JPS6256446A - Purification of 2,2,2-trifluoroethanol - Google Patents

Abstract

PURPOSE:To purify 2,2,2-trifluoroethanol containing an S component as an impurity, by adding large excess H2O2 to the crude 2,2,2-trifluoroethanol, heating the mixture under refluxing, decomposing residual hydrogen peroxide, adding an alkali to the product to convert the S component to non-volatile material and distilling the reaction product. CONSTITUTION:Crude 2,2,2-trifluoroethanol containing a sulfur compound component as an impurity is heated under refluxing in the presence of large excess hydrogen peroxide based on the sulfur compound, residual hydrogen peroxide is decomposed, an alkali (preferably sodium hydroxide) is added to the product to convert the sulfur component to non-volatile material, and the reaction mixture is distilled to obtain purified 2,2,2-trifluoroethanol. To prevent the residue of hydrogen peroxide and its explosion hazard, it is preferable to add a reducing substance (e.g. sodium bisulfite) to the system after the heat refluxing and prior to the addition of the alkali, thereby decomposing the residual hydrogen peroxide. A high-quality colorless product free from sulfur odor can be produced by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a method for purifying 2,2,2-trifluoroethanol containing a sulfur component as an impurity.

2.2.2-Trifluoroethanol (CF30Hz
Because OH) is extremely thermally stable, it is used as a heat medium for medium-low temperature ranges and as a working heat medium for waste heat recovery in large diesel engines, and is also used as a fluorine-containing acrylic material used as a sheath material for optical fibers. Polymer (2,2,2
- derived from trifluoroethanol and acrylic acid), is used as a raw material for phosphazene polymers with excellent heat resistance, oil resistance, and flame retardancy, and is a material that has attracted attention in recent years.

<Prior art and its problems> 2.2. Several methods for producing 2-trifluoroethanol are known. In it, 1-chloro-2,2,2-trifluoroethane (CF3CH2C1) and potassium acetate dissolved in sulfolane solvent in an autoclave were added for 15 minutes.
2,2.2-) Lifluoroethyl acetate (OF3C) I20 COC), a precursor of 2,2.2-trifluoroethanol, is heated to 0-260°C.
A method is known in which 2,2,2-trifluoroethanol is obtained by hydrolyzing 2,2,2-trifluoroethanol in a high yield. Said 2,
2.2-) The manufacturing method of lifluoroethyl acetate is as follows:
It was disclosed in Japanese Patent Application Laid-Open No. 10-1208j5, and also filed in Japanese Patent Application No. 5
9-132708.59-1901316. 2,2.2-trifluoroethyl acetate is easily hydrolyzed to give 2.2.2-trifluoroethanol.

However, although the 2,2,2-trifluoroethanol produced by the above method and purified by distillation is recognized as pure by gas chromatography analysis, it has a slight sulfur odor, and furthermore, when exposed to sunlight for a long time, it turns light brown. It has been observed that it becomes colored. Therefore, 2,2.2-1 refluoroethanol obtained by purification by distillation is still unsuitable for practical use.

Means for Solving the Problem> The present inventors have developed 2,2.2-) refluoroethanol that has no sulfur odor and does not cause coloring.
We considered a method to purify it into trifluoroethanol, but
The odor was presumed to be from a sulfur component produced by the decomposition of sulfolane used in the synthesis of 2,2.2-)lifluoroethyl acetate, and when quantified by chemical analysis, it was determined that the odor was 2,2.2-) produced by the above method. It has been found that 2-trifluoroethanol contains several tens to hundreds of ppm of sulfur component in terms of sulfate radicals (5O42-). It has been found that the above problem can be solved by oxidizing this sulfur component and removing it as a non-volatile sulfur compound.

<Configuration of the Invention> According to the present invention, 2,2 containing a sulfur compound as an impurity
．． 21 Add a large excess of hydrogen peroxide to the sulfur compound to refluoroethanol, heat it under reflux conditions (hereinafter referred to as reflux heating), decompose the residual hydrogen peroxide, and add alkali to make the sulfur component non-volatile. 2,2.2-) A method for purifying refluoroethanol is provided, comprising converting it into a chemical product and then distilling it. In the process of the invention, in order to avoid residual hydrogen peroxide and the risk of explosion thereof after heating under reflux, it is preferred to add a reducing substance to decompose the residual hydrogen peroxide prior to the addition of alkali.

Suitable reducing substances include, but are not limited to, sodium bisulfite, and the most preferred alkali is sodium hydroxide. In the process of the present invention, the hydrogen peroxide used is a commercially available 30% aqueous solution. In view of the amount of sulfur compounds in 2,2.2-trifluoroethanol mentioned above, the amount of hydrogen peroxide used is 2,2.2.
2-) The time required for the solubilization treatment with hydrogen peroxide, which may be about 10% by weight as a 30% aqueous solution based on refluoroethanol, varies depending on the amount of hydrogen peroxide added, but is preferably carried out for 48 hours or more.

In the method of the present invention, the amount of sulfur-based impurities is within the detection limit F
(1 ppm), and the recovery rate is 95% or more.

Although the nature of sulfur compounds as impurities in 2, 2.2-) refluoroethanol to which the method of the present invention is applied is still not clear, examples show that they are significantly reduced by the hydrogen peroxide treatment according to the present invention. As demonstrated by

<Embodiment> Example 1 JP-A-120835 (Japanese Patent Application No. 58-228212)
2,2.2-) Lifluoroethyl acetate synthesized according to the method described in 2.
-Trifluoroethanol was obtained. This 2,2.2-
) Refluoroethanol has a sulfur odor and turns pale brown in the throat for 3 days when exposed to sunlight.

Approximately 1 ml of this 2,2,2-trifluoroethanol was accurately weighed and diluted with pure water to make a total volume of 10 ml. To this solution were sequentially added 3% hydrogen peroxide solution, 01, 1% aqueous sodium hydroxide solution, and 1.0 ml of saturated bromine water. This solution was evaporated to dryness on a water bath, and the remaining liquid was added with 2.01 g of 35% concentrated hydrochloric acid.
was added, and the mixture was dried again on a hot water bath. Distilled water was added to this dried product to dissolve it, and the total volume was made up to 10ml. This solution was processed using ion chroma I/graph method (equipment used: Dionex
Ion Chromatographo, Column: A
nian Concentrator Part, 1
1030824゜Anion 5eparator P
art 1030B2? ), it was confirmed that 7.7 ppm of sulfur was present as sulfate radicals.

Pour 100 g of the same 2,2.2-trifluoroethanol into a flask equipped with a stirrer and a reflux condenser, and add 30 g of trifluoroethanol.
' was added with 4.0 l of hydrogen peroxide aqueous solution, heated under reflux, and
After 6 hours and 32 hours, 30% hydrogen peroxide solution was added. OLlIl was added, and the mixture was heated under reflux for a total of 48 hours, and then allowed to cool. Then 48% potassium hydroxide aqueous solution 15
After adding m1, rectification was performed to collect a fraction with a boiling point of 70 to 95°C. This fraction does not have a sulfuric odor and does not become colored at all even when exposed to sunlight for a week.

As a result of quantifying the sulfur component in the same manner as before the treatment, it was less than 1 ppm in terms of Vi and acid radicals.

Examples 2 to 6 Using 2, 2.2-) refluoroethanol with different sulfur content, and partially changing the hydrogen peroxide treatment conditions as shown in the table below, and adding sodium sulfite. The same operation as in Example 1 was repeated except that a step of decomposing excess hydrogen peroxide was added. The conditions and results are shown in the following table along with those of Example 1.

<Effects of the Invention> The removal of sulfur components from 2,2.2-) refluoroethanol according to the present invention is simple and extremely effective. There is little loss of 2,2,2-trifluoroethanol during treatment, and it has high industrial utility value.

Claims (1)

[Claims] 1. To 2,2,2-trifluoroethanol containing sulfur compounds as impurities, hydrogen peroxide in large excess relative to the sulfur compounds is added and heated under reflux, and then an alkali is added and distilled. A method for purifying 2,2,2-trifluoroethanol, which comprises: 2. The method according to claim 1, wherein the alkali is sodium hydroxide. 3. To 2,2,2-trifluoroethanol containing sulfur compounds as impurities, add a large excess of hydrogen peroxide to the sulfur compounds and heat under reflux, then add a reducing substance to remove residual hydrogen peroxide. A method for purifying 2,2,2-trifluoroethanol, which comprises decomposing it and then adding an alkali and distilling it. 4. The method according to claim 3, wherein the reducing substance is sodium bisulfite and the alkali is sodium hydroxide.