Abstract: Preparation of isobutene homopolymers or copolymers having a number average molecular weight of from 500 to 5 000 000 by polymerization of isobutene or an isobutene-comprising monomer mixture in the presence of a Lewis acid or a complex comprising a Lewis acid as polymerization catalyst, wherein the polymerization is carried out in the presence of at least one hemiacetal or full acetal which can be obtained by protic acid-catalyzed reaction of at least one C1-C12-hydrocarbyl alcohol with at least one aldehyde or ketone having from 1 to 12 carbon atoms.

Abstract: Preparation of isobutene homopolymers or copolymers having a number average molecular weight of from 500 to 5 000 000 by polymerization of isobutene or an isobutene-comprising monomer mixture in the presence of a Lewis acid or a complex comprising a Lewis acid as polymerization catalyst, wherein the polymerization is carried out in the presence of at least one hemiacetal or full acetal which can be obtained by protic acid-catalyzed reaction of at least one C1-C12-hydrocarbyl alcohol with at least one aldehyde or ketone having from 1 to 12 carbon atoms.

Abstract: An organic compound having at least one C—C double bond is epoxidized by means of hydrogen peroxide in the presence of at least one catalytically active compound and at least one solvent, wherein a product mixture comprising ?-hydroperoxyalcohols is reduced using at least one reducing agent.

Abstract: A sensor system for the detection or measurement relating to a chemical environment, comprising an optical fibre, an optical source for launching light into the optical fibre, the sensor system being adapted to let a gas, e.g. hydrogen derived from said chemical environment, diffuse into the optical fibre. The gas thereby alters the optical properties of the optical fibre. The system comprises optical signal detection and signal analysing means adapted for determining changes in the optical properties of the optical fibre due to the in-diffusion of the said gas. The signal analysis means is adapted to derive from the determined changes at least one characteristic value representing the chemical environment.

Abstract: A process for preparing propylene oxide comprises at least the following steps: (a) propene is reacted with a hydroperoxide in a solvent in the presence of a zeolite catalyst to give a mixture (M0), where the mixture (M0) comprises propylene oxide, solvent, unreacted propene, unreacted hydroperoxide and oxygen, (b) the propylene oxide is separated from the mixture (M0) so as to give a mixture (M1) which comprises unreacted propene and oxygen, (c) the mixture (M1) is brought into contact with a liquid medium comprising at least a solvent to give the mixtures (M2) and (M3), where the mixture (M3) comprises part of the unreacted propene and oxygen and the mixture (M2) comprises solvent and residual propene, and ?the mixture (M3) which has been separated off and comprises unreacted propene and oxygen has a ratio of oxygen to propene such that the mixture (M3) is not ignitable, and ?the mixture (M2) is fed to at least one reaction of propene with hydroperoxide.

Abstract: A process for preparing propylene oxide comprises at least the following steps:

Abstract: A process for preparing propylene oxide comprises at least the following steps:

Abstract: An organic compound having at least one C—C double bond is epoxidized by means of hydrogen peroxide in the presence of at least one catalytically active compound and at least one solvent, wherein a product mixture comprising &agr;-hydroperoxyalcohols is reduced using at least one reducing agent.