2,5-Dimethyl-1,4-bis(carboxyalkyl)benzenes were prepared in almost quantitative yield
by alkylation of malonic esters from 2,5-dimethyl-1,4-dibromomethylbenzene obtained by
bromomethylation of 1,4-dimethylbenzene. The methyl groups on the central benzene ring
induce intramolecular, regiospecific cycloeliminations leading selectively to the diketones,
the precursors of the corresponding 1,5-dihydro-s-indacenes, which also were obtained in
very high yield. These new ligand precursors were easily converted to the mono- or dianions,
which were characterized by means of the mono- or disilylated compounds. Disilylation occurs
in cis and trans position. The structure of the trans-1,5-bis(trimethylsilyl)-2,6-diethyl-4,8-dimethyl-s-indacene was obtained by X-ray diffraction. Hexaalkyl-1,5-dihydro-s-indacenes
underwent regioselective monosilylation and regiospecific and stereoselective disilylation.
Disilylation of the less hindered tetraalkyl-1,5-dihydro-s-indacenes was regioselective and
stereoselective.
SummaryModified electrodes with poly(2,2'-dithiodianiline),PDTDA, were prepared from the corresponding monomer by cyclic voltammetry between 0.0 V and 1.5-1.6 V on gold or stainless steel respectively. The potentiodynamic method proved to bring about good quality and adherent thin films. The wide potential window shown by this modified electrode allowed attempting the insertion of copper in the polymeric matrix using several strategies. The response of this modified electrode copper was checked in the presence of γ-aminobutyric acid (GABA). Copper loaded on PDTDA/Au electrodes showed the highest sensitivity along with a stable and reproducible response for the detection of GABA. The surface morphology and composition analysis by SEM and XPS shows that copper is deposited in the polymeric matrix as uniformly scattered microparticles. The surface of these particles is mainly composed of Cu(I) species.
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