I'm looking at the reduction of nitrobenzene to aniline as a model system for my current project. Additionally, I'm looking into scaling up my current reaction. At the moment I'm using metallic tin in the reduction process, however, I've noticed that iron metal can be used instead. Iron would be beneficial because of its cost as compared to tin. Would the reduction reaction yield be the same if I were to switch from tin to iron metal? Or is there another set of parameters that I could use for my reduction process?
Yes, you can use iron with acetic acid or hydrochloric acid. Procedure is described in Vogel's textbook.
Yes, you can use iron with acetic acid or hydrochloric acid. Procedure is described in Vogel's textbook.
There are many recipes using an active metal and a hydrogen source. I remember doing this reaction by refluxing zinc dust and calcium chloride in methanol. I also have tried this reaction under other conditions. One difference I had was that I was trying to reduce dinitro compounds to diamines. The difficulty I had with my analogs was trying to isolating the final product. Sometimes the anilines would self polymerize into very expensive shoe polish (dark brown or black tar-like goop), this can still happen with monoamines. You may have to isolate your compound as the HCl salt, limit exposure to oxygen, and if your lucky to have an oil as final product, perform a distillation before use. Hope this helps.
Dear David
I came across similar questions recently: Catalytic hydrogenation over Palladium or platinum on chacoal or Raney nickel are the cleanest processes, if no double or triple bonds are present in the molecule. Benzylic amines and alcohols may have a better chance to survive with platinum. Aromatic halogens are also affected by hydrogenation, but there are "poisoned" versions that minimize this side-reaction from Degussa. I think you plans to use iron powder in acetic acid are great.
Dear David, As mark suggested you can use iron powder but i would like to add one of simplified process that you use iron powder (20 mole) in ethanol and instead of HCL you can use NH4CLin water (10 mole) at 50c and than as soon as reaction complete you just filtered through highflow and washed with DCM and dried on Na2SO4. and distilled off to get compound.
Dear David
You can used from Sodium dithionite. That is simple method
Urishibara nickel is a good Het. Hydrogenation catalyst, Can often get good turn over and high yields, reasonably cheap too.
based on the above suggestions, you may look into the following references to obtain quantitative yield:
Synthetic Communications, volume 33, Issue 5, 2003
pages 843-849 and Volume 27, Issue 17, 1997 pages 3047-3052
Use of H2/Pt is better catalyst for reduction of NO2 groupin to amino group.
The Yield and the purity is good
sodiumsulphite, TBAB and protic solvent also works very good.
According to my experience the best way to reduce nitrobenzene to aniline is reduction by activated zinc dust acetic acid in DCM.
Activation of Zn dust: 400 g Zn dust is taken in a flask 150 mL of 10% HCl aq. soln. was added stirred for 2 minute, filtered washed with 300 mL water followed by 100 mL acetone, dried in vacuum oven.
Procedure for reduction: To a stirred soln of nitrobenzene derivatives (A) (1 equiv) in DCM 5 mL/mmol of A) activated Zn-dust (50 equiv.) was added, cooled to 0 degree centigrade. AcOH (1.5 mL/ mmol of A) was added dropwise. Stirred for 10 min. (completion of the rxn to be checked by TLC analysis) at 0 degree, filtered through a pad of celite (DCM evaporated) and the celite was washed with EtOAc. The filtrate was neutralized with NaHCO3 soln. dried and purified by column. Try this method I think it will serve your purpose.
Fe/CaCl2. check this paper: Synlett 2010, No. 20, 3019–3022. this is a green and selective method
I have used both Zn and Fe powders to reduce aromatic nitro groups with satisfactory results. There are several references in March's 6th edition.
Best reduction of nitrobenzene to aniline is catalytic reduction using H2/Pt catalyst . Otherwise one can use Fe in HCl .
Iron with acetic acid is useful in getting sufficient yield of reduced product. The nitro group can also be reduced by heating with sodium sulphite and ammonia. The change in colour of the reaction mixture (yellow to colourless) is good indicator of completion of reaction in this case. However, the colour of reaction mixture changes rapidly to brown if not worked efficiently enough to convert it into its hydrochloride salt.
how do separate aromatic amine and aromatic nitro compound from the reaction mixture. the reaction mixture is in acidic medium.
If reaction medium is acidic, aniline should go into aqueous phase whereas nitro should remain in organic phase.
For reduction of nitrobenzene to aniline you can use cheaper catalyst Fe in conc. hydrochloric acid known as Bechamp reduction . This method is used for the reduction of nitro compounds to amines on an industrial scale,. than any other reduction reaction.
- Badges
- Science topic
- Similar topics
- Chemistry
- Organic Chemistry