Org Prep Daily

September 7, 2006

BocOOBoc

Filed under: procedures — milkshake @ 12:18 am

newbocooboc.gif

Di-tert-Bu-peroxydicarbonate (di-Boc peroxide)

KOH 85% pellets 7.26g (110mmol) was dissolved in water 10mL. The solution was cooled on ice bath to 5C, THF 10mL and 50% hydrogen peroxide 3.4mL (55mmol) was added and the mixture was cooled back to 5C (internal thermometer). With vigorous stirring a solution of Boc anhydride 21.83g (100mmol) in THF 10mL was added and the mixture was stirred vigorously at 10C for 1 hour. (Some potassium peroxide hydrate precipitated). Water 20mL and THF 10mL was added and the mixture was stirred at 10C for additional 8 hours.  The reaction mixture was diluted with ice-cold water 100mL , extracted with ether 100mL, separated, the organic phase was washed with ice-cold water 100mL. Aqueous phases were re-extracted with ether 100mL. The combined extracts were dried with magnesium sulfate and evaporated from a 10C bath. The residue solidified upon brief drying (30 min) on highvac. NMR analysis of the crude product indicated 94:6 product/start. material ratio.

The crude product was dissolved in pentane 60mL (at room temperature) and the solution was placed into freezer overnight (-20C, 14 hours). The supernatants were poured away, the obtained large crystals in the flask were quickly rinsed with pentane (pre-cooled to -20C) and then dried on highvac.

Y=9.084g of a white crystalline solid (77.5% th). 1H(d6-acetone, 400MHz): 1.542 s

The product is heat-sensitive and most likely explosive. It must be stored in freezer.

Peroxydicarbonate diesters are useful radical initiators, for temperature range 40-70C. Because of their poor stability, peroxidiesters are not commercialy available from lab chemical suppliers. The BocOOBoc is the smallest crystalline  peroxydicarbonate. It is useful as a clean source of t-butoxy radical under mild conditions.  

Leave a Comment »

No comments yet.

RSS feed for comments on this post. TrackBack URI

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Blog at WordPress.com.

%d bloggers like this: