**One-Pot Solvent-Free Synthesis of** *N,N***-Bis(2-Hydroxyethyl) Alkylamide from Triglycerides Using Zinc-Doped Calcium Oxide Nanospheroids as a Heterogeneous Catalyst**

#### **Dinesh Kumar 1,\*, Chan Hee Park 1,2,\* and Cheol Sang Kim 1,\***


Received: 1 September 2019; Accepted: 13 September 2019; Published: 14 September 2019

**Abstract:** *N,N*-Bis(2-hydroxyethyl) alkylamide or fatty acid diethanolamides (FADs) were prepared from a variety of triglycerides using diethanolamine in the presence of different transition metal-doped CaO nanocrystalline heterogeneous catalysts. The Zn-doped Cao nanospheroids were found to be the most efficient heterogeneous catalyst, with complete conversion of natural triglycerides to fatty acid diethanolamide in 30 min at 90 ◦C. The Zn/CaO nanoparticles were recyclable for up to six reaction cycles and showed complete conversion even at room temperature. The amidation reaction of natural triglycerides was found to follow the pseudo-first-order kinetic model, and the first-order rate constant was calculated as 0.171 min−<sup>1</sup> for jatropha oil aminolysis. The activation energy (*E*a) and pre-exponential factor (*A*) for the same reaction were found to be 47.8 kJ mol−<sup>1</sup> and 4.75 × 10<sup>8</sup> min−1, respectively.

**Keywords:** nanospheroids; zinc-doped CaO; natural triglycerides; aminolysis; heterogeneous catalyst; recyclability
