LABORATORY EXPERIMENT pubs.acs.org/jchemeduc
SIPCAn (Separation, Isolation, Purification, Characterization, and Analysis): A One-Term, Integrated Project for the Undergraduate Organic Laboratory Matthew R. Dintzner,* Charles R. Kinzie, Kimberly A. Pulkrabek, and Anthony F. Arena Department of Chemistry, DePaul University, Chicago, Illinois 60614, United States
bS Supporting Information ABSTRACT: SIPCAn, an acronym for separation, isolation, purification, characterization, and analysis, is presented as a one-term, integrated project for the first-term undergraduate organic laboratory course. Students are assigned two mixtures of unknown organic compounds—a mixture of two liquid compounds and a mixture of two solid compounds—at the beginning of the term, with the overall objectives to separate the mixtures, and isolate, purify, characterize, analyze, and ultimately identify the four unknown compounds. Through the SIPCAn project, students learn many of the fundamental operations and techniques of the undergraduate organic laboratory, including simple distillation, liquid liquid extraction, recrystallization, melting and boiling point range determination, spectral analysis, and spectral interpretation. KEYWORDS: Second-Year Undergraduate, Curriculum, Laboratory Instruction, Organic Chemistry, IR Spectroscopy, Mass Spectrometry, NMR Spectroscopy, Qualitative Analysis, Separation Science, Spectroscopy
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the organic chemistry laboratory in a more meaningful and contextual way than is presented in modular-based experiments. All laboratory experiments and related writing assignments are posted online (Supporting Information) and Zubrick’s The Organic Chem Lab Survival Manual is used as a reference manual.10
umerous texts have been published for the undergraduate organic laboratory1 and new, innovative experiments and projects are continually developed and reported in the literature, including in this Journal.2 7 Although most experiments are sufficient and many others very good, we were interested in “getting back to basics” for our first-term organic laboratory students— treamlining the curriculum while also providing students with an authentic and more comprehensive project-based laboratory experience.8,9 The rationale was to expose students to the fundamental operations and techniques of the organic chemistry laboratory through a more meaningful, integrated experience than is offered by most existing publications, by challenging the students to isolate, purify, and identify the unknown components of two organic mixtures. Thus, an eight-week project was developed called “SIPCAn”. SIPCAn, an acronym for separation, isolation, purification, characterization, and analysis, is a project-based laboratory experience that introduces students to many of the fundamental operations and techniques of the organic laboratory, including simple distillation, liquid liquid extraction, filtration, recrystallization, melting- and boiling-point range determinations, and spectral analysis and interpretation. Learning occurs through the process of separating two mixtures of unknown organic compounds—a mixture of two liquids and a mixture of two solids—and isolating, purifying, characterizing, and analyzing the components, with the ultimate goal of identifying the four unknown compounds through spectral analysis and interpretation. Although this project is simple in design and incorporates traditional experiments and methodologies, it does so in an integrated fashion and with a well-established end-goal for the students: identification of four unknown compounds. This approach affords students the opportunity to learn the fundamental techniques of Copyright r 2011 American Chemical Society and Division of Chemical Education, Inc.
’ EXPERIMENTS At the beginning of the 10-week term, students are given two coded vials containing separate mixtures of unknown organic compounds—one a mixture of two miscible liquids and the other a mixture of two solids. The liquid mixture consists of a lowboiling liquid (LBL) and a high-boiling liquid (HBL); the difference in boiling points is greater than 25 °C, such that the two components are separated (as well as isolated and purified) by a simple distillation (Scheme 1A). The liquids are characterized by determining their densities and boiling point ranges. The solid mixture consists of a carboxylic acid (RCO2H) and a “neutral” organic compound (RZ). These two components are dissolved in methylene chloride and separated by an acid base and liquid liquid extraction (Scheme 1B). The isolated solids are purified by recrystallization and characterized by determining their melting points. Students spend the next several weeks learning about and practicing spectral interpretation (MS, IR, NMR) through a series of “dry labs”, while also analyzing each of their unknown compounds and interpreting the spectra. By the end of the term, students identify each of their compounds. Throughout the project, students complete short writing assignments that lead to a mid-term progress report and one comprehensive Published: August 18, 2011 1434
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Journal of Chemical Education
LABORATORY EXPERIMENT
Scheme 1. “SIPCAn” of (A) the Liquid Mixture and (B) the Solid Mixture
Table 1. Project Schedule Lab
Experiment or Activity
1
Separation, Isolation, and Purification of Liquids by Simple Distillation
2
Characterization of Liquids by Density and Boiling-point Measurements
3 4
Separation and Isolation of Solids by Liquid Liquid Extraction Purification of Solids by Recrystallization and Characterization by Melting-point Measurements Midterm Progress Report (due at the beginning of lab 5)
5
Mass Spectrometry Dry Lab and MS Analysis
6
Infrared Spectroscopy Dry Lab and IR Analysis
7
1
8
13
H NMR Spectroscopy Dry Lab and 1H NMR Analysis C NMR Spectroscopy Dry Lab and Data Consultation
Final Laboratory Report (due at the end of the term)
final laboratory report in the style of the Journal of Organic Chemistry, complete with abstract, introduction, results (with tables and figures), discussion, experimental, and reference sections.
’ HAZARDS General laboratory safety procedures, including wearing safety goggles and gloves, must be followed at all times. All organic chemicals involved in these experiments are considered hazardous and direct physical contact with them should be avoided. All wet-laboratory experiments must be performed in a fume hood and wearing a laboratory coat or apron is advised. All chemicals
involved in these experiments are considered hazardous and direct physical contact with them should be avoided.
’ DISCUSSION This project is readily adaptable for any first-term undergraduate organic laboratory course. The choice of unknown compounds that comprise each mixture, as well as the order in which to conduct the experiments, is flexible; the system used at this institution is outlined in Table 1. Mixtures of liquids that are readily separated by simple distillation and are well resolved spectroscopically are typically used. For the solid mixtures, compounds that are readily separable by acid base and liquid liquid 1435
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Journal of Chemical Education extraction, easily purified by recrystallization, and well-resolved spectroscopically are used. The list of the possible unknowns is not provided to the students, though this information could be provided if the instructor feels it is helpful. The dry labs in the latter four weeks of the schedule consist of some lecture and discussion on the theory and practice of each of the instrumental techniques, followed by small-group problemsolving (spectral interpretation) exercises, concurrent with sample preparation and data acquisition. Ideally, the students should get hands-on experience with data collection on the analytical instrumentation (GC MS, IR, NMR) for some or all of their samples. However, if one or more of the instruments is not available or if the class size is too large for each student to collect a full set of data for each of their four samples, spectra of the unknown compounds may be provided to the students. Full data sets are posted for each unknown compound for students to compare with or supplement their own.
’ CONCLUSIONS SIPCAn represents an integrated project for the first term of an undergraduate organic chemistry laboratory that provides students with a contextual basis for learning the fundamental operations and techniques of the organic laboratory, including spectral analysis and interpretation. Students develop a sense of accomplishment upon completing the project and successfully identifying their unknown compounds. This allows for a more meaningful learning experience than often accompanies modularbased laboratory experiments, through which undergraduate students often fail to make essential connections from one lab to the next. We have also found that taking spectral interpretation out of the lecture portion of the class and covering it in the lab is very effective and “frees up” lecture time for other important topics.11,12 And, because much of the lecture content in the first term of organic chemistry is based on structure and physical properties (electronegativity and bond polarity, stereochemistry, functional groups, relative melting and boiling points, and solubilities), the SIPCAn project dovetails nicely with the content students are learning in the classroom.
LABORATORY EXPERIMENT
’ REFERENCES (1) In the most recent past we used: Lehman, J. W. Multiscale Operational Organic Chemistry: A Problem-Solving Approach to the Laboratory Course; Prentice Hall: Upper Saddle River, NJ, 2002. (2) Esteb, J. J.; McNulty, L. M.; Magers, J.; Morgan, P.; Wilson, A. M. J. Chem. Educ. 2010, 87, 1074. (3) Kennedy, B. J. J. Chem. Educ. 2008, 85, 393. (4) Alonso, D. E.; Warren, S. E. J. Chem. Educ. 2005, 82, 1385. (5) Green, W. J.; Elliot, C. J. Chem. Educ. 2004, 81, 239. (6) Herman, C. J. Chem. Educ. 1998, 75, 70. (7) Pienta, N. J.; Regitz, C.; Richards, J.; Sorrell, T. N. J. Chem. Educ. 1993, 70, 841. (8) Horowitz, G. J. Chem. Educ. 2007, 84, 346. (9) Mohrig, J. R. J. Chem. Educ. 2004, 81, 1083. (10) Zubrick, J. W. The Organic Chem Lab Survival Manual: A Student’s Guide to Techniques, 7th ed.; John Wiley & Sons, Inc.: Hoboken, NJ, 2008. (11) Alexander, C. W.; Asleson, G. L; Beam, C. F.; Doig, M. T.; Heldrich, F. J.; Studer-Martinez, S. J. Chem. Educ. 1999, 76, 1297. (12) Alexander, C. W.; Asleson, G. L.; Doig, M. T.; Heldrich, F. J. J. Chem. Educ. 1999, 76, 1294.
’ ASSOCIATED CONTENT
bS
Supporting Information Detailed instructions for the students and notes for instructors This material is available via the Internet at http://pubs.acs.org.
’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ ACKNOWLEDGMENT We thank the National Science Foundation CCLI A&I program (Grant No. DUE-0310624) for support in purchasing our Bruker Avance 300 MHz NMR spectrometer and DePaul University’s College of Liberal Arts & Sciences for funding and support of this work. The following DePaul undergraduate students are acknowledged for their participation and contributions: Stephanie Reeve, Barrett Unger, and Mark Aparece. 1436
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