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外観
無色～黄褐色, 澄明の液体
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溶解性
水, エタノール, アセトンに易溶。エタノール及びアセトンに極めて溶けやすく、水に溶けやすい。
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用途
2-MeTHFは、主にTHFを代替する高沸点溶媒として用いられる。またリチウムイオン二次電池の電解液成分や代替燃料としても用いられる。低温反応の溶媒としても重要である。2-MeTHFは結晶ではなくガラス状態を取るため、しばしば-196°Cにおける分光学的研究で溶媒として用いられる。
他に知られている応用としては、グリニャール反応における溶媒が挙げられる。これは酸素原子がグリニャール試薬中のマグネシウムイオンに配位することが可能であり、また共沸により系中を乾燥できるためである。2-MeTHFに水を加え分液すると、きれいに相分離する。THFの代替溶媒としては一般的であるが、コスト高になる。
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説明
2-Methyltetrahydrofuran (MeTHF or 2-MTHF) is a bio-based solvent that is recognized as the most favorable of ether solvents. The relatively high boiling point (80?C) and low melting point (-137?C) provide a broad temperature range for a myriad of processing conditions. It is a potential greener solvent alternative for organic synthesis. It shows resistance to reduction by lithium making it a promising candidate as electrolytes in lithium batteries. Its polarity and Lewis base strength is intermediate between tetrahydrofuran (THF) and diethyl ether. The ring opening reaction of 2-MTHF has been studied using acid chloride and iodide.
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化学的特性
Colorless liquid; ether-like odor. Solubility in waterincreases with a decrease in temperature. Freelysoluble in most organic solvents.
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使用
2-Methyltetrahydrofuran acts as a solvent in organic synthesis. It is considered as a replacement for terahydrofuran due to its higher reaction temperature and easy separation after reaction. It is also useful in the electrolyte formulation for secondary lithium electrodes and as a component in alternative fuels. Further, it is used as a solvent for spectroscopic studies at -1960C. It also acts as a solvent for Grignard reagent in organometallic reactions. In addition to this, it plays an important role as a motor fuel.
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一般的な説明
This product is a biorenewable and thus aligns with "Safer Solvents and Auxiliaries" and "Use of Renewable Feedstocks".
2-Methyltetrahydrofuran (2-MTHF), a 2-methyl substituted tetrahdrofuran, is a biomass derived solvent. It is a potential greener solvent alternative for organic synthesis. It shows resistance to reduction by lithium making it a promising candidate as electrolytes in lithium batteries. Its polarity and Lewis base strength is intermediate between tetrahydrofuran (THF) and diethyl ether. The ring opening reaction of 2-MTHF has been studied using acid chloride and iodide to form secondary chlorides and primary iodides respectively. On long term storage, tetrahydrofuran forms organic peroxides. This process can be suppressed by adding butylated hydroxytoluene (BHT) as a stabilizer. BHT removes the free radicals required for the peroxide formation.
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危険性
Flammable, dangerous fire risk.
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純化方法
Likely impurities are 2-methylfuran, methyldihydrofurans and hydroquinone (stabiliser, which is removed by distillation under reduced pressures). It is washed with 10% aqueous NaOH, dried, vacuum distilled from CaH2, passed through freshly activated alumina under nitrogen, and refluxed over sodium metal under vacuum. Store it over sodium. [Ling & Kevan J Phys Chem 80 592 1976.] Distil it from sodium under vacuum, and store it with sodium-potassium alloy (this treatment removes water and prevents the formation of peroxides). Alternatively, it can be freed from peroxides by treatment with ferrous sulfate and sodium bisulfate, then solid KOH, followed by drying with, and distilling from, sodium, or type 4A molecular sieves under argon. It may be difficult to remove *benzene if it is present as an impurity (can be readily detected by its ultraviolet absorption in the 249-268nm region). [Ichikawa & Yoshida J Phys Chem 88 3199 1984.] It has also been purifed by percolating through Al2O3 and fractionated collecting fraction b 79.5-80o. After degassing, the material is distilled onto degassed molecular sieves, then distilled onto anthracene and a sodium mirror. The solvent is then distilled from the green solution onto potassium mirror or sodium-potassium alloy, from which it is distilled again. [Mohammad & Kosower J Am Chem Soc 93 2713 1971.] It should be stored in the presence of 0.1% of hydroquinone or 2,6-di-tert-butyl –p-cresol as stabiliser. The R(+)-enantiomer has b 78-80o/atm and []D +27.5o (neat), and the S(-)-enantiomer has b 86o/atm and [] D -27.0o (neat) [Iffland & Davis J Org Chem 42 4150 1977, Gagnaire & Butt Bull Soc Chim Fr 312 1961, Beilstein 17 III/IV 60, 17/1 V 78.] HARMFUL VAPOURS.
