Sunday, September 28, 2008

ATR Arrives in FTIR Lab

Long before I began teaching the undergrad orgo labs full-time, I was a TA for this course when I was a chemistry graduate student at UIC. At the time, there were few analytical techniques available for the characterization of organic molecules: no melting point apparatuses, no IR, no TLC and a sporadically functional GC with an unbearably slow analog plotter. A typical synthesis lab was often concluded by the students proudly shoving a yellow powder at me exclaiming, “See, I did it.” Sadly, I would acknowledge their accomplishment with a solemn nod, after which they would chuck their powder into the waste container with a strange jubilation. What was the point, I wondered. That yellow powder could have been anything. After about three years as a teaching assistant for this course, I was shocked one day when I found an infrared spectrometer in what is now the instrument room. I couldn’t believe we weren’t using this equipment in our labs. When I was hired as the full-time instructor, I made utilizing the IR my first priority.  Of course, I quickly realized why this technique had been left by the wayside for such a large class: time. Time training TA’s and students, time creating instructional handouts, and time maintaining the spectrometer were all factors, but the time that it took students to acquire a decent spectrum was the most formidable challenge of all—primarily because of the difficulty students had with sample preparation. For liquid samples, students sandwiched a thin film between two NaCl plates. After the tenth plate was ruined by accidentally washing with and thereby dissolving in water, we switched to disposable PTFE cards. These worked well enough, but it was difficult to get spectra of volatile samples.

Solid samples had to be ground with anhydrous KBr and pressed with a die into a transparent disc. While seemingly straightforward, a number of conditions had to be met precisely right in order to obtain a disc of sufficient transparency and with a high enough sample concentration to acquire a spectrum in less than 5 minutes. The tension was palpable during these labs, especially when time was running short and the line for the IR wound outside the instrument room like a snake threatening to choke the sanity out of student and TA alike.

I’m happy to say, those days are over. The attenuated total reflectance (ATR) accessory, which I have fought to acquire since I began teaching this course, has arrived thanks to the differential tuition money that was made available to the Chemistry Department this year. After several tedious hours of tuning, aligning and swearing, the Pike Technologies GLADiATR was successfully installed. Then came the time of reckoning. After acquiring 64 background scans, I nervously applied a small amount of solid acetanilide to the 2 mm2 diamond crystal, lowered the pressure clamp and then turned the clamp dial clockwise until the pressure tip had pressed the solid into the diamond at 40 pounds of force. I clicked the scan icon on the screen and one minute later I was looking at my first successful ATR spectrum. The results were amazing. The total acquisition time from start to print was 3 minutes—a far cry from the 20 minute average for the KBr technique. Could it really be this easy? After twenty or so spectra later, the answer was a resounding yes. I was ecstatic. It’s a great feeling to know that this technology will radically change how IR is approached in CHEM 233 and I am anxiously awaiting to see how it will be received by the CHEM 233 students this semester.
Please click here for a full-color version of the instructions for using the GLADiATR accessory.

Tuesday, September 16, 2008

To iClick or not to iClick

A couple years ago I sat in on a lecture at UIC where the instructor was using technology that allowed her to poll her students during class.  She would ask a multiple-choice question, which was duplicated on the overhead projector, and then her students would punch in A, B, C, D or E on their hand held clickers before the timer expired. Within seconds, the results of the poll flashed on the screen—eerily reminiscent of a Who Wants to be a Millionaire lifeline. I was hooked instantly. Not only do I love gadgets, Millionaire and statistics of every kind, but it also seemed like an ideal method for communicating with students in large lectures. Any teacher worth their salt continually asks themselves, “are they getting it?” Some are even brave enough to ask out loud even though they know the question will likely be regarded as rhetorical and disappear into the echoes of the lecture hall. What better way to find out then a reliable polling system such as iClicker?
You are wondering, of course, how this topic is relevant to the laboratory courses blog. In truth, it isn’t; however, next Spring I will be teaching one lecture of CHEM 232 (Organic I) and I am considering using this system. I’ve considered many of the advantages and disadvantages from my perspective. What I don’t know, however, is what students at UIC think are the primary strengths and weaknesses of this system. I would welcome any comments you have. Some key questions that must be considered are:

• What are good and bad polling questions?
• Should the system be mandatory?
• Should the questions be worth points? If yes, what percentage of the course?
• How many questions are too many in one lecture, one semester?
• Is the technology reliable? Is record keeping feasible?
• Will students remember to bring their clickers?
• How much do the clickers cost? Is this a financial burden?

Wednesday, May 7, 2008

Final Grades

Phew! Grades for CHEM 233 are done. You can find summary statistics on the Spring 2008 grades page. Because of the large number of students in the course, I cannot respond to emails for grade requests. However, I will hold office hours this Thursday and Friday (5/8 & 5/9) from 11am to 4pm specifically to meet with students to discuss grades. No appointment is necessary. You may also contact your teaching assistant. Based on the summary statistics, this was a very successful semester with an above average number of A's and B's. For most of you, your hard work has paid off. Congratulations on a job well done. Have a great summer.

Saturday, April 19, 2008

CHEM 233 Final Exam and Exam 2

The Spring 2008 CHEM 233 final exam is scheduled for Monday, May 5 from 6:00pm to 8:00pm. Please see the final exam information handout for information on the schedule, exam conflicts, policies, format and sample questions. There is a link to this file on the homepage as well as the shared files page. I will distribute a hard copy of the handout next week before your practical exam. Also, I just posted three sample exams for exam two.

Friday, April 4, 2008

The End is Near--And Yet So Far. . .

Wow, another whirlwind semester is almost done; it always seems to go by so fast. However, as I look at the upcoming schedule and the amount of work we have left, it seems like a long way yet to go. Perseverance, hard work and lots of coffee will get us their though. Remember that the week after your last lab is the practical lab exam (synthesis of luminol). I will provide you with an introduction and more details the week of your last lab (4/14-4/18) at the beginning of your sections; don't be late. Your laboratory notebooks are also due ON the day of the practical. Exam 2 is the following week (4/28-5/2); you will also check-out your lab drawers on that day. I will again post sample exams online within the next two weeks. Finally, I will distribute a flyer with information pertaining to the final exam two weeks prior. The flyer will include policies, conflict procedures, sample questions, etc. Have a great weekend...

Monday, March 17, 2008

Call for Bulletin Board Pictures

FYI: I posted the exam 1 key for CHEM 233 on the bulletin board outside of my office as well as the curve & distribution graphs. As I posted the key, I noticed the bulletin board also needs to be spiced up with some new pictures. Pictures of you and your friends--in lab!! I have been meaning to take some new pics, but just can't seem to get around to it. So I decided that I'll leave you in charge of the pics. I'll give one extra credit point (max 5 points) to every CHEM 233 student who submits a picture which is approved to go up on the board. I will generally look for original, candid and lab oriented pics to post. Write your name and TA on the back and hand it to me or slide it under my door. If you see your pic on the board, you got the credit. Be safety conscious and be sure to ask permission before snapping a pic of your colleagues. Deadline: April 18.

Monday, March 10, 2008

CHEM 233 Aces Exam 1

Congratulations on a job well done. I was very pleased with the results of exam one; it was apparent the majority of you worked hard on this material. The sample exams also seemed to contribute to more focused studying. I was particularly impressed with the number of students who seemed to have mastered functional group recognition in IR spectroscopy. The approximate curve (grade cutoff's) and score distribution have been posted on the Spring 2008 Grades page under the CHEM 233 tab. Remember that this curve is only approximate; the full value of each of your scores will contribute to the final score, which is then curved. If you would like to discuss your score or believe there is a grading error, stop by during office hours and I'll be happy to look over it with you. Note: your TA's will not be able to make corrections to your exam since the score has already been entered into my gradebook. Again, great job.

Monday, February 25, 2008

CHEM 233 Sample Exams

I recently posted sample exams for CHEM 233. While I think studying from samples can be dangerous since this sometimes encourages students to memorize material rather than learn it, the samples communicate clearly the type, formate and difficulty level of content to be tested. My aim was also to eliminate any disparity between students without samples and those who acquired old exams from classmates who had previously taken 233. My recommendation is to use the sample exams as an evaluation tool after you have studied the material. Review homework questions, assigned reading, course manual readings and prelab lecture notes first, then attempt one of the samples to gauge how well you understand the laboratory concepts and techniques.

Friday, February 15, 2008

Lidocaine NMR Samples

The latest spectra are now posted online.  The lidocaine specs look pretty good!!  The final product, lidocaine bisulfate, is not very soluble in CDCl3, which is why some of you may have observed cloudy NMR sample solutions.  The book uses dimethyl sulfoxide (DMSO) for the NMR sample, which is much more polar and better able to dissolve your final product.  We don't have any DMSO currently, so CDCl3 will have to do; Navid's spectra turned out great in CDCl3 anyway.  Just be aware that the chemical shift values (ppm) for each proton signal will be slightly different than those reported in your textbook since chemical shift is solvent dependent.

Project Two: LFER of Benzanilides

The slides for Friday's (Feb. 15) lecture are now posted. Also, I updated the slides with each student's synthetic target assignments for Project Two. Plan your syntheses so that you will obtain approximately 200 mg of product. Because deciding on a recrystallization solvent system can be time consuming, I will tell you what system works best for the final product: water/ethanol.

Wednesday, February 6, 2008

Blog RSS Feed

For those students interested in subscribing to this blog as an RSS feed, click on the link entitled "Blog RSS Feed" at the bottom of the sidebar to the left of this page. There is another link above entitled, "RSS." This will simply open the RSS feed for comments only. To be honest, I'm not sure why that's there or how to remove it.

Homework with Hooke's Law

As many of you have already realized, there is a mistake in the textbook excercise # 5. You should use equation 8.4 (Hooke's Law), not equation 8.5. This question is very similar to 3 & 4. Also, while I'm on the topic of Hooke's law, let me point out that the masses in the equation refer to the mass of a single atom. The most common error is to use molecular weights, rather than atomic masses. You can find atomic mass by dividing the molar mass by Avogadro's number.

Thursday, January 31, 2008

NMR spectra online

NMR spectra for CHEM 333 will be acquired by Maria or Brooke each week. These spectra are later processed with iNMR and saved as a pdf file, which will be posted on this website. Each student is responsible for downloading and printing their own spectra each week. If you would like your spectra reprocessed, expanded, etc., send me an email and I'll get right on it. Free versions of iNMR are available (MAC only). If you'd like to upload your own data from the server and process it yourself with iNMR, stop by my office and I'll show you how.

All of your 1H-NMR spectra for benzocaine looked excellent. Great job on your Fischer esterification. We'll discuss the interpretation of 1H-NMR in class on Friday. See you then.

Tuesday, January 29, 2008


Andy Freeman has asked that I let all students know that Friday, February 1 will be the last day that the stockroom will lone out goggles. Reminder: Students without goggles will not be allowed to participate in any laboratory activity.

Lab One Transparency Corrections

Wow! It's hard to believe we're almost through week 3 already. CHEM 233 students: Be aware that there were a couple mistakes on the prelab lecture transparencies for Lab One. These errors have been corrected in the pdf version, which you can download here.

As most of you have found out, lab one is technically challenging. Your successful completion of the lab
on time depends to a large degree on your advance preparation. I strongly encourage you to carefully read the textbook material assigned in the lab manual--especially those sections dealing with new techniques such as boiling point, melting point and IR--before coming to lab. Your familiarity with these topics can potentially reduce your in-lab time significantly.