在超临界流体-离子液体双相系统中,对基的连续流水成型
Paul B Webb1, Murielle F Sellin, Thulani E Kunene
1School of Chemistry, University of St. Andrews, St. Andrews, Fife, KY16 9ST, Scotland.
Journal of the American Chemical Society
|December 11, 2003
概括
本研究介绍了一种使用超临界二氧化碳和离子液体的连续流水成型工艺. 这种方法有效地将产品从催化剂和溶剂中分离出来,实现高活性和稳定性.
科学领域:
- 化学工程是化学工程的重要组成部分.
- 催化剂是一种催化剂.
- 绿色化学 绿色化学
背景情况:
- 甲基化是生产化物的关键工业过程.
- 传统方法通常涉及恶劣的条件和困难的催化剂分离.
- 连续流系统在效率和安全方面提供了优势.
研究的目的:
- 为低挥发性烯开发一个连续流水合基化工艺.
- 为了研究使用超临界CO2和离子液体来增强反应和分离.
- 为了优化催化剂系统的高活性和稳定性.
主要方法:
- 使用了连续流反应堆系统.
- 使用离子液体作为催化剂溶剂.
- 使用超临界二氧化碳作为反应物和产品的运输介质.
- 研究了各种基于的催化剂,包括硫酸.
主要成果:
- 实现了高的催化剂周转频率 (高达500小时).
- 证明有效的产品分离,无需溶剂和催化剂.
- 识别了特定的离子液体 (1-基-3-甲基利米达二) 和C8+基链的三甲硫胺) 以获得最佳性能.
- 在最佳条件下观察到低出水 (低至0.012 ppm).
- 展示了连续运行数周,没有催化剂降解.
结论:
- 超临界流体-离子液体 (SCF-IL) 系统是一种可行且高效的连续甲基化方法.
- 仔细选择离子液体和催化剂连接体对于过程的成功至关重要.
- 该过程在产品纯度和催化剂可回收性方面提供了显著的优势.
相关概念视频
Formation of Halohydrin from Alkenes
An alkene, such as propene, reacts with bromine in the presence of water to yield a halohydrin. Halohydrins contain a halogen and a hydroxyl group attached to adjacent carbons. When the halogen is bromine, it is called a bromohydrin, while a chlorohydrin has chlorine as the halogen.
Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.
Electrophilic Addition to Alkynes: Hydrohalogenation
Electrophilic addition of hydrogen halides, HX (X = Cl, Br or I) to alkenes forms alkyl halides as per Markovnikov's rule, where the hydrogen gets added to the less substituted carbon of the double bond. Hydrohalogenation of alkynes takes place in a similar manner, with the first addition of HX forming a vinyl halide and the second giving a geminal dihalide.
Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Radical Substitution: Hydrogenolysis of Alkyl Halides with Tributyltin Hydride
Radical substitution reactions can be used to remove functional groups from molecules. The hydrogenolysis of alkyl halides is one such reaction, where the weak Sn–H bond in tributyltin hydride reacts with alkyl halides to form alkanes. Here, the reagent Bu3SnH yields tributyltin halide as a byproduct.
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...
The bonds formed in this reaction are stronger than the bonds broken, making it energetically favorable. The reaction follows a radical chain mechanism similar to radical halogenation reactions,...


