Computational study radicals

The study of the peak temperature sensitivity to the reactor operating parameters and the construction of sensitivity boundary curves for stable reactor operation were previously reported ( l). This paper presents a computer study on conceptual relationships between the conversion-product properties and the reactor operating parameters in a plug flow tubular reactor of free radical polymerization. In particular, a contour map of conversion-molecular weight relationships in a reactor of fixed size is presented and the sensitivity of its relationship to the choice of initiator system, solvent system and heat transfer system are discussed. 

In addition, another computational study in the frame of DFT, using the hybrid functional MPW1K,53 had suggested that o-QM may be an intermediate in the reaction of the peroxy radical (HO2") with the benzyl radical at the ortho-position (Scheme 2.16),54 which should be significant in atmospheric processes and low-temperature combustion systems (T < 1500 K). 

Finally, a preliminary computational study on the dimerization of 1,3,2-diaza-phospholenyl radicals suggested that the easy formation of these species might be facilitated by a very low dissociation energy of the corresponding dimer [46],... 

Computational study at 6-31 lg level of theory of l-bora-4-adamantyl radicals showed that ry -isomer 14a is more stable than anti-one 14b by 0.23 kcal mol-1 (Figure 3). These radicals are proposed <1999CRV1377> to be the intermediates in reduction of 4- A-chloro-l-boraadamantane with -Bu3SnD <1996JOC9588>. 

A computational study was concerned with the effect of solvation on the radical ion involved in CDP photolyase enzyme-catalysed reversion of thymine and uracil cyclobutane dimers stimulated by visible light <06T6490>. 

Substituents at the allene in general and methyl groups in particular favor /3-addition of radicals, which leads to the formation of allylic and therefore stabilized intermediates. Results from computational studies predict that CH3 addition to Cp of... 

A recent study has indicated that the skeletal rearrangement step in the B12-catalysed isomerization of methylmalonyl-CoA to succinyl-CoA occurs not by a radical pathway but by an anionic or organocobalt pathway. A computational study of the isomerization of allyl alcohol into homoallyl alcohol by lithium amide has pointed to a process proceeding via a transition state in which the proton is half transferred between carbon and nitrogen in a hetero-dimer. l,l-Dilithio-2,2-diphenylethene... 

Partial premixing has been proposed as a means of NOj, reduction in gas turbine engines by Jayavant Gore at Purdue University. An experimental and computational study was conducted to observe NO behavior under the circumstances of moderate stretch rate, opposed-flow, partially premixed flames. The results show that the minimum NO emissions at an optimal level of partial premixing result as a consequence of decrease in CH radical concentrations. Partial premixing appears to be a possible practical immediate solution for NO remediation in gas turbines. 

In marked contrast to the generally accepted mechanism, the involvement of a radical pair produced by an alkene-induced 0—0 bond homolysis was suggested by Minisci and coworkers . In a combined experimental and theoretical study Curci, Houk and coworkers sought to differentiate between a radical pathway and the commonly accepted concerted mechanism. Both product and kinetic smdies tended to exclude a radical pathway. Computational studies at the B3LYP/6-31G level on the epoxidation of isobutylene with DMDO predicted an activation energy = 15.3 kcalmor ) significantly lower... 

Synopsis of Ochiai, Tomita, and Endo (2001) Investigation on Radical Polymerization Behavior of 4-Substituted Aromatic Enynes. Experimental, ESR, and Computational Studies . 

Theoretical studies have indicated that m-bcnzync is monocyclic with a C(l)-C(3) distance of 2.0 A whereas in tetrafluoro-w-benzyne the increased eclipsing strain between fluorine atoms stabilizes the bicyclo[3.1.0]hexatriene form with a C(l)-C(3) distance of 1.75 A.56 Computational studies coupled with gas-phase experimental studies show that appropriate substituents can be used to tune the reactivity of 1,3-arynes. Thus the presence of NH+ at C(5) makes (13) mildly carbocationic whereas the addition of OH at C(4) in (14) gives a highly reactive (bi)radical.57... 

N.R. Jena et al., Mechanisms of formation of 8-oxoguanine due to reactions of one and two OH- radicals and the H202 molecule with guanine A quantum computational study. J. Phys. Chem. B 109, 14205-14218 (2005)... 

Computational studies by Rablen have suggested that ligands with 7i-donor abilities are much more efficient in the reduction of the B-H BDE [8]. On the basis of this finding, it has recently been demonstrated that complexes of NHCs and borane (NHC boranes) constitute a very interesting new class of radical hydrogen atom donors. Two of the first examples, 1 and 2, together with their calculated BDEs, are shown in Scheme 1. 

Bottoni also reported the results of computational studies into the abstraction of hydrogen atom by silyl and trichlorosilyl radicals from chloromethane, dichloromethane and chloroform (equation 15)42, and concluded that hydrogen abstraction does not effectively compete with halogen abstraction in the systems investigated. B3LYP/6-31G calculated energy barriers for these reactions fall in the approximate range of 46-72 kJmol-1. 

As shown by Clark [38] in a comprehensive computational study of (HnX XHn)+ radical cations (X= Li to C, Na to Si), one-electron bonds are already rather well described by simple Hartree-Fock theory. This is because the active system contains a single electron, so that the breathing orbital effect is ineffective in the active subspace, where each orbital is either empty or singly occupied as illustrated in 32, 33 for the OC bond. 

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