Years of industrialization and little to no regulation on what can be emitted into the atmosphere has led to a changing climate which will only grow worse with time. The current shared opinion among scientists is that humans need to limit the rise in temperature to only two degrees Celsius above preindustrial levels in order to avoid a point where the increase in temperature reaches a point where it would no longer be able to be controlled or averted. Currently, climate change is occurring because of the presence of “greenhouse” gases in the atmosphere, mostly methane and carbon dioxide. These gases act as a blanket of sorts for the earth and trap incoming radiation from the sun, thus heating the planet. This process drives other factors that then contribute to the increased temperatures as well. With the increase in temperature, glaciers and other land bound ice are melting and raising sea levels. This affects global temperature in two ways. The first is that the ice normally serves as a source of albedo that stops the sunlight from being absorbed by the darker colored earth and reflects it back into the atmosphere. The second is that as sea levels rise, it provides more water to absorb heat, again raising temperatures. These are just two examples of how climate change has the potential to reach a tipping point that, if reached, will not be able to be stopped.
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A one to one mixture of alcohol and carboxylic acid will usually yield an equilibrium mixture that is about 70% ester. The experiment carried out did not use a one to one ratio and instead used 13 mmol of carboxylic acid to 11 mmol of alcohol. This was in an attempt to react all the alcohol and not limit it, but the reaction of 1-propanol and propionic acid produced a percent yield of 19.81%. The final product of ester after the drying work up was 0.253 g when the theoretical put the grams of 1-propyl propionate ester at 1.255 g. The final percent yield may be the result of an incomplete separation during the reflux between the water and organic layers. The reflux filled the side arm quickly and required the top layer to be dumped back into the round-bottom flask multiple times during the 15 min heating period. A higher ester yield may have been possible if the separation occurred at a slower rate so that the side arm did not fill so quickly, or if the side arm were larger. If the side arm were larger, it would allow for more catchment and a more defined layer to distinguish the organic from the water. The better distinction would also allow for only the organic layer to be removed after the 15 min reflux. Given that the reflux did not completely separate the organic product from the water, some of the ester may have been removed as the aqueous layer during the work up which would have lowered the final volume and therefore the percent yield. Still, the IR analysis confirmed the existence of an ester based on the peaks seen, so the esterification reaction between 1-propanol and propionic acid was successful in producing 1-propyl propionate.
The final product was also qualitatively assessed for odor and compared to the odor of the other esters and the starting products used in the reaction. The esters shared a sweet-smelling, fruity odor. The 1-propyl-propionate ester formed in the final product had a smell of pineapple or pear, which was distinguishable from the other esters which had a more banana like fragrance. The product also had a slight odor of alcohol, similar to that of nail polish remover, which ma be detectable traces of alcohol which was seen present in the IR spectrum. The starting components, 1-propanol and propionic acid did not share the fruity fragrance of the final ester and were instead unpleasurable scents. Both had a rancid odor, with the 1-propanol being similar to that of ethanol, another alcohol.
After the solution was refluxed to worked up to remove the water, the final product was analyzed using infrared spectroscopy. The spectroscopy analysis provided peaks that correspond to that of an ester, which is what was expected and can confirm the esterification process in the synthesis of 1-propyl propionate. The IR spectrum showed a peak just to the right of 3000 cm-1 at 2972.43 cm-1. This peak corresponds to the alkyl carbon-hydrogen bond in the ester. The stretch that starts at peak 1740.83 cm-1 is a measurement of the double bond between carbon and oxygen. These are the results that would be seen in a sample of pure ester, but the IR spectrum also gives peak values above 3000 cm-1, which suggests impurities containing a hydroxyl oxygen and hydrogen bond. The peak is highest at 3453.69 cm-1. This impurity could be a result of left-over water or a result of alcohol contamination from the 1-propanol.
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.