A COMPARATIVE STUDY OF ALKYLATION OF ANILINE, INDOLE AND PHENOL OVER Ni1-XMnXFe2O4 TYPE FERRITE SYSTEM

ABSTRACT

Ferrites are mixed metal oxides with spinel structure having interesting structural, electrical, magnetic and catalytic properties. A series of Ni-Mn type ferrospinels with general formula Ni_1-xMn_xFe₂O₄ were prepared by low temperature co-precipitation method and characterized by adopting various physico-chemical methods. The catalyst system showed different catalytic activity trends for methylation of aniline, phenol and indole using methanol as alkylating agent. Lower ‘x’ values promote N-methylation of aniline, whereas higher ‘x’ values leads to increased rate of ortho methylation of phenol and 3-methylindole formation. An attempt has been made to interpret the observed trends based on the variation in the surface acido-basic properties of the ferrospinel system. Cation distribution in the ferrospinel lattice influences the acid-base properties. Progressive substation of Ni²⁺ by Mn²⁺ increases the acidity with a concomitant decrease in basicity. In the case on aniline methylation, surface basicity plays a domination role, whereas for methylation of phenol and indole surface acidity plays a dominating role.

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