Dibromo-3-Phenylpropanoic Acid Synthesis
In this experiment, the stereochemistry of 2,3-dibromo-3-phenylpropanoic was found to determine syn or anti addition of bromines. The melting point was 199-203°C and the NMR J values angle is at 167 which both prove the erythro-2,3-dibromo-3-phenylpropanoic.
Determination of the Stereochemistry of 2,3-dibromo-3-phenylpropanoic acid.
Introduction
The purpose of this experiment was to determine the mechanism of the reaction of trans-cinnamic acid with the addition of bromines to 2,3-dibromo-3-phenylpropanoic acid. An addition of bromine was added to trans-cinnamic acid and it is necessary to determine whether the intermediates were syn or anti addition or a mixture of them both to find the stereochemistry of the final product. The final product …show more content…
M. Roof, William J. Winter, and Paul D. Bartlett, they studied the kinetics of the reaction and found that syn isomer ends with serious compression issues on its bridge. They concluded that if any mechanism had a late transition state then syn the syn isomer would occur because there would be an easy access path to the carbon . There are several ways that the reaction can go syn or anti, but syn addition will only occur if aided. Anti addition occurs when the carbon-carbon bond undergoes rotation and syn addition occurs when the intermediate collapses providing the means for a carbocation to form.
Methodology
The general Procedure found in Lehman was used for this experiment. A variance in the procedure is that an NMR will also be used to analyze the results. The PCSpartanPlus molecular modeling system was used on Tuesday, January 17th, to calculate the frequency and the equilibrium geometry.
Table of Reagents
Reagents Amount Needed (moles) Amount needed (g or mL)
Trans-cinnamic acid 0.01 moles 1.482 g
Glacial acetic acid 9.541 moles 6.0 mL or 6.29 g
1.25M bromine solution 0.1025 moles 16.38 g
Results
Bromine Addition Table
Portion Time Color Amount …show more content…
484.181-472.363=11.8 Hz and 442.285-429.980=12.31 Hz. From the Karplus graph, the angle is estimated at 167 which is the erythro-2,3-dibromo-3-phenylpropanoic.
Karplus Equation
Conclusion
For the syn addition of the bromines the mechanism would be the following: For the anti addition of the bromines the mechanism would be the following: The final product was be erythro-2,3-dibromo-3-phenylpropanoic. It went through syn addition as shown by the mechanism because the molecule is more stable with the carbocation next to the benzene ring than it is with the bromine triangle. The data is backed up by the J values corresponding to the angles at 167 which was the erythro-2,3-dibromo-3-phenylpropanoic as well as with the melting point data which was only a few degrees off of the literature value for erythro-2,3-dibromo-3-phenylpropanoic and around a hundred degrees off of the alternate
Determination of the Stereochemistry of 2,3-dibromo-3-phenylpropanoic acid.
Introduction
The purpose of this experiment was to determine the mechanism of the reaction of trans-cinnamic acid with the addition of bromines to 2,3-dibromo-3-phenylpropanoic acid. An addition of bromine was added to trans-cinnamic acid and it is necessary to determine whether the intermediates were syn or anti addition or a mixture of them both to find the stereochemistry of the final product. The final product …show more content…
M. Roof, William J. Winter, and Paul D. Bartlett, they studied the kinetics of the reaction and found that syn isomer ends with serious compression issues on its bridge. They concluded that if any mechanism had a late transition state then syn the syn isomer would occur because there would be an easy access path to the carbon . There are several ways that the reaction can go syn or anti, but syn addition will only occur if aided. Anti addition occurs when the carbon-carbon bond undergoes rotation and syn addition occurs when the intermediate collapses providing the means for a carbocation to form.
Methodology
The general Procedure found in Lehman was used for this experiment. A variance in the procedure is that an NMR will also be used to analyze the results. The PCSpartanPlus molecular modeling system was used on Tuesday, January 17th, to calculate the frequency and the equilibrium geometry.
Table of Reagents
Reagents Amount Needed (moles) Amount needed (g or mL)
Trans-cinnamic acid 0.01 moles 1.482 g
Glacial acetic acid 9.541 moles 6.0 mL or 6.29 g
1.25M bromine solution 0.1025 moles 16.38 g
Results
Bromine Addition Table
Portion Time Color Amount …show more content…
484.181-472.363=11.8 Hz and 442.285-429.980=12.31 Hz. From the Karplus graph, the angle is estimated at 167 which is the erythro-2,3-dibromo-3-phenylpropanoic.
Karplus Equation
Conclusion
For the syn addition of the bromines the mechanism would be the following: For the anti addition of the bromines the mechanism would be the following: The final product was be erythro-2,3-dibromo-3-phenylpropanoic. It went through syn addition as shown by the mechanism because the molecule is more stable with the carbocation next to the benzene ring than it is with the bromine triangle. The data is backed up by the J values corresponding to the angles at 167 which was the erythro-2,3-dibromo-3-phenylpropanoic as well as with the melting point data which was only a few degrees off of the literature value for erythro-2,3-dibromo-3-phenylpropanoic and around a hundred degrees off of the alternate