Purpose: The purpose of this experiment is to determine the absolute configuration of an unknown chiral secondary alcohol using the competing enantioselective conversion (CEC) method. This method uses both R- and S- enantiomers of a chiral acyl-transfer catalyst called homobenzotetramisole (HBTM), in separate parallel reactions, and thin layer chromatography to identify the stereochemistry of the secondary alcohol, whether it be an R- or S- enantiomer. Quantitative analysis was performed using a program called ImageJ after the appropriate picture was taken of the stained TLC plate. The molecular structure of the unknown alcohol was identified using 1H NMR spectroscopy by matching the hydrogens to the corresponding peak. Theory: The competing enantioselective conversion method uses each enantiomer of a kinetic resolution reagent, in this case R-HBTM and S-HBTM, in separate and parallel reactions, where the stereochemistry of the secondary alcohol is determined by the rate of the reactions. When using the CEC method, the enantiomer of the secondary alcohol will react with one enantiomer of the HBTM acyl-transfer catalyst faster than with the other HBTM enantiomer. The mnemonic that identifies the absolute configuration of the secondary alcohol is as follows: if the reaction is faster with the S-HBTM, then the secondary alcohol has the R-configuration. In contrast, if the reaction is faster with the R-HBTM, then the secondary alcohol has the S-configuration. Thin layer chromatography will be used to discover which enantiomer of HBTM reacts faster with the unknown secondary alcohol. The fast reaction corresponds to a higher Rf spot (the ester) with a greater density and a slower reaction corresponds to a lower Rf spot with high de... ... middle of paper ... ...icted α-methyl-2-naphthalenemethanol. Probably the most obvious clue that corresponded to this secondary alcohol was the seven integrated hydrogens within the aromatic region of 7.5-7.9 ppm. This compound was the only one that had seven hydrogens belonging to naphthalene. The other two secondary alcohols 3-methoxy-α-methylbenzyl alcohol and 4-bromo-α-methylbenzyl alcohol have only four aromatic hydrogens. Conclusion: As a final point, the unknown secondary alcohol α-methyl-2-naphthalenemethanol had the R-configuration since it reacted the fastest with S-HBTM and much slower with R-HBTM. TLC was a qualitative method and ImageJ served as a quantitative method for determining which reaction was the faster esterification. Finally, 1H NMR assisted in identifying the unknown from a finite list of possible alcohols by labeling the hydrogens to the corresponding peaks.
We observed Sowbugs in multiple environments to determine which environment they preferred. The observational chamber was a rectangle box split equally in half. One side of this rectangle was filled with dry sand that had been heated for five minutes by a lamp, and the other side was filled with damp soil that did not receive the lamp heat. We placed each sowbug on the middle boarder of the cool, damp soil and the hot, dry sand. We each chose one sowbug to track, and made a record of its placement each minute for five minutes total. We repeated this process three times. After each repetition, we removed the sowbugs, and replaced them with new sowbugs to observe. After this observation, we shared, and recorded our results. The sowbugs spent
The spots moved 3.8cm, 2.3cm, 2.1cm, 1.8cm, and 2.5 cm, for the methyl benzoate, crude product, mother liquor, recrystallized product, and isomeric mixture, respectively. The Rf values were determined to be.475,.2875,.2625,.225, and.3125, for the methyl benzoate, crude product, mother liquor, recrystallized product, and isomeric mixture, respectively. Electron releasing groups (ERG) activate electrophilic substitution, and make the ortho and para positions negative, and are called ortho para directors. In these reactions, the ortho and para products will be created in a much greater abundance. Electron Withdrawing groups (EWG) make the ortho and para positions positive.
The percent yield of products that was calculated for this reaction was about 81.2%, fairly less pure than the previous product but still decently pure. A carbon NMR and H NMR were produced and used to identify the inequivalent carbons and hydrogens of the product. There were 9 constitutionally inequivalent carbons and potentially 4,5, or 6 constitutionally inequivalent hydrogens. On the H NMR there are 5 peaks, but at a closer inspection of the product, it seems there is only 4 constitutionally inequivalent hydrogens because of the symmetry held by the product and of this H’s. However, expansion of the peaks around the aromatic region on the NMR show 3 peaks, which was suppose to be only 2 peaks. In between the peaks is a peak from the solvent, xylene, that was used, which may account to for this discrepancy in the NMR. Furthermore, the product may have not been fully dissolved or was contaminated, leading to distortion (a splitting) of the peaks. The 2 peaks further down the spectrum were distinguished from two H’s, HF and HE, based off of shielding affects. The HF was closer to the O, so it experienced more of an up field shift than HE. On the C NMR, there are 9 constitutionally inequivalent carbons. A CNMR Peak Position for Typical Functional Group table was consulted to assign the carbons to their corresponding peaks. The carbonyl carbon, C1, is the farthest up field, while the carbons on the benzene ring are in the 120-140 ppm region. The sp3 hybridized carbon, C2 and C3, are the lowest on the spectrum. This reaction verifies the statement, ”Measurements have shown that while naphthalene and benzene both are considered especially stable due to their aromaticity, benzene is significantly more stable than naphthalene.” As seen in the reaction, the benzene ring is left untouched and only the naphthalene is involved in the reaction with maleic
...e 3. Both letters A and B within the structure of trans-9-(2-phenylethenyl) anthracene, that make up the alkene, have a chemical shift between 5-6 ppm and both produce doublets because it has 1 adjacent hydrogen and according to the N + 1 rule that states the number of hydrogens in the adjacent carbon plus 1 provides the splitting pattern and the number of peaks in the split signal, which in this case is a doublet.1 Letters C and D that consist of the aromatic rings, both are multiplets, and have a chemical shift between 7-8 ppm. 1H NMR could be used to differentiate between cis and trans isomers of the product due to J-coupling. When this occurs, trans coupling will be between 11 and 19 Hz and cis coupling will be between 5 and 14 Hz, showing that cis has a slightly lowered coupling constant than trans, and therefore have their respective positions in a product. 2
Discussion and Conclusions: Interpreting these results have concluded that relative reactivity of these three anilines in order of most reactive to least reactive go; Aniline > Anisole > Acetanilide. Aniline, has an NH2 , the most active substituent , and adds to any ortho/para position available on the ring. This data is confirmed with the product obtained, (2,4,6 tribromoaniline, mp of 108-110 C). As for anisole, it has a strongly activating group attached, OMe an alkoxy group, and it added in two of the three available spots, both ortho. The results conclude: (2,4-Dibromoanisol mp 55-58 C ). Acetanilide has a strong activating group attached, acylamino group, but this group is large and the ortho positions are somewhat hindered so the majority of the product obtained added at the para position, results conclude: (p-bromoacetanilide mp 160-165 C). Since all the substituents attached to the aromatic rings were activators the only products able to be obtained were ortho/para products.
Discussion The reaction of (-)-α-phellandrene, 1, and maleic anhydride, 2, gave a Diels-Alder adduct, 4,7-ethanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-5-methyl-8-(1-methylethyl), 3, this reaction gave white crystals in a yield of 2.64 g (37.56%). Both hydrogen and carbon NMR as well as NOESY, COSY and HSQC spectrum were used to prove that 3 had formed. These spectroscopic techniques also aided in the identification of whether the process was attack via the top of bottom face, as well as if this reaction was via the endo or exo process. These possible attacks give rise to four possible products, however, in reality due to steric interactions and electronics only one product is formed.
With all three TLC plates, with varying quantities of hexane and hexane: ethyl acetate, the unknown and the 4- Methoxy-phenol moved the same distance up the plate towards the solvent front. The substitution reaction was successful and lead to the formation of a methoxybenzyl phenol ether with the 4- Methoxy-phenol nucleophile. The data taken from the TLC and the melting points confirmed
As shown in figure 2, the percentage of each isomeric alcohol in the mixture had been determined. The hydrogen atom on the carbon atom with the hydroxyl group appear at around 4.0 ppm for borneol and 3.6 ppm for isoborneol. The product ratio has been determined by integrating the peaks. A ratio of 6:1 for the Isoborneol/borneol ratio was expected and is validated by the calculations shown above, with isoborneol percentage at 83.82% and 16.17% of borneol. A CHCl3 group noted at around 7ppm and a CH2Cl2 at around 3.5ppm.
With the addition of Natron as a herbicide to control weeds, there are concerns that the runoff could affect the growth of other plant life. The purpose of this lab is to test the toxicity of Natron as well as the max dosage that will still allow for beans to grow in the presence of the herbicide; We hope to find out the LD50, the toxicity in comparison to Anubis, as well as the germination rate of exposed the beans. We hypothesized that increased concentration of Natron would lead to a decrease in the germination rate. Our null hypothesis formulated that there would be no correlation between exposure and germination.
After performing the second TLC analysis (Figure 4), it was apparent that the product had purified because of the separation from the starting spot, unlike Figure 3. In addition, there was only spot that could be seen on the final TLC, indicating that only one isomer formed. Since (E,E) is the more stable isomer due to a less steric hindrance relative to the (E,Z) isomer, it can be inferred that (E,E) 1,4-Diphenyl-1,3-butadiene was the sole product. The proton NMR also confirmed that only (E,E) 1,4-Diphenyl-1,3-butadiene formed; based on literature values, the (E,E) isomer has peaks between 6.6-7.0 ppm for vinyl protons and 7.2-7.5 ppm for the phenyl protons. Likewise, the (E,Z) isomer has vinyl proton peaks at 6.2-6.5 ppm and 6.7-6.9 ppm in addition to the phenyl protons. The H NMR in Figure 5 shows multiplets only after 6.5 ppm, again confirming that only (E,E) 1,4-Diphenyl-1,3-butadiene formed. In addition, the coupling constant J of the (E,E) isomer is around 14-15 Hz, while for the (E,Z) isomer it is 11-12 Hz. Based on the NMR in Figure 5, the coupling constant is 15.15 Hz, complementing the production of (E,E)
The Facial Recognition Lab was performed in order to determine whether or not the familiarity effect can be used to influence an individual’s memory. In the lab, ten Most Wanted faces were shown and the subject was asked to study them for an indefinite amount of time. Once they clicked “Next”, they were shown 20 faces in random order, ten of which were from the list they had just studied and ten were new faces. The subject was asked to determine which were new and which were Most Wanted. In theory this should be a relatively easy task, because the subject does not necessarily need to remember that a face was on the previous list, merely that they had seen it before. That it was familiar to them. Thus, on the second day they were shown 20 faces again. If the subject was randomly assigned into the control group, then they saw the Most Wanted faces mixed in with ten new faces. Otherwise they were assigned into the false memory group and were shown the exact same 20 faces they had seen the previous day. The subjects are given a “discrimination index” based on their level of accuracy. The hypothesis is that the control group will perform significantly better (i.e. have a higher discrimination index) than the members of the false memory group. This is because the control group still merely has to recognize a face. Granted they aren’t aware of which group they are in, but to the false memory group, all of the faces will have some degree of familiarity. They must go a step further and actually reconstruct which faces were on the Most Wanted list and which were not.
In this lab 2-methyl-butyn-2-ol is hydrated to 3-hydroxy-3-methyl-2-butanone. This process was preformed by using a strong acid which created an enol, and then the enol tautomerized. Due to this being a terminal alkyne, only one product will be formed. Techniques such as simple distillation, reflux, and gravity filtration were used to produce and separate the product from the mixture that it was in. When performing this lab using only one equivalent of alkyne produced a low percent of 1%. The low yield is a result of using one equivalent instead of two.
23. Official methods of analysis, AOAC, Association of Official Analytical Chemists. Edition 17: AOAC, 2003.
Development of specific ethers has been inactive and fruitful area of investigation in the past few decades.2The strategy of ether catalysis General encompasses synergistic activation of a ethers an electrophile by two or more reactive centers through the combination of a Lewis acid and Lewis base working in concert. Such approach results in high reaction rates and excellent ethers. Hydrogen bonding plays a crucial role in this catalysis. Hydrogen bonding to an electrophile decreases the electron density of this species, activating it toward nucleophilic attack. Recently chemists have begun to appreciate the tremendous potential offered by hydrogen bonding as a tool for electrophile activation in synthetic catalytic systems. In particular, ethers donors have emerged as a broadly applicable class of catalysts for ethers synthesis. An amide unit, the key functional group of peptides, plays an important role in catalyst design and modification. Based on the understanding of different asymmetric catalytic reaction mechanisms, the creation of amide structure-based ether and was realized by rational arrangement of hydrogen-bond networks. According to their model, two water molecules simultaneously establish H-bonds to the carbonyl oxygen of the substrate for optimal transition state stabilization. The concept of explicit double H-bonding activation was no longer restricted to one type of reaction or catalyst, but became a generally applicable principle. The simultaneous donation of two hydrogen bonds has proven to be a highly successful strategy for electrophile activation. Such interactions benefit from increased strength and directionality compared to a single hydrogen bond. Ethers containing double hydrogen bond ethers are capable of directing the assembly of molecules with similar control as
Stereochemistry come to the learning of the relative placement of atoms that form the structure of molecules and their use. An essential subdivision of stereochemistry is the learning of chiral molecules. Stereochemistry is also known as 3D chemistry because the prefix "stereo-" means "three-dimensionality”. The learning of stereochemistry centering on stereoisomers and spans the whole range of organic, inorganic, biological, physical and especially supramolecular chemistry. There is some grandness of stereochemistry. Firstly, is the thalidomide incident. Thalidomide is a medicament drug, first processed in 1957 in Germany, appointed for treating morning illness in pregnant women. The drug was revealed to be teratogenic, causing sincere genetic harm to early embryonic growth and development, leading to limb distortion in babies. Some of the several planned mechanisms of teratogenicity touch on various biological purpose for the (R) - and the (S)-thalidomide enantiomers. In the human body however, thalidomide undergoes racemization whereby justified if only one of the two enantiomers is apply as a drug, the other enantiomer is produced as a outcome of metabolism. Accordingly, it is wrong to state that one of the stereoisomer is harmless while the other is teratogenic. Next, the properties of many drugs rely on their stereochemistry. For information: