Kinetics of the reactions of laser-flash photolytically generated carbenium ions with alkyl and silyl enol ethers. Comparison with the reactivity toward alkenes, allylsilanes and alcohols
作者:Joerg Bartl、Steen Steenken、Herbert Mayr
DOI:10.1021/ja00020a038
日期:1991.9
corresponding alkyl-substituted ethylenes. The reactivities of structurally analogous alkyl and silylenolethers differ by less than 1 order of magnitude. In sharp contrast to the situation previously observed for the reactions of benzhydryl cations with alkenes, the nucleophilic reactivities of the enolethers correlate with their ionization potentials and not with the stabilities of the carbenium ions
二芳基碳鎓离子(二苯甲基阳离子)是在 20 OC 的乙腈溶液中通过 20-11 秒激光脉冲 (248 nm) 从二芳基甲基氯生成的。它们与 n 和 w 亲核试剂(阴离子、醇、水、烯烃、烯丙基硅烷、烷基和甲硅烷基烯醇醚)反应的二级速率常数是通过在可变亲核试剂浓度下监测 UV-vis 瞬变的衰减来确定的。由于碳鎓离子与溶剂乙腈和光杂解中产生的氯离子同时发生反应,因此只能通过这种方法研究反应性亲核试剂 (k2 > 106-107 L mol-' sI)。观察到的最大 k2 值为 -2 X 1Olo 与阴离子反应和 (2-4) X IO8, mol-' sI 与中性亲核试剂反应。烷氧基取代的乙烯的反应性比相应的烷基取代的乙烯高 300-1 倍。结构相似的烷基和甲硅烷基烯醇醚的反应性相差不到 1 个数量级。与之前观察到的二苯甲基阳离子与烯烃反应的情况形成鲜明对比的是,烯醇醚的亲核反应性与其电离电位相
Silica Chloride (SiO<sub>2</sub>-Cl), a New Heterogeneous Reagent, for the Selective and Efficient Conversion of Benzylic Alcohols to Their Corresponding Chlorides and Iodides
Abstract Structurally different benzylic alcohols were efficiently converted to their corresponding chlorides by silica chloride (SiO2-Cl) in CHCl3 at room temperature. Silica chloride is also able to convert benzylic alcohols to their iodides in the presence of NaI in a mixture of CH3CN/CHCl3 in excellent yields.
摘要 在室温下,在 CHCl3 中的氯化硅 (SiO2-Cl) 可以将结构不同的苄醇有效地转化为其相应的氯化物。在 NaI 存在下,在 CH3CN/CHCl3 混合物中,氯化硅也能够以极好的收率将苄醇转化为其碘化物。
New One-Pot Synthesis of Alkyl Nitrates from Alcohols
作者:Luis Castedo、Carlos F. Marcos、Mercedes Monteagudo、Gabriel Tojo
DOI:10.1080/00397919208019268
日期:1992.3
Abstract Treatment of alcohols with Ph3P-I2-invidazole followed by “in situ” reaction of the generated iodides with AgNO3 allows the mild conversion of alcohols into alkyl nitrates. Unlike previous procedures, this one requires no electrophilic nitrating conditions.
Synthesis of alkyl iodides/nitriles from carbonyl compounds using novel ruthenium tris(2,2,6,6-tetramethyl-3,5-heptanedionate) as catalyst
作者:Malhari D. Bhor、Anil G. Panda、Nitin S. Nandurkar、Bhalchandra M. Bhanage
DOI:10.1016/j.tetlet.2008.09.002
日期:2008.11
Aldehydes and ketones were hydrogenated to the corresponding alcohols, which were then transformed in situ into their respective iodides and nitriles in good yields. A structurally well-defined O-containing transition metal complex, Ru (TMHD)3, was found to be the active catalyst for hydrogenation, iodination and cyanation reactions. It has high affinity for the transformation of benzylic alcohols
Silicaphosphine (Silphos), [P(Cl)3−n(SiO2)n], as a new heterogeneous reagent is introduced. This reagent converts alcohols and thiols to their corresponding bromides and iodides in the presence of X2 (X=Br, I) in refluxing CH3CN in high to quantitative yields. Use of Silphos provides a highly practical method for the easy separation of the Silphos oxide byproduct by a simple filtration.