53655-20-2Relevant academic research and scientific papers
Photochemistry of bifunctional chain molecules containing benzophenone and anilino chromophores. Magnetic field and magnetic isotope effects on lifetimes of triplet biradicals
Nakagaki, Ryoichi,Yamaoka, Masaharu,Mutai, Kiyoshi
, p. 347 - 355 (2007/10/03)
The decay time of biradicals containing a benzophenone ketyl and an anilino-alkyl radical has been examined by nano-second laser photolysis in the presence of external magnetic fields up to 1 T. When sites with high spin densities are labeled with heavy carbon, noticeable magnetic isotope effects are observed on the decay kinetics for biradicals. Small kinetic effects are observed for deuterated species. The obtained results can be interpreted in terms of spin-lattice relaxation due to anisotropic hyperfine and dipole- dipole interactions. Procedures for preparing labeled species are also described.
Aromatic Rearrangements in the Benzene Series. Part 3. Rearrangement of Isotopically Labelled Phenyl Benzoates: Intermolecularity of the ortho-Directed Rearrangement. Criteria for Determining the Intra-/Inter-molecularity of Aromatic Rearrangements
Dawson, Ian M.,Hart, Lionel S.,Littler, John S.
, p. 1601 - 1606 (2007/10/02)
The rearrangement of a mixture of Ph13COOPh and PhCO18OPh (with some unlabelled ester) catalysed by anhydrous AlBr3 in homogeneous solution in chlorobenzene has been examined.Contrary to expectations, more of the 2-hydroxybenzophenone is formed intermolecularly than of the 4-hydroxybenzophenone at the beginning of the reaction, contradicting earlier views that a high ortho : para ratio in such reactions indicates the operation of an intramolecular mechanism.A mechanism is proposed for this stage of the rearrangement involving a cyclic six-membered transition state originating from one molecule of phenyl benzoate and one of Ph-C(OPh)=O+-Al-Br3, allowing C-acylation by the benzoyl moiety of the catalyst-ester complex to compete with bimolecular ester interchange.This C-acylation can only occur at the ortho-position of the phenoxy-ring of the (uncomplexed) ester molecule, because of steric requirements.This step of the rearrangement is thus necessarily intermolecular.Criteria for judging the intra- or inter-molecularity of aromatic rearrangements are also briefly discussed.
