Reversed-Phase Separation and the Identification of Unknown Polar Compounds

TCE

The Chemical Educator

ISSN: 1430-4171 (electronic version)

Table of Contents

Abstract Volume 20 (2015) pp 95-98

Reversed-Phase Separation and the Identification of Unknown Polar Compounds

Kate J. Graham*, Aaron R. V. Koenig, Kiarah J. Ray, and Edward J. McIntee

Chemistry Department, College of Saint Benedict/Saint John’s University, 37 South College Avenue, St. Joseph, MN 56374, kgraham@csbsju.edu
Received March 10, 2015. Accepted April 13, 2015.

Published: 1 May 2015

Abstract. Reversed-Phase Chromatography is a standard technique for the separation of many natural compounds and is an extremely useful tool for a variety of industrial, food, law enforcement and medical applications. This manuscript describes an experiment for the separation of unknown polar compounds using inexpensive reversed-phase SPE C18 columns. Students perform a chromatographic separation on a sample of an unknown polar compound contaminated with benzophenone. Students then determine the identity of their compound with melting point, GC-MS, IR, ¹H and ¹³C NMR spectroscopy, and comment on the purity of the final sample. The use of unknowns increases students’ individual responsibility and prevents using a partner’s data analysis. This experiment was developed for use in a first year foundation laboratory but it would also be suitable for implementation in a sophomore organic chemistry laboratory.

Key Words: Laboratories and Demonstrations; organic chemistry; inquiry-based/discovery learning; chromatography

(*) Corresponding author. (E-mail: kgraham@csbsju.edu )

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Supporting Materials:

Instructor preparation notes with CAS numbers for chemicals, experimental procedures for students, student handouts, prelab quiz and a grading rubric. (216 KB)