25052-92-0

Upstream product

• 121-69-7 N,N-dimethyl-aniline 
• 106-51-4 p-benzoquinone 
• 121-69-7 dimethyl-phenyl-ammoniumyl 
• 119-61-9 benzophenone anion 
• 21773-56-8 4,4'-dichlorobenzophenone radical anion 
• 81439-06-7 4-chlorobenzophenone radical anion 
• 34493-36-2 4,4'-dimethoxybenzophenone radical anion 
• 22673-52-5 4-fluorobenzophenone radical anion 
• 32555-06-9 4-methylbenzophenone radical anion 
• 60466-08-2 4-methoxybenzophenone radical anion 
• 7175-54-4 cumyl peroxy radical 

Relevant academic research and scientific papers

Probing the compound I-like reactivity of a bare high-valent oxo iron porphyrin complex: The oxidation of tertiary amines

The mechanisms of oxidative N-dealkylation of amines by heme enzymes including peroxidases and cytochromes P450 and by functional models for the active Compound I species have long been studied. A debated issue has concerned in particular the character of the primary step initiating the oxidation sequence, either a hydrogen atom transfer (HAT) or an electron transfer (ET) event, facing problems such as the possible contribution of multiple oxidants and complex environmental effects. In the present study, an oxo iron(IV) porphyrin radical cation intermediate 1, [(TPFPP)?+Fe IV=O]+ (TPFPP = meso-tetrakis (pentafluorophenyl) porphinato dianion), functional model of Compound I, has been produced as a bare species. The gas-phase reaction with amines (A) studied by ESI-FT-ICR mass spectrometry has revealed for the first time the elementary steps and the ionic intermediates involved in the oxidative activation. Ionic products are formed involving ET (A?+, the amine radical cation), formal hydride transfer (HT) from the amine ([A(-H)]+, an iminium ion), and oxygen atom transfer (OAT) to the amine (A(O), likely a carbinolamine product), whereas an ionic product involving a net initial HAT event is never observed. The reaction appears to be initiated by an ET event for the majority of the tested amines which included tertiary aliphatic and aromatic amines as well as a cyclic and a secondary amine. For a series of N,N-dimethylanilines the reaction efficiency for the ET activated pathways was found to correlate with the ionization energy of the amine. A stepwise pathway accounts for the C-H bond activation resulting in the formal HT product, namely a primary ET process forming A?+, which is deprotonated at the α-C-H bond forming an N-methyl-N-arylaminomethyl radical, A(-H)?, readily oxidized to the iminium ion, [A(-H)]+. The kinetic isotope effect (KIE) for proton transfer (PT) increases as the acidity of the amine radical cation increases and the PT reaction to the base, the ferryl group of (TPFPP)FeIV=O, approaches thermoneutrality. The ET reaction displayed by 1 with gaseous N,N-dimethylaniline finds a counterpart in the ET reactivity of FeO+, reportedly a potent oxidant in the gas phase, and with the barrierless ET process for a model (P)?+FeIV=O species (where P is the porphine dianion) as found by theoretical calculations. Finally, the remarkable OAT reactivity of 1 with C6F 5N(CH3)2 may hint to a mechanism along a route of diverse spin multiplicity.

Efficient unimolecular deprotonation of aniline radical cations

Deprotonation of the radical cations of aromatic amines, such as anilines, generally occurs much more slowly than other fragmentation reactions. Here we report a stereoelectronic effect involving twisting of the anilino group out of the plane of the benze

Chemistry of the t-butoxyl radical: Evidence that most hydrogen abstractions from carbon are entropy-controlled

Absolute rate constants and Arrhenius parameters for hydrogen abstractions (from carbon) by the t-butoxyl radical (tBuO·) are reported for several hydrocarbons and tertiary amines in solution. Combined with data already in the literature, an an

Mechanisms of hydrogen-, oxygen-, and electron-transfer reactions of cumylperoxyl radical

Rates of hydrogen-transfer reactions from a series of para-substituted N,N-dimethylanilines to cumylperoxyl radical and oxygen-transfer reactions from cumylperoxyl radical to a series of sulfides and phosphines have been determined in propionitrile (EtCN) and pentane at low temperatures by use of ESR. The observed rate constants exhibit first-order and second-order dependence with respect to concentrations of N,N-dimethylanilines. This indicates that the hydrogen- and oxygen-transfer reactions proceed via 1:1 charge-transfer (CT) complexes formed between the substrates and cumylperoxyl radical. The primary kinetic isotope effects are determined by comparing the rates of N,N-dimethylanilines and the corresponding N,N-bis(trideuteriomethyl)anilines. The isotope effect profiles are quite different from those reported for the P-450 model oxidation of the same series of substrates. Rates of electron-transfer reactions from ferrocene derivatives to cumylperoxyl radical have also been determined by use of ESR. The catalytic effects of Sc(OTf)3 (OTf = triflate) on the electron-transfer reactions are compared with those of Sc(OTf)3 on the hydrogen- and oxygen-transfer reactions. Such comparison provides strong evidence that the hydrogen- and oxygen- transfer reactions of cumylperoxyl radical proceed via a one-step hydrogen atom and oxygen atom transfer rather than via an electron transfer from substrates to cumylperoxyl radical.

Picosecond Dynamics of Nonadiabatic Proton Transfer: A Kinetic Study of Proton Transfer within the Contact Radical Ion Pair of Substituted Benzophenones/N,N-Dimethylaniline

Picosecond absorption spectroscopy has been employed in the study of the dynamics of proton transfer within substituted benzophenones/N,N-dimethylaniline contact radical ion pairs. The reactions were investigated in the solvents cyclohexane, benzene, and dimethylformamide. The correlation of the reaction rates with the change in free energy reveals that the reaction pathway corresponds to a nonadiabatic process, that is the reaction proceeds by proton tunneling. In nonpolar solvents, an inverted region is observed in the proton-transfer process.

Dynamics of anilinium radical α-heterolytic fragmentation processes. Electrofugal group, substituent, and medium effects on desilylation, decarboxylation, and retro-aldol cleavage pathways

A single electron transfer (SET) photosensitization technique in conjunction with time-resolved, laser spectroscopy has been employed to generate and kinetically analyze decay processes of anilinium radicals derived by one-electron oxidation of α-anilinocarboxylates, β- anilinoalcohols, and α-anilinosilanes. In this manner, the rates of unimolecular decarboxylation of aniliniumcarboxylate radicals were determined to be in the range 106 - 107 s-1 and dependent upon solvent polarity, the nature of the metal cation, and substituents on the aniline ring, nitrogen, and α-carbon. In addition, kinetic analysis of base-induced retro-aldol fragmentations of cation radicals arising by SET oxidation of β- anilinoalcohols has shown that they occur with bimolecular rate constants which vary from 104 to 105 M-1 s1. These values are close to those for α-deprotonation reactions of related N,N-dialkylanilinium radicals. The retro-aldol fragmentation rates, like those for α-decarboxylation, also vary in a patterned way with changes in arene ring, nitrogen, and α- and β- carbon substituents. An investigation of the dynamics of methanol-promoted reactions of α-(trimethylsilyl)methyl-substituted anilinium radicals, has demonstrated that a change in the nitrogen substituent from alkyl to acyl causes an ca. 10-fold increase in the desilylation rate. Parallel photochemical studies have been conducted to gain chemical evidence to support assignment of the anilinium radical decay pathways in the LFP experiments and to demonstrate the preparative consequences of the kinetic results. First, clean formation of products derived by coupling of the (N- methylanilino)methyl radical in photochemical reactions of 1,4- dicyanobenzene with either tetra-n-butylammonium N-methyl-N-phenylglycinate or β-(N-methyl-N-phenyl)aminoethanol shows that the respective decarboxylation and retro-aldol cleavage processes occur with exceptionally high efficiencies. Second, in accord with the high rates observed for aminium radical decarboxylation and base-induced retro-aldol fragmentation, tethered cyclohexenone - α-aminocarboxylates and - β-aminoethanols undergo high- yielding SET-promoted photocyclization reactions under both direct and SET- sensitized conditions. Last, results which depict how the rates of aminium radical α-fragmentation correlate with quantum efficiencies of SET-promoted reactions of tertiary amines and amides have come from a study of photocyclization reactions of N-(aminoethyl)- and (amidoethyl)phthalimides. The quantum yields for these SET-promoted processes are observed to vary with the electrofugal group and nitrogen substituent in the manner predicted on the basis of the LFP-determined fragmentation rates.

Photoreduction of Triplet Benzophenone by Tertiary Amines: Amine Molecular Structure and Ketyl Radical Yield

The photoreduction of triplet benzophenone by 14 tertiary amines was investigated. The ketyl radical yields do not correlate with the quenching rate constants, nor with the electron donor propensity of the amines. Individual structural features of the amines seem to determine the photoreduction yields.