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Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: Darkstar on September 08, 2004, 11:02:58 PM

Title: cyclopentene to 1,5-pentadiol
Post by: Darkstar on September 08, 2004, 11:02:58 PM

Can you oxidize cyclopentene into 1,5-pentadiol in one stage?

Title: Re:cyclopentene to 1,5-pentadiol
Post by: movies on September 09, 2004, 12:05:37 AM

Ozonolysis with a reductive work-up (NaBH₄) should do the trick.

Title: Re:cyclopentene to 1,5-pentadiol
Post by: Darkstar on September 09, 2004, 07:25:26 AM

Yes, apparently this is what they mean. A one stage process that consists of two parts :) I just thought maybe there's some sort of magic reagent I've never heard about, some selenium astatide or something...

Title: Re:cyclopentene to 1,5-pentadiol
Post by: movies on September 09, 2004, 12:14:51 PM

I don't know much selenium chemistry, so there might be something.

Ozonolysis is always a two stage process.  I think that the NaBH4 step is essentially just tossing in some NaBH4 when the ozone addition is done, so it's virtually a one step conversion.  The ozonolysis to give the aldehydes would use a Me₂S workup, so it's not like you would avoid a step otherwise.

Title: Re:cyclopentene to 1,5-pentadiol
Post by: huoshiyong on September 09, 2004, 10:03:44 PM

with H2O2

Title: Re:cyclopentene to 1,5-pentadiol
Post by: Darkstar on September 12, 2004, 10:36:40 PM

H2O2 will not split up the cyclopentene molecule at the C=C bond (?). It will only lead to epoxidation.

Title: Re:cyclopentene to 1,5-pentadiol
Post by: Donaldson Tan on September 13, 2004, 01:51:02 AM

How about Jone's Reagent? Or Using Cold Alkali KMnO₄ ??

Title: Re:cyclopentene to 1,5-pentadiol
Post by: movies on September 13, 2004, 11:49:51 AM

I don't think that Jones reagent will oxidize double bonds.  KMnO₄ can dihydroxylate (sometimes even cleave to the aldehydes, but then will oxidize to the acid), but then you still have to do another step or two to open the ring and get the alcohols.

BTW, H₂O₂ is a poor epoxidizing agent for olefins.  It does, however, work well for epoxidizing enones.  For olefins, electrophilic epoxidizing agents are better (e.g. m-chloroperbenzoic acid).