JPS6281341A - Production of 2,5-di-tert-butylhydroquinone - Google Patents

Abstract

PURPOSE:To obtain the titled compound useful as a non-staining antioxidant for plastics, rubbers, lubricating oils, etc., in high purity, by extracting a reaction mixture prepared by alkylating hydroquinone with warm water and recrystallizing the extraction residue with toluene. CONSTITUTION:A reaction mixture obtained by alkylating hydroquinone with isobutene in the presence of phosphoric acid catalyst is extracted with warm water to separate 2-tert-butylhydroquinone (TBHQ). Toluene in an amount of 3-5 times based on the extraction residue is added to the extraction residue consisting essentially of 2,5-di-tert-butylhydroquinone (DTBHQ) and the mixture is heated to 100-150 deg.C and then cooled to separate the deposited crystals from the mother liquor and afford the aimed DTBHQ of high purity without containing sulfuric acid, etc., together with TBHQ of high added value with good productivity. Only recrystallization equipment with toluene may be additionally installed for this method and impurities can be readily treated by incineration, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing 2 + 5-tert-butylhydroquinone. 2,5-ter
T-Butylhydroquinone is a useful compound widely used as a non-staining antioxidant for plastics, rubber, lubricating oils, etc. Furthermore, in recent years, it has been used as a raw material for organic reactions that utilize its chemical structure, and there is a demand for its high purity.

[Conventional technology]

2.5-Di-tert-butylhydroquinone is synthesized by t-f tyl alcohol or isozotenphalkylation of hydroquinone, and this synthesis reaction uses zinc chloride (US Pat. No. 2,511,193) as a catalyst. or 50-80% sulfuric acid (U.S. Patent No. 2,832,808)
However, a method using a sulfuric acid catalyst is generally used because of the ease of post-treatment such as separation of the catalyst from the product. In other words, gaseous isobutyne is introduced into hydroquinone separated in a sulfuric acid water bath solution, and the reaction product is separated from the sulfuric acid aqueous solution by filtration. Washed and unreacted raw materials, by-products,
Remove the attached sulfuric acid and dry to remove the target 2.5-note.
ert-zotylhydroquinone is obtained.

[Problem that the invention seeks to solve]

However, the cost of the conventional manufacturing method as mentioned above is only that there is a purification step in which the reaction product is repeatedly washed with water or hot water, and such a purification step alone cannot produce 2,5-di-te.
r It is not possible to sufficiently remove impurities incorporated into the crystals of t-butylhydroquinone and by-products that are poorly soluble in hot water, and these substances may cause coloring of the product. Difficult to obtain di-tert-butylhydroquinone - IJ). Incidentally, M of 2,5-di-tert-butylhydroquinone obtained by the conventional method
ll is approximately 99.0%, and the M point is 210 to 212°C. Furthermore, if sulfuric acid used as a catalyst remained in the product, there was a risk that 2,5-tert-butylhydroquinone would decompose during use.

[Means and effects for solving the problems] According to the method of the present invention, '1-tert-butylhydroquinone (hereinafter referred to as T
Main components of raffinate produced by-product during production (denoted as BHQ)
High purity DTB) IQ can be obtained by isolating a certain 2,5-di-tert-butylhydroquinone (hereinafter referred to as DTBHQ) by a recrystallization method using toluene.

TBIIQ is produced, for example, by alkylating hydroquinone with isobutyne in the presence of a phosphoric acid catalyst, but even with the best selectivity, only a few mol% of DTB is produced.
HQ is a byproduct. This reaction mixture is made into a water slurry, and when t% TBHQ is extracted with hot water, a raffinate containing DTBHQ as a main component is obtained.

Add 6 to 5 times the amount of toluene to this raffinate, and
It is heated to 0-150°C, then cooled and the crystallized crystals are separated from the mother liquor by a suitable method. DTBHQ of higher purity can be obtained by removing the liquid from this crystallization mother liquor as thoroughly as possible. Toluene adhering to the separated crystals is azeotropically removed with water. When the slurry thus obtained is cooled, dehydrated, and dried, highly pure D T B HQ is obtained. Toluene is recovered from the crystallization mother liquor separated from the crystals by azeotropy with water and used as a recrystallization solvent. Here ff1) When the mother liquor is cooled to room temperature after toluene distillation, the azeotropic residue solidifies and the whole becomes slurry-like. This slurry is dehydrated by an appropriate method, and the resulting solids are incinerated.

The present invention will be illustrated by the following examples.

Example: In a reactor with a volume of t3 m', hydroquinone asoxp, 60
% phosphoric acid 149KP and toluene 15001,
Heat to 120°C. Add 244 KP of Inbuten to this.
Add it over time. After the addition of isobutyne was completed, the reaction mixture was cooled to 100 °C, left to stand for 30 minutes, the toluene layer was decanted and transferred to another stirring tank, phosphoric acid and unreacted hydroquinone were removed by washing with water, and then Toluene is removed by azeotroping with water. The product thus obtained is cooled to 70-80°C to form a water slurry, and TBHQ is extracted with hot water.

The raffinate obtained after extraction is rich in DTBHQ and D
TBHQ69.4 Toshiki%, TBHQ6.9% by weight, water 1
0.0 weight 1%, other +! Each item consists of 13.7% by weight.

Add 2.01 l of toluene to this raffinate 455 K9,
Heat to 40°C to dissolve. Immediately after the temperature reaches 140°C and melts, it is cooled to room temperature to precipitate crystals.

After removing 1.9 m" of toluene by filtration, water is added to the resulting cake and heated to remove the toluene azeotropically with the water. When the temperature reaches the boiling point of water, the mixture Cool to room temperature, dehydrate, and dry. Purity 99.8%, melting point 2.
DTBHQ 300 Ky of 14-218°C is obtained. The recovery rate of DTBHQ in the raffinate is 95%. The filtered toluene is azeotroped with water to recover 1.85 m'' of toluene, yielding 2 as an azeotropic residue 96.

〔Effect of the invention〕

According to the method of the present invention, (1) 2-t with higher added value
Ert-butylhydroquinone is produced as a by-product, and the raw materials hydroquinone and isobutyne can be used effectively; (2+2
.

It has higher fertility compared to the conventional method, which involves the production of only 5-di-tert-butylhydroquinone; (3) Extraction with hot water removes water-soluble impurities, and recrystallization with toluene removes oil-soluble impurities. Highly purified 2,5-tert-butylhydroquinone containing no acid is obtained; (4) Hot water extraction is performed using 2-tert
Equipment for t-butylhydroquinone can be used, and production equipment can be easily constructed by simply adding equipment for recrystallization with toluene; (5) Removed impurities can be easily disposed of by incineration, etc. .

Claims (1)

[Claims] 2, characterized in that the reaction mixture obtained by alkylation of hydroquinone is extracted with hot water, the raffinate consisting of 2,5-di-tert-butylhydroquinone is recrystallized with toluene, and separated from the mother liquor; Method for producing 5-di-tert-butylhydroquinone.