Synthesis of Diphenylacetylene

Anthony Felix 10/27/11 Che12ALR Synthesis of Diphenylacetylene Observation of Results 1,2-dibromo-1,2-diphenylethane 0. 204g Diphenylacetylene 0. 087g Theoretical give back 0. 107g Percent yield 81. 3% Melting point range of diphenylacetylene 57- 60C ordinary melt point 58. 5C Average lit melting point 60. 0C Percent illusion of melting point 2. 5% Calculations Theoretical yield Limiting reagent (LR) x M. W. (LR) x breakwater 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 = Average m elting point Average melting point (59+ 61)/2 = 60C Average writings melting point Percent error imperative value (Abs) (actual yield theoretical yield)/ theoretical x 100% = percent error Abs. 58. 5 60)/ 60 x 100 = 2. 5% Scheme of the response (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 overdue 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 ordinary 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 6 0C, so the percent error is 2. 5%. Some error that could have occurred was that some of the product was left in the round bottom 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