Ochem question

[jmcfa002]

Advertisement - Members don't see this ad

I'm trying to figure out a synthesis for lab...
I need to make o-hydroxytoluene(http://chemicalland21.com/industrialchem/organic/ortho-CRESOL.htm) become salicylic acid(http://en.wikipedia.org/wiki/Salicylic_acid)

basically I either need to turn a methyl into a carboxilic acid

or change a methyl group to an alcohol and change an alcohol to a carboxilic acid.

anyone have any ideas?

I know I could used CN- and H+ to change the OH to a carboxilic acid, but I don't know what I can do to the methyl

 

[ester]

You can oxidize a methyl group on an aromatic ring system using potassium permanganate or dichromate as seen in an example at http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch11/ch11-9-2.html.

 

[jmcfa002]

THanks! I looked for a long time last night and couldn't find anything

 

[ester]

It's okay! I used to sit around and think up multiple step synthesis for "fun" when I took ochem (hahaha, not for fun, just to keep my mind sharp). I guess some of it has stuck even though I'm out of ochem.

 

[Hiper]

You can oxidize a methyl group on an aromatic ring system using potassium permanganate or dichromate as seen in an example at http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch11/ch11-9-2.html.

That won't work, you'll also oxidize the alcohol group to produce o-benzenedicarboxylic acid

You need to use an alcohol protecting group first.


Use silyl ethers to act as protecting groups and then use KMnO4 in an alkaline environment (don't use KMnO4 over acidic enviroment like the link showed) to oxidize the methyl groups. Addition of dilute sulfuric acid will produce carboxylic acid from the carboxylate AND remove the silyl protecting groups to reveal salicylic acid.

 

[deleted205891]

Wow I was thinking KMnO4 at first, but yeah, that wont work, thatll oxidize everything. I agree with the protecting group.

 

[ester]

Yep your right. I didn't look at the compounds much and just answered his question about what he could do with R groups. Silly me.