CRITICAL EXAMINATION CONCERNING THE MECHANISTIC POSTULATES IN SOLVOLYTIC DISPLACEMENT REACTIONS

溶剂分解置换反应机理假设的批判性检验

• 批准号: 62470024
• 负责人: TSUNO Yuho
• 金额: $ 4.1万
• 依托单位: Okazaki National Research Institutes (1989)Kyushu University (1987-1988)
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1987
• 资助国家: 日本
• 起止时间: 1987 至 1989
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-62470024/
• 关键词: Solvolysis Mechanism; Ion Pair Mechanism; ^<18>O Isotope Shift; Scrambling; Return Process; Oー18スクランブリング; 同離体シフト

Quantitative analysis of the return process from ionic intermediates to the starting material in solvolysis plays a decisive role in the investigation of its reaction mechanism.The splitting, in the ^<13>C NMR signals of alkyl sulfonate esters, induced by isotopic oxygen substitution ^<16>O/^<18>O, was utilized to determine quantitatively the extent of ^<18>O scrambling within three oxygens in the sulfonate moiety. Oxygen exchange process (return process) as well as overall solvolysis process was successfully followed by ^<13>C NMR spectroscopy using a small amount of doubly labeled starting tosylate in a sealed NMR tube. In the acetolysis of neophyl tosylate, no ^<18>O-scrambling at the alkoxy oxygen of the starting tosylate was detected at all for whole range of reaction. The acetolysis of 2-(p-OMe-phenyl)ethyl tosyate gave the rearranged tosylates with complete randomization of the three oxygens. The ace- tolyses of 2-phenylpropyl and 2-phenylethyl tosylates also gave the rearranged … More tosylates of two signals, accompanying the incomplete oxygen equilibration. The different scrambling behaviors for substituted phenylethyl tosylates, may be attributable to the nature of the ion-pairs. In the acetolysis of 2-phenylethyl tosylate, parallel runs of (1-^*C)-OTs^* and (2-^*C)-OTs^* indicated the equivalence of two methylene carbons for ^<18>O-incorporation from sulfonyl oxygens in the return process. This provides strong evidence that the ^<18>O scrambling occurs only after the formation of symmetrical phenonium-ion species. In the acetolysis of benzyl tosylate, ^<18>O-scrambling was detected, being inconsistent with S_N2 mechanism.The acetolysis of 2-adamantyl tosylate referred to a typical k_c substrate also showed the occurrence of ion-pair return, suggesting the necessity of re-examination of solvolysis theories. It is apparent that the ^<13>C NMR method superior to the mass spectroscopic method can generally be applicable to the investigation of the return process in solvolysis. Less

溶剂解中离子中间体返回到起始原料的过程的定量分析在其反应机理的研究中起着决定性的作用。利用同位素氧取代^<16>O/^<18>O引起的烷基磺酸酯的^13C NMR信号中的分裂，可定量测定三个时间内^18O扰乱的程度。 磺酸盐部分中的氧。氧交换过程(返回过程)以及整个溶剂分解过程成功地随后进行13 C NMR光谱，在密封NMR管中使用少量双标记的起始甲苯磺酸盐。在甲苯磺酸新叶酯的乙酰解中，在整个反应范围内根本没有检测到起始甲苯磺酸酯的烷氧基氧上的18 O-扰乱。甲苯磺酸 2-(对-OMe-苯基)乙酯的乙酰解得到重排的甲苯磺酸酯，其中三个氧完全随机化。 2-苯基丙基和2-苯基乙基甲苯磺酸酯的乙酰解也产生了两个信号的重排甲苯磺酸酯，伴随着不完全的氧平衡。取代的甲苯磺酸苯乙酯的不同扰乱行为可能归因于离子对的性质。在甲苯磺酸2-苯乙酯的乙酰解中，(1-^*C)-OTs^*和(2-^*C)-OTs^*的平行运行表明两个亚甲基碳在返回过程中从磺酰氧引入^ 18 O-并入是等价的。这提供了强有力的证据表明^ 18 O扰乱仅在对称苯鎓离子物质形成之后发生。在甲苯磺酸苄酯的乙酰解中，检测到了^ 18 O-扰乱，与S_N2机制不一致。针对典型的k_c底物的2-金刚烷基甲苯磺酸酯的乙酰解也显示出离子对返回的发生，这表明有必要重新审视溶剂分解理论。显然，优于质谱方法的 13 C NMR方法通常可适用于溶剂分解中的返回过程的研究。较少的

项目成果

M.Fujio,F.Sanematsu,Y.Tsuno,Y.Takai,and M.Sawada: "Non-destructive Detection of Ion-pair Return in Acetolysis of ^<13>C and ^<18>O Doubly Labeled 2-Arylalkyl Tosylates.Quantitative ^<13>C-NMR Spectrometry by Using ^<18>O Isotope Effect" Nippon Kagaku Kais

M.Fujio、F.Sanematsu、Y.Tsuno、Y.Takai 和 M.Sawada：“^<13>C 和 ^<18>O 双标记 2-芳烷基乙酰解中离子对返回的无损检测

N. Shimizu, F. Shibata, and Y. Tsuno: "Synthesis of (1-Halo-1-alkenyl)-trimethylsilanes via gem-Trimethylsilylation of Vinyl Halides" Bull. Chem. Soc. Jpn.60. 777-778 (1987)

N. Shimizu、F. Shibata 和 Y. Tsuno：“通过乙烯基卤化物的宝石三甲基硅烷化合成 (1-卤代-1-烯基)-三甲基硅烷”Bull。

M. Fujio, F. Sanematsu, Y. Tsuno, M, Sawada, and Y. Takai: "Study of Ion-Pair Mechanism using Oxygen-18 Scrambling" Tetrahedron Lett.29. 93-96 (1988)

M. Fujio、F. Sanematsu、Y. Tsuno、M、Sawada 和 Y. Takai：“利用 Oxygen-18 扰码研究离子对机制”Tetrahedron Lett.29。

S.Imazu,N.Shimizu,and Y.Tsuno: "Autooxidation of Aromatic Ketones via Trimethylsilyl Enol Ethers" Mem.Fac.Sci.,Kyushu Univ.,Ser.C. 16(2). 189-192 (1988)

S.Imazu、N.Shimizu 和 Y.Tsuno：“通过三甲基硅基烯醇醚进行芳香酮的自动氧化”Mem.Fac.Sci.，九州大学，Ser.C。

M.Fujio,M.Goto,T.Suzuki, M.Mishima,and Y.Tsuno: "Substituent Effects.XXI.Solvioysis of Benzyl Tosylates" Bull.Chem.Soc.Jpn.,in press.

M.Fujio、M.Goto、T.Suzuki、M.Mishima 和 Y.Tsuno：“取代基效应。XXI.甲苯磺酸苄酯的溶剂化”Bull.Chem.Soc.Jpn.，出版中。