Disproportionation Reaction Lab Report

The literature values of erythro-2,3-dibromo-3-phenylpropanoic acid and threo-2,3-dibromo-3-phenylpropanoic acid were provided in the laboratory experiment text. Erythro-2,3-dibromo-phenylpropanoic acid held a melting point of 204°C, while threo-2,3-dibromo-3-phenylpropanoic acid held a melting point of 95°C. These two products had vastly different melting point values, which made it clear to observe the product created at the end of the experiment. Once the product was determined due to comparison of melting points, the stereochemistry could be

In this experiment, meso-stilbene dibromide was used to produce diphenylacetylene through two sequential dehydrohalogenations. The first part is a concerted E2 mechanism, where the reactant is deprotonated at the beta carbon from the halide ion that will be leaving. This creates a transition state where the leaving hydrogen and halide are anti-periplanar with each other, meaning that they are at a 180° angle in relation to one another. This reaction is caused by a base—in this case, potassium hydroxide—and produces a haloalkene, or vinyl halide. Potassium hydroxide was only added to reaction when needed, as

What essentially happens in these reactions is that first, light breaks the bond between two bromine atoms, from a

Science A CH1HP H Unit Chemistry C1 Chemistry Unit Chemistry C1 Monday 10 June 2013 1.30 pm to 2.30 pm Mark 1 2 3 4 5 6 7 TOTAL For this paper you must have:  a ruler  the Chemistry Data Sheet (enclosed).

CHE341Homework Assignment #10Due:Monday16Novemberat6:00PM1.Aunimoleculargas-phasereactionX→Yis activated with collisions by an unreactivecollision partner Bwith the following mechanism:X+Bk1k−1⎯→⎯⎯←⎯⎯⎯X*+B,X*k2⎯→⎯Y,has a rate that follows the effective rate equationdY[]dt=kuniX[]. (a) Apply the steady state approximation (SSA) to determine an algebraicexpression forkuniin terms terms of the rate constantsk1,k–1andk2as well as [B]. (b)Discusshow the rate law changes in the limit of large and small [B].2.Dissociation of ethane into methyl radicalsfollowsfirst-order kinetics with ArrheniusparametersA=2.50×1016s–1andEa=367.6kJ mol–1. Calculate the Gibbs energy ofactivation, the entropy of activation and the enthalpy of activation at500 K.3.

Infrared spectral analysis is consistent with the proposed structure and with other reported analyses [11-24]. The spectra all show bands characteristic of both reactants and new bands for the product assigned to the

For this experiment, a dehydrobromination was performed on a meso-stilbene dibromide to form an alkyne. The meso-dibromostilbene was converted into diphenylacetylene, an alkyne, through two E2 elimination reactions. The dibromostilbene reacted with a strong base, potassium hydroxide, at a very high temperature. The hydroxide, from KOH, deprotonated one of the aliphatic hydrogen atoms or protons which formed an alkene and broke one of the C-Br bonds releasing the bromine. This process does not take much energy to remove one of the H-Br. This process was completed twice, and the second C-Br bond was broken, and an alkyne formed. This process was more difficult due to the rotation needed to perform the initial elimination. The elevated temperature

Procedure: Refer to pages 67-76 of General Chemistry 1210: General Chemistry Laboratory Manual by the Department of Chemistry, The Ohio State University, Hayden-McNeil Publishing, 2016.

CHE 133 Experiment 3, General Chemistry II Lab, Spring Quarter 2014-2015, DePaul University. [Online] https://www.d2l.depaul.edu (accessed April 25, 2015)

Determining how a mechanism comes to be is crucial as a scientist and arriving to conclusions is a crucial component which lead to examining and determining which mechanism takes place when two or more substrates are made to react. At the end of the experiment a mechanism was determined based on the purified product’s melting point. This was accomplished by having the reaction take place but also through acquiring the melting point and comparing the number to the melting point which was already established by the scientific community. (Q1) When 0.252 g of trans-cinnamic acid was mixed in 2.5 mL glacial acetic acid and 0.434g pyridinium tribromide was added, the resulting product reflects an addition reaction. In general, reactions take place to achieve its lowest Gibb’s free energy because it’s at

Olmsted, John III; Williams, Greg; Burk, Robert C. Chemistry, 1st Canadian ed.; John Wiley and Sons Ltd: Mississauga, Canada, 2010, pp 399 - 406

DPPH radical scavenging activity The radical scavenging activity of the newly synthesized compounds were measured by DPPH (2,2,-diphenyl-1-picrylhydrazyl radical) method.[31] To 4 mL of 0.004% w/v methanol solution of DPPH, 1mL of various concentrations of the test compounds (75 and 100 µg/mL) in methanol were added. The test tubes were incubated for 30 min at room temperature in dark; the absorbance of the test sample was recorded in UV spectrophotometer at 517 nm. Ascorbic acid was used as the standard. Tests were carried out in triplicate and mean of the values were calculated and summarized in Table S2.

After determining the rate law, the activation energy was determined by changing the temperature at which the reaction took place. Using the rate constants calculated at the two different temperatures, the activation energy was calculated. It was found, experimentally through the method of

The addition of OH radical to β-carotene is slightly less thermodynamically favourable than the H-atom abstraction reactions. The free energy of the OH-radical addition reactions to the 15E and 15Z isomers is illustrated in Figure 5 and the thermochemistry of the reactions calculated at various levels are summarized in Table 4. The OH radical addition reactions are more entropy driven in the solvent medium than in the gas phase. The OH-radical adduct resulting from the 15Z isomer is more exergonic by ~ 15 kJ/mol than the OH-radical adduct at the 15E isomer in all the three phases studied. A previous study on the addition of NO2 radical to C5-position of β-carotene reported the reaction to be endergonic in the polar and non-polar solvents.13 The exergonicity of the OH-radical additions to β-carotene is attributed to the high reactivity of OH radical compared to that of NO2 radical.

4) Try and propose a mechanism for the reaction using the orders of reaction taking into account the iodine, propanone and sulphuric acid.