Chemical Forums
Chemistry Forums for Students => Organic Chemistry Forum => Topic started by: al on April 18, 2005, 04:10:46 PM
-
Hi everyone
how would i convert benzene to Benzene with a CH2OCH3 attached to it?
-
I think you might have an easier time if you tried to add the methoxy group (H3C-O-) to toluene since toluene already has the methyl group in place there. I'm just not sure on how this could be done.
-
Actually, now correct me if I'm wrong, couldn't you use a simple esterification reaction by mixing toluic acid (Toluene with a -O-OH group on the non-ringed methyl portion), concentrated sulfuric acid, and methanol? Wouldn't this result in the formation of the toluene ester requested and water?
-
Jdurg: that would make the ester, but the ether is desired. I can't think of a good way to reduce an ester to an ether.
I think that there are a lot of ways to achieve this transformation though. One of them would use benzoic acid (toluoic acid). Do you know an easy way to make benzoic acid from benzene?
-
making benzoic acid from benzene:
I think it would be easily done if you first converted benzene to toulene then with the addition of KMnO4, H20 that would give you the benzoic acid
-
You may be best off running a Friedel-Crafts. Take benzene and react it with chloromethyl methyl ether and AlCl3.
-
I have a couple steps if you want....
1. Friedel Crafts Alkylation (or you can start with Toluene)
Benzene + CH3Cl -----AlCl3, 0*C----> Toluene
2. Free-Radical Halogenation of AlyklBenzenes
Toluene + Br2 ------ 80*C, chloroform-----> Benzyl Bromide
3. Nucleophilic Substitution in Bezylic Halides
Benzyl Bromide + NaOCH3 -----> your desired product ;)
-
I think that the conversion of benzene to toluene by F-C is really difficult because methyl cation is really unstable. It might work, however.
The method that TCUrob suggested is definitely the most direct.
The route I was thinking of to benzoic acid was to make phenyl lithium (or phenyl Grignard) from benzene and then quench it with CO2. That would give the acid directly.
You could reduce the acid to the alcohol then with LiAlH4 and then make the ether using the Williamson ether synthesis (NaH + CH3I). Longer, but does get to the product.
A more direct way would be to make phenyl lithium (benzene + n-BuLi) and quench with formaldehyde to give benzyl alcohol directly. Sometimes you can even alkylate carbanions with things like chloromethyl methyl ether (MOM-Cl), which might give the product directly. These reactions are usually pretty messy though.
-
I think that the conversion of benzene to toluene by F-C is really difficult because methyl cation is really unstable. It might work, however.
I believe with methyl or primary, it reacts direct with no cation
BUT...you are right, I forgot that it is hard. It will work, but it's not very efficient
-
I have a good method, i think
first react benzene with CO+HCl in presence of AlCl3 & Cu2Cl2. this is the Gatterman Koch rxn. It will give Benzaldehyde. reduce with LAH to give benzyl alcohol. React with PBr5, to give benzyl bromide.Now react with sodium methoxide.
VOILA!
-
Actually, now correct me if I'm wrong, couldn't you use a simple esterification reaction by mixing toluic acid (Toluene with a -O-OH group on the non-ringed methyl portion), concentrated sulfuric acid, and methanol? Wouldn't this result in the formation of the toluene ester requested and water?
I believe you mean condensation, esterification is between an alcohol and a carboxylic acid :)
it might work, but isn't condensation of two alcohols limited to similar alcohols? please correct me if im wrong.
-
Benzene, CO, PBr5, MOM-Cl they are all dangerous reagents.
Use Toluene + NBS --> Benzyl-Bromide
Then use sodium methoxide as above.
By the way Gatterman Koch reaction and the F-C alkylation posted by Ad Majorem Dei Gloriam require a high pressure reactor, very dangerous.
There are always dozens of ways to obtain a product, but which one is the safest ?