Study On The Isomerization Of Phosphono-Containing Trans-1,2-Difluoro-1-Alkenes

• Main Authors: Liang, Shihu, 梁世虎
• Other Authors: Tsai, Houjen
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/27704897645237645216

碩士 === 國防大學中正理工學院 === 應用化學碩士班 === 99 === Chlorotrifluoroethylene (F2C=CFCl) undergoes the dehalogen reaction with n-butyllithium (n-BuLi) at -78 oC to give the intermediate substance, [F2C=CF]-Li+. Silylation of [F2C=CF]-Li+ with chlorodimethylphenylsilane, chlorotrimethylsilane and chlorotriethylsilane affords dimethylphenylsilyltrifluoroethylene (F2C=CFSi- Me2Ph), trimethylsilyltrifluoroethylene (F2C=CFSiMe3) and triethylsilyltrifluoro- ethylene (F2C=CFSiEt3) in good yields respectively. Lithium aluminum hydride (LiAlH4), a reducing reagent, undergoes the addition-elimination reaction with dimethylphenylsilyltrifluoroethylene and trimethylsilyltrifluoroethylene to give trans-1,2-difluoro-1-phenyldimethylsilylethylene (HFC=CFSiMe2Ph) and trans-1,2- difluoro-1-trimethylsilylethylene (HFC=CFSiMe3). Deprotonation of trans-HFC=C- FSiMe2Ph with n-butyllithium forms the lithium salt, subsequent acylation with chlorodiphenylphosphine, diethyl chlorophosphite, bis(diethylamino)chlorophos- phine and dicyclohexylchlorophosphine gave phosphorus-containing trans-1,2- difluoro-1-dimethylphenylethylene (trans-R2PCF=CFSiMe2Ph, R = Ph, EtO, Et2N, cyc-C6H11) in good 19F NMR yields respectively. Under no isolation condition, directly oxided of trans-R2PCF=CFSiMe2Ph via 30 % hydrogen peroxide forms trans-R2P(O)CF=CFSiMe2Ph (R = Ph, EtO, Et2N, cyc-C6H11). The phosphono- containing trans-1,2-difluoro-1-silylethylene can be used as a good synthon in phosphorus-fluorine organic synthetic. Using dimethyl sulfoxide as solvent, a series of phosphono-containing trans-1,2-difluoro-1-alkenes (trans-R2P(O)CF=CFH, R = Ph, EtO, Et2N, cyc-C6H11) are prepared by potassium fluoride and water with trans-R2P(O)CF=CFSiMe2Ph. Photochemistry isomerization of trans-R2P(O)CF=CFH was carried out with catalytic amounts of diphenyl disulfide (Ph2S2) photosensitizer. Trans-R2P(O)- CF=CFH were irradiated by ultraviolet light (254 nm). After 72 hours, the ratio of cis- and trans-R2P(O)CF=CFH (R = Ph, EtO, Et2N, cyc-C6H11) is 84/16, 100/0, 96/4 and 51/49 in 19F NMR respectively. High ratio of cis isomer are observed for each compound.