ISSN:
1573-9171
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Chemie und Pharmazie
Notizen:
Summary 1. 2-Acetylthiophene, when polarographed within a broad range of pH of the solutions, behaves similarly to aromatic aldehydes and ketones-it is reduced on a drop electrode to the corresponding alcohol and pinacone. 2. Bromine in the 4-position of bromoacetylthiophene is not reduced, but only facilitates the reduction of the keto group. 3. Bromine in the 5-position of bromoacetylthiophene is reduced before the reduction of the keto group. E1/2 of the wave of cleavage of the C-Br bond depends on the pH; in alkaline medium, a drop in the current is observed on the limiting current of this wave. Cleavage of the C-Br bond occurs only after protonation of the molecule, which occurs in the state of adsorption upon the electrode, which explains the unusual nature of the wave corresponding to this process. 4. In the case of 4, 5-dibromo-2-acetylthiophene, before reduction of the keto group there is an electrochemical cleavage of the C -Br bond only at the 5-position; this process is preceded by surface protonation of the molecule.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF01083789
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