Bayer Aktiengesellschaft

Kurt Klinkmann

Kuno Wagner

Raimund Wambach

Michael Herzhoff

Paul R Wambach, Deceased

Gerhard Burmeister

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,

Process for the preparation of optionally substituted benzyl-benzenes

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.

Process for purifying the methanol employed in the preparation of

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.

Process for the purification of aqueous solutions of low molecular

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.

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Nettersheim, Germany

Kurt Klinkmann