Purchase of a Polarimeter for Organic Laboratory Courses

Project Title: Purchase of a Polarimeter for Organic Laboratory Courses

Project Lead’s Name: Ben Gung

Email: gungbw@miamioh.edu

Phone: (513) 255-2428

Please Choose the Primary Affiliation: CAS

Are There Other Project Team Members?: Yes

Other Project Team Member: Dominik Konkolewicz

Other Team Member Email Address: d.konkolewicz@miamioh.edu

Other Project Team Member: Scott Hartley

Other Team Member Email Address: scott.hartley@miamioh.edu

Brief description of project: This project involves the acquisition of a polarimeter for organic laboratory courses in the CHM 244/245, CHM 254/255, and CHM 419 courses. The CHM 244/245 and CHM 254/255 are the laboratory courses associated with the year long Organic Chemistry lecture courses CHM 241/242 and CHM 251/252. The CHM 419 is the Advanced Synthesis Laboratory for chemistry majors. 

Stereochemistry is a fundamental concept in organic and biochemistry. Chirality is a branch of stereochemistry involves enantiomers or mirror image isomers. Most biologically important, naturally occurring substances are chiral. Therefore it is important to expose biology majors to chiral chemistry. 

Experiments that are of more fundamental interest to students in the biological sciences were introduced into the CHM 244/245 series during 2011-2014. The redesign of the course led to a student tech fee proposal in 2014 to introduce inexpensive entry level polarimeters into the CHM 244/245 laboratories. Those simplified devices were utilized in experiments in CHM 244/245, but they failed to provide our students with the stereochemical identification originally expected. The main problem was the inaccuracy of the results and the time it takes to measure and derive optical rotations. 

Historically there was one experiment in CHM 419 that produced optically active product. A research grade polarimeter in the research laboratory of Dr. Gung was used to measure the optical activity of the product. Since CHM 419 is mainly for senior chemistry majors, the enrollment is relatively small (~15) and the use of a research instrument once a year posed no serious problem. The polarimeter in the Gung group broke down after 25 years of usage. In addition, the experiments recently introduced in CHM 419 have gradually updated to include more modern organic asymmetric syntheses. Therefore three more experiments now need to use a polarimeter. 

Both CHM 244/245 and CHM 419 need to have access to a polarimeter for measuring optical activity of chiral compounds and complexes. In this proposal we ask for student tech fee funds to allow us to purchase a research-grade polarimeter for the organic laboratory courses to enhance recently introduced new experiments and to provide fast, accurate measurements.

Does this project focus on graduate student education or graduate student life?: No

Describe the problem you are attempting to solve and your approach for solving that problem.: Stereochemistry, also known as 3D chemistry, involves the study of the relative spatial arrangement of atoms that form the structure of molecules. An important branch of stereochemistry is the study of chiral molecules. A chiral molecule is non-superimposable on its mirror image. The mirror images of a chiral molecule are called enantiomers or optical isomers. Individual enantiomers are often designated as either "right-" or "left-handed". Chirality is an important consideration when discussing the stereochemistry in organic chemistry. A polarimeter is a scientific instrument used to measure the angle of rotation caused by passing polarized light through an optically active substance. The amount by which the light is rotated is known as the angle of rotation. Optical rotation is essential for identifying enantiomers since otherwise enantiomers have identical physical properties. 

An experiment that was introduced into CHM 244 in 2012 had students explore the stereochemical outcome of a substitution reaction on a naturally occurring amino acid, L-phenylalanine, and its enantiomer, D-phenylalanine. The amino acid substrate was chosen to maximize the interest of biological science majors, and the experiment was chosen to demonstrate stereochemical principles that are being taught simultaneously in the Organic Chemistry lecture course, CHM 241. The experiment was run successfully, but stereochemical analysis in the experiment relied on the previously purchased inexpensive entry level polarimeters to detect the stereochemistry of products. Unfortunately the simplified polarimeters gave erroneous results, sometimes showed optical rotations even when racemic samples were measured. In addition these instruments took unreasonable amount of time in the measurement and derivation of the optical rotation. With the large enrollment of the CHM 244 course, this turned out to be impractical. 

Modern stereochemical analysis relies on polarimetry and the knowledge that two enantiomeric compounds rotate the plane of plane-polarized light in opposite directions. The research grade polarimeter is more sensitive than the simple inexpensive polarimeter because it is equipped with a light source and a processor. The time to take one measurement is literally just a few seconds. Each student prepares his/her sample solution and places the sample cell inside the measuring chamber and close the lid. The digital readout immediately shows the optical rotation degree with either a + or a - sign. The technique is described in all undergraduate organic chemistry texts, but has not been used extensively in undergraduate organic laboratory courses because of the expense of the equipment. Other larger schools, such as Ohio State University and University of Cincinnati, do have research-grade polarimeter for their teaching labs. The Tech Fee funds will make it possible for Miami students in large enrollment organic laboratory courses to gain experience with the research-grade polarimeter. We propose to purchase one research-grade polarimeter to make the student experience in the laboratory course more similar to that in a modern research laboratory in which stereochemical analysis is employed.

In addition to the experiment described above, another experiment introduced in the spring semester of 2013 in CHM 245 will be enhanced by the introduction of the new polarimeter. In that experiment students perform a one-step synthesis of a racemic mixture of guaifenesin enantiomers, a component of many over the counter cold remedies. A chiral synthesis of the pure enantiomers starting with relatively inexpensive chiral starting materials was introduced when polarimeters become available to perform routine stereochemical analyses. Part of the rationale for this experiment is to point out that certain drugs must be generated as pure enantiomers to maximize effectiveness and drug safety, so student involvement in a simple chiral synthesis would drive that point home. 

In the majors' CHM 255 laboratory course a three week project involving the diastereoselective synthesis and purification of a chiral secondary amine starting from a chiral primary amine is planned. Chiral secondary amines are finding use as catalysts in enantioselective syntheses, so this project serves as an entry into discussions of the use of chiral catalysts in enantioselective synthetic procedures. The polarimeter will be utilized to monitor the success of the synthesis and the stereochemical purity of the product after recrystallization. This synthesis project is appropriate for a majors' laboratory course, but would be beyond the scope of a non-majors' laboratory course because it involves reactions performed under controlled atmosphere conditions and the use of sensitive reagents.

In the Advanced Synthesis CHM 419 laboratory course three chiral syntheses are being introduced this semester. These involve (1) Asymmetric Robinson annulation, (2) Chiral ammonium reagent preparation, and (3) Chiral resolution of binaphthol. All of the three syntheses need a polarimeter to identify the success of the laboratory and the reaction product purity. It will be very difficult, if not impossible, to demonstrate the principle of the chiral syntheses without the availability of a research grade polarimeter.

The criteria state that technology fee projects should benefit students in innovative and/or significant ways. How would you describe the innovation and/or significance of your project?: The Organic Chemistry lab courses CHM 244/245 and CHM 254/255 have served an average of 350 students in the fall term and an average of 280 students in the spring term over the last three years. Total enrollment in the combined courses has been approximately constant over the last five years, but enrollment has gradually shifted to the major's lab classes CHM 254/255. The Department has been advising students that the CHM 254/255 course is the preferred course for both BS and AB majors, so AB majors have been enrolling in that course in greater numbers. CHM 254/255 has been the required laboratory course for all majors starting with AY13/14. The enrollment in CHM 254 has been 70-75 students, with the enrollment in CHM 244 about 260-265 students.

The enrollment in both the CHM 244/245 and CHM 254/255 courses will remain significant for the foreseeable future, but the characteristics of the students in these courses has changed. In particular, CHM 244/245 is now populated almost entirely by biological science majors. This is the major reason for the ongoing curriculum revision in that course that is designed to make the CHM 244/245 lab course more relevant to biological science majors. 

The audience in the major's course has increased from about 25 students prior to AY 10/11 to about 70-75 students in the last two years, with the inclusion of all AB majors. Therefore, the equipment will serve a significant number of students in both lab courses.

The Advanced Syntheses Laboratory CHM 419 has a complete revised curriculum. One experiment in modern asymmetric synthesis is introduced into this course in 2015. Last year two asymmetric synthesis experiments were performed. Currently we have planned three enantioselective syntheses in this semester. A research grade polarimeter is usually a required apparatus in asymmetric synthesis.

Understanding stereochemical concepts is a fundamental component of both accompanying lecture courses, CHM 241/242 and CHM 251/252, and the mastery of these concepts is required for success in the lecture courses. For that reason, it is important that these concepts are reinforced in the laboratory courses. The polarimetry equipment will enhance student understanding of stereochemistry, and will provide students with a modern laboratory experience.

How will you assess the project?: The polarimeter will be utilized in CHM 244/245 next year (AY 17/18). They will be utilized in experiments that have been initially tested during the past a few years. The planned implementation schedule follows. For the CHM 244 substitution experiment on L-phenylalanine and the guaifenesin synthesis, the polarimeters will replace the current entry level devices. 

Student grades for both of these experiments in the absence of the research grade polarimeter will be available from the current academic year. These grades will be compared to grades for the same experiments in future years to determine the effect of the new equipment on student learning and performance. 

Since the experiments are being developed in an effort to make the lab course more relevant to the students taking the course, students will be polled at the end of each semester to determine their views on each of the individual experiments. The results of the student polling will be utilized to help guide future changes in the course. 

The new experiment for CHM 255 will be carried out first by graduate TAs to assess the viability and timing of the procedures. Starting in the spring of 2018, this three-week project will be implemented in the final weeks of the CHM 255 laboratory course when students have familiarized themselves with common organic lab skills. The new techniques introduced during this project include the use of polarimetry to determine stereochemical purity and the performance of the reactions under a controlled atmosphere of gases. During this project, all of our available TAs will help supervise the undergraduates. The first reaction of this series includes a 2 hour stirring time. TAs will instruct the undergraduates on how to use the polarimeter during this period. Evaluation of this new lab experiment will use a survey for students to fill out to determine the extent to which the project meets its overall goals. Based on feedback from the students, the implementation will be revised to prepare for subsequent years in CHM 255. 

Currently there is no polarimeter in the CHM 419 laboratory. Since the experiments are being performed in an effort to introduce asymmetric synthesis to the students taking the course, students will be polled at the end of each semester to determine their views on each of the individual experiments. The results of the student polling will be utilized to help guide future changes in the course. 

In the corresponding lecture courses, student performance on exam questions related to stereochemistry will be monitored before and after introduction of the equipment to determine the effect of the equipment on understanding of stereochemical issues.

Have you applied for and/or received Tech Fee awards in past years?: Yes

If funded, what results did you achieve?: Yes, a Tech Fee proposal submitted in 2011 for the purchase of the Web MO program was funded in 2012. The incorporation of the Web MO program into the CHM 254/255 and the summer CHM 244 curriculum was done by assignment of molecular orbital calculations after the experiment involving charge transfer complexes was performed in the laboratory. After molecular orbital calculations via Web MO using Gaussian program on the RedHawk cluster, students were able to relate the color change in the complex solution to the calculated HOMO-LUMO energy gaps in the complexes. As a result, student experiences in this experiment of the laboratory courses were greatly enhanced. 

In 2014, Michael Novak (retired in 2015) led a tech fee proposal for the inexpensive entry-level polarimeters. That proposal was also funded as noted above, but student experience was not enhanced as originally expected in the related experiments.

Did you submit a final report?: Yes

What happens to the project in year two and beyond? Will there be any ongoing costs such as software or hardware maintenance, supplies, staffing, etc.? How will these be funded?: The polarimeter, including the prefocused halogen lamp, light sources is fully warranted for two years after purchase. The light source is expected to last the lifetime of the instrument. Each unit comes with one glass polarimetry cell. An additional two sample cells ($886/cell) will be purchased for the unit. This should provide for breakage of cells for a period of at least five years. The cost of these cells is included in the project budget. Future cell replacement costs can be handled by the Department. The department will commit to continued upkeep of the equipment.

Budget: Hardware

Hardware Title(s) & Vendor(s): 1 Polarimeter, Rudolf Research (1 Dell desktop, 1 monitor)

Hardware Costs: $21,709.00

What is the total budget amount requested?: $21,709.00