Undergraduate Organic Chemistry Laboratory Experiments

Reactions on Supported Reagents



This posting is a cooperative effort between the University of Wyoming and Dartmouth College. The experiments were developed in the Chemistry Department at the University of Wyoming under the direction of Dr. David A. Nelson and will be user tested by Dr. James J. Worman of Rochester Institute of Technology. Posting was accomplished through the guidance and cooperation of Dr. Joseph BelBruno of the Chemistry Department at Dartmouth. The written descriptions are designed to contain only minimal experimental details. This was done to allow the instructor and the student to participate more fully in the development of the experiment. Theory is not included in the write-up and need to be supplemented from an organic laboratory manual or text.

For a similar site which lists experiments in all areas of chemistry see ChemJOULE, the Chemistry Journal Of Undergraduate Laboratory Experiments


Introduction to Supported Reagents Organic Experiments

Background: This project was initiated with support from the National Science Foundation as a Leadership in Laboratory Development grant under the Instrumentation for Laboratory Instuction program (ILI-LLD).

A. The object of this project was to develop a new methodology for carrying out experiments in the undergraduate organic chemistry laboratory using supported reagents and catalysts. A major goal was to offer an alternative to the apparatus-intensive technique type of laboratory. Some major features of this approach are:

B. The new methodology was directed primarily toward the large enrollment, service type of laboratory that could come under threat of elimination due to pressures related to costs, safety, or pedagogical inappropriateness. However, as the project developed, additional applications have become apparent. Some of these are:

C. Some more specific areas that have been developed are:

Return to HomePage

© August 1997.


Lower costs:

The experiments have been developed using polypropylene devices that are marketed for solid phase extraction (SPE) procedures. These have been on the market for several years, and are available from a variety of suppliers. Altech Associates, Inc. of Deerfield, IL is a convenient source of SPE devices. Standard types of small scale laboratory glassware can be used for some supported reagent reactions, but the polypropylene devides have advantages in cost and convenience. One 8mL size resevoir with a frit which serves as a reaction vessel costs about $0.43, compared with a small standard taper flask, or reaction vial, at $8-$10 each. The polypropylene reservoirs are essentially unbreakable, and can be reused. A complete "kit" for running the procedures described here can be assembled for $25-$50 per student. A vacuum manifold for 12-24 students costs $500-$700. Only one of these would be necessary per lab, and usually can be purchased on a supplies budget. The procedures are written at the 10-100 mg level, and correspond with most small or "microscale" experiments. Solvent use is minimum. Most of the supports and many of the supported reagents and catalysts can be recycled or regenerated.

Return to Top


Reduced Hazards and Waste Minimization:

All of the procedures being developed will avoid the use of carcinogens and highly toxic materials. One major feature of the supporting of reagents is that certain hazards can be reduced in a practical sense. The vapor pressure of volatile and noxious reagents can be reduced. The use of a vacuum manifold can greatly reduce the amount of volatile solvents released into the laboratory. Since most of the supports can be reused or recycled they do not need to be listed as hazardous waste. Regeneration methods can be written into procedures. This has not yet been done with most of the experiments described here, but we intend to do more with this in the future. Users may want to develop methods best suited to their own local situation. In any case, it must be remembered that supporting a toxic or carcinogenic material does not change its hazard in terms of waste disposal. Polymer supported hydrogen chromate is still a carcinogen. The cyanide form of an anion exchange resin is still a highly toxic material.

Return to Top


Emphasis on Principles:

This methodology for carrying out organic reactions is not intended to teach traditional organic laboratory techniques. Certainly some of the methods presented are important to professional chemists and should be considered for presentation to chemistry majors. (See B.1.) However, a major potential audience for this approach is the large enrollment non-major service organic course. The traditional apparatus-intensive, technique oriented, cookbook procedure laboratory, with emphasis on product yield and purity, and usually not correlated with the lecture, has been criticized as not being the most appropriate for this group of students. With the conviction that laboratory is still a vital part of teaching organic chemistry, methods were developed that could allow a reasonably varied and sophisticated group of reactions to be presented to students. They give an opportunity to involve the student in understanding the reaction principles, the major conditions necessary for the reaction to take place, and the outcome of the reaction. The use of spectroscopic and other instrumental analyical methods are encouraged.

The initial experiments being developed are representative of basic organic processes, and would correlate best with a mechanistic course approach. Areas addressed to date include the following:

Return to Home Page


SPE tubes:

The "equipment" is formulated from devices currently being marketed under the category of "solid phase extraction" (SPE). These are available from several sources and come in various sizes. We have used primarily 8.0mL sized items from Alltech Associates, Inc. Similar items are available from Millipore, Burdick and Jackson, Supelco, J.T. Baker, and most chromatographic supply houses. SPE "tubes" or "reservoirs" are essentially polypropylene syringe barrels. Frits made of 20 micron porous polyethylene are available to fit into the tubes. A frit is pressed into the bottom of a tube and the desired amount of supported material added. A second frit can be placed on top to hold the support, but this is not always necessary or desireable. In general, the frits and tubes can be reused several times.

Other useful items are adapters to stack two or more tubes in series, and caps for the ends of the tubes. With some supports, particularly ion exchange resins, reactants in solution can flow through by gravity, but in other cases, usually when silica, alumina, or clays are used, it is necessary to be able to apply a vacuum. Commercial vacuum manifolds are available and convenient, but expensive. A filter flask or side arm test tube fitted with a syringe needle through a stopper will serve the purpose.



Return to Orgo Homepage


Experiment #1 Aldol Type Condensations on Supported Reagents
Experiment #2 Separation of Benzoic Acid, Ethyl p-aminobenzoate, and Benzoin
Experiment #3 Oxidation of 9-Fluorenol to 9-Fluorenone
Experiment #4 Reduction of 9-Fluorenone to 9-Fluorenol
Experiment #5 Isolation of Caffeine from Coffee

SPE Tubes and other Equipment

Procedures for Microwave Activated Dry Media Reactions

General Information

Experiment #1

Experiment #2

 


For additional details regarding the sample experiment contact David Nelson. Additional details on the project to create this directory of experiments may be obtained from David Nelson or from James Worman





If you have any comments or suggestions, please let us know via this on line form.


This site is maintained by David H. Blank.

©June 1997, Department of Chemistry, University Of Wyoming. All rights reserved.

DISCLAIMER:

These experiments are designed to be used in college and university level chemistry laboratory courses, and assume the availability of routine supplies, equipment, and instrumentation usually associated with organic chemistry laboratory courses, as well as an appropriate modern level of supervision, safety training, personal protective equipment, and other safety facilities. Any users of these procedures assume all responsibility for the safe handling of hazardous chemicals and procedures. In any event the authors, webmasters, The University of Wyoming , Rochester Institute of Technology, or Dartmouth College shall not be liable for incidental or consequential damages in connection with, or arising out of, the furnishing, performance, or use of these procedures.