1. The major goal of this paper is to examine the electronic effects of how substituent groups impact the hydroboration of the substituted styrene molecules. The scientists focused mainly on understanding the positioning in which the boron-hydrogen moiety was added to the carbon-carbon double bond.
2. The purpose of the experiments reported in Table 1 was to determine the reproducibility of the α and β alcohol distribution as a result of the hydroboration of styrene. This was achieved through manipulating the variations of the hydride/styrene ratios. The results indicated a 19:81 α to β ratio that showed consistency with the reported 20:80 ratio. The results in Table 1 deduced that there was no significant change through the distribution of
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The presence of ethylbenzene complicated the analysis of results because the increased appearance of ethylbenzenes as a product of o- and p-trifluromethylstyrene and m-nitrostyrene was inversely related with a decrease in the yield of α alcohol. The author concluded that the product of ethylbenzene was due to competing reactions taking place.
4. The α hydrogen in p-nitrotoluene would be more acidic than the α hydrogen in m-nitrotoluene because the conjugate base of p-nitrotoluene has more resonance allowing for a greater delocalization of the charge and more stability. The more stable a molecule is the faster it will react when compared to a less stable molecule and thus the α hydrogen in p-nitrotoluene is more likely to donate its
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With increased amounts of boron distribution in the α position would come from a greater desire for the transition state III.
The p-CF isomer has the highest α-boron distribution due to the highly electronegative CF substituent. The tri-fluoro group connected to the carbon would stabilize the partial negative of the α carbon in transition state III through induction. Fluorine is more electronegative than chlorine, so fluorine would have a greater inductive force.
The p-CH3O isomer would favor transition state II. This is because the partial positive of α carbon in transition state II could be stabilized through resonance.
The styrene molecule H would favor transition state II because the molecule is stabilized through hyperconjugation and resonance. Transition state III is not preferred because the partial positive would have less hyperconjugation and the boron would cause steric strain.
The p-Cl isomer would have a higher α boron distribution. The chlorine acts as an electron withdrawing substituent. This would stabilize the partial negative on the α carbon in transition state
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...
The electrophile is positively charged, so it will not go to the ortho and para positions, but to the meta positions in greater abundance. Therefore, the majority of EWGs (with the exception of halogens) are meta directors. In this experiment, a meta director is used. If the product added to the ortho or para positions produces a carbocation intermediate that has a positive charge on a carbon that is directly touching the EWG. This carbocation intermediate has more energy, and is therefore less stable.
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
The 1H NMR spectrum shows that there are 18 protons in 11 different proton environments. This fits with the Diels-Alder reaction taking place a...
This experiment was divided into two main steps. The first step was the addition of bromine to trans-stilbene. Trans-stilbene was weighted out 2.00g, 0.0111mol and mixed with 40ml of glacial acetic acid in 100ml Erlenmeyer flask on a hot bath. Pyridinium hydrobromide perbromide of 4.00g, 0.0125mol was added carefully into the flask.
Benzyl bromide, an unknown nucleophile and sodium hydroxide was synthesized to form a benzyl ether product. This product was purified and analyzed to find the unknown in the compound. A condenser and heat reflux was used to prevent reagents from escaping. Then the solid product was vacuum filtered.
Staudt, Maureen, and Michael Stranz, eds. General Chemistry for Engineering and Science II. Mason,Ohio: Cengage Learning, 2012. Print.
The purpose of this lab was to determine what vegetation was present above and below the water’s surface and to observe the water visibility depth. We took sampling data from the two different lakes at Noxubee Refuge. The two lakes were Bluff Lake and Loakfoma Lake. The Bluff lake consists of 800 acres of the Noxubee Refuge, and Loakfoma Lake consists of 400 acres (About the Refuge). Many different wildlife species are present at these two lakes. The wildlife includes migratory waterfowl, shoreline birds, and alligators. We observed all three of these wildlife species while collecting data. Along with the wildlife, there are many different plant species to observe. The plant species consist of upland species and bottomland species.
...rivate and taking into account there boiling point and volatility the Gc retention time will increase, in accordance to the chain going up, so in this case the pentyl derivative would go first then the butyl derivative.
The good symmetry in para-xylene, makes all of the hydrogen atoms equivalent. As such, if any hydrogen atom is substituted with an alkyl group, it leads to a similar alkylated product. The reaction is electrophilic substitution in which
The pressure exerted by any gas or mixture of gasses in an enclosed space is directly proportional to the number of atoms or molecules of gas regardless of their size or molecular mass. Reference to the above reaction shows that, as the reaction moves to the right the number of molecules and hence the pressure decreases. Therefore the reaction moving to the right (i.e. towards the product required) is favoured by an increase in pressure.
The chemical history of trinitrotoluene, other wise known as TNT, Trotyl, 2,4,6-Trinitrotoluene, 2-Methyl-1,3,5-trinitrobenzene, and C7H5N3O6, was first made in 1863 by Joseph Wilbrand, a German chemist born in Gießen, or Giessen, on August 22, 1839 and died on June 22, 1906 (he was 66 and two months from turning 67). at the age of around 25. He had created TNT, or trinitrotoluene by putting toluene, which is C7H8, through the process of nitration. 130 mg/L TNT is soluble in water at 20˚C. The steam pressure of it, at 20˚C, is 150 Pa to 600 Pa (about 0.001 atm. to about 0.006 atm.). When the TNT explodes, it travels 6700 to 7000 (usually meters per second, at a density of 1.6 grams per centimeter cubed. In a Lead (Symbol: Pb) block test, TNT’s result is 300 milliliters /10 grams. The sensitivity to impact is 15 newton meters, the same as about 11 pound
...n initiated with Sn(Oct)2 were studied by conducting various reactions incorporating various ratio and amount of reagents, co-initiator and trapping agents. Furthermore, reaction kinetics were monitored and intermediate /trapped compounds were isolated and identified. The results indicated that propagation did not proceed as cationic polymerization. Reaction was co-initiated by alcohol or alkoxide compound and Sn was attached to the propagating group.
In the petroleum refining process, nitrobenzene is mostly used as solvent in the production of acetate and ethers