Diphenylethane Percent Yield
The percent yield of meso-1,2-dibromo-1,2-diphenylethane was calculated to be 66.36% and with a melting point of 235.1°C. Therefore, it can be concluded that this experiment was successfully conducted as the percent yield obtained is only 33.64% off from the equilibrium point, and because the melting point met the literature value.
The percent yield for the product was less than 100%, indicating that were experimental errors, such as an undesirable side reaction, or more likely, an incomplete reaction and loss of product. This may have occurred with incorrect filtering, evaporating and transferring of material. Also, some product may have been lost when collecting product for vacuum filtration, as very little acetic acid was used to remove …show more content…
the yellow impurity from the round bottom flask.
In terms of the melting point, the structure of the product explains why the value is quite high. Meso-1,2-dibromo-1,2-diphenylethane contains two bromine molecules, which are halogens, to help increase the melting point and also to create an asymmetrical shape. This asymmetrical shape contributes to the presence of dipoles, which in result, furthers the increase of the melting point.
In this experiment, a reflux condenser was used for the reaction to take place. In order to determine if the reaction was complete, a comparative TLC was conducted. The mixture was spotted on the plate with trans-stilbene and 1,2-dibromo-1,2-diphernlenthane. Since the reaction mixture matched the 1,2-dibromo-1,2-diphernlenthane result, it was concluded that the reaction was complete and was ready to be filtered. Furthermore, the standard trans-stilbene material travelled further up the plate, indicating that the product has a lower dipole and therefore is less polar than the starting material.
Part 2 – Alkyne Synthesis
The percent yield of diphenylacetylene was calculated to be 39.45%, with a melting point of 60°C and a purity percentage of 1491.70%.
Since the percent yield is not 100%, it can be concluded that there are some sources of error that exist for this experiment, such as product being lost and/or the reactants not making it to products. Moreover, the melting point matches the theoretical value, thus the final product formed was successfully diphenylacetylene. However, the percent purity of the reaction is completely out of proportion, hence there are many errors that took place during the UV-vis analysis.
An adequate percent yield was obtained from this experiment, but the relativity low value can be explained by the loss of product transferring and filtering the product. Furthermore, there may have been incomplete crystallization when the reaction mixture was cooled down to room temperature and then chilled in an ice bath. The crystals may have been purified and then filtered with vacuum filtration before all the crystals were formed, which decreased the amount of product …show more content…
collected.
In terms of the melting point, structure is important. The structure of diphenylacetylene contains two phenyl groups and a triple bond, making the structure linear. The presence of benzenes does not increase the intermolecular interactions, thus not increasing melting point either. Furthermore, the linear structure and symmetry of the compound cancels out any dipoles that exist in the molecule making the melting point relatively low. However, since diphenylacetylene was synthesized from meso-1,2-dibromo-1,2-diphenylethane, which has a high melting point, the starting material had to be boiled between 120°C-130°C in order to eliminate the bromine molecules. The solvent used in this process was triethylene glycol as the second elimination reaction of H-Br from the alkene required more energy to eliminate the bromine, which is due to the present of a double bond.
In order to determine if the reaction was complete before moving on to the cooling of the mixture, a comparative TLC was conducted. This helped to determine if there was any starting material left in the mixture or not. The reference material used for this comparison was 1,2-diphenylacetate. Since the spot of the product mixture appeared lower than the standard dot, it was concluded that the reaction was complete and ready for the next step.
For percent purity, the synthesized product has an incredibly high percentage. The absorbance of the product was determined to be 10, which is extremely elevated. This skewed the results as purity depends on the absorbance and the concentration. The absorbance of light is directly proportional to the number of molecules it can interact with. The source of error for this absorbance and UV-vis analysis is because of a mistake in procedure. Instead of adding ethanol to the 3 volumetric flasks for a serial dilution, distilled water was added instead. This altered all the results, thus making the UV-vis analysis useless in helping to determine the final product. Ethanol is used in this procedure because it absorbs light very weakly at most wavelengths. Also, the solvent’s polarity and pH affects the absorption, so adding water to the three dilutions created a huge experimental error. However, it is known that since the ε for the sample is greater than the standard value, that the product at the given concentration is larger than the theoretical. Furthermore, by conducting the wrong procedure, the series of dilutions were not able to give a correct final concentration as well. This contributed to an altered absorbance, comparison for characterization and identification as well as determination of percent purity.
Conclusion
The purpose of experiment 6 was to conduct various producers and use different techniques to synthesize an alkene to an alkane, and then an alkane to an alkyne.
The synthesis of meso-1,2-dibromo-1,2-diphenylethane was successful as the final product of the experiment had the same physical properties of the theoretical properties, which were determined by TLC and melting point. The synthesis of diphenylacetylene was also successful, as TLC and the melting point both proved its identity, however the UV-vis analysis went awry due to a procedural mistake, making the analysis unusable. The most important learning outcome of Experiment 6 was understanding SN2 and E2
mechanisms.
The percent yield for the product was less than 100%, indicating that were experimental errors, such as an undesirable side reaction, or more likely, an incomplete reaction and loss of product. This may have occurred with incorrect filtering, evaporating and transferring of material. Also, some product may have been lost when collecting product for vacuum filtration, as very little acetic acid was used to remove …show more content…
the yellow impurity from the round bottom flask.
In terms of the melting point, the structure of the product explains why the value is quite high. Meso-1,2-dibromo-1,2-diphenylethane contains two bromine molecules, which are halogens, to help increase the melting point and also to create an asymmetrical shape. This asymmetrical shape contributes to the presence of dipoles, which in result, furthers the increase of the melting point.
In this experiment, a reflux condenser was used for the reaction to take place. In order to determine if the reaction was complete, a comparative TLC was conducted. The mixture was spotted on the plate with trans-stilbene and 1,2-dibromo-1,2-diphernlenthane. Since the reaction mixture matched the 1,2-dibromo-1,2-diphernlenthane result, it was concluded that the reaction was complete and was ready to be filtered. Furthermore, the standard trans-stilbene material travelled further up the plate, indicating that the product has a lower dipole and therefore is less polar than the starting material.
Part 2 – Alkyne Synthesis
The percent yield of diphenylacetylene was calculated to be 39.45%, with a melting point of 60°C and a purity percentage of 1491.70%.
Since the percent yield is not 100%, it can be concluded that there are some sources of error that exist for this experiment, such as product being lost and/or the reactants not making it to products. Moreover, the melting point matches the theoretical value, thus the final product formed was successfully diphenylacetylene. However, the percent purity of the reaction is completely out of proportion, hence there are many errors that took place during the UV-vis analysis.
An adequate percent yield was obtained from this experiment, but the relativity low value can be explained by the loss of product transferring and filtering the product. Furthermore, there may have been incomplete crystallization when the reaction mixture was cooled down to room temperature and then chilled in an ice bath. The crystals may have been purified and then filtered with vacuum filtration before all the crystals were formed, which decreased the amount of product …show more content…
collected.
In terms of the melting point, structure is important. The structure of diphenylacetylene contains two phenyl groups and a triple bond, making the structure linear. The presence of benzenes does not increase the intermolecular interactions, thus not increasing melting point either. Furthermore, the linear structure and symmetry of the compound cancels out any dipoles that exist in the molecule making the melting point relatively low. However, since diphenylacetylene was synthesized from meso-1,2-dibromo-1,2-diphenylethane, which has a high melting point, the starting material had to be boiled between 120°C-130°C in order to eliminate the bromine molecules. The solvent used in this process was triethylene glycol as the second elimination reaction of H-Br from the alkene required more energy to eliminate the bromine, which is due to the present of a double bond.
In order to determine if the reaction was complete before moving on to the cooling of the mixture, a comparative TLC was conducted. This helped to determine if there was any starting material left in the mixture or not. The reference material used for this comparison was 1,2-diphenylacetate. Since the spot of the product mixture appeared lower than the standard dot, it was concluded that the reaction was complete and ready for the next step.
For percent purity, the synthesized product has an incredibly high percentage. The absorbance of the product was determined to be 10, which is extremely elevated. This skewed the results as purity depends on the absorbance and the concentration. The absorbance of light is directly proportional to the number of molecules it can interact with. The source of error for this absorbance and UV-vis analysis is because of a mistake in procedure. Instead of adding ethanol to the 3 volumetric flasks for a serial dilution, distilled water was added instead. This altered all the results, thus making the UV-vis analysis useless in helping to determine the final product. Ethanol is used in this procedure because it absorbs light very weakly at most wavelengths. Also, the solvent’s polarity and pH affects the absorption, so adding water to the three dilutions created a huge experimental error. However, it is known that since the ε for the sample is greater than the standard value, that the product at the given concentration is larger than the theoretical. Furthermore, by conducting the wrong procedure, the series of dilutions were not able to give a correct final concentration as well. This contributed to an altered absorbance, comparison for characterization and identification as well as determination of percent purity.
Conclusion
The purpose of experiment 6 was to conduct various producers and use different techniques to synthesize an alkene to an alkane, and then an alkane to an alkyne.
The synthesis of meso-1,2-dibromo-1,2-diphenylethane was successful as the final product of the experiment had the same physical properties of the theoretical properties, which were determined by TLC and melting point. The synthesis of diphenylacetylene was also successful, as TLC and the melting point both proved its identity, however the UV-vis analysis went awry due to a procedural mistake, making the analysis unusable. The most important learning outcome of Experiment 6 was understanding SN2 and E2
mechanisms.