Preparation method of thiomethylphenol derivatives

Abstract

The present invention discloses a method for preparing a thiomethylphenol derivative, which comprises: step (a), in the presence of a heterocyclic base having 3 to 10 carbon atoms and an acid, a phenol derivative represented by the following chemical formula 2, a thiol derivative represented by R4SH and polyformaldehyde are reacted at a reaction temperature T1; and step (b), a secondary reaction is carried out at a reaction temperature T2, thereby preparing a thiomethylphenol derivative represented by the following chemical formula 1, wherein the preparation method of the thiomethylphenol derivative satisfies T1 <T2。

Description

Technical Field

[0001] The invention relates to a method for preparing a thiomethylphenol derivative. Background Art

[0002] Thiomethylphenol derivatives are used as antioxidants in plastics, rubbers, and oils.

[0003] These thiomethylphenol derivatives are produced by reacting a phenol derivative with paraformaldehyde and a thiol derivative in the presence of a catalyst, but the reaction temperature is too high or the reaction time is too long, and various methods for improving these problems have been tried.

[0004] For example, methods of conducting a reaction in the presence of a base or using a reducing agent have been proposed, but there are problems such as a long purification time and discoloration during the reaction and purification process.

[0005] Korean Patent Nos. 813173, 813174, 926796, 963311, etc. propose methods of reducing discoloration by conducting a reaction in the presence of a base and an acid and purifying with an acid. Summary of the invention

[0006] Technical issues

[0007] The present invention aims to provide a method for preparing thiomethylphenol derivatives, which can further reduce the discoloration of the final product, improve the stability, and enhance the environmental protection of the purification process and the energy efficiency of the entire process.

[0008] Technical Solution

[0009] According to one aspect, a method for preparing a thiomethylphenol derivative is provided, the method comprising: step (a), in the presence of a heterocyclic base having 3 to 10 carbon atoms and an acid, reacting the base at a reaction temperature T 1 The phenol derivative represented by the following chemical formula 2, R 4 SH represents a thiol derivative and paraformaldehyde to react once; and step (b), at a reaction temperature T 2 The secondary reaction is carried out under the following conditions to prepare a thiomethylphenol derivative represented by the following chemical formula 1, wherein the preparation method of the thiomethylphenol derivative satisfies T 1 <T 2 .

[0010] [Chemical formula 1]

[0011]

[0012] [Chemical formula 2]

[0013]

[0014] In the formula, R 1 and R 2 are each independently selected from hydrogen, deuterium, C 1 ~C 16 Straight or branched alkyl, C 5 ~C 16 Cycloalkyl or arylalkyl and -CH 2 SR 3 In, R 3 and R 4 Each selected from C 1 ~C 16 Straight or branched alkyl, C 5 ~C 16 In a cycloalkyl group or an aralkyl group, R 11 and R 22 are each independently selected from hydrogen, deuterium, C 1 ~C 16 Straight or branched alkyl, C 5 ~C 16 In the cycloalkyl group or the arylalkyl group, n is 0 or 1.

[0015] In one embodiment, the preparation method of the thiomethylphenol derivative can meet the requirements of 95°C <T 1 +5℃≤T 2 <120℃.

[0016] In one embodiment, the above steps (a) and (b) can be performed for 1 hour to 5 hours respectively.

[0017] In one embodiment, the step (a) may be performed in the presence of 0.5 to 50.0 equivalents of a solvent relative to 1 equivalent of the phenol derivative.

[0018] In one embodiment, the solvent may be water or alcohol.

[0019] In one embodiment, in the step (a), 0.01 to 0.50 equivalents of the base may be used relative to 1 equivalent of the phenol derivative.

[0020] In one embodiment, the base in step (a) may be at least one selected from the group consisting of pyrrole, pyrrolidine, imidazole, pyridine, piperidine, piperazine and pyrazine.

[0021] In one embodiment, in the step (a), 0.01 to 0.90 equivalents of the acid may be used relative to 1 equivalent of the phenol derivative.

[0022] In one embodiment, the acid in step (a) may be at least one selected from the group consisting of chlorous acid, phosphoric acid, arsenic acid, chloroacetic acid, hydrofluoric acid, nitrous acid, formic acid, benzoic acid, hydrazoic acid, acetic acid, propionic acid and carbonic acid.

[0023] In one embodiment, in the step (a), 2.0 to 6.0 equivalents of the thiol derivative may be used relative to 1 equivalent of the phenol derivative.

[0024] In one embodiment, in the step (a), 2.0 to 6.0 equivalents of paraformaldehyde may be used relative to 1 equivalent of the phenol derivative.

[0025] In one embodiment, after the step (b), a purification step (c) of washing the organic layer in the product of the step (b) with an acid may be further included.

[0026] In one embodiment, the pKa of the acid in step (c) may be greater than 2.0.

[0027] In one embodiment, the acid in step (c) may be at least one selected from the group consisting of chlorous acid, phosphoric acid, arsenic acid, chloroacetic acid, hydrofluoric acid, nitrous acid, formic acid, benzoic acid, hydrazoic acid, acetic acid, propionic acid and carbonic acid.

[0028] In one embodiment, after the above step (c), a step (d) of washing with alkali or water may be further included.

[0029] In one embodiment, the alkali may be at least one selected from the group consisting of anhydrous sodium carbonate, sodium percarbonate and sodium bicarbonate.

[0030] In one embodiment, after the above step (d), the method may further include performing reduced pressure concentration at a temperature of 90° C. to 120° C. for 1 to 5 hours to separate the thiomethylphenol derivative represented by Chemical Formula 1 (e).

[0031] In one embodiment, the APHA value of the separated thiomethylphenol derivative can be less than 75 after being placed at 120° C. for 72 hours.

[0032] Technical Effects

[0033] According to one aspect, a method for preparing a thiomethylphenol derivative can be provided, wherein the stability of the final product is improved, discoloration during the process is minimized, and the energy efficiency of the preparation process and the economy of the purification process are improved.

[0034] The effects of one aspect of the present specification are not limited to the effects described above, and should be understood to include all effects inferred from the structure of the invention described in the detailed description of the present specification or the scope of the claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A schematic diagram showing a method for preparing a thiomethylphenol derivative according to an embodiment of the present specification.

[0036] Embodiments of the invention

[0037] One aspect of the present specification will be described below with reference to the accompanying drawings. However, the matters described in the present specification can be implemented in many different forms and should not be construed as being limited to the embodiments described herein. In the accompanying drawings, in order to clearly illustrate one aspect of the present specification, parts that are not related to the description are omitted, and the same reference numerals always indicate the same components.

[0038] Throughout the specification, when it is stated that a certain part is "connected" to other parts, this includes not only the case of "direct connection" but also the case of "indirect connection" with other components arranged in between. Furthermore, when it is stated that a certain part "includes" a certain structural element, unless there is a special statement to the contrary, this means that other structural elements are not excluded but may be included.

[0039] In this specification, when describing a series of numerical ranges, unless otherwise specifically stated, these values ​​have a precision of significant figures provided according to standard rules in chemistry for significant figures. For example, 10 includes a range of 5.0 to 14.9, and the number 10.0 includes a range of 9.50 to 10.49.

[0040] Hereinafter, one embodiment of the present specification will be described in detail with reference to the accompanying drawings.

[0041] Preparation method of thiomethylphenol derivatives

[0042] According to one aspect, the preparation method of the thiomethylphenol derivative may include: step (a), in the presence of a heterocyclic base having 3 to 10 carbon atoms and an acid, at a reaction temperature T 1 The phenol derivative represented by the following chemical formula 2, R 4 SH represents a thiol derivative and paraformaldehyde to react once; and step (b), at a reaction temperature T 2 The secondary reaction is carried out under the following conditions to prepare a thiomethylphenol derivative represented by the following chemical formula 1, wherein the preparation method of the thiomethylphenol derivative can satisfy T 1 <T 2 .

[0043] [Chemical formula 1]

[0044]

[0045] [Chemical formula 2]

[0046]

[0047] In the formula, R 1 and R 2 are each independently selected from hydrogen, deuterium, C 1 ~C 16 Straight or branched alkyl, C 5 ~C 16 Cycloalkyl or arylalkyl and -CH 2 SR 3 In, R 3 and R 4 Each selected from C 1 ~C 16 Straight or branched alkyl, C 5 ~C 16 In a cycloalkyl group or an aralkyl group, R 11 and R 22 are each independently selected from hydrogen, deuterium, C 1 ~C 16 Straight or branched alkyl, C 5 ~C 16 In the cycloalkyl group or the arylalkyl group, n is 0 or 1.

[0048] Reference Figure 1 The preparation method of the thiomethylphenol derivative comprises the following steps: 1 A reaction carried out at a temperature higher than the temperature of the above-mentioned reaction 2 The secondary reaction carried out under the condition of being oxidized to a certain extent can improve the purity of the final product, and the thermal stability can be significantly improved by changing the composition of the by-products that may be partially contained.

[0049] The preparation method of the thiomethylphenol derivative can meet the requirements of 95°C <T 1 +5℃≤T 2 <120℃. When above T 1 When the temperature is below 90°C, the reaction may not proceed sufficiently. 2 When the temperature is 120°C or higher, the efficiency may be insufficient compared to the energy used. 1 and T 2 When the temperature difference between the two is 5°C or more, the above-mentioned purity improvement and thermal stability improvement can be effectively achieved.

[0050] The above steps (a) and (b) can be performed for 1 to 5 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours or a time range between any two of these values.

[0051] The phenol derivative may be at least one selected from the group consisting of o-cresol, p-cresol, 4-butylphenol, and bisphenol.

[0052] The step (a) can be carried out in the presence of 0.5 to 50.0 equivalents of a solvent relative to 1 equivalent of the phenol derivative, for example, 0.5 equivalents, 1.0 equivalents, 1.5 equivalents, 2.0 equivalents, 2.5 equivalents, 3.0 equivalents, 3.5 equivalents, 4.0 equivalents, 4.5 equivalents, 5.0 equivalents, 5.5 equivalents, 6.0 equivalents, 6.5 equivalents, 7.0 equivalents, 7.5 equivalents, 8.0 equivalents, 8.5 equivalents, 9.0 equivalents, 9.5 equivalents, 10.0 equivalents, 10.5 equivalents, , 11.0 equivalents, 11.5 equivalents, 12.0 equivalents, 12.5 equivalents, 13.0 equivalents, 13.5 equivalents, 14.0 equivalents, 14.5 equivalents, 15.0 equivalents, 15.5 equivalents, 16.0 equivalents, 16.5 equivalents, 17.0 equivalents, 17.5 equivalents, 18.0 equivalents, 18.5 equivalents, 19.0 equivalents, 19.5 equivalents, 20.0 equivalents, 20.5 equivalents, 21.0 equivalents, 21.5 equivalents, 22.0 equivalents, 22.5 equivalents, 23.0 equivalents, 23.5 equivalents, 24.0 equivalents, 24. 5 equivalents, 25.0 equivalents, 25.5 equivalents, 26.0 equivalents, 26.5 equivalents, 27.0 equivalents, 27.5 equivalents, 28.0 equivalents, 28.5 equivalents, 29.0 equivalents, 29.5 equivalents, 30.0 equivalents, 30.5 equivalents, 31.0 equivalents, 31.5 equivalents, 32.0 equivalents, 32.5 equivalents, 33.0 equivalents, 33.5 equivalents, 34.0 equivalents, 34.5 equivalents, 35.0 equivalents, 35.5 equivalents, 36.0 equivalents, 36.5 equivalents, 37.0 equivalents, 37.5 equivalents, 38.0 equivalents, The reaction mixture is carried out in the presence of a solvent in an amount of 38.5 equivalents, 39.0 equivalents, 39.5 equivalents, 40.0 equivalents, 40.5 equivalents, 41.0 equivalents, 41.5 equivalents, 42.0 equivalents, 42.5 equivalents, 43.0 equivalents, 43.5 equivalents, 44.0 equivalents, 44.5 equivalents, 45.0 equivalents, 45.5 equivalents, 46.0 equivalents, 46.5 equivalents, 47.0 equivalents, 47.5 equivalents, 48.0 equivalents, 48.5 equivalents, 49.0 equivalents, 49.5 equivalents, or 50.0 equivalents, or in the presence of a solvent in a range between any two of these values. When the content of the solvent exceeds the above range, the reactivity may be reduced.

[0053] The solvent may be water or alcohol. For example, the alcohol may be at least one selected from the group consisting of methanol, ethanol, propanol, isopropanol and butanol.

[0054] In the above step (a), 0.01 to 0.50 equivalents of the base can be used relative to 1 equivalent of the above phenol derivative, for example, 0.01 equivalents, 0.05 equivalents, 0.10 equivalents, 0.15 equivalents, 0.20 equivalents, 0.25 equivalents, 0.30 equivalents, 0.35 equivalents, 0.40 equivalents, 0.45 equivalents, 0.50 equivalents or bases in the range between any two of these values ​​can be used relative to 1 equivalent of the above phenol derivative. When the amount of the above base used is too small, the reaction time becomes unnecessarily long, and when the amount of the above base used is too large, the product characteristics may be deteriorated due to by-products.

[0055] The heterocyclic base is a cyclic alkane, a cyclic alkene, a cyclic alkyne or an aromatic hydrocarbon in which at least one of the constituent carbon atoms is converted into a heteroatom. As an example, the heterocyclic base in the step (a) can be at least one selected from the group consisting of pyrrole, pyrrolidine, imidazole, pyridine, piperidine, piperazine and pyrazine.

[0056] In the above step (a), the acid can be used in an amount of 0.01 to 0.90 equivalents relative to 1 equivalent of the above phenol derivative, for example, 0.01 equivalents, 0.05 equivalents, 0.10 equivalents, 0.15 equivalents, 0.20 equivalents, 0.25 equivalents, 0.30 equivalents, 0.35 equivalents, 0.40 equivalents, 0.45 equivalents, 0.50 equivalents, 0.55 equivalents, 0.60 equivalents, 0.65 equivalents, 0.70 equivalents, 0.75 equivalents, 0.80 equivalents, 0.85 equivalents, 0.90 equivalents or an acid in a range between any two of these values ​​can be used relative to 1 equivalent of the above phenol derivative. When the amount of the acid used in the above step (a) satisfies the above range, the reaction temperature and time conditions may be more favorable.

[0057] The acid in step (a) may be at least one selected from the group consisting of chlorous acid, phosphoric acid, arsenic acid, chloroacetic acid, hydrofluoric acid, nitrous acid, formic acid, benzoic acid, hydrazoic acid, acetic acid, propionic acid and carbonic acid.

[0058] As an example, when the above step (a) is carried out in the presence of a heterocyclic base and an acid, the base and paraformaldehyde as reactants form an ammonia methanol intermediate, which is converted into an imine with greater reactivity by the acid, thereby maximizing the reactivity with phenol and preventing oxidation of the base. In addition, compared with a straight-chain base, a heterocyclic base minimizes interference with the space for intermolecular reaction, thereby increasing the reaction rate.

[0059] In the above step (a), 2.0 to 6.0 equivalents of the thiol derivative can be used relative to 1 equivalent of the phenol derivative. For example, 2.0 equivalents, 2.5 equivalents, 3.0 equivalents, 3.5 equivalents, 4.0 equivalents, 4.5 equivalents, 5.0 equivalents, 5.5 equivalents, 6.0 equivalents, or a range between any two of these values ​​can be used relative to 1 equivalent of the phenol derivative. When the amount of the thiol derivative used is too small, a mixture of, for example, monothiomethylphenol and dithiomethylphenol may be generated due to unreaction, and when the amount of the thiol derivative used is too large, by-products may increase and the purification time may be unnecessarily prolonged.

[0060] The thiol derivative may be at least one selected from the group consisting of octanethiol, decanethiol, dodecanethiol, benzylthiol, and thiophenol.

[0061] In the above step (a), 2.0 to 6.0 equivalents of paraformaldehyde may be used relative to 1 equivalent of the above phenol derivative, for example, 2.0 equivalents, 2.5 equivalents, 3.0 equivalents, 3.5 equivalents, 4.0 equivalents, 4.5 equivalents, 5.0 equivalents, 5.5 equivalents, 6.0 equivalents, or paraformaldehyde in a range between any two of these values. When the amount of the above paraformaldehyde used is too small, a mixture of, for example, monothiomethylphenol and dithiomethylphenol may be generated due to unreaction, and when the amount of the above paraformaldehyde used is too large, the purification time may be unnecessarily prolonged.

[0062] After the above step (b), a purification step (c) of washing the organic layer in the product of the above step (b) with an acid may be further included. In the above organic layer, in addition to the thiomethylphenol derivative, ammonia methanol and the like as reaction intermediates remain, causing discoloration of the final product. Therefore, in addition to the above two-step reaction, the discoloration may be minimized by purification by decomposing or removing ammonia methanol with a certain amount of acid.

[0063] The pKa of the acid in step (c) may be greater than 2.0, and may be, for example, at least one selected from the group consisting of chlorous acid, phosphoric acid, arsenic acid, chloroacetic acid, hydrofluoric acid, nitrous acid, formic acid, benzoic acid, hydrazoic acid, acetic acid, propionic acid, and carbonic acid.

[0064] When the acid is phosphoric acid, the concentration may be above 15%, and when the acid is acetic acid, the concentration may be above 5%.

[0065] After the above step (c), a step (d) of washing with alkali or water may be further included.

[0066] The alkali may be at least one selected from the group consisting of anhydrous sodium carbonate, sodium percarbonate, and sodium bicarbonate.

[0067] The above step (d) may be a step of neutralizing and removing the acid used in the above step (c), but if the acid in the above step (c) is acetic acid having a concentration greater than 5%, the neutralization process may be omitted and only washing with water may be used to sufficiently remove the by-products, which may be economically advantageous.

[0068] After the above step (d), the step (e) may be further included of performing reduced pressure concentration at a temperature of 90° C. to 120° C. for 1 to 5 hours to separate the thiomethylphenol derivative represented by Chemical Formula 1. The above reduced pressure concentration may be performed at a temperature of 90° C., 95° C., 100° C., 105° C., 110° C., 115° C., 120° C., or in a range between any two of these values, for 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, or in a range between any two of these values.

[0069] When the temperature during reduced pressure concentration satisfies the above range, the residual amount of thiol derivatives in the final product can be less than 0.1 wt %. In particular, when the temperature is above 110° C., the residual amount of thiol derivatives can be further reduced to less than 0.01 wt %.

[0070] The APHA value of the separated thiomethylphenol derivative after being placed at 120° C. for 72 hours may be less than 75, less than 70, less than 65, less than 60, less than 55 or less than 50.

[0071] Below, the embodiments of this specification will be described in more detail. However, the following experimental results are only representative experimental results in the above embodiments, and the scope and content of this specification cannot be narrowed or interpreted restrictively due to the embodiments, etc. Each effect in the various embodiments of this specification that is not clearly shown below will be specifically described in the corresponding part.

[0072] Example 1

[0073] 1.0 equivalent of water, 0.01 equivalent of phosphoric acid and 0.1 equivalent of acetic acid were added as solvents to a mixture of 100 parts by weight of o-cresol, 3 equivalents of paraformaldehyde, 2 equivalents of n-octylthiol and 0.3 equivalents of piperidine, and then the mixture was reacted at 100°C for 2 hours, and then the temperature was raised to 115°C and the reaction was carried out for 3 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 8.5% acetic acid, washed with water, and then concentrated under reduced pressure at 115°C for 3 hours to obtain 2,4-Bis(n-octylthiomethyl)-6-Methylphenol as a colorless liquid. The conversion rate of the 2,4-Bis(n-octylthiomethyl)-6-Methylphenol obtained above was 100%, and the purity was 98.0%. The residual n-octylthiol content was confirmed to be 0.005%.

[0074] Example 2

[0075] 1.0 equivalent of water, 0.01 equivalent of phosphoric acid and 0.1 equivalent of acetic acid were added as solvents to a mixture of 100 parts by weight of o-cresol, 2 equivalents of n-octyl mercaptan, 3 equivalents of paraformaldehyde and 0.3 equivalents of piperidine, and then the mixture was reacted at 100°C for 2 hours, and the temperature was raised to 115°C and the mixture was reacted for 3 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 8.5% acetic acid, washed with water, and then concentrated under reduced pressure at 100°C for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid. The conversion rate of the 2,4-bis(n-octylthiomethylene)-6-methylphenol obtained above was 100%, and the purity was 98.1%. The residual n-octyl mercaptan content was confirmed to be 0.02%.

[0076] Example 3

[0077] 1.0 equivalent of water, 0.01 equivalent of phosphoric acid and 0.1 equivalent of acetic acid were added as solvents to a mixture of 100 parts by weight of o-cresol, 3 equivalents of paraformaldehyde, 2 equivalents of n-octyl mercaptan and 0.3 equivalents of piperidine, and then the mixture was reacted at 100°C for 2 hours, and the temperature was raised to 115°C and the reaction was carried out for 3 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 17% phosphoric acid and 10% sodium carbonate aqueous solution, and then concentrated under reduced pressure at 100°C for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid. The conversion rate of the above-obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, and the purity was 97.8%. The residual n-octyl mercaptan content was confirmed to be 0.03%.

[0078] Example 4

[0079] 1.0 equivalent of water, 0.01 equivalent of phosphoric acid and 0.1 equivalent of acetic acid were added as solvents to a mixture of 100 parts by weight of o-cresol, 2 equivalents of n-octyl mercaptan, 3 equivalents of paraformaldehyde and 0.3 equivalents of piperidine, and then the mixture was reacted at 105°C for 2 hours, and the temperature was raised to 110°C and the reaction was carried out for 3 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 17% phosphoric acid and 10% sodium carbonate aqueous solution, and then concentrated under reduced pressure at 115°C for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid. The conversion rate of the above-obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, and the purity was 97.9%. The residual n-octyl mercaptan content was confirmed to be 0.006%.

[0080] Example 5

[0081] 2 equivalents of n-octyl mercaptan, 3 equivalents of paraformaldehyde, 1.0 equivalent of water, 0.01 equivalent of phosphoric acid, 0.1 equivalent of acetic acid, 0.3 equivalent of piperidine and 100 parts by weight of o-cresol were reacted at 95°C for 2 hours, and then at 105°C for 3 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 8.5% acetic acid, washed with water, and then concentrated under reduced pressure at 115°C for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid. The conversion rate of the above-obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, and the purity was 97.1%. The residual n-octyl mercaptan content was confirmed to be 0.005%.

[0082] Comparative Example 1

[0083] 1.0 equivalent of water and 0.15 equivalent of acetic acid as a solvent were added to a mixed solution of 100 parts by weight of o-cresol, 3 equivalents of paraformaldehyde, 2 equivalents of n-octyl mercaptan and 0.2 equivalents of dimethylamine, and then reacted at 120°C for 5 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 8.5% acetic acid, washed with water, and then concentrated under reduced pressure for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid. The conversion rate of the above-obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, and the purity was 97.0%.

[0084] Comparative Example 2

[0085] 1.0 equivalent of water, 0.01 equivalent of phosphoric acid and 0.1 equivalent of acetic acid were added as solvents to a mixture of 100 parts by weight of o-cresol, 3 equivalents of paraformaldehyde, 2 equivalents of n-octyl mercaptan and 0.3 equivalents of piperidine, and then the mixture was reacted at 100°C for 5 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with 17% phosphoric acid and 10% sodium carbonate aqueous solution, and then concentrated under reduced pressure for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid. The conversion rate of the 2,4-bis(n-octylthiomethylene)-6-methylphenol obtained above was 100%, and the purity was 96.3%.

[0086] Comparative Example 3

[0087] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 7% sulfuric acid and then post-treated with a 10% sodium carbonate aqueous solution. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100% and the purity was 97.5%.

[0088] Comparative Example 4

[0089] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 5% sulfuric acid and then post-treated with a 10% sodium carbonate aqueous solution. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100% and the purity was 97.4%.

[0090] Comparative Example 5

[0091] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 3% sulfuric acid and then post-treated with a 10% sodium carbonate aqueous solution. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100% and the purity was 97.9%.

[0092] Comparative Example 6

[0093] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 1% sulfuric acid and then post-treated with a 10% sodium carbonate aqueous solution. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, the purity was 97.5%, and by-products were present.

[0094] Comparative Example 7

[0095] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 10% acetic acid and then post-treated with water. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100% and the purity was 97.7%.

[0096] Comparative Example 8

[0097] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 8.5% acetic acid and then post-treated with 10% sodium carbonate. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100% and the purity was 97.7%.

[0098] Comparative Example 9

[0099] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 8.5% acetic acid and then post-treated with water. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100% and the purity was 97.5%.

[0100] Comparative Example 10

[0101] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 5% acetic acid and then post-treated with 10% sodium carbonate. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, the purity was 97.5%, and by-products were present.

[0102] Comparative Example 11

[0103] 2,4-bis(n-octylthiomethylene)-6-methylphenol was obtained as a colorless liquid in the same manner as in Comparative Example 2 except that the organic layer was treated with 5% acetic acid and then post-treated with water. The conversion rate of the obtained 2,4-bis(n-octylthiomethylene)-6-methylphenol was 100%, the purity was 97.6%, and by-products were present.

[0104] Comparative Example 12

[0105] 100 parts by weight of o-cresol, 3 equivalents of paraformaldehyde, 1.0 equivalent of water, 0.01 equivalent of phosphoric acid, 0.1 equivalent of acetic acid, 0.3 equivalent of piperidine and 2 equivalents of n-octyl mercaptan were reacted at 105° C. for 2 hours, and then at 95° C. for 3 hours to obtain a reaction product. The water layer was removed from the reaction product, and the organic layer was washed with acetic acid and water, and then concentrated under reduced pressure at 115° C. for 3 hours to obtain 2,4-bis(n-octylthiomethylene)-6-methylphenol as a colorless liquid, but the purity was 70.6%, by-products were present, and the content of unreacted n-octyl mercaptan was 7.16%.

[0106] Comparative Example 13

[0107] The process was carried out in the same manner as in Example 5 except that the primary reaction was carried out at 80°C and the secondary reaction was carried out at 90°C, but the reaction did not proceed sufficiently.

[0108] The by-product of Comparative Examples 6, 10, 11 and 12 is N-hydroxymethylpiperidine (NHP) represented by the following Chemical Formula 3, and the presence or absence of the by-product was confirmed by gas chromatography analysis.

[0109] [Chemical formula 3]

[0110]

[0111] With reference to the above-mentioned Examples to Comparative Examples, in Examples 1 to 5 in which the temperature is raised after the primary reaction to perform the secondary reaction, a high-purity thiomethylphenol derivative can be prepared. In particular, the above-mentioned Examples 1 to 5 can achieve a purity similar to that of Comparative Example 1 in which the reaction is performed at a relatively high temperature of 120° C., or can achieve a higher purity.

[0112] In addition, when the organic layer was washed with sulfuric acid having a pKa of -2 and then post-treated with sodium carbonate, if the sulfuric acid concentration was 3% or more, by-products could be removed, but there was a problem of possible reactor corrosion (Comparative Examples 3 to 6). As a result of gas chromatography analysis, when a 17% phosphoric acid aqueous solution having a pKa of more than 2.0 was used, by-products could be removed without the problem of reactor corrosion (Comparative Example 2). In addition, when the organic layer was washed with acetic acid having a concentration of more than 5%, a product of the same purity could be obtained by post-treatment with water alone without neutralization with sodium carbonate and without generating by-products (Comparative Examples 7 to 11).

[0113] In addition, it can be seen that the higher the temperature of the reduced pressure concentration performed after the acid treatment and post-treatment, the more significantly the content of residual n-octyl mercaptan is reduced (Examples 1 to 5).

[0114] Experimental example

[0115] 20 g of 2,4-bis(n-octylthiomethylene)-6-methylphenol prepared in the above examples and comparative examples was placed in a vial, placed in an oven, and the color change was measured at 120°C for 3 days. Whether the color changed was confirmed by measuring the color (APHA). If the APHA value of the sample is low, the color change is small, and if the APHA value is high, the color change is severe. The lower the thermal stability, the more severe the color change.

[0116] Table 1

[0117]

[0118]

[0119] Referring to Table 1, even when the same cleaning process was performed in Example 1, Comparative Example 1, Example 3, and Comparative Example 2, there were differences in the degree of discoloration, and thus it was confirmed that the thermal stability was relatively excellent.

[0120] Although the reason for this difference is unclear, it may be due to the improvement of product purity through two-stage reactions with different reaction temperatures and differences in impurity composition.

[0121] Referring to the above example, 2 The product prepared by reacting at T for 5 hours was compared with the product prepared by 1 The reaction was carried out for 2 hours at T 2 The product prepared by reacting at a temperature of 3 hours can be superior in purity and thermal stability, and can also minimize energy consumption.

[0122] The above description of this specification is only illustrative, and any person skilled in the art of one aspect of this specification will understand that it can be easily transformed into other specific forms without changing the technical ideas or essential features recorded in this specification. Therefore, the above-mentioned embodiments are only illustrative in various aspects, but are not limited to this. For example, each structural component described as a single type can also be implemented in a dispersed manner, and similarly, the structural components described using dispersed methods can also be implemented in a combined form.

[0123] The scope of the present specification is indicated by the appended claims, and all changes or modifications derived from the meaning, scope and equivalent concepts of the claims should be interpreted as being included in the scope of the present specification.

Claims

1. A method for preparing a thiomethylphenol derivative, comprising: Step (a), in the presence of a heterocyclic base having 3 to 10 carbon atoms and an acid, reacting a phenol derivative represented by the following chemical formula 2, a thiol derivative represented by R4SH and paraformaldehyde at a reaction temperature T1; Step (b), performing a secondary reaction at a reaction temperature T2, thereby preparing a thiomethylphenol derivative represented by the following chemical formula 1; Step (c), washing the organic layer in the product of step (b) with an acid to purify the organic layer in the product of step (b), wherein the acid is phosphoric acid having a concentration of 15% or more or acetic acid having a concentration of greater than 5%; Step (d), washing with alkali or water, wherein the alkali is at least one selected from the group consisting of anhydrous sodium carbonate, sodium percarbonate and sodium bicarbonate; and Step (e), performing reduced pressure concentration at a temperature of 100° C. to 120° C. for 1 to 5 hours to separate the thiomethylphenol derivative represented by Chemical Formula 1, The preparation method of the above-mentioned thiomethylphenol derivative meets the requirements of 95°C <T1+5℃≤T2<120℃: [Chemical formula 1] [Chemical formula 2] In the formula, R1 and R2 are each independently selected from hydrogen, deuterium, C1-C 16 Straight or branched alkyl, C5~C 16 Cycloalkyl or aralkyl-containing -CH2SR3, R3 and R4 are each selected from C1 to C 16 Straight or branched alkyl, C5~C 16 In the cycloalkyl or aralkyl group, R 11 and R 22 Each independently selected from hydrogen, deuterium, C1-C 16 Straight or branched alkyl, C5~C 16 In the cycloalkyl or aralkyl group, n is 0 or 1.

2. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: The above steps (a) and (b) are performed for 1 to 5 hours respectively.

3. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: The step (a) is carried out in the presence of 0.5 to 50.0 equivalents of a solvent relative to 1 equivalent of the phenol derivative.

4. The method for preparing a thiomethylphenol derivative according to claim 3, wherein: The above solvent is water or alcohol.

5. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: In the above step (a), 0.01 to 0.50 equivalents of the base are used relative to 1 equivalent of the above phenol derivative.

6. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: The base in step (a) is at least one selected from the group consisting of pyrrole, pyrrolidine, imidazole, pyridine, piperidine, piperazine and pyrazine.

7. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: In the above step (a), 0.01 to 0.90 equivalents of the acid are used relative to 1 equivalent of the above phenol derivative.

8. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: The acid in step (a) is at least one selected from the group consisting of chlorous acid, phosphoric acid, arsenic acid, chloroacetic acid, hydrofluoric acid, nitrous acid, formic acid, benzoic acid, hydrazoic acid, acetic acid, propionic acid and carbonic acid.

9. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: In the above step (a), 2.0 to 6.0 equivalents of the thiol derivative are used relative to 1 equivalent of the above phenol derivative.

10. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: In the above step (a), 2.0 to 6.0 equivalents of paraformaldehyde are used relative to 1 equivalent of the above phenol derivative.

11. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: The pKa of the acid in the above step (c) is 2.0 or more.

12. The method for preparing a thiomethylphenol derivative according to claim 1, wherein: The APHA value of the separated thiomethylphenol derivative is less than 75 after being placed at 120° C. for 72 hours.

Images