Hydrogen synchronous

The reaction proceeds by an Ei-mechanism. The /3-hydrogen and the carboxy-late are cleaved synchronously from the substrate molecule, while forming a new bond. This elimination reaction belongs to the class of -eliminations in the case of the ester pyrolysis, the substrate molecule passes through a six-membered cyclic transition state 4 ... 

M. Quack, U. Schmitt, and M. A. Suhm, FTIR spectroscopy of hydrogen fluoride clusters in synchronously pulsed supersonic jets Isotopic isolation, substitution and 3 D condensation. Chem. Phys. Lett. 269, 29 38 (1997). 

Transfer of hydrogen occurs exclusively in a syn manner and it has been concluded that the reduction of a multiple bond by diimide involves a synchronous transfer of a pair of hydrogens to a single face of the carbon-carbon double bond via a six-membered cyclic transition state to give a syn adduct (equation 22)77,81. 

Formation of 2//-azirines by thermal decomposition of vinyl azides has been shown to exhibit small entropy of activation and insensitivity to solvent polarity acyclic vinyl azides decompose more readily than analogous cyclic ones and it is advantageous to have a hydrogen atom cis to the azido group ( -are more reactive than Z-isomers). These results and the linear correlation found for ring-substiment effects on decomposition of a-styryl azides are consistent with a nonconcerted mechanism in which elimination of nitrogen and cyclization into a three-membered ring proceeds synchronously. 

Swem dimer, hydrogen bonding, 104, 105 Synchronous transition states, peracid alkene epoxidation, 50-8 syn selectivity, regioselective aUyUc... 

It was found that most synthetic processes that are employed to prepare the diimide reagent generate trans-diimide, but ds-diimide undergoes faster hydrogen atom transfer to a double bond than does the trans isomer. It follows that a fast trans-cis isomerization precedes reduction. The transfer of hydrogen atoms takes place in a synchronous process188 via the transition state 19 ... 

The E2 mechanism is so called because the process is bimolecular and in solution consists of an attack by a base on the 3-hydrogen atom with synchronous splitting of the substituent X in the form of an anion. In heterogeneous catalysis, the most important feature is the timing of the fission of the two bonds Ca—X and C —H in the E2 or E2-like mechanism, these bonds are broken simultaneously. Because this can be achieved only by the action of two different centres, a basic one and an acidic one with both present on the surface, the kinetic distinction of the mechanism loses its original sense under these circumstances. 

The spontaneous rearrangement of I has been the subject of a detailed kinetic study (6) which showed that a synchronous hydrogen exchange took place in a dimeric complex. 

One proposed technique is to aim an array of laser beams at a common point and drop solid pellets of hydrogen isotopes through the synchronous crossfire, as Figure 4.32 shows. The energy of the multiple beams should crush the pellets to... 

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