KR20200014004A - Organocatalyst and method for alcoholysis of polycarbonate using the same - Google Patents

Abstract

The present invention relates to a method of decomposing polycarbonate, which comprises the step of alcoholyzing any one organocatalyst selected from guanidine derivatives and amidine derivatives and poly(bisphenol A carbonate) into bisphenol A and carbonate under an alcohol condition. Therefore, the method according to the present invention enables poly(bisphenol A carbonate) to be decomposed into bisphenol A and dimethyl carbonate, i.e., raw materials under a mild condition and a low catalytic loading. Further, the method according to the present invention can simplify a reaction process and enables a decomposition process to be designed so that the decomposition process does not need an auxiliary solvent.

Description

ORGANOCATALYST AND METHOD FOR ALCOHOLYSIS OF POLYCARBONATE USING THE SAME}

The present invention relates to an organic catalyst and a method for decomposing an alcohol of polycarbonate using the same, and more particularly, to a method for decomposing and recovering a polycarbonate into bisphenol A and an organic carbonate by using a guanidine derivative catalyst for alcohol decomposition of the polycarbonate. will be.

Polycarbonate (PC) is a thermoplastic polymer prepared by condensation of bisphenol A with carbonyl raw material phosgene or diphenyl carbonate. It is a state-of-the-art engineering plastic with a variety of excellent properties such as high resistance and ductility, good visual transparency, flame retardancy and relatively low manufacturing cost. Their uses are wide ranging and range from daily use items to special applications such as digital storage media, electronic housings, architectural and building glass materials, containers, automotive parts, medical applications and protective supplies. Therefore, the annual production capacity of PCs is gradually increasing to 6 million tons per year.

However, the PC industry is concerned about the environment and health. Bisphenol A, a major component of PC, is regarded as xenoestrogen, which acts like an estrogen in the human body. Because of concerns about the potential hormonal disturbance effects of bisphenol A, there has been concern with the use of polycarbonates, particularly as articles in contact with humans such as food containers and water bottles. Although polycarbonate is a potential reservoir of bisphenol A, much attention is not paid to the reuse of polycarbonies. PCs are currently treated as other items in plastic recycling systems, and many PC wastes are mixed with other plastics and landfilled. In addition, despite low reaction rates, the progressive degradation of polycarbonates releases significant amounts of bisphenol A into the ecosystem in an unrenewable form. In applications using high purity polycarbonates, such as compact discs and water bottles, only a small fraction of the waste is used for mechanical recycling. However, deterioration in mechanical processing means that recycled products can only be used for low end applications. After several recycling, the PC eventually goes to a municipal waste disposal or combustion facility.

What is needed to reuse the polycarbonate is chemical decomposition into monomers. Converting end-of-life plastics into valuable chemicals is another sustainable recycling method. The decomposition of polycarbonates is known for pyrolysis, hydrolysis and alcohol degradation.

Pyrolysis not only requires harsh conditions but also produces a mixture of compounds due to pyrolysis. Therefore, a more selective decomposition technique is required, and hydrolysis of the PC has also been investigated. Many excellent catalyst systems and conditions have been reported. However, the carbonyl portion of the polymer was converted to unstable carbonic acid and only bisphenol A was regenerated. Methanolysis, on the other hand, allowed the recovery of carbonyl with bisphenol A and dimethyl carbonate (DMC). In addition, bisphenol A and dimethyl carbonate (DMC) are the raw materials for producing polycarbonate. An industrial melting process developed by Asahi Kasei uses dimethyl carbonate to produce diphenyl carbonate, which is polymerized with BPA instead of dangerous phosgene.

Efficient methanolysis of polycarbonates enabled a complete chemistry-life cycle. Despite these advantages, only the ionic liquid and alkali metal mediated polycarbonate methanoly decomposition of polycarbonate is limited and in general, most systems require high temperature and high pressure or heavy metal catalysts for efficient bisphenol A recovery. Doing.

Korean Laid-Open Patent Publication No. 2015-0029750 Japanese Laid-Open Patent Publication No. 2009-027882

An object of the present invention is to solve the above problems by using an organic catalyst of a guanidine derivative such as TBD as a catalyst for alcohol decomposition of polycarbonate, the polycarbonate is completely organic with bisphenol A under mild conditions and low catalyst loading conditions. The present invention provides a method for decomposing and recovering carbonate, thereby preventing ecosystem leakage of bisphenol A, known as an endocrine disruptor, and reusing the recovered organic catalyst.

Another object of the present invention is the same substance as organic carbonate produced after alcohol decomposition without co-solvent in organic solvent used in alcohol decomposition of polycarbonate using organic catalyst of guanidine derivative such as TBD, for example dimethyl carbonate By using to reduce the type of the final product after the alcohol decomposition to three kinds of bisphenol A, alcohol and organic carbonate to provide a method for decomposition of polycarbonate that can simplify the purification process after the reaction.

Another object of the present invention is to provide a method for decomposing a polycarbonate, which can selectively prepare the required organic carbonate according to the type of alcohol used for alcohol decomposition of the polycarbonate.

According to one aspect of the invention,

Provided are guanidine derivatives for catalysts used in alcohol decomposition reactions that decompose polycarbonates into bisphenol A and organic carbonates.

Preferably, the guanidine derivative for the catalyst may be represented by the following structural formula (1).

[Formula 1]

In structure 1,

R ¹ and R ² are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group, or R ¹ and R ² are bonded to each other and substituted or unsubstituted fused together with three atoms therebetween To form a C1 to C30 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C30 heteroaryl group,

R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,

또는

이고,X is

or

ego,

R ⁵ to R ⁷ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group.

More preferably, in Structural Formula 1,

R ¹ and R ² combine with each other to form a substituted or unsubstituted fused C1 to C5 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C5 heteroaryl group with three atoms therebetween,

R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,

이고,X is

ego,

R ⁵ may be a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

Most preferably, the guanidine derivative may be TBD (1,5,7-triazabicyclo [4.4.0] -dec-5-ene).

According to another aspect of the invention,

Guanidine derivatives There is provided a process for decomposing polycarbonate, which comprises alcoholic decomposition of poly (bisphenol A carbonate) to bisphenol A and carbonate under organic catalyst and alcohol conditions. .

Preferably, the guanidine derivative may be represented by the following Structural Formula 1.

[Formula 1]

In structure 1,

R ¹ and R ² are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group, or R ¹ and R ² are bonded to each other and substituted or unsubstituted fused together with three atoms therebetween To form a C3 to C30 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C30 heteroaryl group,

R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,

또는

이고,X is

or

ego,

R ⁵ to R ⁷ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group.

More preferably, in Structural Formula 1,

R ¹ and R ² combine with each other to form a substituted or unsubstituted fused C1 to C5 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C5 heteroaryl group with three atoms therebetween,

R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,

이고,X is

ego,

R ⁵ may be a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

Most preferably, the guanidine derivative may be TBD (1,5,7-triazabicyclo [4.4.0] -dec-5-ene).

The organic catalyst may be loaded in an amount of 0.01 to 5 mol% based on the polycarbonate.

이고, R⁸ 및 R⁹는 서로 같거나 다르고, 각각 독립적으로 수소원자, C1 내지 C30 알킬기, 또는 C3 내지 C30 시클로알킬기, C6 내지 C30 아릴기이거나, 또는 R⁸ 및 R⁹는 서로 결합하여 그들 사이의 2개의 탄소원자와 함께 융합된 C3 내지 C30 시클로알킬기, 또는 치환 또는 비치환된 융합된 C6 내지 C30 아릴기를 형성하는 것일 수 있다.The alcohol used to decompose the alcohol is methanol, ethanol or

R ⁸ and R ⁹ are the same as or different from each other, and each independently a hydrogen atom, a C1 to C30 alkyl group, or a C3 to C30 cycloalkyl group, a C6 to C30 aryl group, or R ⁸ and R ⁹ are bonded to each other It may be to form a fused C3 to C30 cycloalkyl group, or a substituted or unsubstituted fused C6 to C30 aryl group with two carbon atoms of.

The solvent used in the alcohol decomposition may be the same organic carbonate as the organic carbonate produced according to the type of alcohol after alcohol decomposition.

Preferably, the alcohol used in the alcohol decomposition may be methanol. In this case, the solvent used for alcohol decomposition may be dimethyl carbonate.

The alcohol decomposition may be carried out at 20 to 300 ℃.

The alcohol decomposition may be performed for 1 to 100 hours.

After the alcohol decomposition, the step of recovering the bisphenol A by purifying the solid mixture produced by evaporating the volatiles may be further performed.

After the alcohol decomposition, the solid mixture produced by evaporating the volatiles may be dissolved in an organic solvent to filter the suspension to recover the solid containing the organic catalyst.

The organic solvent is diethyl ether, dichloroethyl ether, diisopropyl ether, n-butyl ether, diisoamyl ether, methylphenyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl acetate, ethyl Any one selected from acetate, methyl cellosorb acetate, ethyl cellosorb acetate, diethyl cellosorb acetate, methylethyl carbitol, diethyl carbitol, diethylene glycol monomethyl ether, and diethylene glycol monoethyl ether Can be.

Bisphenol A may be recovered by centrifuging the solution dissolved in the organic solvent.

The solid comprising the organic catalyst may be reused once to multiple times in the next cycle of decomposing the polycarbonate.

The reuse may be repeated five or more times in a continuous cycle.

The polycarbonate decomposition method of the present invention uses organic catalysts of guanidine derivatives, such as TBD, as catalysts for alcohol decomposition of polycarbonates, thereby completely separating polycarbonates with bisphenol A under mild conditions and low catalyst loading conditions. It can be decomposed into carbonate and recovered, thereby preventing the leakage of the ecosystem of bisphenol A, known as endocrine disruptor, and reusing the recovered organic catalyst.

In addition, the decomposition method of the polycarbonate of the present invention is an organic solvent used in the alcohol decomposition of polycarbonate using an organic catalyst of a guanidine derivative such as TBD, the same substance as the organic carbonate produced after alcohol decomposition without using a cosolvent, For example, by using dimethyl carbonate, the final product after alcohol decomposition can be reduced to three kinds of bisphenol A, alcohol and organic carbonate to simplify the post-reaction purification process.

In addition, the polycarbonate decomposition method of the present invention can selectively produce the organic carbonate required according to the type of alcohol used for alcohol decomposition of the polycarbonate.

Figure 1 shows a schematic diagram of the alcohol decomposition of the polycarbonate of the present invention.
2 shows a series of catalysts known to exhibit high reactivity in transesterification.
3 is a photograph of the results of chemical degradation of PC after use in accordance with Example 3. FIG.
4 is a result of 1H-NMR analysis of polycarbonate decomposition.
5 is a result of 1 H-NMR analysis of the organic catalytic reaction with diphenyl carbonate (DPC).
6 shows the results of polymer material molecular weight (GPC) analysis according to Test Example 4.
7 illustrates one reaction mechanism of polycarbonate degradation.

Hereinafter, various aspects and various embodiments of the present invention will be described in more detail.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention.

However, the following descriptions are not intended to limit the present invention to specific embodiments, and detailed descriptions of well-known technologies related to the present invention will be omitted when it is determined that the present invention may obscure the gist of the present invention. .

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, or combination thereof described in the specification, and one or more other features or It is to be understood that the present invention does not exclude the possibility of adding or presenting numbers, steps, operations, components, or combinations thereof.

As used herein, unless otherwise defined, the term "atom bond" means a single bond, a double bond, or a triple bond.

"Substituted" means that at least one hydrogen atom is deuterium, C1 to C30 alkyl group, C3 to C30 cycloalkyl group, C2 to C30 heterocycloalkyl group, C1 to C30 halogenated alkyl group, C6 to C30 aryl group, C1 to C30 heteroaryl group, C1 to C30 alkoxy group, C2 to C30 alkenyl group, C2 to C30 alkynyl group, C6 to C30 aryloxy group, silyloxy group (-OSiH ₃ ), -OSiR ¹ H ₂ (R ¹ is C1 to C30 alkyl group or C6 to C30 aryl group), -OSiR ¹ R ² H (R ¹ and R ² are each independently a C1 to C30 alkyl group or C6 to C30 aryl group), -OSiR ¹ R ² R ³ , (R ¹ , R ² , and R ³ is each independently C1 to C30 alkyl group or C6 to C30 aryl group), C1 to C30 acyl group, C2 to C30 acyloxy group, C2 to C30 heteroaryloxy group, C1 to C30 sulfonyl group, C1 to C30 alkylthiol group , C6 to C30 arylthiol group, C1 to C30 heterocyclothiol group, C1 to C30 phosphate amide group, silyl group (S iR ¹ R ² R ³ ₎ (R ¹ , R ² , and R ³ are each independently a hydrogen atom, a C1 to C30 alkyl group or a C6 to C30 aryl group), an amine group (-NRR ') (where R and R Are each independently a substituent selected from the group consisting of a hydrogen atom, a C1 to C30 alkyl group, and a C6 to C30 aryl group), a carboxyl group, a halogen group, a cyano group, a nitro group, an azo group, and a hydroxy group It means what is substituted by the substituent.

In addition, two adjacent substituents of the substituents may be fused to form a saturated or unsaturated ring.

In addition, the carbon number range of the alkyl group or the aryl group in the "substituted or unsubstituted C1 to C30 alkyl group" or "substituted or unsubstituted C6 to C30 aryl group", and the like, is unsubstituted without considering the portion substituted with the substituent. It means the total carbon number constituting the alkyl moiety or aryl moiety as viewed. For example, a phenyl group substituted with a butyl group in the para position means a aryl group having 6 carbon atoms substituted with a butyl group having 4 carbon atoms.

In addition, in the "substituted or unsubstituted C6 to C30 fused aryl group" and the like, the carbon number range of the fused aryl group is fused when it is considered to be unsubstituted without considering the substituted part, and is newly formed. It means the total carbon number which comprises an aryl part.

As used herein, unless otherwise defined, "hetero" means containing 1 to 4 heteroatoms selected from the group consisting of N, O, S, and P in one functional group, and the remainder is carbon.

In the present specification, "hydrogen" means monotium, dihydrogen, or tritium unless otherwise defined.

As used herein, unless otherwise defined, an "alkyl group" means an aliphatic hydrocarbon group.

The alkyl group may be a "saturated alkyl group" that does not contain any double or triple bonds.

The alkyl group may be an "unsaturated alkyl group" containing at least one double or triple bond.

The alkyl group may be a C1 to C30 alkyl group. More specifically, it may be a C1 to C20 alkyl group, a C1 to C10 alkyl group, or a C1 to C6 alkyl group.

For example, a C1 to C4 alkyl group has 1 to 4 carbon atoms in the alkyl chain, i.e., the alkyl chain is methyl, ethyl, propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl and t-butyl Selected from the group consisting of:

Specific examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, t-butyl, pentyl, hexyl, ethenyl, propenyl, butenyl, cyclopropyl and cyclo A butyl group, a cyclopentyl group, a cyclohexyl group, etc. are meant.

"Amine group" includes an amino group, an arylamine group, an alkylamine group, an arylalkylamine group, or an alkylarylamine group, and may be represented by -NRR ', wherein R and R' are each independently a hydrogen atom , A C1 to C30 alkyl group, and a C6 to C30 aryl group.

"Cycloalkyl groups" include monocyclic or fused polycyclic (ie, rings that divide adjacent pairs of carbon atoms) functional groups.

"Heterocycloalkyl group" means containing 1 to 4 heteroatoms selected from the group consisting of N, O, S and P in the cycloalkyl group, and the rest are carbon. When the heterocycloalkyl group is a fused ring, at least one ring of the fused rings may include 1 to 4 heteroatoms.

"Aromatic group" means a functional group in which all elements of the functional group in the ring form have p-orbitals, and these p-orbitals form conjugation. Specific examples include an aryl group and a heteroaryl group.

An "aryl group" includes a monocyclic or fused ring polycyclic (ie, a ring that divides adjacent pairs of carbon atoms) functional groups.

"Heteroaryl group" means containing 1 to 4 heteroatoms selected from the group consisting of N, O, S and P in the aryl group, the rest being carbon. When the heteroaryl group is a fused ring, at least one ring of the fused ring may include 1 to 4 heteroatoms.

The number of atoms of the ring in the aryl group and heteroaryl group is the sum of the number of carbon atoms and non-carbon atoms.

Figure 1 shows a schematic diagram of the alcohol decomposition of the polycarbonate of the present invention. Hereinafter, with reference to Figure 1 will be described for the alcohol decomposition method of the polycarbonate of the present invention and the catalyst used in the method.

Guanidine derivatives for catalysts of the present invention are characterized in that they are used in alcohol decomposition reactions that decompose polycarbonates into bisphenol A and organic carbonates.

Preferably, the guanidine derivative for the catalyst may be represented by the following structural formula (1).

[Formula 1]

In structure 1,

R ¹ and R ² are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group, or R ¹ and R ² are bonded to each other and substituted or unsubstituted fused together with three atoms therebetween To form a C1 to C30 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C30 heteroaryl group,

R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,

또는

이고,X is

or

ego,

R ⁵ to R ⁷ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group.

More preferably, in Structural Formula 1,

R ¹ and R ² combine with each other to form a substituted or unsubstituted fused C1 to C5 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C5 heteroaryl group with three atoms therebetween,

R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,

이고,X is

ego,

R ⁵ may be a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group.

Most preferably, the guanidine derivative may be TBD (1,5,7-triazabicyclo [4.4.0] -dec-5-ene).

이고, R⁸ 및 R⁹는 서로 같거나 다르고, 각각 독립적으로 수소원자, C1 내지 C30 알킬기, 또는 C3 내지 C30 시클로알킬기, C6 내지 C30 아릴기이거나, 또는 R⁸ 및 R⁹는 서로 결합하여 그들 사이의 2개의 탄소원자와 함께 융합된 C3 내지 C30 시클로알킬기, 또는 치환 또는 비치환된 융합된 C6 내지 C30 아릴기를 형성하는 것일 수 있다.
The alcohol is methanol, ethanol or

R ⁸ and R ⁹ are the same as or different from each other, and each independently a hydrogen atom, a C1 to C30 alkyl group, or a C3 to C30 cycloalkyl group, a C6 to C30 aryl group, or R ⁸ and R ⁹ are bonded to each other It may be to form a fused C3 to C30 cycloalkyl group, or a substituted or unsubstituted fused C6 to C30 aryl group with two carbon atoms of.

Hereinafter, the decomposition method of the polycarbonate of the present invention will be described.

Decomposition method of the polycarbonate of the present invention comprises the step of alcohol decomposition of polycarbonate (Poly (bisphenol A carbonate)) with bisphenol A and carbonate under guanidine derivatives organic catalyst and alcohol conditions It is characterized by.

The guanidine derivative is preferably a compound represented by the formula (1) as described above.

Most preferably, the guanidine derivative may be TBD (1,5,7-triazabicyclo [4.4.0] -dec-5-ene).

The organic catalyst is preferably loaded in an amount of 0.01 to 5 mol%, more preferably 1.0 to 4 mol%, based on the polycarbonate. The present invention can provide an efficient system capable of completely degrading polycarbonate even with a small amount of loading of the organic catalyst.

이고, R⁸ 및 R⁹는 서로 같거나 다르고, 각각 독립적으로 수소원자, C1 내지 C30 알킬기, 또는 C3 내지 C30 시클로알킬기, C6 내지 C30 아릴기이거나, 또는 R⁸ 및 R⁹는 서로 결합하여 그들 사이의 2개의 탄소원자와 함께 융합된 C3 내지 C30 시클로알킬기, 또는 치환 또는 비치환된 융합된 C6 내지 C30 아릴기를 형성할 수 있다.The alcohol is methanol, ethanol or

R ⁸ and R ⁹ are the same as or different from each other, and each independently a hydrogen atom, a C1 to C30 alkyl group, or a C3 to C30 cycloalkyl group, a C6 to C30 aryl group, or R ⁸ and R ⁹ are bonded to each other Together with two carbon atoms of C 3 to C 30 cycloalkyl group, or a substituted or unsubstituted fused C 6 to C 30 aryl group.

The solvent used in the alcohol decomposition is preferably used the same organic carbonate as the organic carbonate produced according to the type of alcohol after alcohol decomposition.

For example, it is preferable to use dimethyl carbonate, which is an organic carbonate produced when methanol is added, as the solvent used for the alcohol used in the alcohol decomposition is methanol. Accordingly, the species of the final product after alcohol decomposition can be reduced to three kinds of bisphenol A, methanol and dimethyl carbonate, thereby simplifying the purification process.

The alcohol decomposition is preferably carried out at 20 to 300 ℃, more preferably may be carried out in mild conditions of 30 to 150 ℃, even more preferably 50 to 75 ℃.

Under the above temperature conditions, the alcohol decomposition is preferably performed for 1 to 100 hours, more preferably for 1.5 hours to 50 hours, even more preferably for 2 hours to 6 hours. .

After the alcohol decomposition, the step of recovering the bisphenol A by purifying the solid mixture produced by evaporating the volatiles may be further performed.

Meanwhile, after the alcohol decomposition, the solid mixture generated by evaporating the volatile substance may be dissolved in an organic solvent to filter the suspension to recover the solid including the organic catalyst.

The solid comprising the organic catalyst can be used again in subsequent cycles to decompose the polycarbonate, thereby reducing the catalyst usage.

The reuse may be repeated in the same way in successive cycles.

The organic solvent is diethyl ether, dichloroethyl ether, diisopropyl ether, n-butyl ether, diisoamyl ether, methylphenyl ether, tetrahydrofuran, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, methyl acetate, ethyl Acetate, methyl cellosorb acetate, ethyl cellosorb acetate, diethyl cellosorb acetate, methylethyl carbitol, diethyl carbitol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and the like can be used. The scope of the present invention is not limited to this.

Bisphenol A may be recovered by centrifuging the solution dissolved in the organic solvent.

Hereinafter, an embodiment according to the present invention will be described in detail.

[ Example ]

Example  1: polycarbonate decomposition ( depolymerization )

Polycarbonate (PC) (0.13 g, 0.50 mmol of carbonate functionality), TBD (1,5,7-triazabicyclo [4.4.0] -dec-5-ene) (1.4 mg, 0.010 mmol) in 4 ml glass vials, Dimethylcarbonate (DMC) (1.0 mL), methanol (0.20 mL, 10 equiv), and hexamethylbenzene (13.8 mg, 0.085 mmol, internal standard) were added. The vial was placed in a preheating block at 50 ° C. After stirring for 6 hours, acetic acid was added to complete the reaction. Samples of the reaction mixture were subjected to 1 H-NMR analysis. Droplets of D ₂ O were added to the solution to remove the wide proton signal of phenol and residual water to improve accuracy. Yields of bisphenol A (BPA) (> 98%), bisphenol A monomethyl carbonate (BPAMC) (less than 1%) and bisphenol A dimethylcarbonate (BPADC) (not detected) were measured compared to hexamethylbenzene standards.

Example  2: polycarbonate decomposition ( depolymerization )

Polycarbonate decomposition was performed in the same manner as in Example 1 except that the reaction was carried out at 75 ° C. for 2 hours instead of the reaction at 50 ° C. for 6 hours.

Example  3: after use From polycarbonate  Bisphenol A Recovery

PC (1.3 g, 5.0 mmol of carbonate functionality), TBD (14 mg, 0.10 mmol), DMC (10 mL), and methanol (2.0 mL, 10 equiv) obtained from protective glasses (3M SeeproTM) in a 100 mL round bottom flask ). The flask was placed in a preheating block at 50 ° C. After stirring for 12 hours, the volatile chemicals were evaporated under reduced pressure and the solid mixture was purified by column chromatography (hexane / EtOAc from 5: 1 to 2: 1) to give BPA (1.1 g, 96%).

Example  4: TBD  Recovery and Recycling Experiment

1 cycle:

In a 25 mL round bottom flask was placed PC (0.51 g, 2.0 mmol of carbonate functionality), TBD (14 mg, 0.10 mmol), DMC (3.0 mL), and methanol (0.64 g, 20 mmol). The flask was placed in a preheating reaction block at 75 ° C. and after stirring for 2 hours, the reaction mixture was placed in an ice bath. 1,1,1-trichloroethane was added as an internal standard, a portion of the reaction mixture was taken to perform 1 H-NMR analysis, and the volatile components were evaporated under reduced pressure. . The solid mixture was dissolved in 20 ml of diethyl ether and the suspension was filtered and recovered. The diethyl ether solution was centrifuged to produce BPA (0.40 g, 88%).

2 cycles:

The solid containing TBD recovered in one cycle was mixed with PC (0.50 g, 2.0 mmol of carbonate functionality), DMC (3.0 mL), and methanol (0.64 g, 20 mmol) in a 25 mL round platter. After stirring for 2 hours, the reaction mixture was placed in an ice bath. 1,1,1-trichloroethane was added as internal standard and a portion of the reaction mixture was taken to perform 1 H-NMR analysis. The volatile components were evaporated under reduced pressure. The solid mixture was dissolved in diethyl ether (20 mL) and the suspension filtered and recovered. The diethyl ether solution was centrifuged to produce BPA (0.46 g in two cycles, 0.86 g total, 95% cumulative yield). The subsequent cycle can be performed in the same manner as the two cycles.

Example  5: TBD  catalyst in situ  Reuse experiment

In a 100 ml round bottom flask, PC (0.50 g, 2.0 mmol mmol of carbonate functionality), TBD (14 mg, 0.10 mmol), DMC (15 ml), methanol (4.0 ml) and hexamethylbenzene (0.14 g, 0.86 mmol) Added. The flask was placed on a reaction block preheated at 75 ° C. Reaction progress was monitored by 1 HNMR. After 45 minutes (BPA yield> 98% by 1 H-NMR), the reaction mixture was placed in an ice bath. A new portion of PC (0.52 g, 2.1 mmol carbonate functional group) was added to the reaction mixture. The resealed flask was placed in a 75 ° C. heating block and a second test was started. Each experiment is repeated following the same procedure.

Example  6: organic from polycarbonate decomposition Carbonate  synthesis

Poly (bisphenol A carbonate) (0.13 g, carbonate functional 0.50 mmol), 1-phenylethane-1,2-diol (0.35 g, 2.5 mmol) in 4 ml glass vials and 1,5,7-TBD (1.4 mg, 2.0 mol%) was dissolved in 2-methyltetrahydrofuran (1 mL). The mixture was stirred at 30 ° C. for 12 h, then the reaction was stopped by addition of some acetic acid and the crude mixture was purified directly by flash chromatography on silica gel (hexane / EtOAc 9: 1 to 3: 1) to BPA (113 mg, 99%) and 4-phenyl-1,3-dioxolan-2-one (76 mg, 92%) were obtained.

[Test Example]

Test Example  1: according to catalyst PC  Degradation rate and yield measurement

A series of catalysts known to exhibit high reactivity in transesterification is shown in FIG. 2. To 2-methyltetrahydrofuran (2-Me-THF), a polycarbonate solution (Mn = 21.0 kg / mol, Mw = 41.5 kg / mol, PDI = 1.98) and methanol (10 equiv) were added at room temperature. After 12 hours, the rate of decomposition and product yield were measured by 1 H-NMR spectroscopy and hexamethylbenzene was used as internal standard. Yields of monomer product, bisphenol A and BPA-dimethylcarbonates (BPADC), and BPA-mono-methylcarbonate (BPAMC) were measured and 1H-NMR spectra of BPA, BPADC and BPAMC were measured. Each component in the reaction mixture was analyzed using a dimethyl peak in the bisphenol A portion in comparison with. Schemes in which BPA, BPADC, and BPAMC are produced are shown in Scheme 1 below, and the yields according to catalysts and solvents are shown in Table 1 below. In Table 1, PC (0.5 mmol based on BPA unit), methanol (2.5 mmol) and catalyst (0.010 mmol, 2.0 mol%) were reacted with a solvent (1 mL) for 12 hours. b is measured by 1H-NMR spectroscopy on CDCl ₃ using hexamethylbenzene as internal standard, c is t-butanol as internal standard, d is 6 hours, e is 2 hours to be.

 Scheme 1

In this experiment, Ti (O i Pr) ₄ , p- toluenesulfonic acid (p-TSA), 4-dimethylaminopyridine (DMAP), sodium hydroxide and potassium hydroxide were used as the conventional esterification catalyst. However, the popular transesterification catalysts Ti (O i Pr) ₄ and TsOH did not show any activity (Experiment 1, Experiment 2). In the reaction with DMAP, a detectable level of phenolic terminal peak growth was observed at a detectable level in the 1 H-NMR spectrum and the molecular weight was reduced. However, the reaction rate was very slow (Experiment 3).

Alkali metals widely used in conventional polycarbonate decomposition showed excellent efficiency as expected. Sodium hydroxide completely degraded polycarbonate into a mixture of monomers consisting of 85% BPA and 15% BPAMC (Experiment 4). Only traces of BPADC were observed in the 1 H-NMR spectrum. Dimethyl carbonate (84%) was also recorded in high yield. Potassium hydroxide was better than sodium hydroxide (Experiment 5). Zn (TAC), a zinc cluster catalyst developed by Oshima, showed excellent transesterification efficiency over a wide range of esters. However, Zn (TAC) showed a low reaction rate in polycarbonate degradation (Experiment 6).

Then, an organic catalyst including DBU (1,8-diazabicyclo [5.4.0] undec-7-ene) and TBD was observed. These amidines and guanidine bases can catalyze the ring-opening polymerization of lactides and related cyclic esters to produce biodegradable polyesters. On the contrary, it is also possible to decompose the ester comprising the polymer. Polyethylene terephthalate and polylactic acid can be broken down into small molecules of synthetic value by transesterification with DBU and TBD.

However, their use in polycarbonate degradation has not been reported until recently. DBU was evaluated for conventional PC degradation, but in excess MeOH, high levels of BPA and DMC recovery were achieved. In this experiment, DBU and TBD showed excellent depolymerization efficiency with only 2mol% loading at room temperature. The reaction with DBU produced only monomeric products containing 40% BPA and 35% DMC at room temperature, leaving no polymeric or oligomeric residue. In addition, TBD showed good catalytic performance, with complete degradation to BPA (> 98%) and DMC (> 98%) without any other product notable to achieve complete degradation to the original monomers (Experiment 8).

Compared with the above systems where excess methanol was used, the addition of solvents compatible with PC (2-Me-THF) dramatically accelerated the degradation. From a process point of view, however, the use of auxiliary solvents requires a separate separation step after the reaction, which may result in additional investment and process costs.

Methanol and dimethylcarbonate were tested as solvents to reduce the number of species present in the system (Experiments 9-15). Poor solubility of polycarbonates in methanol hinders catalytic conversion (Experiment 9), but efficient polycarbonate degradation into monomeric species has been achieved in DMC (item 10). Complete degradation for BPA was achieved within 6 hours at 50 ° C. (Exp. 11, Example 1) and within 2 hours at 75 ° C. (Exp. 12, Example 2).

Comparing other organic catalysts in DMC solvents, DBU and 7-Methyl-1,5,7-triazabicyclo [4.4.0] dec-5-ene (MTBD) were less effective than TBD. DBU and MTBD showed similar performance regardless of the difference of basicity (Experiment 13, 14). The optimum amount of methanol was 10 equivalents. Low methanol loading reduced BPA and DMC production (Experiments 11, 15).

Thus, after decomposition, only three components are present, BPA, methanol and DMC, after which a simple purification process design can be expected. For reference, a process of separating methanol and DMC may be performed by a melt polymerization process of Asahi Kasei.

Experimental Example  2: Decomposition of polycarbonate after use

Chemical degradation of the PC was performed after use according to Example 3 and a photograph thereof is shown in FIG. 3. According to this, polycarbonate recovered from the protective eyewear was provided for TBD catalysis in DMC and high BPA (96%) recovery was achieved.

On the other hand, TBD-mediated methanolysis of PC in DMC (dimethylcarbonate) solvent was followed (50?) By the formation of phenolic aromatic (6.6-7.4 ppm) and dimethyl (1.6-1.7 ppm) peaks in 1 H-NMR. Is shown in FIG. 4. According to this, most of the polymerizable carbonate residues degraded into monomeric and oligomeric species within 20 minutes. Complete disappearance of the oligomer was achieved after 1 hour methanol digestion in DMC solvent, 50 ° C. Although BPDC completely transformed into BPAMC within 2 hours, the final step from BPAMC to BPA progressed slowly. Complete degradation to BPA was completed after 5 hours.

Test Example  3: TBD  Recyclability of the Catalyst

After performing a recycling experiment according to the method of Example 4, the recycling potential of the TBD catalyst was investigated and shown in Table 2 below. Specifically, after decomposition, the reaction mixture was washed with diethyl ether. The collected diethyl ether solution was evaporated to yield BPA, which gave a solid residue which was a mixture of BPA and TBD in the next cycle. The first cycle was performed with 5 mol% TBD loading. Complete BPA formation was observed at 75 ° C. in up to 3 cycles, 2 hours. Part of BPAMC was detected from cycle 4 (0.6% at 4 cycles and 3.0% at 5 cycles). The absence of TBD during the recycle process can reduce the catalyst efficiency.

cycle BPA yield (%) BPAMC (%) BPA (% cumulative) One 88 0 88 2 102 0 95 3 100 0 97 4 96 One 96 5 101 3 97

Reuse of the catalyst without recovery was also shown in Table 3 below.

cycle Time (h BPAMC (%) Cumulative BPA Yield (%) One 88 0 98 2 102 0 97 3 100 0 95 4 96 One 99 5 101 3 97

The reaction started with 15 ml DMC, 0.50 g of PC (2.0 mmol carbonate), 4.0 ml of methanol (0.10 mol, 50 equiv) and 0.14 g of TBD (5 mol%) at 75 ° C. When more than 95% BPA was formed by 1 H-NMR monitoring, more new PCs were added. TBD maintained its activity for up to 5 cycles and successfully degraded the PC to BPA. However, a signal of decreasing catalytic activity was detected and the time for complete degradation was getting longer every cycle. Given the acid-base equilibrium between BPA and TBD, the accumulation of BPA after each cycle will shift the equilibrium towards TBD-H ⁺ , which will result in lowering the concentration of active TBD.

Test Example  4: TBD -Catalyst mechanism analysis

In order to elucidate the mechanism by which TBD-catalyzed degradation of polycarbonates, experiments were conducted on carbonate activation.

To this end, a 1 H-NMR experiment of an organic catalytic reaction with diphenyl carbonate (DPC) was performed. In a 4 mL vial, DPC (0.021 g, 0.10 mmol) and TBD (14 mg, 0.10 mmol) were added to CDCl ₃ (1.0 mL). After 1 hour at ambient temperature, the reaction mixture was transferred to a 5 mm NMR tube and 1 H-NMR analysis was performed and the results are shown in FIG. 5.

According to this, equimolar amounts of diphenol carbonate (DPC) and organic bases (TBD, MTBD and DBU) were mixed in CDCl ₃ and phenol vitrification from DPC was monitored by 1 H-NMR after 1 hour. A 10-fold increase in basicity from DBU (pKa = 24.3 conjugated acid at CH ₃ CN) to MTBD (pKa = 25.5, conjugated acid at CH ₃ CN) showed no difference in the rate of carbamate production. The results were consistent with the results (Experiments 13 and 14 in Table 1). However, TBD (pKa = 26.0, conjugate in CH ₃ CN) showed 64% phenolate formation. The nucleophilicity in a given organic base did not significantly affect the rate of degradation, and it is assumed that TBD did not act only as a general base catalyst.

Meanwhile, PC (0.13 g, 0.50 mmol) and TBD (1.4 mg, 0.010 mmol, 2 mol%) were mixed in CHCl ₃ (10 mL) in a 20 mL vial. After 1 hour at ambient temperature, the aliquots of the reaction mixture were analyzed by GPC. The results are shown in FIG. 6. According to this, carbonate group activation and carbamate formation by organic bases will result in chain cleavage resulting in a decrease in molecular weight. Reaction with polycarbonate showed no signs of degradation. The stronger base, MTBD, slightly degraded the PC and formed a small amount of oligomer product. On the other hand, guanidine catalyst TBD showed significant degradation along with low molecular weight products.

This result supports the nucleophilic addition pathway shown on the left side of FIG. 7, one of the valid degradation reaction mechanisms. TBD showed excellent activity in the first stage of carbamate intermediate formation. The next step, the addition of alcohol to carbamate, is expected to be facilitated by hydrogen bond activation between TBD and the incoming alcohol. Hydrogen bonding activity pathways are another possible mechanism proposed in TBD-mediated lactide polymerization and poly (ethyleneterephthalate) degradation.

Simultaneous activation of carbonates and alcohols by imine and amine residues in TBD can promote polycarbonate degradation. In both reaction pathways, the donor and acceptor properties of guanidine functional groups in TBD play an important role in promoting the decomposition of polycarbonates that other catalysts, DBU and MTBD, do not have.

Test Example  5: organic by alcohol type Carbonate

Organic carbonates are a class of compounds used in many applications. Many methods of preparation have been developed and the active carbonyl compounds comprising toxic phosgene and derivatives thereof, or CO ₂ and epoxides are mainly used as starting materials. In this test, the TBD-catalyst decomposition produced a range of organic carbonates from polycarbonate waste according to various alcohols, and the results are shown in Table 4 below.

Using a TBD catalyst (2 mol%) in 2-Me-THF, the alcohol tested successfully degraded the polycarbonate to produce BPA and the corresponding carbonate in high yield. Both linear and cyclic carbonates were readily synthesized into polycarbonate resins. While 1,2-diol with steric bulky substituents did not inhibit the reaction rate (Experiment 5-7), the conversion from methanol to ethanol showed low conversion (Experiment 2, BPA 71%, 72% carbonate at 50 ° C). ). These results show that depending on the choice of alcohol in the decomposition of PC, it can be recycled to more valuable organic carbonates. Compared with producing organic carbonates from current phosgene or epoxide / CO ₂ , it has been found that the PC recycling route of the present invention can be carried out simply and safely.

As described above, embodiments of the present invention have been described, but those skilled in the art may add, change, delete, or add elements within the scope not departing from the spirit of the present invention described in the claims. The present invention may be modified and changed in various ways, etc., which will also be included within the scope of the present invention.

Claims (11)

Guanidine derivatives for catalysts used in alcohol decomposition reactions to decompose polycarbonates into bisphenol A and organic carbonates. The method of claim 1,
The catalyst guanidine derivative is a catalyst guanidine derivative, characterized in that represented by the following structural formula 1;
[Formula 1]

In structure 1,
R ¹ and R ² are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group, or R ¹ and R ² are bonded to each other and substituted or unsubstituted with 3 atoms therebetween To form a C1 to C30 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C30 heteroaryl group,
R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group,
X is

or

ego,
R ⁵ to R ⁷ are the same as or different from each other, and each independently a hydrogen atom, a substituted or unsubstituted C1 to C30 alkyl group, or a substituted or unsubstituted C3 to C30 cycloalkyl group, a substituted or unsubstituted C1 to C30 heterocycloalkyl group , A substituted or unsubstituted C6 to C30 aryl group, or a substituted or unsubstituted C1 to C30 heteroaryl group. The method of claim 2,
In the above formula 1,
R ¹ and R ² combine with each other to form a substituted or unsubstituted fused C1 to C5 heterocycloalkyl group, or a substituted or unsubstituted fused C1 to C5 heteroaryl group with three atoms therebetween,
R ³ and R ⁴ are the same as or different from each other, and each independently a hydrogen atom or a substituted or unsubstituted C1 to C10 alkyl group,
X is

ego,
R ⁵ is a hydrogen atom, or a guanidine derivative for a catalyst, characterized in that a substituted or unsubstituted C1 to C10 alkyl group. The method of claim 1,
The guanidine derivative is a catalyst guanidine derivative, characterized in that TBD (1,5,7-triazabicyclo [4.4.0] -dec-5-ene). Guanidine derivatives A method of decomposing a polycarbonate, comprising: alcohol (poly (bisphenol A carbonate)) to bisphenol A and carbonate (alcoholysis) under an organic catalyst and alcohol conditions. The method of claim 5,
The guanidine derivative is a decomposition method of polycarbonate, characterized in that the loading of 0.01 to 5 mol% with respect to the polycarbonate. The method of claim 5,
The solvent used in the alcohol decomposition is a decomposition method of polycarbonate, characterized in that the same organic carbonate as the organic carbonate produced according to the type of alcohol after alcohol decomposition. The method of claim 5,
The alcohol used in the alcohol decomposition is a method of decomposing polycarbonate, characterized in that methanol. The method of claim 8,
The solvent used for alcohol decomposition is dimethyl carbonate, characterized in that the decomposition method of polycarbonate. The method of claim 5,
After the alcohol decomposition, further comprising the step of dissolving the solid mixture produced by evaporation of the volatiles in an organic solvent and filtering the suspension to recover the organic catalyst. The method of claim 10,
The recovered catalyst may be reused once or multiple times for the decomposition of the polycarbonate.

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