Sciencemadness Discussion Board

Removal of alkyl ramifications

rvitorper - 5-10-2011 at 08:49

Hello,
Is there any practical way of removing alkyl ramifications from aromatic compounds such as converting xylene into benzene?

Thanks for your attention

Steve_hi - 5-10-2011 at 09:12

Dont know if this helps but here you go anyways
http://www.sciencemadness.org/talk/viewthread.php?tid=325

ThatchemistKid - 5-10-2011 at 10:10

Well, I think probably the easiest way in the situation with xylene or toluene would be the oxidation of the methyl groups with permanganate or chromic acid. Oxidation all the way to the carboxylic acid dervative of the aromatic compound, followed by making of the sodium salt of the carboxylic acid by NaOH neutralization. Isolating the formed salt and through mixing with a mortar and pestle of the salt with solid NaOH or Ca(OH)2.(personally ive always used NaOH, but I have seen lots of examples of the decarboxylation reaction done with Ca(OH)2 .) the mixture would then be heated via a heating mantle till an orange liquid starts to distill over. That orange liquid is benzene + other impurities, redistillation of that orange liquid and collection of the fraction boiling at 80 degrees C gives you clean benzene. Your best bet though is to buy some benzoic acid or sodium benzoate from EBAY or some other source, it is inexpensive and would help you to get around the oxidation mess, because trust me oxidation and purification of the carboxylic acid from the xylene or toluene with chromic acid or permanganate is messy, produces tons of waste... for the Chromic acid oxidation the oxidant is highly toxic.
and extraction of the product in any good yeild from the mess can easily turn into a complicated discusting nightmare.. or atleast that was my experience.

Nicodem - 5-10-2011 at 10:13

If you UTFSE you can find articles like this:
https://www.sciencemadness.org/whisper/viewthread.php?tid=32...

Rvitorper, please open referenceless and/or beginner threads only in the Beginners section where I'm moving this.