Sciencemadness Discussion Board

nitration of xylene using HNO3/DCM mixture

mackolol - 28-2-2018 at 08:35

Hi, I want to make 2,6 xylidine and i dont have better idea than to make it from mixed xylenes. However separation of isomers is huge pain in the ass. So im wondering if toluene nitrated by this mixture forms only ortho isomer then if it will work with xylene, what isomers will be created and if this will help in any point.

sykronizer - 6-3-2018 at 16:54

Look up Urbanski there is plenty of literature concerning different nitration mixtures and nitration of Xylene...typically around 80 percent sulfuric and 20 percent nitric is a mixture that will get you to trinitro xylene in one step...but you MUST read the literature regarding the temperature control because it can cook off and that's the last thing you want..

[Edited on 7-3-2018 by sykronizer]

Boffis - 8-3-2018 at 06:03

@mackolol, I have been reading up on this subject. From what I can find in papers by Strazzolini et al. (bull.chem.soc.japan Strazzolini et al 1995 p1155-1158 and JOrgChem Strazzolini et al 1998; v63; p952-958) the use of HNO3 in DCM in the nitration of toluene only enhance the yield of o isomer when the methyl group is substituted and that you get pretty much the same isomer ration as with mixed acid for toluene. My understanding is that you need an oxygen bearing group on the methyl group to coordinate with the nitric acid prior to nitration. So on this basis I would be surprises if you got any difference in isomer ratios between HNO3-DCM and mixed acids with m-xylene.

According to Kobe and Brennacke (Industrial and Engineering Chemistry, 1954, vol 45, p728-732) the nitration of m-xylene under mild conditions yields only about 15% 2-nitro-m-xylene and 85% nitro-m-xylene. It does not sound likely that the use of anhydrous nitric acid in DCM will significantly increase this.

I would check out Reaxys if you know someone with access or have access to the ref section of MS. There may be indirect routes say by low temperature sulphonation of m-xylene to m-xylene-4-sulphonic acid, low temperature nitration of this to 2-nitro-m-xylene-4-sulphonic acid followed by hydrolysis to the 2-nitro derivative. I don't know if this scheme would work but I'll bet that the old boys had worked out a route back in the hay-days of the dye industry.

Lidocaine may be a possible source since it occasionally pops up on eBay Europe; unless of course that's what you are trying to make.

mackolol - 10-3-2018 at 10:15

Yup i'm trying to make lidocaine and it would be great if it was pure enough to test it safely on myself. (I have access to lidocaine but want to make it on my own). And as You know Boffis i've tried separating xylene isomers by sulfonation but I didnt make it. It's so hard to say if it is meta isomer because all of them participate in this reaction.

Keras - 26-7-2019 at 09:07

I am sorta resurrecting this thread, because I find the idea (i.e. to synthesise lidocaine) interesting.

Did you have any success in nitrating your xylene mixture?

I would probably first try to isolate m-xylene from its other isomers. Apparently, m-xylene forms an azeotrope with water, and the other isomers don’t. I'm not sure about that, though.

Herr Haber - 29-7-2019 at 03:49

Urbanski tome I mentions a few methods of separation before or after nitration.
It also suggests the best source for xylene depending on what isomer you are looking for.

Always a great read :)