1450-72-2Relevant articles and documents
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Cullinane,Edwards
, p. 3016,3018 (1957)
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Dinuclear Metal Complexes. Part 2. Synthesis, Characterisation, and Electrochemical Studies of Macrocyclic Dicopper(II) Complexes
Mandal, Sanat Kumar,Nag, Kamalaksha
, p. 2429 - 2434 (1983)
The synthesis, characterisation, and electrochemical studies of dicopper(II) complexes 1>2.nH2O of the macrocycle 7,11;19,23-dimetheno-9,21-dimethyl-tetra-azacycloicosa-5,7,9,12,17,19,21,24-octaene-25,26-diol (H2L1), and of some 6,12,18,24-substituted (Me4; Prn4; Ph4; Ph, Me, Ph, Me) derivatives have been carried out.These compounds undergo sequential one-electron transfers at two different potentials.For all of these compounds, except for 1>2.2H2O, two reversible or almost reversible reduction steps have been observed in acetonitrile medium using a hanging mercury drop electrode.In the case of 1>2.2H2O, the second couple became obscured due to the presence of an adsorption phenomenon or secondary electrode reaction.However, in NN-dimethylformamide (dmf) medium, satisfactory voltammograms have been obtained only with 1>2.2H2O.The mixed-valent complexes are considerably more stable in acetonitrile than is IICuIL1>+ in dmf.The potentials of the first reduction step (E1) remain practically invariant throughout the series and are independent of the extent of magnetic interactions in the dicopper(II) complexes.The potentials of the second reduction step (E2) vary with the alkyl and aryl groups present, and a linear plot has been obtained for E2 vs. the Hammett function ?m.On the basis of previously reported observations and the present study it is inferred that in acetonitrile medium the unpaired electron in the mixed-valent complexes remains localised on one of the copper atoms.
REARRANGEMENT OF DIMETHYLPHENYLACYLATES USING ZEOLITES
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Page/Page column 9-10; 15, (2021/08/14)
The present invention relates to a Fries rearrangement of specific dimethylphenylacylates to form the desired respective hydroxyaryl ketones having two methyl groups bound to the aromatic ring. It has been found that the process is surprisingly very specific in view of the number and position of the methyl group(s) bound to the aromatic ring.
Substrate substitution effects in the Fries rearrangement of aryl esters over zeolite catalysts
Bonrath, Werner,Létinois, Ulla,Lin, Ronghe,Medlock, Jonathan,Mitchell, Sharon,Netscher, Thomas,Pérez-Ramírez, Javier,Stemmler, René T.
, p. 4282 - 4292 (2020/07/30)
The catalytic transformation of aryl esters to hydroxyacetophenones via Fries rearrangement over solid acids is of interest to avoid the use of corrosive and toxic Lewis and Br?nsted acids traditionally applied. Microporous zeolites are known to catalyze the reaction of simple substrates such as phenyl acetate, but their application to substituted derivatives has received limited attention. To refine structure-activity relationships, here we examine the impact of various parameters including the solvent polarity, water content, acidic properties, and framework type on the reaction scheme in the Fries rearrangement of p-tolyl acetate over common solid acids. The results confirm the importance of providing a high concentration of accessible Br?nsted acid sites, with beta zeolites exhibiting the best performance. Extension of the substrate scope by substituting methyl groups in multiple positions identifies a framework-dependent effect on the rearrangement chemistry and highlights the potential for the transformation of dimethylphenyl acetates. Kinetic studies show that the major competitive path of cleavage of the ester C-O bond usually occurs in parallel to the Fries rearrangement. The possibility of sequentially acylating the resulting phenol depends on the substrate and reaction conditions.
