1H and13C NMR Detection of the Carbocations or Zwitterions from Rhodamine B Base, a Fluoran-Based Black Color Former, Trityl Benzoate, and Methoxy-Substituted Trityl Chlorides in the Presence of Alkali Metal or Alkaline Earth Metal Perchlorates in Acetonitrile Solution
Hydricities of BzNADH, C5H5Mo(PMe3)(CO)2H, and C5Me5Mo(PMe3)(CO)2H in Acetonitrile
摘要:
The thermodynamic hydride donor abilities of 1-benzyl-1,4-dihydronicotinamide (BzNADH, 59 +/- 2 kcal/mol), C5H5Mo(PMe3)(CO)(2)H (55 +/- 3 kcal/mol), and C5Me5Mo(PMe3)(CO)(2)H (58 +/- 2 kcal/mol) have been measured in acetonitrile by calorimetric and/or equilibrium methods. The hydride donor abilities of BzNADH and C5H5Mo(PMe3)(CO)2H differ by 13 and 24 kcal/mol, respectively, from those reported previously for these compounds in acetonitrile. These results require significant revisions of the hydricities reported for related NADH analogues and metal hydrides. These compounds are moderate hydride donors as compared to previously determined compounds.
Reactivities of triarylmethyl and diarylmethyl cations with azide ion investigated by laser flash photolysis. Diffusion-controlled reactions
作者:Robert A. McClelland、V. M. Kanagasabapathy、Narinder S. Banait、Steen Steenken
DOI:10.1021/ja00003a040
日期:1991.1
By use of the technique of laser flashphotolysis, rate constants k AZ and k S have been directly measured for the reactions at 20 o C in acetonitrile-water (AN-W) solutions of varying composition of 18 triarylmethyl and 10 diarylmethyl cations with azide and solvent. The cations have k S that depend on substituent and vary from ∼10 1 to ∼10 7 s −1 . For the more stable ions k AZ also varies, increasing
通过使用激光闪光光解技术,已经直接测量了在 20 o C 下在 18 个三芳基甲基和 10 个二芳基甲基阳离子与叠氮化物的不同组成的乙腈-水 (AN-W) 溶液中反应的速率常数 k AZ 和 k S和溶剂。阳离子具有取决于取代基的k S 并且从~10 1 到~10 7 s -1 变化。对于更稳定的离子,k AZ 也发生变化,随着给电子量的减少而增加,并且随着乙腈含量的增加而增加多达10 3 。然而,对于不太稳定的阳离子,速率常数与取代基无关
The oxidation of a dimeric N-benzyldihydronicotinamide with various oxidants such as quinones, triphenyl carbenium ions and a triplet exited tris(bipyridine) ruthenium(II) complex occurs via initial outer-sphere electron transfer followed by fast C–C bond cleavage and second electron transfer. The kinetic studies allow the determination of the oxidation potential of this compound.
二聚 N-苄基二氢烟酰胺与各种氧化剂(如醌、三苯基碳鎓离子和三重态三(联吡啶)钌 (II) 络合物的氧化)通过初始外球电子转移随后快速 C-C 键断裂和第二电子发生转移。动力学研究可以确定该化合物的氧化电位。
General acid catalysis of alcohol heterolysis
作者:Clifford A. Bunton、Faegh Davoudazedeh、William E. Watts
DOI:10.1021/ja00403a038
日期:1981.7
The conversion of diferrocenylphenylmethanol (5) into the carbocation is generalacid catalyzed in H/sub 2/O:CH/sub 3/CN, 1:1 w/w, and ..cap alpha.. = 0.88. The corresponding reaction of tropyl alcohol is also generalacid catalyzed, and ..cap alpha.. = 0.71 and 0.90 in water and H/sub 2/O:CH/sub 3/CN, 1:1 w/w, respectively. However, the hydrogen ion catalyzed reactions have inverse solvent kinetic
Reactivities of diarylmethyl and triarylmethyl cations with primary amines in aqueous acetonitrile solutions. The importance of amine hydration
作者:Robert A. McClelland、V. M. Kanagasabapathy、Narinder S. Banait、Steen Steenken
DOI:10.1021/ja00031a041
日期:1992.2
By use of the technique of laser flash photolysis, rate constants k(RNH 2 ) have been directly measured for the reactions of primary amines RCH 2 NH 2 (R=CH 3 CH 2 , CH 3 OCH 2 , NCCH 2 , CF 3 ) with diarylmethyl cations (D + ) in acetonitrile/water solutions
Concerning the Role of Supercritical Carbon Dioxide in S<sub>N</sub>
1 Reactions
作者:Yun X. Qiao、Nils Theyssen、Tobias Eifert、Marcel A. Liauw、Giancarlo Franciò、Karolin Schenk、Walter Leitner、Manfred T. Reetz
DOI:10.1002/chem.201604151
日期:2017.3.17
A series of SN1‐type reactions has been studied under various conditions to clarify the role of supercritical carbon dioxide (scCO2) as reaction medium for this kind of transformations. The application of scCO2 did not result in higher yields in any of the experiments in comparison to those under neat conditions or in the presence of other inert compressed gases. High‐pressure UV/Vis spectroscopic
已经在各种条件下研究了一系列S N 1型反应,以阐明超临界二氧化碳(scCO 2)作为这类转化反应介质的作用。与在纯条件下或在其他惰性压缩气体存在下进行的实验相比,使用scCO 2在任何实验中均未获得更高的产率。进行了高压UV / Vis光谱测量,以量化高S N 1活性烷基卤化物的碳阳离子形成程度与所用溶剂的关系。scCO 2中未检测到可测量的碳正离子浓度,就像在其他低极性溶剂中一样。综上所述,由于超临界流体的四极矩,这些结果不能通过增强的S N 1电离来支持先前要求的活化作用。