Abstract: A measuring transducer for process instrumentation that comprises a sensor for sensing a physical or chemical variable, wherein the sensor includes at least one electrical element embedded in a substrate comprising semiconducting material and is electrically separated therefrom by a blocked PN junction during normal operation. In order to monitor the condition of the sensor, the PN junction is connected in the conducting direction in a test mode, and the electrical property of the PN junction, i.e., the forward voltage, is determined and used to monitor the sensor condition. Additionally, a temperature sensor mounted on the sensor can be monitored by determining, based on the dependence of the forward voltage on the temperature, a comparative value for the temperature sensed by the temperature sensor. If major differences occur, a conclusion can be reached that there is a failure of the sensor, and a corresponding error message can be output over a field bus.

Abstract: The present invention relates to a catalyst system comprising: a) an organoaluminum compound, b) a metal compound selected from subgroups IV to VI of the periodic system, c) a reactivator in a molar ratio of 0.5 to 100 relative to compound b), wherein said reactivator comprises a characterized in that a mono- or dihalocarboxylic acid alkyl ester of the following formula: wherein X is a C1-6 alkyl or C1-6 alkoxy group, Y is Cl, Br or H, Z is Cl or Br and R is a C1-6 alkyl group.

Abstract: Arylidene-substituted alkylcycloalkanones are prepared from alkyl-substituted cycloalkanones by reaction with aromatic carbonyl compounds in the presence of a basic catalyst and water.

Abstract: 2-Chloroacrylonitrile is prepared in a particularly advantageous and readily industrially practicable manner by chlorinating acrylonitrile and then thermally cleaving the 2,3-diehloropropionitrile formed, by chlorinating acrylonitrile in the presence of a catalyst system comprising dimethylformamide and pyridine and/or pyridine derivatives and subjecting the resulting crude 2,3-dichloropropionitrile to thermal cleavage in the presence of the same catalyst system without the addition of further catalysts.

Abstract: 2-Substituted cyclopentanones are prepared by reacting adipic ester with an alkoxide in the presence of an inert solvent, thus obtaining a salt of the cyclopentanone-2-carboxylic ester, alkylating this without isolation, thus obtaining a 2-alkyl-cyclopentanone-2-carboxylic ester and, without isolation, hydrolysing and decarboxylating this by treatment with an acid and heating.

Abstract: A particularly advantageous process for the preparation of 2,2-dialkyl-arylidene-cycloalkanones is characterized in that 2-alkyl-arylidene-cycloalkanones are reacted with alkyl halides in the presence of metal hydroxides and tertiary alcohols.