Sulfur and limonene are by-products of industrial processes and are readily available and inexpensive. Sulfur is produced in large quantities in the petroleum industry, and limonene can be obtained from peels of fruits process in the citrus industries. In this project, we designed a multi-week laboratory experience to investigate the properties of the polysulfide materials generated from the sulfur and limonene substrates’ direct reaction. The experience’s main objectives are introducing students to natural product isolation and characterization via simple laboratory techniques and utilizing the extracted chemicals to run reported reactions. Specifically, citrus fruits (i.e., lemons and oranges) were treated to isolate the peels’ essential oils via steam distillation. Once separated, the essential oils were characterized by measuring their physical properties (i.e., density, specific rotation via polarimetry), then reacting them with elemental sulfur at 150-170 °C for 60 min. The product of the reaction was a limonene-based polymeric material. The polymer characterization was based on its physical properties: its solubility in organic solvents and its specific rotation. For comparison studies, samples of (R)-limonene and (S)-limonene were also subjected to reactivity with sulfur to determine their properties. Laboratory procedures and experimental results will be presented and discussed in light of their future implementation in the organic chemistry laboratories at Sam Houston State University.

Limonene reactivity with elemental sulfur as an introduction to polymer chemistry and polarimetry in the organic chemistry laboratory

ACS Spring Meeting 2021

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