If 3 UV active spots were in the crude material and co-spot TLC plate, and only one spot had the same Rf as the starting material and the other 2 are very different, predictions for the 2 non-starting material spots could be something in the middle of the mechanisms. There are four parts to the mechanism, the one in the middle are the ones that alter the mechanisms. So the second and third part of the mechanism would be the 2 non-starting material spots. This is because of the rate of the hydride attack on the carbon double bonded to the oxygen. It depends heavily on the R group present, and the more electron deficient it is, the faster the hydride can attack. But because they are different from the starting material spot, it would mean that it was caught between and could not fully reduced and go to completion. If it were to be the 1st and 4th instead of the two in the middle steps of this mechanism, it would go through but it will not be full.
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If 3 UV active spots were in the crude material and co-spot TLC plate, and only one spot had the same Rf as the starting material and the other 2 are very different, predictions for the 2 non-starting material spots could be something in the middle of the mechanisms. There are four parts to the mechanism, so the second and third part of the mechanism would be the 2 non-starting material spots. This is because of the rate of the hydride attack on the carbon double bonded to the oxygen. It depends heavily on the R group present, and the more electron deficient it is, the faster the hydride can attack. But because they are different from the starting material spot, it would mean that it was caught between and could not fully reduced and go to completion.
First, add benzoin (0.5g) and ethanol (4mL) to an Erlenmeyer flask (25mL) swirling at room temperature until it is all dissolved. Add sodium borohydride (0.1g) using a micro spatula in small amounts for 5 minutes (swirl for addition 20 minutes at room temperature). Cool the mixture using ice bath, add water (5mL) after and 6M HCl (0.3mL). Wait 15 minutes to add more water (2.5mL). Then collect the product using vacuum filtration (reserve 1-2mg for TLC analysis) after 15 minutes. Recrystallize from acetone, using 25 mL flask. Let it all dry and come back for evening hours. MP, yield %, and mass needs to be determined. Dissolve a small amount of benzoin, using recrystallized product and reserved crude product in ethyl acetate. Spot 2 TLC plates, with starting material, reserved crude product, recrystallized product, and a spot that contains both in the middle. Run the TLC plates in 9:1 CH2Cl2: ethanol. Add eluent to TLC developing chamber, use tweezers to carefully put the TLC plate in the chamber and screw the cap. Allow the solvent to run from the baseline to about 1cm from the top. Remove the TLC plate when it is ready marking the solvent from it and allow it to dry. Use UV light and mark them once it is all dry. Tape the plates on a sheet of the lab notebook paper or take a picture and draw into the lab notebook.
The three known substances naphthalene, urea, and sulfanilamide were all provided with its relative MP ranges. Naphthalene was 79 degrees and I found it to be 80 degrees. Urea was given 132-134 but mine did not completely melt until it hit 137. Lastly, sulfanilamide was 165-167 but mine was 1 degree higher to be 168. For the two unknowns, I wasn't given the MP range so I had to start from 0 degrees and slowly raise the temperature. Unkown 8 that I was given which I did for my first unknown came out to have melting point of 95 which is why I thought it was acenaphthene with melting point of 94-96. Unkown #7 which I used for my second unknown came out to have MP 166 which is why I concluded that it was sulfanilamide once again because it had 165-167 degrees.
Did you ever notice that certain phrases used on a daily basis could carry so many different meanings depending on the situation and the intonation of the phrase? In South Korea, the phrase “yuh boh sae yo” is used on a daily basis. Yuh boh literally translates to husband or wife in English so only married couples use this term in Korea. So if you were married, you’d call your wife or husband yuh boh instead of their name. This is where it gets interesting because the phrase yuh boh sae yo can be said to anyone and not just to your husband or wife. It is quite weird to me after thinking about this phrase that people who are single say this term as well when the literal translation of yuh boh is for married couples only. Also, this phrase is said by any gender and any age regardless of what social position they hold in South Korea so it can be said by anyone.
In South Korea, when you first pick up the phone, people answer the phone by saying “yuh boh sae yo?” which in this case would mean “hello, who is this?” Or “hello, how are you?” Also, when you are talking on the phone and you say “yuh boh sae yo” several times repeatedly, it means that you can’t really hear the person in the other line so it would mean something like “hello? hello?! I can’t hear you.” This is where the intonation comes in place with this phrase. Depending on how you say it, in what situation you say it, and with what kind of tone you are saying it with makes this phrase have a completely different meaning. And I mean completely different as the person saying it knows what they mean but the person that hears it doesn’t really know the exact meaning sometimes. You have to almost guess what they mean when they say this phrase to you but to native Korean speakers, it is usually understood without saying what they mean.
Phytochromes consist of a protein, covalently linked to a bilin chromophore. There is two types of them which divides into A and B. They both have PAs domain and GAF domain. The difference is that phytochrome A is etiolated, displays far red and labile light. B is just red. Phytochromes interact heavily with PIFs. PIFs are a subset of transcription factors that negatively regulate photomorphogenesis. COP1 forms a complex in the nuclues, functioning as an E3 ubiquitin ligase, making positive regulators of photomorphogenesis for degradation. There are many processes in this complex for an example, cryptochromes. Haven't learned much of cryptochromes yet though.
- Equilibrium is driven towards product to produce a higher yield of ester in this experiment because the reflux step takes out everything else in the compound and keeps the organic layer itself. By doing reflux 3 times, total of 45 minutes, it gets rid of unnecessary substance in the compound other than the ester. So it is able to produce higher % than 70%.
- Using a sulfuric acid can speed up the reaction. Also, it can act as a dehydrating agent which is good for forcing the equilibrium to be higher yield of ester.
- Carboxylic acid is soluble in water. As it reacts with sodium bicarbonate it removes itself during the extraction phase. So, during extraction of the experiment, most of the excess carboxylic acid is removed.
In this lab, different esters were given to prepare before the lab even began. Given Isopentyl propionate, had to measure alcohol and carboxylic acid precisely that was calculated before the lab began. Then added sulfuric acids about 4 drops mixing them well. Distillation step then followed trapping the water with the help of sand bath to boil. As the vapors condensed and was ready to tip over, kept the lower water phase and got rid of the upper organic phase. For 45 minutes reflux was done. As it cooled down, water and sodium bicarbonate was added to remove the aqueous layer once again. Then calcium chloride was added then took the organic layer into the vial and put it in the capped vial. The ester at the end smelt fruity almost like a pineapple vodka. It was given for an IR spectrum test to prove how it is an ester and not something else. From the esterification IR spectrum graph, it can be proven as an ester since there is a huge curve around 2800-3000 which is only displayed by an ester. 1740-1750 is a carbonyl group that was displayed as an ester. The only thing on this graph that displayed failure was at around 3400 ish, which is where alcohol is displayed. This just means that some alcohol was displayed but it went below half way which means all the acid was gone. The % yield for the given ester was 70.13% which was high.
Use a 5-mL round bottom flask, measure alcohol and carboxylic acid precisely that was calculated in the prelab. Add sulfuric acid (4 drops) with caution and mix them using a clean pipet and expelling them back into the flask. Mixing well is required so it will not result in the concentrated sulfuric acid reacting to form unwanted darkly colored by-products. Add a few boiling chips and go through distillation. Trapping the water is more effective if the side arm points slightly downward when the round block flask with distillation head attached is held in an upright position in a 45-degree angle. Sand bath is then used to boil. Vapors should condense about 1/3 way up the reflux condenser. Overheating can make product and reactants to escape into the atmosphere. Two phases of liquid will collect in the side arm, upper organic phase and lower water phase. Remove water, after the reaction has refluxed for 15 minutes, raise the apparatus from heat and tip it back so that most of the upper phase in the side arm drips. Lower the apparatus back and using sand bath, resume refluxing for 15 minutes, then again lift and tip it back. Reflux for the 3rd and last time to make it 45 minutes total. Then cool it completely for 15 minutes. Take cooled content and use a pipet into a centrifuge containing water (1 mL). Mix well, lower layer to the top, remove the aqueous layer and place it into a beaker. Add sodium bicarbonate (1 mL), mix well, and remove the aqueous layer once again. Add 5 spheres of anhydrous calcium chloride to the liquid and swirl. Using a pipet, take organic layer into a vial and all the spheres should not clump together. Add more spheres if they are clumping together. Using a pipet transfer the liquid to a dry tared capped vial. Smell ester and check the odors of different esters made by classmates. Determine % yield of product, determine and interpret the IR spectrum. For comparison, check the IR spectra of a carboxylic acid, an alcohol, and an ester.
Purpose of this lab is to dehydrate cyclohexanol and synthesizing cyclohexene by taking all that we’ve done so far. These processes include taking the melting points, boiling points, molecular weight densities, and figuring out what the hazardous properties are. By separating and purifying the substance using combination of extraction, distillation, crystallization, chromatography, and more the lab is complete. There are many processes that we learned so far in the lab shown right above, and honestly it was all pretty simple. There are step by step display on what we have to do on the organic chemistry 269 website. Lab reports are fairly simple as well, it just takes some time to complete them. My favorite one is crystallization because different crystals are formed whether it be different color, different weight, and more factors.