at ambient temperature by monitoring reactants and products with an electron impact mass spectrometer. At the low pressures used (0.7 and 1.0 mbar) the gas-phaseself-reaction is dominated by a ‘bimolecular’ H2-eliminating exit channel with a rate coefficient of k3b(300 K) = (1.3 ± 0.5) × 10−12 cm3 molecule−1 s−1 and leading to N2H2 + H2 or NNH2 + H2. Although the wall loss for NH2 radicals is relatively
NH 2分布图是在排气流反应器中于环境温度下通过用电子冲击质谱仪监测反应物和产物来测量的。在所用的低压(0.7和1.0 mbar)下,气相自反应主要由消除“双分子” H 2的出口通道控制,速率系数为k 3b(300 K)=(1.3±0.5)×10 -12 cm 3分子-1 s -1并产生N 2 H 2 + H 2或NNH 2 + H 2。尽管NH 2自由基的壁损耗相对较小(k瓦特≈6-14小号-1),对整体NH贡献2衰变是相对缓慢的气相反应,由于重要。异质反应产生N 2 H 4分子。
Kinetics of the cross reaction between amidogen and methyl radicals
作者:Jerzy T. Jodkowski、Emil Ratajczak、Kjell Fagerström、Anders Lund、Nigel D. Stothard、Robert Humpfer、Horst-Henning Grotheer
DOI:10.1016/0009-2614(95)00470-o
日期:1995.6
For the title reaction, the pressure dependent rate coefficients were studied at 298 K using two complementary experimental techniques. Pulse radiolysis combined with UV absorption was employed at pressures between 500 and 1000 mbar, while a fast-flow system with a quadrupole mass spectrometer (at low ionization energies) was applied at pressures in the range of 0.7–5.1 mbar. The fall-off curve was
Major mechanistic differences between the reactions of hydroxylamine with phosphate di- and tri-esters
作者:Michelle Medeiros、Eduardo H. Wanderlind、José R. Mora、Raphaell Moreira、Anthony J. Kirby、Faruk Nome
DOI:10.1039/c3ob40988k
日期:——
with H3N+–O− shows general base catalysis, which calculations show is involved in the breakdown of the phosphorane addition-intermediate of a two-step reaction. The reactivity of the diester anion DPP− is controlled by its more basic pyridyl N. Hydroxylamine reacts preferentially with the substrate zwitterion DPP± to displace first one then a second 2-pyridone, in concerted SN2(P) reactions, forming
羟胺最有可能通过其氨氧化物互变异构体作为氧亲核试剂与2-羟基吡啶的磷酸二酯和三酯发生反应。但是反应却截然不同。与三酯TPP的两步反应产物被溶液中存在的NH 2 OH捕集以生成二酰亚胺,这是由其预期的歧化和捕集产物确定的。用H反应3 Ñ + -O -节目一般碱催化,其中的计算显示涉及正膦加成中间两步反应的的击穿。二酯阴离子DPP的反应活性-由其更碱性的吡啶基N所控制。羟胺优先与底物两性离子DPP ±反应,在先导S N 2(P)反应中取代第一个,然后置换第二个2-吡啶酮,形成O-磷酸化的产物,该产物易于水解为无机盐磷酸盐。所建议的机制已得到广泛的理论计算的测试和支持。
Determination of the Rate Constants for the Radical−Radical Reactions NH<sub>2</sub>(X̃<sup>2</sup>B<sub>1</sub>) + NH(X<sup>3</sup>Σ<sup>−</sup>) and NH<sub>2</sub>(X̃<sup>2</sup>B<sub>1</sub>) + H(<sup>2</sup>S) at 293 K
作者:Mi-Kyung Bahng、R. Glen Macdonald
DOI:10.1021/jp809643u
日期:2009.3.19
constant for the reactionsNH2(X̃2B1) + NH(X3Σ−) and NH2(X̃2B1) + H(2S) were measured over a pressure range from 2 to 10 Torr in CF4, or Ar gases at 293 ± 2 K. The radicals were produced by the 193 nm photolysis of NH3 dilute in the carrier gas. Both radicals were monitored simultaneously following the photolysis laser pulse using high-resolution time-resolved absorption spectroscopy. The NH2 radical was
用于反应的速率常数NH 2(X 2乙1)+ NH(X 3 Σ - )和NH 2(X 2乙1)+ H(2 S),测定在压力范围从2到10托在CF 4,或293±2 K的Ar气。自由基是通过载气中NH 3稀溶液的193 nm光解产生的。使用高分辨率时间分辨吸收光谱仪,在光解激光脉冲之后,同时监测两个自由基。使用1 2 21 ← 1 3监控NH 2自由基(0,7,0)× 2 A 1 ←(0,0,0)X̃ 2 B 1振动带在675 nm附近的31旋转跃迁,并且使用1 R 3(4)旋转跃迁监测NH自由基在3084 nm附近的1-0振动跃迁上。使用NH 2和NH时间浓度分布图的模型模拟来分析数据。NH 2 + NH和NH 2 + H反应的速率常数为(9.6±3.2)×10 -11和(7.7±14)×10 -15 cm 3分子-1 s -1,其中不确定性包括系统误差和随机误差的估计。测量结果与稀释剂CF
Process to produce prostratin and structural or functional analogs thereof
申请人:The Board of Trustees of the Leland Stanford Junior University
公开号:US08067632B2
公开(公告)日:2011-11-29
This invention concerns a process to convert a hydroxyl group (bold in R3C—OH) in a tigliane-type compound to a hydrogen (bold in R3C—H) to obtain deoxytigliane-type compounds or structural or functional analogs thereof. The process has wide application particularly to produce specific biologically active compounds in quantity for use as pharmaceuticals. In particular the process can be used to convert phorbol to a 12-deoxytigliane (prostrating which is a therapeutic lead for the treatment of AIDS. New compositions of matter are also disclosed.