Hoechst Aktiengesellschaft

Heinz Schutte

Konrad Baessler

Kurt C Habig

Lothar Schulz

Nitrosation agent(s), contained as by-products in nitrated aromatic compounds after nitration with nitric acid or nitration acid, are removed by a water treatment, wherein the water is distilled off at least partially in vapor form, advantageously under reduced pressure. In the further reaction of the nitrocompounds treated in this manner undesired nitrosamines are practically not formed. The process is especially suitable for the manufacture of 4-di-n-propylamino-3,5-dinitrobenzotrifluoride (Trifluralin), a valuable herbicide, substantially free from nitrosamine(s).

Method for removing nitrosation agent(s) from a nitrated aromatic

A separator for separating liquids immiscible with each other and containing solids heavier than the heavier liquid, includes a rotating conic drum into which the liquids are injected. The drum has a circumferential wall formed of two oppositely-directed conic surfaces joined at the bases at an inclination angle to form an equator; and openings are provided at the equator for the heavier liquid and the solids to pass. Preferably, the drum has a star-like cross section with the interior wall extending inward at an angle from either side of each opening. The separator can include a weir or paring disc disposed radially in the static pressure chamber at a nominal level of the heavier liquid to maintain proper pressure of the heavier fluid to prevent the lighter liquid from discharging into the static pressure chamber. Alternatively, a sensor and valve arrangement can be provided to achieve this benefit.

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Hofheim am Taunus, Germany

Heinz Schutte