JP4387003B2 - Method for producing 3-alkyltetrahydrofuran - Google Patents

Description

【０００６】
（式中、Ｒはアルキル基を表す。）
で示される３−アルキル−３−ブテン−１−オール（以下、３−アルキル−３−ブテン−１−オール（Ｉ）と略称する）をヨウ素の存在下に環化反応させることを特徴とする３−アルキルテトラヒドロフランの製造方法を提供することにより達成される。
【０００７】
【発明の実施の形態】
上記一般式中、Ｒが表すアルキル基としては、例えばメチル基、エチル基、プロピル基、イソプロピル基、ｎ−ブチル基、イソブチル基、ｓｅｃ−ブチル基、ｔｅｒｔ−ブチル基などが挙げられる。
【０００８】
本発明において原料として用いる３−アルキル−３−ブテン−１−オール（Ｉ）、例えば３−メチル−３−ブテン−１−オールは、例えばホルムアルデヒドとイソブテンを加熱下で縮合させることにより容易に製造できる［アンゲバンテ・へミー・インターナショナル・エディション・イン・イングリッシュ（Ａｎｇｅｗ．Ｃｈｅｍ．Ｉｎｔ．Ｅｄ．Ｅｎｇｌ．）、第８巻、５５６頁（１９６９年）参照］。
【０００９】
ヨウ素は、工業的に製造され市販されているものをそのまま使用することができるが、昇華などの方法で精製したものを使用することが好ましい。ヨウ素の使用量は特に限定されないが、３−アルキル−３−ブテン−１−オール（Ｉ）１モルに対して０．００１〜１モルの範囲が好ましく、後処理の容易さの観点からは０．００１〜０．１モルの範囲がより好ましい。
【００１０】
反応は、溶媒の存在下に行うのが好ましい。使用する溶媒としては、反応に悪影響を及ぼさない限り特に制限はなく、例えば塩化メチレン、クロロホルム、四塩化炭素などのハロゲン化炭化水素；ジエチルエーテル、ジイソプロピルエーテル、ジブチルエーテル、テトラヒドロフラン、テトラヒドロピラン、４−メチルテトラヒドロピラン、１，４−ジオキサンなどのエーテル；ペンタン、ヘキサン、ヘプタン、オクタン、シクロヘキサン、シクロオクタンなどの飽和炭化水素；メタノール、エタノール、プロパノール、イソプロパノール、ブタノール、ｔ−ブタノールなどのアルコールなどが挙げられる。溶媒の使用量は特に限定されないが、通常３−アルキル−３−ブテン−１−オール（Ｉ）に対して０．０１〜１００重量倍の範囲が好ましく、０．１〜１０重量倍の範囲がより好ましい。
【００１１】
反応は、反応に不活性なガスの雰囲気下で行うのが好ましい。このような不活性ガスとしては、例えばヘリウム、窒素、アルゴンなどが挙げられる。これらの不活性ガスは１種類を単独で使用しても２種類以上を混合して使用しても差し支えない。
【００１２】
反応圧力には特に制限はなく、常圧下でも、また減圧下でも加圧下でも実施できる。反応装置・設備および操作性の観点からは、常圧下で実施することが好ましい。
【００１３】
反応温度は特に限定されないが、通常−８０〜２００℃の範囲であるのが好ましく、操作性および安全性の観点からは０〜１００℃の範囲がより好ましい。−８０℃以下では反応が極めて遅く進行する傾向となり、２００℃以上ではイソプレンなどの副生成物の生成が増大する傾向となる。
【００１４】
反応は、ヨウ素および溶媒を混合して所定温度とし、この溶液に３−アルキル−３−ブテン−１−オール（Ｉ）を滴下して撹拌することにより行うのが好ましい。
【００１５】
このようにして得られた３−アルキルテトラヒドロフランは、通常の有機化合物の単離・精製手段に用いられる方法と同様の方法で単離・精製することができる。例えば、反応液にチオ硫酸ナトリウムを加えてヨウ素を除去し、必要に応じて溶媒を除去した後、蒸留する。本発明の方法では水が副生しないので、例えば３−メチルテトラヒドロフランを製造する場合、蒸留するのみで高純度品を得ることができる。
【００１６】
【実施例】
以下、実施例により本発明をさらに詳細に説明するが、本発明はこれらの実施例によって何ら限定されるものではない。なお、各実施例において、反応の進行状況はガスクロマトグラフィー（使用カラム：ＰＥＧ−ＨＴ５％（カラム径４ｍｍ×カラム長３ｍ）、インジェクション温度：２１０℃、カラム温度：７０℃一定）で追跡した。
【００１７】
実施例１
温度計、滴下ロートおよびジムロートを装着した容量１００ｍｌの３口フラスコに、脱水した塩化メチレン２０ｍｌおよびヨウ素０．２５ｇ（１ミリモル）を入れ、系内を窒素置換した。この混合液に３−メチル−３−ブテン−１−オール１７．２ｇ（０．２モル）を２７℃で１時間かけて滴下し、滴下終了後、２７℃にて攪拌した。８時間後の反応成績は、３−メチル−３−ブテン−１−オールの転化率９８．２％、３−メチルテトラヒドロフランへの選択率９６．２％であった。この反応液にチオ硫酸ナトリウム１．４ｇを加えて、そのまま蒸留することにより、３−メチルテトラヒドロフラン１４．９ｇ（回収率９２％）を得た。
【００１８】
実施例２
実施例１において、塩化メチレン２０ｍｌの代わりにヘキサン２０ｍｌを用いた以外は実施例１と同様にして反応を行った。１２時間後の反応成績は、３−メチル−３−ブテン−１−オールの転化率８９．４％、３−メチルテトラヒドロフランへの選択率８９．９％であった。
【００１９】
実施例３
実施例１において、塩化メチレン２０ｍｌの代わりに四塩化炭素２０ｍｌを用いた以外は実施例１と同様にして反応を行った。１５時間後の反応成績は、３−メチル−３−ブテン−１−オールの転化率９３．３％、３−メチルテトラヒドロフランへの選択率９２．２％であった。
【００２０】
実施例４
実施例１において、ヨウ素の使用量を０．２５ｇ（１ミリモル）から２．５ｇ（１０ミリモル）とした以外は実施例１と同様にして反応を行った。３０分後の反応成績は、３−メチル−３−ブテン−１−オールの転化率９９．３％、３−メチルテトラヒドロフランへの選択率９７．２％であった。
【００２１】
【発明の効果】
本発明によれば、入手容易な原料より、水を副生することなく、３−アルキルテトラヒドロフランを工業的に有利に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing 3-alkyltetrahydrofuran. The 3-alkyltetrahydrofuran obtained in the present invention, such as 3-methyltetrahydrofuran, is useful as a raw material for a polyether polyol, which is a component of a thermoplastic polyurethane, and as a solvent.
[0002]
[Prior art]
Conventionally, as a method for producing 3-alkyltetrahydrofuran, for example, 3-methyltetrahydrofuran, (1) a method in which 2-methyl-1,4-butanediol is subjected to dehydration cyclization [Industrial and Engineering Chemical Research (Ind. Eng. Chem. Res., 33, 444-447 (1994)], (2) A method of hydrogenating methylsuccinic acid in the presence of a hydrous zirconium oxide catalyst using isopropanol as a hydrogen source [Bultin of Chemical Society Japan (Bull Chem. Soc. Jpn.), 65, 262-266 (1992)], (3) a method of hydroformylating methallyl alcohol, hydrogenating the resulting formyl body, and then dehydrating and cyclizing [ Journal Practice Hemy ( J. Prakt. Chem.), 314, 840-850 (1972)] is known.
[0003]
[Problems to be solved by the invention]
In the above method (1), it is difficult to obtain inexpensive and stable acquisition of 2-methyl-1,4-butanediol as a raw material. In the method (2), preparation of hydrous zirconium oxide used as a catalyst is complicated, and equivalent amount of acetone is by-produced from isopropanol used as a hydrogen source. In the method (3), the rhodium compound used as a catalyst for the hydroformylation reaction is expensive, and the raw material methallyl alcohol is not industrially produced and is difficult to obtain easily and inexpensively. Have a problem. Further, in the above methods (1) to (3), all of 3-methyltetrahydrofuran is obtained as a mixture with water produced as a by-product. However, since 3-methyltetrahydrofuran azeotropes with water, it can be obtained simply by distillation. Dehydrated high-purity 3-methyltetrahydrofuran cannot be obtained. In order to dehydrate, for example, dissolved water must be extracted and removed with a high-concentration sodium hydroxide aqueous solution and then distilled again. Have the problem.
Therefore, an object of the present invention is to provide a method capable of industrially advantageously producing 3-alkyltetrahydrofuran such as 3-methyltetrahydrofuran without using water as a by-product from readily available raw materials.
[0004]
[Means for Solving the Problems]
According to the invention, the above object is achieved by the general formula (I)
[0005]
[Chemical formula 2]

[0006]
(In the formula, R represents an alkyl group.)
A cyclization reaction of 3-alkyl-3-buten-1-ol represented by the following (hereinafter abbreviated as 3-alkyl-3-buten-1-ol (I)) is carried out in the presence of iodine. This is accomplished by providing a process for producing 3-alkyltetrahydrofuran.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the above general formula, examples of the alkyl group represented by R include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, and a tert-butyl group.
[0008]
The 3-alkyl-3-buten-1-ol (I) used as a raw material in the present invention, such as 3-methyl-3-buten-1-ol, is easily produced by, for example, condensing formaldehyde and isobutene under heating. Yes [see Angew. Chem. Int. Ed. Engl., Vol. 8, 556 (1969)].
[0009]
Although what is manufactured and marketed industrially can be used as it is for iodine, it is preferred to use what was refined by methods, such as sublimation. The amount of iodine used is not particularly limited, but is preferably in the range of 0.001 to 1 mol with respect to 1 mol of 3-alkyl-3-buten-1-ol (I), and is 0 from the viewpoint of ease of post-treatment. A range of 0.001 to 0.1 mol is more preferable.
[0010]
The reaction is preferably carried out in the presence of a solvent. The solvent to be used is not particularly limited as long as it does not adversely influence the reaction. For example, halogenated hydrocarbons such as methylene chloride, chloroform and carbon tetrachloride; diethyl ether, diisopropyl ether, dibutyl ether, tetrahydrofuran, tetrahydropyran, 4- Examples include ethers such as methyltetrahydropyran and 1,4-dioxane; saturated hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane and cyclooctane; alcohols such as methanol, ethanol, propanol, isopropanol, butanol and t-butanol. It is done. Although the usage-amount of a solvent is not specifically limited, Usually, the range of 0.01-100 weight times is preferable with respect to 3-alkyl-3-buten-1-ol (I), and the range of 0.1-10 weight times is preferable. More preferred.
[0011]
The reaction is preferably performed in an atmosphere of a gas inert to the reaction. Examples of such an inert gas include helium, nitrogen, and argon. These inert gases may be used alone or in combination of two or more.
[0012]
There is no restriction | limiting in particular in reaction pressure, It can carry out even under a normal pressure, under reduced pressure, and pressurization. From the viewpoint of the reaction apparatus / equipment and operability, the reaction is preferably carried out under normal pressure.
[0013]
Although reaction temperature is not specifically limited, Usually, it is preferable that it is the range of -80-200 degreeC, and the range of 0-100 degreeC is more preferable from a viewpoint of operativity and safety | security. At −80 ° C. or lower, the reaction tends to proceed very slowly, and at 200 ° C. or higher, the production of by-products such as isoprene tends to increase.
[0014]
The reaction is preferably carried out by mixing iodine and a solvent to a predetermined temperature, and dropping 3-alkyl-3-buten-1-ol (I) into this solution and stirring.
[0015]
The 3-alkyltetrahydrofuran thus obtained can be isolated and purified by a method similar to the method used for usual organic compound isolation and purification means. For example, sodium thiosulfate is added to the reaction solution to remove iodine, and the solvent is removed as necessary, followed by distillation. Since water is not by-produced in the method of the present invention, for example, when producing 3-methyltetrahydrofuran, a high-purity product can be obtained only by distillation.
[0016]
【Example】
EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited at all by these Examples. In each example, the progress of the reaction was monitored by gas chromatography (column used: PEG-HT 5% (column diameter 4 mm × column length 3 m), injection temperature: 210 ° C., column temperature: constant 70 ° C.).
[0017]
Example 1
20 ml of dehydrated methylene chloride and 0.25 g (1 mmol) of iodine were placed in a three-necked flask with a capacity of 100 ml equipped with a thermometer, a dropping funnel and a Dim funnel, and the inside of the system was purged with nitrogen. To this mixed solution, 17.2 g (0.2 mol) of 3-methyl-3-buten-1-ol was added dropwise at 27 ° C. over 1 hour, and the mixture was stirred at 27 ° C. after completion of the addition. The reaction results after 8 hours were a conversion rate of 3-methyl-3-buten-1-ol of 98.2% and a selectivity to 3-methyltetrahydrofuran of 96.2%. To this reaction solution, 1.4 g of sodium thiosulfate was added and distilled as it was to obtain 14.9 g of 3-methyltetrahydrofuran (recovery rate 92%).
[0018]
Example 2
In Example 1, the reaction was performed in the same manner as in Example 1 except that 20 ml of hexane was used instead of 20 ml of methylene chloride. The reaction results after 12 hours were a conversion rate of 3-methyl-3-buten-1-ol of 89.4% and a selectivity to 3-methyltetrahydrofuran of 89.9%.
[0019]
Example 3
In Example 1, the reaction was conducted in the same manner as in Example 1 except that 20 ml of carbon tetrachloride was used instead of 20 ml of methylene chloride. The reaction results after 15 hours were a conversion rate of 3-methyl-3-buten-1-ol of 93.3% and a selectivity to 3-methyltetrahydrofuran of 92.2%.
[0020]
Example 4
In Example 1, the reaction was performed in the same manner as in Example 1 except that the amount of iodine used was changed from 0.25 g (1 mmol) to 2.5 g (10 mmol). As for the reaction results after 30 minutes, the conversion of 3-methyl-3-buten-1-ol was 99.3%, and the selectivity to 3-methyltetrahydrofuran was 97.2%.
[0021]
【The invention's effect】
According to the present invention, 3-alkyltetrahydrofuran can be industrially advantageously produced from readily available raw materials without producing water as a by-product.

Claims (1)

Formula (I)

(In the formula, R represents an alkyl group.)
A process for producing 3-alkyltetrahydrofuran, which comprises cyclizing the 3-alkyl-3-buten-1-ol represented by formula (I) in the presence of iodine.