Synthesis of Diphenylacetylene

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Anthony Felix
10/27/11
Che12ALR
Synthesis of Diphenylacetylene
Observation of Results:
1,2-dibromo-1,2-diphenylethane| 0.204g|
Diphenylacetylene| 0.087g|
Theoretical yield| 0.107g|
Percent yield| 81.3%|
Melting point range of diphenylacetylene| 57- 60°C|
Average melting point| 58.5°C|
Average literature melting point| 60.0°C|
Percent error of melting point| 2.5%|
Calculations:
Theoretical yield: Limiting reagent (LR) x M.W. (LR) x Mole to Mole ratio x M.W. (product) = Theoretical yield of product. 0.204g 1, 2-dibromo-1, 2-diphenylethane x (1mol 1, 2-dibromo-1, 2-diphenylethane/340.05g 1,2-dibromo-1,2-diphenylethane) x (1mol Diphenylacetylene/1mol 1,2-dibromo-1,2-diphenylethane) x (178.24g Diphenylacetylene/1mol Diphenylacetylene) = 0.107g Diphenylacetylene Percent yield: Actual yield/ Theoretical yield x 100% = Percent yield (0.087g Diphenylacetylene/0.107g Diphenylacetylene) x 100% = 81.31% Average melting point: (start of melting degree + completion of melting degree)/2 = Average melting point Average melting point (59+ 61)/2 = 60°C Average literature melting point Percent error: Absolute value (Abs) (actual yield – theoretical yield)/ theoretical x 100% = percent error Abs. (58.5 – 60)/ 60 x 100 = 2.5%

Scheme of the Reaction (Exp.12a/12b):

Analysis of Results: In this experiment, the compound diphenylacetylene was made by using potassium hydroxide to take the bromine off of the 1, 2-dibromo-1.2-diphenylethane. Pyridinium bromide perbromide was used rather than Br2 due to it being a volatile and highly corrosive substance. Calculate the theoretical yield which was 0.107g of diphenylacetylene. Calculate the percent yield of the reaction which was 81.31%. Calculate the average melting point, so that percent error of the melting point can be produced. The experimental melting point range of diphenylacetylene is 57 - 60°C, and the literature value range of diphenylacetylene is 59 - 61°C. The averages of each of the...
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