KR101367955B1 - manufacturing method of 2-tert-butyl hydroquinone as antioxidant compounds for biodiesel - Google Patents

Abstract

The present invention relates to a preparation method of 2-tert-butyl hydroquinone and butyl hydroxyanisole used as a hydroquinone antioxidant compound for biodiesel. The preparation method according to the present invention is unreacted by controlling the reaction temperature and time. It is a high purity, simple, economical and efficient method of butyl hydroquinone and butyl hydroxyanisole by reusing the hydroquinone and solvent.

Description

A method for producing 2-tertiary-butyl hydroquinone as an antioxidant compound for biodiesel. {manufacturing method of 2-tert-butyl hydroquinone as antioxidant compounds for biodiesel}

The present invention relates to a method for preparing 2-tert-butyl hydroquinone and 2-tert-butyl hydroxyanisole that can be used as a hydroquinone antioxidant compound for biodiesel.

Bio-fuels, which have recently been attracting attention as a clean alternative energy source, are environmentally friendly fuels that substitute existing fossil fuels due to excessive dependence on fossil fuels, such as coal and oil, and environmental pollutants. .

Biodiesel is made from renewable bio-resources such as vegetable oils such as rapeseed oil, soybean oil, coconut oil, palm oil, sunflower oil, rice bran oil, palm oil and animal preservation such as waste cooking oil and waste oil. Biodiesel can replace diesel in its own right and is used for existing light oil passenger cars and van without any engine modifications.

 In general, the natural stability of biodiesel varies greatly depending on the content of natural unsaturated fatty acids. Biodiesel is easily degraded by autoxidation of unsaturated fatty acids and is an additive for maintaining the cleanliness of the engine Additives such as a clean dispersant, an antioxidant, a corrosion inhibitor, and a low-temperature fluidity improving agent.

As antioxidants developed so far, natural antioxidants include tocopherol, ascorbic acid, and beta-carotene. Synthetic antioxidants are mainly hydroxy-substituted hydroxy groups, Butylated hydroxyanisole, butylated hydroxytoluene, Tertiary butyl hydroquinone, and propyl gallate.

Hydroxyanisole substituted with dibutyl hydroquinone and butyl group has been reported by L. Zhou et al. As a byproduct such as dibutyl hydroquinone, which is a byproduct, and the yield is low, 9 (2008) 2274-2277).

However, there is still a need for improvement of environment-friendly methods due to the contradiction of using environmentally-produced antioxidants in biodiesel introduced to reduce the environmental burden due to the low yield and the large environmental burden.

L. Zhou. et al. Catalysis Communications 9 (2008) 2274-2277

The present invention provides a method for preparing 2-t-butyl hydroquinone, which is an antioxidant for improving oxidation stability of biodiesel.

In addition, the present invention provides a method for producing 2-tert- butyl hydroquinone with high purity and yield while being able to be re-collected with less environmental burden.

The present invention also provides a method for preparing tert-butyl hydroxyanisole using 2-tert-butyl hydroquinone prepared according to the present invention.

The present invention provides a method for preparing 2-tert-butyl hydroquinone useful as an antioxidant for improving the oxidation stability of biodiesel.

Method for producing 2-tert-butyl hydroquinone according to the present invention

a) adding and stirring hydroquinone and phosphoric acid to an organic solvent;

b) adding 2-tert-butanol or isobutene to the reaction mixture in the above step to react;

c) separating and recovering the unreacted hydroquinone by filtering the solid of the reaction mixture in the above step;

d) separating the phosphoric acid from the reaction mixture of the step;

e) separating and purifying 2-ter-butyl hydroquinone as a product and the remaining hydroquinone from the reaction mixture in which the phosphoric acid of the step is separated.

In addition, the present invention further comprises the step of a) further comprising the step of reusing the at least one recovery selected from the phosphoric acid recovered in step d), the hydroquinone recovered in step c) and the hydroquinone recovered in step e) before step a) In step e) is characterized in that it is performed sequentially.

Separation of phosphoric acid in step d) is possible by layer separation with the organic solvent used in step a).

Separation of unreacted hydroquinone and the target 2-ter-butyl hydroquinone reduces the by-products by efficiently controlling the reaction conditions in step b) to increase the yield of 2-tert-butyl hydroquinone and to remove unreacted hydroquinone. Recovery rate can be adjusted.

 Specifically, in order to reduce the production of by-products such as 2,5-dibutyl hydroquinone as a by-product in step b) as much as possible and to increase the yield of the target 2-tert-butyl hydroquinone, the reaction temperature is 70 ~. It is preferable to perform for 1 to 4 hours at 110 ℃, more preferably for 1 to 2 hours at 70 ~ 90 ℃.

That is, the present invention controls the reaction time and temperature to increase the yield of the target 2-tert- butyl hydroquinone while reducing the production of by-products characterized in that the remaining hydroquinone and phosphoric acid to recover and reuse without reaction do.

 2-tert-butyl hydroquinone is produced by reusing phosphoric acid known as strong acid such as sulfuric acid as many times as possible to reduce the concentration of phosphoric acid, thereby reducing the environmental burden, and reusing the hydroquinone used as starting material. It can have the effect of reducing the manufacturing cost of.

Separation and purification of hydroquinone and 2-tert-butyl hydroquinone for reuse of the hydroquinone, that is, the separation tablet of step e) may be purified using an alkaline aqueous solution or purified with an organic solvent.

First, the purification method using alkaline aqueous solution,

e1-1) adding an alkaline aqueous solution to the reaction mixture of the step and stirring;

e1-2) cooling the reaction mixture to room temperature and filtering the resulting solid to separate unreacted hydroquinone; and

e1-3) may further include the step of neutralizing the filtrate of the step to separate the product 2-tert-butyl hydroquinone as a solid.

When the reaction mixture of step d) is added with an alkaline aqueous solution and stirred, and the reaction mixture is cooled to room temperature, unreacted hydroquinone is precipitated as a solid. In the filtrate, 2-tert-butyl hydroquinone and by-products are present in the filtrate. Done.

The filtrate may be neutralized to obtain 2-tert-butyl hydroquinone as a product by recrystallization, but the present invention is not limited thereto.

The alkaline aqueous solution may be any one selected from aqueous sodium hydroxide solution, sodium carbonate, sodium bicarbonate and potassium hydroxide, and sodium carbonate and potassium hydroxide are preferable in terms of being able to dissolve hydroquinone better.

It is preferable that the concentration of the alkaline aqueous solution is 0.1 mole to 1.0 mole. The aqueous alkali solution of this concentration sufficiently dissolves the starting material hydroquinone to facilitate separation from the product 2-tert-butyl hydroquinone to increase the purity. Useful in terms of

Stirring performed by adding the alkaline aqueous solution as described above may be performed for 0.5 to 4 hours at 40 ~ 80 ℃ and stirred for 1 to 2 hours at 70 ~ 80 ℃ by starting the unreacted starting material in the reaction mixture Phosphorus hydroquinone is sufficiently dissolved to effectively separate it.

The neutralization can be done by conventional methods, and for example concentrated hydrochloric acid can be used.

In addition, the method of purifying with an organic solvent which is one of the separation and purification methods of step e) of the present invention,

 e2-1) drying the reaction mixture of the above step under reduced pressure;

e2-2) adding a solvent to the solid obtained by vacuum drying, cooling to 10-24 ° C., and filtering to obtain hydroquinone as a filtrate;

e2-3) recrystallizing the obtained solid with an organic solvent to obtain 2-tert-butyl hydroquinone.

In addition, the separation and purification method of step e) of the present invention recrystallizes the filtrate of step e2-2) or step e2-3) with an organic solvent for recovery of unreacted hydroquinone and high purity of 2-tert-butyl hydroquinone. Then, the process of separating and purifying hydroquinone and t-butyl hydroquinone may be repeated.

The organic solvent may be used as long as it is an organic solvent used in a conventional reaction, a mixture of two or more may be more preferable, and an organic solvent used for phosphoric acid and hydroquinone in step a).

For example, it may be any one or a mixture of two or more selected from xylene, dioxane, methyl isobutyl ketone and toluene, and preferably xylene, methyl isobutyl ketone, toluene in consideration of dissolution of the starting material hydroquinone. .

The present invention also provides a method for preparing tert-butyl hydroxyanisole prepared by reacting dimethyl sulphate with 2-tert-butyl hydroquinone prepared according to the present invention.

tert-Butyl hydroxyanisole can be obtained by adding dimethyl sulphate to 2-tert-butyl hydroquinone prepared according to the present invention in an organic solvent, stirring for a predetermined time, and then adding a base such as sodium hydroxide to react. have.

2-tert-butyl hydroquinone and tert-butyl hydroxyanisole prepared according to the present invention can be used as an antioxidant. Hydrogen is applied to 2-tert-butyl hydroquinone and tert-butyl hydroxyanisole. It becomes a phenoxy radical, and since the phenoxy radical is stabilized by resonance, its activity against antioxidant is very high, and thus it can be particularly useful as an antioxidant of biodiesel.

The method for preparing 2-tert-butyl hydroquinone according to the present invention is recyclable to the reactants and is environmentally friendly and economical.

In addition, the method for preparing 2-tert-butyl hydroquinone according to the present invention is to separate and purify the unreacted hydroquinone and the target 2-tert-butyl hydroquinone by a simple method, unreacted hydroquinone and 2-tert-butyl hydro. Quinones can be obtained with high purity.

In addition, the present invention can obtain tert-butyl hydroxyanisole using 2-tert-butyl hydroquinone prepared economically and efficiently according to the present invention.

In addition, 2-tert-butyl hydroquinone and tert-butyl hydroxyanisole prepared according to the present invention can be effectively used as an antioxidant of biodiesel.

The present invention as described above is described in more detail through the following examples, the present invention is not limited by the following examples.

Example 1 Preparation of 2-tert-Butylhydroquinone Using Hydroquinone and Butanol

66 g (0.6 mol) of Hydroquinone was added to a mixture of 240 ml of 85% Phosphoric acid and 240 ml of P-Xylene, and the reaction solution was heated and stirred to 110 ° C. 60 ml of t-butanol (t-BuOH) was added dropwise to the reaction solution over 1 hour. The mixture was stirred at room temperature for 1 hour and then cooled to room temperature, and the precipitated solid hydroquinone was separated by filtration. The phosphoric acid layer of the filtrate after filtration is separated and reused. The separated P-xylene layer is cooled to room temperature and the precipitated solid is filtered. The filtered solid is partially dissolved using an aqueous solution of sodium hydroxide (10.3 g of caustic soda / 100 ml of water). The reaction solution was filtered to remove insoluble components, and 36 g of solid di-t-butyl hydroquinone (Crude yield: 35%, purity: 94%) was obtained. The filtrate obtained by filtration was neutralized with concentrated hydrochloric acid, and the precipitated solid was filtered and dried to obtain 50 g of a solid (Crude yield 50%, purity 92%). The obtained solid was recrystallized with P-xylene to obtain 40 g of solid 2-tert-butylhydroquinone (yield: 40%, purity: 99%).

Molecular weight: Theoretical value M = 166, Experimental value M = 166

Elemental analysis: Theoretical values C ₁₀ H ₁₄ O ₂ , C 72.26, H 8.49, C 71.83, H 8.43,

¹ H NMR (300 MHz, CDCl ₃ ) 1.36 (d, 9H, J = 3.30 Hz), 6.52 (d, 2H, J = 1.65 Hz), 6.75 (t, 1H, J = 1.80 Hz), 10.10 (s, 1H), 11.20 (s, 1H)

Example 2 Preparation of t-Butylhydroquinone Using Hydroquinone and Isobutene

16.5 g (0.15 mol) of hydroquinone is added to the reaction solution with 16.5 g of 70% Phosphoric acid, 60 g of methyl iso butyl ketone, and xylene mixture into the reaction solution. Stirred with heating. 5.9 g (0.1 mole) of isobutene gas was injected into the reaction solution over 3 hours. After injecting, the mixture was further heated and stirred for 1 hour at a temperature of 90 ° C. The reaction solution was cooled to room temperature, and the precipitated crystals were filtered to recover hydroquinone (recovery rate; 8.3 g (50%)). The phosphate layer was separated from the filtrate obtained by filtration and reused in the next reaction solution. The methyl iso butyl ketone and the xylene layer were dried under reduced pressure. Methyl iso butyl ketone and 25 g of a mixture of xylene were added to the solid obtained by drying under reduced pressure, and the mixture was heated and stirred, followed by cooling to separate the precipitated solid hydroquinone. The filtrate obtained by filtration was distilled under reduced pressure to precipitate crystals. The solid thus obtained was filtered and dried while washing with P-xylene to obtain 10.34 g of 2-tert-butyl hydroquinone (yield 41.5%, purity 96%). .

Example 3 Preparation of t-butylhydroquinone by reusing the first recovered phosphoric acid and hydroquinone

The previously recovered hydroquinone and 16.5 g of reagent grade Hydroquinone (0.15 mol) and 16.5 g of 70% Phosphoric acid previously obtained from the reactant are reused and added to the reaction solution. 60 g of methyl iso butyl ketone and xylene mixture were added to the reaction solution, and the reaction solution was heated and stirred at 70 ° C. 5.9 g (0.1 mole) of isobutene gas was introduced into the reaction solution over 3 hours. After injecting, the mixture was heated and stirred for 1 hour at a temperature of 90 ° C. The reaction solution was cooled to room temperature, and hydroquinone, a precipitated crystal, was separated by filtration (recovery rate; 5.0 g (30%). The phosphoric acid layer of the filtrate obtained by filtration was separated, reused in the next reaction solution, and methyl isobutyl ketone. (Methyl iso butyl ketone) and xylene layer are dried under reduced pressure, 25 g of methyl iso butyl ketone and xylene mixture are added to the solid obtained by drying under reduced pressure, and the mixture is heated and stirred. The filtered filtrate was distilled under reduced pressure to precipitate crystals, which were then filtered and dried while washing the solid with P-xylene to yield 12.7 g of 2-tert-butyl hydroquinone (yield 51.0%, purity). 94%).

Example 4 Preparation of t-butylhydroquinone by reusing the second recovered phosphoric acid and hydroquinone

Phosphoric acid and hydroquinone obtained by secondary recovery were reused to obtain 15.88 g (yield 60%, purity 94%) of tert-butylhydroquinone in the same manner as in Example 3.

Example 5 Preparation of 2-tert-butylhydroquinone using hydroquinone and isobutene

27.52 g (0.25 mol) of hydroquinone was added 27.52 g of 70% Phosphoric acid and 100 g of methyl iso butyl ketone and xylene were added to the reaction solution. Stirring with heating. 9.8 g (0.175 mole) of isobutene gas was introduced into the reaction solution over 3 hours. After injecting, the mixture was heated and stirred for 1 hour at a temperature of 90 ° C. The reaction solution was cooled to room temperature and the precipitated solid hydroquinone was separated by filtration (recovery rate; 10.78 g (39%). The phosphate layer was separated from the filtrate obtained by filtration and reused in the next reaction solution, and methyl isobutyl ketone ( Methyl iso butyl ketone) and xylene layer were dried under reduced pressure, 27.6 g of the solid obtained by drying under reduced pressure was heated to 80 DEG C using an aqueous sodium hydroxide solution (a mixture of 7.0 g of caustic soda and 100 ml of water). The resulting filtrate was neutralized with concentrated hydrochloric acid, and then the precipitated solid was filtered and dried to give 27.6 g of solid (Crude yield 66.5%, purity 72%). Recrystallization from xylene afforded 18.4 g of solid 2-tert-butyl hydroquinone (yield 43%, purity 97%).

Example 6 Preparation of 2-tert-butylhydroquinone using hydroquinone and isobutene

Hydroquinone (Physphoric acid), methyl iso butyl ketone and a mixture of xylene (Xylene) is added to the reaction solution and the reaction solution is heated and stirred to 70 ℃. Isobutylene gas is injected into the reaction solution over 3 hours. After injecting, the mixture was heated and stirred for 1 hour at a temperature of 90 ° C. The reaction solution was cooled to room temperature, and hydroquinone, a precipitated crystal, was separated by filtration. The phosphate layer was separated from the filtrate obtained by filtration and reused in the next reaction solution, and the methyl iso butyl ketone and the xylene layer were dried under reduced pressure. The solid obtained by drying under reduced pressure was heated to 80 ° C. using distilled water, cooled, and filtered to separate hydroquinone as a precipitated solid. The solid obtained by filtration was heated using a mixture of xylene and dioxane, and then cooled, and then the precipitated solid was filtered and the remaining filtrate was dried under reduced pressure to give 21.6 g of 2-tert-butyl hydroquinone (yield%). Got it.

Example 7 tert-Butylhydroanisole Synthesis

50 g (0.3 mol) of 2-tert-butylhydroquinone is added to a mixed solution of 160 ml of n-hexane and 30 ml of distilled water and stirred for 20 minutes. To the mixture was added 45.4 g (0.36 mol) of dimethyl sulfate (Dimethyl sulfate). After the addition, the mixture is stirred for 20 minutes, and then 16.8 g of sodium hydroxide is dissolved in 20 ml of H ₂ O, and the solution is slowly added dropwise to the above mixed solution over 1 hour. When added dropwise, the temperature should not exceed 50 ℃. The mixture is stirred at room temperature for 1 hour. The reaction solution is neutralized with an aqueous solution of 50% sulfuric acid (H ₂ SO ₄ ), then the n-hexane layer is extracted, and water is removed by adding anhydrous magnesium sulfate. The precipitated solid was filtered (Crude yield: 96%, purity: 89%) and recrystallized using n-hexane. The precipitated solid was filtered and dried to obtain 45 g of solid tert-butyl (Yield: 84%, purity: 99%).

Molecular weight: theoretical value M = 180, experimental value M = 180; Elemental Analysis: Theoretical C ₁₁ H ₁₆ O ₂ , C 73.30, H 8.95, Experimental C 73.39, H 8.89, ¹ H NMR (300 MHz, CDCl ₃ ) 1.41 (d, 9H, J = 9.30 Hz), 3.72 (s, 3H), 6.60 (d, 2H, J = 1.50 Hz), 6.86 (t, H, J = 2.80 Hz), 10.32 (s, H)

Claims (10)

a) adding and stirring hydroquinone and phosphoric acid to the organic solvent;
b) reacting by adding tert-butanol or isobutene to the reaction mixture of the above step;
c) filtering the solid of the reaction mixture of the step to separate the unreacted hydroquinone;
d) separating phosphoric acid from the filtrate;
e) separating and purifying the product tert-butyl hydroquinone and unreacted hydroquinone from the reaction mixture in which the phosphoric acid of the step is separated; but including the phosphoric acid recovered in step d) before step a), in step c) A method for preparing tert-butyl hydroquinone which is carried out sequentially from step a) to step e) further comprising the step of reusing the recovered hydroquinone and the recovered hydroquinone in step e). delete The method of claim 1,
Separation and purification of the step e),
e1-1) adding an alkaline aqueous solution to the reaction mixture of the step and stirring;
e1-2) cooling the reaction mixture to room temperature and filtering the resulting solid to separate unreacted hydroquinone; and
e1-3) A method for producing 2-tert-butyl hydroquinone, further comprising the step of neutralizing the filtrate of the step to separate 2-tert-butyl hydroquinone as a solid. The method of claim 3, wherein
The alkaline aqueous solution is a method for producing 2-tert-butyl hydroquinone which is any one selected from aqueous sodium hydroxide solution, sodium carbonate, sodium bicarbonate and potassium hydroxide. The method of claim 3, wherein
The alkaline aqueous solution is a method of producing 2-tert-butyl hydroquinone having a concentration of 0.1 ~ 1.0 mol. The method of claim 3, wherein
Heat stirring of the step e1-1) is carried out for 1 to 2 hours at 70 ~ 80 ℃ method of producing 2-tert- butyl hydroquinone. The method of claim 1,
Separation and purification of the step e),
e2-1) drying the reaction mixture of the above step under reduced pressure;
e2-2) adding a solvent to the solid obtained by vacuum drying, cooling to 10-24 ° C., and filtering to obtain hydroquinone;
e2-3) A method for producing 2-tert-butyl hydroquinone further comprising the step of recrystallization of the obtained filtrate with an organic solvent to obtain 2-tert-butyl hydroquinone. 8. The method of claim 7,
Re-crystallization of the filtrate of step e2-2) or step e2-3) with an organic solvent to repeat the process of separating and purifying the hydroquinone and 2-tert- butyl hydroquinone to prepare 2-tert- butyl hydroquinone Way. The method according to claim 7 or 8,
The organic solvent is any one or a mixture of two or more selected from xylene, dioxane, methyl isobutyl ketone and toluene or a method for producing 2-tert- butyl hydroquinone.
A method for preparing tert-butyl hydroanisole by reacting with dimethyl sulfate in 2-tert-butyl hydroquinone prepared in claim 1.