October 20, 2003
OCN- 1202
Bromination of Stilbene
Abstract:
Trans-stilbene and elemental bromine reacts to form a white crystalline solid, 1,2-dibromo-1,2-diphenylethane. The crystalline solid is collected by vacuum filtration and through melting point analysis, the product is determined as the meso stereo isomer.
Techniques Used:
Electronic Analytical Balance
Melting Point Analysis
(no new techniques)
Procedure:
Trans-stilbene (0.8094g) is dissolved with approximately 6 mL of dichloromethane in a 25mL Erlenmeyer flask. Approximately 0.7mL of Br2 solution is placed into the flask and the contents become an orange-brown bromine color. The experimenter then swirled the flask continuously for 3 minutes and the orange-brown color began to fade. As the color faded, white crystalline solid precipitated. Another ~0.7mL of Br2 solution is added to the flask and the contents in the flask became orange/brown. The flask is swirled for another 3 minutes and the orange-brown color faded once again and more white crystalline crystals precipitated. For the third time, ~0.7mL of Br2 solution is added, the contents in the flask turned orange-brown. The flask is swirled once again for 3 minutes and the color faded and more crystals precipitated. Then, in ~0.1mL increments, an additional 0.3mL of Br2 solution is added and regardless of how long the flask was swirled, the bromine color persisted. Then, 2 drops of cyclohexene is added to the flask and the bromine color disappeared and became clear. The flask, after the addition of cyclohexene, became hot (exothermic) and was cooled in an ice-water bath. The white [had a tinge of yellow-brown color] crystalline solid is then isolated by vacuum filtration. The crystals were washed with 3 mL of cold [cooled in ice bath] cyclohexene. The crystals are then air dried for 2 days and a melting point analysis is conducted. The product isolated was white crystals (1.1136g, 74% yield) and gave a melting point range of 241-242 degrees Celsius.
OCN- 1202
Bromination of Stilbene
Abstract:
Trans-stilbene and elemental bromine reacts to form a white crystalline solid, 1,2-dibromo-1,2-diphenylethane. The crystalline solid is collected by vacuum filtration and through melting point analysis, the product is determined as the meso stereo isomer.
Techniques Used:
Electronic Analytical Balance
Melting Point Analysis
(no new techniques)
Procedure:
Trans-stilbene (0.8094g) is dissolved with approximately 6 mL of dichloromethane in a 25mL Erlenmeyer flask. Approximately 0.7mL of Br2 solution is placed into the flask and the contents become an orange-brown bromine color. The experimenter then swirled the flask continuously for 3 minutes and the orange-brown color began to fade. As the color faded, white crystalline solid precipitated. Another ~0.7mL of Br2 solution is added to the flask and the contents in the flask became orange/brown. The flask is swirled for another 3 minutes and the orange-brown color faded once again and more white crystalline crystals precipitated. For the third time, ~0.7mL of Br2 solution is added, the contents in the flask turned orange-brown. The flask is swirled once again for 3 minutes and the color faded and more crystals precipitated. Then, in ~0.1mL increments, an additional 0.3mL of Br2 solution is added and regardless of how long the flask was swirled, the bromine color persisted. Then, 2 drops of cyclohexene is added to the flask and the bromine color disappeared and became clear. The flask, after the addition of cyclohexene, became hot (exothermic) and was cooled in an ice-water bath. The white [had a tinge of yellow-brown color] crystalline solid is then isolated by vacuum filtration. The crystals were washed with 3 mL of cold [cooled in ice bath] cyclohexene. The crystals are then air dried for 2 days and a melting point analysis is conducted. The product isolated was white crystals (1.1136g, 74% yield) and gave a melting point range of 241-242 degrees Celsius.
