Sciencemadness Discussion Board

What would the procedure for Benzidine to aniline look like?

njl - 26-11-2019 at 13:33

Is is silly to assume a one step conversion in an acidic solution is possible?

Edit: On a tangentially related note, is there any immediate problem with substituting propylene glycol with regular glycerin in the isolation of terephthalic acid from PET plastic?

http://www.sciencemadness.org/member_publications/terephthal...

[Edited on 26-11-2019 by njl]

DavidJR - 26-11-2019 at 14:14

I doubt there is an easy way to break that carbon-carbon bond.

Also, be careful with benzidine, it is a very potent carcinogen.

Boffis - 26-11-2019 at 15:04

Glycerin is not stable enough at high temperatures to replace ethylene or propylene glycol in the depolymerisation of PET.

If you can get benzidine surely you can get aniline! Benzidine is now highly controlled in most countries due to its known toxicity.

njl - 26-11-2019 at 15:24

Thanks. I wasn't planning on using it in any particular reaction, just wondering if there was a known mechanism for the cleavage of that single bond between two rings. I've noticed that many similar compounds with two linked aromatic rings seem to be awfully toxic. Is there a reason Benzidine derivatives (and those of similar structures) are so nasty?

draculic acid69 - 26-11-2019 at 22:11

Quote: Originally posted by njl  
Is is silly to assume a one step conversion in an acidic solution is possible?

Edit: On a tangentially related note, is there any immediate problem with substituting propylene glycol with regular glycerin in the isolation of terephthalic acid from PET plastic?

http://www.sciencemadness.org/member_publications/terephthal...

[Edited on 26-11-2019 by njl]


Extractions and ire or explosions and fire has a video of decomposition of pet in glycol to get the terepthalic acid. If u watch his videos you'll get some good info.i think if I was doing it is try it in just water in a pressure cooker.the idea of adding glycol just to
have to deal with it later seems like a hassle that might not be necessary.watch the videos.
https://m.youtube.com/watch?v=JuvczYeM3kk
https://m.youtube.com/watch?v=uRTrjaAb4NA
https://m.youtube.com/watch?v=Zh0RK0an8f4

draculic acid69 - 26-11-2019 at 22:14

Also glycerine is more expensive than glycols.

Pumukli - 27-11-2019 at 00:01

One will get glycol anyway bacause the hydrolysis of PET produces ethylene glycol and terephthalic acid in equimolar proportions.

As for the toxicity of benzidine: my understanding is that the problem lies in the two p,p'-positioned amino groups and the distance between these groups. These groups can criss-cross link the DNA strands because they are similarly basic as the nucleotides (adenine, thymine, guanine, cytosine) in the normal DNA. The structurally damaged DNA causes cancers sooner or later.

Metacelsus - 27-11-2019 at 05:18

In particular, the benzidine is metabolically acetylated and oxidized to an N-hydroxy compound, which then forms a nitrenium ion. This can react with DNA. See: https://www.ncbi.nlm.nih.gov/pubmed/455295

Other aromatic amines can react similarly.