Purpose/Introduction What reaction was conducted in this experiment and with what reagents? Was there a reason for this reaction beyond just synthesis of product(s)? What techniques were used to purify and identify the product(s) of the reaction? The purpose of this experiment was to investigate the bromination of trans-cinnamic acid and determine what the isolated products tells us about the possible mechanism. The stereochemistry of the product results from either a syn or anti addition of Br2 to the alkene. Recrystallization using ethanol and water solvent mixture was used to purify the crude product and melting point was implemented in order to see which products were synthesized. The syn addition products (2S, 3S- and 2R, 3R) 2,3-dibromo-3-phenylpropanoic acid have a melting range of 93.5-95 ᵒC. The anti addition products (2S, 3R- and 2R, 3S) 2,3-dibromo-3-phenylpropanoic acid have a melting range of 202-204 ᵒC. Theory: Experiment-Specific Questions: In this experiment you were asked to present three possible mechanisms. Describe those mechanisms here. How will the bromination of trans-cinnamic acid allow you to distinguish between the three possibilities? What would you expect to find in your data in each scenario? The three possible mechanisms are syn addition, anti addition, and both syn and anti addition. The syn addition is where both bromine atoms are added to the same face of the alkene. The anti addition is where both bromine atoms are added to opposite sides of the alkene. The syn addition mechanism is a concerted reaction since all bonds are made and broken at the same time. The pi bond from the C=C double bond is given to one of the bromine atoms. The Br–Br bond is broken and one of the bromine atoms acqu... ... middle of paper ... ...ge of 202-204 ᵒC. Therefore, the concluded mechanism was anti addition of bromine to trans-cinnamic acid resulting in (2S, 3R- and 2R, 3S) 2,3-dibromo-3-phenylpropanoic acid (pair of enantiomers) based off the key pieces of data derived from the melting point experimentation. If this experiment were to be conducted again, some possible changes can be to use a greater mass of reagents. This can help lower the chance in having the unreacted substances stuck to the sides of the glassware, consequently lowering the yield. Moreover, the addition of Br2 ideally should be from a fresh batch and free of contaminants; this goes the same for trans cinnamic acid. Having all reagents react in optimal conditions is what further increases the probability of obtaining a higher yield in recrystallized product and a melting point closer to that of the expected product.
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
2-ethyl-1,3-hexanediol. The molecular weight of this compound is 146.2g/mol. It is converted into 2-ethyl-1-hydroxyhexan-3-one. This compounds molecular weight is 144.2g/mol. This gives a theoretical yield of .63 grams. My actual yield was .42 grams. Therefore, my percent yield was 67%. This was one of my highest yields yet. I felt that this was a good yield because part of this experiment is an equilibrium reaction. Hypochlorite must be used in excess to push the reaction to the right. Also, there were better ways to do this experiment where higher yields could have been produced. For example PCC could have been used. However, because of its toxic properties, its use is restricted. The purpose of this experiment was to determine which of the 3 compounds was formed from the starting material. The third compound was the oxidation of both alcohols. This could not have been my product because of the results of my IR. I had a broad large absorption is the range of 3200 to 3500 wavenumbers. This indicates the presence of an alcohol. If my compound had been fully oxidized then there would be no such alcohol present. Also, because of my IR, I know that my compound was one of the other 2 compounds because of the strong sharp absorption at 1705 wavenumbers. This indicates the presence of a carbonyl. Also, my 2,4-DNP test was positive. Therefore I had to prove which of the two compounds my final product was. The first was the oxidation of the primary alcohol, forming an aldehyde and a secondary alcohol. This could not have been my product because the Tollen’s test. My test was negative indicating no such aldehyde. Also, the textbook states that aldehydes show 2 characteristic absorption’s in the range of 2720-2820 wavenumbers. No such absorption’s were present in my sample. Therefore my final product was the oxidation of the secondary alcohol. My final product had a primary alcohol and a secondary ketone
In the experiment “ Talking to plants “ from Mythbusters, potential problems include the use of greenhouses with no sound insulation, a non-homogeneous location and the use of only one specie to infer on a population. In another scientific study, researchers chose to use “ a noiseless growth chamber to prevent any effects from extraneous noise “ and the use “ growth chambers under continuous light at 28 c and 65-75% relative humidity “ in order to maintain a homogeneous location for all plants during the experiment (Jeong et al., 2008) . This helped further explain the findings because with the use of noiseless chambers you can assure that the only noise that the plant was receiving was the one given in the treatment and a valid conclusion
Results: Through a melting point reading, it was determined that the product obtained was 2,4-Dibromoanisol mp 55-58 C. The products obtained by my partners, were determined to be: (p-bromoacetanilide mp 160-165 C) and (2,4,6 tribromoaniline, mp of 108-110 C) respectively.
Objective: The objective of the experiment is to determine what factors cause a change in speed of a reaction. It is also to decide if the change is correlated with the balanced equation of the reaction and, therefore, predictable. To obtain a reaction, permanganate, MnO_4^(1-), must be reduced by oxalic acid, C_2 O_4 H_2. The balanced equation for the reaction is:
During a time of moral and civil unrest, Herbert Hoover, the 31st president of the United States attempted a “great social and economic experiment” that led to the prohibition of alcohol. On January 19, 1920 the US enacted the 18th amendment and set forth into the Prohibition Era. This amendment outlawed the “manufacture, sale or transportation of intoxicating liquors”. Americans later coined the term the “noble experiment” to describe this event in our national history. Unfortunately, the events that took place during this decade were anything but noble. After much backlash and dire consequence, President Theodore Roosevelt would end prohibition by proposing the 21st Amendment to the Constitution that appealed
The percentage yield gained was 70% from the Fischer Esterification reaction, which evaluates to be a good production of yield produced as the reaction is known to be reversible where conditions such as the concentration of the reactants, pressure and temperature could affect the extent of the reaction from performing. These white crystalline crystals were tested for impurity by conducting a melting point analysis and taking spectrospic data such as the IR spectra, HNMR and CNMR to confirm the identification of the product. These spectrospic methods and melting point analysis confirmed the white crystalline crystals were benzocaine.
When 1-bromobutane is reacted with potassium t-butoxide there is only one product formed, 1-butene. This is because the halide is on a primary carbon thus producing only one product.
Then the reaction tube was capped but not tightly. The tube then was placed in a sand bath reflux to heat it until a brown color was formed. Then the tube was taken out of the sand bath and allowed to cool to room temperature. Then the tube was shaken until a formation of a white solid at the bottom of the tube. After formation of the white solid, diphenyl ether (2 mL) was added to the solution and heated until the white solid was completely dissolved in the solution. After heating, the tube was cooled to room temperature. Then toluene (2 mL) was added to the solution. The tube was then placed in an ice bath. Then the solution was filtered via vacuum filtration, and there was a formation of a white solid. Then the product was dried and weighed. The Final product was hexaphenylbenzene (0.094 g, 0.176 mmol,
Enantiomers, a type of isomer, are non-superimposable, mirror images of each other. Diasteriomers, another type of isomer, are non-superimposable, non-mirror images of each other. Dimethyl maleate and dimethyl fumarate are diasteriomers, as they are not mirror images but instead vary in the orientation of the carbomethoxy groups around the double bond. Dimethyl maleate is the cis-isomer because both groups are on the same side and dimethyl fumarate is the trans-isomer because the two groups are on opposite sides. A bromine free radical mechanism was required for this conversion. First, energy from light is required to create two bromine free radicals from Br2. Then one of the free radicals attacks the double bond in dimethyl maleate, breaking it and creating a carbon radical on the other carbon. The bond then rotates and reforms, freeing the bromine radical and creating the trans-isomer, dimethyl fumarate. Bromine in this reaction is acting as a catalyst in this reaction and then cyclohexane is added at the end to neutralize the bromine free radicals. The activation reaction of the radical reaction is lower than the activation energy of the addition reaction, which is why it occurred more quickly. This reaction was successful because the percent yield was 67.1%, which is greater that 65%. It also demonstrated the expected principles, as the reaction did not occur without the presence of both light and bromine. The dimethyl fumarate had a measured boiling point of 100C to 103C, which is extremely close to the expected boiling point of 102C to
n hypothesis of the experiment is that the group containing four members will perform better than the group containing two members. This is the foundation from which we have conducted our experiment.
For this experiment we have to use physical methods to separate the reaction mixture from the liquid. The physical methods that were used are filtration and evaporation. Filtration is the separation of a solid from a liquid by passing the liquid through a porous material, such as filter paper. Evaporation is when you place the residue and the damp filter paper into a drying oven to draw moisture from it by heating it and leaving only the dry solid portion behind (Lab Guide pg. 33.).
A condenser and heat reflux was used to prevent reagents from escaping. Then the solid product was vacuum filtered. The product was recrystallized to purify it and the unknown
The reaction mixture was then cooled down to room temperature and was not disturbed during the cooling process. Crystals were formed and then the beaker was placed into an ice-water bath until the liquid had thickened into a semi-solid