Dimethylaniline electron transfer

Wang 0, Akhremitchev B and Walker G 0 1997 Femtosecond infrared and visible spectroscopy of photoinduced intermolecular electron transfer dynamics and solvent-solute reaction geometries Coumarin 337 in dimethylaniline J. Rhys. Chem. A 101 2735-8... 

The mechanism proposed for the production of radicals from the N,N-dimethylaniline/BPO couple179,1 involves reaction of the aniline with BPO by a Sn-2 mechanism to produce an intermediate (44). This thermally decomposes to benzoyloxy radicals and an amine radical cation (46) both of which might, in principle, initiate polymerization (Scheme 3.29). Pryor and Hendrikson181 were able to distinguish this mechanism from a process involving single electron transfer through a study of the kinetic isotope effect. 

V,/V-dimethylaniline, especially when those strong donors are paired with the relatively electron-poor MES derivative of the bis(arene)iron(ll) acceptor. As such, the dark reactions arise via essentially the same multistep mechanism as that for charge-transfer de-ligation, the difference arising from an adiabatic electron transfer (10) as the initial step that is thermally allowed when the driving force -AGET is sufficient to surmount... 

This means that 4-nitrostilbene is a more effective electron acceptor than nitrobenzene. This theoretical conclusion is verified by experiments. The charge-transfer complexes formed by nitrobenzene or 4-nitrostilbene with Af,Af-dimethylaniline have stability constants of 0.085 L mol or 0.296 L mol respectively. Moreover, the formation of the charge-transfer complex between cis-4-nitrostilbene and A/,Af-dimethylaniline indeed results in cis-to-trans conversion (Dyusengaliev et al. 1995). This conversion proceeds slowly in the charge-transfer complex, but runs rapidly after one-electron transfer leading to the nitrostilbene anion-radical (Todres 1992). The cis trans conversion of ion-radicals will be considered in detail later, (see sections 3.2.5.1, 6.4, and 8.2.1). 

The inhibition of hydrocarbon oxidation by aromatic tertiary amines which contain no labile hydrogen, such as N,N-dimethylaniline and N,N,N, N -tetramethyl-p-phenylenediamine, has been assigned to an electron-transfer process. However, this seems rather unlikely as pyridine... 

The application34 of time-dependent diffusion theory to the quenching constant kCMTf for the perylene-dimethylaniline system in acetonitrile, which exhibits a pronounced dependence on quencher concentration, provides a value of 6 A for the quenching encounter diameter as the adjustable parameter which considerably exceeds that of 3 A computed for the same system in benzene. This accords with the conclusions of Leonhardt and Weller35 that electron transfer may occur with direct contact of donor and acceptor in polar media (Section V.E). 

With deuterium-labeled dimethylaniline as the excited electron donor, primary electron transfer to aryl halides is followed by proton transfer yielding reduced aryl nitro compounds and functionalized dimethylanilines (193). 

If electron transfer generates a charged ion which is hydrophilic and bears the same charge as the micelle, its expulsion from the micellar cage will reduce the rate of back electron transfer. In a cationic micelle, for example, electron transfer from dimethylaniline to excited Ru(bpy ), +> eq. 86,... 

The fluorescence of anthracene in benzene is efficiently quenched by N,N-dimethylaniline and a strong exciplex emission appears in a longer wavelength than the emission of anthracene [382-384], However, the addition product was not obtained at all, except the (4 + 4) anthracene dimer (Scheme 114). In contrast, the addition product and reductive dimerization product of dimethylaniline to the anthracene ring are produced via photoinduced electron transfer, which was first reported by Pac and Davidson [385-387], In the case of V-mcthylaniline, some addition products are obtained both in nonpolar and polar solvents [386-389],... 

Considering the large variety of fullerene adducts, only a few investigations on photochemical processes of fullerene adducts have been reported. These studies deal mainly with reductive processes due to the easy reduction of fullerenes and its adducts. Studies on electron transfer processes of several pyrrolidino fullerenes (Fig. 20) with donors such as dimethylaniline (DMA) or tetrakis(dimethy-lamino)ethylene (TDAE) show that the electron transfer rate constants decrease compared to that of C6o (3.5 X 109 M 1 s 1 for C6o, 0.5 X 109 M 1 s 1 for the derivatives (Table 6, Fig. 21) [179], This can be interpreted in terms of decreasing u-conjugation of the C60 moiety, which causes an increase in LUMO energy level and a decrease in the lowest triplet energy. Therefore, the substituents influ-... 

A relative of 12 has been prepared by Sanders, van der Plas, and coworkers [64], Triad 13 features an N,A-dimethylaniline-type donor and an anthraquinone acceptor. These moieties are linked to the ortho positions of the porphyrin aryl groups, and this leads to a folded conformation for the molecule, as determined from NMR studies. Both the free base and zinc derivatives of 13 were prepared. The folded conformation might be expected to facilitate electron transfer among the components of the triad, and while this could enhance the quantum yield of the initial charge separated state, it might unfavorably affect the yield of the final D+-P-QT state and its lifetime. Unfortunately, photochemical or spectroscopic studies were not reported. 

They studied the pyrene/3,5-dimethoxy-7V,N-dimethylaniline combination in methanol. After the initial laser flash, fast electron transfer occurs resulting first in... 

---