Anthraquinone Dyes: A Synthetic and Chemical Characterization Protocol for an Industrial Chemistry Laboratory Course

Younis Baqi*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

A fast, operationally simple, and reproducible synthetic protocol for anthraquinone dyes (AQDs), suitable for upper-division undergraduate industrial and organic chemistry laboratory courses, has been developed. This experiment is composed of three stages; the first step deals with the synthesis of AQDs, followed by a purification step, and finally a chemical characterization of the pure dyes. This can be completed within 2-3 laboratory sessions (3 h each). Synthesis is performed via Ullmann coupling reaction starting from inexpensive commercially available materials, 1-amino-4-bromoanthraquinone-2-sulfonic acid sodium salt (bromaminic acid), amine/aniline derivatives, phosphate buffer (pH 6-7), and a catalytic amount of elemental copper (Cu0) under microwave irradiation at 120 °C within a short reaction time (2-20 min). The crude blue dyes are purified by extraction with dichloromethane followed by column chromatography using reversed phase C-18 material. The clear difference in colors between starting material (orange and red), byproduct (dark red), and products (blue) allows for great ease in visual monitoring of the chromatographic separation. The target AQDs are fully characterized by spectroscopic methods.

Original languageEnglish
Pages (from-to)1441-1447
Number of pages7
JournalJournal of Chemical Education
Volume99
Issue number3
DOIs
Publication statusPublished - Mar 8 2022

Keywords

  • Dyes/Pigments
  • HPLC
  • Hands-On Learning/Manipulatives
  • Industrial Chemistry
  • Laboratory Instruction
  • Mass Spectrometry
  • NMR Spectroscopy
  • Organic Chemistry
  • UV-Vis Spectroscopy
  • Upper-Division Undergraduate

ASJC Scopus subject areas

  • Chemistry(all)
  • Education

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