Abstract: Cyclic products are prepared by selective olefin metathesis of bifunctional or polyfunctional substrates in the presence of one or several homogeneous or heterogeneous metathesis catalysts in a reaction medium. The invention is characterized in that the substrates contain two or more functional groups in the form of substituted or non-substituted alkene or alkyne units and in that the reaction medium essentially consists of compressed carbon dioxide. Also disclosed is the preparation of cyclic or polymer products according to the disclosed process, the reaction temperature and total pressure being matched to ensure that the density of the reaction medium lies in a range d=0.2-1.5 g·cm−3 and that the product distribution is essentially controlled by the reaction medium density.

Abstract: The invention relates to a device for protecting selective cutting machines against overload, in which the selective cutting machine has cutting tools, in particular cutting rollers, rotatably supported on a pivotable cantilevered arm, and both the cutting tools and the cutting arm are connected to separate drive mechanisms. At least one strain or deformation measuring sensor is disposed on the pivotable cantilevered arm, and its signals are delivered to an evaluation circuit; the evaluation circuit is connected via control lines at least to the drive mechanisms of the cutting arm and the cutting tool.