CES (calcined eggshell)
Organic Chemistry International, Volume 2012 (2012),
doi:10.1155/2012/153159
CES as an Efficient Natural Catalyst for Synthesis of Schiff Bases under Solvent-Free Conditions: An Innovative Green Approach
Organic Research Laboratory, Department of Chemistry, Padmabhushan Dr. Vasantraodada Patil College, Sangli District, Tasgaon 416312, India
http://www.hindawi.com/journals/oci/2012/153159/61695452/
A mild and efficient method has been reported for the preparation of Schiff base ligands through the condensation reaction of various aromatic aldehydes with substituted aromatic amines in the presence of CES (calcined eggshell) as a heterogeneous catalyst under solvent-free conditions. The advantages of this ecofriendly, economic method are simplicity of the reaction procedure, moderate to good product yields, and very short reaction times.
Chicken eggshells were collected in bulk and cleaned thoroughly with distilled water. The broken shells are then boiled in water to remove any adhesion. After cleaning, eggshells are dried in oven at 80°C and crushed into fine powder using mortar and pestle. This raw eggshell powder was then calcinated at a heating rate of 2°C/min in Muffle furnace to 900°C and this temperature was maintained for 3 hrs. The thermal treatment had two parts: in the first 30 minutes. most of the organic materials were burnt out, whereas in the second part the eggshell get transformed into white soft powder which was denominated as CES.
http://www.hindawi.com/journals/oci/2012/153159/61695452/
