One-step Synthesis Of Oxo-crown Ethers By Catalytic Ring-enlargement Of γ-but-yrolactone Inserted By Alkylene Oxide

With a special macrolide ring, oxo-crown ethers have been widely applied in the fields of analysis, synthesis, catalysis and so on. So far, oxo-crown ethers are synthesized from the noncyclic raw materials such as oligoethylene glycols, oligoethylene glycols dihalide, dicarboxylic acid acyl halide, hydroxy carboxylate and so on via interamolecular or intramolecular cyclization as common methods. In this paper, a process for one-step synthesis of oxo-crown ethers by ring-enlargement reaction ofγ-butyrolactone inserted by ethylene oxide (propylene oxide) were studied in the presence of Al-Mg composite oxide catalysts. This novel synthesis route was simple and convenient. The effect of template on EO distribution of oxo-crown ethers was also investigated.The experimental conclusions were showed as following:(1) A one-step synthesis of oxo-crown ethers by catalytic ring-enlargement ofγ-butyrolactone inserted by ethylene oxide catalyzing by Mg-Al composite LE was investigated. The formation of oxo-crown ether structure in the above reaction was identified by FT-IR, ESI-MS HPLC-(ESI)MS. The catalyst LEs were screened out, and the optimum condition in enhancingγ-butyrolactone's convertion was researched mostly. Under the condition of LE-4 catalyst 1%, the initial pressure 0 MPa (gauge pressure), 155～165℃, 0.5～0.6 MPa and n(EO):n(GBL)=11:1, theγ-butyrolactone conversion was high up to 91.2%.(2) A one-step synthesis of oxo-crown ethers by ring-enlargement ofγ-butyrolactone inserted by propylene oxide catalyzed by Mg-Al composite LPs was investigated. The experimental results of FT-IR, HPLC, (ESI)-MS and UV showed that the oxo-crown ethers were formed. The optimum condition in enhancingγ-butyrolactone convertion was explored. Under the condition of 150～160℃, 0.5～0.6 MPa and n(PO):n(GBL)=13:1, theγ-butyrolactone conversion reached 90.4%.(3) Inspiration from template synthesis method in large cyclic compounds, the effect of template on EO distribution of oxo-crown ethers was investigated. The EO distribution was emphatically researched by adding template KI, KBr, KCl and acetonitril, respectively. The ESI-MS+ spectra of crude products confirmed that template reagent KCl exert excellent influence on the narrow EO distribution. By comparing reaction condition with(or without) template reagent (KCl), the experimental results showed that in the presence of template reagent, the reaction temperature reduced 10～20℃, theγ-butyrolactone's conversion increased 7.45% and catalytic activity increased 3.62% although the content of PEG increased 4.76%.