Synthesis of benzil Renan Gongora Spring 2017

Outline Tetracyclone Retrosynthesis Ylide Benzoin Reflux Alcohol Oxidation Acyloin Condensation Ylide Benzoin Reflux Recrystallization Analyze Crude Caclulate % yield Get into pairs Outline 2

X Tetracyclone Used to make Shvo’s Catalyst (top structure) Oxidative coupling of primary alcohols to esters Oxidation of alcohols to form ketones Aldehyde, ketone and imine hydroboration Recall how low your yield was for the isopentyl acetate lab, this method could increase yield You’re not making this but you could X Brian L. Conley, Megan K. Pennington-Boggio, Emine Boz, and Travis J. Williams "Discovery, Applications, and Catalytic Mechanisms of Shvo’s Catalyst" Chemical Reviews, 2010, volume 110, pp. 2294–2312. doi:10.1021/cr9003133

Retrosynthesis Imagine if you wanted to make this compound, how could I make it using simple/inexpensive materials? Ask yourself “a snapshot before it was this molecule, what was it?” How do I know how to make it? Analogy: Hedge Maze.  create a map and then go through the maze.

Synthesis: The next two weeks (separate lab reports) HNO3 H2O/EtOH 1:3 v/v This week!!

Synthesis 1) Reflux in acid 2) Quench with Water 3) Purify HNO3 Oxidation Protip: You can determine if a carbon has been oxidized if there are less hydrogen atoms connected to it or if there are more oxygen atoms connected to it. benzoin benzil Which carbon was oxidized?

Only start refluxing after setup has been approved! Procedure Only start refluxing after setup has been approved! (2.5 g) (3.5 g) HNO3 (12 mL) set up reflux with gas trap 50 mL RBF 7

Only start refluxing after setup has been approved! Procedure Only start refluxing after setup has been approved! cool to r.t. ≈60 mins or until no more NO2 (g)

Procedure Vacuum Filter Washing with cold DI water twice (25 mL) SLOWLY quench with cool DI water and pour reaction mixture into water crude filter Stir unitl crystallization dispose filtrate in acid waste If no crystals form cool with an ice bath (40 mL)

Recrystallization Recall the purpose of your select solvent is At elevated temperatures: completely dissolve your product but At lower temperatures: your product should be i _ s _ l _ b _ e

Procedure EtOH under ice bath until crystals form just enough (≈0.5g/5mL of EtOH) sit at r.t. MILDLY heat until completely dissolved 100 mL RBF

Recrystallization Procedure Weigh filter paper before this step Vacuum Filter Washing with cold EtOH (5 m LX 2) EtOH (you calculate this volume)

Recall Reflux Prevents solvent loss Prevents buildup of pressure

Outline Tetracyclone Retrosynthesis Ylide Benzoin Reflux Alcohol Oxidation Acyloin Condensation Ylide Benzoin Reflux Recrystallization Analyze Crude Caclulate % yield Get into pairs Outline 14

Questions?