bthoole's blog

In this lab, 1-propyl propionate was synthesized through the esterification of 1-propanol and propionic acid to get a percent yield of 19.81%. The product was assessed for smell and analyzed using IR spectroscopy. The smell of esters is usually something fruity and is a stark contrast to its alcohol and carboxylic acid components, which typically have an unpleasant odor. The carboxylic acid and alcohol are the reactants in the mixture, with the sulfuric acid serving as a catalyst. The reactants create an ester and water in a process known as Fischer esterification. This is a seemingly simple reaction where the carbon and hydroxyl group bond is broken in the carboxylic acid and a new bond is formed between that carbon on the carboxylic acid and the carbon chain bonded to the hydroxyl group on the alcohol. Protonation of the carbonyl carbon of the carboxylic acid makes it a better electrophile which undergoes 1,2 addition by the alcohol and a proton from the alcohol is transferred to a hydroxyl group. 1,2 elimination leads to a protonated ester before it is later deprotonated.

During the S and G2 phases of the cell cycle, along with the growth and DNA synthesis, part of the cell’s preparation for M-phase includes the duplication of centrosomes. Centrosomes are the microtubule organizing centers in cells and create the spindle poles during M-phase. Microtubules are protein fibers made of tubulin and along with actin and intermediate filaments, make up the cytoskeleton. Not all microtubules are the same and the differences give polarity and directionality to the fibers. They are made of subunits of alpha and beta tubulin. The microtubules extend from the spindle poles of the centrosomes on either side of the cell during M-phase and overlap in the center where other proteins hold them the overlapping units together, thereby stabilizing the spindle system. This utilizes kinetochore microtubules and interpolar microtubules. Meanwhile, the third type of microtubules, aster microtubules, connect to the cell cortex with other proteins.

Overall, the percent yields were high and the melting points were close to the literature values, suggesting a good return on product and a relative purity in the samples. The first recrystallization experiment used a set amount of acetone, 1 ml for every 50mg of crude product from the isolation. As a result, the percent yield was the lowest of the experiment. If the experiment were to go about obtaining the purest samples, this stage of the experiment should have been conducted by using the minimum amount of acetone necessary to dissolve the product. This would have given a higher percent yield and may also have given a better purity and thereby a closer match for melting point. In the end, the identity and purity of the products were assessed for what they were, and the product after both recrystallization steps was identified as trimyristin and the product after the hydrolysis and acid addition was identified as myristic acid.

After the extraction, the product yield was 0.622 g which was a 59.35% yield from the mass of the nutmeg that used. The extraction is the first step to isolating the trimyristin from nutmeg and the product from the extraction was recrystallized to purify it. The percent yield after the first recrystallization was 25.08%. The melting point for this product was between 54 and 56 °C. The literature gives a melting point range of 56-57 °C for trimyristin. The range matches closely and the crude product upper limit is the same as the given lower limit for trimyristin. The first recrystallization product can therefore be confirmed to be trimyristin and the slightly lower level in melting point suggests it is not yet a pure sample. After the recrystallization, a melting point between 55-56 °C is achieved for the product. Some of the material was used for the hydrolysis, but what was used to recrystallize gave a 72.91% yield. The melting point range decreased by 1 °C and moved closer to the literature range for trimyristin. As the second recrystallization was of the crude trimyristin product of the first recrystallization, not changes should have occurred, and the product can be identified as trimyristin. The 0.062 g taken from the first recrystallized product was used in the hydrolysis and acid addition part of the experiment and gave a product that after drying weighed 0.049 g which gave a 79.03% yield in product. The dried sample also had the melting point taken and was recorded at 54 °C. The literature gives a melting point value of 54.4 °C for myristic acid, so the product of hydrolysis and acid addition can be identified as such.

In this lab, trimyristin was isolated from ground nutmeg and recrystallized to get a percent yield of 72.91%, as well as hydrolyzed to produce myristic acid in a 79.03% yield. The ground nutmeg seeds were refluxed with tert-butyl methyl ether to extract the crude trimyristin which was then recrystallized with acetone to purify the trimyristin product. The other soluble components of the nutmeg remain in the acetone solution while trimyristin recrystallizes out. Trimyristin is a triglyceride, which is a triester of the trialcohol glycerol and a long chain, unbranched carboxylic acid. Hydrolysis of a triglyceride yields one glycerol molecule and three carboxylic acid molecules for every molecule of fat. When trimyristin is converted into glycerol and myristic acid through saponification, the addition of the sodium hydroxide creates glycerol and sodium myristate and with the addition of acid to the sodium myristate causes a change to a carboxylic acid, thus forming myristic acid in this lab. The addition of acid causes the sodium salt to leave the sodium myristate and allows for the hydration of the now unbound oxygen which provides the mechanism for the alcohol group formation on the carboxylic acid.

The first poster I looked at was the “Mind-wandering in chronic pain and control participants during a smartphone-based mindfulness task” by M. A. Azam, MSc, V. Latman, MA, & J. Katz, PhD. I liked that it had color to break up the poster, but this was almost a necessity since it did not have a lot of figures or charts. It was mostly comprised of words, but each section was kept brief and had large text which made it easy to read. I liked that it was organized in columns and went from left to right, which made the flow easy to follow. The first figure they used was also made of mostly words and acted as a flow chart. Overall, the poster lacked an eye catching graphic or figure or something that would stand out amongst the columns of text that is provided.

The next poster I looked at was “Effects of socio-economic and cultural factors on the ALSFRS-R in South African ALS patients: A pilot study” by Anna Caroline M.A. Braga (MSc PT), Franclo Henning(MD). This poster had a different reading flow and instead of going left to right went from top to bottom. The middle of the poster that followed the methods and preceded the results was a nice break in the text and was mainly a series of graphics and flow charts that helped to explain the process and experiment. It was easy to look at and understand and didn’t have sentences. This was also the only section of the poster which had color which drew the eye to it immediately and held the attention. However, its only color was in a few directional arrows and overall the rest of the poster looked plain and no different than if a paper had just been expanded and printed out.

The third poster I looked at was “Implementation of wireless device to monitor cardiorespiratory response to aerobic exercise in ALS patients at home. A pilot study” by authors Anna Caroline M.A. Braga MSc PT, Anabela Cardoso Pinto MD PhD; Mamede de Carvalho, MD PhD. This poster was the most aesthetically pleasing, with a background color and multiple figures that were of different tables, charts and graphs. They put this in the middle of the poster which had the background, aim, methods, and two different boxes for exercise protocol and explaining a monitoring system. The bottom had the results/discussion grouped together and then the conclusions. The two written sections comprised about the same space and were thorough and brief.

The TLC analysis provides a means to separate the structures that are present in the sample that was spotted and measure the retention factor to compare amongst the other samples. By spotting the plates as they were, plate one can compare the starting material to the recrystallized product and plate two can compare the starting material to crude product. As seen in Figure 1, the starting material benzoin and the crude product produced one spot. When the two were overlapped, the result was two spots. The eluant traveled 4.8 cm while in the TLC chamber and provided a way to measure the retention factors for how far each spot traveled. Table 1 provides the retention factors and shows that the retention factor generated for benzoin on the first plate was 0.844 and the recrystallized product was 0.533. The mixture of spots located at spot C on the plate produced two marks with Rf factors of 0.844 and 0.644. The similarity seen here is representative of overlap of the spots and is expected to be seen. The spots that share the Rf factor of 0.844 can be identified as benzoin and the second spot can be matched to the recrystallized product. A similar trend was seen in the second plate in that the starting material and crude product produced one spot, where as the mixture produced two. The second plate, however, had Rf factors that were even closer in directly matching the Rf factor of the singular spots. The starting material had an Rf spot of 0.813, which is similar to plate one with the expected difference occurring from the distance travelled by the eluant, and the mixture had an Rf of 0.833. Meanwhile, the crude product had an Rf factor of 0.604 and the mixture had a second Rf value of 0.625. The mixture has Rf values that are slightly higher than the singular spots, but when looking at Figure 1, it appears that the spots from location C have shifted on the paper, which can be explained as that side being exposed to the eluant first. If slight drifting did occur from exposure upon placement in the TLC chamber, then the one side would have been exposed for longer time and have longer time to travel up the paper. Overall, the shifting was not major and the values are close to each other that they are comparable to determine they are the same. The recrystallized product that made spot B on plate one is 0.533 and is lower when compared to the crude product on plate two. The mixture of recrystallized product produces an Rf value of 0.644 that is much more consistent with the crude product results on plate two, 0.604 and 0.625.

In this lab, benzoin was reduced by the addition of sodium borohydride. The product was identified as 1,2-diphenylethane-1,2-diol based on analysis of the reaction mechanism and comparative melting points taken from the literature. Sodium borohydride is a metal hydride that is capable of serving as a reducing agent. The reducing agent contains a metal hydrogen bond that is the source of a hydride ion. Sodium borohydride is a more selective reducing agent because of the polarity between the boron and hydrogen bond and as a result will only reduce aldehydes and ketones. The addition of sodium borohydride along with hydrochloric acid to the benzoin in ethanol provided the necessary components of the reaction to occur. The double bond to the oxygen in the benzoin was attacked by the sodium borohydride so that it became a single bonded negative oxygen which was then capable of reacting with the hydrogen provided by the addition of hydrochloric acid and water. The quenching allowed the negative oxygen to bond with hydrogen and become a hydroxyl group. The reduction reaction causes oxygen to lose bonds and, in this case, the double bond to oxygen in benzoin became a single bond to a hydroxyl group in hydrobenzoin. A crude product was generated as a first step and then recrystallized to purify the product. The purified product, along with the starting material and crude product were then analyzed with thin layer chromatography and melting points.

This study will serve to identify a key aspect of the crab spider’s vision and whether or not the intensity of blue light affects the spider’s ability to match the color provided. It is known that the spider is able to change from yellow to white, but it is not known if it has a preference of those colors, or if it will change slightly if neither color is presented. The color yellow is seen by the eye as a reflection of white light with the absence of blue, meaning it did not  absorb the red and green light. We wondered if the spider’s ability to see yellow was based on the absence of blue light, and if so, how other colors that matched an absence of reflected light would affect the spider’s ability to change color. We do not expect a color change match, but are looking for variation in color change for different color environments.

 

Other experiments have been conducted that tested the color background preference in a species. The background color preference in tadpoles was tested to see if they preferred a white or black background (Moriya ,Kito ). They held the tadpoles in either a black or white container since hatching and then transferred them to the test container which was divided into white or black halves on the bottom and halfway up the walls using acrylic plates. This methodology is emulated in the design of our test boxes which will also split the tank in half and cover the floor and entire walls with the selected color  because of the spider’s ability to climb. We will be using printed poster paper to get the desired colors and cover the exterior sides of the clear tank so that the color is seen on the inside.