JPH0324071A - Purification of cyclic acetal - Google Patents

Abstract

PURPOSE:To purify a cyclic acetal in high purity by treating crude cyclic acetal with aqueous alkali and/or solid alkali hydroxide to remove the impurities which remain in the crude acetal and can be removed only with very difficulty through conventional processes simply in high efficiency. CONSTITUTION:Crude acetal is treated with an aqueous alkali of 50 to 70% concentration such as an aqueous solution of NaOH, KOH, Ca(OH)<2> and/or solid alkali hydroxide such as solid, granular or powdery NaOH, KOH, Ca(OH)2, preferably with an aqueous alkali followed by with solid alkali hydroxide to remove water, glycols, methanol, aldehydes or their polymers and other impurities in high efficiency to give cyclic acetal of high purity, which is used as an electrolyte solvent for electric cells.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for purifying cyclic acetals.

[Prior Art] Conventionally, as a method for purifying cyclic acetals, a method is known in which molecular sieves, anhydrous sulfur salt, etc. are added to crude acetals, the mixture is dehydrated, and then distilled.

[9. [Problems that Ming is trying to solve] However, when purifying assembled cyclic acetals using conventional methods, it is difficult to remove impurities such as glycols, methanol, aldehydes, and their polymers, making it difficult to obtain highly pure products. Therefore, an efficient refining method using fIn vehicles is desired.

[Means for Solving the Problems] The present inventors have arrived at the present invention as a result of intensive studies on a method for purifying cyclic acetals that does not have the above-mentioned problems.

That is, the present invention is a method for producing cyclic acetals, which is characterized in that crude cyclic acetals are treated with an aqueous alkali solution and/or a solid alkali hydroxide compound.

The alkaline aqueous solution used in the method for producing cyclic acetal sheaths of the present invention includes, for example, sodium hydroxide, potassium hydroxide,
Examples include aqueous solutions of calcium hydroxide. The concentration of the aqueous solution is preferably 50-70%.

Solid alkali hydroxide compounds include, for example, sodium hydroxide,
Solid, granular, etc. potassium hydroxide, calcium hydroxide, etc.
Powdered products are available.

The method of treating crude cyclic acetals with an aqueous alkaline solution is to add an aqueous alkali solution of 50 to 70% to the crude cyclic acetals in any proportion. After stirring for 1 to 2 hours, the alkaline aqueous solution is removed by liquid separation.

The weight ratio of the crude cyclic acetals to the aqueous alkali solution is preferably 3:1 to 1:3.

A method for treating crude cyclic acetals with a solid alkali hydroxide compound is to treat the crude cyclic acetals as they are or with an aqueous alkali solution, and then add a solid alkali hydroxide compound in any proportion. There is a method of removing alkali hydroxide after stirring for 1 to 5 hours.

Crude cyclic acetals can be produced by heating, stirring, and distilling glycols and aldehydes in the presence of a catalyst such as sulfuric acid.

Glycols used in the production of cyclic acetals include, for example, aliphatic or alicyclic glycols.

Examples of fatty glycols include ethylene glycol,
Propylene glycol, trimethylene glycol, 1
●3-butanediol, 1●2-bentanediol,
Examples of the alicyclic glycols include 1●2-hexanediol, 1●2-hebutanediol, 1●2-octanediol, and alicyclic glycols such as cyclopentane-1●2-dionole and cyclohexane-1●2-dionole.

As aldehydes, for example aliphatic, aromatic or heterocyclic aldehydes are used. Examples of aliphatic aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, propionaldehyde, butyraldehyde P, and inbutyraldehyde, and examples of aromatic aldehydes include benzaldehyde and salicylaldehyde. Examples of the heterocyclic aldehyde include furfural.

Examples of the catalyst include acids such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and para-toluenesulfonic acid, and ion exchange resins such as Amberlite 124 (Sumitomo Chemical).

The method for producing cyclic acetals includes, for example, adding glycols and aldehydes to a reactor at a molar ratio of preferably 3:
Prepare at a ratio of 1 to 1: 1, add a catalyst such as sulfuric acid in an amount of 3 to 10% of the total weight m of glycols and aldehydes, and add #j
It can be produced by distilling the cyclic acetal by heating it to a temperature higher than the boiling point of the cyclic acetal while stirring.

[Example] Hereinafter, the present invention will be further explained with reference to Examples, but the present invention is not limited thereto. In the following, parts and % indicate parts by weight and m% by weight, respectively.

Production Example 1 An example of producing a cyclic acetal is the following method for producing 1,3-dioxolane.

Ethylene glycol 298 in a 2L 4-turocolben equipped with a stirrer, thermometer, nitrogen inlet tube, and cooling takeout tube.
g (4.8 mol), rose formaldehyde 120 g (4.8 mol),
mol) and 11 g of sulfuric acid (97%) were added, and stirring and heating were started. When the temperature was raised to too''c, distillation of crude 1,3-dioxolane in the form of a colorless transparent liquid started from the condensate extraction tube.The temperature continued to rise after that, and it took 6 hours until 353 g had finished coming out.

Example 1 1.12 g of ifl1.3-dioxolane produced as in Production Example 1 was charged into a 3 L 4-turokolbene equipped with a stirrer, and 48% sodium hydroxide aqueous solution t&0.5K was added.
g was added thereto, stirred for 1 hour, allowed to stand for 20 minutes in a separatory funnel, and then separated to obtain 0.94 kg of 1,3-dioxolane.

Example 2 IKg of 1,3-dioxolane from Example 1 was charged into a 3L 4-turocolben equipped with a stirrer, 50g of granular sodium hydroxide was added, stirred for 3 hours, and filtered to give 0.98Kg.
1,3-dioxolane was obtained.

Example 3 I kg of 1,3-dioxolane from Example 2 was charged into a 3 L 4-turokorpen equipped with a stirrer, a thermometer and a distillation head, and distilled with stirring at a fulvene temperature of 75 to 80°C.
0.97 kg of 1,3-dioxolane having a boiling point of 76°C was obtained.

Comparative Example 1 IKg of crude 1,3-dioxolane produced as in Production Example 1, dehydrated with anhydrous sulfur salt, was charged into a 3 L 4-turokolbene equipped with a stirrer, thermometer and distillation head, while stirring. Distilled at Kolben temperature 75-80℃, boiling point 7
0.96 kg of 1,3-dioxolane at 6°C was obtained.

The purity of the 1,3-dioxolanes of Examples 1 to 3 and Comparative Example 1 by gas chromatographic analysis and the water content by Karl Fibscher method are shown in Table 1.

Table 1 A: Water B: Methanol C: (II Marine). D: Unit of ethylene glycol impurity: XIO” PP
M [Effects of the Invention] The cyclic acetals obtained by the purification method of the present invention can be obtained by treating the crude cyclic acetals with an aqueous alkali solution or a solid alkali hydroxide compound to remove moisture and glycols remaining in the crude cyclic acetals. It is highly pure because impurities such as , methanol, aldehydes, and their polymers have been removed.

Since it exhibits the above effects, it is useful as an electrolytic solvent for batteries.

Claims (1)

[Scope of Claims] 1. A method for purifying cyclic acetals, which comprises treating crude cyclic acetals with an aqueous alkali solution and/or a solid alkali hydroxide compound. 2. The purification method according to claim 1, characterized in that the crude cyclic acetals are treated with an aqueous alkali solution, the aqueous alkali solution is separated, and then the crude cyclic acetal is treated with a solid alkali hydroxide compound.