JPH053458B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for purifying trans-1,2-diaminocyclohexane. [Prior art] Although the trans and cis forms of 1,2-diaminocyclohexane have slightly different melting points (trans form: 15°C, cis form: 2°C), other physical properties are very similar. Therefore, separation by conventional methods such as distillation or chromatography is difficult. Therefore, a conventional method has been used in which divalent nickel ions are applied to crude 1,2-diaminocyclohexane to precipitate both the trans and cis isomers as respective nickel complexes (Japanese Patent Laid-Open No. 111544/1983), or 1,2-diaminocyclohexane is - A method is known (Japanese Patent Publication No. 45-29655) in which diaminocyclohexane is reacted with an organic dibasic acid to precipitate the trans isomer as a dibasic acid salt. [Problems to be Solved by the Invention] However, in the above-mentioned known examples, 1,2-diaminocyclohexane is crystallized as a complex salt or an organic acid salt, so it is easily affected by impurities in the raw materials and solvent, and the usable solvent is limited. Limited. Furthermore, methods using metal salts have the problem of post-treatment, that is, waste liquid treatment. [Means for Solving the Problems] Therefore, the present inventors conducted extensive research aimed at establishing a purification method for 1,2-diaminocyclohexane that solved the above problems, and as a result, crude 1,2-diaminocyclohexane was obtained. The resulting crude 1,2-bis(acetamido)cyclohexane is crystallized in an organic solvent or water to give trans-
Precipitating and separating 1,2-bis(acetamido)cyclohexane and the separated trans-
The present invention was completed based on the discovery that a different method for hydrolyzing 1,2-bis(acetamido)cyclohexane can be used. The configuration, embodiments, and effects of the present invention will be described below. In the present invention, crude 1,2-diaminocyclohexane is composed mainly of trans-1,2-diaminocyclohexane, and also contains amine compounds other than the above-mentioned amines, such as cis-1,2-diaminocyclohexane, hexamethylene diamine, It refers to a mixture containing an amine compound containing one or more selected from hexamethyleneimine, 2-methylpentamethylenediamine, and 2-(aminomethyl)cyclopentylamine, water, and the like. Since this compound is produced as a by-product in the manufacturing process of hexamethylene diamine, for example, it is preferably used in the present invention. Next, the mixture is acetylated by acting with acetyl chloride or acetic anhydride to obtain crude 1,2-bis(acetamido)cyclohexane. Acetylation is carried out under conditions known per se, for example, by adding acetic anhydride to chloroform containing the above mixture and stirring at room temperature for about 1 hour. The crude 1,2-bis(acetamido)cyclohexane thus obtained is crystallized. Crystallization is carried out using organic solvents or water. Examples of organic solvents include alcohols such as methanol and ethanol, esters such as ethyl acetate, ketones such as acetone, halogenated hydrocarbons such as chloroform and dichloromethane, lower fatty acids such as acetic acid, and mixed solvents thereof. . Preferably water,
These are methanol, ethanol, chloroform, acetone and ethyl acetate. Crystallization may be performed by either recrystallization or concentration crystallization, but it is important to separate the trans isomer from the crystallization system before the cis isomer is precipitated. The timing of separation is determined depending on the type of solvent. The trans-1,2-bis(acetamido)cyclohexane obtained from the crystallization system is then hydrolyzed using conventional methods and conditions. Preferably, this is carried out by dissolving the solution in an aqueous hydrochloric acid solution and refluxing it for about 5 to 10 hours. Next, an example will be described. [Example] Example 1 Commercially available (Tokyo Kasei Reagent, 38% trans form, cis form
11.5 g of 1,2-diaminocyclohexane (60%)
Add acetic anhydride to a solution of 200ml of chloroform.
24.5 g was added dropwise over 30 minutes while stirring at room temperature. After the addition, the mixture was stirred at room temperature for an additional hour, and the reaction mixture was washed with 100 ml of 20% aqueous sodium hydroxide solution. The organic layer was concentrated to dryness under reduced pressure to obtain 19.9 g of crude 1,2-bis(acetamido)cyclohexane. The content of trans isomer in this product was 39% (hereinafter referred to as acetylation reaction). 2.00 g of crude 1,2-bis(acetamido)cyclohexane was heated and dissolved in 7.3 g of water, and then gradually cooled to room temperature. The generated precipitate was filtered, dried, and then subjected to gas chromatography (Thermon-3000,
3.0mmx1.0m, 215℃, 9 minutes for trans form, cis form
11 minutes), the content of trans isomer was
It was 85%. The yield was 0.54 g (above crystallization operation). 75.9 g of trans-1,2-bis(acetamido)cyclohexane (trans isomer content 99%) obtained by crystallization was dissolved in 600 ml of 2N hydrochloric acid.
It was refluxed for 9 hours. After cooling, the mixture was washed with chloroform and concentrated under reduced pressure. 200 g of a 25% aqueous sodium hydroxide solution was added little by little to the residue while cooling with ice, and the resulting mixture was extracted with chloroform.
The organic layer was dried over anhydrous sodium sulfate, concentrated under reduced pressure, and further distilled under reduced pressure (80°C/12mmHg).
As a result, 36.1 g of trans-1,2-diaminocyclohexane (trans isomer content 99%) was obtained (the above hydrolysis operation). Example 2 2.00 g of crude 1,2-bis(acetamido)cyclohexane obtained in the acetylation reaction of Example 1 was subjected to the same crystallization operation as in Example 1 using various solvents. The analysis results of the crystals are shown in the table.

[Table] Example 3 1,2-diaminocyclohexane content is 40~
An experiment was conducted in accordance with Example 1 using a mixture containing 60% of the amine compound and the remainder consisting of an amine compound other than the above-mentioned amine compound. 5.7 g of the crude 1,2-diaminocyclohexane
Add acetic anhydride to a solution of 150ml of chloroform.
20.4 g was added dropwise over 30 minutes while stirring at room temperature. After the addition, the mixture was stirred at room temperature for an additional hour, and the reaction mixture was washed with 100 ml of 20% aqueous sodium hydroxide solution. The organic layer was concentrated under reduced pressure and then recrystallized in chloroform. When the obtained precipitate was filtered and dried and analyzed by gas chromatography, the content of trans isomer was 99.7%. The yield was 3.8g. [Effects of the Invention] The present invention exhibits the following effects. That is, 1,
Trans-1,2-diaminocyclohexane can be efficiently separated and purified from crude 1,2-diaminocyclohexane containing amine compounds other than 2-diaminocyclohexane. Furthermore, there are many types of solvents that can be used in the crystallization operation, and therefore there is a large degree of freedom in the process.

Claims (1)

[Claims] 1. Acetylating crude 1,2-diaminocyclohexane, crystallizing the obtained crude 1,2-bis(acetamido)cyclohexane in an organic solvent or water to precipitate trans-1,2-bis(acetamido)cyclohexane. , and hydrolyzing the separated trans-1,2-bis(acetamido)cyclohexane.