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.

Goggles

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.

Final Exam Room Change

There was an error on the informational sheet distributed before the practical exam. The correct room for the final exam are as follows:

Monday - Thursday sections: Lecture Center A1 (6:00pm-7:00pm)

Friday sections: Lecture Center B1 (6:15pm-7:15pm)

Sorry for the confusion. You can find and updated final exam info sheet on the shared files page.

Sample Exam 2 Posted

I posted a sample exam for exam #2 on the shared files page (233sample_ex2.pdf). You may work through this example to help you study. I do not recommend relying soley on this example; also look at homework questions and TA notes for additional material.

Stereoselectivity in E1

There have been several questions about the stereoselectivity of an E1 elimination mechanism. Two arguments can be made. A kinetic argument compares the relative energies of the carbocation intermediates leading to each product. The carbocation intermediate on the left is more stable than the carbocation intermediate on the right due to reduced steric strain; therefore the trans alkene is favored. Because this reaction is reversible a thermodynamic argument can also be made and is actually more correct; although the outcome is the same in this instance. Thus, the trans alkene product is favored because it is more stable (lower in energy) than the cis alkene. Trans is more stable than cis for the same reason already mentioned, less steric strain. Caution: thermodynamic arguments (comparing relative stabilities of products) can only be made when reactions are reversible (equilibrium). This reaction is reversible and explains why distillation was necessary to remove the alkene products and shift the equilibrium toward products (LeChatleir principle).

Final Exam

CHEM 233 final exam will meet according to the schedule below. The exams will start on time so please arrive early so that you may find your seat. Again, a final exam information sheet will be distributed on the day of your practical. Happy Thanksgiving.

Monday-Thursday sections: Monday, Dec. 10, 6pm-7pm, Lecture Center B1.

Friday sections: Monday, Dec. 10, 6:15pm-7:15pm, Lecture Center A1.

Weeks 14-16 Schedule

Week 14 (November 26-30): Practical Exam

Week 15 (December 3-7): Exam 2 and Drawer Checkout.

Week 16 (December 10): Final Exam, 6pm, LC A1 & B1. Please see final exam info sheet to determine which room your exam is in.

233 Final Exam Time

The final exam for CHEM 233 will be held on Monday, December 10 from 6-8pm in Lecture Centers A1 and B1. Because there are two rooms, the class will be divided in half. You will receive an informational sheet on the day of your practical exam that will indicate which Lecture Center you should attend. This info sheet will also contain sample questions, review topics as well as exam policies.

An Organic Chem Blog????

Well, I've finally entered the world of blogging after having spent probably hundreds of hours reading the blogs of others. It feels good, although I'm a little skeptical since I tend to be a perfectionist and reread my writing over and over until I am satisfied. I'm somewhat comforted that this blog is dedicated to organic chemistry--a topic I could write endlessly about. Initially, I anticipate the blog to more or less function as an announcement board for CHEM 233 and CHEM 333, especially for the remaining Fall 2007 semester. However, I certainly hope it can grow into a platform for initiating interesting discussions in chemistry. It may even be entertaining, but that might be stretching. . .