Abstract
Abstract Deep eutectic solvents (DESs) are successfully used as powerful and recyclable catalysts and solvents for the synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones (DHPMs). The acidity of DESs is the main factor that determines catalytic activity. DESs, based on p-toluene sulfonic acid (PTSA) and choline chloride (ChCl), exhibits the highest catalytic activity. ChCl/2PTSA is suitable for a vast variety of aromatic aldehydes with electron-donating and electron-withdrawing groups, different β-diketonates, and urea or thiourea to obtain the corresponding DHPMs. Furthermore, DESs can be recycled easily after synthesis. The reused DESs achieve catalytic efficiency six times without significant changes. This study will provide a new green catalyst and efficient process for the synthesis of DHPMs.
Highlights
The results showed that the concise control of the acidity of Deep eutectic solvents (DESs) can be modified by changing the hydrogen bond donors (HBDs) and hydrogen bond acceptors (HBAs)
One of the advantages of DESs is the simple control of its acidity, which can be achieved by selecting the appropriate HBDs
Choline chloride (ChCl) was chosen as the HBA, and p-toluenesulfonic acid (PTSA), trichloroacetic acid (TCA), monochloroacetic acid (MCA), propionic acid (PA), and ethylene glycol (EG) were chosen as HBDs
Summary
The development of new types of DESs catalysts with high efficiency is an important subject in the field of synthesis of DHPMs. In this work, some novel DESs with different acidities were designed, synthesized and applied as powerful and recyclable catalysts and solvents for synthesizing DHPMs. The reaction system based on DESs benefits from the benign reaction conditions, high catalytic activity, easy work-up procedures, feasible reusability and wide substrates tolerance. The above DESs were used as catalysts and solvents for the Biginelli reaction of benzaldehyde, ethyl acetoacetate and urea; this was selected as the model reaction to optimize the synthesis conditions Some important parameters, such as system temperature, reaction time, and amount of DESs, as well as the different kinds of aromatic aldehyde, were investigated.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
