Method for producing N-substituted (meth)acrylamides

Abstract

To provide a manufacturing method of a N-substituted (meth)acryl amide having an organic acid and etc. derived from a biomass or an organic acid and etc. derived from a natural material as a starting material.SOLUTION: A manufacturing method of N-substituted (meth)acryl amide characterized in that by using at least one or more kinds of organic acids selected from the group consisting of lactic acid, lactide, 3-hydroxypropionic acid, a lactic acid oligomer, poly (lactic acid) derived from biomass, or 2-hydroxy isobutyric acid, 3-hydroxyisobutyric acid, hydroxy isobutyric acid oligomer and polyhydroxy isobutyric acid derived from a natural material or its derivative and an amine compound as a raw material, and including the following steps (A) and (B). (A) A step of dehydration condensating or a ring-opening reacting between an organic acid or its derivative and an amine compound between molecules to obtain an amide compound; (B) a step of dehydrating the amide compound obtained in the (A) in a molecule to obtain N-substituted (meth)acryl amide.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a process for the preparation of N-substituted (meth)acrylamides from bio-based starting materials. [Background technology]

[0002] N-substituted (meth)acrylamides can be homopolymerized or copolymerized with other polymerizable monomers by various polymerization methods, and are therefore used in an extremely diverse range of fields, including paints, pressure sensitive adhesives, adhesives, various coating agents, papermaking chemicals such as paper strength agents, polymer flocculants used in the treatment of industrial and domestic wastewater, polymer modifiers, dispersants, thickeners, synthetic raw materials for contact lenses and biogels, reactive diluents for UV curing resins, etc. Industrial production methods for N-substituted (meth)acrylamides have been actively studied and reported in the past.

[0003] N-substituted (meth)acrylamides are usually industrially produced from starting materials such as (meth)acrylamide (Patent Document 1), (meth)acrylic acid esters (Patent Document 2), (meth)acrylonitrile (Patent Document 3), and (meth)acrylic acid (Patent Document 4). However, these methods require the use of strong bases or strong acid catalysts, harsh conditions such as high temperature and high pressure, and many reaction steps and complicated operations such as protection, deprotection, and neutralization of unsaturated bonds. Furthermore, toxic catalysts may be used and toxic by-products may be generated, and measures must be taken to separate, recover, and remove these toxic substances, resulting in excessive energy consumption and expensive capital investment. None of these methods are safe and simple and suitable for industrial production.

[0004] In addition, all of the above starting materials are made from petroleum, and in recent years, the depletion of petroleum resources and environmental pollution have become problems, and bio-based production methods using non-petroleum resources have attracted attention. For example, Patent Document 5 proposes a technology for synthesizing acrylic acid and its derivatives by treating lactic acid and its derivatives as raw materials with high-temperature, high-pressure water in the presence of a metal catalyst such as copper. However, this method also requires that the reaction vessel be heat-resistant and pressure-resistant, and since dehydration is performed in high-temperature, high-pressure water, the reaction yield is low, and it is extremely difficult to separate and purify acrylic acid and its derivatives from the aqueous medium, and there is a problem that high-purity products cannot be produced in high yields.

[0005] As described above, a safe and simple industrial production method for N-substituted (meth)acrylamide with high purity and high yield, particularly a process using a bio-based organic acid as a raw material in which only water is produced as a by-product from the viewpoint of green sustainable chemistry, has not yet been established. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 58-18346 [Patent Document 2] JP 2012-97005 A [Patent Document 3] JP 2000-264865 A [Patent Document 4] JP 2012-46431 A [Patent Document 5] JP 2017-14144 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention provides a method for producing N-substituted (meth)acrylamides from bio-based starting materials. In the entire production process of the present invention, only water is produced as a by-product, and various N-substituted (meth)acrylamides can be produced safely and easily with high purity and high yield. [Means for solving the problem]

[0008] The present inventors have conducted intensive research to solve these problems, and as a result have discovered that one or more organic acids or derivatives thereof (cyclic dimers, oligomers and polymers of organic acids) selected from the group consisting of lactic acid, lactide, 3-hydroxypropionic acid, lactic acid oligomers, and polylactic acid derived from biomass, or 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid, hydroxyisobutyric acid oligomers, and polyhydroxyisobutyric acid derived from natural materials, and amines or amine salts are used as raw materials, and an amide compound is obtained as an intermediate by performing an intermolecular dehydration condensation or ring-opening reaction, and then the obtained amide compound is dehydrated intramolecularly to obtain the target compound, N-substituted (meth)acrylamide, thereby completing the present invention.

[0009] That is, the present invention provides: (1) A method for producing an N-substituted (meth)acrylamide, comprising using as raw materials one or more organic acids or derivatives thereof selected from the group consisting of lactic acid, lactide, 3-hydroxypropionic acid, lactic acid oligomers, and polylactic acid derived from biomass, or 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid, hydroxyisobutyric acid oligomers, and polyhydroxyisobutyric acid derived from natural materials, and amines or amine salts, and comprising the following steps (A) and (B): (A) A step of subjecting an organic acid or a derivative thereof to an intermolecular dehydration condensation or ring-opening reaction with an amine or an amine salt to obtain an amide compound. (B) A step of intramolecularly dehydrating the amide compound obtained in (A) to obtain an N-substituted (meth)acrylamide. (2) The method for producing an N-substituted (meth)acrylamide according to (1) above, wherein the amine is a primary amine or a secondary amine represented by the general formula [1]. [ka] (In the formula, R1 and R2 each represent a hydrogen atom (excluding the case where R1 and R2 are both hydrogen atoms), a linear alkyl group or hydroxyalkylene group having 1 to 36 carbon atoms, an alkenyl group or alkyl ether group having 2 to 36 carbon atoms, a branched alkyl group or alicyclic hydrocarbon having 3 to 36 carbon atoms, or an aromatic hydrocarbon having 6 to 36 carbon atoms, and R1 and R2 may combine with the nitrogen atom carrying them to form a saturated 5- to 7-membered ring containing an oxygen atom.) (3) The method for producing N-substituted (meth)acrylamides according to (1) or (2), wherein the amine salt is a salt produced by neutralizing a primary amine or a secondary amine with an acid. (4) The method for producing N-substituted (meth)acrylamide according to (3) above, wherein the acid is hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, formic acid, acetic acid, oxalic acid, adipic acid, glutaric acid, salicylic acid, succinic acid, malonic acid, or p-toluenesulfonic acid. (5) The method for producing N-substituted (meth)acrylamide according to (1) above, wherein the reaction in step (A) is carried out in the presence of a Lewis acid as a catalyst. (6) The method for producing an N-substituted (meth)acrylamide according to (5) above, wherein the Lewis acid is a boron compound. (7) The method for producing N-substituted (meth)acrylamide according to (5) above, wherein the Lewis acid is an organic boron compound. (8) The method for producing N-substituted (meth)acrylamides according to (7) above, wherein the organoboron compound is a boronic acid or a boronic acid derivative. (9) The method for producing N-substituted (meth)acrylamide according to (5) above, wherein the reaction in step (A) further uses a tertiary amine compound as a promoter. (10) The method for producing N-substituted (meth)acrylamide according to (1) above, wherein the reaction in step (B) is carried out in the presence of an inorganic porous catalyst. (11) The method for producing N-substituted (meth)acrylamide according to (10) above, wherein the inorganic porous catalyst contains 30 mol % or more of silica. (12) The method for producing N-substituted (meth)acrylamide according to (10) or (11), wherein the inorganic porous catalyst is one or more selected from the group consisting of silica gel, mesoporous silica, silica alumina, zeolite, aluminosilicate, silica sand, kaolin, and aluminum silicate. (13) The method for producing N-substituted (meth)acrylamides according to any one of (1) to (12) above, characterized in that the N-substituted (meth)acrylamides are N-monosubstituted (meth)acrylamides and N,N-disubstituted (meth)acrylamides represented by the general formula [2]: [ka] (In the formula, R1 and R2 each represent a hydrogen atom (excluding the case where R1 and R2 are both hydrogen atoms), a linear alkyl group or a hydroxyalkylene group having 1 to 36 carbon atoms, an alkenyl group or an alkyl ether group having 2 to 36 carbon atoms, a branched alkyl group or an alicyclic hydrocarbon having 3 to 36 carbon atoms, or an aromatic hydrocarbon having 6 to 36 carbon atoms. R1 and R2 may combine with the nitrogen atom carrying them to form a saturated 5- to 7-membered ring containing an oxygen atom. R3 represents a hydrogen atom or a methyl group.) This provides: Effect of the Invention

[0010] According to the method of the present invention, N-substituted (meth)acrylamides can be safely and simply produced in high yield from organic acids or derivatives thereof derived from biomass or organic acids derived from natural materials (hereinafter referred to as organic acid compounds, etc.). Moreover, the method of the present invention has a small number of reaction steps, produces only water as a by-product, has a low environmental impact, is safe and simple, and can obtain high-purity products in high yield from general-purpose N-substituted (meth)acrylamides to special products such as (meth)acrylamides having bulky cyclic substituents and long-chain alkyl (meth)acrylamides.

[0011] In the production method of the present invention, the catalytic mechanism of a Lewis acid in the dehydration condensation reaction of an organic acid compound, etc. and an amine or an amine salt (hereinafter referred to as an amine compound, etc.) is not necessarily clear. However, the inventors speculate that since the amine compound, etc. is a Lewis base, it is likely to be coordinated to a vacant coordination site of a metal of the Lewis acid or to be coordinated by substituting an existing ligand of the metal, thereby activating the amine compound, etc., and allowing the reaction to proceed smoothly even under mild conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present invention provides a method for efficiently and industrially producing N-monosubstituted (meth)acrylamide and N,N-disubstituted (meth)acrylamide as N-substituted (meth)acrylamides, which comprises the following two steps (A) and (B):

[0013] Step (A) is carried out by reacting an organic acid compound or the like with an amine compound or the like in the presence of a Lewis acid catalyst, and hydroxypropionamide or hydroxyisobutyric acid amide can be obtained as an intermediate in good yield without complicated operations. In addition, the ring-opening reaction of lactide with an amine compound or the like proceeds sufficiently even without a catalyst, but in the case of a bulky amine compound or the like having a branched or cyclic substituent, the steric hindrance is large, so the reaction is promoted by a Lewis acid catalyst, and the reaction can be completed at a low temperature even in a short time, which is preferable.

[0014] In step (B), the intermediate amide compound obtained in step (A) is dehydrated intramolecularly in the presence of an inorganic porous catalyst to produce the target compound, N-substituted (meth)acrylamide. Gas-phase dehydration or liquid-phase dehydration can be selected depending on the structures of the intermediate and the target compound. In addition, since the resulting N-substituted (meth)acrylamide is easily polymerized, it is preferable to carry out the dehydration in the presence of a radical polymerization inhibitor.

[0015] Each step of the present invention will be described in detail below. (A) Process The organic acid compound used in the step (A) is one or more organic acids or derivatives thereof selected from the group consisting of lactic acid, lactide, 3-hydroxypropionic acid, lactic acid oligomer, and polylactic acid derived from biomass, or 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid, hydroxyisobutyric acid oligomer, and polyhydroxyisobutyric acid derived from natural materials. Lactic acid is produced by fermentation, and lactic acid oligomers and polylactic acid are obtained by thermal dehydration polymerization of lactic acid. Lactide is a cyclic compound having two ester bonds formed by dehydration condensation of the hydroxyl group and the carboxyl group of two molecules of hydroxycarboxylic acid in the molecule, and lactide (lactide lactide) from two molecules of lactic acid is preferable from the viewpoint of originating from biomass. Lactide lactide is produced by dehydration condensation of lactic acid, and low molecular weight polylactic acid (lactic acid oligomer) obtained by dehydration condensation polymerization of lactic acid can be once decomposed by heating under reduced pressure to synthesize lactide, which is a cyclic dimer. In addition, 2-hydroxyisobutyric acid can be synthesized from fermentatively produced acetone, fermentatively produced alkyl esters of pyruvate, and fermentatively produced lactate. 3-hydroxypropionic acid can be produced by fermenting sugar using microorganisms, and can also be produced from glycerin in the presence of a catalyst via 3-hydroxypropionaldehyde.

[0016] The amine compounds, etc. used in step (A) are amines or amine salts. Amines are primary or secondary amines represented by the general formula [3], and amine salts are salts formed by neutralizing these primary or secondary amines with acids. In the reaction of step (A), amines and amine salts can be used in the same reaction, but the selection can be made by comprehensively considering the reaction conditions, ease of handling of the amines and amine salts, and the possibility of separating them from the target product. Amines can react directly with organic acid compounds, etc., and amine salts are liberated into amines using tertiary amines or other basic substances and then reacted with organic acid compounds, etc. [ka] (In the formula, R1 and R2 each represent a hydrogen atom (excluding the case where R1 and R2 are both hydrogen atoms), a linear alkyl group or hydroxyalkylene group having 1 to 36 carbon atoms, an alkenyl group or alkyl ether group having 2 to 36 carbon atoms, a branched alkyl group or alicyclic hydrocarbon having 3 to 36 carbon atoms, or an aromatic hydrocarbon having 6 to 36 carbon atoms, and R1 and R2 may combine with the nitrogen atom carrying them to form a saturated 5- to 7-membered ring containing an oxygen atom.)

[0017] The amines used in step (A) are linear or branched, saturated or unsaturated aliphatic primary amines and secondary amines, primary alkanolamines and secondary alkanolamines having a hydroxyl group, primary alkyl ether amines and secondary alkanolamines having an ether group, the above primary amines and secondary amines having an alicyclic hydrocarbon, the above primary amines and secondary amines having an aromatic hydrocarbon, and morpholine. Specifically, (di)methylamine, (di)ethylamine, (di)propylamine, (di)isopropylamine, (di)butylamine, (di)isobutylamine, (di)pentylamine, (di)hexylamine, (di)heptylamine, (di)octylamine, (di)nonylamine, (di)decylamine, (di)oleylamine, distearylamine, methylethylamine, methyl(iso)propylamine, methyl(iso)butylamine, methyl(iso)hexylamine, ethyl(iso)propylamine, ethyl(iso)butylamine, ethyl(iso)hexylamine, propylisopropylamine, propylbutylamine, propylhexylamine, Examples of such amines include ethanolamine, isopropylbutylamine, isopropylisobutylamine, isopropylhexylamine, butylisobutylamine, butylhexylamine, oleylstearylamine, monoethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, diethanolamine, propanolamine; isopropanolamine, butanolamine, pentanolamine, hexanolamine, (di)cyclopropylamine, (di)cyclobutylamine, (di)cyclopentylamine, (di)cyclohexylamine, (di)phenylamine, (di)benzylamine, and morpholine.

[0018] The amine salts used in step (A) are salts formed by neutralization of the primary or secondary amine with an acid. The acids used in the neutralization reaction are hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, formic acid, acetic acid, oxalic acid, adipic acid, glutaric acid, salicylic acid, succinic acid, malonic acid, and p-toluenesulfonic acid. Taking into consideration safety, ease of handling, cost, and the like, hydrochloric acid, sulfuric acid, acetic acid, and salicylic acid are preferred.

[0019] The catalyst used in step (A) is a Lewis acid, and is not particularly limited as long as it is composed of a central metal and an electron-withdrawing group bonded to the metal and can accept an unshared electron pair. Metal elements include boron, aluminum, scandium, titanium, iron, zinc, arsenic, zirconium, niobium, cadmium, indium, tin, antimony, hafnium, mercury, lanthanoids, etc., and electron-withdrawing groups include halogen groups, trifluoromethyl groups, trifluoromethanesulfonyl (triflate), sulfonyl groups, methanesulfonyl groups, trifluoroacetyl groups, nitro groups, etc., and Lewis acids are formed by combining these metals with electron-withdrawing groups. For example, metal halides include boron trifluoride, aluminum chloride and titanium chloride (titanium trichloride), and metal trifluoromethanesulfonates (triflates) include lanthanoid triflates, ytterbium triflates, and triflates of iron (II), copper (II), zinc (II), cadmium (II), lead (II), etc. These Lewis acids may be used alone or in combination of two or more.

[0020] The Lewis acid catalyst used in step (A) is preferably a boron compound. The boron compound is a compound having boron, and specifically includes acids such as boric acid and hydrofluoroboric acid, salts such as sodium tetraborate, sodium perborate, and potassium fluoroborate, oxides such as diboron trioxide, halides such as boron trichloride and boron trifluoride, and organic boron compounds such as triethylborane, enolborane, alkynylborane, boronic acid, boronate ester, and borazine derivatives. Boron compounds act as catalysts as Lewis acids useful in synthesizing amides from carboxylic acids and amines, and although the mechanism has not been elucidated, the inventors believe that this is due to the fact that boron is a semimetal having intermediate properties between metal elements and nonmetal elements. Among them, trinuclear boron compounds such as boric acid, sodium tetraborate, diboron trioxide, and organic boron compounds exhibit appropriate strength as Lewis acids and are more preferable.

[0021] It is particularly preferred that the Lewis acid catalyst used in step (A) is an organic boron compound. Depending on the type and number of substituents bonded to the boron atom, examples of the organic boron compound include organic borane compounds such as trialkylborane, dialkoxyalkynylborane, and triphenylborane, aliphatic and aromatic boronic acids, aliphatic and aromatic borinic acids, and ester derivatives thereof. Among these, boronic acids are the most preferred because they have a structure in which the hydroxyl group of boric acid is replaced with an alkyl group or an aryl group, and they act as Lewis acids while easily forming reversible covalent bond complexes with the organic acid compounds and the like as raw materials, and are more likely to approach and react with amine compounds and the like.

[0022] Representative compounds of the boronic acid are alkylboronic acid, alkenylboronic acid, and arylboronic acid (aromatic boronic acid). Specifically, methylboronic acid, ethylboronic acid, cyclopropylboronic acid, isopropylboronic acid, n-propylboronic acid, cyclobutylboronic acid, n-butylboronic acid, t-butylboronic acid, 4-bromobutylboronic acid, 2-methylpropylboronic acid, cyclopentylboronic acid, 5-bromopentylboronic acid, cyclohexylboronic acid, 6-bromohexylboronic acid, 2,6-dichlorobenzylboronic acid, cyclohexylmethylboronic acid, phenethylboronic acid, trans-2-chloromethylvinylboronic acid, cis-1-propen-1-ylboronic acid, trans-1-propen-1-ylboronic acid, 2,2-Dimethylethyleneboronic acid, but-3-enylboronic acid, cyclopenten-1-ylboronic acid, 1-penten-1-ylboronic acid, 3-methyl-2-buten-2-ylboronic acid, 4-pentenylboronic acid, vinylboronic anhydride pyridine complex, 1-cyclohexen-1-ylboronic acid, 4-methyl-1-pentenylboronic acid, 5-hexenylboronic acid, 1-cyclohepten-1-ylboronic acid, 2-(cyclopentyl)ethenyl-1-boronic acid, 4-methyl-1-cyclohexen-1-ylboronic acid, 4-ethylcyclohexen-1-ylboronic acid, trans-1-heptenylboronic acid alkenylboronic acid, trans-1-octen-1-ylboronic acid, phenylboronic acid, 4-ethylphenylboronic acid, 2-naphthylboronic acid, naphthalene-1-boronic Acid, fluorene-2-boronic acid, 9-anthraceneboronic acid, 9-phenanthracenylboronic acid, pyrene-1-boronic acid, trans-2-(4-chlorophenyl)vinylboronic acid, trans-2-(4-chlorophenyl)vinylboronic acid, trans-2-(3-fluorophenyl)vinylboronic acid, trans-2-(4-fluorophenyl)vinylboronic acid, 1-phenylvinylboronic acid, trans-2-phenylvinylboronic acid, trans-2-(4-(trifluoromethyl)phenyl)vinylboronic acid, trans-2-(4-methylphenyl)vinylboronic acid, trans-3-phenyl-1-propen-1-ylboronic acid, trans-2-(4-methoxyphenyl)vinylboronic acid, 4-t-butylcyclohexen-1-ylboronic acid, etc.,

[0023] In the step (A), the amine compound, etc. can be used in a stoichiometric amount relative to the organic acid compound, etc., or it is preferable to use it in excess of that amount since the reaction is promoted. In general, the amine compound, etc. is used in a range of 1 to 30 times the molar amount relative to the number (molar amount) of carboxyl groups in the organic acid compound, etc. That is, lactic acid, 3-hydroxypropionic acid, 2-hydroxyisobutyric acid, 3-hydroxyisobutyric acid, etc. correspond to monofunctional organic acid compounds, and the amine compound, etc. is used in a range of 1 to 30 times the molar amount of these organic acid compounds, preferably in a range of 1.05 to 20 times the molar amount, and more preferably in a range of 1.1 to 10 times the molar amount. Lactide corresponds to a bifunctional organic acid compound, and the amine compound, etc. is used in a range of 2 to 50 times the molar amount of lactide, preferably in a range of 2.05 to 40 times the molar amount, and more preferably in a range of 2.1 to 30 times the molar amount. Lactic acid oligomer, polylactic acid, hydroxyisobutyric acid oligomer, and polyhydroxyisobutyric acid are polyfunctional organic acid compounds, and the amine compounds and the like are used in an amount of 1 to 10 times by mole, preferably 1.05 to 8 times by mole, and more preferably 1.1 to 5 times by mole, based on the number of carboxyl groups of these organic acid compounds.

[0024] In the step (A), the reaction temperature and reaction time can be appropriately selected depending on the type of organic acid compound, amine compound, etc., the molar ratio of the charged materials, the type of catalyst, and the amount used. Usually, the reaction temperature is about 20 to 160°C, and the reaction time is in the range of 0.5 to 48 hours. In addition, the reaction temperature is preferably about 20 to 100°C, and the reaction time is in the range of 1 to 36 hours. If the reaction temperature is less than 20°C or the reaction time is less than 0.5 hours, the reaction rate may be significantly reduced, while if the reaction temperature exceeds 160°C, the organic acid compound, amine compound, etc. are easily desorbed outside the reaction system, and side reactions occur frequently, which is not preferable. In addition, if the reaction time exceeds 48 hours, there will be disadvantages in productivity and cost.

[0025] In step (A), the amount of the Lewis acid catalyst used can be appropriately adjusted depending on the type and properties (liquid or solid at reaction temperature) and solubility of the organic acid compound etc. and the amine compound etc., the reaction temperature, the reaction time, and the presence or absence of a solvent, but the amount of the Lewis acid catalyst is usually in the range of 0.1 to 200 mol%, preferably in the range of 0.5 to 100 mol%, and particularly preferably in the range of 1 to 50 mol%, based on the number (molar number) of carboxyl groups in the organic acid compound etc. If the amount of the catalyst used is less than 0.1 mol%, the reaction between the organic acid compound etc. and the amine compound etc. may not be completed within 48 hours depending on the type of catalyst, and if the amount of the catalyst used exceeds 200 mol%, separation and purification of the target product after the reaction may take time and effort, which is not preferable.

[0026] In step (A), a tertiary amine compound can be further used as a promoter. The tertiary amine compound is a compound having three hydrocarbon groups bonded to a nitrogen atom. The hydrocarbon groups can be selected from the group consisting of aliphatic hydrocarbon groups having 1 to 20 carbon atoms, alicyclic hydrocarbon groups having 3 to 20 carbon atoms, and aromatic hydrocarbon groups having 6 to 20 carbon atoms, and may be the same or different, as long as they are compounds having three nitrogen-carbon bonds. Examples of the aliphatic hydrocarbon groups having 1 to 20 carbon atoms include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, s-butyl groups, t-butyl groups, various hexyl groups ("various" includes linear and all branched groups, and the same applies below), various octyl groups, various decyl groups, various dodecyl groups, various tetradecyl groups, various hexadecyl groups, various nonadecyl groups, and various eicosyl groups. Among these, aliphatic hydrocarbon groups having 2 to 10 carbon atoms are preferred, aliphatic hydrocarbon groups having 2 to 6 carbon atoms are more preferred, and from the viewpoint of the effect of acting as a co-catalyst for tertiary amines, branched aliphatic hydrocarbon groups are particularly preferred, and isopropyl, isobutyl, and isohexyl groups are more preferred. The aliphatic hydrocarbon groups may be substituted with aromatic hydrocarbon groups having 6 to 10 carbon atoms, such as phenyl and naphthyl groups. Examples of alicyclic hydrocarbon groups having 3 to 20 carbon atoms include cyclopropyl, cyclopentyl, cyclooctyl, and norbornyl groups. Among these, alicyclic hydrocarbon groups having 3 to 10 carbon atoms are preferred, and alicyclic hydrocarbon groups having 3 to 6 carbon atoms are more preferred. Examples of aromatic hydrocarbon groups having 6 to 20 carbon atoms include phenyl, tolyl, naphthyl, and anthryl groups. Among these, aromatic hydrocarbon groups having 6 to 10 carbon atoms are preferred. From the viewpoint of the action and effect of the co-catalyst, a tertiary amine compound having a bulky structure is preferred, and a tertiary amine compound having one or more branched or cyclic aliphatic hydrocarbon groups is particularly preferred. These tertiary amine compounds may be used alone or in combination of two or more.

[0027] In the step (A), the amount of the tertiary amine compound used as a co-catalyst can be appropriately adjusted depending on the type and properties of the organic acid compound and the amine compound of the Lewis acid catalyst, the reaction temperature, the reaction time, and the presence or absence of a solvent, but is usually in the range of 0 to 1000 mol%, preferably in the range of 0.5 to 150 mol%, and particularly preferably in the range of 1 to 100 mol% relative to the Lewis acid catalyst. The function of the co-catalyst is not clear, but the inventors believe that it has the effect of suppressing the formation of a neutralized salt between the organic acid compound and the amine compound, and as a result, the amidation reaction proceeds quickly. When the organic acid compound is lactic acid, 3-hydroxypropionic acid, 2-hydroxyisobutyric acid, or 3-hydroxyisobutyric acid, and the amine compound is a primary amine or a secondary amine, the amount of the co-catalyst used is preferably 100 mol% or more relative to the Lewis acid catalyst. In addition, when the organic acid compound is lactide, lactic acid oligomer, polylactic acid, hydroxyisobutyric acid oligomer, or polyhydroxyisobutyric acid, or when the amine compound is an amine salt, a neutral salt of the carboxylic acid group and the amine group is not easily formed, and therefore a tertiary amine compound as a promoter is not required. If the amount of the promoter used exceeds 1000 mol%, it may take time and effort to separate and purify the target product after the reaction, which is not preferable.

[0028] The reaction in step (A) can be carried out under normal pressure, under pressure using a pressure-resistant reaction apparatus, or under reduced pressure using a device capable of reducing pressure such as a vacuum pump. When the organic acid compound or amine compound has a low boiling point, the raw material can be enclosed in a device capable of being pressurized, reacted under pressure or heating conditions, and then the by-product water can be removed by heating under normal pressure or reduced pressure. When the organic acid compound is an oligomer or polymer, it can be hydrolyzed to a monomer under pressure or heating conditions and then subjected to an amidation reaction with the amine compound or the like while being hydrolyzed. In the case of lactide, the ring-opening reaction and the amidation reaction proceed simultaneously, so that the reaction can be easily completed even in a low-cost normal pressure reaction. When a monofunctional organic acid compound such as lactic acid, 3-hydroxypropionic acid, 2-hydroxyisobutyric acid, or 3-hydroxyisobutyric acid is reacted with an amine compound having a boiling point of 100°C or higher, the amidation can be carried out while removing the by-product water under reduced pressure. In addition, the pressure in the reaction system can be changed while analyzing the conversion rate of the raw material and the yield of the target product.

[0029] The reaction in step (A) can proceed with sufficient selectivity and yield even without a solvent. A solvent may be used as necessary. When organic acid compounds and amine compounds are liquid at a given reaction temperature, particularly when amine compounds are used in excess, they function as a raw material for the reaction and also as a solvent for the reaction. When the amine compounds are amine salts, it is necessary to use an equivalent or greater amount of inorganic or organic alkali relative to the amine salts in order to liberate the amine compounds from the amine salts. When the amine salts are solid at the reaction temperature, it is preferable to use a solvent to dissolve them. The reaction solvent is not particularly limited, and a general solvent can be used as long as it does not cause a side reaction with the starting materials, products, and Lewis acid catalyst of the reaction. Examples of the reaction solvent include hydrophobic solvents such as toluene and xylene, and hydrophilic solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-butylpyrrolidone. When a solvent is used, the amount of the solvent used is usually in the range of 20 to 1000% by weight, preferably in the range of 50 to 500% by weight, and particularly preferably in the range of 100 to 300% by weight, based on the total amount of the organic acid compound etc. and the amine compound etc. When the reaction solvent is used for the purpose of dissolving the raw materials or improving the stirring efficiency, if the amount is less than 20% by weight, sufficient effect may not be expected, and if the amount is more than 1000% by weight, it is uneconomical and may cause a decrease in the reaction rate.

[0030] The reaction in step (A) may be a batch or continuous system, and may be a homogeneous or heterogeneous system in the state of the Lewis acid catalyst, and may be a fluidized bed or a fixed bed supply system for the catalyst. In the case of a batch system, for example, the raw materials, such as an organic acid compound, an amine compound, a Lewis acid catalyst, and a solvent, are charged into a reaction vessel, and the atmosphere in the reaction apparatus and the reaction liquid is replaced with an inert gas as necessary, and then the reaction temperature and pressure are adjusted to a predetermined value while maintaining the suspension or dissolution state by stirring, and the reaction is carried out for a predetermined time. In addition, the reaction liquid mixture after the reaction is completed may be separated into solid and liquid by filtration or centrifugation, for example, if the catalyst is present in a solid state, and then recovered, or may be decanted or concentrated without separation, and then reused as it is (step A) or carried over to the next step (step B). On the other hand, if the catalyst after the reaction is dissolved in the reaction liquid, the reaction liquid may be concentrated, and then reused as it is (step A) or carried over to the next step (step B). Furthermore, regardless of the dissolved or dispersed state of the catalyst after the reaction is completed, the reaction liquid can be carried over to the next step (step B) without being concentrated.

[0031] In the reaction of step (A), when the organic acid compound etc. is lactide, lactic acid oligomer, polylactic acid, hydroxyisobutyric acid oligomer, or polyhydroxyisobutyric acid, the order in which the organic acid compound etc., amine compound etc., Lewis acid catalyst, and tertiary amine compound are added to the reaction system is not particularly limited, but when the organic acid compound etc. is lactic acid, 3-hydroxypropionic acid, 2-hydroxyisobutyric acid, or 3-hydroxyisobutyric acid, it is better to charge the organic acid compound etc., Lewis acid catalyst, amine compound etc. in this order into the reaction vessel. In addition, when a tertiary amine compound is used as a co-catalyst, it is preferable to add it before the amine compound etc.

[0032] In the reaction of step (A), when the amine compound or the like is an amine salt, an inorganic or organic alkali is used to liberate the amine from the amine salt and then the amine is reacted with the organic acid compound or the like. In this case, the by-product water can be removed by reducing pressure or heating before the reaction, or may be removed at the same time as the by-product water is removed in the amidation reaction.

[0033] (B) Process In the step (B), the amide compound, which is an intermediate obtained in the step (A), is used in the presence of an inorganic porous catalyst at a predetermined reaction temperature and operating pressure to remove water from the amide compound by liquid-phase or gas-phase pyrolysis (intramolecular dehydration) reaction, thereby producing N-substituted (meth)acrylamide. The reaction solvent, unreacted raw materials, by-products, etc. brought in from the step (A) are distilled and recovered in order of boiling point, and the target N-substituted (meth)acrylamide can be obtained as a distillate component or distillate residue. In addition, depending on the physical properties of the target product, raw materials, by-products, and reaction solvent, the target product can be separated and purified by known methods such as precipitation, washing, extraction, centrifugation, and separation by ion exchange resin, instead of distillation, to obtain the target product. Furthermore, if necessary, the target product obtained can be subjected to known methods such as precision distillation, recrystallization, sublimation, permeation, and adsorption to obtain a high-purity target product. In the reaction of this step, the amide compound obtained in step (A) can be used to carry out a dehydration reaction while contacting it with an inorganic porous catalyst. The reaction proceeds at a sufficient rate even with a crude amide compound, but it is preferable to use a separated and purified amide compound, since it is possible to obtain N-substituted (meth)acrylamide in high yield and high selectivity. The reaction of step (B) is preferably carried out in the presence of a polymerization inhibitor. In addition, a known radical polymerization inhibitor can be used as the polymerization inhibitor.

[0034] The inorganic porous catalyst used in step (B) is an inorganic material having numerous fine pores inside, such as porous glass or porous ceramics, and is divided into microporous materials, mesoporous materials, and macroporous materials depending on the size of the pores. Examples include microporous inorganic materials such as zeolite, mesoporous inorganic materials such as mesoporous silica, and macroporous inorganic materials such as pumice. The reaction in step (B) is adjusted to be carried out in a gas phase or liquid phase depending on the physical properties such as the boiling point and molecular size of the intermediate amide compound and the product N-substituted (meth)acrylamide. When the boiling point is low and the molecular size is small, the amide compound is easily vaporized, and the vaporized molecules can complete the dehydration reaction while passing through the microporous, so a gas phase reaction is preferred. On the other hand, when the boiling point is high and the molecular size is large, the amide compound is difficult to vaporize, and the dehydration reaction is carried out in a liquid state using mesoporous or macroporous, so a liquid phase reaction is preferred.

[0035] The shape of the inorganic porous catalyst used in step (B) is not particularly limited, and may be a powder, fine particles, granules, or a molded product such as a thin film, and may be appropriately selected from shapes suitable for a fluidized bed, a fixed bed, or the like, depending on the reaction method. Specific examples include silica gel, mesoporous silica, silica alumina, zeolite, aluminosilicate, diatomaceous earth, natural sand, silica sand, ceramics, activated clay, acid clay, kaolin, and synthetic aluminum silicate. In addition, the inorganic porous catalyst preferably contains 30 mol% or more of silica (silicon dioxide) (hereinafter referred to as "porous silica"). When the inorganic porous catalyst contains 30 mol% or more of silica, the inorganic porous catalyst has sufficiently high water resistance even at high temperatures, making it optimal as a catalyst for a dehydration reaction. In addition, the dehydration reaction may be performed in a batch or continuous manner. For example, in the case of a batch-type liquid-phase dehydration reaction, the catalyst is preferably in the form of a powder or fine particles in terms of the reaction activity point. In addition, in the form of fine particles, the catalyst can be used because it is easy to handle in the state of a uniformly dispersed dispersion in water or an organic solvent. When used as a dispersion, it can be added to the reaction system, the dispersant is removed by distillation or the like, and then the dehydration reaction can be carried out under predetermined conditions.

[0036] Examples of the porous silica used in step (B) include silica gel, mesoporous silica, silica alumina, zeolite, aluminosilicate, natural sand, quartz sand, ceramics, kaolin, synthetic aluminum silicate, etc. One or more types selected from these porous silicas can be used.

[0037] In the present invention, the porous silica gel is a silica gel having pores, and can be used without being limited by the manufacturing method. The shape of the porous silica gel may be crushed non-spherical silica gel or spherical silica gel, but spherical silica gel is more preferable because it has high strength and is easy to recycle. In addition, the "spherical" in the present invention is not limited to a perfect sphere, but includes a slightly deformed sphere such as an oval sphere, and has an average sphericity of 0.5 or more, and more preferably 0.85 or more. In the spherical silica gel, the average particle size is usually 0.1 to 10,000 μm, and preferably 1 to 5,000 μm. The average pore size is 0.5 to 100 nm, and preferably 2 to 50 nm. The specific surface area is 10 to 10,000 m 2 / g, 30 to 1000m 2 / g is more preferable. Outside these ranges, the content of effective particles and pores may decrease, leading to a decrease in the dehydration reaction rate and the progression of side reactions. The porous silica gel used in the present invention is readily available as a commercially available industrial product, and can also be synthesized or treated by known methods. Examples include Silica Gel 40, Silica Gel 60, Wakosil C-200, Wakosil C-300, etc., which are often used as chromatography supports.

[0038] In the present invention, mesoporous silica is an inorganic substance mainly composed of silicon dioxide having uniform and regular mesopores (pores with a diameter of 2 to 50 nm). Mesoporous silica may be in the form of a powder, fine particles, or a molded product such as a thin film. In addition, spherical fine particles are more preferable in terms of a large specific surface area, high strength, ease of recycling, and easy industrial production. The pore diameter of mesoporous silica is 2 to 50 nm, and preferably 2 to 10 nm. If the pore diameter of mesoporous silica is smaller than 2 nm, the diffusion rate of the molecules of amide compounds and N-substituted (meth)acrylamide is low, and there is a risk of reducing reactivity. On the other hand, if the pore diameter of mesoporous silica is larger than 50 nm, it is difficult to form a transition state between the molecules of amide compounds and N-substituted (meth)acrylamide, and N-substituted (meth)acrylamide cannot be obtained with high selectivity and high yield.

[0039] The specific surface area of ​​mesoporous silica is 10 to 3000 m 2 / g, 50 to 3000m 2 / g is preferable. A particulate catalyst having a specific surface area in this range can be easily produced, and the molecules of the amide compound can efficiently come into contact with the catalyst and act. The specific surface area can be determined, for example, by the BET method, which measures the specific surface area by adsorbing nitrogen gas. The average particle size is 0.2 to 10,000 μm, and preferably 1 to 5,000 μm.

[0040] Representative examples of mesoporous silica include MCM-41, MCM-48, MCM-50, SBA-1, SBA-11, SBA-15, SBA-16, FSM-16, KIT-5, KIT-6, HMS (hexagonal), MSU-F, MSU-H, etc. These mesoporous silicas can be obtained commercially and used, or can be synthesized using known methods.

[0041] There is no particular limitation on the method for synthesizing mesoporous silica, but a known method of calcining a reaction complex of a silica source and a cationic or neutral surfactant as a template can be used. As the type of silica source, colloidal silica, silica gel, silicate such as sodium silicate, and alkoxysilane such as tetramethoxysilane and tetraethoxysilane can be used alone or in combination. As the template, a quaternary ammonium salt having an alkyl group with 8 or more carbon atoms, particularly a cationic surfactant based on halogenated alkyltrimethylammonium and a neutral surfactant based on poly(ethylene glycol-ethylene) block copolymer can be preferably used. In addition, the template remaining in the reaction complex is treated with an acidic solution and then calcined to remove it, thereby synthesizing mesoporous silica.

[0042] The calcination treatment is preferably carried out in the presence of air or oxygen. The calcination temperature is 200 to 800°C, and more preferably 300 to 700°C. If the calcination temperature is less than 200°C, the burning of the template is slow, and it may not be possible to sufficiently remove it. If the calcination temperature is more than 800°C, there is a drawback that the silica constituting the pore walls partially collapses.

[0043] In the present invention, silica-alumina is a composite oxide mainly composed of silica (SiO2) and alumina (Al2O3), and may be crystalline or amorphous. The total content of silica and alumina in silica-alumina is preferably 95% by weight or more, and the content of silica is preferably 30 mol% or more. The silica-alumina catalyst used in the present invention may be a powder, fine particles, or a molded product such as a thin film. In addition, spherical fine particles are more preferred in terms of a large specific surface area, high strength, ease of recycling, and easy industrial production. In spherical particulate silica-alumina, the average particle size is usually 0.2 to 20,000 μm, preferably 1 to 10,000 μm. The average pore size is 1 to 100 nm, preferably 2 to 50 nm. The specific surface area is 10 to 10,000 m 2 / g, 30 to 1000m 2It is more preferable that the average particle size and specific surface area of ​​the catalyst is within this range. This range is advantageous in that it is easy to produce a spherical particle catalyst having an average particle size and specific surface area within this range, the diffusion rate of the amide compound or N-substituted (meth)acrylamide molecules is high, the transition state is easily formed, and the target compound can be obtained with high selectivity and high yield.

[0044] Silica alumina is easily available as a commercially available industrial product, and can also be synthesized or treated by a known method. For example, silica alumina can be produced by drying and firing a silica alumina hydrogel prepared from a silica source such as water glass or silica gel, and an alumina source such as aluminum sulfate, sodium aluminate, or alumina gel by a coprecipitation method, a gel kneading method, a gel deposition method, a cogelation method, an impregnation method, or the like. It can also be produced by an alkoxide method (sol-gel method) in which a mixed solution of tetraethoxysilane and aluminum isopropoxide is hydrolyzed, a chemical vapor deposition method, or the like. The silica alumina produced in this way can be highly purified by thoroughly washing it with water and firing it at about 400 to 700 ° C. for several to several tens of hours. Examples of commercially available products include silica alumina 308 manufactured by Fuji Silysia Chemical Co., Ltd., N633HN, N631HN, N633L, and N631L manufactured by JGC Catalysts and Chemicals Co., Ltd., and Al-MCM-41 and Al-MSU-F manufactured by Sigma-Aldrich Co., Ltd.

[0045] In the present invention, zeolite is a crystalline composite oxide of silicon and aluminum having regular micropores, and may be either a natural product or a synthetic product. In addition, structural types include MFI type, β type, mordenite type (MOR), faujasite type (FAU), ferrierite type (FER), LTL type, LTA type, MWW type, MSE type, Y type FAU, and X type FAU. The SiO2 / Al2O3 molar ratio, which is a component of zeolite, is 1 or more, preferably 2 or more. When the SiO2 / Al2O3 molar ratio is less than 1, the amount of acid sites derived from alumina increases, and side reactions tend to occur. In addition, zeolite may be in the form of powder, granules, or molded body. Spherical fine particles are more preferable in terms of large specific surface area, high strength, easy recycling, and easy industrial production. In spherical particle-type zeolite, the average particle size is usually 1 to 500 μm, and the specific surface area is usually 150 m. 2 / g or more, pore volume is 0.1-2 cm 3 / g. If the specific surface area and pore volume are within these ranges, the activity of the catalyst will not decrease, which is preferable. The zeolite used in the present invention may be a commercially available product, or may be prepared by a known method. Examples of commercially available products include Y-type 320HOA, FER-type 720KOA, MOR-type 640HOA, 690HOA, and MFI-type 890HOA manufactured by Tosoh Corporation.

[0046] In the present invention, an aluminosilicate is a compound having a structure in which some of the silicon atoms in a silicate are replaced with aluminum atoms, and contains metal ions such as sodium, potassium, calcium, etc. in a form that compensates for the positive charge lost by the replacement. Examples of natural minerals include mullite, kaolinite, illite, feldspar, and zeolite.

[0047] In the present invention, aluminum silicate is a type of silicate, and is a general term for a composition in which aluminum oxide, silicon dioxide, water, etc. are combined in various ratios. Examples of natural minerals include imogolite and halloysite, and an example of synthetic aluminum silicate is amorphous Kyoward 700 (manufactured by Kyowa Chemical Industry Co., Ltd.). Examples of natural sand and silica sand include Toyo Silica Sand (manufactured by Toyo Materan Co., Ltd.), and examples of kaolin include wet kaolin, metakaolin, and calcined kaolin.

[0048] In step (B), the amount of inorganic porous catalyst used may be appropriately adjusted depending on the reaction state (liquid phase reaction or gas phase reaction), reaction temperature and operation pressure, the shape of the inorganic porous catalyst, the method used (fluidized bed or fixed bed), etc. Usually, the amount of catalyst used in the liquid phase pyrolysis reaction is 0.1 to 100% by weight based on the raw material amide compound in step (B). In addition, the amount of inorganic porous catalyst used is preferably 1 to 80% by weight, and particularly preferably 2 to 50% by weight. If the amount of inorganic porous catalyst used is less than 0.1% by weight, the rate of pyrolysis reaction may not be fully satisfactory, and if the amount used exceeds 100% by weight, the viscosity of the reaction liquid in the powder catalyst is likely to increase, which is not preferable.

[0049] The reaction in step (B) is preferably carried out in the presence of a radical polymerization inhibitor. Known polymerization inhibitors can be used, including, for example, phenolic compounds such as hydroquinone, methylhydroquinone, tert-butylhydroquinone, 2,6-di-tert-butylparahydroquinone, 2,5-di-tert-butylhydroquinone, 2,4-dimethyl-6-tert-butylphenol, and hydroquinone monomethyl ether, N-isopropyl-N'-phenyl-para-phenylenediamine, N-(1,3-dimethylbutyl)-N'-phenyl-para-phenylenediamine, and N-(1-methylheptyl)-N'-phenyl-para-phenylenediamine. Examples of the polymerization inhibitor include paraphenylenediamines such as N,N'-diphenyl-para-phenylenediamine, N,N'-di-2-naphthyl-para-phenylenediamine, amine compounds such as thiodiphenylamine, piperidine-1-oxyl free radical compounds such as 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and acetamide tetramethylpiperidine-1-oxyl. These polymerization inhibitors may be used alone or in combination. The amount of the polymerization inhibitor added is 1 to 10,000 ppm, preferably 5 to 5,000 ppm, relative to the amide compound.

[0050] The reaction temperature and reaction time in step (B) vary depending on the reaction state, and may be adjusted appropriately. In the case of a liquid phase reaction, the reaction temperature is about 80 to 250°C, and the reaction time is in the range of 1 to 40 hours. Also, the preferred reaction temperature is about 100 to 200°C, and the reaction time is in the range of 1 to 30 hours. If the reaction temperature is less than 80°C or the reaction time is less than 1 hour, the pyrolysis reaction rate drops significantly, while if the reaction temperature exceeds 250°C, polymerization of the product and other side reactions increase, which is not preferred. Also, if the reaction time exceeds 40 hours, productivity drops, costs increase, etc., which is not preferred.

[0051] When the reaction in step (B) is carried out in a gas phase, the amide compound obtained in step (A) is evaporated, and N-substituted (meth)acrylamide can be produced by a pyrolysis (intramolecular dehydration) reaction in a gas phase state. In addition, when the reaction is carried out in the presence of an inorganic porous catalyst, N-substituted (meth)acrylamide can be obtained with high selectivity and high yield, which is preferable. Although a commercially available inorganic porous catalyst can be used as it is, it is preferable to use the catalyst after calcining in dry air in advance. The calcination temperature is in the range of 300 to 1000°C, preferably 500 to 700°C, and the calcination time is about 0.5 to 10 hours.

[0052] In the gas-phase pyrolysis reaction of step (B), the amount of inorganic porous catalyst used varies depending on the amount of amide compound fed, but it is preferable to feed 0.05 to 10 kg / h of amide compound per 1 kg of catalyst, and under these conditions, the reaction can be carried out continuously for 100 hours or more. If the amount of amide compound fed per 1 kg of catalyst is less than 0.05 kg / h, the contact time of the amide compound with the catalyst becomes long, and the selectivity of the reaction decreases due to the progress of side reactions, while if the amount fed is more than 10 kg / h, the contact time is insufficient, and the conversion rate of the amide compound decreases, which is not preferable. The inorganic porous catalyst can be reused by burning the coking material under a dry air stream.

[0053] In the gas-phase pyrolysis reaction in step (B), the reaction temperature is suitably in the range of 250 to 500°C, preferably 300 to 400°C. If the reaction temperature is lower than 250°C, the conversion rate of the amide compound is low, leading to a decrease in productivity. On the other hand, if the reaction temperature is higher than 500°C, the proportion of side reactions such as the generation of coking increases, and there is a possibility of a decrease in the yield of N-substituted (meth)acrylamide and a sudden decrease in catalytic activity, which is not preferable. In the case of gas-phase pyrolysis, N-substituted (meth)acrylamide can be produced in a good yield without using a polymerization inhibitor, but from the viewpoint of preventing polymerization during storage and purification of the crude monomer of the obtained N-substituted (meth)acrylamide, it is preferable to use a polymerization inhibitor in the pyrolysis step. In addition, as the polymerization inhibitor, a known radical polymerization inhibitor used in the liquid-phase pyrolysis reaction can be used.

[0054] In the gas-phase pyrolysis reaction of step (B), the amide compound may be heated and evaporated under reduced pressure using a falling film evaporator, thin film evaporator, evaporation kettle, or the like, and then ventilated to the inorganic porous catalyst layer. The degree of vacuum is 10 to 130 hPa, preferably 40 to 100 hPa, and the heating temperature for evaporation is 240 to 270° C. During evaporation, the amide compound gas may be diluted with a substance inert to the reaction, such as nitrogen, helium, argon, or a hydrocarbon.

[0055] The reaction in step (B) may use a solvent as necessary. The reaction solvent is not particularly limited, and any common solvent may be used as long as it does not cause a side reaction with the starting material, product, or catalyst of the reaction. When a solvent is used, the appropriate range is usually 10 to 1000% by weight, preferably 50 to 500% by weight, based on the amide compound in the case of liquid-phase pyrolysis.

[0056] In the reaction of step (B), after the liquid or gas phase pyrolysis (intramolecular dehydration) reaction, the generated N-substituted (meth)acrylamide and water are cooled by a water-cooled condenser or the like, and can be obtained as a crude monomer. The crude monomer can be directly distilled, washed with a solvent, extracted, reprecipitated, recrystallized, or the like to isolate the N-substituted (meth)acrylamide, and a high-purity purified product can be obtained. The organic solvent that can be used for washing, extraction, and recrystallization may be appropriately selected depending on the type of N-substituted (meth)acrylamide, and examples of such organic solvents include toluene, benzene, diisopropyl ether, methyl isobutyl ketone, ethyl acetate, propyl acetate, butyl acetate, octanol, decanol, n-hexane, and cyclohexane. EXAMPLES

[0057] The present invention will be further described below with reference to examples, but the present invention is not limited to these experimental examples. The abbreviations of the Lewis acid catalyst (a), inorganic porous catalyst (b), organic acid or its derivative (c), amine or amine salt (d), other compound (e) and N-substituted (meth)acrylamide (f) described in the examples and comparative examples are as follows. (a): Lewis acid catalyst a-1: Lanthanum triflate (a reagent from Tokyo Chemical Industry Co., Ltd.) a-2: Zinc triflate (a reagent from Tokyo Chemical Industry Co., Ltd.) a-3: Boric acid (Fujifilm Wako Pure Chemical reagent) a-4: Phenylboronic acid (a reagent from Tokyo Chemical Industry Co., Ltd.) a-5: 2,4-bis(trifluoromethyl)phenylboronic acid (a reagent from Tokyo Chemical Industry Co., Ltd.) a-6: Methylboronic acid (Sigma Aldrich reagent) (b): Inorganic porous catalyst b-1: Silica gel (Tokyo Chemical Industry Co., Ltd., spherical, 60 μm) b-2: Mesoporous silica (Sigma Aldrich reagent, SBA-15) b-3: Silica alumina (N631HN, particles, made by JGC Catalysts and Chemicals) b-4: Silica sand (Tokai Kogyosha's Powder Series TH1325, silica 66 mol%) b-5: Kaolin (Hayashi Kasei's Eckalite 1, powder, silica 46 mol%) b-6: Synthetic aluminum silicate (Kyowa Chemical Industry's Kyoward 700PEL, fine powder) (c): Organic acid or its derivative c-1: Lactic acid (Fujifilm Wako Pure Chemical Co., Ltd. reagent) c-2: DL-lactide (a reagent from Tokyo Chemical Industry Co., Ltd.) c-3: 2-Hydroxyisobutyric acid (a reagent from Tokyo Chemical Industry Co., Ltd.) c-4: 3-hydroxypropionic acid (a reagent from Tokyo Chemical Industry Co., Ltd.) c-5: Polylactic acid (Sigma Aldrich Reagent, Resomer R202H) (d) Amines or amine salts d-1: Morpholine d-2: Diethylamine d-3: Stearylamine d-4: Phenylamine d-5: Dimethylamine hydrochloride (e): Other compounds e-1: Triethylamine (tertiary amine compound) e-2: 4-(N,N-dimethylamino)pyridine (tertiary amine compound) e-3: Saturated aqueous solution of sodium hydroxide (inorganic alkali) e-4: Xylene (solvent) e-5: N-butylpyrrolidone (solvent) e-6: Hydroquinone monomethyl ether (polymerization inhibitor) e-7: 2,2,6,6-tetramethylpiperidine-1-oxyl (polymerization inhibitor) (f): N-substituted (meth)acrylamide f-1: Acryloylmorpholine (ACMO, a registered trademark of KJ Chemicals) f-2: N,N-diethylacrylamide (DEAA, a registered trademark of KJ Chemicals) f-3: N-stearyl methacrylamide f-4: N-phenylacrylamide f-5: N,N-Dimethylacrylamide (DMAA, a registered trademark of KJ Chemicals)

[0058] Example 1 (A-1) 180.2g (2.0mol) of lactic acid (c-1), 234.4g (0.40mol) of lanthanum triflate (a-1) and 174.2g (2.0mol) of morpholine (d-1) were charged into a 1000mL flask equipped with a stirrer, a thermometer and a condenser with a distillation column, and a mixture was prepared by stirring. The mixture was heated to 120°C while stirring, and the reaction was carried out for 0.5 hours while distilling off the by-product water. The reaction solution was then returned to room temperature, and the reaction solution was analyzed by gas chromatography analysis (GC) and chromatography mass spectrometry (GC-MS), confirming the production of the intermediate amide compound, with a yield of 88%.

[0059] (B-1) As a catalyst, silica gel (b-1) was used after calcination at 500 ° C for 3 hours under a dry air stream. 150 g of the calcined catalyst (b-1) was packed into a vertical stainless steel reaction tube (inner diameter 23.0 mm, length 600 mm). The reaction tube was heated to 250 ° C to 280 ° C in an electric furnace under a reduced pressure of 40 Torr, the intermediate amide compound obtained in the (A-1) step was supplied to the top of the reaction tube, and the gas coming out of the reaction tube was condensed with cooling water at 20 ° C. The gas phase pyrolysis reaction was carried out for 20 hours, after which the reaction tube was returned to room temperature and normal pressure, and the condensate was analyzed by GC and GC-MS to confirm the generation of the target compound acryloylmorpholine (f-1), with a yield of 82%.

[0060] Examples 2 to 8 In Example 1, the starting material, catalyst, other compounds (solvent, cocatalyst, polymerization inhibitor, etc.) and reaction conditions of each step were changed as shown in Table 1, and Examples 2 to 8 were carried out in the same manner as in Example 1 to obtain the respective target compounds. The results are shown in Table 1. When the reaction in step (A) is carried out under reduced pressure or increased pressure, it is carried out using a reduced pressure device and an apparatus capable of handling increased pressure, respectively. When the reaction in step (B) is carried out in a liquid phase, after the reaction in step (A) is completed, the reaction device is not changed, and the catalyst used in step (B) and the like are added to the resulting product mixture, and the reaction in step (B) can be continued. In step (B), a crude product of an intermediate amide compound may be used, and it is preferable to use a purified product obtained by removing the solvent or distillation as necessary.

[0061] [Table 1]

[0062] Comparative Examples 1 to 3 and Reference Example 1 In Example 1, the starting materials, catalysts, other compounds (solvents, cocatalysts, polymerization inhibitors, etc.) and the reaction conditions of each step were changed as shown in Table 2, and Comparative Examples 1 to 3 and Reference Example 1 were carried out in the same manner as in Example 1, and the results are shown in Table 2. In both Comparative Examples 1 and 2, the intermediate amide compound was hardly produced in step (A), so the reaction in step (B) was not carried out. The results of the reaction solution analysis showed that in Comparative Example 1, since an unsaturated group-containing carboxylic acid was used, most of the products were Michael adducts of acrylic acid and morpholine, and only a small amount of intermediate amide compound was obtained. In Comparative Example 2, since a Lewis acid catalyst was not used, an intermediate amide compound was not detected. From the results of Comparative Example 3, it was found that when an inorganic porous catalyst was not used in step (B), the intramolecular dehydration reaction of the amide compound did not proceed. In addition, from the results of Reference Example 1, it is clear that the target N-substituted (meth)acrylamide can be obtained even if alumina is used as the inorganic porous catalyst, but if the content of silica in the inorganic porous catalyst is 30 mol% or more, the reaction yield is significantly improved.

[0063] [Table 2] [Industrial Applicability]

[0064] As described above, the method of the present invention uses organic acids derived from biomass or organic acids derived from natural materials as starting materials, and reacts them with amines or amine salts in the presence of a Lewis acid catalyst to obtain amide compounds, and the obtained amide compounds can be produced by intramolecular dehydration in the presence of an inorganic porous catalyst to produce N-substituted (meth)acrylamides. The N-substituted (meth)acrylamides obtained by the production method of the present invention can be easily polymerized alone or with other polymerizable monomers to obtain various functional polymers. N-substituted (meth)acrylamides can be suitably used in a wide variety of fields, such as paints, pressure sensitive adhesives, adhesives, various coating agents, papermaking agents such as paper strength agents, polymer flocculants, polymer modifiers, dispersants, thickeners, synthetic raw materials for contact lenses and biogels, and reactive diluents for UV curable resins.

Claims

1. One or more organic acids, cyclic dimers of organic acids, oligomers of organic acids, or polymers of organic acids selected from the group consisting of lactic acid, 3-hydroxypropionic acid, 2-hydroxyisobutyric acid, and 3-hydroxyisobutyric acid; A method for producing an N-substituted (meth)acrylamide, comprising the steps of: step (A) is a step of subjecting an organic acid, a cyclic dimer of an organic acid, an oligomer of an organic acid, or a polymer of an organic acid to an intermolecular dehydration condensation or ring-opening reaction with an amine or an amine salt in the presence of a Lewis acid to obtain an amide compound; Step (B) is a step of obtaining an N-substituted (meth)acrylamide by subjecting the amide compound obtained in step (A) to gas-phase dehydration under reduced pressure in the presence of an inorganic porous catalyst containing 30 mol % or more of silica, or by adding an inorganic porous catalyst containing 30 mol % or more of silica to the amide compound obtained in step (A) and subjecting it to liquid-phase dehydration.

2. 2. The method for producing an N-substituted (meth)acrylamide according to claim 1, wherein the amine is a primary amine or a secondary amine represented by the general formula [1]. 【Chemistry 1】 (In the formula, R １ and R ２ are each a hydrogen atom (provided that R １ and R ２ and R are both hydrogen atoms.) or a linear alkyl group or a hydroxyalkylene group having 1 to 36 carbon atoms, an alkenyl group or an alkyl ether group having 2 to 36 carbon atoms, a branched alkyl group or an alicyclic hydrocarbon having 3 to 36 carbon atoms, or an aromatic hydrocarbon having 6 to 36 carbon atoms; １ and R ２ may combine with the nitrogen atom carrying them to form a saturated 5- to 7-membered ring with an oxygen atom.

3. 3. The method for producing N-substituted (meth)acrylamides according to claim 1 or 2, wherein the amine salt is a salt formed by neutralizing a primary amine or a secondary amine with an acid.

4. The method for producing N-substituted (meth)acrylamide according to claim 3, wherein the acid is hydrofluoric acid, hydrochloric acid, hydrobromic acid, hydroiodic acid, nitric acid, sulfuric acid, phosphoric acid, carbonic acid, formic acid, acetic acid, oxalic acid, adipic acid, glutaric acid, salicylic acid, succinic acid, malonic acid, or p-toluenesulfonic acid.

5. The method for producing an N-substituted (meth)acrylamide according to any one of claims 1 to 4, characterized in that the Lewis acid is a compound obtained by combining one or more metal atoms selected from the group consisting of boron, aluminum, scandium, titanium, iron, zinc, arsenic, zirconium, niobium, cadmium, indium, tin, antimony, hafnium, mercury, and lanthanoids, with one or more electron-withdrawing groups selected from the group consisting of halogen groups, trifluoromethyl groups, trifluoromethanesulfonyl groups, sulfonyl groups, methanesulfonyl groups, trifluoroacetyl groups, and nitro groups.

6. 6. The method for producing an N-substituted (meth)acrylamide according to any one of claims 1 to 5, wherein the Lewis acid is a boron compound.

7. 7. The method for producing an N-substituted (meth)acrylamide according to claim 1, wherein the Lewis acid is an organoboron compound.

8. 8. The method for producing N-substituted (meth)acrylamides according to claim 7, wherein the organoboron compound is a boronic acid or a boronic acid derivative.

9. The method for producing an N-substituted (meth)acrylamide according to claim 5, wherein the reaction in the step (A) further uses a tertiary amine compound as a promoter.

10. The method for producing an N-substituted (meth)acrylamide according to claim 1, wherein the reaction in step (A) is carried out without a solvent or in the presence of an organic solvent.

11. The method for producing an N-substituted (meth)acrylamide according to any one of claims 1 to 10, wherein the inorganic porous catalyst is in the form of a powder, fine particles, granules or a thin film.

12. The method for producing an N-substituted (meth)acrylamide according to any one of claims 1 to 11, wherein the inorganic porous catalyst containing 30 mol% or more of silica is one or more selected from the group consisting of silica gel, mesoporous silica, silica alumina, zeolite, aluminosilicate, silica sand, kaolin, and aluminum silicate.

13. The method for producing an N-substituted (meth)acrylamide according to any one of claims 1 to 12, characterized in that the N-substituted (meth)acrylamide is an N-monosubstituted (meth)acrylamide and an N,N-disubstituted (meth)acrylamide represented by the general formula [2]. 【Chemistry 2】 (In the formula, R １ and R ２ are each a hydrogen atom (provided that R １ and R ２ and R are both hydrogen atoms.) or a linear alkyl group or hydroxyalkylene group having 1 to 36 carbon atoms, an alkenyl group or alkyl ether group having 2 to 36 carbon atoms, a branched alkyl group or alicyclic hydrocarbon having 3 to 36 carbon atoms, or an aromatic hydrocarbon having 6 to 36 carbon atoms, １ and R ２ may combine with the nitrogen atom carrying them to form a saturated 5- to 7-membered ring with an oxygen atom. ３ represents a hydrogen atom or a methyl group.

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