CN1918105A - Process for producing alpha,beta-unsaturated carboxylic acid - Google Patents

Abstract

The object of the present invention is to provide a method for producing an alpha,beta-unsaturated carboxylic acid in higher selectivity. The present invention resides in a method for producing an alpha,beta-unsaturated carboxylic acid from an olefin or an alpha,beta-unsaturated aldehyde in liquid phase by using a noble metal-containing catalyst and by causing a compound (A) having an acid dissociation exponent (pKa) of less than 4 to be present in the liquid phase.

Description

α, the manufacture method of beta-unsaturated carboxylic acid

Technical field

The present invention relates to use the catalyzer that contains precious metal by alkene or α, beta-unsaturated aldehyde is made α, the method for beta-unsaturated carboxylic acid.

Background technology

As alkene or α, beta-unsaturated aldehyde is made α through the liquid-phase oxidation of molecularity oxygen, the method for beta-unsaturated carboxylic acid, the method for using the catalyzer that contains precious metal of having studied in vogue always.For example, disclose in the patent documentation 1～4 and used that to carry palladium containing metal catalyzer and carbon number be that 3～6 alkene contact and year palladium containing metal catalyzer of activatory after activating by making, utilized the method for molecularity oxygen the alkene liquid-phase oxidation.Particularly disclose in the patent documentation 2, tensio-active agent and alcohol are present in the reaction system, sought to improve α, the selectivity of beta-unsaturated carboxylic acid.Disclose in the patent documentation 3, made radical forbid that agent is present in the reaction system, sought to improve α, the selectivity of beta-unsaturated carboxylic acid.Disclose in the patent documentation 4 to use and comprised C ₂～C ₆Carboxylic acid, the trimethyl carbinol, or C ₃～C ₆The reaction solvent of ketone.Therefore, do not put down in writing acid dissociation exponent (pKa) in the patent documentation 1～4 less than 4 reaction solvent and additive.

Patent documentation 1: the spy opens clear 60-139341 communique

Patent documentation 2: the spy opens clear 60-139643 communique

Patent documentation 3: the spy opens clear 60-155148 communique

Patent documentation 4: the international international publication text that discloses No. 02/083299

Summary of the invention

But, that puts down in writing in using the embodiment of patent documentation 1～4 carries palladium containing metal catalyzer when propylene is made vinylformic acid, by product (acetaldehyde except record in the patent documentation 1～4, acetone, propenal, acetate, carbonic acid gas) in addition, vinylformic acid allyl ester, multiple polymers and oligopolymer have also been generated in a large number.In patent documentation 1～4, do not capture these polymkeric substance, oligopolymer, thereby comprise put down in writing among the embodiment of vinylformic acid selection rate than patent documentation 1～4 of reality of these by products low.Equally, from iso-butylene manufacturing methacrylic acid the time, owing to generated methacrylic acid methyl propenyl ester in a large number, multiple polymers, oligopolymer, thereby the selection rate of methacrylic acid is low.And then, along with the vinylformic acid that generates or the increase of methacrylic acid concentration, also increase as the acrylate of other by products or the amount of methacrylic ester.

Therefore, use the catalyzer of record in the patent documentation 1～4 to prepare α, the selection rate of the method for beta-unsaturated carboxylic acid is also insufficient, thereby, need prepare α, the method for beta-unsaturated carboxylic acid with high selectivity more.

The present invention relates to use the catalyzer that contains precious metal, from alkene or α, beta-unsaturated aldehyde is made α in liquid phase, and the method for beta-unsaturated carboxylic acid makes to exist acid dissociation exponent (pKa) less than 4 compound (A) in above-mentioned liquid phase.

Acid dissociation exponent among the present invention (pKa) is meant, the logarithmic value of the inverse of the dissociation constant of compound in the solution (HA), i.e. value in 25 ℃ of following infinite dilution aqueous solution.Concrete is meant, when the acid dissociation balanced reaction with HA shown in the following formula (1) takes place, and the numerical value of being tried to achieve by formula (2).

(1)

$\mathrm{pKa}=-\log \frac{\left[H^{+}\right]\left[A^{-}\right]}{\left[\mathrm{HA}\right]}---\left(2\right)$

For the compound that has twice above acid dissociation balanced reaction, the acid dissociation exponent of this compound (pKa) is meant the acid dissociation exponent in its acid dissociation balanced reaction for the first time.

Catalyzer by containing precious metal in use in liquid phase from alkene or α, beta-unsaturated aldehyde is made α, in the method for beta-unsaturated carboxylic acid, above-mentioned acid dissociation exponent (pKa) is present in the above-mentioned liquid phase less than 4 compound (A), selection rate that can be higher is made α, beta-unsaturated carboxylic acid.

Embodiment

In the present invention, contain the catalyzer (the following catalyzer that is called for short sometimes) of precious metal with alkene or α in use, beta-unsaturated aldehyde carries out liquid-phase oxidation and makes α, during beta-unsaturated carboxylic acid, is necessary to make acid dissociation exponent (pKa) to be present in the liquid phase less than 4 compound (A).If do like this, then can improve α, the selection rate of beta-unsaturated carboxylic acid.The acid dissociation exponent (pKa) of preferred compound (A) is smaller or equal to 3, is more preferably less than to equal 2.

As the addition of compound (A), preferably make the concentration of compound in the reaction soln (A) become 0.01 quality %～30 quality %.More preferably more than the 0.1 quality %, be preferably especially more than the 0.5 quality %.And, more preferably below the 20 quality %, be preferably especially below the 15 quality %.

, for example can enumerate less than 4 compound (A) as acid dissociation exponent (pKa), mineral compound, organic compound, huge legendary turtle are closed reagent etc., but wherein preferably have organic compounds, more preferably carboxylic acid cpd.Carboxylic acid cpd can be the aliphatic carboxylic acid compound, the aromatic carboxy acid compound, and also unsaturated carboxylic acid compound, unsaturated carboxylic acid compounds can be the monocarboxylic acid compound, also can be polycarboxylic acid compounds such as dicarboxylic acid compound.In addition,, also can use halogenated carboxylic acid, nitrogenous carboxylic acid cpd such as amino-acid compound, keto-earboxylic acid compound, hydroxy carboxylic acid compound as carboxylic acid cpd.

Specifically can enumerate, for example, aspartic acid (pKa=1.93), formic acid (pKa=3.55), citric acid (pKa=2.87), neighbour-chloro-benzoic acid (pKa=2.92), Mono Chloro Acetic Acid (pKa=2.68), dichloro acetic acid (pKa=1.30), trichoroacetic acid(TCA) (pKa=0.66), nicotinic acid (pKa=2.05), lactic acid (pKa=3.66), oxalic acid (pKa=1.04), picric acid (pKa=0.33), pyridine carboxylic acid (pKa=1.03), gifblaar poison (pKa=2.59), difluoroacetic acid (pKa=1.08), trifluoroacetic acid (pKa=0.30), phthalic acid (pKa=2.75), m-phthalic acid (pKa=3.50), terephthalic acid (pKa=3.54), toxilic acid (pKa=1.75), propanedioic acid (pKa=2.65) etc., wherein preferred Mono Chloro Acetic Acid, dichloro acetic acid, trichoroacetic acid(TCA), gifblaar poison, difluoroacetic acid, trifluoroacetic acid, toxilic acid, any one of propanedioic acid, preferred especially trifluoroacetic acid.These compounds (A) can use separately, also can two or morely share together.

Improve α by adding compound (A), though the reason of the selection rate of beta-unsaturated carboxylic acid it be unclear that, can infer has following reason.Can enumerate as first reason of inferring, compound (A) can promote by product α, the hydrolysis reaction of the ester that the same raw material of beta-unsaturated carboxylic acid, solvent reaction generate.Can enumerate as second reason inferring, compound (A) generates the ester of compound (A) with raw material reaction, the ester of the compound of gained (A) generates α through hydrolysis and oxidation, the such new reaction route of beta-unsaturated carboxylic acid preferentially carries out, the result has suppressed polymkeric substance, oligopolymer, the generation of by products such as ester.

In the present invention, further preferably making acid dissociation exponent (pKa) is that 2～6 carboxylic acid cpd (B) exists in liquid phase together with above-mentioned compound (A) more than or equal to 4 carbon number.If like this, can further improve α, the selection rate of beta-unsaturated carboxylic acid.

Be the addition of 2～6 carboxylic acid cpd (B) as carbon number, the concentration that preferably makes the carboxylic acid cpd (B) of carbon number 2～6 in the reaction soln is 1 quality %～70 quality %.More preferably more than the 2 quality %, be preferably especially more than the 4 quality %.And below the preferred 60 quality %, below the preferred especially 50 quality %.

's 2～6 carboxylic acid cpd (B) as acid dissociation exponent (pKa) more than or equal to 4 carbon number, for example can enumerate acetate (pKa=4.56), propionic acid (pKa=4.67), butanic acid (pKa=4.63), isopropylformic acid (pKa=4.63), positive valeric acid (pKa=4.64), isovaleric acid (pKa=4.58), n-caproic acid (pKa=4.63), succsinic acid (pKa=4.00), pentanedioic acid (pKa=4.13), hexanodioic acid (pKa=4.26) etc.In wherein preferred acetate, propionic acid, butanic acid, isopropylformic acid, the positive valeric acid any, preferred especially acetate.These carboxylic acid cpds (B) can use separately, also can two or more one reinstate.In addition, do not contain α in the carboxylic acid cpd (B), beta-unsaturated carboxylic acid as reaction product.

As the catalyzer that contains precious metal that uses among the present invention, can use the commercially available catalyzer that contains precious metal, also can use by making the compound that contains precious metal contact the catalyzer made from reductive agent.Under the situation of using the commercially available catalyzer that contains precious metal, preferably, the catalyzer that contains precious metal make its activation be applied to reaction again by being contacted with reductive agent.

Contained precious metal is meant in the catalyzer that contains precious metal that uses among the present invention, any in palladium, platinum, rhodium, ruthenium, iridium, gold and silver and the osmium, any in wherein preferred palladium, platinum, rhodium, ruthenium, iridium and the gold, preferred especially palladium.Also can contain two or more such precious metals.In containing the catalyzer of precious metal, also can contain precious metal metal in addition.

Usually, catalyzer is that the catalyzer component is supported on the carrier as catalyst-loaded use, but be not must use catalyst-loaded.As carrier, can enumerate, for example, gac, carbon black, silicon-dioxide, aluminum oxide, magnesium oxide, calcium oxide, titanium dioxide and zirconium white etc.Wherein, preferred gac, silicon-dioxide or aluminum oxide.Because the specific surface area of carrier according to kind of carrier etc. and different, cannot treat different things as the same, but for gac, is preferably 100m ²More than/the g, 300m more preferably ²More than/the g, be preferably 5000m ²Below/the g, 4000m more preferably ²Below/the g.The specific surface area of carrier is more little, may prepare the effective constituent catalyzer that support in the surface more more, and the specific surface area of carrier is big more, may prepare the catalyzer that supports the mass efficient composition more.

For catalyst-loaded, precious metal is preferably more than the 0.1 quality % of carrier quality before supporting, more preferably more than the 0.5 quality %, more preferably more than the 1 quality % with respect to the rate that supports of carrier; And be preferably below the 40 quality %, more preferably below the 30 quality %, and then be preferably below the 20 quality %.

Catalyst-loaded manufacture method is not particularly limited, and for example, can add reductive agent in the solution of the precious metal chemical complex that is dispersed with carrier and reduce, and makes precious metal be supported on liquid phase reduction on the carrier thus; Dry after noble metal compound solution being contained be immersed in the carrier, in the reducing gas atmosphere, reduce and the gas phase reduction process that supports precious metal is made.Wherein, preferred liquid phase reduction method.Non-catalyst-loaded manufacturing preferably adds reductive agent and carries out the reductive liquid phase reduction too in the solution of precious metal chemical complex.Below the method for utilizing liquid phase reduction to prepare catalyzer is described.

As the solvent that in liquid-phase reduction, uses, preferably water, but according to the solvability of precious metal chemical complex and reductive agent, and the dispersiveness of the carrier of carrier when using carrier, can be used alone or in combination alcohols such as ethanol, 1-propyl alcohol, 2-propyl alcohol, propyl carbinol, the trimethyl carbinol; Ketones such as acetone, methyl ethyl ketone, methyl iso-butyl ketone (MIBK), pimelinketone; Organic acids such as acetate, positive valeric acid, isovaleric acid; The organic solvent of hydro carbons such as heptane, hexane, hexanaphthene etc.

There is no particular limitation for the precious metal chemical complex that uses, preference as, the muriate of precious metal, oxide compound, acetate, nitrate, vitriol, tetramine complex compound, acetylacetonate complex etc., wherein, the more preferably muriate of precious metal, oxide compound, acetate, nitrate or vitriol, muriate, acetate or the nitrate of preferred especially precious metal.

Make when catalyst-loaded, with carrier and precious metal chemical complex according to desirable order or join in the solvent simultaneously, thereby preparation carrier dispersive noble metal compound solution.The concentration of the precious metal chemical complex of this solution is preferably more than the 0.1 quality %, more preferably more than the 0.2 quality %, is preferably especially more than the 0.5 quality %, and is preferably below the 20 quality %, more preferably below the 10 quality %, is preferably especially below the 7 quality %.Then, in this dispersion liquid, add reductive agent and make the precious metal reduction, thereby the precious metal after the reduction is supported on the carrier.Make non-ly when catalyst-loaded, the concentration of precious metal chemical complex also is preferably with above-mentioned manufacturing the same scope of concentration when catalyst-loaded.

There is no particular limitation for the reductive agent that uses, can enumerate, for example, hydrazine, formaldehyde, sodium borohydride, hydrogen, formic acid, formate, ethene, propylene, 1-butylene, 2-butylene, iso-butylene, 1,3-butadiene, 1-amylene, 2-amylene, 1-hexene, 2-hexene, tetrahydrobenzene, vinyl carbinol, methylallyl alcohol, propenal, Methylacrylaldehyde etc.These reductive agents can use separately also and can two or morely share.

When reductive agent was gas, in order to be increased in the solubleness in the solution, reaction was preferably carried out in pressurizing devices such as autoclave.At this moment, pressurize with reductive agent in pressurizing device inside.Its pressure is usually in 0.1～1MPa (pressure gauge pressure, pressure shown below is the pressure gauge pressure).The gas phase portion of pressurizing device preferably replaced with rare gas elementes such as nitrogen before importing reductive agent in advance.

In addition, when reductive agent was liquid, there is no particular limitation for carrying out precious metal reductive device, can be by reductive agent being joined the reduction of carrying out precious metal in the noble metal compound solution.At this moment, the usage quantity of reductive agent is not particularly limited, but with respect to 1 mole of precious metal chemical complex, is generally about 1～100 mole.

Reduction temperature and recovery time are according to the difference of employed precious metal chemical complex, reductive agent etc. and difference, but reduction temperature is preferably more than-5 ℃, more preferably more than 15 ℃.And reduction temperature is preferably below 150 ℃, more preferably below 80 ℃.Recovery time is preferably more than 0.1 hour, more preferably more than 0.25 hour, particularly preferably in more than 0.5 hour.And the recovery time is preferably below 4 hours, more preferably below 3 hours, particularly preferably in below 2 hours.

Want separate precious metal to support catalyst-loaded or unsupported catalysts on carrier after the reduction.The method of separating catalyst is not particularly limited, and for example can use, and filters methods such as centrifugation.Catalyzer after the separation can be suitably dry.Drying means is not particularly limited, and can make in all sorts of ways.

The amount of contained precious metal is below 10mg/l in the solvent after the preferred reduction.This amount can be by precious metal chemical complex before reducing concentration, reductive condition etc. regulate.In addition, the having or not of the precious metal in the solvent behind the separating catalyst, can confirm simply by adding reductive agent such as hydrazine.In addition, the amount of the precious metal in the solvent can be undertaken quantitatively by ultimate analyses such as ICP.

Catalyzer also can activate before supplying to liquid phase oxidation reaction.There is no particular limitation for the activatory method, can make in all sorts of ways.As the activatory method, be generally the method that under reducing atmosphere, heats in hydrogen stream.

The physical properties of prepared catalyzer can wait to determine by BET specific area measuring, XRD determining, CO pulse absorption method, tem observation.

Below, to alkene or α, beta-unsaturated aldehyde is made α through the liquid-phase oxidation of molecularity oxygen, and the method for beta-unsaturated carboxylic acid describes.

As the alkene of raw material, for example can enumerate propylene, iso-butylene, 2-butylene etc.In addition, as the α of raw material, beta-unsaturated aldehyde for example can be enumerated, propenal, Methylacrylaldehyde, crotonic aldehyde (Beta-methyl propenal), phenylacrolein (beta-phenyl propenal) etc.

Prepared α, beta-unsaturated carboxylic acid when raw material is alkene, is the α that has with alkene same carbon skeleton, beta-unsaturated carboxylic acid.In addition, be α at raw material, during beta-unsaturated aldehyde, be α, the aldehyde radical of beta-unsaturated aldehyde is changed to the α of carboxyl, beta-unsaturated carboxylic acid.

Manufacture method of the present invention is suitable for preparing vinylformic acid by propylene or propenal, prepares methacrylic acid by iso-butylene or Methylacrylaldehyde.

Raw material olefin or α in the beta-unsaturated aldehyde, can contain a spot of stable hydrocarbon and/or rudimentary saturated aldehyde etc. as impurity.

Used molecularity oxygen source in the liquid phase oxidation reaction, air is economical, but also available purity oxygen or pure oxygen as required, can use air or the pure oxygen mixed gas through dilutions such as nitrogen, carbonic acid gas, water vapour with Air mixing gas.

There is no particular limitation for solvent used in the liquid phase oxidation reaction, for example can use water; Alcohols such as the trimethyl carbinol, hexalin; Ketones such as acetone, methyl ethyl ketone, methyl iso-butyl ketone (MIBK); Organic acid ester such as ethyl acetate, methyl propionate; Hydro carbons such as hexane, hexanaphthene, toluene etc.Wherein, preferred carbon number is 3～6 ketone, the trimethyl carbinol.Solvent can use a kind of, also can use two or more mixed solvents.And, using alcohols, ketone and organic acid acetic time-like preferably use the mixed solvent of they and water.Be not particularly limited the usage quantity of water this moment, but with respect to the quality of mixed solvent, be preferably more than the 2 quality %, more preferably more than the 5 quality %, is preferably below the 70 quality %, more preferably below the 50 quality %.Though solvent is the homogeneous state preferably, also can use non-homogeneous state.

Liquid phase oxidation reaction can adopt any form of continous way, batch type, if consider productivity, in industrial preferred continous way.

As the alkene or the α of liquid phase oxidation reaction raw material, the usage quantity of beta-unsaturated aldehyde is preferably more than 0.1 mass parts with respect to 100 mass parts solvents, more preferably more than 0.5 mass parts, is preferably below 20 mass parts, more preferably below 10 mass parts.

The usage quantity of molecularity oxygen is with respect to 1 mole of raw material olefin or 1 mole of raw material α, beta-unsaturated aldehyde, be preferably more than 0.1 mole, more preferably more than 0.3 mole, be preferably especially more than 0.5 mole, be preferably below 30 moles, more preferably below 25 moles, most preferably be below 20 moles.

Usually, catalyzer uses with suspended state in the reaction solution that carries out liquid-phase oxidation, but also can use fixed bed.The usage quantity of catalyzer, with respect to the 100 mass parts solution that exist in the reactor, with the catalyzer that exists in the reactor, be preferably more than 0.1 mass parts, more preferably more than 0.5 mass parts, be preferably especially more than 1 mass parts, be preferably below 30 mass parts, more preferably below 20 mass parts, be preferably especially below 15 mass parts.

Temperature of reaction and reaction pressure are suitably set according to employed solvent and reaction raw materials.Temperature of reaction is preferably more than 30 ℃, more preferably more than 50 ℃, preferably below 200 ℃, more preferably below 150 ℃.In addition, reaction pressure is preferably more than the normal atmosphere (0MPa), more preferably more than the 2MPa, is preferably below the 10MPa, more preferably below the 7MPa.

Embodiment

Below enumerate embodiment and comparative example is described more specifically the present invention, but the present invention is not limited to embodiment." part " in embodiment and the comparative example refers to mass parts.

(analysis of raw material and product)

Using gas-chromatography analyzes raw material and product.In addition, alkene or α, the transformation efficiency of beta-unsaturated aldehyde, the α of generation, the selection rate of beta-unsaturated aldehyde, the α of generation, the selection rate of beta-unsaturated carboxylic acid is as giving a definition:

Alkene or α, the transformation efficiency of beta-unsaturated aldehyde (%)=(B/A) * 100

α, the selection rate of beta-unsaturated aldehyde (%)=(C/B) * 100

α, the selection rate of beta-unsaturated carboxylic acid (%)=(D/B) * 100

Here A refers to the alkene or the α of supply, and the mole number of beta-unsaturated aldehyde, B are alkene or the α that has reacted, the mole number of beta-unsaturated aldehyde, the α of C for generating, the mole number of beta-unsaturated aldehyde, the α of D for generating, the mole number of beta-unsaturated carboxylic acid.In addition, for α, the oxidizing reaction of beta-unsaturated aldehyde, C/B=0.

Following embodiment and comparative example are the reactions that is prepared methacrylic acid by iso-butylene, this moment, A was the mole number of the iso-butylene of supply, B is the mole number of the iso-butylene that reacted, and C is the mole number of the Methylacrylaldehyde that generates, and D is the mole number of the methacrylic acid that generates.

Embodiment 1

Preparation of catalysts

With 1.1 parts of acid chlorides in the acetic acid aqueous solution of 60 part of 85 quality % after 80 ℃ of heating for dissolving, with it with 5.0 parts of active carbon powder (specific surface area 840m ²/ g) to put into internal volume together be that the autoclave of 150ml is airtight.The speed of changeing with per minute 500 begins to stir, and imports nitrogen to 0.8MPa, three times repeatedly, will use nitrogen replacement in the system.Import propylene then, make pressure rise to 0.6MPa, be warming up to 70 ℃ and kept 1 hour afterwards from normal pressure.

After being cooled to room temperature, remove the system internal pressure, open autoclave.Suction filtration under nitrogen gas stream, the filtering separation black powder is cleaned with the aqueous acetone solution of 75 quality % again, obtains black powder.At this moment, in filtrate, add a small amount of hydrazine monohydrate, confirm not have separating out of palladium.

With the black powder dry night under 100 ℃ of nitrogen gas stream that obtains, obtain carrying palladium metal catalyst.The loading of the palladium in this catalyzer is 10 quality %.

Reaction evaluating

At the internal volume that gas introduction port is installed is to add 100 parts of 75 quality % aqueous acetone solutions as reaction solvent in the autoclave (to call reactor in the following text) of 330ml, 5.5 part above-mentioned catalyzer, and be that the p methoxy phenol of 200ppm is as free radical scavenger with respect to reaction soln.Add 3 parts of trifluoroacetic acids as compound (A) (pKa=0.30) then, behind the closed reaction vessel, import 6.5 parts of liquefaction iso-butylenes again, the speed of changeing with per minute 1000 begins to stir.

Begin afterwards to heat up, when reaching 90 ℃, import nitrogen to 2.4MPa, again with air pressurized to 4.8MPa.Along with the carrying out of reaction, can be observed reacting kettle inner pressure and reduce, but whenever interior drops during 0.1MPa, supplemental oxygen to interior pressure reaches 4.8MPa.Amount to like this and used the oxygen (is 1.04 moles with respect to 1 mole of iso-butylene) that is equivalent to 1.7MPa.Under this state, stir 50 minutes (reaction times).In addition, this reaction times is to be adjusted to make the liquefaction conversion for isobutene reach time about 50%.

After being cooled to about 10 ℃ with ice-water bath, pressure relief also reclaims all gas.From reaction solution, take out a part after opening system, with membrane filter (aperture: 0.5 μ m) remove catalyzer fully.Reaction solution that reclaims and gas come quantitatively with gas-chromatography.

According to the ICP luminescence analysis result of reaction solvent, confirm not have the stripping of palladium.Evaluation result is as shown in table 1.

Embodiment 2

In reaction evaluating, add 3 parts of Mono Chloro Acetic Acids (pKa=2.68) and replace 3 parts of trifluoroacetic acids as compound (A), in 60 minutes reaction times, all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 1.04 moles with respect to 1 mole of iso-butylene) that is equivalent to 1.7MPa in the reaction.Evaluation result is as shown in table 1.

Embodiment 3

In reaction evaluating, add 3 parts of formic acid (pKa=3.55) and replace 3 parts of trifluoroacetic acids as compound (A), in 60 minutes reaction times, all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 0.92 mole with respect to 1 mole of iso-butylene) that is equivalent to 1.5MPa in the reaction.Evaluation result is as shown in table 1.

Embodiment 4

In reaction evaluating, reduce reaction solvent 75 quality % aqueous acetone solutions to 60 part, add 40 parts of acetate (pKa=4.56) as carboxylic acid cpd (B), the reaction times is 50 minutes, all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 1.04 moles with respect to 1 mole of iso-butylene) that is equivalent to 1.7MPa in the reaction.Evaluation result is as shown in table 1.

Embodiment 5

In reaction evaluating, reduce as 75 quality % aqueous acetone solutions to 80 of reaction solvent part, add 20 parts of acetate (pKa=4.56) as carboxylic acid cpd (B), the reaction times is 45 minutes, all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 0.98 mole with respect to 1 mole of iso-butylene) that is equivalent to 1.6MPa in the reaction.Evaluation result is as shown in table 1.

Comparative example 1

In reaction evaluating, do not add trifluoroacetic acid as compound (A), the reaction times is 80 minutes, all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 0.98 mole with respect to 1 mole of iso-butylene) that is equivalent to 1.6MPa in the reaction.Evaluation result is as shown in table 1.

Comparative example 2

In reaction evaluating, add 3 parts of acetate (pKa=4.56) and be used as carboxylic acid cpd (B) and replace 3 parts of trifluoroacetic acids as compound (A), the reaction times is 65 minutes, all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 1.04 moles with respect to 1 mole of iso-butylene) that is equivalent to 1.7MPa in the reaction.Evaluation result is as shown in table 1.

Comparative example 3

In reaction evaluating, minimizing adds 40 parts of acetate (pKa=4.56) as carboxylic acid cpd (B), and does not add the trifluoroacetic acid as compound (A) as 75 quality % aqueous acetone solutions to 60 of reaction solvent part, reaction times is 70 minutes, and all the other operations are all the same with embodiment 1.In addition, used the oxygen (is 1.04 moles with respect to 1 mole of iso-butylene) that is equivalent to 1.7MPa in the reaction.Evaluation result is as shown in table 1.

Table 1

	Compound (A) concentration	Carboxylic acid cpd (B) concentration	Reaction times (minute)	Isobutene conversion (%)	Methacrylaldehyde selection rate (%)	Methacrylic acid selection rate (%)
							Embodiment 1	Trifluoroacetic acid 2.9 quality %	-	50	52.7	44.7	25.5
Embodiment 2	Mono Chloro Acetic Acid 2.9 quality %	-	60	54.8	43.4	23.0
							Embodiment 3	Formic acid 2.9 quality %	-	60	48.7	46.4	20.8
Embodiment 4	Trifluoroacetic acid 2.9 quality %	Acetate 38.8 quality %	50	53.6	40.2	30.7
							Embodiment 5	Trifluoroacetic acid 2.9 quality %	Acetate 19.4 quality %	45	51.4	35.8	33.5
Comparative example 1	-	-	80	57.7	35.0	20.1
							Comparative example 2	-	Acetate 2.9 quality %	65	59.3	37.4	19.7
Comparative example 3	-	Acetate 38.8 quality %	70	52.5	30.7	18.8

As mentioned above, the method according to this invention, selection rate that can be higher is made α, beta-unsaturated carboxylic acid.

Claims (3)

1. α, the manufacture method of beta-unsaturated carboxylic acid is to use the catalyzer that contains precious metal by alkene or α, beta-unsaturated aldehyde is made α in liquid phase, the method of beta-unsaturated carboxylic acid is characterized in that, acid dissociation exponent (pKa) is present in the above-mentioned liquid phase less than 4 compound (A).

2. the described α of claim 1, the manufacture method of beta-unsaturated carboxylic acid, it is characterized in that, compound (B) is present in the above-mentioned liquid phase with compound (A), described compound (B) be acid dissociation exponent (pKa) more than or equal to 4 and carbonatoms be 2～6 carboxylic acid cpd.

3. claim 1 or 2 described α, the manufacture method of beta-unsaturated carboxylic acid is characterized in that, the above-mentioned catalyzer that contains precious metal contains palladium.