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Unformatted text preview: Experiment 3: Horner-Wadsworth-Emmons addition of benzalde- hyde, yielding stilbene Theory & Background: Olefns are an important class oF compounds in organic chemistry. They may be synthesized by several means, oF which the Horner-Wadsworth- Emmons reaction is among the most convenient and mild. This is considered to be a modifcation oF the original Wittig reaction, For which George Wittig received the chemis- try Nobel prize in 1979. In this reaction, phase transFer catalysis occurs at the interFace oF the two liquids. The reagents themselves reside in diFFerent immiscible solvents. The phosphonate becomes deprotonated and undergoes reaction with benzaldehyde. The reaction should be monitored by a three lane TLC. H O + P OEt O OEt NaOH / H 2 O aliquat 336 hexane + main Please regenerate this table in your notebook flling in any oF the blanks Reagents Values benzaldehyde diethyl benzylphosphonate aliquat 336 sodium hydroxide caustic 40 wt% =10M Product stilbene Formula C 7 H 6 O C 11 H 17 O 3 P C 25 H 54 ClN HNaO C 14 H 12 equiv 1.0 1.1 0.2 15 MW density volume mass mmol. melting point boiling point (N) Glassware Set-up: Procedure: Add benzaldehyde (100 mg, 1.0 equiv) to a 5.0 mL vial equipped with a spin vane. Then add Aliquat 336 (0.2 equiv), diethyl benzylphosphonate (1.1 equiv), hexanes (1.5 mL), and aqueous NaOH (15 equiv). Attach a water condenser to the vial, place on a stir plate with an aluminum block and stir as vig- orously as possible. Heat to reux until the reaction is complete by TLC analysis (~1 hour). (Be sure to draw pictures oF your developed plates into your notebook) 16 Techniques Phase Transfer Catalysis...
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- Winter '07
- Organic chemistry