Sciencemadness Discussion Board - Zinin Reaction (Aniline synthesis) Experimental test Report

Zinin Reaction (Aniline synthesis) Experimental test Report

gboneu - 9-9-2015 at 17:47

Hello everyone-
so i was investigating an alternative method of synthesis of aniline because Tin (Sn) Is extremely expensive in Argentina, and recycling is possible, but time consuming, so i decided to go try another reactions. I tried with iron, but after 3 hours of reaction with the hydrochloric acid i have (round 21%) i got nothing, not worth steam distilling.
So i found the zinin reaction, which mentioned chemicals i have in the lab, so i decided to go en investigate to make it, And after investigating a little bit in google i found poor information, But sufficient to go and try it.
The reaction is the following:

4C6H5NO2 + 6Na2S + 7H2O = 4C6H5NH2 + 3Na2S2O3 + 7OH(-)

But it was obvious that something was missing so after searching i found that Ethanol or Methanol were good solvents, Know then i found the hydrolysis of the sulfide ion (Weak acid that hydrolyzes to make basic solutions) is necessary for the reaction, With all this and knowing that a little excess of sulfide reagent was necessary because of side reactions.
I did the stoichiometry and used these amounts of reagents.

Nitrobenzene = 10 ml
Sodium Sulfide (Nonahydrate) = 16g
Ethanol (96%) = 50 ml
Water = 50ml
The reaction was done in reflux or something like 1 + 1/2 hours in a 150 ml erlenmeyer flask.
after that i transfer all in a 500ml flat bottom flask and set for simple distillation. First 70 ml of a clear yellow liquid was collected in the 250 erlenmeyer flask as you see in the images.
When a turbid distilled started to come over and i switch the collector to a beaker. And got everything up to 200 ml
I've noticed that the first portion had a Nitrobenzene odor.
But the liquid portion had a aniline smell. so i got exited and post this. The yield is not amazing but ir works i will try to do some more reactions, if you have ideas that you want me to try i will look at theme.
The Reagents i've used where very pure.
Nitrobenzene (99.9%)
Sodium Sulfide (60%)
Ethanol (96%) (I had a Ethanol densimeter and got the same result )
Distilled water.
After distillation was started, i tested the PH of the solution and related basic in phenolphthalein, I also test for the formation of Sulfur with acid and got Positive Result. So the reaction has to be working

Ok thanks for your attention, hope these is useful for somebody
NOTE (THE REAGENTS NAMES IN SPANISH BECAUSE I LIVE IN ARGENTINA...GREETING TO ALL

)

[Edited on 10-9-2015 by gboneu]

Pumukli - 10-9-2015 at 21:39

Hello gboneu,

Nice experiment!
I am surprised that iron produced such bad results though. Isn't it (iron) used in the industrial scale reductions of nitrobenzene?

I'm not familiar with the Zinin reaction but has faint memories of Na₂S (or NaHS) being used in cautious, selective reduction of dinitro compounds, yielding only one nitro group reduced to amine, the other nitro not being bothered. Maybe you could find an apropriate compound to try this with Na₂S.

Boffis - 11-9-2015 at 14:23

Would the sodium sulphide reduction of picric acid and 2,4-dinitrophenol to the corresponding 2-aminophenol constitute a Zinin reaction?

Pumukli - 11-9-2015 at 21:29

I think it would.
See: https://en.wikipedia.org/wiki/Zinin_reaction

gboneu - 12-9-2015 at 18:51

Quote: Originally posted by Boffis

Would the sodium sulphide reduction of picric acid and 2,4-dinitrophenol to the corresponding 2-aminophenol constitute a Zinin reaction?

Yeah it would be great

But the problem is that i have no nitro compound except nitrobenzene, And Aniline is something i want to have but never got the chance to do a good synthesis, And The reason why i didn't have good results with The Iron based reduction was i believe my poor quality of hydrochloric acid,

byko3y - 13-9-2015 at 05:57

Why the hell is there so few references to zinin reaction in the internet? As you've said, Fe/HCl reduction is a pain in the ass, a lot of people have problems performing it. While zinin reaction can also selectively reduce nitro groups and uses non-restricted chemicals (I'm talking about HCl).

Boffis - 13-9-2015 at 06:18

The problem seems to be that it is rarely referred to as the "Zinin reaction". There is actually a lot of information about specific uses of sulphide, polysulphide and hydrogen sulphide reductions of nitrocompounds; check out books on dye chemistry, org synth (eg m-nitroaniline) etc.

However, on the subject of iron reduction of nitrobenzene to aniline there is a lot of information available, some very detailed on this forums library.

zed - 13-9-2015 at 13:29

Simple Hydrogenation might be a nice alternative.

In fact, if you have pressure equipment, it presents a kind of interesting neo-industrial alternative.

If you can produce maybe five-ten atmospheres, and a little heat....Tungsten Carbide/H2 in an acid environment, is reputed to perform this reduction readily.

Tungsten Carbide avoids the expense of Pt type catalysts, AND the Carbide resists poisoning.

[Edited on 13-9-2015 by zed]

gboneu - 13-9-2015 at 16:04

I believe that the reason why the zinin reaction is no so detailed in the synthesis of aniline is because it's farr more expensive than the normal Reduction with Fe/HCl.
However i'm looking forward to investigate more these reactions and make a very detailed report of these," i what aniline god damn it " and its the only thing i have to do it. Ofcourse i say these but when i start to see that im running out of nitrobenzene then i will see to do the Fe/HCl xD xD
For the zinin reaction i have a lot of ideas, like think the hydrolysis of the sulfide ion is a key step im thinking on adding the sulfide solution dropwise in a time, and some other things, i will loke to do it and post.
I wish i could buy some Aniline :'(