Phenolic anti-aging agent as well as synthesis method and application thereof

Abstract

The invention discloses a phenolic anti-aging agent as well as a synthesis method and application thereof, thiodialkyl alcohol is taken as a raw material, and under the catalysis of p-toluenesulfonic acid, the thiodialkyl alcohol and 3-(3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid are subjected to esterification reaction to obtain the phenolic sulfur-containing anti-aging agent. The phenol sulfur-containing anti-aging agent synthesized by the invention has a good anti-aging effect, and can be used for improving the mechanical properties of solid propellants, inhibiting embrittlement and increasing the tensile strength and ductility.

Description

Technical Field

[0001] The invention belongs to the field of functional materials and relates to a phenol antioxidant and a synthesis method and application thereof. Background Art

[0002] Antioxidant is one of the indispensable main functional additives in solid propellant products. Its use can effectively extend the storage time of propellant and can extend the service life of propellant to a large extent.

[0003] In solid propellants, α-aromatic amines or b-aromatic urea derivatives are usually added to inhibit propellant aging. These substances have been proven to be highly carcinogenic and are extremely detrimental to the health of production and users. Phenolic antioxidants are also a commonly used high-quality antioxidant. Their molecules contain reactive OH functional groups, which can compete with polymers for peroxide free radicals·; through the transfer of hydrogen atoms, relatively stable free radicals ArO· are formed, thereby inhibiting the growth of free radical chains and playing an anti-aging role. Phenolic antioxidants are applied to solid propellants, which can not only inhibit their aging, but also improve the tensile strength of the propellants. However, their elongation decreases and the comprehensive mechanical properties are not good. It is urgent to develop new antioxidants to solve the propellant aging problem while increasing the tensile strength and elongation. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a phenolic antioxidant and a synthesis method and application thereof, so as to solve the aging problem of propellants while increasing the tensile strength and elongation. The present invention combines a phenolic structure with a sulfurized structure to produce a synergistic effect during the application process, thereby suppressing the embrittlement of solid propellants while improving their tensile strength and elongation.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve the above problems:

[0006] A phenolic antioxidant, the structural formula of which is shown in (I):

[0007]

[0008] Wherein R is an alkyl group, including methyl, ethyl, propyl, butyl, and pentyl.

[0009] The synthesis method of the phenolic antioxidant comprises the following steps:

[0010] Thiodialkyl alcohol and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid are added to toluene, and refluxed and dehydrated at a temperature of 110-115°C under the catalysis of p-toluenesulfonic acid. After the reaction is completed, it is naturally cooled to room temperature, washed with water until neutral, and toluene is removed by vacuum distillation to obtain a phenolic sulfur-containing antioxidant.

[0011] The present invention also includes the following technical features:

[0012] Specifically, the molar ratio of the thiodialkyl alcohol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and p-toluenesulfonic acid is 1:2-3:0.04-0.06, and the feed ratio of the thiodialkyl alcohol to toluene is 1 mol:600 ml.

[0013] Specifically, the thiodialkyl alcohol includes thiodimethyl alcohol, and the obtained phenolic sulfur-containing antioxidant includes thiobis(1,2-dimethyl)-di[3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate.

[0014] Specifically, the molar ratio of thiodimethyl alcohol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and p-toluenesulfonic acid is 1:2.2:0.044, and the feed ratio of 2-ethyl-2-nitro-1,3-propanediol to toluene is 1 mol:600 ml.

[0015] The phenolic antioxidant synthesized by the synthesis method is used as an antioxidant in solid propellants.

[0016] Compared with the prior art, the present invention has the following technical effects:

[0017] (1) The phenolic sulfur-containing antioxidant of the present invention has both phenolic and sulfurized structures, and can produce synergistic effects when used in propellants. (2) The preparation process of the phenolic sulfur-containing antioxidant of the present invention is simple, safe and reliable. (3) The phenolic sulfur-containing antioxidant of the present invention can effectively improve the mechanical properties of solid propellants. Compared with the phenolic antioxidant 2,2'-thiobis(4-methyl-6-tert-butylphenol), the embrittlement parameter is reduced from 33.58 to 26.72; under low temperature conditions (-40°C), the tensile strength is increased from 23.3MPa to 28.5MPa, and the elongation is increased from 1.75% to 3.42%; under high temperature conditions (50°C), the tensile strength is increased from 1.22MPa to 1.31MPa, and the elongation is increased from 15.5% to 29.8%. DETAILED DESCRIPTION

[0018] The present invention provides a phenolic antioxidant and a synthesis method and application thereof, wherein the synthesis route is:

[0019]

[0020] Using thiodialkyl alcohol as raw material, esterification reaction with 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid occurs under the catalysis of p-toluenesulfonic acid to obtain a phenolic sulfur-containing antioxidant.

[0021] The phenolic sulfur-containing antioxidant of the present invention has a structure as shown in (I):

[0022]

[0023] Wherein R is an alkyl group such as methyl, ethyl, propyl, butyl, pentyl, etc.

[0024] The synthesis method of the phenolic sulfur-containing antioxidant of the present invention comprises the following steps:

[0025] Taking thiodialkyl alcohol as raw material, thiodialkyl alcohol and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid are added to toluene, and reflux dehydration is carried out at a temperature of 110-115°C under the catalysis of p-toluenesulfonic acid. After the reaction is completed, it is naturally cooled to room temperature, washed with water until neutral, and toluene is removed by reduced pressure distillation to obtain a phenolic sulfur-containing antioxidant.

[0026] The molar ratio of thiodialkyl alcohol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and p-toluenesulfonic acid is 1:2-3:0.04-0.06, and the feed ratio of thiodialkyl alcohol to toluene is 1 mol:600 ml.

[0027] The preferred method for synthesizing a phenolic sulfur-containing antioxidant uses thiodimethyl alcohol as a raw material and comprises the following steps:

[0028] Thiodimethyl alcohol and 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid are added to toluene, and refluxed and dehydrated at 110-115°C under the catalysis of p-toluenesulfonic acid. After the reaction is completed, the mixture is naturally cooled to room temperature, washed with water until neutral, and toluene is removed by vacuum distillation to obtain thiobis(1,2-dimethyl)-di[3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate. The molar ratio of thiodimethyl alcohol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and p-toluenesulfonic acid is 1:2.2:0.044, and the feed ratio of 2-ethyl-2-nitro-1,3-propanediol to toluene is 1 mol:600 ml.

[0029] The synthesized phenol antioxidant of the invention is used as an antioxidant in solid propellant.

[0030] Specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0031] Embodiment 1:

[0032] The present embodiment provides a phenolic antioxidant and a synthesis method thereof, comprising the following steps: Preparation of thiobis(1,2-dimethyl)-di[3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate: Under stirring, at a temperature of 20°C to 25°C, 0.5 mol of thiodimethyl alcohol, 1.1 mol of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.022 mol of p-toluenesulfonic acid, and 300 ml of toluene are sequentially added into a reaction bottle, and the mixture is refluxed and dehydrated at 110 to 115°C until the solvent in the water separator becomes transparent, cooled naturally to room temperature, washed with water for multiple times until neutral, and toluene is removed by reduced pressure distillation to obtain 267.7 g of a light brown viscous liquid with a yield of 87.07%.

[0033] Structure identification:

[0034] Infrared spectrum: IR (KBr, cm -1 ),υ:3481(-OH), 3030(CH), 1752(C=O), 1591(C=C), 1166, 1017(COC), 620(CS);

[0035] NMR spectrum: 1 H NMR(DMSO,500MHz),δ:6.89(s,2H,2CH),6.72(s,2H,2OH),5.23(s,8H,4CH 2 ),2.85(m,4H,2CH 2 ),2.53(m,4H,2CH 2 ),1.37(s,36H,9CH 3 ). 13 C NMR (DMSO, 125MHz), δ: 173.1 (C=O), 151.8 (CH), 137.5 (CH), 131.2 (CH), 123.9 (CH), 54.1 (CH 2 ),34.7(C),33.4(CH 2 ),31.6(CH 3 ),31.1(CH 2 ).

[0036] Elemental analysis: Molecular formula C 36 H 54 O 6 S

[0037] Theoretical value (%): C 70.32, H 8.85;

[0038] Found (%): C 70.29, H 8.79.

[0039] The above structural identification data confirmed that the obtained substance was indeed thiobis(1,2-dimethyl)-di[3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate.

[0040] Embodiment 2:

[0041] The present embodiment provides a phenolic antioxidant and a synthesis method thereof, comprising the following steps: under stirring, 0.5 mol of thiodimethyl alcohol, 1 mol of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.02 mol of p-toluenesulfonic acid, and 300 ml of toluene are sequentially added into a reaction bottle at a temperature of 20° C. to 25° C., refluxed and dehydrated at 110 to 115° C. until the solvent in the water separator is transparent, cooled naturally to room temperature, washed with water for multiple times until neutral, and toluene was removed by reduced pressure distillation to obtain 250.2 g of a light brown viscous liquid with a yield of 81.38%.

[0042] Embodiment 3:

[0043] The present embodiment provides a phenolic antioxidant and a synthesis method thereof, comprising the following steps: under stirring, 0.5 mol of thiodimethyl alcohol, 1.3 mol of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.026 mol of p-toluenesulfonic acid, and 300 ml of toluene are sequentially added into a reaction bottle at a temperature of 20° C. to 25° C., refluxed and dehydrated at 110 to 115° C. until the solvent in the water separator is transparent, cooled naturally to room temperature, washed with water for multiple times until neutral, and toluene was removed by reduced pressure distillation to obtain 264.2 g of a light brown viscous liquid with a yield of 85.94%.

[0044] Embodiment 4:

[0045] The present embodiment provides a phenolic antioxidant and a synthesis method thereof, comprising the following steps: under stirring, at a temperature of 20° C. to 25° C., 0.5 mol of thiodimethyl alcohol, 1.5 mol of 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid, 0.03 mol of p-toluenesulfonic acid, and 300 ml of toluene are sequentially added into a reaction bottle, refluxed and dehydrated at 110 to 115° C. until the solvent in the water separator is transparent, cooled naturally to room temperature, washed with water for multiple times until neutral, and toluene is removed by reduced pressure distillation to obtain 264.9 g of a light brown viscous liquid with a yield of 86.16%.

[0046] Application of the phenolic sulfur-containing antioxidant of the present invention:

[0047] The phenolic sulfur-containing antioxidant of the invention has good anti-aging effect and can be used to improve the mechanical properties of solid propellants, inhibit embrittlement, and increase tensile strength and elongation.

[0048] Table 1 Tensile strength and embrittlement parameters of solid propellants

[0049]

[0050] Compared with the traditional phenolic antioxidant 2,2'-thiobis(4-methyl-6-tert-butylphenol), the embrittlement parameter decreased by 20.4%, the low-temperature tensile strength increased by 22.3%, and the elongation increased by 95.4%; the high-temperature tensile strength increased by 7.4%, and the elongation increased by 92.3%, indicating that phenolic sulfur-containing antioxidants have a good application effect in solid propellants and can effectively improve their mechanical properties.

Claims

1. A phenolic antioxidant, characterized in that: Its structural formula is shown in (I): Wherein R is an alkyl group, including methyl, ethyl, propyl, butyl, and pentyl.

2. The method for synthesizing the phenolic antioxidant according to claim 1, characterized in that: The steps include: Thiodialkyl alcohol and 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid are added to toluene, and refluxed and dehydrated at a temperature of 110-115°C under the catalysis of p-toluenesulfonic acid. After the reaction is completed, it is naturally cooled to room temperature, washed with water until neutral, and toluene is removed by vacuum distillation to obtain a phenolic sulfur-containing antioxidant.

3. The synthetic method of phenolic antioxidant as claimed in claim 2, characterized in that, The molar ratio of the thiodialkyl alcohol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid and p-toluenesulfonic acid is 1:2-3:0.04-0.06, and the feed ratio of the thiodialkyl alcohol to toluene is 1 mol:600 ml.

4. The synthetic method of phenolic antioxidant as claimed in claim 2, characterized in that, The thiodialkyl alcohol includes thiodimethyl alcohol, and the obtained phenolic sulfur-containing antioxidant includes thiobis(1,2-dimethyl)-di[3-(3,5-di-tert-butyl-4-hydroxyphenyl)]propionate.

5. The synthetic method of phenolic antioxidant as claimed in claim 4, characterized in that, The molar ratio of thiodimethyl alcohol, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid and p-toluenesulfonic acid is 1:2.2:0.044, and the feed ratio of 2-ethyl-2-nitro-1,3-propanediol to toluene is 1 mol:600 ml.

6. Use of the phenolic antioxidant synthesized by the synthesis method of the phenolic antioxidant according to claim 2 as an antioxidant in solid propellants.

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