 95.8 GC area% and a yield of 1247 g.

[0053] Example 6 A 4L double-jacket reactor equipped with a column (Montz A3-750 packing), a cooler, a reflux splitter, a three-stage cross-arm agitator, and a dilute air introduction section was charged with ethyl acrylate (2000 g), ethyl acrylate-ethanol azeotrope (190 g) from a previous experiment, MeHQ (1.27 g), and solketal (1000 g). While introducing air, the mixture was heated to a sample temperature of 86 °C at 600 mbar, and titanium tetraethylate (10.4 g) was added with stirring during the heating. After the start of boiling, the azeotropic mixture of ethyl acrylate and ethanol was continuously distilled off at a reflux ratio of 10:2 adjusted during the reaction. The sample temperature rose to 94 °C during the reaction, and the vacuum was adjusted down to 500 mbar. Distillate and sample aliquots were taken periodically to monitor the progress of the reaction. To accelerate the reaction, the catalyst was gradually increased and added during the reaction (total 11.7 g). After 10 hours of distillation, the yield was over 98%. At a temperature of 80 - 100 °C, the pressure was slowly reduced to 40 mbar to distill off ethyl acrylate. Then, while introducing 2 - 8 L / h of air, the temperature was maintained at 80 °C for an additional 5 hours until the concentration of ethyl acrylate in the solution was less than 0.01% (controlled by gas chromatography). 250 ml of water was added to the reaction mixture, stirred at 75 °C for 1 hour, and then the water was distilled off. During the distillation, the pressure dropped to 12 mbar. 44 g of filter aid Harbolite 900 was added to the reaction mixture and filtered through a pressure filter.

[0054] After filtration, the product was obtained with a purity of 96.0 GC area % and a yield of 1204 g.

Claims

1. A method for preparing sorbitol ketal acrylate by transesterifying ethyl acrylate with sorbitol ketal, comprising: (i) reacting ethyl acrylate with sorbitol ketal in the presence of a catalyst containing titanium (IV) or zirconium (IV) and a stabilizer in the presence of ethyl acrylate as an azeotropic agent that forms an azeotrope with ethanol; (ii) continuously distilling off and condensing an azeotrope containing ethyl acrylate and ethanol using a distillation column operated under reflux conditions; wherein steps (i) and (ii) are carried out simultaneously until the sorbitol ketal conversion rate reaches 95% or more, and step (ii) is carried out by diluting the condensed azeotrope with additional ethyl acrylate and using this mixture as reflux to the distillation column. A method characterized by the above.

2. The method according to claim 1, wherein the ethanol content of the reflux during the execution of steps (i) and (ii) is in the range of 10 to 30% by weight.

3. The method according to claim 1 or 2, wherein the reflux:distillate reflux ratio in the distillation column is 10:1 to 2:

1.

4. The method according to any one of claims 1 to 3, wherein steps (i) and (ii) are carried out at a pressure of 400 to 600 mbar and a temperature of 80 to 105 °C.

5. Step (iii): (iii) evaporating unreacted ethyl acrylate from the product mixture under evaporation conditions when the sorbitol ketal conversion rate reaches 95% or more. The method according to any one of claims 1 to 4, characterized by including the above step.

6. The method according to claim 5, wherein step (iii) is carried out when the sorbitol ketal conversion rate reaches 97% or more.

7. The method according to claim 5 or 6, wherein step (iii) is carried out at a pressure of 10 to 500 mbar and a temperature of 60 to 100 °C.

8. Step (iv): (iv) stripping the remaining ethyl acrylate from the product mixture using a gas stream. The method according to any one of claims 1 to 7, characterized by including the above step.

9. The method according to claim 8, wherein step (iv) is carried out until the ethyl acrylate concentration in the product mixture becomes 200 ppm or less.

10. Steps (v) to (vii): ​ Step (v): adding water to the product mixture containing sor ketal acrylate and the catalyst Step (vi): distilling off water from the product mixture Step (vii): removing the hydrolysis product of the catalyst containing titanium (IV) or zirconium (IV) comprising The method according to any one of claims 1 to 9, wherein step (vii) can also be carried out before step (vi). **Claim 11** Steps (v) to (vii): Step (v): adding water to the product mixture containing sor ketal acrylate and the catalyst Step (vi): distilling off water from the product mixture Step (vii): removing the hydrolysis product of the catalyst containing titanium (IV) or zirconium (IV) comprising The method according to any one of claims 1 to 9, wherein step (v) is carried out before step (iii). **Claim 12** The method according to claim 11, wherein step (vi) is carried out together with step (iii). **Claim 13** Steps (v) to (vii): Step (v): adding water to the product mixture containing sor ketal acrylate and the catalyst Step (vi): distilling off water from the product mixture Step (vii): removing the hydrolysis product of the catalyst containing titanium (IV) or zirconium (IV) comprising The method according to claim 8 or 9, wherein steps (v) and (vi) are carried out before step (iv). **Claim 14** The method according to any one of claims 1 to 13, wherein the catalyst contains titanium (IV) tetraisopropoxide. **Claim 15** The method according to any one of claims 1 to 14, wherein the stabilizer is selected from hydroquinone monomethyl ether and phenothiazine.

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