Degussa Aktiengesellschaft

Axel Kleeman

Gunter Prescher

Gebhard Ritter

Karl-Heinz Drauz

Herbert Klenk

Horst Weigel

Hans-Joachim Hasselbach

Aqueous solutions of free, neutral .alpha.-amino acids are recovered from aqueous solutions of their alkali-metal salts. Two equally large rectifying columns filled with a strongly acidic cation exchanger in the H.sup.+ form are used, the discharge of the first column being connected to the head of the second column. The solution of the alkali-metal salt is at first delivered to the head of the first column, then the residual solution, reduced by the alkali-metal cations adsorbed in the exchanger, is displaced to the second column by means of the addition of water. A product-free forerun is first separated at the discharge of the second column and, when free .alpha.-amino acid begins to exit in the flow-off from the second column, the receiver is changed and the delivery of water to the head of the first column continues further until a mixed pH between 5 and 7 has been achieved in the receiver. Then, the previously first column is decoupled and regenerated, the previously second column, which is now the first column, is coupled to a freshly regenerated column as second column and the entire process is repeated as often as desired.

Method for the recovery of aqueous solutions of free, neutral

The nuclear hydroxylation of phenol can be carried out in an industrially very simple manner and with at least the yields obtained with the known methods as well as with very good selectivities by means of using aqueous hydrogen peroxide with the simultaneous addition of sulfur dioxide or selenium dioxide as catalyst.

Method of producing catechol and hydroquinone

The nuclear hydroxylation of substituted phenols is performed by using aqueous hydrogen peroxide in the presence of sulfur dioxide or selenium dioxide as catalyst in a simple manner with very good space-time yields and good product yields.

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Muhlheim, Germany

Axel Kleeman