Using Zn/HCl, Fe, Sn and other heavy metals as redusing agents in the case of nitroimidazoles offen makes a problems because this metals in molar quantity can form comlex with imidazole moiety. It is better to use catalitic ammounts of active metal and perform the redution in athoshere of hydrogen. The best systems is H2/Ni(Raney) or H2/Pd(on activated carbon). This reactions does not requer high temperature and generally can go under atmospheric pressure. But the equipment and the solvents (methanol or THF) have to be VERY pure, espesially witout any traces of S(II)  compounds, because such catalist can be very easily poisoned

Sir Kirill I. Petko,

Thank for your answer. I will try what you suggested.

Hydrogenation with 10% Pt on carbon, in acetic acid, works nicely at atmospheric pressure, and it's relatively immune to the usual poisons.

Dear Meltem Çorbacioğlu

Catalytic hydrogenation using Pd-C in abs. ethanol and or/methanol at 2 atm. might be effective.

Good luck

I am very grateful for your help. I will consider your advice.

You can use also Zn with drops of acetic acid and dichlorometano as solvent.

You can try the reduction with Hydrazine hydrate (98%), 10% Pd-C catalysis in MeOH under reflux. After filtration to remove the catalyst, solvent is distilled out. The crude product thus obtained is further purified by recrystallization. Time required is about 3-5 hours , Yields are excellent in general. The method works well specially for reduction of nitroindole, nitroinadazole, nitroimidazole derivatives. You can go through the reference Chakrabarty M, Kundu T, Arima S, Harigaya Y  Tetrahedron Lett 2005, 46, 2865. we have used the method in our lab too to reduce 1N- protected 5-nitroindazole and 5-nitroindole and 5-nitroimidazole derivatives in good yields.

Yes, as mentioned by Gandhi K. Kar, using Hydrazine hydrate (98%), 10% Pd-C catalysis in MeOH under reflux is recomended.

I believe that colleagues Gandhi K. Kar and  Talaat I. El-Emary nice display. The higher the yield from the use of Zn / HCl, although there is more work.

If you don't have any imine and carbonyl group in your compound Na2S2O4 is the best and easy reagent. You need to run the reaction in the nitrogen environment for 10 minutes.

Once I reduced aromatic nitro groups using iron powder and HCl. Yield was quite good. Only is that reaction may be a bit "uncomfortable": due to the presence of iron you cannot add magnetic stirring, you need to do hand-shaking continuously during all reaction.

Best regards

Iron- HCl is rather good system for nitro derivatives without NH or OH groups and it is exellent when the product can be isolated by the steam distillation. Howewer in the case of redusing of nitrophenoles, nitroanilines nitroindoles and nitroimidazoles this metod led to very small yields or (very often) to the very bad luck and fail

The sodium dithionite works well in the absence of carbonyl or imine functionality. But if your compound has got the carbonyl group, you may use stannous chloride (tin (II) chloride) and hydrochloric acid.

5 times of ethanol and 2 times of HCl and add 5 eq of Iron portion wise

Try hydrogenation using Raney Nickel and/ pd-charcoal.

you may try with stannic chloride 

Hydrazine can do this type of reduction too.

Also, using Zn/AcOH might be useful.

Reduction of aromatic nitro or nitroimidazole can successfully achieved by using H2/Pt catalyst in acetic acid as a solvent. Other reagents also reduce nitro compds. using of sodium sulphide or Fe in HCl.