从产物分布的观点出发,已经研究了二锂联苯基(Li 2 C 12 H 10)与烷基氟化物的反应。两种主要的反应途径,亲核取代(S N 2)和电子转移(ET),可以竞争产生相同的烷基化产物,即所谓的S N 2–ET二分法。S N 2似乎是与伯烷基氟化物(n -RF)相互作用的主要机理。烷基化反应的收率很高,所得的烷基化二氢联苯阴离子(n -RC 12 H 10 Li)可以用第二种常规亲电试剂(E +),得到了合成上令人感兴趣的脱芳香化联苯衍生物(n -RC 12 H 10 E)。随着我们向仲(s -RF)和叔烷基氟化物(t -RF)的转移,反应产生了更多的ET产物,在这种情况下,该机理似乎主要由ET主导。在这种情况下,烷基化通过自由基偶合仍然可行,从而获得合成吨-RC 12 ħ 10 E,虽然在较低的产率。对这个S N的合理解释基于将5-己烯基氟化物和1,1-二甲基-5-己烯基氟化物用作与Li
Cocatalysis by tetravalent tin compounds in phase-transfer catalyzed fluorination of alkyl halides and sulfonates
作者:Mieczysław Mąkosza、Robert Bujok
DOI:10.1016/s0040-4039(02)00376-3
日期:2002.4
Phase-transfer catalyzed fluorination of alkyl halides or sulfonates is co-catalyzed efficiently by triorganotin halides. The cocatalytic action is due to continuous formation of lipophilic hypervalent triorganodifluorostannate anions, which act as fluorinating agents in the organic phase.
The nucleophilic fluorination of alkyl iodides, bromides and tosylates and of α-bromo- or α-chloroketones is smoothly effected by tetrabutylammonium hydrogen difluoride in the presence of pyridine, in dioxane or THF, with good or satisfying substitution-to-elimination ratio.
fluorobenzenes, proceed with good conversions and moderate yields. In the latter reaction, HF generation, diazotization and fluoro de-diazonization can all be carried out in one pot. Reactions can be performed at ambient temperatures and pressures. HF generation using NaF or KF as fluoride sources is less efficient due to formation of stable bifluorides. Lipophilic quaternary ammonium salts such as tetra-n-octylammonium
该原位生成的无水HF的由固体的CaF的反应2用H 2 SO 4有人提出,在含有底物的有机相存在下,作为其他氟化方法的一种简单安全的替代方法。使用这种方法,将HF加到烯烃中以生产氟代烷烃,用F原子取代羟基和卤化物官能团,以及将苯胺转化为氟苯,均能获得良好的转化率和中等的收率。在后一反应中,HF的产生,重氮化和氟脱重氮均可以在一个罐中进行。反应可以在环境温度和压力下进行。由于形成稳定的双氟化物,使用NaF或KF作为氟化物源的HF生成效率较低。亲脂性季铵盐,例如四正-辛基溴化铵可用于增强HF在有机相中的萃取。讨论了溶剂性质和试剂比例的影响。
POTASSIUM FLUORIDE DISPERSION SOLUTION, AND PROCESS FOR PRODUCTION OF FLUORINATED ORGANIC COMPOUND USING THE SAME
申请人:Hagiya Koji
公开号:US20090099387A1
公开(公告)日:2009-04-16
A potassium fluoride dispersion essentially consisting of potassium fluoride and an aprotic organic solvent having a boiling point higher than that of methanol, which is obtainable by mixing a mixture containing potassium fluoride and 5 to 50 parts by weight of methanol per 1 part by weight of potassium fluoride with the aprotic organic solvent followed by concentrating the obtained mixture, and a process for producing a fluorine-containing organic compound comprising contacting an organic compound having at least one group capable of being substituted nucleophilically with a fluorine atom with the potassium fluoride dispersion.
A useful conversion of alcohols to alkyl fluorides
作者:David A Flosser、Roy A Olofson
DOI:10.1016/s0040-4039(02)00738-4
日期:2002.6
A usefulconversion of alcohols to alkyl fluorides via their fluoroformates is introduced. The fluoroformates are obtained in nearly quantitative yield from the alcohols by treatment with COF2 (generated in situ from bis(trichloromethyl) carbonate) in ether with KF as an added acid scavenger. The neat fluoroformates are cleaved to the fluorides by heating at 120–125°C using hexabutylguanidinium fluoride