Microscale Procedure Place 50 Mg Each Of Tetraphenylcyclopentadienone Prepared In Chapter 51 And Diphenylacetylene Wh 1 (81.51 KiB) Viewed 31 times
Microscale Procedure Place 50 Mg Each Of Tetraphenylcyclopentadienone Prepared In Chapter 51 And Diphenylacetylene Wh 2 (20.26 KiB) Viewed 31 times
Microscale Procedure Place 50 mg each of tetraphenylcyclopentadienone (prepared in Chapter 51) and diphenylacetylene (which can be prepared in Chapter 58) in a reaction tube, clamp it upright, and heat the mixture with the flame of a microburner. This is the only experiment in this text that requires a flame to conduct a microscale reaction. Use care to ensure that no flammable solvents are nearby. Soon after the reactants have melted with strong bubbling, the white product becomes visible. Let the diphenyl- acetylene reflux briefly on the walls of the tube; then remove some of this excess diphenylacetylene by inserting a Pasteur pipette into the vapors above the solid and drawing the hot vapors into the pipette. Repeat this operation until it is possi- ble, through strong heating with the flame, to melt the mixture completely. Then let the melt cool and solidify. Add 0.25 mL of diphenyl ether (bp 259°C), heat the mix- ture carefully to dissolve the solid, then let the product crystallize slowly. Extin- guish the flame and, when the tube is cold, add 0.5 mL of toluene to dilute the mixture. Collect the product using the Pasteur pipette method or by vacuum filtra- tion on a Hirsch funnel and wash it with toluene. The yield of colorless plates is about 60 mg. Using a Mel-Temp apparatus, equipped with a 500°C thermometer, determine the melting point. To avoid oxidation, seal the sample in an evacuated capillary tube. The product should melt at 465°C. Cleaning Up. Place all filtrates in the organic solvents waste container.
C,H, C,H, CH, O C,H, Tetraphenylcyclopentadienone MW 384.45, mp 219°C CH, III C,H, Diphenylacetylene MW 178.32, mp 61°C C,HS C₂H₂ CH₂ CH, .C,H, CH₁ |-co go Hexaphenylbenzene MW 534.66 mp 465°C Energy-minimized conformation
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