[robvba]

Suppose you are captured and placed in a medieval castle that is surrounded by a moat filled with reptiles of unusual size (ROUS). If you can make pentanoic acid, then you can pour it into the moat, kill the reptiles, and swim to safety (I'm presuming you can swim, if not, then it's time to learn). In your castle you have found a door that say's "Merlin's Room" and inside there is a well-equipped lab that has a vented hood with bottles of THF, H2SO4, HBr, NaOH, NaNH2, 1-butanol, ethanol, every metal, pig's ear, cow's tongue, eye of a newt, and a green laser pointer (I love those things). Of course you have access to heat, light, anything in the air, and water from the moat. Show how you would make pentanoic acid. You need to make it fast. There's no food or potable water in the castle. And your captors smashed your cell phone.

[macman104]

You need to provide some indication that you've given this problem some thought.

[robvba]

our product consists of five carbons. we have immediate access to a chain of four carbons and two carbons. synthesis would produce a chain of six carbons, or four carbons if we synthesize two ethanols. we need to remove one carbon. need some help here.
we could use animals parts to separate the fats (glycerol and fatty acid) but not sure how or if that would produce anything.

[azmanam]

What ways do you know to remove carbons?  That is, what reactions do you know that can break carbon-carbon bonds?

[robvba]

What ways do you know to remove carbons?  That is, what reactions do you know that can break carbon-carbon bonds?

I know the haloform reaction, but it doesnt look like we have any chlorine

[azmanam]

Good start.  You're right, though, I don't think we need the haloform to complete this synthesis.  Can you go back through the functional groups you've learned about to see if there are any other reactions to fragment molecules into pieces?  You've shown that methyl ketones can be used to break carbon-carbon bonds.  What else?

[James Newby]

pour HBr into the moat, wait for the reptiles to die, neutralise with the NaOH then swim to safety

[robvba]

Good start.  You're right, though, I don't think we need the haloform to complete this synthesis.  Can you go back through the functional groups you've learned about to see if there are any other reactions to fragment molecules into pieces?  You've shown that methyl ketones can be used to break carbon-carbon bonds.  What else?

ozonolysis and carbon dioxide is not at our disposal as far as i can tell. i dont recall any other.

[azmanam]

If you can't use ozonolysis (which is what I would have suggested), then you should at least be able to dihydroxylate/cleave.  I think the question is a cute way of saying 'using butanol, ethanol, and any inorganic reagents...'

[robvba]

If you can't use ozonolysis (which is what I would have suggested), then you should at least be able to dihydroxylate/cleave.  I think the question is a cute way of saying 'using butanol, ethanol, and any inorganic reagents...'

unless we can use the laser pointer with oxygen in the air to make ozone. i'm just not sure how we can isolate the ozone.

dihydroxylate? not familiar with it. how would that work?

[robvba]

If you can't use ozonolysis (which is what I would have suggested), then you should at least be able to dihydroxylate/cleave.  I think the question is a cute way of saying 'using butanol, ethanol, and any inorganic reagents...'

unless we can use the laser pointer with oxygen in the air to make ozone. i'm just not sure how we can isolate the ozone.

dihydroxylate? not familiar with it. how would that work?

can someone please help

[azmanam]

start here:

http://www.cem.msu.edu/~reusch/VirtTxtJml/addene2.htm#add4b

[robvba]

start here:

http://www.cem.msu.edu/~reusch/VirtTxtJml/addene2.htm#add4b

if we're talking about KMnO4 or O3, what i dont know is how to isolate these reagents for our reaction. If you read the above, we do not have these reagens readitly available. we do have the metals, but not permanganate or ozone.

[azmanam]

in my opinion, 'every metal' means that you can use any inorganic reagent (like OsO₄).  You should check with your prof, though. 

If you really don't have inorganic metal complexes (like vOsO₄), then I don't see a way to do it with the small amt of reagents you have.  you can get to a Grignard, which I think you'll need, but I don't see how you do an oxidation (which you'll need at some point) with just those reagents.

[robvba]

in my opinion, 'every metal' means that you can use any inorganic reagent (like OsO₄).  You should check with your prof, though. 

If you really don't have inorganic metal complexes (like vOsO₄), then I don't see a way to do it with the small amt of reagents you have.  you can get to a Grignard, which I think you'll need, but I don't see how you do an oxidation (which you'll need at some point) with just those reagents.

i'll have to ask about that. however, is it not possible to react laser pointer with oxygen to get ozone?