CrO3 oxidizing agent

[molar3]

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WHAT the heck does cro3 do??? in KAPLAN it says cr03 is jones' reagent and it oxidizes a PRIMARY ALCOHOL straight to a CARBOXYLIC ACID.
BUT, in DAT destroyer, in one of the road maps, it says that Cr03 does the same thing as PCC meaning it oxidizes a primary alcohol only to the intermediate aldehyde.
Now im just confused as hell. which one is right?! IM SO CONFUSED, and i cant just let it go !! i need to know!! please help!!!!! thanks in advance!!!

 

[Spartan812]

Well from what I've searched, Jones' reagent does convert primary alcohols to carboxylic acids. Are you sure in the DAT Destroyer it's not adding pyridine and HCl to the CrO3? Because if it is, then CrO3 + pyridine + HCl = PCC. Remember, Jones' reagent = CrO3, acid and acetone

 

[gigawatt]

Well from what I've searched, Jones' reagent does convert primary alcohols to carboxylic acids. Are you sure in the DAT Destroyer it's not adding pyridine and HCl to the CrO3? Because if it is, then CrO3 + pyridine + HCl = PCC. Remember, Jones' reagent = CrO3, acid and acetone

Good to know! I wouldn't have recognized PCC if were to show up on the DAT as the combination of those reagents...might come in handy.

 

[adianadiadi]

Initially, Jones reagent oxidizes the primary alcohols to aldehydes, which are again oxidized by giving finally the carboxylic acids in water.

You will get the nice explanation at http://www.adichemistry.com/organic/organicreagents/jones/jones-reagent-reaction-1.html

Adi

 

[Ibraiz]

So Jones reagent is a mild oxidizing agent unless it is used with water as an solvent?

If it is not used with water as a solvent, would it act similar to PCC?
If it is used with water as a solvent, would it act similar to KMNO4 as a strong oxidizing agent?

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http://www.adichemadi.com/organic/or...sreagent1.html

 

[Baylor2011]

It's not Jones unless it is in aqueous H2SO4 (H2SO4/H2O) - if it's in CH2Cl2 (somewhat inert), it's much less reactive

They also added pyridine, so I assume they're wanting you to think more along the lines of PCC

 

[Ibraiz]

Thanks Baylor2011.

Would it be safe to assume:

1) Cr03 + H2SO4 = Jones (if H2S04 is missing then its not Jones reagent)
2) If Jones reagent plus Pyr = mild oxidizing agent - act same as PCC
3) If Jones reagent plus H20 = strong oxidizing agent

 

[Baylor2011]

That's what I'd do! Because w/ H2SO4, there's automatically H2O, but yah if they just put H2O, thats what I'd assume, but I doubt you'll see that

 

[Ibraiz]

If there was no H20 present and all we had was Cr03/H2S04, does this act like PCC or strong oxidizing agent?

If it acts like a strong oxidizing agent because H2S04 is aqueous?

 

[adianadiadi]

If there was no H20 present and all we had was Cr03/H2S04, does this act like PCC or strong oxidizing agent?

If it acts like a strong oxidizing agent because H2S04 is aqueous?

Yes! You are right. We use dilute sulfuric acid. Means there is water. Water is required as a base. If this base is pyridine, then it is possible to stop the reaction at aldehyde stage.