Process for removing cations from an isophoronenitrile product mixture

1. A process for removing a cation from an isophoronenitrile product mixture, said process comprising:

exchanging a cation other than hydrogen in said isophoronenitrile product mixture with a hydrogen cation, to obtain a purified product;

wherein said isophoronenitrile product mixture is from the preparation of isophoronenitrile from isophorone and hydrocyanic acid in the presence of a cation-containing catalyst in homogeneous phase in a reactor;

wherein said cation is from the cation-containing catalyst;

wherein said exchanging of the cation of the catalyst takes place by a cation exchanger without prior neutralization of the catalyst.

2. The process according to claim 1 , wherein the exchanging of the cation takes place in a cation exchanger apparatus which is designed to be single-stage or multi-stage.

3. The process according to claim 1 , wherein the exchanging of the cation takes place in a single-stage in only one cation exchanger apparatus.

4. The process according to claim 1 , wherein said cation exchanger is an immobilized cation exchanger which has, as a functional group, a sulfonic acid group which has been applied to a polystyrene matrix crosslinked with divinylbenzene.

5. The process according to claim 1 , wherein the exchanging of the cation of the catalyst takes place without neutralization of the catalyst, as first purification step after the reactor.

6. The process according to claim 2 , wherein a further work-up of the substance mixture takes place after the cation exchange apparatus by removal of a low boiler in a first column downstream of the cation exchanger, and in a second downstream column the purification of the isophoronenitrile is then carried out.

7. The process according to claim 2 , wherein a further purification of the isophoronenitrile after the cation exchange apparatus is carried out in a downstream column which contains a partial condenser placed on top or within the column.

8. The process according to claim 1 , wherein the catalyst is a soluble catalyst selected from the group consisting of a basic alkali metal compound, a basic alkaline earth metal compound and mixtures thereof;

wherein the catalyst is soluble in a solvent over which the reactants react to give the product isophoronenitrile.

9. The process according to claim 1 , wherein the catalyst is an alkali metal alcoholate.

10. The process according to claim 1 , wherein the catalyst is a 20-35% strength by weight sodium methanolate solution, dissolved in methanol.

11. The process according to claim 1 , wherein the preparation of isophoronenitrile is carried out in the presence of an inert solvent.

12. The process according to claim 1 , wherein a molar ratio isophorone/HCN is 19:1 to 1.5:1.

13. The process according to claim 1 , wherein a catalyst concentration, based on the amount of isophorone used, is in the range from 0.03 to 20% by weight.

14. The process according to claim 1 , wherein the preparation of isophoronenitrile is carried out in a stirred-tank, a stirred-tank cascade, a circulation reactor, a flow tube, one or more fixed-bed reactors or a column.

15. The process according to claim 6 , wherein a low boiler is methanol.

16. The process according to claim 6 , wherein a low boiler is selected from the group consisting of methanol, isophorone, water, HCN and mixtures thereof.

17. The process according to claim 1 , wherein the catalyst is sodium methanolate.

18. The process according to claim 1 , wherein the preparation of isophoronenitrile is carried out in the absence of an inert solvent.