Instructor Evaluation of Peer-Developed Peer-Led Labs

Positive:

+ There were some real student success stories that would not have happened in the usual laboratory sequence. I felt like all of the student groups really made and effort to put together a quality lab.

+ Whether or not students completely understood the experiments they were developing, they did have an opportunity to think of laboratory from the perspective of the “creator” and/or “producer” as well as “consumer.”

+ I think that this was a meaningful group project. I think that, as a group, students were able to accomplish things that they would not have been able to do individually.

 

Neutral Commentary:

±Analysis of products tended to extend the time required to complete the lab reports because it took time to collect and distribute all of the data.

±Lab development is rather time consuming to do it right. Mistakes were made because not everything was thoroughly checked through before the lab handout went into press.

±There was still a pretty big element of instructor control. I wanted to be sure that the labs were comparable to each other and comparable to labs they would normally be doing.

 

Negative:

- I was surprised that there was not more “ownership” of the experiment by the group who was producing the lab the day that it was being performed by their peers. I will try to increase the involvement of the group who developed the lab next time.

- There was a little more difficultly in synching labs with course content.

- I need more skill if I am going to follow the “draft” method of evaluating student work. Students tend to view resubmitting drafts as simply correcting the specific errors that the instructor pointed out. I need to write a more detailed rubric for both the lab handouts and webpages. Maybe a better way to gauge participation of each member of the group too.

Week 13: Ugi Synthesis Collaborative Project

Crystallization:
This week we harvested crystals from those reactions that gave a precipitate and attempted to obtain a solid from those reactions that had not spontaneously formed a precipitate. The two reaction mixtures with 3,4,5-trihydroxybenzoic acid tended to form precipitates the most readily, but not all of them did. The two reaction mixtures with 2,4,6-trihydroxybenzoic acid precipitated very slowly with mostly brown solid. A couple of them had what looked like transparent crystals covered in brown syrup. Several of the vials were dried down with forced air to encourage crystallization. In some a solid was formed, in others a brown syrup resulted. We tried to find a solvent that would dissolve the brown impurities and not the Ugi product or dissolve the Ugi product and not the impurities. This game plan did not work so well. The best idea seemed to be to carefully clean the crystals with methanol in a vacuum filtration funnel. I suppose the best thing to do would be to those that didn’t form a precipitate another week, but that didn’t seem possible, since it’s the end of the semester and all. Is the Ugi reaction slow in forming products or are the products slow in precipitating from solution?

Analysis:
All of the Ugi reactants gave a GC trace. GC-FID analysis of the filtrate gave some non-reactant peaks. However, the Ugi product collected by filtration did not appear to “fly” in the GC. We did IR KBr windows with a few of the Ugi products. We have and archaic system of making the salt windows with a bolt and two screws so the quality of the windows and subsequent IRs is not too good. We do see carbonyl peak and a phenolic hydroxyl peak. The UV spectra of the products are generally useful in distinguishing between different products and seem somewhat different than the reagent UV spectra..

Barriers to Contributing to (& Benefiting From) Online Communities

For OChemOnline it is essential to increase the intersection between 1) People with internet skills able to perform simple internet tasks, 2) Organic Chemistry laboratory instructors and students, and 3) Individuals motivated to contribute to and benefit from an online community. Skills are important, but they do not seem to be the major obstacle. Everything you want to accomplish in life requires a certain learning curve. I think the 3^rd group is the most critical. What are barriers to participating in online communities (assuming the skills to navigate a wiki are learnable)?

1) Comfort level. There is a certain threshold to sharing personal information on the internet.

2) Potential embarrassment. Those who post ideas and information open themselves to criticism or worse.

3) Intellectual property issues. If I tell you what I know, I relinquish my proprietary knowledge that may lead to income generating activities, formal publication and/or a snobbish sense of self-importance.

4) Perceived benefits. Typically effort expended to do the busy-work necessary for online community is proportional to the perceived benefit.

5) Entertainment value. The internet is supposed to be entertaining. If it is not, we feel somewhat let down.

6) The natural distribution of the adoption of new things. Some people are early adopters, they will try anything just for the novelty of it. Others need to see that a certain “critical mass” of participation has been achieved before they jump in.

7) Encouragement. Community is about mutual encouragement. It is encouraging when someone responds to your participation. Encouragement is about evidence that my contribution matters to others.

Any more? This should really be a “top 10” list.

Week 12: The Ugi Synthesis Collaborative Project

The Ugi reactions are up and running.

The combinations we are investigating are:

students	Aldehyde	Amine	Carboxylic acid	isocyanide
8	3,4-dimethoxybenzaldehyde	methyl amine	3,4,5-trihydroxybenzoic acid ●monohydrate	p-toluenesulfonyl methyl isocyanide
5	3,4-dimethoxybenzaldehyde	methyl amine	2,4,6-trihydroxybenzoic acid ●monohydrate	p-toluenesulfonyl methyl isocyanide
5	3,5-dimethoxybenzaldehyde	methyl amine	3,4,5-trihydroxybenzoic acid ●monohydrate	p-toluenesulfonyl methyl isocyanide
5	3,5-dimethoxybenzaldehyde	methyl amine	2,4,6-trihydroxybenzoic acid ●monohydrate	p-toluenesulfonyl methyl isocyanide

 

The combinations with the gallic acid (3,4,5-trihydroxybenzoic acid) precipitated very quickly. I was a little alarmed about that so I instructed the Wednesday group to weigh out all their compounds first and then add them together sequentially as soon as the previous mixture was homogeneous. I noticed that in the Monday group sometimes students would take 10 minutes or more to locate the next reagent and weigh it out. As far as I can tell, that did not make much difference, but it is something to consider. We did not have any problems with solubility, other than a rather rapid onset of precipitation.

 

We doubled the amounts (1 mmole to 2 mmole) from what is typically done by the UsefulChem group. In my experience, it is always a good idea to give undergraduate students as much product as possible to play around with. With a group of students, anomalies always crop up. Some may be due simply to inattention (“human error” as my students report in their write-ups), others are more subtle and insidious. It is always a good idea to characterize all the reagents – they tend to pop up in student “products.” Its not hard to spot in the anomalous vials in our photos.

 

The second set of reagents corresponds to UsefulChem experiment 171H (Spreadsheet number: 171HV2B which have crystals for within 8-10 days.

Putting a Human Face on Electronic Social Networking

This week a number of electronic Social Networking chemists are traveling to New Orleans for the Spring 2008 American Chemical Society National Meeting. It seems ironic that eSocial Networkers perceive a need to promote their projects in a face-to-face Social Networking situation. I other words, no matter how prolific and how proficient you are at social networking you still need to be seen at the right meetings and talk to the right people. Is eSocial Networking simply an extension of f2fSocial Networking? If so, then the added challenges of technical skills, access to soft/hardware, human effort, and time pose considerable obstacles to the success of eSocial Networking. On the other hand, we are possibly experiencing a transition period where eSocial Networking eventually replaces f2fSocial Networking as a dominant social force. This is the message I get when I see my 8^th grade son spending hours in front of the computer screen. This is the scenario that we educators are struggling to keep up with as we try to extend our technical expertise and web savvy to keep up with changing student expectations. More likely, a dynamic equilibrium is being established with eSocial Networking becoming more and more adept at putting on to a human face. Eventually, human contact will become an extension of electronic relationships. Dedicated to my ecolleague, Jean-Claude Bradley.

Week 11: “Synthesis of Aromatic Esters”

Source(s): This lab was developed from a recent JCE article: Wade P.A.; Rutkowsky S.A.; King D.B. A simple combinatorial experiment based on Fischer esterification - An experiment suitable for the first-semester organic chemistry lab. J Chemical Education 2006, 83(6), 927-928. This, of course, is a version of the ever-popular “banana-oil” lab found in a multitude of laboratory manuals such as: Pavia D. L.; Lampman G. M.; Kriz G. S. “Introduction to Organic Laboratory Techniques: a contemporary approach” 1^st edition 1976 W. B. Saunders Company.

Changes to published procedure
In this lab we were aiming to synthesize three “novel” aromatic esters: propyl 4-methoxycinnamate, propyl 4-methylbenzoate, propyl 2-methylbenzoate.
These are novel in the sense, that there is currently no chemical information for these compounds in “chemspider” nor “emolecules” databases.
We added a large excess of 1-propanol to push the equilibrium towards the products.

Positive
+ Simple procedure, the emphasis was more on characterizing novel compounds.
+ The products smell okay – olfactory confirmation of a successful synthesis.

Neutral
± At first, I recommended too little alcohol and some unfortunate side reactions happened between the carboxylic acid and sulfuric acid.
± To my surprise, the products were liquids at room temperature. I was expecting some waxy solids.

Negative
- An additional purification step is needed. Vacuum distillation? Column chromatography?
– Our instruments and skills are pretty limited to do much characterization: I will have to outsource the MS and NMR data.

Inquiry & Extension ideas.
● A combinatorial scheme projects the synthesis of hundreds of novel esters from carboxylic acids and alcohols ordered from Aldrich.
● Milder conditions would make the use of secondary alcohols possible.

Week 11: “Vanillin Synthesis from 4-Hydroxybenzaldehyde”

Source(s): This lab was developed by a team of students from a recent JCE article: “Vanillin Synthesis from 4-Hydroxybenzaldehyde.” Douglass F. Taber, Shweta Patel, Travis M. Hambleton, and Emma E. Winkel, J. Chem. Educ. 2007, 84, 1158. An online version of the lab was available at http://valhalla.chem.udel.edu/vanillin.pdf

Changes to published procedure
We scaled up the procedure – Part I 0.5g 4-hydroxybenzaldehyde.The product from Part I (3-bromo-4-hydroxybenzaldehyde) was isolated by liquid-liquid separation and solvent evaporation.All of the product from Part I was used for Part II.We used boiling water baths to heat the reaction for Part II.
We did not do the column chromatography step. We performed a GC-FID of the products from both Part I and Part II.

Positive
+ A little more challenging procedure – a nice fit for late 2^nd semester.
+ The product smells nice – olfactory confirmation of a successful synthesis.

Neutral

± It is very difficult to distinguish between 4-hydroxybenzaldehyde, 3-bromo-4-hydroxybenzaldehyde, and vanillin by TLC.
± Our GC did not distinguish between 3-bromo-4-hydroxybenzaldehyde, and vanillin.

Negative
- We had a hard developing this lab successfully. In hindsight, I think we failed to appreciate the need to heat the reaction in Part II to a much higher temperature than would be achieved by simple reflux conditions.
– In my opinion, working with bromine and ethyl ether should be avoided whenever possible.

Inquiry & Extension ideas.
● Could be part of an exploration of an Electrophilic/Nucleophilic Aromatic Substitution study.

Week 10: Synthesis of Chemiluminescent Esters

1) Source(s) This lab was developed by a team of students from a recent JCE article: “Synthesis of Chemiluminescent Esters: A Combinatorial Synthesis Experiment for Organic Chemistry Students,” Duarte, Robert; Nielsen, Janne T.; Dragojlovic, Veljko. J. Chem. Educ. 2004, 81, 1010. A good resource for this experiment is a website: “Chemiluminescence of Oxalate Esters” http://www.chem.leeds.ac.uk/delights/texts/VV_exp_26.htm

2) Changes to published procedure
We scaled up the procedure and worked without a drying tube on the reaction flask.
We evaporated the acetone with forced air rather than a rotary evaporator.
We limited the choice of phenol to: 2,3,6-trifluorophenol, 2,4,6-trichlorophenol, 4-nitrophenol, and 2,4-nitrophenol.
The fluorescent indicators we used were rubrene, and 9,10-diphenylanthracene.
We performed a UV scan of the products.

3) Positive
+ Chemiluminscence is a cool phenomenon. A nice break from the syntheses of white powders and clear liquids.

4) Neutral
± This was the most expensive lab to prepare for us.
± The chemiluminescence does not last long: mix the peroxide into the mixture while in a darkened room.

5) Negative
- Most of the combinations (phenol and indicator) proposed in the article don’t chemiluminesce. It seems like a good idea for each student to synthesize at least one product that gives off light.

6) Inquiry & Extension ideas.
● “Let’s make glowsticks,” one student said.

Week 10: Synthesis of Isopentyl Acetate (Banana Oil)

1) Source(s) This lab was developed by a team of students from a website: “Preparation of Banana Oil” http://cas.bellarmine.edu/chem116a/lab/banana_oil.htm. Many websites and lab manuals have versions of this very same experiment. I performed this experiment in 1979 from Pavia D. L.; Lampman G. M.; Kriz G. S. “Introduction to Organic Laboratory Techniques: a contemporary approach” 1^st edition 1976 W. B. Saunders Company.

2) Changes to published procedure
We used 9 mL of isopentyl alcohol (3-methyl-1-butanol), 12 ml acetic acid, and 3 mL H₂SO₄.
Reflux was done for 40 min.
The routine liquid-liquid washings were done.
The ester was distilled to its final purified form.
We performed an IR spectrum of the products.

3) Positive
+ A classic experiment that covers an important reaction.
+ The product is easy to put between salt plates for the IR.
+ It smells nice. Well, about as nice as any organic chemistry experiment is going to smell.

4) Neutral
± It seems like a lot of acid is needed. Isn’t excess acetic acid enough acid?
± During reflux the mixture turns a dark color. Is this because of impurities in the alcohol?

5) Negative
- This would be much more interesting if the students could mix-and-match several alcohols and carboxylic acids. Wade P.A.; Rutkowsky S.A.; King D.B. A simple combinatorial experiment based on Fischer esterification - An experiment suitable for the first-semester organic chemistry lab. J Chemical Education 2006, 83(6), 927-928.

6) Inquiry & Extension ideas.
● The combinatorial approach is very cool. Any carboxylic acid matched with a primary alcohol should give a decent yield. At a certain point it would be impractical to distill the resulting esters, possibly.
● Acid-catalyzed reactions have the option of changing the acid.
● Acid-catalyzed reactions always have the possibility of interesting side reactions occurring: eliminations, polymerization, etc…

Week 9: Synthesis of Azo Dyes

The inspiration for this experiment is from: “A Combinatorial Experiment Suitable for Undergraduate Laboratories” by Benjamin W. Gung and Richard T. Taylor. Journal of Chemical Education, Vol 81, No. 11, November 2004.

2) Changes to published procedure
We doubled the quantities used in the JCE article.
The 2.6% aqueous sodium carbonate solution was prepared ahead of time.
The first part was done in beakers and no test tubes.
In 2008, we used the 3 positional isomers of aminobenzenesulfonic acid with 1-naphthol, 2-napthol, and 1-bromo-2-napthol. The latter nucleophile was a new addition to the scheme. 

3) Positive
+This experiment goes well with the “reactions of benzene derivatives” chapter.
+ Its colorful. The multifabric strip is a unique analysis technique - a little variation from the characterization of a white solid by melting point.
+ I really like these combinatorial schemes where students can comtrast and compare their products.

4) Neutral
±A precipitation is not really necessary in Part I. 
±In Part II, a little additional concentrated HCl helps with the final precipitation.
±If the student does not get a precipitate, they use the colored solution as a dye bath in Part III.
±The 1-bromo-2-naphthol behaved well. Unfortunately it had a pretty strong bromine odor. 

5) Negative  
-It may be rather difficult to determine the actual structure of the products. Has this ever been done? Is it a mixture, or what?6) Inquiry & Extension ideas.
=Combinatorial schemes are always interesting to contrast and compare products.
=Could be incorporated with alot more information and discussion on the interactions between dyes and fabrics. Why do certain fabrics “hold” certain dyes?
=It is possible to vary the nucleophile (e.g. naphthol derivative). It may be possible to vary the sulfonilic acid too. Alot of possibilities!
=At one time in the past I used a study of chemical dyes as a semester-long project. There is so much chemistry history associated with the dying industry. There is also a whole field of natural dyes that can be explored.
=I ofen pair this up with a “Natural Dyes” lab where we dye the same multifiber strips that we use in the “Azo Dyes” lab.
=I am interested in learning how to use a document scanner to measure (quantitate) the optical properties of the different fibers on the dyed strips.