Abstract: 2-Substituted-5-(1-alkyl-piperid-yl)-1,3-dioxanes of the formula I ##STR1## wherein R= ##STR2## R.sup.1 =--C.sub.n H.sub.2n+1, --OC.sub.n H.sub.2n+1, --OOCC.sub.n H.sub.2n+1, --COC.sub.n H.sub.2n+1, --OOCOC.sub.n H.sub.2n+1, --F, --Cl, --Br, --I, --NO.sub.2, --CN --(CH.sub.2).sub.2 CN, ##STR3## and n=1 to 10, are novel liquid crystalline compounds, which can be produced in high yields by means of reacting 2-(1-alkyl-piperid-4-yl)-propane-1,3-diols with aldehydes in the presence of acid catalysts, such as p-toluenesulfonic acid, mineral acids and Lewis acids. Because of their high thermal and chemical stability, which is also transferred to mixtures, the compounds of the formula I are very well suited for utilization in optoelectronic displays.

Abstract: A method for removal of oxygen dissolved in water, especially from reservoir drinking water, and for preservation purposes based on hydrazine, having no organic activators and assuring a high reaction velocity with respect to dissolved oxygen within a broad pH-range at low temperature and without a time-dependent reduction of its effectiveness.Cationic and anionic complexes of trivalent cobalt with inorganic ligands, or mixtures thereof, are used as activators. Preferred activators are (Co(NH.sub.3).sub.5 Cl)Cl.sub.2 and Na.sub.3 Co(NO.sub.2).sub.6.Hydrazine solutions with these activators are suitable for the removal of oxygen from gases.

Abstract: The method for improving the initial activity of activated hydrazine is used as corrosion protection for reservoir drinking water and for the wet preservation of installation parts no longer in use. It is the object of the invention to increase the initial activity of hydrazine solutions, activated with complexes of trivalent cobalt, with respect to oxygen dissolved in water, and to develop a suitable method for the activator-rich hydrazine solution. The object is accomplished in that trivalent phenols, preferably pyrogallol, are added in small amounts to the activator-rich hydrazine solution.

Abstract: The method for improving the initial activity of activated hydrazine, is used as corrosion protection for reservoir drinking water and for the wet preservation of installation parts, which are no longer being used. It is the goal of the invention to improve the initial activity of hydrazine solutions, which are activated with complexes of trivalent cobalt, with respect to oxygen dissolved in water, and to lower the activator concentration; the object of the invention being to use a suitable coactivator. The object is accomplished in that the activator-rich hydrazine solution additionally contains 2-amino-4-nitrophenol or 2-acetamino-4-nitrophenol or mixtures thereof as coactivator.