Ionic Liquids: Applications and Perspectives

Knoevenagel condensation catalyzed by a tertiary-amine functionalized polyacrylonitrile fiber

The reaction of 3-chloropropyl silica (SilprCl) with 1,8-diazabicyclo[540]undec-7-ene (DBU) in dry acetone affords silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a new silica-supported ionic liquid catalyst Afterward, (SB-DBU)Cl is used for the efficient synthesis of 4H-benzo[b]pyran derivatives via the one-pot, three-component reaction of carbonyl compounds (cyclohexane-1,3-dione, 5,5-dimethylcyclohexane-1,3-dione or 3-methyl-1-phenyl-2-pyrazolin-5-one) with aromatic aldehydes and alkylmalonates Moreover, some novel bis(benzo[b]pyran)s and a broad range of structurally diverse spiro-pyrans containing oxindole and/or quinoxaline moiety in their structures are synthesized using (SB-DBU)Cl The catalyst is recycled and reused fifteen times with unchanged yield

Silica-bonded 5-n-propyl-octahydro-pyrimido[1,2-a]azepinium chloride (SB-DBU)Cl as a highly efficient, heterogeneous and recyclable silica-supported ionic liquid catalyst for the synthesis of benzo[b]pyran, bis(benzo[b]pyran) and spiro-pyran derivatives

Four novel basic ionic liquids (ILs), based on 1,4-diazobicyclo[2.2.2]octane (DABCO) and 3-chloro-1,2-propanediol, have been introduced as catalysts for Knoevenagel condensation. These catalysts are applicable to a wide range of aromatic/heteroaromatic aldehydes with α-aromatic (heteroaromatic or polyaromatic)-substituted methylene compounds in water at room temperature, and they afford the products in excellent yields within short times. These reactions are operationally simple, and the desired products can be separated directly from the reaction mixture without further purification. A possible reaction mechanism was proposed, and the relevant evidence was given. In addition, the ionic liquids used can be regenerated and recycled several times without significant loss of activity. Furthermore, the novel ILs could be efficiently used in a step of atorvastatin synthesis.

Novel DABCO Based Ionic Liquids: Green and Efficient Catalysts with Dual Catalytic Roles for Aqueous Knoevenagel Condensation

A mild, efficient, and environmentally benign protocol for the synthesis of tetrahydrobenzo[b]pyran derivatives in the presence of readily accessible, biodegradable, and choline hydroxide based ionic liquid as catalyst has been established. The key features of the reported methodology include good to excellent yields of desired products, simple work-up procedure and good recyclability of catalysts, which may be a practical alternative to the existing conventional processes for the preparation of 4-H pyrans to cater to the requirements of academia as well as industry.

https://www.mdpi.com/1422-0067/15/4/6897/pdf

An environmentally benign protocol for aqueous synthesis of tetrahydrobenzo[b]pyrans catalyzed by cost-effective ionic liquid

An efficient, clean and facile protocol for the Knoevenagel condensation of aromatic aldehydes with active methylene compounds catalysed by task specific ionic liquid 1,8-diazabicyclo[5.4.0]-undec-...

Le-Le Wang

Papers

Green and efficient Knoevenagel condensation catalysed by a DBU based ionic liquid in water

Green and Efficient Knoevenagel Condensation Catalyzed by a DBU Based Ionic Liquid in Water.