Date on Master's Thesis/Doctoral Dissertation

12-1946

Document Type

Master's Thesis

Degree Name

M. Eng.

Department

Chemical Engineering

Committee Chair

Barnes, W. R.

Committee Co-Chair (if applicable)

Ernst, Robert Craig

Committee Member

Williams, Gordon C.

Subject

Pigments

Abstract

I. IMPROVED TECHNIQUES FOR WASHING IRON BLUE SUSPENSIONS

The investigation of several procedures for the speeding of the washing of iron blue suspensions to remove electrolytes is reported. The use of several techniques to coagulate blue particles in the colloidal range to cause more rapid settling was found to be of little value. A conventional Oliver filter and centrifugal clarifier were found to be unsatisfactory for clearing iron blue suspensions. Considerable advantage in washing by settling and decantation was obtained with the settling of the blue suspensions in relatively shallow vessels. A continuous washing procedure was developed whereby the blue suspension was circulated through a cloth tube system where liquid passed through the cloth. The simultaneous addition of water allowed a removal of electrolytes.

II. THE PREPARATION OF 0,0'-DICHLOROBENZIDINE FROM O-CHLORONITROBENZENE

The experimental work involved in the development of a procedure for the preparation of o,o'-dichlorobenzidine from o-chloronitrobenzene by liquid phase reduction using zinc and alkali is reported. Preliminary experiments in the investigation of reactions and general procedure using nitrobenzene to prepare benzidine are described. The development of the procedures using o-chloronitrobenzene in laboratory and pilot plant preparations is described. A process is presented whereby the o-chloronitrobenzene is reduced in a zinc, zinc oxide, water, alkali, alcohol mixture to the hydrazo compound. This material is separated from the reaction mixture, rearranged, and purified using acid solutions. Detailed instructions and a flow diagram are given together with an estimated raw material cost for the procedure.

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