Abstract: Optionally substituted benzyl-benzenes can be prepared by reaction of a benzyl alcohol of the formula ##STR1## with a benzene of the formula ##STR2## in which R.sup.1, R.sup.2, R.sup.3, R.sup.4 and R.sup.5 independently of one another denote hydrogen, C.sub.1 -C.sub.4 -alkyl, C.sub.1 -C.sub.4 -alkoxy, fluorine or chlorine, where R.sup.1, R.sup.2, R.sup.3 and R.sup.4 independently of one another may also represent hydroxyl and R.sup.5 may additionally be C.sub.5 -C.sub.8 -alkyl,R.sup.6 represents hydrogen or one of the groups ##STR3## R.sup.8 denotes hydrogen or hydroxymethyl, in a ratio of 1 mole of benzene to 0.8-5 moles of benzyl alcohol in the presence of an amount of activated bleaching earth of 0.05-5% by weight, relative to the amount of benzyl alcohol, at a temperature between 90.degree. C. and 140.degree. C. in the presence of a diluent.

Abstract: The invention relates to a process for purifying, by treatment with an acid ion exchanger and, if desired, a basic ion exchanger, the methanol employed in the preparation of formaldehyde.

Abstract: The invention is directed to a process for the purification of aqueous solutions of low molecular weight polyhydroxyl compounds containing calcium or lead compounds or mixtures thereof. Methanol and a precipitant for calcium and/or lead ions in a quantity equivalent to the ions to be removed are added to the solutions. The deposits thus formed are removed and the residual solutions are treated with a cation exchanger followed by distillation of the low-boiling fractions. The distillation sump which essentially contains the low molecular weight polyhydroxyl compounds is then treated with an anion exchanger.

Abstract: A method of preparing biuret polyisocyanates by reacting diisocyanates with up to about 0.4 mol per mol of diisocyanate of a monohydric tertiary alcohol in the presence of from about 0.001 to about 0.1 mol per mol of tertiary alcohol of a catalyst consisting of salts and salt mixtures of nitrogen containing bases and organic or inorganic acids at a temperature of between about 60.degree. and about 210.degree. C. The volume/time yield of biuret polyisocyanate according to this process is from 3 to 5 times greater than volume/time yields obtained with comparative known methods.