Dimethylaniline photolysis

For example, PINO (i.e. >N—O"), generated from HPI by oxidation with Pb(OAc)4 (cf. Scheme 7) or by laser flash photolysis of (t-BuO)2 (cf. Scheme 5) at 266 nm, has been investigated in the oxidative A-demethylation of 4-X-substimted-Af,Af-dimethylanilines (X-DMAs) (Scheme 11). ... 

Figure 13. Decay curves of surfactant [Ru(bipy)3]+ (515 nm), formed from photolysis of surfactant [Ru(bipy)3]2+ and pyrene-N,iV-dimethylaniline, in various different environments (reproduced from ref. 328)...

The transient absorption spectrum of the OH adduct of dimethylaniline has a broad band centered at ca 380 nm. Decay of this species results in a growth of absorption in the 450 nm region where the radical cation has a strong absorption. Assignment of the radical cation spectrum was supported by eomparison with the spectra obtained in the eleetron-transfer reaction of sulfate radicals with DMA, and with DMA+ spectra generated by flash photolysis and eleetroehemical methods [101, 102]. The spectral characteristics of the observed transient species are summarized in Table 2. 

A,Ai-Dimethylaniline reacts with aldehydes under photochemical conditions to give acyl addition via the carbon atom of one of the methyl groups.The reaction of PhNMe2 and benzaldehyde, for example, gave PhN(Me)CH2CH(OH)Ph upon photolysis. 

Figure 2. Spectra of short-lived species in the laser photolysis of pyrene and dimethylaniline in C H CH OH and CTAB micelles. Insert oscilloscope time traces of pyrene...

The data show that the dynamics of this reaction involve hydrogen bonding effects . Fs-ps laser photolysis has been deployed to follow the details of the photoreduction of excited benzophenone by N,N-dimethylaniline in acetonitrile solution . Laser flash photolysis also has been used to examine the chromophore assisted peroxy-bond breakage in the case of a benzophenone perester . ... 

Photolysis of 3-phenyl-5(4H)-isoxazolone yields 2,5-diphenylpyrazine in 67% yield. Singlet excited isoxazol-5-one (224) undergoes both decarbonylation and decarboxylation to carbene intermediates, both of which are captured by alcohol or amine solvents. With triplet sensitisers an oxaziridine intermediate reacts with the solvent. N-Acylisoxazol-5-ones decarboxylate to yield singlet carbenes (225) which cyclise at the acyl oxygen to yield the isoxazoles (227), and the isothiazoles (228) are obtained via thioacyl carbenes (226) from N-thioacylisazol-5-ones. " The isolation of (229) as the main product from irradiation of benzophenone/N,N-dimethylaniline in the presence of the non-polymerising... 

Chesta et al. (1986, 1988) have shown that the photolysis of N,N-dimethylaniline can be coupled with uptake of the electron (or with direct electron transfer from the excited aniline singlet or triplet) by chlorinated benzenes and fragmentation of the resulting radical anion to chloride ion. Hydrogen-substituted benzene derivatives appear to be the other products. Bunce and Gallagher (1982) have shown that a similar aniline-sensitized dechlorination occurs with polychlorinated biphenyls. 

Neiman found that 2-azido-2 -nitrobiphenyl cyclizes readily to benzo[c]cinnoline-iV-oxide on photolysis or thermolysis. The intermolecular counterpart of this reaction now has been found to be equally facile in some cases. Heating a- or jS-naphthyl azide and p-nitroso-iV, -dimethylaniline at reflux in bromobenzene produces the azoxy compounds 40 and 41 in virtually quantitative yield (Np = naphthyl). 

Flash photolysis experiments show that [Ru(bipy)3] + ion once excited dispro-portionates into [Ru(bipy)3] + and [Ru(bipy)3]+ ions. The reaction is catalysed by oxidative quenchers like the paraquat dication, and also by reductive quenchers such as iV-dimethylaniline. ... 

One would think that electron transfer quenching in polar solvents would lead to the efficient formation of ion radicals. This event was first demonstrated in 1961 by flash photolysis studies of the perylene-N,N-dimethylaniline system (12). The transient absorption spectrum obtained was the superposition of that of the perylene anion and the amine cation. Since then several experiments were reported (13) and the time resolution of measurement has been improved to ns by using lasers (14). When these experiments were carried out in a quantitative way so that ion yield could... 

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