JPH0931019A - Polymerization inhibitor for process for producing unsaturated carboxylic acid ester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject polymerization inhibitor comprising a specific (di)thiocarbamic acid (salt), having an excellent polymerization-inhibiting ability for the unsaturated double bond of an unsaturated carboxylic acid ester on the production of the unsaturated carboxylic acid ester, and capable of being easily removed from the produced ester compound. SOLUTION: A polymerization inhibitor for a process for producing an unsaturated carboxylic acid ester comprises (A) a (di)thiocarbamic acid, its metal salt, ammonium salt or amine salt (e.g. diethanoldithiocarbamic acid copper salt, dimethyldithiocarbamic acid copper salt, or piperazinebisdithiocarbomic acid copper salt), and, if necessary, (B) a copper ion-forming compound (e.g. an inorganic acid copper salt such as copper sulfate or copper nitrate, an organic acid copper salt such as copper maleate).

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polymerization inhibitor used in the production of unsaturated carboxylic acid esters.

[0002]

Conventionally, when synthesizing unsaturated carboxylic acid esters, phenothiazines or hydroquinone compounds have been used as a polymerization inhibitor used for suppressing the reaction of unsaturated bonds. ing.

However, when a hydroquinone compound is used, the oxygen concentration in the reaction system decreases as the reaction temperature rises, activating the polymerization of unsaturated bonds, so that a constant amount of oxygen is always used. Must be supplied to the reaction system. In addition, the oxygen causes the reaction solution to be oxidized, resulting in color deterioration of the obtained product. Further, no effect can be expected under basic conditions containing sodium hydroxide and the like. Further, when phenothiazines are used, good effects cannot be expected in an acidic reaction system, and the cost of phenothiazines is high even in a basic reaction system, so that it is not versatile. In view of the above problems, in recent years, use of a copper ion compound chelated with a chelating agent of an amine compound such as acetylacetone or ethylenediaminetetraacetic acid that does not require the coexistence of oxygen has been studied. However, it is very difficult to remove the copper ion-based compound from the system after completion of the reaction, and there is a problem that it inhibits the polymerization of unsaturated bonds when it is used as a product.

[0004]

Means for Solving the Problems As a result of intensive investigations aimed at solving the above-mentioned drawbacks, the present inventors have found that a compound having copper ion immobilized on a compound of the present invention having a metal-immobilizing ability is unsaturated. The present invention has been accomplished by discovering that the addition of a carboxylic acid into a carboxylic acid exerts an excellent polymerization inhibiting effect on unsaturated bonds, and the removal thereof can be easily performed by simple operations such as washing with water and liquid separation.

That is, the present invention relates to dithiocarbamic acid,
Thiocarbamic acid and a polymerization inhibitor for an unsaturated carboxylic acid ester production process comprising one or more compounds (1) selected from the group consisting of metal salts, ammonium salts or amine salts thereof; and the above compound (1) And a polymerization inhibitor for the unsaturated carboxylic acid ester production process comprising the copper ion-forming compound (2).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The process for producing an unsaturated carboxylic acid ester in which the polymerization inhibitor of the present invention is effective is an esterification reaction between an unsaturated carboxylic acid and a compound having one or more hydroxyl groups in the molecule. . Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, maleic acid and the like. Examples of the compound having one or more hydroxyl groups in the molecule include the following (a) to (d). (A) a chain alcohol having 1 to 20 carbon atoms, and a cycloalkyl alcohol having 4 to 30 carbon atoms (b) a phenol in which 1 to 5 hydrogen atoms may be substituted with an alkyl group having 1 to 10 carbon atoms (C) 1 to 20 carbon atoms having two or more hydroxyl groups in the molecule
Chain alcohols and cycloalkylpolyols having 4 to 30 carbon atoms having 2 or more hydroxyl groups in the molecule (d) 1 to 5 hydrogen atoms having 2 or more hydroxyl groups in the molecule having 1 carbon atom Polyphenols which may be substituted with alkyl groups of 10 to 10

Examples of the polymerization inhibitor (1) constituting the polymerization inhibitor of the present invention include the following (a) to (f). (A) C1-C8 linear or cycloalkylthiocarbamic acid (B) Phenylthiocarbamic acid in which 1-5 hydrogen atoms may be substituted with a C1-C10 alkyl group (C) carbon Chain-like or cycloalkyldithiocarbamic acid having a number of 1 to 8 (d) Phenyldithiocarbamic acid in which 1 to 5 hydrogen atoms may be substituted with an alkyl group having a carbon number of 1 to 10 (o) Polyamines (PA) Dithiocarbamic acid (ca) (a) to (o) salts (metal salts, ammonium salts, formed by the reaction of carbon disulfide)
(C1-8 monoalkylamine salt, C1-8 dialkylamine salt, C1-8 trialkylamine salt, or C1-8 quaternary ammonium salt)

Polyamines (PA) used in (e)
Is a compound having two or more imino groups or amino groups in which one or two active hydrogen atoms are bonded to a nitrogen atom, and examples thereof include (PA1) ethylenediamine, propylenediamine, butylenediamine, hexamethylenediamine, Polyethylene such as diethylenetriamine, dipropylenetriamine, dibutylenetriamine, triethylenetetramine, tripropylenetetramine, tributylenetetramine, tetraethylenepentamine, tetrapropylenepentamine, tetrabutylenepentamine, N, N ′ dimethylethylenediamine, pentaethylenehexamine Alkylene polyamines (PA2) phenylenediamine, 4-aminodiphenylamine, xylenediamine and other polyphenyl polyamines (PA3) melamine, piperazine, 1-aminoethyl pipet Examples include cyclic polyamine (PA4) monomethylaminopropylamine such as azine, methyliminobispropylamine, 1,3-bis (aminomethyl) cyclohexane, amine such as aminophenyl ether, and the like. Of these, preferred are piperazine, ethylenediamine and N, N ′ dimethylethylenediamine.

The reaction between polyamines (PA) and carbon disulfide is such that the amino group of polyamines (PA) reacts with carbon disulfide to form dithiocarbamic acid, and the reaction usually proceeds at room temperature to form a catalyst. Etc. are not necessary. As a reaction method, (PA) and carbon disulfide may be charged into a reaction vessel equipped with a stirring / cooling device, or one of them may be added dropwise and mixed and stirred, and the reaction time is usually about 5 hours at room temperature. .

As the metal in the metal salt (f), alkali metals such as sodium and potassium, alkaline earth metals such as magnesium and calcium, iron, nickel,
Examples include transition metals such as copper and zinc.

Specific examples of (a) include, for example, dimethylthiocarbamic acid, diethylthiocarbamic acid, dipropylthiocarbamic acid, dibutylthiocarbamic acid,
Examples thereof include cyclohexylthiocarbamic acid, ethylhexylthiocarbamic acid, and diethanoldithiocarbamic acid. Specific examples of (a) include phenylthiocarbamic acid, methylphenylthiocarbamic acid, diethylphenylthiocarbamic acid, and the like. Specific examples of (c) include dimethyldithiocarbamic acid, diethyldithiocarbamic acid, dipropyldithiocarbamic acid, dibutyldithiocarbamic acid, cyclohexyldithiocarbamic acid, ethylhexyldithiocarbamic acid, and diethanoldithiocarbamic acid. Specific examples of (d) include phenyldithiocarbamic acid, methyldiphenylthiocarbamic acid, diethylphenyldithiocarbamic acid, and the like. Specific examples of (e) include piperazine bisdithiocarbamic acid, ethylenebisdithiocarbamic acid, N, N ′ dimethylethylenebisdithiocarbamic acid, and diethylenetrisdithiocarbamic acid. Examples of (f) include potassium dimethylthiocarbamate, sodium diethylthiocarbamate, copper dipropyldithiocarbamate, copper dibutyldithiocarbamate, copper diethanoldithiocarbamate, ammonium cyclohexylthiocarbamate, and dimethylamine phenylthiocarbamate. Salt, methylphenyldithiocarbamic acid piperazine salt,
Piperazine bisdithiocarbamic acid piperazine salt, and the like.

Among these, the preferable one is (c)
They are (e) and (f). More preferred are dimethylthiocarbamic acid, diethylthiocarbamic acid, dipropylthiocarbamic acid, dibutyldithiocarbamic acid, diethanoldithiocarbamic acid copper salt, piperazine bisdithiocarbamic acid, copper dibutyldithiocarbamic acid, piperazine bisdithiocarbamic acid piperazine salt,
It is.

In the present invention, examples of the copper ion-forming compound (2) include copper salts of inorganic acids such as copper sulfate and copper nitrate and / or copper salts of organic acids such as copper acetate and copper maleate. .

The polymerization inhibitor of the present invention comprises the compound (1) or the compounds (1) and (2), and is used in the process for producing an unsaturated carboxylic acid ester. The amount added is 100 parts by weight of unsaturated carboxylic acid,
Addition of 0.001 to 10 parts by weight is preferable, and addition of 0.005 to 0.1 part by weight is particularly preferable. When the compounds (1) and (2) are used in combination, the amount of the compound (2) is preferably about the equivalent amount necessary for forming the salt of (1).

The addition method of the polymerization inhibitor of the present invention is preferably the following addition method to the unsaturated carboxylic acid. Here, (a) to (f) are those exemplified above as the compound (1). That is, the methods (A) to (C) are addition methods for forming the copper salt of (1), and (D)
The method (1) is a method using the copper salt of (1). When the compounds (1) and (2) are used in combination as described below, they may be added separately. A method of adding a mixture of (a) to (e) or (f) which is not a copper salt and (2) to the unsaturated carboxylic acid (A). (B) A method of previously adding the compound (2) to the unsaturated carboxylic acid, and then adding (A) to (E) or (F) which is not a copper salt. (C) A method of previously adding (a) to (e) or (f) which is not a copper salt to the unsaturated carboxylic acid, and then adding the compound (2). (D) A method of adding a copper salt (f) to the unsaturated carboxylic acid.

[0016]

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. In addition, the molecular weight in an Example represents a number average molecular weight, and a part represents a weight part.

Production Example 1 Water 3 in a reaction vessel that can be cooled and stirred and that can be replaced with nitrogen
00 parts and 70 parts of piperazine were charged and stirred at 200 rpm. After confirming that the solid matter in the reaction vessel was dissolved, 160 parts of carbon disulfide was added dropwise at 35 ° C. under a nitrogen atmosphere, and after completion of the addition, aging was carried out at the same temperature for 3 hours to give piperazine bisdithiocarbamine. A 40% aqueous solution of acid was obtained. After this, transfer this 40% aqueous solution to an evaporation dish,
Polymerization inhibitor 1 was obtained by drying in a circulating air dryer at 0 ° C.

Production Example 2 Water 3 in a reaction vessel capable of cooling / stirring and nitrogen substitution
70 parts, calcium hydroxide 180 parts, N, N 'dimethylethylenediamine 70 parts, 50% by weight of dimethylamine
140 parts of an aqueous solution was charged and stirred at 200 rpm. After confirming that the solid matter in the reaction vessel was dissolved, 240 parts of carbon disulfide was added dropwise at 35 ° C. under a nitrogen atmosphere, and after completion of the addition, aging was carried out at the same temperature for 3 hours to obtain N, N ′. A mixture of dimethylbisdithiocarbamic acid calcium salt and dimethyldithiocarbamic acid calcium salt was obtained. Thereafter, 100 parts of a 50 wt% copper sulfate aqueous solution was added, and the resulting precipitate was separated by filtration, washed with water and dried to obtain a polymerization inhibitor 2.

Production Example 3 Water 3 was placed in a reaction vessel capable of cooling and stirring and capable of nitrogen substitution.
200 parts of 70 parts and di-n-butylamine were charged to 200
Stir at rpm. After confirming that the solid matter in the reaction vessel was dissolved, carbon disulfide 7 was added at 35 ° C. under a nitrogen atmosphere.
6 parts was added dropwise, and after completion of the addition, aging was carried out at the same temperature for 3 hours to obtain a 48% aqueous solution of di-n-butyldithiocarbamic acid di-n-butylamine salt. Then, this 48% aqueous solution was transferred to an evaporation dish and dried in a circulating air dryer at 130 ° C. to obtain a polymerization inhibitor 3.

Production Example 4 Water 3 was placed in a reaction vessel which can be cooled and stirred and which can be replaced with nitrogen.
70 parts, sodium hydroxide 56 parts, and 2-methylbenzylamine 121 parts were charged and stirred at 200 rpm. After confirming that the solid substance in the reaction vessel was dissolved, under a nitrogen atmosphere, 76 parts of carbon disulfide was added dropwise, and after completion of the addition, aging was carried out at the same temperature for 3 hours to obtain 2-methylbenzyl. A 40% aqueous solution of dithiocarbamic acid sodium salt was obtained. After this, transfer this 40% aqueous solution to an evaporation dish,
Polymerization inhibitor 4 was obtained by drying in a circulating air dryer at 0 ° C.

Examples 1 to 12 Into a mixture of 50 parts of acrylic acid and 50 parts of methacrylic acid, as shown in Table 1, 0.01 parts of polymerization inhibitors 1 to 4, commercially available methyldithiocarbamic acid and commercially available phenyldithiocarbamic acid are added respectively. Was added. In addition, in Examples 3 to 6 and 9 to 12, 0.03 parts of copper sulfate was previously added to methacrylic acid, and in Examples 7 to 12, sodium hydroxide was added to adjust the solution to have a basic pH of 12. did. Table 1 shows the results of measuring the polymerization initiation temperature by raising the temperature of the prepared sample with a differential scanning calorimeter at a rate of 20 ° C to 20 ° C / min.

Comparative Examples 1 to 5 As a comparative example, 0.01 parts of methylhydroquinone and 0.01 parts of phenothiazine were added to a mixture of 50 parts of acrylic acid and 50 parts of methacrylic acid and mixed. In Comparative Examples 2 and 4, sodium hydroxide was added to adjust the solution to pH 12
Was adjusted to basicity. Table 1 shows the results of measuring the polymerization initiation temperature by raising the temperature of the prepared sample with a differential scanning calorimeter at a rate of 20 ° C to 20 ° C / min.

[0023]

[Table 1]

[0024]

INDUSTRIAL APPLICABILITY The polymerization inhibitor of the present invention has the ability to inhibit the unsaturated bond in the production of unsaturated carboxylic acid ester, regardless of whether it is acidic or basic.
Further, it exhibits an excellent polymerization inhibiting ability as compared with the conventionally used phenothiazine type and hydroquinone type. Also,
Polymerization inhibitors after ester synthesis are:
It can be easily removed by liquid separation.

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[Procedure amendment]

[Submission date] June 18, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

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[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0005

[Correction method] Change

[Correction contents]

That is, the present invention relates to dithiocarbamic acid,
Thiocarbamic acid, and / or a polymerization inhibitor for the unsaturated carboxylic acid ester production process comprising a compound (1) comprising a metal salt, an ammonium salt and / or an amine salt thereof, and in the presence of the compound (1) The present invention relates to a method for producing an unsaturated carboxylic acid ester, which comprises reacting an unsaturated carboxylic acid with a compound having one or more hydroxyl groups in the molecule.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction contents]

In the present invention, examples of the copper salt of the inorganic acid of the compound (2) include copper sulfate, copper nitrate and the like,
Examples of the copper salt of an organic acid include copper acetate, copper maleate and the like.

Claims (5)

[Claims] 1. A polymerization inhibitor for an unsaturated carboxylic acid ester production process comprising dithiocarbamic acid, thiocarbamic acid, and one or more compounds (1) selected from the group consisting of metal salts, ammonium salts or amine salts thereof. . 2. The polymerization inhibitor according to claim 1, wherein the compound (1) is a metal salt of dithiocarbamic acid and / or a metal salt of bisdithiocarbamic acid. 3. The compound (1) is one or more selected from the group consisting of diethanoldithiocarbamic acid copper salt, dimethyldithiocarbamic acid copper salt, diethyldithiocarbamic acid copper salt, dibutyldithiocarbamic acid copper salt and piperazinebisdithiocarbamic acid copper salt. The polymerization inhibitor according to claim 2, which is a compound of 4. The compound (1) according to claim 1 or 2.
And a polymerization inhibitor for an unsaturated carboxylic acid ester production process comprising the copper ion-forming compound (2). 5. The compound (2) is a copper salt of an inorganic acid and / or
Alternatively, the polymerization inhibitor according to claim 4, which is a copper salt of an organic acid.