Enamine Synthesis over Molecular Sieves, D-Optimal Design

4 Enamine Synthesis over Molecular Sieves, D-Optimal Design [23] 

A procedure for the formation of enamines by condensation of the parent ketone and secondary amines in the presence of molecular sieves was studied. The role of the molecular sieve is to trap the water formed. The enamine-forming reaction is acid catalyzed and both Bronsted acids and Lewis acids can be used. 

The reaction between methyl isobutyl ketone and morpholine was studied with two commercially available molecular sieves (Type 3 A and 5 A). The procedure was described for other systems but the conclusions as to the amounts of amines to be used were contradictory [24]. These ambiguities needed to be clarified. 

With a view to establishing suitable experimental conditions for preparative runs, the important experimental factors must be identified. To this end, a D-optimal design was used. The experimental variables considered are summarized in Table 4. It is seen that the variables describe both continuous and discrete variations. It is possible to use polynomial response function in such cases too, provided that the discrete variation is made to distinguish between only two alternatives. The model coefficients of the discrete variation is made to distinguish between only two alternatives. The model coefficients of the discrete variables describe the systematic variation of the response due to the alternatives. 

1 Cyclohexane was used as solvent k Two different types of acid catalysts were tested SA was a solid Silica-Alumina, a Lewis acid-type of catalyst used in petroleum cracking TFA was trifluoroactic acid, a proton acid. 

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