JP4871616B2 - Method for inhibiting polymerization of aromatic vinyl compound - Google Patents

Description

  The present invention relates to a method for suppressing polymerization of an aromatic vinyl compound or a process fluid containing the aromatic vinyl compound in a process for producing, purifying, storing or transporting an aromatic vinyl compound.

Aromatic vinyl compounds, particularly styrene, are very important compounds in the industry as raw materials for producing polystyrene, synthetic rubber, ABS resin and the like, and are industrially produced in large quantities.
In general, aromatic vinyl compounds are extremely easy to polymerize, and easily polymerize due to factors such as the addition of heat in the manufacturing or purification process, reducing the yield of aromatic vinyl compound monomers, and fouling ( There is a problem that the operation of the equipment is hindered. As a countermeasure, a method of adding a polymerization inhibitor into the process stream has been proposed and put into practical use. For example, a method using phenol, nitrosophenol, nitrophenol (for example, see Patent Document 1), a method using piperidine-1-oxyl (for example, see Patent Document 2), or a combination of nitrophenols and piperidineoxyls A method using a combination of an alkyl sulfonic acid and a dialkylhydroxylamine (for example, see Patent Document 4), a method using a combination of a phosphate ester and an alkyl sulfonic acid (for example, a patent document) 5), a method of adding a phenol-based, amine-based, nitroso-based polymerization inhibitor, dodecylbenzenesulfonic acid and its salt in order to suppress an increase in viscosity in the olefin production process (for example, see Patent Document 6), vinyl compound To prevent fouling in the handling process Non-based, hydroquinone-based, nitroso-based, a method of adding an amine-based polymerization inhibitor and dodecylbenzenesulfonic acid and salts thereof such as phenylenediamine (e.g., see Patent Document 7) have been proposed. Among these, nitrophenols such as 2,6-dinitrophenol (DNP), 2,6-dinitro-4-methylphenol, and 2,4-dinitro-6-secondary butylphenol (DNBP) are polymerization inhibitors of aromatic vinyl compounds. It is often used as. However, these chemicals show a tendency to gradually reduce the inhibitory power of the polymerization reaction, and are toxic, so that strict handling is required. Therefore, there has been a strong demand for a method that can maintain the polymerization-inhibiting effect of these drugs and reduce the amount used.

Japanese Unexamined Patent Publication No. Sho 63-316745 JP-A-1-165534 JP-A-6-166636 US Pat. No. 4,654,450 U.S. Pat. No. 4,425,223 JP 7-166152 A JP-A-8-34748

  Therefore, the present invention not only suppresses the initial polymerization in the production, purification, storage or transportation process of the aromatic vinyl compound, but also efficiently suppresses the polymerization over a long period of time and is excellent in handleability. It aims at providing the polymerization suppression method of an aromatic vinyl compound.

  As a result of examining the characteristics of the polymerization reaction of the vinyl compound in detail, the present inventors have used a specific nitrogen-containing aromatic compound and a sulfonic acid compound in combination, thereby suppressing polymerization compared to when they are used alone. The inventors have found that an excellent synergistic effect is achieved, and have made the present invention. That is, the present invention includes the following contents.

That is, in the first aspect of the present invention, in the process of producing, purifying, storing or transporting an aromatic vinyl compound, (A) a nitrogen-containing aromatic compound represented by the general formula (I) (wherein R ₁ , R _2, R ₃ , R ₄ , R ₅ and R ₆ are each independently a hydrogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkenyl group having 2 to 12 carbon atoms, carbon An aryl group having 6 to 14 aryl groups, an amino group, an alkyl-substituted amino group having at least one linear or branched alkyl group having 1 to 12 carbon atoms, or an aryl-substituted amino having at least one aryl group having 6 to 14 carbon atoms R ₁ and R ₂ , R ₃ and R ₄ , R ₄ and R ₅ or R ₅ and R ₆ may be bonded to each other to form an alicyclic or aromatic ring structure. ) And (B) a sulfonic acid compound represented by the general formula (II) (wherein R is a hydroxyl group, a linear or branched alkyl group having 1 to 32 carbon atoms, a linear or branched alkyl group having 1 to 32 carbon atoms) An alkyl-substituted phenyl group having at least one group or an alkyl-substituted naphthyl group) is added.

  In the second aspect of the present invention, the nitrogen-containing aromatic compound represented by the general formula (I) is phenazine, 2-methylphenazine, 2-ethylphenazine, quinoxaline, 2-methylquinoxaline, 2-phenylquinoxaline, 3-amino- A method for inhibiting polymerization of an aromatic vinyl compound, which is at least one selected from the group consisting of 7-hydroxy-2-methylphenazine and tetrabenzo [a, c, h, j] tetrabenzophenazine.

  In the third aspect of the present invention, the sulfonic acid compound represented by the general formula (II) is selected from toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid and dinonylnaphthalenesulfonic acid. A method for inhibiting polymerization of an aromatic vinyl compound, characterized in that it is at least one selected from the group consisting of:

  A fourth aspect of the present invention is a fragrance characterized by adding a nitrogen-containing aromatic compound as component (A) and a sulfonic acid compound as component (B) in a weight ratio in the range of 5:95 to 95: 5. This is a method for inhibiting polymerization of an aromatic vinyl compound.

  According to the present invention, the polymerization of the aromatic vinyl compound or the process fluid containing the same is efficiently suppressed, and the effect is maintained for a long time. Therefore, the amount of fouling (dirt) in the related apparatus is minimized, and the equipment Advantages such as safe driving and greatly contributing to production cost reduction can be enjoyed.

The nitrogen-containing aromatic compound represented by the general formula (I) of the component (A) in the present invention has a benzopyrazine skeleton, and R ₁ , R ₂ , R ₃ , R ₄ , R ₅ and R ₆ are each independently Hydrogen atom, hydroxyl group, linear or branched alkyl group having 1 to 12 carbon atoms, linear or branched alkenyl group having 2 to 12 carbon atoms, aryl group having 6 to 14 carbon atoms, amino group, from 1 carbon atom An alkyl-substituted amino group having at least one straight-chain or branched alkyl group of 12 or an aryl-substituted amino group having at least one aryl group having 6 to 14 carbon atoms; R ₁ and R ₂ , R ₃ and R ₄ , R ₄ and R ₅ or R ₅ and R ₆ may be bonded to each other to form an alicyclic or aromatic ring structure. Specific compounds include, for example, quinoxaline, 2-methylquinoxaline, 2-ethylquinoxaline, 2-phenylquinoxaline, 2-hydroxyquinoxaline, 2-aminoquinoxaline, 2-dimethylaminoquinoxaline, dibenzopyrazine (phenazine), 3- Amino-7-hydroxy-2-methylphenazine, tetrabenzo [a, c, h, j] phenazine and the like can be mentioned.

  In the present invention, the sulfonic acid compound represented by the general formula (II) of the component (B) used in combination with the nitrogen-containing aromatic compound of the component (A) is a compound in which R is a hydroxyl group and has 1 to 32 carbon atoms. A sulfonic acid compound which is an alkyl-substituted phenyl group having at least one linear or branched alkyl group having 1 to 32 carbon atoms or an alkyl-substituted naphthyl group, and one or more of these To be elected. Specific examples of the sulfonic acid compound include sulfuric acid, toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and the like. Pentadecyl sulfonic acid and dodecyl benzene sulfonic acid are more preferable from the viewpoint of solubility and price.

  In the present invention, a nitrogen-containing aromatic compound and a sulfonic acid compound are combined and added to the process of producing, purifying, storing or transporting the aromatic vinyl compound, and the mixing ratio of the two can be arbitrarily selected, but a synergistic effect is achieved. The nitrogen-containing aromatic compound and the sulfonic acid compound are mixed in a weight ratio of 95: 5 to 5:95, preferably 80:20 to 20:80, more preferably 70:30 to 30:70.

  The amount of nitrogen-containing aromatic compound and sulfonic acid compound added to the process varies depending on the conditions of the target process, the degree of polymerization inhibition, etc., and is not uniformly determined, but is generally the target The nitrogen-containing aromatic compound is 1 to 3000 ppm, preferably 10 to 2000 ppm, more preferably 100 to 1000 ppm, and the sulfonic acid compound is 1 to 3000 ppm, preferably 10 to 2000 ppm, more preferably 100 to 1000 ppm with respect to the aromatic vinyl compound. It is. These addition amounts are found as a suitable range for exhibiting the polymerization inhibiting effect of the target aromatic vinyl compound, and if it is smaller than this range, the effect is not sufficient, and from this range, At most, the effect is sufficient, but the effect does not increase with respect to the amount added, and may not be preferable from an economic standpoint.

  In the present invention, the place where the nitrogen-containing aromatic compound and the sulfonic acid compound are added to the step is not particularly limited, but usually upstream from the place where the aromatic vinyl compound is polymerized and becomes a problem as fouling. Add to the process. For example, styrene is generally produced by a dehydrogenation reaction of ethylbenzene, and the produced styrene and unreacted ethylbenzene are continuously separated by distillation, and thus supplied to a distillation column group after the ethylbenzene dehydrogenation.

  In the present invention, the method for adding the nitrogen-containing aromatic compound and the sulfonic acid compound to the step is not particularly limited, but it is usually added to a specific location at once, or divided into several locations, A method such as dispersion addition is appropriately selected. At this time, the nitrogen-containing aromatic compound and the sulfonic acid compound can be added separately, but they are dissolved in the same liquid as the process fluid in an appropriate mixing ratio, such as ethylbenzene or crude styrene in the case of styrene. Is practically convenient to add.

  In the present invention, in addition to the nitrogen-containing aromatic compound and the sulfonic acid compound, there is no limitation to using other known polymerization inhibitors in combination as long as the effects of the present invention are not impaired.

  The present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples.

[Nitrogen-containing aromatic compounds]
A-1: quinoxaline A-2: 1-methylquinoxaline A-3: phenazine A-4: 3-amino-7-hydroxy-2-methylphenazine A-5: tetrabenzo [a, c, h, j] phenazine

[Sulfonic acid compound]
B-1: Dodecylbenzenesulfonic acid
B-2: Pentadecylbenzenesulfonic acid B-3: Xylenesulfonic acid
B-4: cumenesulfonic acid B-5: p-toluenesulfonic acid B-6: methanesulfonic acid B-7: sulfuric acid (98%)

[Others]
DNBP: 2,4-dinitro-6-sec-butylphenol H-TEMPO: 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl

[Polymerization inhibition test-1]
Into a four-necked separable flask equipped with a reflux condenser, 100 g of styrene monomer is added, a predetermined amount of a polymerization inhibitor shown in Table 1 is added (the mixing ratio of each drug is shown below), and high-purity nitrogen gas is added for 30 minutes. The dissolved oxygen was removed by blowing. Next, this was maintained at 120 ° C., and a part of the contents was taken out at regular intervals and sampled, and the amount of polymer produced (ppm) in the liquid was measured. 9 times the volume of the sampling solution of methanol was added to precipitate the polymer in a suspended state in the solution, filtered and the polymer weight was weighed to determine the amount of polymer produced in the monomer. Before starting this experiment, the styrene monomer was washed with alkali to remove the polymerization inhibitor (t-butylcatechol) contained in the monomer, washed with water and dried. The obtained results are shown in Table 1.

  From the results shown in Table 1, the nitrogen-containing aromatic compound and the sulfonic acid compound each show only a polymerization inhibitory effect, but by combining them, a synergistic effect is exhibited, and the polymerization inhibitory effect over a long period of time. It will be understood that this will last.

Claims (4)

In the process of producing, purifying, storing or transporting an aromatic vinyl compound, (A) a nitrogen-containing aromatic compound represented by the general formula (I) (wherein R ₁ , R _2, R ₃ , R ₄ , R ₅ , R ₆ each independently represents a hydrogen atom, a hydroxyl group, a linear or branched alkyl group having 1 to 12 carbon atoms, a linear or branched alkenyl group having 2 to 12 carbon atoms, an aryl group having 6 to 14 carbon atoms, amino A group, an alkyl-substituted amino group having at least one linear or branched alkyl group having 1 to 12 carbon atoms or an aryl-substituted amino group having at least one aryl group having 6 to 14 carbon atoms, R ₁ and R ₂ , R ₃ and R ₄ , R ₄ and R _5, or R ₅ and R ₆ may be bonded to each other to form an alicyclic or aromatic ring structure) and (B) the general formula (II ) (Wherein R is a hydroxyl group, a linear or branched alkyl group having 1 to 32 carbon atoms, an alkyl-substituted phenyl group having at least one linear or branched alkyl group having 1 to 32 carbon atoms, or A method for inhibiting polymerization of an aromatic vinyl compound, which comprises adding an alkyl-substituted naphthyl group.

The nitrogen-containing aromatic compound represented by the general formula (I) is phenazine, 2-methylphenazine, 2-ethylphenazine, quinoxaline, 2-methylquinoxaline, 2-phenylquinoxaline, 3-amino-7-hydroxy-2- The method for inhibiting polymerization of an aromatic vinyl compound according to claim 1, which is at least one selected from the group consisting of methylphenazine and tetrabenzo [a, c, h, j] tetrabenzophenazine. The sulfonic acid compound represented by the general formula (II) is at least one selected from the group consisting of toluenesulfonic acid, xylenesulfonic acid, cumenesulfonic acid, dodecylbenzenesulfonic acid, pentadecylbenzenesulfonic acid and dinonylnaphthalenesulfonic acid. The method for inhibiting polymerization of an aromatic vinyl compound according to claim 1 or 2, which is a seed. The fragrance according to any one of claims 1 to 3, wherein the nitrogen-containing aromatic compound as component (A) and the sulfonic acid compound as component (B) are added in combination in a weight ratio of 5:95 to 95: 5. For inhibiting polymerization of an aromatic vinyl compound.