JPH0248559A - Production of unsaturated carboxylic acid amide - Google Patents

Abstract

PURPOSE:To obtain the title compound useful as a moisture absorbent in high yield under a mild condition without by-products by reacting a beta-alkoxy- substituted carboxylic acid ester with a secondary amine and eliminating an alcohol by using a basic catalyst to form an unsaturated group. CONSTITUTION:A compound (e.g., methyl beta-methoxypropionate) shown by formula I (R1 is H or methyl; R2 and R3 are 1-3C alkyl) is reacted with a secondary amine shown by formula II (R4 and R5 are 1-5C alkyl) to synthesize a beta-alkoxy- substituted carboxylic acid amide. then an alcohol is eliminated by using a basic catalyst (e.g., lithium hydroxide or NaOH) and an unsaturated group is formed to give an N-substituted unsaturated carboxylic acid amide shown by formula III. In this method, amounts of by-products such as polymer are small and the aimed substance can be polymerized alone or copolymerized with another vinyl monomer to give a high molecular weight polymer.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to -binding margin (I[[) (wherein, R1 is the same as R1 in the general formula (+), R4
゜RS is R4. in general formula (II). Same as R5)
N-substituted unsaturated carboxylic acid amide represented by (hereinafter referred to as N
-Abbreviated as substituted amide. ).

The N-substituted amides provided by the present invention are hygroscopic agents,
It is a useful compound that has a wide range of uses such as antifogging agents, separation membranes, 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, in the amitrilysis of an unsaturated carboxylic acid ester and an amino compound, Michael addition to the double bond of the amino compound occurs, resulting in a low selectivity of the target product in the reaction. In addition, in order to regenerate double bonds from Michael adducts, it is necessary to carry out thermal decomposition at a high temperature of 180 to 300°C to remove the added amino compound, but in this case, the formation of polymers, etc. A side reaction occurs and the yield of the target product decreases significantly (Japanese Patent Application Laid-Open No. 111016/1982). In order to suppress this side reaction, a lower alcohol is first added to the double bond, and then amithrisis is performed, and then , a method for obtaining the desired product by regenerating double bonds by dealcoholization at high temperatures (JP-A No. 49-66623, USP-25345)
85° USP-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 Li Problem) As a result of intensive study on a method for producing N-substituted amides in good yield without producing by-products, the present inventors discovered that β-alkoxy 1ita carboxylic acid ester and secondary They discovered that the desired product could be produced in high yield by reacting it with an amine and then removing the alcohol under mild conditions using a catalyst to regenerate the double bond, thereby completing the present invention. It's arrived.

The present invention provides - binding allowance (1) % formula % () (in the formula, R1 represents hydrogen or a methyl group, pg, R
.

represents an alkyl group having 1 to 3 carbon atoms, β-
Alkoxy-substituted carboxylic ester (hereinafter abbreviated as β-alkoxy-substituted carboxylic ester).

) and - binding allowance (n) HN-R4(It) (wherein, Ra and Rs represent an alkyl group having 1 to 5 carbon atoms) (hereinafter abbreviated as secondary amine) ) to synthesize a β-alkoxy-substituted carboxylic acid amide, and then remove the alcohol using a basic catalyst as a catalyst to form an unsaturated group to produce a N-i-substituted amide. Regarding the method.

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-methoxyisopropionate. Methyl butyrate, ethyl β-methoxyisobutyrate, n-propyl β-methoxyisobutyrate,
Isopropyl β-methoxyisobutyrate, Methyl β-ethoxypropionate, Ethyl β-ethoxypropionate, β
- n-propyl ethoxypropionate, isopropyl β-ethoxydipropionate, methyl β-ethoxyisobutyrate, ethyl β-ethoxyisobutyrate, rhopropyl β-ethoxyisoacetate, isopropyl β-ethoxyisobutyrate, β-
Methyl isopropoxypropionate, ethyl β-impropoxypropionate, n-propyl β-isopropoxypropionate, isopropyl β-isopropoxypropionate, methyl β-isopropoxyisobutyrate, ethyl β-isopropoxyisobutyrate, β- n-propyl isopropoxyisobutyrate, isopropyl β-isopropoxyisobutyrate, methyl β-n-propoxypropionate, β-
Ethyl low-propoxypropionate, low-propyl β-n-propoxypropionate, isopropyl β-n-propoxypropionate, ethyl β-n-propoxyisobutyrate, ethyl β-n-propoxyisobutyrate, β-n-propoxyisobutyric acid n-propyl, isopropyl β-n-propoxyisobutyrate, and the like.

These alkoxy-substituted carboxylic acid alkyl esters can be obtained by adding an alcohol to the double bond of an alkyl ester of acrylic acid or methacrylic acid.

Examples of secondary amines include dimethylamine, diethylamine, N,N-ethylpropylamine, N,N-methylbutylamine, di-n-propylamine, diisopropylamine, N,N-ethylbutylamine, di-n-butylamine, and diisobutylamine. Examples include amines, dibentylamines, and the like.

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

The molar ratio of the secondary 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 secondary amine used is higher than the boiling point of the alcohol by-produced in amitrilysis, the reaction pressure is preferably atmospheric pressure or reduced pressure, and the preferred reaction pressure is 50 to 760.
smHg.

The reaction temperature is preferably higher than 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 secondary amine used. In this case, it is advantageous to proceed with the reaction while distilling the alcohol by-produced from the reaction system to increase the reaction rate and conversion rate.

In addition, if the boiling point of the secondary 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 raw material secondary amine will come out of the system first. It is necessary to use a closed reactor that can be pressurized, such as 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 preferably 100 to 180°C.

Under pressure, 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 beyond a certain level. The limit varies depending on the raw material secondary amine and β-alkoxy-substituted carboxylic acid ester, but is 50~
It is 60%.

Further, since the secondary 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 can be used for this reaction.

Next, an N-substituted amide is synthesized by eliminating the real alcohol from a β-alkoxy-substituted carboxylic acid amide. A large amount of undesirable by-products such as This is important, and a basic catalyst is used as the catalyst.

Examples of the basic catalyst of the present invention include alkali metal alcoholates, alkali metal hydroxides, alkaline earth metal hydroxides or oxides, and alkali metal carbonates.

Examples of the alkali metal alcoholate include sodium methylate, sodium ethylate, potassium methylate, potassium ethylate, and the like.

Examples of the alkali metal hydroxide include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

Examples of alkaline earth metal hydroxides or oxides include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium oxide, calcium oxide, barium oxide, and the like. Further, examples of the alkali metal carbonate include sodium carbonate and potassium carbonate.

These basic catalysts can be added to the reaction system after being dissolved in an inert solvent, or they can be added in solid form.

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.

A suitable reaction pressure is 50 to 760+*mHg, 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 will not result in a decrease in the yield of the product, A good yield can be maintained.

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

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

After the reaction is completed, the basic catalyst 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 undissolved catalyst is filtered or removed. , and then removed by centrifugation, the target product is purified by distillation or the like.

In addition, it is preferable to add a polymerization inhibitor during the reaction and purification of the target product, and examples of the polymerization inhibitor include:
hydroquinone, hydroquinone monomethyl ether,
Phenothiazines, cuperone, etc. are suitable.

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

Example 1 [Amitrisis] 118.1 g (1.0 mol) of methyl β-methoxypropionate and di-n were placed 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. -Propylamine 202.3g (2.0 mol)
was added, and the reaction proceeded while distilling off the methanol produced at 125°C.

The reaction was completed in 16 hours, and after the reaction, unreacted di-n
-Propylamine was distilled off under reduced pressure. Furthermore, the content of N,N-sheet propyl-β-methoxypropioamide in 150.6 g of the reaction solution obtained after distilling off the low-boiling fraction was 90%.

[Alcohol deml] 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.
．． 0g of cuperone was added as a polymerization inhibitor, and the reaction was carried out at 125°C and 150mmHg.

The reaction proceeded while the alcohol by-produced during the reaction was distilled off from the reaction system. The reaction was completed in 4 hours, and the resulting reaction solution was purified by vacuum distillation to obtain N,N-di-n-propylacrylamide 109 .3g was obtained. Purity is 99.5%
The yield was 70.5% (based on methyl β-methoxypropionate donated to the reaction).

Examples 2 to 8 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.

(The following is a blank space) Example 9 [Amiturisis] 236.2 g (2.0 mol) of methyl β-methoxypropionate and 292.5 g (4.0 mol) of diethylamine were placed in a 12 autoclave equipped with a stirrer, and the lid was closed. The temperature was raised to 100°C while stirring. After 10 hours, the reaction was stopped and cooled, and the reaction solution was taken out and unreacted diethylamine was distilled off. After further distilling off the low boiling fraction, 111
The content of N,N-diethyl-β-methoxypropioamide after the 0-reaction yielding 10.0 g of reaction solution was 92.0%.

[Alcohol DeMization] 180.0 g of the reaction solution obtained in the above amithrisis was placed in the same reactor as in Example 1, 4.0 g of lithium hydroxide was added as a catalyst, and 1.0 g of cuperone was added as a polymerization inhibitor. 125°C1L50ff1m)0 reacted with Ig
The reaction proceeded while the methanol by-produced during the reaction was distilled off from the reaction system. The reaction was completed in 4 hours, and the resulting reaction solution was purified by vacuum distillation to obtain 127.7 g of N,N-diethylacrylamide. Ta. The purity was 99.6% and the yield was 50% (based on methyl β-methoxypropionate donated to the reaction).

Examples 10 to 12 Using the same reaction apparatus as in Example 9 and the raw materials and catalysts in Table 2, the same amicilysis and alcohol elimination reactions as in Example 9 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 is homopolymerized or copolymerized with other vinyl monomers to produce high molecular weight polymers suitable for uses such as moisture absorbers, antifogging membranes, separation membranes, and resin modifiers. can do.

Patent applicant: Mitsui Toatsu Chemical Company

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 the β-alkoxy-substituted carboxylic acid ester represented by the general formula (I
I) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (II) (In the formula, R_1 and R_5 represent an alkyl group having 1 to 5 carbon atoms.) By reacting with a secondary amine represented by General formula (III), which is characterized by forming an unsaturated group by synthesizing a substituted carboxylic acid amide and then eliminating the alcohol using a basic catalyst ▲There are mathematical formulas, chemical formulas, tables, etc.▼ ( III) (In the formula, R_1 is the same as R_1 in formula (I).
_4 and R_5 are the same as R_4 and R_5 in formula (II). ) A method for producing an N-substituted unsaturated carboxylic acid amide. 2. Claim 1, wherein the basic catalyst is an alkali metal alcoholate, an alkali metal hydroxide, an alkaline earth metal hydroxide, an alkaline earth metal oxide or an alkali metal carbonate.
Method described. 3. The method according to claim 1, wherein the basic catalyst is sodium methylate, sodium ethylate, potassium methylate or potassium ethylate. 4. The basic catalyst is lithium hydroxide, sodium hydroxide,
2. The method according to claim 1, wherein the hydroxide is potassium hydroxide, rubidium hydroxide or cesium hydroxide. 5. The method according to claim 1, wherein the basic catalyst is magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium oxide, calcium oxide or barium oxide. 6. The method according to claim 1, wherein the basic catalyst is sodium carbonate or potassium carbonate.