| 摘要: | 本研究以Tetraphenyl-N-confused porphyrin (HCTPPH2) 為配位基，與VO(acac)2 反應獲得VO(HCTPP)，並在不同的條件下進一步反應，成功合成出另外三種釩氧碳氮異位紫質(Oxovanadium N-confused porphyrin) 衍生錯合物，分別是VO(HCTPPO)、VO(HCTPPOMe) 以及VO(HCTPPOEt)。經由順磁1H NMR、UV-Vis 以及 ESI-Mass 等光譜及質譜鑑定，我們確定此些錯合物結構。並探討了此些釩氧碳氮異位紫質衍生錯合物之間轉換的反應條件及氧原子進行氧氣活化崁入碳釩化學鍵的可能反應機制。在催化反應研究部分，我們選擇cyclohexene 為反應物，分別以VO(HCTPP)、VO(HCTPPO)、VO(HCTPPOMe) 三種錯合物為催化劑，在30% H2O2 或 mCPBA 氧化劑為氧原子供給者下，進行氧原子轉移反應，並以標準物確定主要追蹤產物為cyclohexene epoxide、2-cyclohexen-1-ol、2-cyclohexen-1-one 和 cyclohexane-1,2-diol。透過檢量線計算個別產率，並以主要追蹤產物之產率加總計算轉化率。研究中，觀測到沒有任何氧化劑和催化劑的控制組，無任何產物生成。另外，只有氧化劑沒有催化劑的控制組，其產物生成量，在30% H2O2 作為氧化劑中為零，但是，在mCPBA 中cyclohexene epoxide 為主產物。在加入本研究所合成之釩紫質金屬催化劑後，在產物選擇性上有明顯改變，在30% H2O2 為氧化劑的催化實驗，其產物主要以2-cyclohexen-1-one 為主，而以 mCPBA 作為氧化劑的催化實驗，有別於沒有加入任何釩紫質金屬催化劑的以cyclohexene epoxide 為主要產物，其產物平均分布在cyclohexene epoxide 和 cyclohexane-1,2-diol 兩者，顯著改變產物之選擇性。根據這些結果，我們也以文獻結果作為輔證，探討可能的催化反應路徑及反應機制。;In this study, we utilized tetraphenyl-N-confused porphyrin (HCTPPH2) as a ligand to react with VO(acac)2, resulting in the formation of VO(HCTPP). Subsequently, through further reactions conducted under various conditions, we successfully synthesized three derivatives of oxovanadium N-confused porphyrin: VO(HCTPPO), VO(CTPPOMe), and VO(CTPPOEt). The structures of these complexes were confirmed through spectroscopic and mass spectrometry analyses, including paramagnetic 1H NMR, UV-Vis, and ESI-Mass. Our study also aimed to investigate the interconversion among these oxovanadium N-confused porphyrin derivatives and explore the potential reaction mechanism involving oxygen activation and carbon-vanadium bond insertion.
For the catalytic reaction investigations, cyclohexene was chosen as the substrate, and the catalysts employed were VO(HCTPP), VO(HCTPPO), and VO(HCTPPOMe). Oxygen atom transfer reactions were carried out using either 30% H2O2 or mCPBA as the oxygen atom donors. The primary products, namely cyclohexene epoxide, 2- cyclohexen-1-ol, 2-cyclohexen-1-one, and cyclohexane-1,2-diol, were identified by comparing their retention times with those of standard samples. The conversion percentage to each product was calculated based on the obtained product amounts using individual calibration curves. The total conversion yields were determined from the sum of the yields of the primary products. In the control experiments conducted without any oxidants or catalysts, no product formation was observed. Additionally, in the control groups with only oxidants but no catalysts, no product formation occurred when 30% H2O2 was used as the oxygen source. However, cyclohexene epoxide was identified as the main product when mCPBA was employed. Upon introducing the synthesized vanadium porphyrin metal catalysts, significant changes in product selectivity were observed. In catalytic experiments using 30% H2O2 as the oxidant, 2- cyclohexen-1-one became the predominant product. On the other hand, when mCPBA was used as the oxidant, the products were distributed between cyclohexene epoxide and cyclohexane-1,2-diol, indicating a substantial alteration in product selectivity. Based on these results and supported by information from the literature, we explored possible catalytic reaction pathways and mechanisms. |
