Patent Description:
A <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane has in one molecule thereof a <NUM>,<NUM>-substituted carbon-carbon unsaturated bond applicable to radical addition reaction, hydrosilylation reaction, hydroformylation reaction, and the like, and two acyl groups applicable to saponification reaction, ester exchange reaction, and the like, and thereby can be used as a production raw material of various chemical products due to the reactivity thereof (see, for example, PTLs <NUM> and <NUM>).

Some production methods of a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane have been known.

For example, NPL <NUM> describes a method for producing <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane through reaction of <NUM>,<NUM>-dichloro-<NUM>-methylenepropane and sodium acetate.

However, the production method generates an inorganic by-product, which generally becomes a waste material, in the equimolar amount or more with respect to the product. Accordingly, a production method that does not generate an inorganic by-product is demanded from the standpoint of the reduction of environmental load.

As a production method that does not generate an inorganic by-product, a method for producing a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane through reaction of a terminal olefin compound, a carboxylic acid, and oxygen in a gas phase in the presence of a solid catalyst has been known.

For example, PTL <NUM> describes a method for producing <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane through reaction of methallyl acetate, acetic acid, water, and oxygen in a gas phase in the presence of the particular catalyst. PTL <NUM> describes that a mixed gas of nitrogen/oxygen/methallyl acetate/acetic acid/water = <NUM>/<NUM>/<NUM>/<NUM>/<NUM> (mol/hr) is fed to <NUM> of the solid catalyst at <NUM> KPa (<NUM> atm) to perform gas phase reaction at a reaction temperature of <NUM>, and thereby <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane is obtained with a conversion of methallyl acetate of <NUM>% and a selectivity of <NUM>% (the production efficiency of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane is <NUM>/(L(catalyst)·hr).

PTL <NUM> describes a method for producing <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane through reaction by feeding a mixed gas containing isobutylene, acetic acid, and oxygen to a palladium catalyst in a gas phase, and describes that methallyl acetate by-produced is recycled and added to the reaction gas. PTL <NUM> describes that a mixed gas of acetic acid/oxygen/isobutylene/methallyl acetate/steam = <NUM>/<NUM>/<NUM>/<NUM>/<NUM> is fed at a rate of <NUM> per hour to <NUM> of the solid catalyst to perform gas phase reaction at a reaction temperature of <NUM>, and thereby <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane is obtained with a production efficiency of <NUM>/(L(catalyst)·hr).

A method for producing an unsaturated ester through reaction of a terminal olefin compound, a carboxylic acid, and oxygen in a liquid phase in the presence of a solid catalyst has been known.

For example, PTL <NUM> describes a method for producing methallyl acetate through reaction of isobutylene, acetic acid, and oxygen in the presence of a solid catalyst having an element composition shown by XaYb (wherein X represents at least one of Pd, Pt, and Rh, Y represents at least one of Bi, Sb, S, Te, V, and Nb, and <NUM> < b < <NUM> assuming a = <NUM>). PTL <NUM> describes that <NUM> of acetic acid, <NUM> of a hydrocarbon mixture containing <NUM>% of isobutylene, and oxygen gas are subjected to liquid phase reaction at a reaction temperature of <NUM> in the presence of <NUM> of the particular solid catalyst, and thereby methallyl acetate is obtained with a selectivity of <NUM>% and a conversion of isobutylene of <NUM>%, but there is no description about the production of a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane.

PTL <NUM> describes a method for producing methallyl acetate through reaction of isobutylene, acetic acid, triethyl phosphate, and oxygen in the presence of a titania-supported palladium-gold catalyst. <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane was obtained as a side product.

PTL <NUM> describes a method for producing vinylic and allylic monoacetates as well as vinylic and allylic diacetates through reaction of isobutylene, acetic acid, sulfolane, sodium acetate, and oxygen in the presence of a palladium-on-carbon catalyst.

All the ordinary methods for producing a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane that do not generate an inorganic by-product use reaction under the gas phase condition. In the reaction under the gas phase condition, the oxygen concentration is necessarily the critical oxygen concentration or lower from the standpoint of safety, which constrains an operation with a low substrate conversion, requiring a recovery device for the substrate. Furthermore, the reaction requires a vaporizer of the raw materials, a reaction tube filled with the catalyst, and an enormous amount of energy for vaporizing the raw materials, and therefore there is large room for improvement in all the standpoints of the production efficiency, the equipment cost, and the energy consumption.

In view of the circumstances, a problem to be solved by the present invention is to provide a method for producing a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane that does not generate an inorganic by-product in the equimolar amount or more with respect to the product and is improved in production efficiency and cost.

As a result of the earnest investigations for solving the problem, the present inventors have found that the problem can be solved by employing a particular liquid phase condition in the production of a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane through oxidative reaction of isobutylene and a carboxylic acid, and the present invention has been completed by performing further investigations based on the knowledge.

Specifically, the present invention is defined in the appended claims.

According to the present invention, a method for producing a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane that does not generate an inorganic by-product in the equimolar amount or more with respect to the product and is improved in production efficiency and cost can be provided.

While preferred embodiments of the present invention will be described along with the matters defining the present invention, an embodiment combining two or more of the individual preferred embodiments is also a preferred embodiment of the present invention. In the case where there are plural numeral ranges for the matter shown by a numeral range, a combination of the lower limit and the upper limit that are selected from the plural ranges may also be a preferred embodiment.

The method for producing the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane represented by the general formula (II) (which may be hereinafter abbreviated as a "<NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II)") of the present invention includes reacting the carboxylic acid represented by the general formula (I) (which may be hereinafter abbreviated as a "carboxylic acid (I)"), isobutylene, and oxygen, in the presence of a catalyst containing a carrier having carried thereon palladium and a transition metal of Group <NUM> in the periodic table, and a catalyst activator, in a liquid phase.

In the reaction, formally, one equivalent of isobutylene and two equivalents of the carboxylic acid (I) undergo oxidative dehydration condensation, so as to form the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) and water.

The reaction formula in a preferred embodiment of the present invention is as follows.

In the formula, R has the same meaning as R in the general formulae (I) and (II).

In the production method of the present invention, the costs of energy and equipment can be suppressed by employing the reaction under a liquid phase condition.

As a result of the investigations by the present inventors, it has been found that in a gas phase condition, the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) as the product is adsorbed on the catalyst and inhibits the reaction, and the deactivation of the catalyst occurs at a high temperature for retaining the gaseous state of the product, due to the high boiling point thereof. Accordingly, it is difficult to enhance the productivity in a gas phase condition, and a liquid phase condition is advantageous from the standpoint of the production efficiency.

In the general formula (I) representing the carboxylic acid as the raw material and the general formula (II) representing the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane as the target product, R represents a hydrogen atom, an alkyl group having <NUM> to <NUM> carbon atoms, which may have a substituent, a cycloalkyl group having <NUM> to <NUM> carbon atoms, which may have a substituent, an alkenyl group having <NUM> to <NUM> carbon atoms, which may have a substituent, or an aryl group having <NUM> to <NUM> carbon atoms, which may have a substituent.

The alkyl group having <NUM> to <NUM> carbon atoms represented by R may be linear or branched, and examples thereof include a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, a n-hexyl group, and a n-octyl group.

In the alkyl group having <NUM> to <NUM> carbon atoms represented by R, one or more hydrogen atom may be substituted by a substituent. Examples of the substituent include a cycloalkyl group having <NUM> to <NUM> carbon atoms, an aryl group having <NUM> to <NUM> carbon atoms, an alkoxy group having <NUM> to <NUM> carbon atoms, an aryloxy group having <NUM> to <NUM> carbon atoms, and a silyl group. In the case where the alkyl group having <NUM> to <NUM> carbon atoms represented by R has a substituent, the number of the substituent is preferably <NUM> to <NUM>. In the case where the alkyl group having <NUM> to <NUM> carbon atoms represented by R has plural substituents, the substituents may be the same as or different from each other.

Examples of the cycloalkyl group having <NUM> to <NUM> carbon atoms as the substituent include the same ones as exemplified for the cycloalkyl group having <NUM> to <NUM> carbon atoms represented by R described later.

Examples of the aryl group having <NUM> to <NUM> carbon atoms as the substituent include the same ones as exemplified for the aryl group having <NUM> to <NUM> carbon atoms represented by R described later.

Examples of the alkoxy group having <NUM> to <NUM> carbon atoms as the substituent include linear, branched, and cyclic alkoxy groups, such as a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, a pentyloxy group, a cyclopentyloxy group, a hexyloxy group, a cyclohexyloxy group, a <NUM>-ethylhexyloxy group, and an octyloxy group.

Examples of the aryloxy group having <NUM> to <NUM> carbon atoms as the substituent include a phenoxy group and a naphthoxy group.

Examples of the silyl group as the substituent include a trimethylsilyl group, a triethylsilyl group, a t-butyldimethylsilyl group, a t-butyldiphenylsilyl group, and a triphenylsilyl group.

The cycloalkyl group having <NUM> to <NUM> carbon atoms represented by R may be any of monocyclic, polycyclic, and condensed ring, and examples thereof include a cyclopropyl group, a cyclopentyl group, and a cyclohexyl group.

In the cycloalkyl group having <NUM> to <NUM> carbon atoms represented by R, one or more hydrogen atom may be substituted by a substituent. Examples of the substituent include an alkyl group having <NUM> to <NUM> carbon atoms that is the same as the examples of the alkyl group having <NUM> to <NUM> carbon atoms represented by R described above, a cycloalkyl group having <NUM> to <NUM> carbon atoms that is the same as the examples of the cycloalkyl group having <NUM> to <NUM> carbon atoms represented by R described above, and an aryl group having <NUM> to <NUM> carbon atoms, an alkoxy group having <NUM> to <NUM> carbon atoms, an aryloxy group having <NUM> to <NUM> carbon atoms, and a silyl group that are the same as the examples of the substituent described above. In the case where the cycloalkyl group having <NUM> to <NUM> carbon atoms represented by R has a substituent, the number of the substituent is preferably <NUM> to <NUM>. In the case where the cycloalkyl group having <NUM> to <NUM> carbon atoms represented by R has plural substituents, the substituents may be the same as or different from each other.

Examples of the alkenyl group having <NUM> to <NUM> carbon atoms represented by R include an ethenyl group (vinyl group), a <NUM>-methylethenyl group, a <NUM>-propenyl group, a <NUM>-propenyl group (allyl group), a <NUM>-methyl-<NUM>-propenyl group, a <NUM>-methyl-<NUM>-propenyl group, a <NUM>-butenyl group, a <NUM>-butenyl group, and a <NUM>-butenyl group.

In the alkenyl group having <NUM> to <NUM> carbon atoms represented by R, one or more hydrogen atom may be substituted by a substituent. Examples of the substituent include the same ones as exemplified for the substituent that may be had in the case where R represents an alkyl group having <NUM> to <NUM> carbon atoms. In the case where the alkenyl group having <NUM> to <NUM> carbon atoms represented by R has a substituent, the number of the substituent is preferably <NUM> to <NUM>. In the case where the alkenyl group having <NUM> to <NUM> carbon atoms represented by R has plural substituents, the substituents may be the same as or different from each other.

The aryl group having <NUM> to <NUM> carbon atoms represented by R may be any of monocyclic, polycyclic, and condensed ring, and examples thereof include a phenyl group, a naphthyl group, an anthryl group, and a phenanthryl group.

In the aryl group having <NUM> to <NUM> carbon atoms represented by R, one or more hydrogen atom may be substituted by a substituent. Examples of the substituent include the same ones as exemplified for the substituent that may be had in the case where R represents a cycloalkyl group having <NUM> to <NUM> carbon atoms. In the case where the aryl group having <NUM> to <NUM> carbon atoms represented by R has a substituent, the number of the substituent is preferably <NUM> to <NUM>. In the case where the aryl group having <NUM> to <NUM> carbon atoms represented by R has plural substituents, the substituents may be the same as or different from each other.

From the standpoint of the availability, R preferably represents an alkyl group having <NUM> to <NUM> carbon atoms or an alkenyl group having <NUM> to <NUM> carbon atoms, more preferably one selected from the group consisting of a methyl group, an ethyl group, a n-propyl group, a <NUM>-propyl group, a n-butyl group, a <NUM>-butyl group, an isobutyl group, an ethenyl group, and a <NUM>-methylethenyl group, further preferably a methyl group or a <NUM>-methylethenyl group, and most preferably a methyl group. Accordingly, the carboxylic acid (I) is most preferably acetic acid, and the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) is most preferably <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane.

The catalyst used in the production method of the present invention is a catalyst containing a carrier having carried thereon palladium and a transition metal of Group <NUM> in the periodic table. The catalyst may be a commercially available product and may be synthesized by a known method.

The carrier used may be, for example, a porous substance. Examples of the carrier include an inorganic carrier, such as silica, alumina, silica-alumina, diatom earth, montmorillonite, zeolite, titania, zirconia, and activated carbon; and a polymer compound, such as polystyrene, polyethylene, polyamide, and cellulose. These may be used alone or as a combination of two or more kinds thereof. Among these, an inorganic carrier is preferred, silica or alumina is more preferred, and silica is further preferred. Silica may contain impurities other than SiO<NUM>.

The form of the carrier is not particularly limited, and may be appropriately selected depending on the reaction mode. Specific examples of the form thereof include a powder form, a spherical form, and a pellet form, and a spherical form is preferred. In the case where the carrier has a spherical form, the particle diameter is not particularly limited, and is preferably <NUM> to <NUM>. In the case where the particle diameter is <NUM> or less, the raw materials can readily penetrate sufficiently into the interior of the catalyst, and the reaction can readily proceed effectively. In the case where the particle diameter is <NUM> or more, the carrier can readily exhibit the function thereof sufficiently.

The catalyst used contains the carrier having palladium carried thereon. Palladium herein may be in the form of metallic palladium or a palladium compound. The palladium compound is not particularly limited, and examples thereof include palladium chloride, palladium acetate, palladium nitrate, palladium sulfate, sodium chloropalladate, potassium chloropalladate, and barium chloropalladate.

The carrier further has a transition metal of Group <NUM> in the periodic table, such as copper and gold, carried thereon, in addition to palladium described above. The transition metals may be used alone or as a combination of two or more kinds thereof. Among these, copper and gold are preferred, and gold is more preferred, from the standpoint of the enhancement of the production efficiency. The use form of the transition metal of Group <NUM> in the periodic table in the preparation of the catalyst is not particularly limited, and examples of the form include compound forms, such as a nitrate salt, a carbonate salt, a sulfate salt, an organic acid salt, and a halide.

The ratio of palladium and the transition metal of Group <NUM> in the periodic table is preferably <NUM> to <NUM> parts by mass, and more preferably <NUM> to <NUM> parts by mass, of the transition metal of Group <NUM> in the periodic table per <NUM> part by mass of palladium.

The preparation method of the catalyst containing a carrier having palladium and a transition metal of Group <NUM> in the periodic table carried thereon is not particularly limited, and for example, the catalyst may be obtained by performing sequentially the following steps (<NUM>) to (<NUM>).

Step of impregnating a carrier with an aqueous solution of a palladium salt and a compound containing a transition metal of Group <NUM> in the periodic table, so as to provide a catalyst precursor A.

Step of bringing the catalyst precursor A obtained in the step (<NUM>) without drying, into contact with an aqueous solution of an alkali metal salt, so as to provide a catalyst precursor B.

Step of bringing the catalyst precursor B obtained in the step (<NUM>), into contact with a reducing agent, such as hydrazine or formalin, so as to provide a catalyst precursor C.

Step of rinsing with water and drying the catalyst precursor C obtained in the step (<NUM>).

The catalyst obtained by the aforementioned preparation method preferably has a specific surface area of <NUM> to <NUM><NUM>/g and a pore volume of <NUM> to <NUM>/g.

The ratio of palladium and the carrier in the catalyst is preferably <NUM> to <NUM>,<NUM> parts by mass, and more preferably <NUM> to <NUM> parts by mass, of the carrier per <NUM> part by mass of palladium. In the case where the amount of the carrier is <NUM> parts by mass or more per <NUM> part by mass of palladium, the dispersion state of palladium can be enhanced to improve the reaction result. In the case where the amount of the carrier is <NUM>,<NUM> parts by mass or less per <NUM> part by mass of palladium, the industrial practicality can be enhanced.

The amount of the catalyst used in the production method of the present invention is not particularly limited, and is preferably <NUM> to <NUM>% by mass, more preferably <NUM> to <NUM>% by mass, further preferably <NUM> to <NUM>% by mass, and still further preferably <NUM> to <NUM>% by mass, based on the total mass of the carboxylic acid (I) and isobutylene, from the standpoint of the enhancement of the production efficiency.

The catalyst activator used in the production method of the present invention may be used in the form carried on the catalyst in advance, or may be charged in the reaction device along with the reaction mixture. The catalyst activator is a carboxylate salt of an alkali metal, such as sodium, potassium, and cesium; or a carboxylate salt of an alkaline earth metal, such as magnesium, calcium, and barium. These catalyst activators may be used alone or as a combination of two or more kinds thereof. A salt of the carboxylic acid (I) is preferred, an alkali metal salt of the carboxylic acid (I) is more preferred, and potassium acetate is further preferred, from the standpoint of the availability and the reaction activity.

The amount of the catalyst activator used is not particularly limited, and is preferably <NUM> to <NUM>% by mass, and more preferably <NUM> to <NUM>% by mass, based on the total amount of the mass of the carrier and the amount of the catalyst activator used as <NUM>% by mass.

Oxygen used in the production method of the present invention may be atomic and/or molecular oxygen, and is preferably molecular oxygen. In the case where molecular oxygen is used, a mixed gas with an inert gas, such as nitrogen, argon, helium, and carbon dioxide, is preferably used. In this case, it is more preferred that the oxygen concentration is controlled to such a range that the gas inside the system does not have an explosive composition.

Examples of the method of supplying molecular oxygen or a mixed gas containing molecular oxygen to the reaction system include a method of supplying to the liquid phase portion in the reaction system, a method of supplying to the gas phase portion therein, and a method of supplying to both the liquid phase portion and the gas phase portion.

Molecular oxygen or a mixed gas containing molecular oxygen is preferably supplied to the reaction system at an oxygen partial pressure in a range of <NUM> KPa to <NUM> MPa (<NUM> to <NUM> atm, gauge pressure), and more preferably <NUM> KPa to <NUM> MPa (<NUM> to <NUM> atm, gauge pressure).

The reaction of the carboxylic acid (I), isobutylene, and oxygen in the presence of the catalyst and the catalyst activator in a liquid phase in the production method of the present invention may be performed by using a solvent or without a solvent.

Examples of the solvent that is used depending on necessity in the production method of the present invention include a hydrocarbon (including an aliphatic hydrocarbon and an aromatic hydrocarbon), such as hexane, heptane, methylcyclohexane, and benzene; a heterocyclic compound, such as pyridine and quinoline; an ether, such as diethyl ether, tetrahydrofuran, methyl tert-butyl ether, and cyclopentyl methyl ether; a ketone, such as acetone, methyl ethyl ketone, and isobutyl methyl ketone; an ester, such as a carboxylate ester, diethyl carbonate, and propylene carbonate; an amide, such as dimethylformamide and dimethylacetamide; a nitrile, such as acetonitrile and benzonitrile; and an alcohol, such as methanol, ethanol, isopropyl alcohol, and phenol. These may be used alone or as a combination of two or more kinds thereof.

In the case where a solvent is used in the reaction, the amount of the solvent used is not particularly limited, as far as the reaction is not adversely affected, and is generally approximately <NUM> to <NUM>,<NUM> times amount, and is preferably <NUM> to <NUM> times amount from the standpoint of the productivity, all based on the total mass of the carboxylic acid (I) and isobutylene.

In the production method of the present invention, the amount of the carboxylic acid (I) used (i.e., the amount thereof used per <NUM> mol of the isobutylene) is <NUM> mol or more, or <NUM> mol or more and <NUM> mol or less, preferably <NUM> mol or less, more preferably <NUM> mol or less, and further preferably <NUM> mol or less. In the case where the amount thereof used is <NUM> mol or more, a further excellent production efficiency can be obtained. In the case where the amount thereof used is <NUM> mol or less, the process for recovering the excessive carboxylic acid (I) can be shortened, which is economically advantageous.

In the case where the carboxylic acid (I) is placed in the reaction system by dividing into multiple times, the amount thereof used is the total amount thereof placed.

The reaction conditions, such as the reaction temperature, the reaction pressure, and the reaction time, in the production method of the present invention may be appropriately determined depending on the kinds and the combination of the carboxylic acid (I), isobutylene, and the solvent used depending on necessity, the composition of the catalyst, and the like, and are not particularly limited.

For example, the reaction temperature is preferably in a range of <NUM> to <NUM>. In the case where the reaction temperature is <NUM> or more, the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) can be efficiently produced without excessive decrease of the reaction rate. The reaction temperature is more preferably <NUM> or more, and further preferably <NUM> of more. In the case where the reaction temperature is <NUM> or less, side reaction including combustion can be prevented from occurring, and thereby the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) can be efficiently produced, and the corrosion of the reaction device due to the carboxylic acid can be suppressed. The reaction temperature is more preferably <NUM> or less, and further preferably <NUM> or less.

The reaction time may be in a range, for example, of <NUM> to <NUM> hours. The reaction time may be <NUM> hour or more from the standpoint of the production efficiency, and may be <NUM> hours or less or <NUM> hours or less from the same standpoint.

The reaction mode in the production method of the present invention may be either a continuous system or a batch system, and is not particularly limited. In the case where a batch system is used as the reaction mode, for example, the catalyst may be charged in the reaction device at one time along with the raw materials, and in the case where a continuous system is used as the reaction mode, for example, the catalyst may be charged in the reaction device in advance, or may be continuously charged in the reaction device along with the raw materials. The catalyst may be used in the form of any of a fixed bed, a fluidized bed, and a suspension bed.

In the production method of the present invention, purification may be performed after the aforementioned reaction. Specifically, the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) formed through the aforementioned reaction can be isolated by separating the catalyst and then purifying the reaction solution.

The measure for separating the catalyst is not particularly limited and may be an ordinary solid-liquid separation measure, and examples thereof used include filtration methods, such as natural filtration, pressure filtration, filtration under reduced pressure, and centrifugal filtration.

The measure for purifying the reaction solution is not particularly limited and may be a distillation method, an extraction method, column chromatography, or the like. These methods may be performed in combination. Among these, a distillation method and an extraction method are preferred.

The raw materials and the solvent separated by the purification may be used again for the reaction. The catalyst separated may also be used again in the reaction.

The production method of the present invention exemplified by the aforementioned embodiments can produce the <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane (II) as the target product with a high conversion, a high selectivity, and a high yield, without the formation of the inorganic by-product in the equimolar amount or more with respect to the target product.

The present invention will be described more specifically with reference to an example and comparative examples below, but the present invention is not limited thereto.

The solution after the reaction (reaction mixture) was analyzed by using a gas chromatograph GC2014 (produced by Shimadzu Corporation, FID detector) and a capillary column (produced by Agilent Technologies, Inc. , DB-<NUM>, length: <NUM>, inner diameter: <NUM>, thickness: <NUM> pm) under the following condition.

<NUM> (<NUM>) of a silica carrier (<NUM> in diameter) was immersed in an aqueous solution containing <NUM> (<NUM> mmol) of sodium tetrachloropalladate and <NUM> (<NUM> mmol) of tetrachloroauric acid tetrahydrate, and the entire amount of the aqueous solution was absorbed thereby. Subsequently, <NUM> of an aqueous solution containing <NUM> (<NUM> mmol) of sodium metasilicate was added thereto, and the mixture was allowed to stand for <NUM> hours. Thereafter, <NUM> (<NUM> mmol) of hydrazine monohydrate was added to reduce the palladium salt and the gold salt to metals. The catalyst after the reduction was rinsed with water and dried at <NUM> for <NUM> hours. Thereafter, the carrier having metallic palladium was placed in an aqueous solution containing <NUM> (<NUM> mmol) of potassium acetate, the entire amount of the aqueous solution was absorbed thereby, and then dried at <NUM> for <NUM> hours to prepare the catalyst <NUM>.

<NUM> (<NUM>) of a silica carrier (<NUM> in diameter) was immersed in an aqueous solution containing <NUM> (<NUM> mmol) of sodium tetrachloropalladate and <NUM> (<NUM> mmol) of tetrachloroauric acid tetrahydrate, and the entire amount of the aqueous solution was absorbed thereby. Subsequently, <NUM> of an aqueous solution containing <NUM> (<NUM> mmol) of sodium metasilicate was added thereto, and the mixture was allowed to stand for <NUM> hours. Thereafter, <NUM> (<NUM> mmol) of hydrazine monohydrate was added to reduce the palladium salt and the gold salt to metals. The catalyst after the reduction was rinsed with water and dried at <NUM> for <NUM> hours to prepare the catalyst <NUM>.

<NUM> of the catalyst <NUM> obtained in Production Example <NUM>, <NUM> (<NUM> mmol) of acetic acid, and <NUM> (<NUM> mmol) of isobutylene were charged in an electromagnetic stirring autoclave having a capacity of <NUM> equipped with a gas inlet port and a sampling port, a mixed gas of oxygen/nitrogen = <NUM>/<NUM> (molar ratio) was introduced to the liquid phase to make the pressure inside the autoclave of <NUM> MPa (<NUM> atm, gauge pressure), and then the temperature in the autoclave was increased to <NUM> under stirring. Thereafter, the reaction was performed for <NUM> hours while flowing a mixed gas of oxygen/nitrogen = <NUM>/<NUM> (molar ratio) at a flow rate of <NUM>/min and retaining <NUM> MPa (<NUM> atm, gauge pressure) with the mixed gas, so as to provide a reaction solution.

The analysis of the resulting reaction solution by the aforementioned method revealed that the conversion of isobutylene was <NUM>%, and the selectivity to <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane was <NUM>%. The yield of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane obtained was <NUM> (<NUM> mmol), and the production efficiency of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane was <NUM>(product)/(g(catalyst)·hr).

The reaction was performed by performing the same procedure as in Example <NUM> except that the catalyst <NUM> was used instead of the catalyst <NUM>, and the reaction was performed for <NUM> hours.

The analysis of the resulting reaction solution by the aforementioned method revealed that the conversion of isobutylene was <NUM>%, the selectivity to <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane was <NUM>%, and the selectivity to methallyl acetate was <NUM>%. The yield of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane obtained was <NUM> (<NUM> mmol), and the production efficiency of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane was <NUM>(product)/(g(catalyst)·hr).

<NUM> (approximately <NUM>) of the catalyst <NUM> obtained in Production Example <NUM> was packed in a reaction tube formed of stainless steel having an inner diameter of <NUM> and a length of <NUM>, through which isobutylene, acetic acid, oxygen, nitrogen, and water were loaded at a volume ratio (in terms of gas) of isobutylene/acetic acid/oxygen/nitrogen/water = <NUM>/<NUM>/<NUM>/<NUM>/<NUM> and a rate of <NUM> NL/hr, and reacted under pressure of <NUM> MPaG at <NUM>. After <NUM> hours, the analysis of the composition in the outlet port of the reaction tube revealed that the production rates of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane and methallyl acetate were <NUM>(product)/(g(catalyst)·hr) and <NUM>(product)/(g(catalyst)·hr) respectively, and the yields of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane and methallyl acetate with respect to isobutylene loaded to the reaction tube were <NUM>% and <NUM>% respectively. Carbon dioxide was generated at a selectivity of <NUM>% with respect to isobutylene reacted.

Thereafter, after loading only nitrogen at <NUM> under the atmospheric pressure at a rate of <NUM> NL/hr for <NUM> hour, the reaction tube was cooled to room temperature, and the catalyst was taken out therefrom. <NUM> of the catalyst was immersed in <NUM> of methanol, and the analysis of the solution confirmed the presence of <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane. Accordingly, it was found that <NUM>,<NUM>-diacetoxy-<NUM>-methylenepropane was not sufficiently vaporized but was adsorbed on the catalyst under the reaction condition.

The results of Example <NUM> and Comparative Examples <NUM> and <NUM> shown above are shown in Table <NUM>.

The expressions in Table <NUM> are as follows.

Example <NUM> shows an excellent selectivity, from which it is understood that an inorganic by-product is not formed in the equimolar amount or more with respect to the product. It is also understood from the conversion, the selectivity, and the yield that Examples are excellent in production efficiency as compared to Comparative Examples.

Claim 1:
A method for producing a <NUM>,<NUM>-bisacyloxy-<NUM>-methylenepropane represented by the following general formula (II), comprising reacting a carboxylic acid represented by the following general formula (I), isobutylene, and oxygen, in a liquid phase, in the presence of a catalyst containing a carrier having carried thereon palladium and a transition metal of Group <NUM> in the periodic table, and a catalyst activator:
<CHM>
wherein amount of the carboxylic acid used is <NUM> mol or more and <NUM> mol or less per <NUM> mol of the isobutylene, the catalyst activator is a carboxylate salt of an alkali metal or an alkaline earth metal, R represents a hydrogen atom, an alkyl group having <NUM> to <NUM> carbon atoms, which may have a substituent, a cycloalkyl group having <NUM> to <NUM> carbon atoms, which may have a substituent, an alkenyl group having <NUM> to <NUM> carbon atoms, which may have a substituent, or an aryl group having <NUM> to <NUM> carbon atoms, which may have a substituent.