Experiments illustrating techniques in synthetic inorganic chemistry and instrumental methods of analysis. Required for chemistry majors. Taught in the first half of the semester.
Freshmen may take the course with permission from instructor.

Prereq-CHEM 121 AND 122, 151 AND 152 or permission of intsructor

BH Rm. 280 01:00 PM - 5:00 PM Instructor: Andrew R. Barron

Introductory Laboratory Module



Andrew R. Barron


Butcher Hall 410, Ext. 5610

Email Address:

Office Hours by Appointment

Teaching Assistants:

Chris Edwards, BH410, ext. 3456,

Jake Ciszek, Room #GRB 213E,


The course grade is based upon the performance in the laboratory. This includes attendance (10%), preparation (10%), actual experimental skills developed (10%), results (20%) and the laboratory notebook (50%). You will work in pairs, but you should each keep a completely independent notebook. In addition, I will rely heavily on the opinions of the teaching assistants and my own observations of your work in order to assess your progress in the course. Your lab notebooks will be due by 5 PM, Friday, October 29; late notebooks will be penalized 3% per weekday late. It is recommended that you keep your lab notebook in your lab desk drawer to prevent loss.


You must at all times were safety glasses and you must follow reasonable safety precautions when working in the lab!!! Failure to abide by the safety regulations could get you kicked out of the lab. This is an extremely serious issue with dire consequences to health and safety of yourself and your colleagues. Wearing a lab coat or apron is recommended but not required. Specific safety precautions concerning the use of hazardous chemicals and operation of scientific equipment will be indicated whether by myself or by one of the teaching assistants. These procedures must be followed. If you have any doubts about the safety of something you are about to do, ask first!!! We will be most happy to answer your questions. Finally, and very importantly, at least one T.A. or myself must be physically present at all times for you to work in the lab.

If you have a documented disability that will impact your work in this class, please contact me to discuss your needs. Additionally, you will need to register with the Disability Support Services Office in the Ley Student Center.

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Introductory Laboratory Module
Laboratory Notebooks
Your laboratory notebook should be a clear and accurate record of your experiments and calculations as they happen. Thus, when you are done with an experiment and all of the chemicals used have been washed away, and all the apparati taken down, the notebook will serve as an infallible "memory" of what happened and how. This is especially true for thesis work where some time may elapse before results are written up for the thesis or publication. Industrial standards for keeping notebooks are rigorous, due to patent and other legal concerns, so that all entries may need to be witnessed, dated and signed. The following guidelines will be used in this course:
1. Use a durable, sewn notebook, preferably cloth bound.
2. Always record data in permanent ink.
3. Do not record any data on scrap paper. Scrap paper used for this purpose will be taken up, and your data will be lost. Record all data directly into your notebook and date. Quantities including the raw measurements should be included.
4. Cross through mistakes in such a manner so that they may still be read.
5. Include your name, section number, desk number, course title, semester date, college affiliation, and phone number in case your notebook is lost.
6. Number all pages in ink if this is not already done.
7. Include an updated table of contents at the beginning of the notebook. Blank space may be left at the beginning of the book for this purpose.
8. Leave no blank pages after the table of contents in your notebook.
9. The usual rules regarding significant figures should be observed. Never report more significant figures than warranted by the data.
10. Adopt a numbering scheme based on the date or notebook page for all samples and spectra. These numbers should appear on the sample/spectrum and when the sample/spectrum is mentioned in the notebook. ARB II 101 means the first sample on page 101 of A. R. Barron's second notebook. Also on the spectrum should be written the composition of the sample and the sample number.
11. A compressed scan or sketch of the spectrum placed directly in the notebook is a useful aid when the data are being reviewed.
12. The origin of solvents and reagents should be clearly stated.
13. Make it clear what apparatus was used. Whenever an unusual piece of equipment is first used, a sketch of it should be included.
14. If physical data are used, or if spectral comparisons are made with the literature, the reference should be recorded.
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Your notebook should contain:
1. Date. Be sure and date all entries in your notebook.
2. Title. The title should be as brief and as informative as possible. Titles should also be included for all drawings, charts, or graphs.
3. Introduction. The introduction should include the purpose of the experiment, descriptions of any chemical or physical processes expected to occur, and any known literature values or other data pertinent to the experiment. For chemical processes, include all pertinent balanced chemical equations.
4. Procedure. Reference the source of the experimental procedure you are following. Explicitly note any alterations you make in the procedure, and any differences in the outcome. Securely attach any pertinent handouts directly to the notebook page.
5. Observations. Include all numeric data obtained during the experiment. Label all numeric data clearly. Also include detailed descriptions of all pertinent physical or chemical processes that you observe.
6. Results. Label all numeric results clearly. Include, when appropriate, any final values obtained, standard deviations of measurements, and percent errors, when a theoretical result is available.
7. Conclusion. Did the experiment work? List possible sources of error, and explain whether they would lower or raise numeric results, if possible. If you have suggestions for improving the experimental procedure, you should include them as well.
More About Lab Write Ups for Your Notebook;
What do I want for the lab write up? The compiled report should be in the format listed in the above Laboratory Notebooks handout. It should be concise.
In the experimental section, the most important thing is to note details about things changed from the written procedure. You do not need to repeat the detailed experimental from the lab handout.
The results section is very important and should detail what happened (color changes, gas evolution, heat production, etc.). It should also list the analytical results (IR spectra, NMR spectra, melting points, etc.). It will probably be the longest section.
The discussion section is your chance to shine. Here you should describe problems you had with the synthesis, if any, and ways the experiment might be done better. You get to interpret the spectroscopic and spectrometric data. Concentrate on the highlights of the techniques as we discussed them in class. You might wish to explain why a given compound is expected to be diamagnetic or paramagnetic. You might wish to note specific IR bands and what they might mean based on the structure of your compound, etc. What are possible sources of error? Of low yields? Of impure materials? What did you learn about porphyrins and metalloporphyrins, in general? Feel free to discuss the experiments with the other lab groups, but write your own discussion in your own words.

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Introductory Laboratory Module
Synthesis, Purification, and Structural Characterization
of Porphyrin and Metalloporphyrin Compounds
Abstract: p-methyltetraphenylporphyrin (Me4TPPH2) is a commonly studied ligand which displays similar characteristics to the porphyrin ligands present in hemoglobin and other human metalloproteins. In this project, Me4TPPH2 is synthesized and purified by column chromatography. After synthesis of the porphyrin molecule, you will metallate this unique ligand's center with zinc(II), one of the metals commonly found associated with porphyrins in humans. Each group will prepare a different iron(III) complex, some of which have never been synthesized previously and none of which have been structurally characterized.
What you learn: You will learn how porphyrins form synthetically. Wet chemical techniques learned include distillation, reflux reactions, mixed-solvent extraction, and purification by column chromatography and recrystallization. Next, an introduction to Infrared (IR) spectroscopy, Mass Spectrometry (MS), Nuclear Magnetic Resonance (NMR) spectroscopy and the magnetic properties of materials (diamagnetism/ paramagnetism) will allow for the structural and electronic characterization of the porphyrin and metalloporphyrin molecules using modern research methods. Finally, you will learn how to prepare and isolate a new compound.
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Coordination compounds are extremely important in biological systems. A classic example is hemoglobin which uses an iron-centered macrocyclic ligand to carry oxygen reversibly from the lungs to other parts of the body. The functioning of hemoglobin is a delicate balance of structure and environment as the iron compound is expected to bind well to oxygen in an oxygen-rich environment and release it in an oxygen-poor one. In this experiment we will synthesize p-methyl-tetraphenylporphyrin which is a macrocyclic ligand that is very similar to the ligand around the iron center in hemoglobin. The iron-ligand complex in hemoglobin is known as heme. p-methyltetraphenylporphyrin (Me4TPPH2) and heme are shown below for comparison purposes. As you might expect, (Me4TPPH2) is much easier to synthesize than the heme ligand and consequently it has been widely studied. While its iron complex is a reasonable model compound, it unfortunately does not have all the properties of heme. Other much more complex porphyrin systems have also been synthesized which attempt to more closely mimic the function of heme.
Many other transition metal species are found to be important in biological systems. There is a class of very important cluster molecules which function as electron-transport agents. These are often clusters of iron with sulfur ligands and may also contain molybdenum. Copper is important in cytochrome c oxidase. Vanadium has been found in certain algae. Cobalt is found in vitamin B12. These are just a few examples. Just as p-methyltetraphenylporphyrin has been used to model the hemoglobin system, chemists are seeking to make compounds which mimic the function of these biologically-active compounds. In many cases the protein portion of the active molecules is so complex that model compounds may be the only way that a clearer picture of what is happening in the biological system may be obtained.
p-methyltetraphenylporphyrin (Me4TPPH2)



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Synthesis of crude p-methyltetraphenylporphyrin (p-Me4TPPH2)
Heat 350 mL of propionic acid to reflux in a 500 mL roundbottom flask using a heating mantle, a stirrer, and a reflux condenser. Add freshly distilled pyrrole (6.0 mL) and p-tolualdehyde (11mL) to the refluxing acid, making the final solution approximately 0.25 M in each reagent. After refluxing for 30 min., cool the solution to room temperature and collect the purple crystalline product by vacuum filtration. Wash the filter cake with methanol to remove excess propionic acid. The solid product contains about 3% tetraphenylchlorin (TPCH2) an undesired by-product. Calculate the yield based on pyrrole.
Purification of p-MeTPPH2
Prepare an alumina column (6.5 cm diameter) by filling it 12 cm high with a dense slurry of chloroform and activated neutral alumina. Allow the alumina to settle evenly while draining excess solvent. Add a solution with 350 mg of crude porphyrin (about 1/2 your sample) dissolved in 60 mL hot chloroform to the column and elute with fresh chloroform. Me4TTPH2 will elute first as a thick purple band, and TPCH2 will elute second as a minor green band. Collect the purple band and take it to dryness under reduced pressure. Collect the purple crystalline product. Recrystallize the solid product from chloroform. Calculate the percent yield based on Me4TPPH2. Determine if the material is diamagnetic or paramagnetic.
Preparation of [ZnII(Me4TPP)]
Dissolve 250 mg of pure Me4TPPH2 in 200 mL of chloroform using a 500 mL roundbottom flask. Bring the solution to reflux using a heating mantle, stirrer, and reflux condenser. Add an excess of zinc acetate (1.0 g) dissolved in a minimum of hot methanol. Reflux the solution for 2 hours and then remove all the solvent under reduced pressure. Dissolve the resulting solid in a minimum of CH2Cl2 and filter to remove excess zinc acetate. Discard the filter cake. Remove the solvent under reduced pressure and redissolve the resulting solid in a minimum amount of hot chloroform (approx. 50 mL). Purify on a silica column as above, eluting with chloroform. The [ZnII(Me4TPP)] band should be reddish purple and should elute first. Recrystallize the solid product as above. Calculate the percent yield based on Me4TPPH2. Determine if the material is diamagnetic or paramagnetic.

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Introductory Laboratory Module
Synthesis and Characterization of Unknown Iron Porphyrin Compounds


Abstract: In this project you will prepare a new (previously unknown) iron(III) porphyrin compound. Each team will prepare a compound with a different substituent. After the synthesis of these new compounds you will determine its structure by IR spectroscopy, magnetic properties and (if you can obtain suitable crystals) X-ray crystallography. The results from all the groups will be combined to allow comparison of these new compounds. If the results warrant, the new compounds will be written-up for publication in a peer-reviewed chemistry journal.
What you learn: You will learn to prepare and characterize a previously unknown compound. You will learn to adapt your synthetic and purification methods to an unknown compound. The processes and methods that are required are the basis for scientific research.
 Nature's elaboration of the fundamental iron porphyrin structure has resulted in a multiplicity of functions for the hemeproteins. Thus, oxygen transport in the hemeglobins, electron transfer in cytochromes c, and oxygen redox chemistry in the cytochromes P450 and peroxidases are all achieved at an iron heme active site. In understanding the heme site a number of model compounds have been investigated including iron(III) porphyrin complexes possessing an oxygen donor ligand in the axial position. The simplest class of these compounds include the carboxylato iron(III) porhyrins, (por)Fe(O2CR), where R = an organic group. A number of these compounds have been reported (H. Oumous, C. Lecomite, J. Protas, P. Cocolios, and R. Guilard, Polyhedron, 1984, 3, 651-659, and S. A. Moy, J. A. Gonzalez, and L. J. Wilson, Acta Cryst., 1995, C51, 1490-1494), however, only two have been structurally characterized.


Preparation of [FeIII(Me4TPP)Cl]
 Dissolve 250 mg of pure Me4TPPH2 in 200 mL DMF using a 500 mL roundbottom flask. Add a few small boiling chips, and an excess of FeIIICl3*6H2O (1.0 g) dissolved in a minimum amount of hot methanol. Heat the solution to 145 °C using a hot plate and sandbath apparatus, a thermometer, and a reflux condenser. After heating for 3 hours, remove the roundbottom flask from the sandbath (caution: flask will be very hot) and allow to cool to under 60 °C. Concentrate the solution to 100 mL under reduced presure and slowly add 150 mL deionized water to precipitate a crude sample of [FeIII(Me4TPP)Cl]. Filter and wash with cold water, then air dry on the filter paper.
Preparation of [FeIII(Me4TPP)]2(m-O)
Weigh the dried sample of [FeIII(Me4TPP)Cl] and the filter paper. Add the sample and filter paper to 75 mL of CH2Cl2. The of [FeIII(Me4TPP)Cl] will dissolve and the filter paper may be removed and dried. Re-weighing the filter paper will allow you to calculate the yield of [FeIII(Me4TPP)Cl]. To the CH2Cl2 solution of [FeIII(Me4TPP)Cl] add an equal volume of 1 M perchloric acid. Stir for 1 h. The organic layer is separated in a separation funnel and washed with distilled water. (N.B. Make sure you retain both layers, just in case you use the wrong one!) Separate the CH2Cl2 solution of [FeIII(Me4TPP) ]2(m-O) and add 150 mL of heptane to precipitate the red microcystalline product. Filter and air dry on the filter paper. Determine if the material is diamagnetic or paramagnetic.
Preparation of [FeIII(Me4TPP)(O2CR)]
Weigh a sample of [FeIII(Me4TPP) ]2(m-O) into a round bottom flask. Add an excess of the carboxylic acid you have chosen. It is usual to add at least a 10-fold excess. If the carboxylic acid is a liquid, heat the mixture to reflux for 20 min. Then cool to room temperature. Check with TLC to make sure all the [FeIII(Me4TPP) ]2(m-O) has reacted. If it has not, continue heating the solution for another 20 min. Once all the [FeIII(Me4TPP) ]2(m-O) has reacted, place the sample in the fume hood to evaporate the excess acid. If the carboxylic acid is a solid, then heat the mixture until the carboxylic acid melts (see the Aldrich™ catalogue for the melting point ) and continue to heat for 20 min. Check with TLC to make sure all the [FeIII(Me4TPP) ]2(m-O) has reacted. If it has not, continue heating the solution for another 20 min. Once all the [FeIII(Me4TPP) ]2(m-O) has reacted wash the sample with 50 mL of hot isopropyl ether and recrystallize the solid from a minimum amount of toluene. Determine if the material is diamagnetic or paramagnetic. Caution: Some of the carboxylic acids are very smelly! Use gloves and handle in the fume hoods at all times.

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