Aromatic amination of refined rice bran oil previously epoxidized using Novozym 435

Abstract

Objective: To synthesize aromatically aminated rice bran oil (APA) using a chemo-enzymatic epoxidation based on Novozym 435 followed by p-xylenediamine insertion.

Design/methodology/approach: Refined APA was epoxidized using H₂O₂/Novozym 435. The resulting epoxidized rice bran oil (eAPA) was functionalized with the aromatic diamine p-xylylenediamine via epoxy ring cleavage (X-eAPA), using ZnCl₂ as catalyst. Iodine value (IY), saponification value (IS) and oxirane oxygen content (COO) were determined to evaluate structural changes of the oils. APA, eAPA and X-eAPA were identified using FTIR, ¹H and ¹³C NMR.

Results: IY, IS and COO values suggested that the synthesis of eAPA and X-eAPA were effective. The increase in molecular weight in eAPA indicates formation of ~6 epoxy rings per original triglyceride. The COO value of X-eAPA was reduced by 22% compared to that of eAPA, implying that an effective aromatic amination was achieved. FTIR, ¹H and ¹³C NMR spectroscopy studies confirmed the epoxidation and amination of APA.

Limitations on study/implications: X-eAPA may be a feasible precursor to obtain high added-value products, as polymers or corrosion inhibitors.

Findings/conclusions: Refined rice bran oil partially aromatic aminated was synthesized in two steps, under mild conditions. Epoxidized rice bran oil was obtained using H₂O₂/Novozym 435, to be immediately functionalized with the aromatic diamine p-xylylenediamine.

Keywords: Epoxidation, amination, agro-industrial by-products.