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The electrochemical oxidation of theophylline was investigated by controlled potential electrolysis in two different organic solvents and in water for comparison. The anodic oxidation was monitored by cyclic voltammetry in situ and UV‐Vis spectrophotometry ex situ and the final electrolyzed solutions were analyzed by tandem mass spectrometry after chromatographic separation with an HPLC‐PDA‐ESI‐MS/MS system. The main oxidation products evidenced as the main diode array chromatographic peaks were tentatively assigned to dimeric forms of theophylline, two of which have never been reported before, on the base of retention time, UV‐Vis spectrum, m/z ratio in both positive and negative ESI modes and fragmentation pattern. Two chemical paths following the primary mono‐electronic anodic oxidation of theophylline to the final evidenced oxidation products have been proposed. [ABSTRACT FROM AUTHOR]

The cathodic reduction of dicationic imidazolium bromides, whose spacer is either an aliphatic chain or a xylyl group, leads to the formation of the corresponding N‐heterocyclic carbenes (NHCs), which were isolated as the corresponding thiones, after reaction with elemental sulfur. The behaviour of the dications was compared with the corresponding monocations. The behaviour of dicarbenes depends on the nature of the spacer. This study evidenced that dicarbenes deriving from xylyl dications are less stable than the corresponding aliphatic ones (giving lower yields in thiones), due to a debenzylation reaction. On the other hand, the yields in thiones starting from aliphatic dications are higher than the corresponding monocations, suggesting a cooperative reduction at the electrode of the two imidazolium moieties. The cathodic process was confirmed using the co‐electrogenerated hydrogen to reduce 2,2,2‐trifluoroacetophenone to the corresponding alcohol. [ABSTRACT FROM AUTHOR]

Electrochemical studies on a series of new conjugated oligothiophene derivatives are reported. The molecular architectures (D−A and A−D−A) of these compounds present different donor cores (thiophene, bithiophene) with different numbers of 3‐octylthiophene units (that act as π‐bridge and solubilizing components). The acceptor end groups adopted were, in all the cases, ethyl cyanoacrylate units. The results from voltammetric experiments confirm the close relationship between the structure of these oligothiophenes and their electrochemical behavior. Furthermore, we carried out quantum mechanical calculations to be able to obtain the HOMO/LUMO characteristics of some of our compounds in order to confirm our hypotheses on their electrochemical behavior. Moreover, the roles of the oligothiophene backbone and the ethyl cyanoacrylate group in cyclic voltammetry were elucidated by carrying out two different electrolyses at anodic and cathodic peak potentials. In particular, we were successful in the anodic dimerization of a tetrathiophene (D−A) to an octithiophene (A−D−A) (in high yield) with a considerable shortening of the chemical synthesis. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of caffeine, never carried out previously, yielded in DMF–Et4 NBF4 N -formyl- N ,1-dimethyl-4-(methylamino)-1 H -imidazole-5-carboxamide, a highly functionalized imidazole product derived from the opening of the uracil ring. This reactivity is different from that of the methylated salt of caffeine, the cathodic reduction of which leads to the opening of the imidazole ring. Moreover, the product obtained by cathodic reduction, formylated at the exocyclic amide nitrogen, is different from that formed by treatment in an aqueous solution of sodium hydroxide followed by formylation. The latter is formylated at the exocyclic amine nitrogen. [ABSTRACT FROM AUTHOR]