Jun 8, 2009
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I was looking over the destroyer roadmaps. I have the 2008 destroyer so hopefully the roadmaps are same. Anyways in Roadmap #6 they use P2O5 with heat. I do not understand that step and its mechanism. What is P2O5 with heat suppose to do?


Also they use CrO3, Pyr, Ch2Cl2. Which I think is Jones Reagent and I am pretty sure it is suppose to work like KMnO4 and strong oxidizing agent taking all the way to COOH. But the step they used it in says it acts like PCC. Ummmmm why??? I referred to MCAT kaplan book, and another book and both say Jones Reagent is like KMnO4. What am I missing here? Is it because CrO3 here is with Pyr or something? Someone please explain.

Thank You for your help in advance:)
 
Last edited:
Jul 23, 2009
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Pre-Dental
same here. haven't seen P2O5 rxn in ochem book, so i just wikipedia-ed it.. the link is here http://en.wikipedia.org/wiki/P2O5

it just says that this is used in organic synthesis for dehydration, most importantly conversion of AMIDES into NITRILES which you can see in the road map.

for CrO3, it is jone's reagent, but what happened here i think is.. the indication of Pyr???? i'm not sure if that is an abbreviation for pyridinium? (pyridinium chlorochromate = PCC).. usually PCC is used with methylene chloride (CH2Cl2) as a solvent and here it is used in that solvent with 40C.. Jone's reagent is defined as a solution of chromium trioxide (CrO3) in a concentrated sulfuric acid (H2SO4) -- and the solvent used in here is acetone.. so i guess it depends on the solvent that you are using.
 
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Jun 8, 2009
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same here. haven't seen P2O5 rxn in ochem book, so i just wikipedia-ed it.. the link is here http://en.wikipedia.org/wiki/P2O5

it just says that this is used in organic synthesis for dehydration, most importantly conversion of AMIDES into NITRILES which you can see in the road map.

for CrO3, it is jone's reagent, but what happened here i think is.. the indication of Pyr???? i'm not sure if that is an abbreviation for pyridinium? (pyridinium chlorochromate = PCC).. usually PCC is used with methylene chloride (CH2Cl2) as a solvent and here it is used in that solvent with 40C.. Jone's reagent is defined as a solution of chromium trioxide (CrO3) in a concentrated sulfuric acid (H2SO4) -- and the solvent used in here is acetone.. so i guess it depends on the solvent that you are using.
oh I c. thanks! :) I am like 2 weeks away from my test and the last thing i wanted to find were weird reagents i never knew of. So I started freaking out. But Your explanation helped.
 

pauly11235

10+ Year Member
Jul 25, 2008
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Dental Student
P2O5 just removes 2 H's and an O from the molecule. (basically removes a water molecule) To help you remember it,( this may be very silly) but when you see P like in P2O5, means you have to pee and lose water. :)
 
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OP
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Jun 8, 2009
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P2O5 just removes 2 H's and an O from the molecule. (basically removes a water molecule) To help you remember it,( this may be very silly) but when you see P like in P2O5, means you have to pee and lose water. :)
lol, thats a great way to remember. Thanks a lot :thumbup: :D
 
Jun 30, 2011
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New York
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Pre-Podiatry
That's how I learned it too.. considering I take a course with the Dr. Romano the author of the Destroyer... Just remember that it works for all the P's...For example if you have P4O10...you still would lose a water.. Good luck!