Alkene Addition Bromination Essay

1031 WordsAug 12, 20125 Pages
Old Dominion University ORGANIC 214 Alkene Addition Submitted by: Alkene addition: Bromination of (E) Stilbene Introduction: In this lab we used the greener approach, which involves the addition of bromine across a double bond. When bromine reacts with E-stilbene (trans-1,2-diphenylethene), two new chiral carbons are created from the sp2 carbons, therefore 3 different dibrominated stereoisomers are possible: meso-(1R,2S), or the raceminc mixture-(1R,2R) or (1S,2S)-dibromo-1,2-diphenylethane (Gilbert, 2010). When the bromination ion intermediate proceeds through a stereospecific mechanism, then the meso dibromide is formed exclusively. The racemic dibromides are formed from the concerted syn addition if the mechanism proceeds…show more content…
When the product was completely dry two different melting points were recorded, averaged and then compared to the standards in order to identify the product. The theoretical yield and percent yield were also calculated. Results: Reagent | Amount | (E)Stilbene | 0.200g | Cold Acetic Acid | 4mL | Pyridinuim Tribromide | 0.394g | DI water | 4mL | Methanol | 3mL | Table 1: Amount of Reagents Used Reagent and Products | Standard MP | Product MP1 | Product MP2 | Avg. MP | (E) Stilbene | 122°C -125°C | n/a | n/a | n/a | Dibromostilbene Meso Favored | 241°C - 243°C | 242.2°C -246.4°C | 243.0°C-247.1°C | 242.6°C -246.7°C | Dibromostilbene Racemic Favored | 113°C -114°C | n/a | n/a | n/a | Table 2: Melting Point Percent Yield Calculation | 0.200 g (E)-stilbene / 180.25 g/mol (E)-stilbene = | 0.00111 mol (E)-stilbene | 0.00111 mol (E)-stilbene X 1 mol dibromostilbene / 1 mole (E)-stilbene = | 0.00111 mol dibromostilbene | 0.00111 mol dibromostilbene X 340.058 g/mol dibromostilbene = | 0.377 g dibromostilbene | (Actual yield 0.275 grams / Theoretical yield 0.377 grams)x100 = | 72.9% percent yeild | Table 3: Calculations Discussion and

More about Alkene Addition Bromination Essay

Open Document