Organocatalytic Synthesis of (Hetero)arylidene Malononitriles Using a More Sustainable, Greener, and Scalable Strategy

Title:Organocatalytic Synthesis of (Hetero)arylidene Malononitriles Using a More Sustainable, Greener, and Scalable Strategy

Volume: 21 Issue: 5

Author(s): Suzaimi Johari, Mohd Rafie Johan and Nader Ghaffari Khaligh*

Affiliation:

• Nanotechnology and Catalysis Research Center, Institute for Advanced Studies (IAS), University of Malaya, 50603, Kuala Lumpur, Malaysia

Keywords: Sustainable chemistry, knoevenagel condensation, homogeneous catalysis, environmental protection, waste prevention, malononitrile analogs, β-cell protective activities, nitrogen-based organocatalysts.

Abstract:

Aim and Objective: The establishment of a green and sustainable Knoevenagel condensation reaction in organic chemistry is still crucial. This work aimed to provide a newly developed metal-free and halogen-free catalytic methodology for the synthesis of CS and (hetero-) arylidene malononitriles in the laboratory and industrial scale. The Knoevenagel condensation reaction of various carbonyl groups with malononitrile was investigated in ethanol, an ecofriendly medium, in the presence of seven nitrogen-based organocatalysts.

Materials and Methods: A comparative study was conducted using two as-obtained and four commercially available nitrogen-based organocatalysts in Knoevenagel condensation reactions. The synthesis of CS gas (2-chlorobenzylidene malononitrile) using a closed catalytic system was optimized based on their efficiency and greener approach.

Results: The conversion of 100% and excellent yields were obtained in a short time. The products could be crystallized directly from the reaction mixture. After separating pure products, the residue solution was employed directly in the next run without any concentration, activation, purification, or separation. Furthermore, the synthesis of 2-chlorobenzylidenemahmonitrile (CS) was carried out on a large scale using imidazole as a selected nitrogen-based catalyst, afforded crystalline products with 95 ± 2% yield in five consecutive runs.

Conclusion: Energy efficiency, cost saving, greener conditions, using only 5 mol% of organocatalyst, high recyclability of catalyst, prevention of waste, recycling extractant by a rotary evaporator for non-crystallized products, demonstrated the potential commercial production of CS using imidazole in ethanol as an efficient and highly recyclable catalytic system.

Cite this article as:

Johari Suzaimi, Rafie Johan Mohd and Ghaffari Khaligh Nader*, Organocatalytic Synthesis of (Hetero)arylidene Malononitriles Using a More Sustainable, Greener, and Scalable Strategy, Current Organic Synthesis 2024; 21 (5) . https://dx.doi.org/10.2174/0115701794268766231108110816