Polyindigo monomer, method for producing polyindigo monomer, and method for producing polyindigo

Abstract

To provide a polyindigo monomer, a method for producing the polyindigo monomer, and a method for producing polyindigo, enabling efficient formation of polyindigo.SOLUTION: The polyindigo monomer is represented by the following chemical formula (1), where Ar represents an aryl group and Ac represents an acetyl group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyindigo monomer capable of producing polyindigo, a high-strength fiber, a method for producing the polyindigo monomer, and a method for producing polyindigo. [Background technology]

[0002] Carbon fiber reinforced plastics (CFRP) are lightweight and extremely strong, making them widely used in aircraft, automobiles, industrial equipment, sporting goods, and more. However, carbon fiber is difficult to burn and cannot be burned in a normal incinerator, and CFRP, the reinforced plastic made from carbon fiber, cannot be incinerated either. Furthermore, because of its extreme strength, it is difficult to shred, and it is often disposed of in landfills in its original form, meaning that CFRP products place a high burden on the environment. For this reason, there has been active research into ways to recycle CFRP.

[0003] There has been active research into recovering and reusing plastic products after use, and methods that have been put into practical use include thermal recycling, in which plastic is burned and used as fuel, material recycling, in which plastic is remelted and reprocessed into sheets or fibers, and chemical recycling, in which plastic is chemically treated to break it down into monomers and then polymerized again for reuse.Polyethylene terephthalate (PET), which is widely used in everyday society as PET bottles and fibers, has a high recycling rate, and research is underway into chemical recycling, which does not deteriorate its physical properties during recycling.

[0004] On the other hand, polyindigo is expected to have high strength and a high modulus of elasticity, and if used in fiber-reinforced plastics (FRP), although its compressive performance falls short of that of CFRP, it could potentially be a material with tensile strength equivalent to that of CFRP and with impact resistance exceeding that of CFRP. Despite possessing such excellent physical properties, it is easily water-soluble as disclosed in Patent Document 1, making it possible to recover polyindigo from discarded FRP that uses polyindigo by adding water, and the recovered aqueous solution can be used as is as a spinning solution to regenerate polyindigo fiber.

[0005] Patent Document 2 discloses two methods for synthesizing polyindigo: one using paraphenylenediamine as a starting material, and the other using 2,5-dichloroterephthalic acid as a starting material. The synthetic route using paraphenylenediamine as a starting material is shown in the following chemical reaction formula (A), and the synthetic route using 2,5-dichloroterephthalic acid as a starting material is shown in the following chemical reaction formula (B).

[0006] [ka]

[0007] [ka]

[0008] Furthermore, Patent Document 3 discloses a method for producing a diglycyl terephthalic acid compound, which is a synthetic intermediate for polyindigo, using a cyclohexanediene compound as a starting material. The synthetic route disclosed in Patent Document 3 is shown in the following chemical reaction formula (C).

[0009] [ka]

[0010] Furthermore, Patent Document 4 discloses a method for synthesizing polyindigo by polymerizing a predetermined monomer in an acidic solvent. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-162193 [Patent Document 2] U.S. Patent No. 3,414,545 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-127321 [Patent Document 4] Japanese Patent Application Laid-Open No. 2008-56818 Summary of the Invention [Problem to be solved by the invention]

[0012] However, in the method described in Patent Document 2, which uses paraphenylenediamine as a starting material (the above chemical reaction formula (A)), a substance having two or more acetate groups on the amino group is produced as a by-product in the step of introducing acetate groups into phenylenediamine. This substance has similar properties to the target substance, making it difficult to isolate the target substance. Furthermore, this method results in the polyindigo containing a large amount of impurities.

[0013] Furthermore, among the methods described in Patent Document 2, the method using 2,5-dichloroterephthalic acid as a starting material (the above chemical reaction formula (B)) has the problem that the product becomes tarry in the ring-closure reaction step of diglycyl terephthalic acid, making it impossible to obtain the desired ring-closed substance, and there is also the risk that the diglycyl terephthalic acid cannot be sufficiently purified because the structure of the impurities is similar to that of diglycyl terephthalic acid.

[0014] The synthesis method described in Patent Document 3 (chemical reaction formula (C) above) also has the problem that the acetyl group protecting the secondary amine is not removed under basic conditions during the hydrolysis of tetraacetylbenzodiketobispyrrole. There is also the problem of a ring-opening reaction of the five-membered ring occurring. In the method disclosed in Patent Document 4, the acetyl group is removed by performing hydrolysis under sulfuric acid acidic conditions, but there is a problem of sulfonation occurring as a side reaction. Thus, it is difficult to efficiently produce polyindigo using existing synthesis methods.

[0015] In view of the above circumstances, an object of the present invention is to provide a polyindigo monomer capable of efficiently producing polyindigo, a method for producing a polyindigo monomer, and a method for producing polyindigo. [Means for solving the problem]

[0016] A polyindigo monomer according to one embodiment of the present invention is represented by the following chemical formula (1).

[0017] [ka] [In the formula, Ar represents an aryl group, and Ac represents an acetyl group]

[0018] the aryl group is any one of a phenyl group, a biphenyl group, a naphthyl group, a phenyl group modified with a substituent, a biphenyl group modified with a substituent, and a naphthyl group modified with a substituent; The substituent may be at least one of a halogeno group and an alkyl group.

[0019] The polyindigo monomer may be represented by the following chemical formula (2):

[0020] [ka] [In the formula, R 1 , R 2 , R 3 , R 4, R 5 and R 6 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

[0021] The polyindigo monomer may be represented by the following chemical formula (3):

[0022] [ka] [In the formula, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

[0023] The polyindigo monomer may be represented by the following chemical formula (4): [ka] [In the formula, R 1 and R 2 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

[0024] The polyindigo monomer may be represented by the following chemical formula (5):

[0025] [ka] [In the formula, R 1 and R 2 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

[0026] In a method for producing a polyindigo monomer according to one embodiment of the present invention, a substance represented by the following chemical formula (6) is produced by the Leimgruber-Batcho reaction. An acetoxy group is added to the carbon atom at the 3rd position of the pyrrole ring of the substance.

[0027] [ka] [wherein Ar represents an aryl group]

[0028] In the step of adding an acetoxy group, a halogeno group may be bonded to the carbon atom at the 3-position of the pyrrole ring of the substance, and then silver acetate may be supplied to substitute the halogeno group with an acetoxy group.

[0029] In the step of adding an acetoxy group, a benzyl group may be bonded to the nitrogen atom of the pyrrole ring of the substance, and then (diacetoxyiodo)benzene may be supplied to bond an acetoxy group to the carbon atom at position 3 of the pyrrole ring, and then the benzyl group may be removed.

[0030] In the step of producing a substance represented by the above chemical formula (6), A substance represented by the following chemical formula (7) may be produced by the Reingruber-Bachcho reaction using 3,3'-dimethyl-4,4'-dinitrobiphenyl or a derivative thereof as a starting material.

[0031] [ka] [In the formula, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

[0032] In the step of producing a substance represented by the above chemical formula (6), A substance represented by the following chemical formula (8) may be produced by the Reingruber-Bachcho reaction using 4,4'-dimethyl-3,3'-dinitrobiphenyl or a derivative thereof as a starting material.

[0033] [ka] [In the formula, R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

[0034] In the step of producing a substance represented by the above chemical formula (6), A substance represented by the following chemical formula (9) may be produced by the Reingruber-Bachcho reaction using 2,5-dinitro-p-xylene or a derivative thereof as a starting material.

[0035] [ka] [In the formula, R 1 and R 2 represents hydrogen, a halogen group, or an alkyl group.

[0036] In the step of producing a substance represented by the above chemical formula (6), A substance represented by the following chemical formula (10) may be produced by the Reingruber-Bachcho reaction using 2,4-dinitro-m-xylene or a derivative thereof as a starting material.

[0037] [ka] [In the formula, R 1 and R 2 represents hydrogen, a halogen group, or an alkyl group.

[0038] A method for producing a polyindigo monomer according to one embodiment of the present invention includes the steps of: The acetyl group is eliminated from a polyindigo monomer represented by the following chemical formula (1): The polyindigo monomer from which the acetyl group has been removed is polymerized to produce polyindigo.

[0039] [ka] [In the formula, Ar represents an aryl group, and Ac represents an acetyl group] [Effects of the Invention]

[0040] According to the present invention, it is possible to provide a polyindigo monomer capable of efficiently producing polyindigo, a method for producing a polyindigo monomer, and a method for producing polyindigo. DETAILED DESCRIPTION OF THE INVENTION

[0041] A method for producing polyindigo according to an embodiment of the present invention will be described. In the method for producing polyindigo according to this embodiment, polyindigo is produced by polymerizing the polyindigo monomers shown below.

[0042] [Polyindigo Monomer Structure] The polyindigo monomer according to this embodiment is a substance represented by the following chemical formula (1). [ka]

[0043] In the formula, Ar represents an aryl group, and Ac represents an acetyl group. The aryl group is any one of a phenyl group, a biphenyl group, a naphthyl group, a phenyl group modified with a substituent, a biphenyl group modified with a substituent, and a naphthyl group modified with a substituent. The substituent is at least one of a halogeno group and an alkyl group. This also applies to the following chemical formulas.

[0044] The substance represented by chemical formula (1) may have a trans isomer or a cis isomer depending on the structure of the aryl group (Ar). In this case, the polyindigo monomer according to this embodiment may be either or both of the trans isomer and the cis isomer.

[0045] In other words, the polyindigo monomer according to this embodiment has two pyrrole rings bonded to an aryl group (Ar), and an acetoxy group (-OAc) is bonded to the carbon atom at the third position of each pyrrole ring. The aryl group is, as described above, any of a phenyl group and the like.

[0046] Specifically, the polyindigo monomer according to this embodiment can be any of the substances represented by the following chemical formulas (2) to (5).

[0047] [ka]

[0048] [ka] In the chemical formulas (2) and (3), R 1 , R 2 , R 3 , R 4 , R 5 and R 6 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group. The alkyl group is any of a methyl group, an ethyl group, a propyl group, an isopropyl group, and a tert-butyl group. This is the same in each of the following chemical formulas.

[0049] [ka]

[0050] [ka] In addition, in chemical formulas (4) and (5), R 1 and R 2 represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group. The alkyl group is any of a methyl group, an ethyl group, a propyl group, an isopropyl group, and a tert-butyl group. This is the same in each of the following chemical formulas. In chemical formula (4), R 1 and R 2When R is hydrogen, the substance is called 3,7-diacetoxybenzo[1,2-b:4,5-b]dipyrrole. 1 and R 2 When is hydrogen, the substance is called 3,5-diacetoxybenzo[1,2-b:5,4-b]dipyrrole.

[0051] As shown in chemical formulas (1) to (5), the polyindigo monomer according to this embodiment has two pyrrole rings, each of which has an acetoxy group (-OAc) bonded to the carbon atom at the 3-position, while the nitrogen atom (N) of each pyrrole ring does not have an acetyl group (-Ac) bonded to it.

[0052] By adopting such a structure, it becomes possible to easily remove the acetyl group in the acetoxy group when polymerizing the polyindigo monomer, as described below. If an acetyl group is bonded to the nitrogen atom of the pyrrole ring, the bond is an amide bond, which cannot be easily removed, and treatment with a strong base or strong acid is required. In this case, a ring-opening reaction or sulfonation of the pyrrole ring may occur, which may result in a decrease in yield or the inclusion of by-products. In the polyindigo monomer according to this embodiment, an acetyl group is not bonded to the nitrogen atom of each pyrrole ring, and therefore such treatment is not necessary.

[0053] [Method of producing polyindigo monomer] The method for producing the polyindigo monomer according to this embodiment involves causing a Leimgruber-Batcho reaction with a starting material having two nitro groups, as shown in the following chemical reaction formula (6), to produce a substance having two pyrrole rings.

[0054] [ka]

[0055] The Leingruber-Bachcho reaction involves carbon-adding the starting material (Step A) and then reducing the nitro group to an amine (Step B) to form a pyrrole ring. Carbon-adding (Step A) can be carried out using a dialkylformamide dialkyl acetal, such as dimethylformamide dimethyl acetal or diethylformamide diethyl acetal.

[0056] The reduction (Step B) may be carried out by any method capable of reducing a nitro group to an amine, and various reduction methods can be used, such as a method using hydrazine with iron chloride hexahydrate as a catalyst, a method using Raney-Nickel, or a method using palladium-activated carbon as a catalyst and blowing hydrogen into the reaction product.

[0057] The compounds produced by this Reingruber-Bachcho reaction are hereafter referred to as "dipyrrole compounds." Chemical reaction formula (6) shows the method for producing the trans isomer, but as shown in the following chemical reaction formula (7), depending on the position of the nitro group in the starting material, cis isomers of dipyrrole compounds can also be produced.

[0058] [ka]

[0059] Next, as shown in the following chemical reaction formula (8), an acetoxy group (-OAc) is added to the carbon atom at the 3-position of the pyrrole ring of the dipyrrole compound (step C), thereby producing the polyindigo monomer of this embodiment.

[0060] [ka]

[0061] Chemical reaction formula (8) shows how the trans isomer is produced, but as shown in the following chemical reaction formula (9), depending on the position of the nitrogen atom that constitutes the pyrrole ring, a cis isomer can be produced.

[0062] [ka]

[0063] Specifically, the acetoxylation (step C) can be carried out using one of the following two methods. Hereinafter, these methods will be referred to as "acetoxylation method 1" and "acetoxylation method 2."

[0064] Acetoxylation method 1 is shown in the following chemical reaction scheme (10). In this method, a dipyrrole compound is prepared by the Reingruber-Bachcho reaction, and a halogeno group (-X) is attached to the carbon atom at the 3-position of the pyrrole ring of this compound (Step C1a). The halogen that forms the halogeno group is iodine (I) or bromine (Br).

[0065] [ka] Subsequently, silver acetate (AcOAg) is supplied to this substance, and the halogeno group is replaced with an acetoxy group (-OAc) (step C1b). This allows the production of the polyindigo monomer according to this embodiment. Similarly, for the cis-isomer, a halogeno group (-X) is bonded to the carbon atom at the third position of the pyrrole ring of the dipyrrole compound, and the resulting carbon atom is replaced with an acetoxy group (-OAc), thereby producing the polyindigo monomer according to this embodiment.

[0066] Acetoxylation Method 2 is shown in the following chemical reaction scheme (11). In this method, a dipyrrole compound is prepared by the Reingruber-Bachcho reaction, and a benzyl group (-Bn) is attached to the nitrogen atom (N) of the pyrrole ring of this compound (Step C2a). The benzyl group can be attached to the dipyrrole compound by adding a halogenated methylbenzene such as bromomethylbenzene to the dipyrrole compound together with a strong base.

[0067] [ka]

[0068] Next, (diacetoxyiodo)benzene (DAIB) is supplied to this substance, and an acetoxy group (-OAc) is bonded to the carbon atom at position 3 of the pyrrole ring (Step C2b). Furthermore, this substance is reduced to remove the benzyl group (Step C2c). This allows the production of the polyindigo monomer of this embodiment. Similarly, for the cis isomer, a benzyl group (-Bn) is bonded to the nitrogen atom (N) of the pyrrole ring of the dipyrrole compound, and then an acetoxy group (-OAc) is bonded to the carbon atom at position 3 of the pyrrole ring, and the benzyl group is removed, allowing the production of the polyindigo monomer of this embodiment.

[0069] In addition to the above-mentioned acetoxylation method 1 and acetoxylation method 2, any method capable of adding acetoxylation to the carbon atom at the 3-position of the pyrrole ring of the dipyrrole compound can be used for the acetoxylation (step C).

[0070] As described above, in this embodiment, a polyindigo monomer can be produced by steps A to C. The produced polyindigo monomer (see chemical reaction formulas (8) and (9)) has a structure in which an acetoxy group (-OAc) is bonded to the carbon atom at the 3-position of each pyrrole ring, and an acetyl group (-Ac) is not bonded to the nitrogen atom (N) of each pyrrole ring.

[0071] Specific methods for producing a polyindigo monomer will be described below. The method for producing a polyindigo monomer includes the above-mentioned steps A to C. Of these, the method in which step C is acetoxylation method 1 will be referred to as "production method 1," and the method in which step C is acetoxylation method 2 will be referred to as "production method 2."

[0072] (Example 1 of Manufacturing Method 1) The following chemical reaction scheme (12) shows the production of polyindigo monomer using Production Method 1, starting from 3,3'-dimethyl-4,4'-dinitrobiphenyl (or its derivatives). The production method for 3,3'-dimethyl-4,4'-dinitrobiphenyl (or its derivatives) will be described later. As shown in chemical reaction scheme (12), 3,3'-dimethyl-4,4'-dinitrobiphenyl (or its derivatives) undergoes the Reingruber-Bachcho reaction. Specifically, dimethylformamide dimethyl acetal is added in a DMF (dimethylformamide) solvent to increase the carbon number (Step A). ​​Subsequently, this material is ring-closed by the action of hydrazine (NH2NH2) using iron chloride hexahydrate (FeCl3·6H2O) as a catalyst (Step B), producing a pyrrole ring.

[0073] [ka]

[0074] Next, the product of step B is dissolved in a water / methanol mixed solution (MeOH / HO), and potassium iodide (KI), iodine (I), and sodium hydroxide (NaOH) are added for iodination (step C1a). At this time, the iodine atom (I) is bonded to the carbon atom at position 3 of the pyrrole ring. After vacuum drying, the product is dissolved in acetic acid (AcOH), and silver acetate (AcOAg) is added (step C1b). As a result, the iodine bonded to the carbon atom at position 3 of the pyrrole ring is replaced with an acetoxy group (-OAc). Sufficient dehydration by the vacuum drying improves the yield. In this way, the polyindigo monomer of this embodiment is produced. Bromine may be used instead of iodine in step C1a. Furthermore, other reactants, catalysts, and solvent catalysts that produce the above-mentioned products may be used in steps A to C1b.

[0075] (Example 2 of Manufacturing Method 1) The following chemical reaction scheme (13) shows the production of polyindigo monomer using Production Method 1, starting from 4,4'-dimethyl-3,3'-dinitrobiphenyl (or its derivative). The production method for 4,4'-dimethyl-3,3'-dinitrobiphenyl (or its derivative) will be described later. As shown in chemical reaction scheme (13), 4,4'-dimethyl-3,3'-dinitrobiphenyl (or its derivative) undergoes the Reingruber-Bachcho reaction. Specifically, dimethylformamide dimethyl acetal is added in a DMF (dimethylformamide) solvent to increase the carbon number (Step A). ​​Subsequently, this material is ring-closed by the action of hydrazine (NH2NH2) using iron chloride hexahydrate (FeCl3·6H2O) as a catalyst (Step B), producing a pyrrole ring.

[0076] [ka]

[0077] Next, the product of step B is dissolved in a water / methanol mixed solution (MeOH / HO), and potassium iodide (KI), iodine (I), and sodium hydroxide (NaOH) are added for iodination (step C1a). At this time, the iodine atom (I) is bonded to the carbon atom at position 3 of the pyrrole ring. After vacuum drying, the product is dissolved in acetic acid (AcOH), and silver acetate (AcOAg) is added (step C1b). As a result, the iodine bonded to the carbon atom at position 3 of the pyrrole ring is replaced with an acetoxy group (-OAc). Sufficient dehydration by the vacuum drying improves the yield. In this way, the polyindigo monomer of this embodiment is produced. Bromine may be used instead of iodine in step C1a. Furthermore, other reactants, catalysts, and solvent catalysts that produce the above-mentioned products may be used in steps A to C1b.

[0078] (Example 3 of Manufacturing Method 1) The following chemical reaction formula (14) shows a method for producing a polyindigo monomer by Production Method 1 using 2,5-dinitro-p-xylene (or a derivative thereof) as a starting material.

[0079] [ka]

[0080] As shown in this scheme, the Reingruber-Bachcho reaction of 2,5-dinitro-p-xylene (or its derivatives) produces benzo[1,2-b:4,5-b]dipyrrole (and derivatives). Specifically, dimethylformamide dimethyl acetal is added in DMF (dimethylformamide) solvent to increase the carbon number (Step A). ​​Next, this substance is ring-closed by the action of hydrazine using iron chloride hexahydrate (FeCl3·6H2O) as a catalyst (Step B), producing the pyrrole ring.

[0081] Next, the benzo[1,2-b:4,5-b]dipyrrole (and derivatives) produced in step B is dissolved in a water / methanol mixture (MeOH / HO), and potassium iodide (KI), iodine (I), and sodium hydroxide (NaOH) are added for iodination (step C1a). The iodine atom (I) is bonded to the carbon atom at position 3 of the pyrrole ring. After vacuum drying, the product is dissolved in acetic acid (AcOH), and silver acetate (AcOAg) is added (step C1b). The iodine bonded to the carbon atom at position 3 of the pyrrole ring is then replaced with an acetoxy group (-OAc). Sufficient dehydration by the vacuum drying improves the yield. In this way, the polyindigo monomer according to this embodiment is produced. Bromine may be used instead of iodine in step C1a. Other reactants, catalysts, and solvents that produce the above-mentioned products may also be used in steps A to C1b.

[0082] (Example 4 of Manufacturing Method 1) The following chemical reaction formula (15) shows a method for producing a polyindigo monomer by Production Method 1 using 2,4-dinitro-m-xylene (or a derivative thereof) as a starting material.

[0083] [ka]

[0084] As shown in this scheme, the Reingruber-Bachcho reaction of 2,4-dinitro-m-xylene (or its derivatives) produces benzo[1,2-b:5,4-b]dipyrrole (and derivatives). Specifically, dimethylformamide dimethyl acetal is added in DMF (dimethylformamide) solvent to increase the carbon number (Step A). ​​Next, this substance is ring-closed by the action of hydrazine using iron chloride hexahydrate (FeCl3·6H2O) as a catalyst (Step B), producing the pyrrole ring.

[0085] Next, the benzo[1,2-b:5,4-b]dipyrrole (and derivatives) produced in step B is dissolved in a water / methanol mixture (MeOH / HO), and potassium iodide (KI), iodine (I), and sodium hydroxide (NaOH) are added for iodination (step C1a). The iodine atom (I) is bonded to the carbon atom at position 3 of the pyrrole ring. After vacuum drying, the product is dissolved in acetic acid (AcOH), and silver acetate (AcOAg) is added (step C1b). The iodine bonded to the carbon atom at position 3 of the pyrrole ring is then replaced with an acetoxy group (-OAc). Sufficient dehydration by the vacuum drying improves the yield. Thus, the polyindigo monomer of this embodiment is produced. Bromine may be used instead of iodine in step C1a. Other reactants, catalysts, and solvents that produce the above-mentioned products may also be used in steps A to C1b.

[0086] (Example 1 of Manufacturing Method 2) The following chemical reaction formula (16) shows a method for producing a polyindigo monomer by Production Method 2 using 2,5-dinitro-p-xylene (or a derivative thereof) as a starting material.

[0087] [ka]

[0088] As shown in this formula, 2,5-dinitro-p-xylene (or its derivatives) undergoes the Reingruber-Bachau reaction to produce benzo[1,2-b:4,5-b]dipyrrole (and derivatives). Steps A and B are the same as those in Example 3 of Production Method 1 (see Chemical Reaction Formula (14)), so their explanation is omitted here.

[0089] Next, benzo[1,2-b:4,5-b]dipyrrole (and derivatives) produced in Step B are added to bromomethylbenzene in DMF (dimethylformamide) with sodium hydride (NaH) to add a benzyl group (-Bn) (Step C2a). The benzyl group then bonds to the nitrogen atom (N) of the pyrrole ring. This product is then dissolved in a mixture of acetonitrile (MeCN) and potassium hydroxide (KOH), and treated with (diacetoxyiodo)benzene (DAIB) using palladium acetate (Pd(OAc)2) as a catalyst (Step C2b). This results in an acetoxy group (-OAc) being attached to the carbon atom at the 3-position of the pyrrole ring.

[0090] Subsequently, hydrogen (H2) is reacted with palladium carbon (Pd / C) as a catalyst (step C2c) to eliminate the benzyl group. In this way, the polyindigo monomer according to this embodiment is produced. In steps A to C2c, other reactants, catalysts, and solvents that produce the above-mentioned products may be used.

[0091] (Example 2 of Manufacturing Method 2) The following chemical reaction formula (17) shows a method for producing a polyindigo monomer by Production Method 2 using 2,4-dinitro-m-xylene (or a derivative thereof) as a starting material.

[0092] [ka]

[0093] As shown in this formula, 2,4-dinitro-m-xylene (or its derivatives) undergoes the Reingruber-Bachcho reaction to produce benzo[1,2-b:5,4-b]dipyrrole (and derivatives). Steps A and B are the same as those in Example 4 of Production Method 1 (see Chemical Reaction Formula (15)), so their explanation is omitted here.

[0094] Next, benzo[1,2-b:5,4-b]dipyrrole (and derivatives) produced in Step B are added to bromomethylbenzene in DMF (dimethylformamide) with sodium hydride (NaH) to add a benzyl group (-Bn) (Step C2a). The benzyl group then bonds to the nitrogen atom (N) of the pyrrole ring. This product is then dissolved in a mixture of acetonitrile (MeCN) and potassium hydroxide (KOH), and treated with (diacetoxyiodo)benzene (DAIB) using palladium acetate (Pd(OAc)2) as a catalyst (Step C2b). This results in an acetoxy group (-OAc) being attached to the carbon atom at the 3-position of the pyrrole ring.

[0095] Subsequently, hydrogen (H2) is reacted with palladium carbon as a catalyst (step C2c) to eliminate the benzyl group. In this way, the polyindigo monomer according to this embodiment is produced. In steps A to C2c, other reactants, catalysts, and solvents that produce the above-mentioned products may be used.

[0096] (Example 3 of Manufacturing Method 2) The following chemical reaction formula (18) shows a method for producing a polyindigo monomer by Production Method 2 using 3,3'-dimethyl-4,4'-dinitrobiphenyl (or its derivative) as a starting material. As shown in this formula, 3,3'-dimethyl-4,4'-dinitrobiphenyl (or its derivative) undergoes the Reingruber-Bachcho reaction. Steps A and B are the same as those in Example 1 of Production Method 1 (see chemical reaction formula (12)), so a detailed explanation is omitted.

[0097] [ka]

[0098] Next, the product of Step B is treated with bromomethylbenzene in DMF (dimethylformamide) solvent together with sodium hydride (NaH) to add a benzyl group (-Bn) (Step C2a). The benzyl group then bonds to the nitrogen atom of the pyrrole ring. This product is then dissolved in a mixture of acetonitrile (MeCN) and potassium hydroxide (KOH), and treated with (diacetoxyiodo)benzene (DAIB) using palladium acetate (Pd(OAc)2) as a catalyst (Step C2b). This results in an acetoxy group (-OAc) being attached to the carbon atom at the 3-position of the pyrrole ring.

[0099] Subsequently, hydrogen (H2) is reacted with palladium carbon (Pd / C) as a catalyst (step C2c) to eliminate the benzyl group. In this way, the polyindigo monomer according to this embodiment is produced. In steps A to C2c, other reactants, catalysts, and solvents that produce the above-mentioned products may be used.

[0100] In the production method according to this embodiment, polyindigo monomer (chemical formula (1)) can be produced as described above. In addition to the processes described above, the production method according to this embodiment can also use various processes in which a substance having two pyrrole rings (chemical formula (5)) is produced by the Reingruber-Batcho reaction and the carbon atom at the 3-position of the pyrrole ring is acetoxylated.

[0101] (Example 4 of Manufacturing Method 2) The following chemical reaction formula (19) shows a method for producing polyindigo monomers by Production Method 2 using 4,4'-dimethyl-3,3'-dinitrobiphenyl (or its derivatives) as a starting material. As shown in this formula, 4,4'-dimethyl-3,3'-dinitrobiphenyl (or its derivatives) undergoes the Reingruber-Bachcho reaction. Steps A and B are the same as those in Example 2 of Production Method 1 (see Chemical Reaction Formula (13)), and therefore their explanation is omitted here.

[0102] [ka]

[0103] Next, the product of Step B is treated with bromomethylbenzene in DMF (dimethylformamide) solvent together with sodium hydride (NaH) to add a benzyl group (-Bn) (Step C2a). The benzyl group then bonds to the nitrogen atom of the pyrrole ring. This product is then dissolved in a mixture of acetonitrile (MeCN) and potassium hydroxide (KOH), and treated with (diacetoxyiodo)benzene (DAIB) using palladium acetate (Pd(OAc)2) as a catalyst (Step C2b). This results in an acetoxy group (-OAc) being attached to the carbon atom at the 3-position of the pyrrole ring.

[0104] Subsequently, hydrogen (H2) is reacted with palladium carbon (Pd / C) as a catalyst (step C2c) to eliminate the benzyl group. In this way, the polyindigo monomer according to this embodiment is produced. In steps A to C2c, other reactants, catalysts, and solvents that produce the above-mentioned products may be used.

[0105] In the production method according to this embodiment, polyindigo monomer (chemical formula (1)) can be produced as described above. In addition to the processes described above, the production method according to this embodiment can also use various processes in which a substance having two pyrrole rings (see chemical reaction formulas (6) and (7)) is produced by the Reingruber-Batcho reaction, and the carbon atom at the 3-position of the pyrrole ring is acetoxylated.

[0106] [Method of producing 3,3'-dimethyl-4,4'-dinitrobiphenyl] The above-mentioned 3,3'-dimethyl-4,4'-dinitrobiphenyl (the starting material for Example 1 of Production Method 1 and Example 3 of Production Method 2) can be prepared using Suzuki-Miyaura cross-coupling. The following chemical reaction formula (20) shows the preparation method of 3,3'-dimethyl-4,4'-dinitrobiphenyl.

[0107] [ka]

[0108] [Method of producing 4,4'-dimethyl-3,3'-dinitrobiphenyl] The above-mentioned 4,4'-dimethyl-3,3'-dinitrobiphenyl (the starting material for Example 2 of Production Method 1 and Example 4 of Production Method 2) can be prepared using Suzuki-Miyaura cross-coupling. The following chemical reaction formula (21) shows the preparation method of 4,4'-dimethyl-3,3'-dinitrobiphenyl.

[0109] [ka]

[0110] [Polyindigo manufacturing method] A method for producing polyindigo according to this embodiment will be described. The polyindigo according to this embodiment can be produced by polymerizing the polyindigo monomer according to this embodiment described above. The following chemical reaction formula (22) shows the method for producing polyindigo according to this embodiment.

[0111] [ka]

[0112] In the formula, M + is a cation in a base, e.g., sodium ion (Na + ). As shown in chemical reaction formula (22), when the polyindigo monomer is subjected to weakly basic conditions, the acetyl group (-Ac) in the acetoxy group (-OAc) is eliminated by hydrolysis. As described above, in the polyindigo monomer according to this embodiment, an acetoxy group (-OAc) is bonded to the carbon atom at the 3-position of each pyrrole ring, but an acetyl group (-Ac) is not bonded to the nitrogen atom (N) of each pyrrole ring. Therefore, by using weakly basic conditions, the acetyl group in the acetoxy group can be easily eliminated.

[0113] If an acetyl group is bonded to the nitrogen atom of the pyrrole ring, the bond is an amide bond, which cannot be easily removed, and treatment with a strong base or strong acid is required. In this case, a ring-opening reaction or sulfonation of the pyrrole ring may occur, which may result in a decrease in yield or the inclusion of by-products. In contrast, in the polyindigo monomer according to this embodiment, an acetyl group is not bonded to the nitrogen atom of the pyrrole ring, and therefore such treatment with a strong base or strong acid is not required.

[0114] After the acetyl group in the acetoxy group is eliminated, the substance is oxidized in air to cause a polymerization reaction, producing polyindigo.

[0115] The following chemical reaction formulas (23) to (26) show specific polymerization reactions of polyindigo monomers according to this embodiment.

[0116] [ka]

[0117] [ka]

[0118] [ka]

[0119] [ka]

[0120] The polyindigo according to this embodiment may be produced by polymerizing multiple types of polyindigo monomers according to this embodiment. Alternatively, the polyindigo according to this embodiment may be produced by polymerizing one or more types of polyindigo monomers according to this embodiment with a polyindigo monomer that does not have the structure according to this embodiment.

[0121] Although the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and various modifications can be made, as a matter of course. [Example]

[0122] Example 1. Production of benzo[1,2-b:4,5-b]dipyrrole 26.25 g of 2,5-dinitro-p-xylene was dissolved in 110 ml of dimethylformamide, and 3 molar equivalents of dimethylformamide dimethyl acetal was added. The mixture was heated to 105°C under a nitrogen atmosphere and stirred for 20 hours. Then, it was cooled to room temperature, and the precipitate was collected by filtration and washed with methanol and water.

[0123] The precipitate was dried under reduced pressure and then dissolved in 180 ml of methanol. Iron chloride hexahydrate was used as a catalyst, and 40 ml of hydrazine monohydrate was added. The mixture was stirred at 45°C for 30 minutes. The precipitate was then added to the reaction system in several portions (7.94 g in total) and stirred at 45°C for 12 hours. The mixture was filtered through Celite, and the filtrate was evaporated under reduced pressure. It was then extracted with dichloromethane and washed with saturated aqueous sodium chloride and water. The resulting organic layer was then evaporated under reduced pressure to obtain benzo[1,2-b:5,4-b]dipyrrole.

[0124] Example 2. Preparation of 3,7-diacetoxybenzo[1,2-b:4,5-b]dipyrrole Benzo[1,2-b:4,5-b]dipyrrole (0.352 g) was dissolved in a water / methanol mixture (5 mL water, 25 mL methanol) and iodized with sodium hydroxide (0.259 g), potassium iodide (0.932 g), and iodine (1.407 g) added in portions. The reaction time was 3 hours. The product was dissolved in acetic acid (20 mL), silver acetate (2.0 g) was added, and the mixture was stirred at 90°C for 2 hours to yield 3,7-diacetoxybenzo[1,2-b:4,5-b]dipyrrole (0.69 g).

[0125] Example 3. Production of polyindigo 3,7-Diacetoxybenzo[1,2-b:4,5-b]dipyrrole was added to 20 mL of 1 mol / L aqueous sodium hydroxide solution and stirred for 1 hour. Polyindigo was produced by blowing air into the solution under basic conditions.

Claims

1. A polyindigo monomer represented by the following chemical formula (1). 【Chemistry 1】 [wherein Ar represents an aryl group, and Ac represents an acetyl group]

2. The polyindigo monomer according to claim 1, the aryl group is any one of a phenyl group, a biphenyl group, a naphthyl group, a phenyl group modified with a substituent, a biphenyl group modified with a substituent, and a naphthyl group modified with a substituent; The substituent is at least one of a halogeno group and an alkyl group. Polyindigo monomer.

3. The polyindigo monomer according to claim 2, A polyindigo monomer represented by the following chemical formula (2). 【Chemistry 2】 [In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

4. The polyindigo monomer according to claim 2, A polyindigo monomer represented by the following chemical formula (3). 【Transformation 3】 [In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

5. The polyindigo monomer according to claim 2, A polyindigo monomer represented by the following chemical formula (4). 【Chemistry 4】 [In the formula, R １ and R ２ represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

6. The polyindigo monomer according to claim 2, A polyindigo monomer represented by the following chemical formula (5). 【Transformation 5】 [In the formula, R １ and R ２ represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

7. By the Leimgruber-Batcho reaction, a substance represented by the following chemical formula (6) is produced: An acetoxy group is added to the carbon atom at the 3rd position of the pyrrole ring of the substance. Method for producing polyindigo monomer. 【Transformation 6】 [wherein Ar represents an aryl group]

8. A method for producing the polyindigo monomer according to claim 7, comprising: In the step of adding the acetoxy group, a halogeno group is bonded to the carbon atom at the 3-position of the pyrrole ring of the substance, and then silver acetate is supplied to replace the halogeno group with an acetoxy group. Method for producing polyindigo monomer.

9. A method for producing the polyindigo monomer according to claim 7, comprising: In the step of adding the acetoxy group, a benzyl group is bonded to the nitrogen atom of the pyrrole ring of the substance, and then (diacetoxyiodo)benzene is supplied to bond an acetoxy group to the carbon atom at the 3-position of the pyrrole ring, and then the benzyl group is removed. Method for producing polyindigo monomer

10. A method for producing the polyindigo monomer according to claim 8, comprising the steps of: In the step of producing a substance represented by the above chemical formula (6), Using 3,3'-dimethyl-4,4'-dinitrobiphenyl or its derivative as a starting material, a substance represented by the following chemical formula (7) is produced by the Reingruber-Bachau reaction. Method for producing polyindigo monomer. 【Transformation 7】 [In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

11. A method for producing the polyindigo monomer according to claim 8, comprising the steps of: In the step of producing a substance represented by the above chemical formula (6), Using 4,4'-dimethyl-3,3'-dinitrobiphenyl or its derivative as a starting material, a substance represented by the following chemical formula (8) is produced by the Reingruber-Bachau reaction. Method for producing polyindigo monomer. 【Transformation 8】 [In the formula, R １ , R ２ , R ３ , R ４ , R ５ and R ６ represents hydrogen, a halogeno group, an alkyl group, a phenyl group, or a benzyl group.

12. A method for producing the polyindigo monomer according to claim 9, comprising: In the step of producing a substance represented by the above chemical formula (6), Using 2,5-dinitro-p-xylene or its derivative as a starting material, a substance represented by the following chemical formula (9) is produced by the Reingruber-Bachau reaction. Method for producing polyindigo monomer. 【Chemistry 9】 [In the formula, R １ and R ２ represents hydrogen, a halogen group, or an alkyl group.

13. A method for producing the polyindigo monomer according to claim 9, comprising: In the step of producing a substance represented by the above chemical formula (6), Using 2,4-dinitro-m-xylene or its derivative as a starting material, a substance represented by the following chemical formula (10) is produced by the Reingruber-Bachau reaction. Method for producing polyindigo monomer. 【Chemistry 10】 [In the formula, R １ and R ２ represents hydrogen, a halogen group, or an alkyl group.

14. By eliminating the acetyl group from a polyindigo monomer represented by the following chemical formula (1), The polyindigo monomer from which the acetyl group has been removed is polymerized to produce polyindigo. How to make polyindigo. 【Chemistry 11】 [wherein Ar represents an aryl group, and Ac represents an acetyl group]

Images