27 Jun Riley Embrey – University of Houston Week Four

Welcome back guys! This week was pretty busy with processing our data and organizing it into data sets, graphs, and models. Along with more NMR analysis, me and my amazing lab mate, Brylea, did some of our new reactions, including the synthesis of a cyclotribenzoin through benzoin condensation, and esterification, which is adding ester groups to the macrocycle. Below are some of the highlights of my week, and thank you for reading my post!

Monday: June 22nd

Benzoin Condensation with balloon pumping in N2 gas

Today we went over the process of synthesizing the cyclotribenzoin macrocycle. We reviewed the procedure and tweaked the amounts of starting materials to make a smaller batch. Me and Brylea were allowed to start the process of creating these molecules independently, first starting by cleaning all of our glassware. We then added our starting material, Isophthaldehyde, to a closed reaction where we then added equal amounts of ethanol and deionized water. We then learned how to replace all of the air in a closed system by using a balloon filled with nitrogen to enter through one end and push all the other air out the other side. After adding heat, we waited until the starting material fully dissolved before we added the catalyst, cyanide. At this point, we must wait around 48 hours for this reaction to complete and see how much product we have. Up until this point, I have been reading and watching these reactions, so I felt super fortunate to be able to do this whole reaction by myself. I still needed some guidance, so next time I hope to perform this reaction more efficiently and without needing as much assistance. 

Filtering the cyclotribenzoin product

Tuesday: June 23rd

There was an early meeting at 8 am with professor Baldelli discussing our final project, our poster. In about 10 days I expect to have my poster finished and polished, so these last few days are going to be a little hectic, as I still have to collect and process more data and learn as much as I can before I reach the last and final day. I absolutely cannot believe that we are already in the home stretch! It still feels like I am just getting situated, so it’s strange to think that I should be used to this by now. At 8:45, me and Brylea made it to our lab where we did another round of NMR titrations. Today we used Bromine and Iodide anions instead of our usual azide and chlorine anions, so as I analyze the data, I expect to see the protons behaving differently. After lunch, we got the results of our titrations. There are a few unknown spikes in this data, as well as the calculation of the binding constant contains a percent error over ten percent, which shows that our titrations may have unknown impurities. This means that we will have to redo these titrations and hopefully get a result consistent enough to publish. I checked my benzoin condensation reaction, noting that the color has developed into a light brown-orange color. This means that the reaction is progressing as expected, as the desired product is a yellowish-white precipitate. I am excited to see if we get a desired yield and product tomorrow morning! 

3D Model of macrocycle from SCXRD (single crystal x-ray diffraction)

Wednesday: June 24th

Our reaction was finally complete when we came into the lab. We then started the next steps of the benzoin condensation reaction by transferring our mixture from the roundbottom flask into a vacuum filtration system. Using deionized water, ethanol, then diethyl ether, we washed the product to separate it from all impurities. After rinsing, I crushed the product into small bits so it would dry faster. After drying, I put the product into a vial, and ran an NMR spectrum of the cyclotribenzoin.  As we waited for the NMR to complete, we weighed the remaining amount of product we had left. Then, we calculated the percent yield of our reaction. I’m not sure what I may have done, but my yield ended up coming out as 35%, which means some of my product might have been filtered out as it is slightly soluble in ethanol. We then went and toured the X-ray room where single crystal X-ray diffraction is performed. Me and Brylea watched how for this process, you must separate one single crystal, a tiny fragment seen through a microscope, and put it on the tip of the mounting pin. As light enters the crystal, the waves crash into the electrons. As this occurs, these light waves can amplify, and as these amplified light waves exit the crystal, they go into the X-ray detector. The machine can then determine where the electrons are most dense, and thus map out where the atoms in a molecule must be. As this machine spins, it generates a 3D model of the molecule that makes up this single crystal. Although this is a smaller portion of my project, this was probably one of my favorite sections we did. Under the microscope, the crystals are always so beautiful, and separating these teeny-tiny crystals makes you feel like a surgeon. In the next week or so, I get the opportunity to work more with single crystal X-ray diffraction! 

Thursday: June 25th

Me and Brylea left to our own devices!

Today was very busy and tedious as I collected all of my data from the last week into my presentation. Although I did not have any labwork today, I did have to go and make sure all of my labels were accurate, my graphs are comprehensible, and that everything looked polished before I showed my professor my progress. I assembled all of my binding constants and put them into an organized table, where you can view the constants of different macrocycles hosts binding with different anions guests. However, as we worked through the day, me and Brylea noticed something mysterious brewing in the office. We spent most of our day being haunted by a bug we refer to as Reginald. In Colorado, I have never seen quite a creepy and large  looking beetle, and that, in solitude, may be the only thing I will not miss once this internship is over. Reginald seems to follow us wherever we may go. He has been spotted on top of the shelves, looking over us. He has been found creeping on the backs of our computers. The only thing Reginald is known to do repeatedly, however, is creep on us only when we are not focused on our work. He has been terrifying, but the more I see him, I understand that I must lock in. Reginald may terrify us to the point where we cannot sleep at night, but in unison, Reginald is the sole reason I got my work done that day. In life, make sure you recognize your reginald, and remember to thank him. Anyways, at the end of the day, we watched Reginald crawl into someone’s bag and get carried away into the sunset. 

Friday: June 26th

Esterification Reaction: Cyclotribenzoin acetate on the left, cyclobenzoin trimethylacetate on the right

On Friday, we found out that Reginald, in fact, did not get carried away. Soon, we found that he may have known that we had hoped he was gone, and he came back for vengeance. As I was working on my presentation, I had only noticed that he had come back when he emerged from the depths of my backpack, as if he’d been there all along. I took advantage of the timing, and I grabbed the nearest notebook and clobbered him against my desk. While I will miss his presence, I will not miss the fear he caused me and Brylea to feel over these past few days. Rest in Peace, and in one flattened piece, Reginald. Now, with a newfound sense of clarity, I got right to work on my final project. For the Welch interns, they have to write a report as well as assembling a presentation, and finally designing a poster. For the Pinterns, however, we only have to make a poster, and prepare to present that poster by next Friday. With our extra time, I intend to make my poster as polished as I can. I am not sure who will be attending the presentations, so I am going to go over all of my notes to master as much knowledge as I can beforehand. We took a quick break by performing an esterification reaction. There were two different reactions derived from the initial cyclotribenzoin we synthesized. There was the synthesis of cyclotribenzoin acetate or of cyclotribenzoin trimethlacetate. I did the former reaction, while Brylea did the latter. Essentially, you take the cyclobenzoin and dissolve it with acetic anhydride to get the ester groups, or you can dissolve it with trimethylacetic anhydride to get the trimethyl groups. Once you add a few drops of H2SO4 (your catalyst), the reaction will take approximately 6 hours to complete. My reaction, the synthesis of the Cyclotribenzoin acetate, turned colors immediately upon the addition of the sulfuric acid, while Brylea’s reaction took longer to change colors, as her reactants are less soluble.  

Outside the lab: Weekdays

Barbecue with Faye, Cricket, and Haebin!

Whenever I wasn’t occupied in the lab, I made sure to do something fun every day. I often found myself getting boba tea and matcha lattes at local cafes and starbucks. I have explored all the nearby shops, from antique stores and thrift shops, to ice cream parlors and the campus store. More often than not, I found myself just walking around campus looking at the scenery. Here, the vegetation and climate allows many insects, amphibians, and mammals to occupy much of the campus space. With the overly friendly squirrels and freaky looking birds (what I think are night herons), there is never a quiet moment on campus. Even at night, you can hear the rattling of katydids and the chirping of crickets. On Wednesday, we tried a really good

Lunch date with Brylea <3

 barbecue place near the SERC center, and on Friday, we found out that if you wear a red shirt, the school’s color, you get half price for the dining hall. Naturally, that means that I, along with Brylea, Haebin, Faye, and Cricket, all went to the dining hall together to eat lunch. 

Saturday – June 27

Saturday was a beautiful and sunny day, so the girls of the welch program all decided to have a pool day. We spent pretty much the whole day playing beach volleyball, tanning, and maybe, just maybe, putting on sunscreen. Nobody is sure what happened, but the fire alarm at the rec center went off, and everyone in the building had to evacuate to the other side of the road. While it was a little jarring, I saw it as good fortune because that inspired all of us to go get boba tea together. I ended my day by playing some cards, talking about books, and, of course, working on my poster project. Overall, I’m so happy I got the opportunity to not only work so closely with very knowledgable people, but also get to know them, as well as make many friends along the way! Thank you for reading, and see you next week for my last and final post!