Question

1 Calulate the percent yeild. Show work. explain the percent yield

2)Which stereoisomer of Dibromosuccinic acid(racemic melting point =170° C meso melting point = 290°C ) did you obtain? Draw it and showing mechanism to justify its transformation. PLEASE EXPLAIN

3) Explain the chemistry of the experiment.

LAB /4-1-27 Preparation of Dibromosuccinic Acid Introduction: In this experiment, you will add bromine across the double bond of f mar determine the stereochemistry of your product via melting point. ou will then HO2C cO2H 15-19 fumaric acid 1.2 Safety Hazards: Bromine is a corrosive gas. It can burn your skin and respiratory tract. It should be kept covered at all times and dispensed only under the hood while wearing gloves. , s← setup bata Experimental Procedure: Weigh out 0.2 g of fumaric acid and place it in a 25 mL. Erlenmeyer flask. odded became ora Cautiously (under a hood and while wearing gloves) add 2.5 mL of bromine stock solution. Heat the resulting solution in a boiling water bath under the hood for 12-15 minutes. If the solution becomes colorless at any point during the heating period, add a few drops of bromine stock solution to maintain a pale yellow to orange color. set up vacum The precipitate that forms during the heating period is your product. After the heating peri flask in ice and collect the product by vacuum filtration. Rinse the product with ice cold water. od, cool your Allow the product to dry for I week. Then determine its yield and melting point. muda produ be wa mass of the product is.09g melting point of the product is 250-251 °C

Answer 1

Bromination of fumaric acid HO он HO2Cl CO2H meso-Dibromo succinic acid Fumaric acid Mol. Wt.: 116.07 0.2g0.00172 mol Mol. Wt.: 275.88 Lit mp 290° 0.00172 mol -0.475 g According to the above equation 1 mole of fumaric acid produces 1 mole of meso-Dibromo succinic acid So, 0.2 g of fumaric acid produces 1 x 0.2-0.2 mole= 0.475 g of meso-Dibromo succinic acid So, theoritical yield 0.475 g We know, actual yield- 0.091g Therefore, percent yield-(Actual yield /theoritical yield) x 100 - (0.09 x 100)/0.475 18.947 % Lit mp of meso-Dibromo succinic acid is 290° and lit mp ofracemic-Dibromo succinic acid is 170° Observed mp 250-251° which indicates that bromination of fumaric produces meso-Dibromo succinic acid Which is supported by the reaction mechanism as shown below Mechanism: Br-Br HO JIUJIH он HO2C CO2H Br Br CO2H Fumaric acid meso-Dibromo succinic acid