已经测量了磷酸二酯 3,3-二甲基丁基对硝基苯基磷酸酯在酸和碱水解、β-环糊精裂解和蛇毒磷酸二酯酶裂解条件下的磷酰基转移反应的次级 18 O 和 15 N 同位素效应。同位素标记和其他实验表明,这些反应通过 SN 2(P) 机制进行。次级 18 O 同位素效应测量在这些 SN 2 反应中与中心磷酰基中的非桥氧原子结合的过渡态的变化。15 N 同位素效应测量到离去基团对硝基苯酚的过渡态键断裂。
Oxyfunctionalization with Cp*IrIII(NHC)(Me)L Complexes
摘要:
A series of monomethyl Cp*Ir-III complexes were synthesized and studied for the formation of methanol in water. Methanol yields of 75(4)% in the presence of O-2 were obtained. From isotope labeling studies, it was determined that O-2 is the source of the oxygen atom in the product. From kinetic studies, oxyfunctionalization appears to proceed by dissociation of an L-type ligand followed by O-2 binding and insertion.
A Kinetic Isotope Effect Study on the Hydrolysis Reactions of Methyl Xylopyranosides and Methyl 5-Thioxylopyranosides: Oxygen versus Sulfur Stabilization of Carbenium Ions
作者:Deepani Indurugalla、Andrew J. Bennet
DOI:10.1021/ja011232g
日期:2001.11.1
(J. Am. Chem. Soc. 1986, 108, 7287-7294) KIEs for the acid-catalyzed hydrolysis of methyl alpha- and beta-glucopyranosides, it is possible to conclude that at the transition state for xylopyranoside hydrolysis resonance stabilization of the developing carbenium ion by the ring oxygen atom is coupled to exocyclic C-O bondcleavage, and the corresponding methyl glucopyranosides hydrolyze via transition
Formation of complex organic molecules in methanol and methanol–carbon monoxide ices exposed to ionizing radiation – a combined FTIR and reflectron time-of-flight mass spectrometry study
作者:Surajit Maity、Ralf I. Kaiser、Brant M. Jones
DOI:10.1039/c4cp04149f
日期:——
photoionization at 10.49 eV. Infrared spectroscopic analysis of the processed ice systems resulted in the identification of simple molecules including the hydroxymethyl radical (CH2OH), formyl radical (HCO), methane (CH4), formaldehyde (H2CO), carbon dioxide (CO2), ethylene glycol (HOCH2CH2OH), glycolaldehyde (HOCH2CHO), methylformate (HCOOCH3), and ketene (H2CCO). In addition, ReTOF mass spectrometry of
An unusual and novel reaction of alpha-alkoxyphosphonium salts, generated from O,O-acetals and Ph(3)P, with Grignard reagents under an O(2) atmosphere afforded alcohols in moderate to high yields. It was clarified by isotopic labelling experiments that the reaction proceeded via a novel radical pathway.
in particular methanol. However, due to the incomplete transformation of intermediates or the overoxidation of products, a good selectivity of methanol is hard to achieve. Here, we present a highly selective transformation of methane to methanol using gold modified zinc oxide as a photocatalyst under full light spectrum irradiation at atmospheric temperature. The selectivity of methanol can reach 99
光驱动的CH 4转化被认为是制造增值商品化学品(特别是甲醇)的有前途的绿色战略。然而,由于中间体的不完全转化或产物的过度氧化,难以实现良好的甲醇选择性。在这里,我们介绍了在大气温度下全光谱照射下,使用金改性的氧化锌作为光催化剂,将甲烷高度选择性地转化为甲醇的过程。甲醇的选择性可以达到99.1%,产率为1371μmolg -1。微调金纳米颗粒的负载量(0.75重量%)并输入适当的光能是提高选择性的关键因素。此外,与报道的光催化好氧CH相反在金修饰的氧化锌上进行4氧化时,我们发现氧气和水(而不是仅分子氧)都为形成甲醇提供了O源。通过18个O同位素测试( 18 O 2和H 2 18 O)验证了该结果,从而得出了不同的机理。
Methane Activation by Titanium Monoxide Molecules: A Matrix Isolation Infrared Spectroscopic and Theoretical Study
作者:Guanjun Wang、Yu Gong、Mohua Chen、Mingfei Zhou
DOI:10.1021/ja0604010
日期:2006.5.1
the methanemolecule. The complex rearranged to the CH3Ti(O)H titano-acetaldehyde molecule upon visible (lambda > 500 nm) irradiation. The titano-acetaldehyde molecule sustained further photochemical rearrangement to the CH2Ti(H)OH titano-vinyl alcohol molecule, which was characterized to be a simple carbene complex involving agostic bonding. The CH2Ti(H)OH molecule reacted with a second methane to