The regio- and stereospecificity of bimolecular phenoxy radical coupling reactions, of especial importance in lignin and lignan biosynthesis, are clearly controlled in some manner in vivo; yet in vitro coupling by oxidases, such as laccases, only produce racemic products. In other words, laccases, peroxidases, and comparable oxidases are unable to control regio- or stereospecificity by themselv...

The lifetimes of pre-reactive complexes, although implicitly part the equations used to model many gas-phase bimolecular reactions, have seldom been included in quantitative calculations rate coefficients. Here, we demonstrate application empirical molecular dynamics simulations collisions between peroxy radicals association lifetimes. With exception methyl peroxy–acetyl system, measurements ba...

This study reports evidence for catalytic deoxygenation of alkanols, alkanals, and alkanediols on dispersed Cu clusters with minimal use of external H(2) and with the concurrent formation of new C-C and C-O bonds. These catalysts selectively remove O-atoms from these oxygenates as CO or CO(2) through decarbonylation or decarboxylation routes, respectively, that use C-atoms present within reacta...

We study the kinetics of bimolecular, catalytically-activated reactions (CARs) in d-dimensions. The elementary reaction act between reactants takes place only when these meet in the vicinity of a catalytic site; such sites are assumed to be immobile and randomly distributed in space. For CARs we develop a kinetic formalism, based on Collins-Kimball-type ideas; within this formalism we obtain ex...

A bimolecular chemical reaction in solution constitutes a many-body problem. Even in the pseudounimolecular limit, when one reactant ~say, B! is in large excess over the other ~say, A! there are many B molecules which compete over binding to A. Yet, such effects are generally thought to be of little practical relevance. This impression possibly stems from the intensive study of irreversible dif...

The second reaction has been very carefully investigated, and it was shown that an equilibrium occurs [Lehmann, 1935; 1936]. The equilibrium point depends on pH. It was further found that the reaction is not trimolecular. It can be split up into two bimolecular reactions in which adenosinediphosphate (a substance discovered by Lohmann [1935] in crab muscle) figures in vertebrate muscle also, as...

For the hydrogen transfer of phenalene, a bimolecular ene-like mechanism is proposed, which is preferable over the hypothesized unimolecular rearrangement in the literature. Unique SOMO-SOMO pi-bonding of phenalenyl reduces the barriers of pericyclic reactions significantly. Pi-bonding between radicals is being recognized as a novel type of bonding interaction. This paper adds to the use of thi...

Molecular programming aims to systematically engineer molecular and chemical systems of autonomous function and ever-increasing complexity. A key goal is to develop embedded control circuitry within a chemical system to direct molecular events. Here we show that systems of DNA molecules can be constructed that closely approximate the dynamic behavior of arbitrary systems of coupled chemical rea...

Base-catalyzed urea–formaldehyde condensation reactions were investigated by using a quantum chemistry method. It was found that monomethylolurea or N,N’-dimethylolurea can produce the methyleneurea intermediate (–HN–CO–N=CH2) with the catalysis of base. The E1cb (unimolecular elimination of conjugate base) mechanism was identified for the formation of such an intermediate. The potential energy...