JPH0245456A - Production of unsaturated carboxamide - Google Patents

Abstract

PURPOSE:To obtain a compound useful as a flocculant, precipitant, thickener, adhesive, paper processing agent, resin modifier, etc., in good yield by reacting a beta-alkoxy-substituted carboxylic acid ester with a primary amine and then eliminating an alcohol using a catalyst. CONSTITUTION:A beta-alkoxy-substituted carboxylic acid ester expressed by formula I (R1 is H or methyl; R2 and R3 are 1-3C alkyl) is reacted with a primary amine expressed by the formula H2N-R4 (R4 is 1-9C alkyl or N,N-dialkyl- substltuted aminoalkyl having 1-4C alkyl chain) at 40-180 deg.C to provide a beta- alkoxy-substituted carboxamide, which is then reacted, preferably in the presence of a polymerization inhibitor (e.g., hydroquinone) to eliminate an alcohol using an alkaline earth metal hydroxide [e.g., Mg(OH)2 or Ca(OH)2] at 50-170 deg.C, form an unsaturated group and afford the objective substance expressed by formula II.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides - Ritual (III) C11, CC0NHR4 (III) (wherein, R6 is the same as R9 in general formula (1). Formula (II
) Same as R4. ) (hereinafter abbreviated as N-substituted amide).

The N-substituted amides provided by the present invention can be used as flocculants,
It is a useful compound with a wide range of uses, such as precipitants, thickeners, adhesives, paper processing agents, and resin modifiers.

[Prior Art and Problems to be Solved by the Invention] The N-substituted amide of the present invention can generally be produced by amicilysis of an unsaturated carboxylic acid ester and an amino compound. However, when amithrisis of an unsaturated carboxylic acid ester and an amino compound occurs, Michael addition to the double bond of the amino compound occurs, resulting in a low selectivity of the target product in the reaction, and it is difficult to regenerate the double bond from the Michael adduct. requires a step of thermal decomposition at a high temperature of 180 to 300°C to remove the added amino compound, but at this time, side reactions such as the formation of polymers occur, reducing the yield of the target product. It decreases significantly (Japanese Patent Application Laid-open No. 50-111016
In order to suppress this side reaction, a lower alcohol is first added to the double bond, then amithrisis is performed, and then dealcoholization is performed at high temperature to regenerate the double bond and obtain the desired product ( JP-A No. 49-66623, LIS
P-2534585, 0SP-2702822) is disclosed.

Although this method is effective for the purpose of preventing Michael addition of amino compounds to double bonds, side reactions such as polymerization occur when regenerating double bonds by dealcoholization, resulting in the yield of the target product. has serious drawbacks that reduce the rate. In addition, as a method for protecting double bonds, cyclopentadiene is added to the double bond by Diels-Alder reaction, and after completion of amitrilysis, cyclopentadiene is removed by thermal decomposition (JP-A-49-66625 et al. ) are also disclosed. However, even in this method, the formation of by-products is inevitable, a separation and recovery process is required for the desorbed cyclopentadiene from the target product, and the contamination of trace amounts of cyclopentadiene into the product is avoided. However, it has drawbacks such as deterioration of product quality.

[Means for Solving the Problems] As a result of extensive research into a method for producing tri-substituted amides in good yield without producing by-products, the present inventors found that the general formula (
1) %Formula%(1) (In the formula, R1 represents hydrogen or a methyl group, R2, R3
represents an alkyl group having 1 to 3 carbon atoms.
Alkoxy-substituted carboxylic ester (hereinafter abbreviated as β-alkoxy-substituted carboxylic ester).

) and a -grade amine, and then using a catalyst to remove the alcohol under mild conditions to regenerate the double bond, we discovered that it was possible to produce the desired product in higher yield. , we have completed the present invention.

The present invention provides a β-alkoxy substituted carboxylic acid ester,
General formula (II) HJ-Rn (II)
(wherein, R4 represents an alkyl group having 1 to 9 carbon atoms or an N,N-dialkyl-substituted aminoalkyl group in which the alkyl chain has 1 to 4 carbon atoms, respectively) (hereinafter, - amine) to synthesize a β-alkoxy monocarboxylic acid amide, and then remove the alcohol using an alkaline earth metal hydroxide to form an unsaturated group. Featured N-
The present invention relates to a method for producing substituted amides.

The present invention will be explained in detail below.

Examples of the β-alkoxy-substituted carboxylic acid ester used in the present invention include methyl β-methoxypropionate, ethyl β-methoxypropionate, n-propyl β-methoxypropionate, isopropyl β-methoxypropionate, and β-methoxypropionate. Methyl methoxyisobutyrate, ethyl β-methoxyisobutyrate, n-propyl β-methoxyisobutyrate,
Isopropyl β-methoxyisobutyrate, Methyl β-ethoxypropionate, Ethyl β-ethoxypropionate, β
-n-propyl ethoxypropionate, isopropyl β-ethoxypropionate, methyl β-ethoxyisobutyrate, ethyl β-ethoxyisobutyrate, n-ethoxyisobutyrate
-propyl, β-ethoxyisobutyrate isopropyl, β-
Methyl isopropoxypropionate, ethyl β-isopropoxypropionate, n-propyl β-isopropoxypropionate, isopropyl β-isopropoxypropionate, methyl β-isopropoxyisobutyrate, ethyl β-isopropoxyisobutyrate, β - n-propyl isopropoxyisoacetate, β-isopropyl isopropoxyisobutyrate, ethyl β-n-propoxypropionate, β-
Ethyl n-propoxypropionate, toprovir β-lobroboxyprobionic acid, isopropyl β-n-proboxybrobionic acid, methyl β-n-propoxyisobutyrate, ethyl β-n-propoxyisobutyrate, β-n- Examples include n-propyl propoxyisobutyrate and isopropyl β-n-propoxyisobutyrate.

These β-alkoxy Zta carboxylic acid alkyl esters can be obtained by a known addition reaction of an alcohol to the double bond of an alkyl ester of acrylic acid or methacrylic acid.

-grade amines include methylamine, ethylamine, n
-propylamine, isopropylamine, n-butylamine, isobutylamine, t-butylamine, S-butylamine, S-pentylamine, 2-aminopentane,
3-aminopentane, t-pentylamine, 1.2-dimethylpropylamine, isopentylamine, 2-methylbutylamine, neopentylamine, n-hexylamine, 1.3-dimethyl-n-butylamine, rhoheptylamine, 2-hebutylamine, 4-hebutylamine, n-octylamine, 2-ethylhexylamine, 1
．． 5-dimethylhexylamine, 2-aminooctane,
Alkylamines having 1 to 9 carbon atoms such as n-nonylamine, N,N-dimethylaminomethylamine, N,N-dimethylaminoethylamine, NN-dimethylaminopropylamine, N,N dimethylaminobutylamine, N,
N,N such as N-diethylaminomethylamine, N,N-diethylaminoethylamine, N,II-diethylaminoethylamine, N,N-diethylaminobutylamine, etc.
-dialkyl-substituted aminoalkylamines.

In the present invention, first, β-alkoxy-substituted carboxylic acid ester and primary amine are subjected to amithrilysis.
-Alkoxy-substituted carboxylic acid amide is obtained.

The molar ratio of the primary amine to the β-alkoxy substituted carboxylic acid ester is preferably in the range of 0.3 to 3.

When the boiling point of the primary amine to be used is higher than the boiling point of the alcohol that is produced in amithrisis, the reaction pressure is preferably atmospheric pressure or reduced pressure, and the preferred reaction pressure is 50 to 76.
0mn+Hg.

The reaction temperature is preferably carried out above the boiling point of the alcohol produced as a by-product, and is preferably 40 to 180°C, although it varies depending on the reaction pressure and the boiling point of the primary amine used. In this case, it is advantageous to proceed with the reaction while distilling off the by-product alcohol from the reaction system to increase the reaction rate and conversion rate.

Additionally, if the boiling point of the primary amine used is lower than the boiling point of the alcohol by-produced during amitrilysis, when attempting to distill off the by-product alcohol, the primary amine as a raw material will come out of the system first. It is necessary to use a closed reactor that can be pressurized. The reaction pressure at this time varies depending on the reaction temperature, but the spontaneously generated pressure is sufficient and is about 1 to 10 atm. in this case,
Since the by-product alcohol cannot be distilled off from the reaction system, the reaction temperature must be raised to a higher temperature, and the desired reaction temperature varies depending on the raw materials used, but is 100 to 180°C.
is desirable.

Under pressure as described above, it is impossible to distill off the by-product alcohol from the reaction system, so the equilibrium cannot be shifted and the conversion rate cannot be increased above a certain level. The limit of this conversion rate varies depending on the raw material primary amine and β-alkoxy-substituted carboxylic acid ester, but
It is 60%.

Further, since the primary amine is basic, this reaction proceeds even without a catalyst, but it is also possible to add a known basic amitrisis catalyst.

The obtained β-alkoxy-substituted carboxylic acid amide may be purified by vacuum distillation and used in the next step, but after the reaction is completed, unreacted raw materials and low-boiling byproducts are simply distilled off. It is also possible to use it in reactions.

Next, the real alcohol is eliminated from the β-alkoxy-substituted carboxylic acid amide to synthesize the N-substituted amide. At this time, when the target product is produced by conventional graphing at high temperature, A large amount of undesirable by-products such as polymers are produced, which complicates the purification of the target product and significantly reduces the yield. Therefore, in the present invention, it is important to eliminate the alcohol under mild conditions using a catalyst, and an alkaline earth metal hydroxide is used as the catalyst.

Examples of the alkaline earth metal hydroxide of the present invention include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, and the like.

These alkaline earth metal hydroxides can be added to the reaction system after being dissolved in an inert solvent, or can be added in the form of a solid.

It is preferable to carry out the reaction at low temperature to suppress side reactions.
The reaction temperature is preferably in the range of 50 to 170°C.

The reaction pressure is suitably 50 to 760 smHg, and it is desirable to proceed with the reaction while distilling off the alcohol produced from the viewpoint of increasing the reaction rate.

It is also possible to use a solvent as another means of preventing side reactions.Although it is not necessary to use a solvent in the present invention, even if a solvent is used, it may lead to a decrease in the yield of the product. high yields can be maintained.

As a solvent, N,N-dimethylformamide, N.

Examples include N-dimethylacetamide, N,N-dimethylsulfoxide, toluene, xylene, and the like.

After the reaction is completed, the alkaline earth metal hydroxide in the reaction solution is neutralized with a mineral acid such as hydrochloric acid or sulfuric acid, or an organic acid such as acetic acid, or the waste catalyst is removed by an extraction operation, or the insoluble catalyst is removed. After filtering or removing by centrifugation,
Purify the target product by distillation or the like.

Note that during the reaction and during the purification of the target product, it is preferable to add a known polymerization inhibitor, and suitable examples of the polymerization inhibitor include hydroquinone, hydroquinone monomethyl ether, phenothiazine, cuperone, and the like.

[Example] Hereinafter, the present invention will be specifically explained with reference to Examples.

Example 1 [Amitrisis] In a four-cylinder flask equipped with a stirrer and a column equipped with a fractionator at the top and filled with a glass Uschig ring, 118.1 g (1°0 mol) of methyl β-methoxypropionate and N,N were added. -dimethylaminopropylamine 204.3g
(2.0 mol) was added, and the reaction proceeded at 150° C. while distilling off the methanol produced.

The reaction was completed in 8 hours, and after the reaction, unreacted N, N-
Dimethylaminopropylamine was distilled off under reduced pressure. After further distillation of low boiling fractions, 190. A reaction solution of Og was obtained. N-(N', N'-dimethylaminopropyl)-β- of the reaction solution
The content of methoxypropioamide is 90%.

[Alcohol elimination]

The reaction solution obtained in the above amithrisis was put into a reactor in the same manner as in the above amithrisis, and calcium hydroxide 4 was added as a catalyst.
．． The reaction was carried out at 125°C and 1,505 ml by adding 0.0 g of cuperone and 0.6 g of cuperone as a polymerization inhibitor.

The reaction proceeded while the alcohol by-produced during the reaction was distilled off from the reaction system. The reaction was completed in 8 hours, and the resulting reaction solution was purified by vacuum distillation to yield 137.2 g of N,N-dimethylaminopropylacrylamide. I got it. Purity is 99
．． 7%, and the yield was 87.6% (based on methyl β-methoxypropionate donated to the reaction).

Examples 2 to 6 Using the same reaction apparatus as in Example 1 and the raw materials and catalysts in Table 1, the same amicilysis and alcohol elimination reactions as in Example 1 were carried out to synthesize the corresponding N-substituted amides. The results shown in Table 1 were obtained.

(Hereinafter, blank space) Example 7 (Amiturisis) 236.2 (2.0 mol) of methyl β-methoxypropionate and 236 g (4.0 mol) of isopropylamine were placed in a No. 11 autoclave equipped with a stirrer, and the lid was closed. hand,
The temperature was raised to 100°C while stirring. 10 hours later,
The reaction was stopped and cooled, the reaction solution was taken out, and unreacted isopropylamine was distilled off. Furthermore, after distilling off the low boiling fraction, 17
N-isopropyl-β- after 0 reactions yielding 4 g of reaction solution
The content of methoxypropioamide was 90%.

[Alcohol elimination] 174 g of the reaction solution obtained in the above amithrisis was prepared in Example 1.
Calcium hydroxide 8 is added as a catalyst to a reactor similar to
．． 0g, cuperone 0.9g as a polymerization inhibitor was added, and the reaction was carried out at 125°C, 1150ffid. The reaction was proceeded while distilling off the methanol by-produced from the reaction system during the 0 reaction. The 0 reaction was completed in 6 hours. The resulting reaction solution was purified by vacuum distillation to obtain 111.8 g of N-isopropylacrylamide. Purity is 99.2% and yield is 49.
% (based on methyl β-methoxypropionate donated to the reaction).

Examples 8 to 10 Using the same reaction apparatus as in Example 7 and using the raw materials and catalysts in Table 2, the same amicilysis and alcohol elimination reactions as in Example 7 were carried out to synthesize the corresponding N-substituted amides. The results shown in Table 2 were obtained.

(Hereinafter, blank spaces) [Effects of the Invention] According to the method of the present invention, an N-substituted amide can be produced in high yield with few by-products such as polymers. The obtained N-substituted amide can be homopolymerized, quaternized, or directly copolymerized with other vinyl monomers to be used as flocculants, precipitants, thickeners, adhesives, resin modifiers, etc. Suitable high molecular weight polymers can be produced.

Patent applicant: Mitsui Toatsu Chemical Co., Ltd.

Claims (1)

[Claims] 1. General formula (I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R_1 represents hydrogen or a methyl group, R_2,
R_3 represents an alkyl group having 1 to 3 carbon atoms. ) and β-alkoxy-substituted carboxylic acid ester represented by the general formula (
II) H_2N-R_4(II) (wherein R_4 represents an alkyl group having 1 to 9 carbon atoms or an N,N-dialkyl-substituted aminoalkyl group in which the alkyl chain has 1 to 4 carbon atoms, respectively.) A general method characterized in that a β-alkoxy-substituted carboxylic acid amide is synthesized by reacting with a primary amine, and then an unsaturated group is formed by eliminating the alcohol using an alkaline earth metal hydroxide. Formula (III) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (III) (In the formula, R_1 is the same as R_1 in general formula (I). R_4 is the same as R_4 in general formula (II).) A method for producing an N-substituted unsaturated carboxylic acid amide. 2. The alkaline earth metal hydroxide is magnesium hydroxide,
2. A method according to claim 1, which is calcium hydroxide, strontium hydroxide or barium hydroxide.