Abstract
ABSTRACTA two-step synthetic sequence was developed for the undergraduate organic chemistry laboratory using vanillin as the starting material. The multi-step synthesis was designed to replace two traditional experiments teaching electrophilic aromatic substitution and carbon–carbon bond forming chemistries with greener transformations. Vanillin is iodinated using Oxone® and potassium iodide in refluxing water, and students are tasked with determining the position of aromatic substitution using 1H NMR spectroscopy. The tan, shiny, pleasant-smelling iodovanillin is subsequently used in an aqueous Suzuki-Miyaura reaction with para-methylphenylboronic acid; strategically chosen to afford a second instructive 1H NMR spectrum. Both conventional heating and microwave conditions can be employed for the palladium-catalyzed reaction. This synthetic sequence, successfully performed over multiple semesters by hundreds of students, models green chemistry principles through the use of a potentially renewable feedstock and safer reagents, the choice of water as a safer reaction solvent, and the employment of a catalytic reaction. Additionally, the sequence minimizes waste in teaching labs through use of an intermediate product.
Highlights
Continuing with our efforts to revise the organic chemistry laboratory curriculum to demonstrate modern green synthetic methods, we sought to replace our program’s decades-old electrophilic aromatic substitution (EAS) reaction and Grignard synthesis with more
The described iodination of vanillin experiment was successfully performed in our organic chemistry laboratory course over nine semesters by approximately 2500 students
Students were enthused by the opportunity to use vanillin, a familiar substance ubiquitously found in flavors and fragrances, in their organic chemistry laboratory setting
Summary
Continuing with our efforts to revise the organic chemistry laboratory curriculum to demonstrate modern green synthetic methods, we sought to replace our program’s decades-old electrophilic aromatic substitution (EAS) reaction and Grignard synthesis with more. Of special note is a teaching laboratory experiment reported by Doxsee and Hutchison [16] wherein a sodium hypochlorite solution (NaOCl) (bleach) was used in combination with NaI in ethanol/water These conditions most likely follow the same mechanistic pathway as the Oxone® procedure. Upon successful implementation of the Oxone®/KI iodination procedure in our teaching laboratories over several semesters, we sought to use the 5-iodovanillin product as a substrate in a subsequent reaction. We were interested in exploring the Suzuki-Miyaura reaction, the cross-coupling of an aryl or vinyl halide with an aryl or vinyl boronic acid, as a modern topic increasingly taught in organic chemistry lecture and laboratory courses. Keesara and Parvathaneni reported synthesis of this product in their studies of an arylpiperazine ligated catalyst for the Suzuki-Miyaura reaction [25]
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.
