1,1-dicyanoethyl acetate composition, method for producing 1,1-dicyanoethylene, and 1,1-dicyanoethylene composition

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A 1,1-dicyanoethyl acetate composition with controlled concentrations of acetic acid, acetylcyanide, and α-cyanovinyl acetate addresses yield and discoloration issues in 1,1-dicyanoethylene production, enhancing efficiency and stability.

WO2026121143A1PCT designated stage Publication Date: 2026-06-11KURARAY CO LTD

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Authority / Receiving Office: WO · WO
Patent Type: Applications
Current Assignee / Owner: KURARAY CO LTD
Filing Date: 2025-11-28
Publication Date: 2026-06-11

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Abstract

Provided are: a 1,1-dicyanoethyl acetate composition with which 1,1-dicyanoethylene with suppressed coloration can be produced at a high yield while suppressing the generation of a polymer during the production of the 1,1-dicyanoethylene; and a method for producing 1,1-dicyanoethylene. The 1,1-dicyanoethyl acetate composition comprises: 1,1-dicyanoethyl acetate (A) as a main component; and as a sub-component, at least one compound selected from the group consisting of acetic acid (B1), acetyl cyanide (B2), and α-cyanovinyl acetate (B3). The total concentration of the components (B1)-(B3) is 0.1-30,000 ppm by mass in relation to the mass of the component (A), and the concentration of the acetic acid (B1), the concentration of the acetyl cyanide (B2), and the concentration of the α-cyanovinyl acetate (B3) are each 10,000 ppm by mass or less in relation to the mass of the component (A).

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Description

1,1-Dicyanoethyl acetate composition, method for producing 1,1-dicyanoethylene, and 1,1-dicyanoethylene composition 【0001】 The present invention relates to a 1,1-dicyanoethyl acetate composition, a method for producing 1,1-dicyanoethylene, and a 1,1-dicyanoethylene composition. 【0002】 1,1-dicyanoethylene is a useful compound as a cyanoacrylate adhesive and functional monomer, and various synthesis methods have been investigated in the past. One such method, described in Patent Document 1, involves the thermal decomposition of 1,1-dicyanoethyl acetate to synthesize 1,1-dicyanoethylene. However, this thermal decomposition method requires high temperatures, and because the product, 1,1-dicyanoethylene, is highly reactive, side reactions such as polymerization can lead to low yields. Furthermore, polymers can clog the thermal decomposition piping, reducing productivity. As a measure to improve the stability of 1,1-dicyanoethylene, for example, Patent Document 1 proposes using a strong acid such as sulfuric acid as a stabilizer during or immediately after the synthesis of 1,1-dicyanoethylene. However, strong acids are highly corrosive and can corrode manufacturing equipment and storage containers. This can lead to another problem: discoloration due to metal leaching caused by corrosion can impair the appearance of 1,1-dicyanoethylene. Examples of methods for producing 1,1-dicyanoethyl acetate, a raw material for producing 1,1-dicyanoethylene, include the acetic anhydride method described in Patent Document 2 and the ketene method described in Patent Document 3. 【0003】 U.S. Patent No. 2,663,725, British Patent No. 690,128, and Japanese Unexamined Patent Publication No. 63-122657 【0004】Since strong acids have the above-mentioned problems, there is a need for a novel 1,1-dicyanoethyl acetate composition that can prevent the occurrence of pipe blockage due to polymers during the production of 1,1-dicyanoethylene and produce 1,1-dicyanoethylene with suppressed coloring in a high yield without using strong acids. In view of the above circumstances, an object of the present invention is to provide a 1,1-dicyanoethyl acetate composition and a method for producing 1,1-dicyanoethylene that can produce 1,1-dicyanoethylene with suppressed coloring in a high yield while suppressing the generation of polymers during the production of 1,1-dicyanoethylene. 【0005】 As a result of intensive studies to solve the above problems, the present inventors have found that a 1,1-dicyanoethyl acetate composition containing specific sub-components at concentrations within a specific range can solve the above problems, and have completed the present invention. 【0006】In other words, the present invention is as follows: [1] A 1,1-dicyanoethyl acetate composition comprising 1,1-dicyanoethyl acetate (A) as a main component and at least one compound selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as a secondary component, wherein the total concentration of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 30,000 ppm by mass or less with respect to the mass of 1,1-dicyanoethyl acetate (A), and the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are each 10,000 ppm by mass or less with respect to the mass of 1,1-dicyanoethyl acetate (A). [2] The 1,1-dicyanoethyl acetate composition according to [1] above, comprising one or more compounds selected from the group consisting of acetylcyanide (B2) and α-cyanovinyl acetate (B3) as the auxiliary component. [3] The 1,1-dicyanoethyl acetate composition according to [1] or [2] above, comprising two or more compounds selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as the auxiliary component. [4] The 1,1-dicyanoethyl acetate composition according to [3] above, comprising acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as the auxiliary component. [5] The 1,1-dicyanoethyl acetate composition according to any one of [1] to [4] above, further comprising an organic solvent (C1). [6] A method for producing 1,1-dicyanoethylene, comprising thermally decomposing the 1,1-dicyanoethyl acetate composition described in any one of [1] to [5] above to obtain 1,1-dicyanoethylene (X). [7] A 1,1-dicyanoethylene composition comprising 1,1-dicyanoethylene (X) and α-cyanovinyl acetate (B3), wherein the concentration of α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 10,000 ppm by mass or less, relative to the mass of 1,1-dicyanoethylene (X). [8] The 1,1-dicyanoethylene composition according to [7] above, further comprising at least one selected from the group consisting of acetic acid (B1) and acetylcyanide (B2).[9] The 1,1-dicyanoethylene composition according to [7] or [8], further comprising an organic solvent (C2). 【0007】 The present invention provides a 1,1-dicyanoethyl acetate composition and a method for producing 1,1-dicyanoethylene that can produce 1,1-dicyanoethylene with suppressed discoloration in high yield while suppressing the generation of polymers during the production of 1,1-dicyanoethylene. 【0008】 The following description is based on an example of an embodiment for carrying out the present invention (hereinafter sometimes referred to as "this embodiment"). However, the embodiments shown below are illustrative examples for realizing the technical concept of the present invention, and the present invention is not limited to the following description. In this specification, preferred embodiments are shown, but combinations of two or more individual preferred embodiments are also preferred embodiments. If there are several numerical ranges for matters indicated by numerical ranges, a preferred embodiment can be made by selectively combining their lower and upper limits. In this specification, when a numerical range is described as "XX to YY", it means "XX or more and YY or less". 【0009】 [1,1-Dicyanoethyl Acetate Composition] A 1,1-dicyanoethyl acetate composition according to one or more embodiments of the present invention comprises 1,1-dicyanoethyl acetate (A) as a main component and at least one compound selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as a secondary component, wherein the total concentration of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 30,000 ppm by mass or less with respect to the mass of 1,1-dicyanoethyl acetate (A), and the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are each 10,000 ppm by mass or less with respect to the mass of 1,1-dicyanoethyl acetate (A). 【0010】In this specification, "main component" means a component that is present in more than 50% by mass of the total mass of the composition, excluding diluents such as organic solvents. "Minor component" means a component contained in the composition other than the main component and the diluents. In this specification, a composition containing 1% by mass or more of 1,1-dicyanoethyl acetate (A) is referred to as a "1,1-dicyanoethyl acetate composition". 【0011】 The acetic acid (B1) included as a by-component in the above 1,1-dicyanoethyl acetate composition suppresses the polymerization of 1,1-dicyanoethylene (X) produced by the thermal decomposition of 1,1-dicyanoethyl acetate (A), contributing to improved yield of 1,1-dicyanoethylene (X) and suppression of blockage in the thermal decomposition piping. Although 1,1-dicyanoethylene (X) is a substance with high anionic polymerizability, the presence of a predetermined amount of acetic acid (B1) in the system containing 1,1-dicyanoethylene (X) protonates components such as water that could be the starting point for polymerization, weakening the nucleophilicity of the oxygen atom in the water molecule and suppressing the polymerization of 1,1-dicyanoethylene (X). As a result, it is believed that this leads to improved yield of 1,1-dicyanoethylene (X) and suppression of polymer adhesion to the thermal decomposition piping. Furthermore, compared to using strong acids such as sulfuric acid as polymerization inhibitors, acetic acid (B1) is less corrosive, resulting in less metal contamination from corrosion of manufacturing equipment and storage containers, thus suppressing discoloration of the pyrolysis liquid produced by thermal decomposition. 【0012】 Furthermore, acetylcyanide (B2), which is included as a by-component in the 1,1-dicyanoethyl acetate composition, reacts with water to hydrolyze into acetic acid (B1) and hydrocyanic acid. Therefore, the presence of acetylcyanide (B2) at a predetermined concentration traps water, which is the cause of polymer formation, and produces acetic acid (B1), which suppresses the polymerization of 1,1-dicyanoethylene (X). This contributes to improving the yield of 1,1-dicyanoethylene (X) and suppressing pipe blockage. In addition, the inventors' studies have shown that if the concentration of acetylcyanide (B2) in the 1,1-dicyanoethyl acetate composition is 10,000 ppm by mass or less, the discoloration of the 1,1-dicyanoethyl acetate composition is kept to a level that does not impair its appearance and does not pose a problem. 【0013】 Furthermore, α-cyanovinyl acetate (B3), which is included as a by-component in the 1,1-dicyanoethyl acetate composition, decomposes into ketene and acetylcyanide (B2) under thermal decomposition conditions. Ketene reacts with water to produce acetic acid (B1). Then, as described above, acetylcyanide (B2) reacts with water to hydrolyze into acetic acid (B1) and hydrocyanic acid. For this reason, the presence of α-cyanovinyl acetate (B3) at a predetermined concentration suppresses the polymerization of 1,1-dicyanoethylene (X), contributing to improved yield of 1,1-dicyanoethylene (X) and suppression of pipe blockage. In addition, our own studies have shown that if the concentration of α-cyanovinyl acetate (B3) in the 1,1-dicyanoethyl acetate composition is 10,000 ppm by mass or less, it does not cause discoloration or a decrease in yield that would be practically problematic. 【0014】 Furthermore, the aforementioned Patent Documents 1 to 3 do not describe or suggest that by including at least one compound selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in an appropriate concentration range in 1,1-dicyanoethyl acetate (A), it is possible to obtain 1,1-dicyanoethylene (X) with suppressed discoloration in high yield while suppressing the generation of polymers during the thermal decomposition of 1,1-dicyanoethyl acetate (A). 【0015】 <1,1-Dicyanoethyl Acetate (A)> The 1,1-dicyanoethyl acetate (A), which is included as the main component in the above 1,1-dicyanoethyl acetate composition, is obtained by conventionally known manufacturing methods such as the ketene method or the acetic anhydride method, as described later. Furthermore, it is desirable to use a highly purified 1,1-dicyanoethyl acetate (A) that has been purified so that at least acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are undetectable when used as a raw material for the 1,1-dicyanoethyl acetate composition. 【0016】The content of 1,1-dicyanoethyl acetate (A) in the above 1,1-dicyanoethyl acetate composition is 1% by mass or more relative to the mass of the 1,1-dicyanoethyl acetate composition, and from the viewpoint of preventing the amount of 1,1-dicyanoethyl acetate composition required for the production of 1,1-dicyanoethylene (X) from becoming too large, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. The upper limit of the above content of 1,1-dicyanoethyl acetate (A) is 99.99999% by mass, and from the viewpoint of facilitating thermal decomposition, it is preferably 99.99998% by mass or less, more preferably 99.99997% by mass or less, even more preferably 99.99996% by mass or less, and even more preferably 99.99995% by mass or less. In other words, the content of 1,1-dicyanoethyl acetate (A) in the 1,1-dicyanoethyl acetate composition is 1 to 99.99999% by mass, preferably 5 to 99.99998% by mass, more preferably 10 to 99.99997% by mass, and even more preferably 20 to 99.99995% by mass. The content of 1,1-dicyanoethyl acetate (A) can be determined, for example, by gas chromatography. 【0017】<Acetic acid (B1), acetylcyanide (B2), α-cyanovinyl acetate (B3)> Acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3), which are raw materials for the above 1,1-dicyanoethyl acetate composition, are included in the 1,1-dicyanoethyl acetate composition as minor components. Hereinafter, acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) may be abbreviated as "components (B1) to (B3)". As components (B1) to (B3), commercially available products or commercially available products purified by distillation, etc., can be used. The same applies to α-cyanovinyl acetate (B3) included in the 1,1-dicyanoethylene composition described later, as well as acetic acid (B1) and acetylcyanide (B2) that may be included in the 1,1-dicyanoethylene composition. Furthermore, components (B1) to (B3) can also be components that are by-products when 1,1-dicyanoethyl acetate (A) is synthesized. In this case, commercially available components (B1) to (B3) may be used in combination with any or all of the components (B1) to (B3). 【0018】 The total concentration of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the above 1,1-dicyanoethyl acetate composition is preferably 0.1 ppm to 25,000 ppm by mass, more preferably 0.2 ppm to 10,000 ppm by mass, even more preferably 0.3 ppm to 5,000 ppm by mass, even more preferably 0.4 ppm to 3,000 ppm by mass, and particularly preferably 0.5 ppm to 2,000 ppm by mass, relative to the mass of 1,1-dicyanoethyl acetate (A), from the viewpoint of maintaining a higher level of balance between suppressing the coloration of the pyrolysis liquid obtained by the thermal decomposition of the 1,1-dicyanoethyl acetate composition, suppressing polymer generation, and improving the yield of 1,1-dicyanoethylene (X). 【0019】In the above 1,1-dicyanoethyl acetate composition, the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are preferably 9,000 ppm by mass or less, more preferably 3,000 ppm by mass or less, even more preferably 1,500 ppm by mass or less, and even more preferably 1,000 ppm by mass or less, relative to the mass of 1,1-dicyanoethyl acetate (A), from the viewpoint of making it easier to suppress the coloration of the thermal decomposition liquid to an acceptable level, and from the viewpoint of increasing the content of 1,1-dicyanoethyl acetate (A) in the composition. Regarding the lower limits of the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the above 1,1-dicyanoethyl acetate composition, from the viewpoint of ensuring a balance between suppressing the coloration of the thermal decomposition liquid, reducing the generation of polymers, and improving the yield of 1,1-dicyanoethylene (X), the lower limits are preferably 0.02 ppm by mass or more, more preferably 0.03 ppm by mass or more, and even more preferably 0.05 ppm by mass or more, assuming that the total concentration of components (B1) to (B3) is 0.1 ppm by mass or more. Furthermore, when any of the above components (B1) to (B3) are included individually, the concentration of that individual component is 0.1 ppm by mass or more, preferably 0.2 ppm by mass or more, and more preferably 0.3 ppm by mass or more. In other words, the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the above 1,1-dicyanoethyl acetate composition are preferably 0.02 to 10,000 ppm by mass, and more preferably 0.02 to 9,000 ppm by mass, based on the premise that the total concentration of components (B1) to (B3) is 0.1 ppm by mass or more, relative to the mass of 1,1-dicyanoethyl acetate (A). 【0020】From the viewpoint of making it easier to suppress the polymerization of 1,1-dicyanoethylene (X), the above 1,1-dicyanoethyl acetate composition preferably contains one or more compounds selected from the group consisting of acetylcyanide (B2) and α-cyanovinyl acetate (B3) as the auxiliary component. Both acetylcyanide (B2) and α-cyanovinyl acetate (B3) react with water to produce acetic acid (B1). This traps the water that causes the polymerization of 1,1-dicyanoethylene (X), and the polymerization of 1,1-dicyanoethylene (X) is suppressed by the acetic acid (B1) produced by the reaction with water. 【0021】 From the viewpoint of further suppressing the polymerization of the resulting 1,1-dicyanoethylene (X), further increasing the yield of 1,1-dicyanoethylene (X), and further suppressing the coloration of 1,1-dicyanoethylene (X), it is preferable that the above 1,1-dicyanoethyl acetate composition contains two or more compounds selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as the auxiliary components. 【0022】 From the viewpoint of further suppressing the polymerization of the resulting 1,1-dicyanoethylene (X), further increasing the yield of 1,1-dicyanoethylene (X), and further suppressing the coloration of the thermal decomposition solution, the above 1,1-dicyanoethyl acetate composition preferably contains acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as the auxiliary components. 【0023】 <Organic Solvent (C1)> From the viewpoint of ease of handling during thermal decomposition, it is preferable that the 1,1-dicyanoethyl acetate composition according to one or more embodiments of the present invention further contains an organic solvent (C1) as a diluent. The organic solvent (C1) is preferably a substance that is inert to 1,1-dicyanoethyl acetate (A) and 1,1-dicyanoethylene (X), and is a liquid organic solvent at room temperature. Specific examples include liquid aromatic hydrocarbons or halogen-substituted aromatic hydrocarbons such as benzene, toluene, xylene, trimethylbenzene, monochlorobenzene, dichlorobenzene, and trichlorobenzene. 【0024】When the 1,1-dicyanoethyl acetate composition contains an organic solvent (C1), the content of the organic solvent (C1) in the 1,1-dicyanoethyl acetate composition is preferably 80% by mass or less, more preferably 10% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of avoiding the amount of 1,1-dicyanoethyl acetate composition used in the production of 1,1-dicyanoethylene (X) becoming too large. The lower limit is better if it is as low as possible from the viewpoint of maximizing the amount of 1,1-dicyanoethyl acetate (A) as an active ingredient, and may be, for example, 0.000001% by mass (0.01 ppm by mass) or more. However, from the viewpoint of ease of handling during thermal decomposition, the content of the organic solvent (C1) in the 1,1-dicyanoethyl acetate composition is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. In other words, the content of the organic solvent (C1) in the 1,1-dicyanoethyl acetate composition is preferably 0.000001 to 80% by mass, and more preferably 5 to 80% by mass from the viewpoint of improving ease of handling. 【0025】 <Other Components (Y1)> The 1,1-dicyanoethyl acetate composition may or may not contain other components (Y1) other than the above components (A), (B1) to (B3) and (C1). For example, by-products other than the above components (B1) to (B3) generated when 1,1-dicyanoethyl acetate (A) is synthesized by the ketene method or the acetic anhydride method may be included in the 1,1-dicyanoethyl acetate composition to the extent that they do not affect the effects of the present invention. However, from the viewpoint of suppressing the discoloration of the thermal decomposition liquid, it is preferable that the composition does not contain other components (Y1). 【0026】[Method for Producing 1,1-Dicyanoethyl Acetate Composition] The first method for producing the 1,1-dicyanoethyl acetate composition according to one or more embodiments of the present invention comprises a first step of obtaining unpurified 1,1-dicyanoethyl acetate (A0), a second step of purifying the unpurified 1,1-dicyanoethyl acetate (A0) to obtain high-purity 1,1-dicyanoethyl acetate (A), and a third step of adding a required amount of auxiliary components to 1,1-dicyanoethyl acetate (A) to obtain the 1,1-dicyanoethyl acetate composition. Furthermore, a second method for producing the 1,1-dicyanoethyl acetate composition according to one or more embodiments of the present invention comprises the first step described above, and a fourth step of purifying unpurified 1,1-dicyanoethyl acetate (A0) to obtain high-purity 1,1-dicyanoethyl acetate (A), and adjusting the degree of purification to set the concentration of the auxiliary components within a desired range. 【0027】 In the first step described above, there are no particular restrictions on the method for obtaining unpurified 1,1-dicyanoethyl acetate (A0). For example, the acetic anhydride method using acetic anhydride and hydrogen cyanide, or the ketene method using ketene and hydrogen cyanide, can be used. The acetic anhydride method can be carried out, for example, according to the procedure described in Patent Document 2. The ketene method can be carried out, for example, according to the procedure described in Patent Document 3. 【0028】 In the second step described above, the compound obtained in the first step is purified, for example, by recrystallization to obtain a high-purity 1,1-dicyanoethyl acetate (A) that is purified so that at least acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are undetectable. 【0029】 Then, in the third step described above, the 1,1-dicyanoethyl acetate (A) obtained in the second step is mixed with the required amount of acetic acid (B1), acetylcyanide (B2), or α-cyanovinyl acetate (B3). In this way, a 1,1-dicyanoethyl acetate composition containing the above-mentioned main component and a predetermined concentration of auxiliary components is obtained. There are no particular restrictions on the method of mixing each component, and they can be mixed by known methods. 【0030】 In the fourth step described above, similar to the second step described above, the compound obtained in the first step is purified by recrystallization or the like, and by adjusting the number and degree of purification, a 1,1-dicyanoethyl acetate composition is obtained in which the concentrations of at least acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are within the predetermined range described above. 【0031】 [Uses of 1,1-Dicyanoethyl Acetate Compositions] One or more embodiments of the 1,1-dicyanoethyl acetate composition of the present invention can be used as a raw material for producing 1,1-dicyanoethylene (X). As described above, the 1,1-dicyanoethyl acetate composition contains a predetermined concentration of auxiliary components, which suppresses the coloration of the pyrolysis liquid obtained by pyrolysis of the 1,1-dicyanoethyl acetate composition, and also suppresses the polymerization of the resulting 1,1-dicyanoethylene (X), preventing blockage of pyrolysis piping due to the adhesion of polymers. For this reason, it is a raw material that can efficiently produce 1,1-dicyanoethylene (X) with an excellent appearance in high yield. 【0032】 [1,1-Dicyanoethylene Composition] One or more embodiments of the present invention describe a 1,1-dicyanoethylene composition comprising 1,1-dicyanoethylene (X) and α-cyanovinyl acetate (B3), wherein the concentration of α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 10,000 ppm by mass or less, relative to the mass of 1,1-dicyanoethylene (X). By setting the concentration of α-cyanovinyl acetate (B3) within the above range, a certain level of storage stability is ensured without the use of strong acids, and discoloration of the 1,1-dicyanoethylene composition is prevented. In this specification, a composition containing 1% by mass or more of 1,1-dicyanoethylene (X) is referred to as a "1,1-dicyanoethylene composition". 【0033】<1,1-Dicyanoethylene (X)> 1,1-Dicyanoethylene (X) is produced by the thermal decomposition method of the 1,1-dicyanoethyl acetate composition described above. The concentration of 1,1-dicyanoethylene (X) in the above 1,1-dicyanoethylene composition is 1% by mass or more relative to the mass of the 1,1-dicyanoethylene composition, and from the viewpoint of the amount of active ingredients in the composition, it is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 20% by mass or more. The upper limit of the above concentration of 1,1-dicyanoethylene (X) is 99.99999% by mass, and from the viewpoint of storage stability, it is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, even more preferably 99.0% by mass or less, and even more preferably 95.0% by mass or less. In other words, the above concentration of 1,1-dicyanoethylene (X) in the 1,1-dicyanoethylene composition is 1 to 99.99999% by mass, preferably 5 to 99.9% by mass, more preferably 10 to 99.5% by mass, even more preferably 20 to 99.0% by mass, and even more preferably 20 to 95.0% by mass. The concentration of 1,1-dicyanoethylene (X) can be determined, for example, by gas chromatography. 【0034】 <α-Cyanovinyl Cyanoacetate (B3)> The concentration of α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 10,000 ppm by mass or less, relative to the mass of 1,1-dicyanoethylene (X). From the viewpoint of storage stability and the amount of active ingredients in the composition, it is preferably 0.1 ppm by mass or more and 9,000 ppm by mass or less, more preferably 0.1 ppm by mass or more and 3,000 ppm by mass or less, even more preferably 0.1 ppm by mass or more and 1,500 ppm by mass or less, and even more preferably 0.1 ppm by mass or more and 1,000 ppm by mass or less. The concentration of α-cyanovinyl acetate (B3) in the 1,1-dicyanoethylene composition is determined, for example, by gas chromatography, and specifically measured by the method described in the examples. 【0035】<Acetic acid (B1) and acetylcyanide (B2)> The above 1,1-dicyanoethylene composition may further contain at least one selected from the group consisting of acetic acid (B1) and acetylcyanide (B2) from the viewpoint of ease of manufacture. That is, the above 1,1-dicyanoethylene composition may take any of the following embodiments (i) to (iii). (i) Embodiment comprising 1,1-dicyanoethylene (X), α-cyanovinyl acetate (B3), and acetic acid (B1). (ii) Embodiment comprising 1,1-dicyanoethylene (X), α-cyanovinyl acetate (B3), and acetylcyanide (B2). (iii) Embodiment comprising 1,1-dicyanoethylene (X), α-cyanovinyl acetate (B3), acetic acid (B1), and acetylcyanide (B2). 【0036】 In any of the embodiments (i) to (iii) above, from the viewpoint of storage stability and the amount of active ingredients in the composition, the total concentration of α-cyanovinyl acetate (B3), acetic acid (B1), and acetylcyanide (B2) is preferably 0.1 ppm to 30,000 ppm by mass, more preferably 0.1 ppm to 25,000 ppm by mass, even more preferably 0.2 ppm to 10,000 ppm by mass, even more preferably 0.3 ppm to 5,000 ppm by mass, even more preferably 0.4 ppm to 3,000 ppm by mass, and particularly preferably 0.5 ppm to 2,000 ppm by mass, relative to the mass of 1,1-dicyanoethylene (X). In this case, the concentrations of acetic acid (B1) and acetylcyanide (B2) are preferably 10,000 ppm by mass or less, more preferably 9,000 ppm by mass or less, even more preferably 3,000 ppm by mass or less, even more preferably 1,500 ppm by mass or less, and particularly preferably 1,000 ppm by mass or less, with respect to the mass of 1,1-dicyanoethylene (X). The concentrations of acetic acid (B1) and acetylcyanide (B2) in the 1,1-dicyanoethylene composition are determined, for example, by gas chromatography, and specifically measured by the method described in the examples. 【0037】<Organic Solvent (C2)> The 1,1-dicyanoethylene compositions according to one or more embodiments of the present invention may further contain an organic solvent (C2) as a diluent. Examples of the organic solvent (C2) include aromatic solvents such as toluene and xylene; aliphatic solvents such as hexane and heptane; naphthenic solvents such as cyclohexane; ester solvents such as ethyl acetate; and ether solvents such as tetrahydrofuran and diethyl ether. When the 1,1-dicyanoethylene composition contains an organic solvent (C2), the content of the organic solvent (C2) in the 1,1-dicyanoethylene composition is preferably 80% by mass or less, more preferably 10% by mass or less, and even more preferably 1% by mass or less, from the viewpoint of promoting polymerization of 1,1-dicyanoethylene (X) in the 1,1-dicyanoethylene composition. The lower limit is better as low as possible, for example, it may be 0.000001% by mass (0.01 ppm by mass) or more. In other words, the content of the organic solvent (C2) in the 1,1-dicyanoethylene composition is preferably 0.000001 to 80% by mass. 【0038】 <Brønsted Acid Compound (D)> The 1,1-dicyanoethylene composition may or may not contain Brønsted acid compound (D). When the 1,1-dicyanoethylene composition contains Brønsted acid compound (D), the storage stability of the 1,1-dicyanoethylene composition is improved. When the 1,1-dicyanoethylene composition does not contain Brønsted acid compound (D), corrosion of manufacturing equipment and storage containers is prevented, and consequently, discoloration of the 1,1-dicyanoethylene composition is suppressed. In this specification, acetic acid (B1) is excluded from Brønsted acid compound (D). 【0039】 Examples of the above-mentioned Brønsted acid compound (D) include inorganic acids, carboxylic acids, and organic sulfonic acids, from the viewpoint of storage stability and availability. Among these, it is preferable that it be one or more selected from sulfuric acid, hydrochloric acid, nitric acid, benzenesulfonic acid, p-toluenesulfonic acid, and methanesulfonic acid, and it may also be a compound that reacts with water to produce a compound exhibiting Brønsted acidity, such as sulfur dioxide or phosphorus pentoxide. 【0040】From the viewpoint of ensuring high reactivity while easily improving storage stability, the 1,1-dicyanoethylene composition preferably contains 0.1 ppm by mass or more and less than 15,000 ppm by mass of Brønsted acidic compound (D), more preferably 1 ppm by mass or more and 10,000 ppm by mass or less, and even more preferably 10 ppm by mass or more and 8,000 ppm by mass or less. 【0041】 <Polymerizable monomer (E)> The above 1,1-dicyanoethylene composition may further contain a polymerizable monomer (E). Note that 1,1-dicyanoethylene (X) is removed from the polymerizable monomer (E). The polymerizable monomer (E) is preferably reactive with 1,1-dicyanoethylene (X). The polymerizable monomer (E) may be one type or multiple types. The polymerizable monomer (E) may be a radical polymerizable monomer or an anionic polymerizable monomer. 【0042】 Examples of polymerizable monomers (E) include ethylene, propylene, butadiene, isobutylene, isoprene, 1-hexene, 1-octene, vinyl acetate, vinyl propionate, vinyl butyrate, styrene, α-methylstyrene, p-methylstyrene, alkyl acrylates such as acrylic acid, methacrylic acid, and butyl acrylate, alkyl methacrylates such as methyl methacrylate and dodecyl methacrylate, acrylonitrile, vinyl chloride, vinylidene chloride, vinylidene fluoride, alkyl 2-cyanoacrylate, alkyl 2-cyanopentadienate, and dialkyl methylidenemalonate. Of these, from the viewpoint of excellent reactivity with 1,1-dicyanoethylene (X), it is preferable that the polymerizable monomer (E) is alkyl 2-cyanoacrylate, and it is more preferable that the alkyl 2-cyanoacrylate is ethyl 2-cyanoacrylate. 【0043】<Content of Monomers> The total amount of monomers (1,1-dicyanoethylene (X) and, if necessary, the polymerizable monomer (E)) is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 20% by mass or more, from the viewpoint of having the desired physical properties with respect to the total mass of the 1,1-dicyanoethylene composition. There is no particular limit to the upper limit of the above monomers, and it may be 100% by mass with respect to the total mass of the 1,1-dicyanoethylene composition. However, from the viewpoint of storage stability, it is preferably 99.9% by mass or less, more preferably 99.5% by mass or less, still more preferably 99.0% by mass or less. In other words, the total amount of the above monomers is preferably 1 to 100% by mass with respect to the total mass of the 1,1-dicyanoethylene composition. When the polymerizable monomer (E) is used, the mass ratio of 1,1-dicyanoethylene (X) to the polymerizable monomer (E) is not particularly limited, but may be 99:1 to 1:99, 80:20 to 20:80, or 70:30 to 30:70. 【0044】 <Other Components (Y2)> The above 1,1-dicyanoethylene composition may or may not contain one or more components other than 1,1-dicyanoethylene (X), acetic acid (B1), acetyl cyanide (B2), vinyl α-cyanoacetate (B3), organic solvent (C2), Bronsted acidic compound (D), and polymerizable monomer (E) (other components (Y2)). Examples of the other components (Y2) include phenolic compounds, acid anhydrides, Lewis acidic compounds, thickeners, pigments, and inorganic fillers. The other components (Y2) can be used in a content range that does not impair the desired effects of the present invention. 【0045】The above phenol compounds are compounds other than the above Brønsted acid compound (D). Examples of the above phenol compounds include hydroquinone, p-methylphenol, p-methoxyphenol, and t-butylhydroquinone. Also, 2,6-di-tert-butyl-4-methylphenol, 2,6-di-tert-butylphenol, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2,4-di-tert-butylphenol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis-(4- Ethyl-6-t-butylphenol) (Yoshinox 425), 4,4'-butylidenebis-(6-t-butyl-3-methylphenol) (Yoshinox BB), 2,2'-methylenebis[6-tert-butyl-4-methylphenol] (Smirizer MDP-S), 1,1,3-tris(2-methyl-4-hydroxy-5-tert-butylphenyl)butane (Adekasta AO-30), 4,4'-butylidenebis(6-tert-butyl-m-cresol) (Adekasta) Bu AO-40), Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Adekastab AO-50), 2,2'-dimethyl-2,2'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropane-1,1'-diyl=bis[3-(3-tert-butyl-4-hydroxy-5-methylphenyl)propanoate] (Adekastab AO-80), 1,3,5-trimethyl-2,4,6-tris(3, 5-di-tert-butyl-4-hydroxybenzyl)benzene (Adekastab AO-330), 4,4'-thiobis[3-methyl-6-(tert-butyl)phenol] (Smirizer WX-R), 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 2,4,6-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)mesitylene, 1'-hydroxy[2,2'-ethylidenebis[4,6-bis(1,1-Dimethylpropyl)benzene]]-1-yl (Sumilizer GS), 2-tert-Butyl-4-methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl acrylate (Sumilizer GM), and 2-tert-Butyl-6-methyl-4-{3-[(2,4,8,10-Tetra-tert-butyldibenzo[d,f][1,3,2]dioxaphosphepin-6-yl)oxy]propyl}phenol (Sumilizer GP), and other specific o-substituted phenol compounds are mentioned. 【0046】 [Method for Producing 1,1-Dicyanoethylene (X)] The method for producing 1,1-dicyanoethylene (X) according to one or more embodiments of the present invention includes a step of thermally decomposing any of the above-described 1,1-dicyanoethyl acetate compositions to obtain 1,1-dicyanoethylene (X). The above production method may further include a step of thermally decomposing a 1,1-dicyanoethyl acetate composition to produce unpurified 1,1-dicyanoethylene (X0), and a step of purifying the unpurified 1,1-dicyanoethylene (X0) to obtain high-purity 1,1-dicyanoethylene (X). 【0047】 As the thermal decomposition of the 1,1-dicyanoethyl acetate composition, for example, the method described in Patent Document 1 above is used. Specifically, first, the 1,1-dicyanoethyl acetate composition is evaporated, and this vapor is introduced into a heated pipe for thermal decomposition and thermally decomposed. The hot thermal decomposition product vapor is instantaneously quenched with a large amount of cold (that is, lower temperature than the high-temperature thermal decomposition vapor) fluid or diluent of the thermal decomposition product, or a mixture of both, and the condensed thermal decomposition product is removed from the quenching region. 【0048】 The temperature of the thermal decomposition is preferably 300 to 800°C. From the viewpoint of suppressing excessive decomposition of the diacyl cyanide and polymerization of the monomer and promoting the progress of the thermal decomposition, 500 to 600°C is more preferable. 【0049】Pyrolysis is preferably carried out under atmospheric pressure or a pressure slightly higher than atmospheric pressure (for example, 101 to 120 kPa). By performing pyrolysis under pressure conditions that are above and near atmospheric pressure, there are fewer constraints on the pyrolysis apparatus, it is easier to improve the yield of the product, and it is easier to avoid polymerization of the product, compared to pyrolysis under reduced pressure conditions. 【0050】 Pyrolysis is preferably carried out in the presence of an inert diluent that is gaseous or liquid at room temperature. Using such a diluent, especially one that is liquid at room temperature, eliminates the need for a dryer for the 1,1-dicyanoethyl acetate composition and lowers the melting point of the feed, thus reducing the amount of heat treatment required for the molten 1,1-dicyanoethyl acetate composition in the feed system and lowering the dew point of the pyrolysis product vapor. Furthermore, the use of a diluent lowers the partial pressure of 1,1-dicyanoethylene (X) in the condensed pyrolysis product vapor. 【0051】 Examples of the inert diluent mentioned above include those similar to the organic solvent (C1) described above. Examples of usable inert diluent gases include methane, ethane, propane, nitrogen, hydrogen, helium, and mixtures of these gases. 【0052】 Alternatively, a polymerization inhibitor may be added to the liquid pyrolysis product simultaneously with the condensation process, or at an early stage after the condensation of the pyrolysis vapor, to prevent the polymerization of 1,1-dicyanoethylene (X) from starting. Examples of the polymerization inhibitor include sulfuric acid, halosulfonic acids such as chlorosulfonic acid, sulfonyl chlorides such as toluenesulfonyl chloride and benzenesulfonyl chloride, and sulfur dioxide. From the viewpoint of minimizing discoloration, it is desirable to omit the use of polymerization inhibitors. If a polymerization inhibitor is used, it should be used in an amount that does not cause discoloration, for example, by an amount of 0.05% by mass or less relative to the total mass of 1,1-dicyanoethyl acetate (A) and organic solvent (C1). 【0053】[Method for Producing 1,1-Dicyanoethylene Composition] The 1,1-dicyanoethylene composition can be produced, for example, by a method that includes the steps of purifying the unpurified 1,1-dicyanoethylene (X0) obtained in the above procedure, for example by vacuum distillation, and adding and mixing the required amount of α-cyanovinyl acetate (B3) to the purified 1,1-dicyanoethylene (X). If necessary, the method may further include the step of adding and mixing at least one selected from the group consisting of acetic acid (B1), acetylcyanide (B2), organic solvent (C2), Brønsted acid compound (D), polymerizable monomer (E), and other components (Y2). It is preferable to produce the 1,1-dicyanoethylene composition under a dry atmosphere in order to prevent the polymerization reaction from proceeding due to moisture. There are no particular restrictions on the method of mixing each component, and they can be mixed by known methods. 【0054】 [Uses of 1,1-dicyanoethylene composition] 1,1-dicyanoethylene composition is used in a variety of applications due to its high reactivity. For example, 1,1-dicyanoethylene composition is used as an adhesive (especially instant adhesive), repair agent, reinforcing agent, injection agent, putty, painting agent, sealant, or sealing agent. 1,1-dicyanoethylene composition can be cured by reacting it with a Lewis basic compound. Furthermore, the curability can be enhanced by including the polymerizable monomer (E) mentioned above. 【0055】 The above Lewis basic compound functions as a polymerization catalyst for 1,1-dicyanoethylene (X), or a mixture of 1,1-dicyanoethylene (X) and a polymerizable monomer (E). Examples of Lewis basic compounds include water, alcohols, and alkylamines. Examples of alcohols include methanol, ethanol, and propanol. Examples of alkylamines include tertiary amines such as trimethylamine, triethylamine, tripropylamine, triisopropylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine, and N,N-dimethylisopropylamine. 【0056】The amount of the Lewis basic compound is not particularly limited, but it is preferably 0.001 to 1.0 parts by mass, and more preferably 0.01 to 0.5 parts by mass, per 100 parts by mass of the total of 1,1-dicyanoethylene (X) and polymerizable monomer (E). When the content of the Lewis basic compound is within the above range, 1,1-dicyanoethylene (X), or a mixture of 1,1-dicyanoethylene (X) and polymerizable monomer (E), reacts rapidly. 【0057】 The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these. 【0058】 [Adhesion of Polymers] The presence and amount of solid matter adhering to the outlet end of the pyrolysis piping were checked and evaluated according to the following criteria: A: No solid matter adhering to the outlet end of the pyrolysis piping. B: Solid matter adhering to the outlet end of the pyrolysis piping, with an amount less than 50% of the pipe's cross-sectional area. C: Solid matter adhering to the outlet end of the pyrolysis piping, with an amount greater than 50% of the pipe's cross-sectional area. "A" and "B" were considered pass, and "C" was considered fail. 【0059】 [Coloring of the pyrolysis solution] The coloring of the pyrolysis solution was visually inspected and evaluated according to the following criteria: A: The pyrolysis solution is colorless and transparent. B: The pyrolysis solution is light yellow in color, but at a level that does not impair its appearance. C: The pyrolysis solution is yellow in color, to a level that impairs its appearance. "A" and "B" were considered pass, and "C" was considered fail. 【0060】 [Yield of 1,1-dicyanoethylene (X)] The yield of 1,1-dicyanoethylene (X) was calculated using the following formula (1): Yield of 1,1-dicyanoethylene (X) = [Concentration of 1,1-dicyanoethylene (X) in the pyrolysis solution (mass%) × Mass of pyrolysis solution (g) / 78.07] ÷ [Mass of feed of 1,1-dicyanoethyl acetate (A) (g) / 138.12] ... Formula (1) 【0061】[Concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3), and concentration of 1,1-dicyanoethylene (X)] For measuring the concentrations of components (B1) to (B3), the 1,1-dicyanoethyl acetate composition was first pretreated by vaporizing the composition and absorbing it into a solvent using the following method. A 1 L four-necked flask was fitted with a stirrer, a thermometer, a glass tube (6 mm inner diameter) with one end positioned in the gas phase of the flask and the other end connected to a trap tube, and a glass tube (6 mm inner diameter) gas introduction tube that reached near the bottom of the flask. 300 g of the 1,1-dicyanoethyl acetate composition was placed in this four-necked flask and heated and stirred using an oil bath. Nitrogen gas was introduced at a rate of 100 mL / min from the glass tube near the bottom of the flask while maintaining the temperature at 160-165°C. The vaporized components were absorbed by introducing them into a trap tube filled with 5 mL of methyl acetate and cooled to -40°C to obtain an absorbent solution. The concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the absorbent solution, and the concentrations of 1,1-dicyanoethylene (X), acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the 1,1-dicyanoethylene composition that had not undergone the above pretreatment, were quantified using gas chromatography (GC-2014AF / SPL, Shimadzu Corporation) with a calibration curve prepared from known concentrations of acetic acid (B1), acetylcyanide (B2), α-cyanovinyl acetate (B3), and 1,1-dicyanoethylene (X).• Column: InertCap for Amines (30m x 0.32mm) • Detector: FID • Column temperature: 0°C x 1 min → 5°C / min → 90°C (no hold) → 50°C / min → 260°C x 6 min (Total 16.4 min) • Vaporization chamber temperature: 150°C • Detector temperature: 270°C • Carrier gas: He • Pressure: 97.0 kPa • Total flow rate: 36.5 mL / min • Column flow rate: 3.04 ml / min • Linear velocity: 46.6 cm / sec • Purge flow rate: 3.0 mL / min • Split ratio: 1:10 • Injection volume: 0.5 μL Furthermore, the detection limit for the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the 1,1-dicyanoethyl acetate composition using the above measurement method is 0.03 ppm by mass. The detection limit for the concentrations of 1,1-dicyanoethylene (X), acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) in the 1,1-dicyanoethylene composition is 3 ppm by mass. 【0062】 [Storage Stability of 1,1-Dicyanoethylene Composition] The 1,1-dicyanoethylene composition was stored at 25°C under a nitrogen atmosphere for one week. After storage, the presence or absence of precipitates and hardening in the 1,1-dicyanoethylene composition was visually inspected and evaluated according to the following criteria: A: No precipitation or hardening. B: No hardening, and a small amount of precipitation, but at a level that does not affect practical use. C: Hardening present. "A" and "B" were considered acceptable, and "C" was considered unacceptable. 【0063】 [Coloring of 1,1-dicyanoethylene composition] The coloring of the 1,1-dicyanoethylene composition was visually confirmed and evaluated according to the following criteria: A: Colorless and transparent. B: Slightly yellowish, but at a level that does not impair the appearance. C: Slightly yellowish, at a level that impairs the appearance. "A" was considered a pass, and "B" and "C" were considered a fail. 【0064】[Preparation of 1,1-Dicyanoethyl Acetate (A)] <Synthesis of unpurified 1,1-Dicyanoethyl Acetate (A0)> A stirrer, thermometer, reflux condenser, and a glass tube (6 mm inner diameter) gas inlet tube that reached near the bottom of the flask were attached to a 2 L four-necked flask. 365 g of methyl acetate and 5.4 g of triethanolamine were added to this four-necked flask and stirred. After cooling the flask to 10°C, 181 g of hydrogen cyanide was added. While maintaining the temperature of the reaction solution at 20-25°C, 270 g of ketene gas was introduced over approximately 6 hours. After the reaction, 340 g of methyl acetate and 10.6 g of unreacted hydrogen cyanide were recovered by atmospheric distillation. The residue was subjected to vacuum distillation using a packed column with a diameter of 18 mm and a height of 300 mm, with a helical glass packing with a diameter of 5 mm and a length of 10 mm packed into the packed section, to obtain 376 g of unpurified 1,1-dicyanoethyl acetate (A0). 【0065】 <Purification of 1,1-dicyanoethyl acetate (A)> 100 g of the unpurified 1,1-dicyanoethyl acetate (A0) was added to 200 g of ethanol, heated to 70°C to dissolve, and the resulting solution was cooled to 0°C for recrystallization. This process of filtration was repeated multiple times to obtain 79 g of 1,1-dicyanoethyl acetate (A), a white solid purified to the point where acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) were undetectable. 【0066】 [Preparation of 1,1-dicyanoethyl acetate compositions (Examples 1-15, Comparative Examples 1-6)] The 1,1-dicyanoethyl acetate compositions of Examples 1-15 and Comparative Examples 1-6 were prepared by adding acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) to the purified 1,1-dicyanoethyl acetate (A) described above in the proportions shown in Tables 1-1 and 1-2 and mixing. In Comparative Example 6, the above purification operation was not performed, nor were components (B1) to (B3) added. The unpurified 1,1-dicyanoethyl acetate (A0) obtained by the above procedure was directly subjected to the following thermal decomposition operation. 【0067】[Thermal Decomposition of 1,1-Dicyanoethyl Acetate Compositions] The entire volume of the 1,1-dicyanoethyl acetate compositions from Examples 1 to 15 and Comparative Examples 1 to 6 was collected, and 1 part by mass of the 1,1-dicyanoethyl acetate composition was dissolved in 0.5 parts by mass of monochlorobenzene. The resulting solution was then fed at 23.5 kg / hr into a stainless steel thermal decomposition tube (tube length approximately 2 m, outer diameter approximately 6.35 mm, wall thickness approximately 1.00 mm) under atmospheric pressure, and thermal decomposition was carried out at 530°C. The resulting decomposition gas was absorbed into 10 parts by mass of monochlorobenzene to obtain a thermal decomposition solution. However, in Comparative Example 5, 10 parts by mass of monochlorobenzene containing 100 ppm by mass of sulfuric acid was used as the absorbent. 【0068】 The measurement and evaluation results, along with the concentrations of each component contained in the 1,1-dicyanoethyl acetate composition, are shown in Tables 1-1 and 1-2. 【0069】【0070】 The meanings of the abbreviations in Tables 1-1 and 1-2 above are as follows: ・DAC: 1,1-dicyanoethyl acetate (A) ・AcOH: Acetic acid (B1) ・AcCN: Acetyl cyanide (B2) ・αCNVAc: α-cyanovinyl acetate (B3) ・DCE: 1,1-dicyanoethylene (X) ・N.D.: Not detected In addition, "-" in the "Content in absorbent solution (monochlorobenzene)" column of Tables 1-1 and 1-2 above means that the corresponding component was not included. 【0071】 As shown in Tables 1-1 and 1-2, the 1,1-dicyanoethyl acetate compositions of Examples 1 to 15, in which the total concentration of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) was 0.1 ppm by mass or more and 30,000 ppm by mass or less, and the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) were each 10,000 ppm by mass or less, had a yield of 1,1-dicyanoethylene (X) of 72% or more, and the evaluation of polymer adhesion and the coloration of the thermal decomposition liquid was "A" or "B". 【0072】On the other hand, the composition of Comparative Example 1, in which acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) were not detected, received an "A" rating for the coloration of the pyrolysis solution, but a "C" rating for polymer adhesion, and the yield of 1,1-dicyanoethylene (X) was 63%, which was significantly lower than that of the example composition. Furthermore, the compositions of Comparative Examples 2 to 4, in which the concentration of any one of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) exceeded 10,000 ppm by mass, received a "C" rating for polymer adhesion or the coloration of the pyrolysis solution. In addition, the compositions of Comparative Examples 2 and 4 had a yield of 1,1-dicyanoethylene (X) of 52% or less, which was significantly lower than that of the example composition. Furthermore, the composition of Comparative Example 5, which contained sulfuric acid and in which acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) were undetectable, received an "A" rating for polymer adhesion and a yield of 1,1-dicyanoethylene (X) of 70%, but received a "C" rating for the coloration of the pyrolysis solution. In addition, the composition of Comparative Example 6, which underwent distillation but not recrystallization, had a concentration of α-cyanovinyl acetate exceeding 10,000 ppm by mass, a yield of 1,1-dicyanoethylene (X) significantly lower than that of the examples, and received a "C" rating for the coloration of the pyrolysis solution. 【0073】 [Preparation of 1,1-dicyanoethylene composition (Examples 16-27, Comparative Examples 7-9)] The unpurified 1,1-dicyanoethylene (X0) obtained in Example 4 was purified by vacuum distillation (480 Pa) until acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) were undetectable, thereby obtaining purified 1,1-dicyanoethylene (X). Acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) were added to and mixed with the purified 1,1-dicyanoethylene (X) at concentrations shown in Tables 2-1 and 2-2 relative to the mass of 1,1-dicyanoethylene (X) to prepare a 1,1-dicyanoethylene composition. 【0074】 The measurement and evaluation results, along with the concentrations of each component in the 1,1-dicyanoethylene composition, are shown in Tables 2-1 and 2-2. 【0075】【0076】【0077】 The meanings of the abbreviations in Tables 2-1 and 2-2 above are as follows: • AcOH: Acetic acid (B1) • AcCN: Acetyl cyanide (B2) • αCNVAc: α-Vinyl cyanoacetate (B3) 【0078】 The 1,1-dicyanoethylene compositions of Examples 16 to 27 demonstrated good storage stability and exhibited the effect of suppressing discoloration of the 1,1-dicyanoethylene compositions. On the other hand, the compositions of Comparative Examples 7 to 9, in which α-cyanovinyl acetate (B3) was not detected, all exhibited poor storage stability. 【0079】 By using the 1,1-dicyanoethyl acetate composition of the present invention, the generation of polymers during the production of 1,1-dicyanoethylene (X) is reduced, while 1,1-dicyanoethylene (X) with suppressed discoloration is produced in high yield. Therefore, it can be used as a raw material for the production of 1,1-dicyanoethylene (X) that has high productivity and a good appearance, and can be obtained with high productivity and high yield. This application is based on Japanese Patent Application No. 2024-211991, filed on December 5, 2024, which is incorporated by reference in its entirety.

Claims

1. A 1,1-dicyanoethyl acetate composition comprising 1,1-dicyanoethyl acetate (A) as the main component and at least one compound selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as a secondary component, wherein the total concentration of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 30,000 ppm by mass or less with respect to the mass of 1,1-dicyanoethyl acetate (A), and the concentrations of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) are each 10,000 ppm by mass or less with respect to the mass of 1,1-dicyanoethyl acetate (A).

2. The 1,1-dicyanoethyl acetate composition according to claim 1, comprising one or more compounds selected from the group consisting of acetylcyanide (B2) and α-cyanovinyl acetate (B3) as the aforementioned minor component.

3. The 1,1-dicyanoethyl acetate composition according to claim 1, comprising two or more compounds selected from the group consisting of acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as the aforementioned auxiliary components.

4. The 1,1-dicyanoethyl acetate composition according to claim 3, comprising acetic acid (B1), acetylcyanide (B2), and α-cyanovinyl acetate (B3) as the aforementioned auxiliary components.

5. The 1,1-dicyanoethyl acetate composition according to claim 1, further comprising an organic solvent (C1).

6. A method for producing 1,1-dicyanoethylene, comprising thermally decomposing a 1,1-dicyanoethyl acetate composition according to any one of claims 1 to 5 to obtain 1,1-dicyanoethylene (X).

7. A 1,1-dicyanoethylene composition comprising 1,1-dicyanoethylene (X) and α-cyanovinyl acetate (B3), wherein the concentration of α-cyanovinyl acetate (B3) is 0.1 ppm by mass or more and 10,000 ppm by mass or less, relative to the mass of 1,1-dicyanoethylene (X).

8. The 1,1-dicyanoethylene composition according to claim 7, further comprising at least one selected from the group consisting of acetic acid (B1) and acetylcyanide (B2).

9. The 1,1-dicyanoethylene composition according to claim 7, further comprising an organic solvent (C2).