Iodination of vanillin and subsequent Suzuki-Miyaura coupling: two-step synthetic sequence teaching green chemistry principles

James J. Palesch, Beau C. Gilles, Jared Chycota, Moriana K. Haj, Grant W. Fahnhorst, Jane E. Wissinger

Research output: Contribution to journalLetter

1 Scopus citations

Abstract

A 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.

Original languageEnglish (US)
Pages (from-to)117-126
Number of pages10
JournalGreen Chemistry Letters and Reviews
Volume12
Issue number2
DOIs
StatePublished - Apr 3 2019

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Keywords

  • NMR spectroscopy
  • Suzuki cross-coupling
  • Undergraduate teaching laboratories
  • aqueous reactions
  • electrophilic aromatic substitution
  • green curriculum

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