Iodine → 3-Octadecylthiophene

참여 물질

반응 조건

반응 단계

3-n-octadecylthiophene was prepared as set forth in Kumda et al Bull. Chem Soc. Jpn. 1976, 49, 1958-1969 and Tetrahedron 1982, 38, 3347-3354. A dry 1000 mL 2 neck flask was charged with Mg ribbon (3.34 g, 137 mmol) under N2 followed by addition of ˜200 mL of anhydrous Et2O. The flask was cooled in an ice bath (0° C.). In a separate 500 mL flask 40 g (120 mmol) of n-C18H37Br was dissolved in ˜200 mL of anhydrous Et2O under N2. The Et2O solution of n-C18H37Br was slowly transfer into the flask containing the Mg ribbon, with sonication, stirring, and addition of I2 to initiate Grignard. After complete addition of n-C18H37Br to the Mg the reaction mixture was allowed to stir overnight to allow for complete formation of the Grignard reagent (n-C18H37MgBr). A dry 1000 mL 3-neck flask was charged with 0.540 g of 1,3-Bis(diphenylphosphino)propane nickel (II) chloride was added under nitrogen followed by ˜100 mL of anhydrous Et2O and 11.25 mL (120 mmol) of 3-bromothiphene. The flask was then cooled in an ice bath (0° C.). The Et2O solution of n-C18H37MgBr was slowly added to the flask containing the nickel catalyst and the 3-bromothiophene to prevent the generation of excessive heat and high concentrations of n-C18H37MgBr in the presence of the catalyst. The reaction mixture was allowed to stir overnight resulting in the formation of two layers. The top Et2O layer contained the product and the second small lower dark brown oily layer contained the Ni catalyst and the Mg salts. The primary side product of the reaction was the coupling product of two equivalents of n-C18H37MgBr to form C36H74, which was easily separated form the product since it had low solubility in Et2O. The product was purified via aqueous workup followed by filtration and removal of the Et2O by rotoevaporation to leave the impure low melting solid product. This solid was redissolved in a minimal amount of Et2O (˜30 mL) followed by addition of ˜250 mL of MeOH and placed into low temperature freezer (−80° C.) for recrystalization. The yield of this reaction is about 80-90%.

출처 및 근거