Synthesis of Diphenylacetylene

Anthony Felix 10/27/11 Che12ALR Synthesis of Diphenylacetylene placard of Results 1,2-dibromo-1,2-diphenylethane 0. 204g Diphenylacetylene 0. 087g Theoretical output 0. 107g part issue 81. 3% Melting pourboire range of diphenylacetylene 57- 60C Average dissolve signify 58. 5C Average literature warming record 60. 0C Percent misconduct 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. 5g 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 = A verage melting point Average melting point (59+ 61)/2 = 60C Average literature melting point Percent erroneous belief despotic value (Abs) (actual yield theoretical yield)/ theoretical x 100% = percent error Abs. 58. 5 60)/ 60 x 100 = 2. 5% design of the Reaction (Exp. 12a/12b) Analysis of Results In this experiment, the compound diphenylacetylene was made by use potassium hydroxide to take the bromine off of the 1, 2-dibromo-1. 2-diphenylethane. Pyridinium bromide perbromide was use rather than Br2 due to it being a volatile and highly acerb 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 60C, and the literature value range of diphenylacetylene is 59 61C. The averages of each of the melting points respectively are 58. 5C and 60C, so the percent error is 2. 5%. Some error that could have occurred was that some of the product was left in the round goat and could not be taken out to be dried. The error in the melting point could have occurred from either 1,2-dibromo-1,2-diphenylethane or potassium hydroxide being present in the final crystalline product when the melting point was being tested. Propose Mechanism of Reaction