A facile approach for the synthesis of magnetite microspheres with flower-like morphology is reported that proceeds via the reduction of iron (III) oxide under hydrogen atmosphere. The ensuing magnetic catalyst is well characterized by XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm and Mössbauer spectroscopy and explored for a simple yetbut efficient transfer hydrogenation reduction of a variety of nitroarenes to respective anilines in good to excellent yields (up to 98%) employing hydrazine hydrate. . The catalyst could be easily separated at the end of reaction using an external magnet and can be recycled up to 10 times without any loss in catalytic activity.

1. Synthesis of flower-like magnetite nanoassembly:
Application in the efficient reduction of nitroarenes
Kasibhatta J. Datta,+ Anuj K. Rathi,+ Pawan Kumar, Josef Kaslik, Ivo Medrik,
Vaclav Ranc, Rajender S. Varma, Radek Zboril* and Manoj B. Gawande,*
Regional Centre of Advanced Technologies and Materials, Department of Physical
Chemistry, Faculty of Science, Palacký University, Šlechtitelů 27, 783 71,
Olomouc, Czech Republic. †Both authors contributed equally.
*Email- manoj.gawande@upol.cz ; radek.zboril@upol.cz
This work has been published in Scientific report
Scientific Reports, 2017, 7, 11585

2. Abstract
A facile approach for the synthesis of magnetite microspheres with flower-like
morphology is reported that proceeds via the reduction of iron (III) oxide under
hydrogen atmosphere. The ensuing magnetic catalyst is well characterized by
XRD, FE-SEM, TEM, N2 adsorption-desorption isotherm and Mössbauer
spectroscopy and explored for a simple yet efficient transfer hydrogenation
reduction of a variety of nitroarenes to respective anilines in good to excellent
yields (up to 98%) employing hydrazine hydrate. The catalyst could be easily
separated at the end of reaction using an external magnet and can be recycled up
to 10 times without any loss in catalytic activity.

3. Figure 1. Schematic illustration of the synthesis of Fe3O4 nanoflower.

4. Figure 2. Evolution of X-ray diffraction patterns during in situ monitored thermally
induced transformation of iron(III) oxide with ultra-small particles to magnetite in
hydrogen gas atmosphere.

5. Figure 3. (a) XRD pattern and (b)
Mössbauer spectrum of magnetite.

6. Figure 4. (a) SEM and (b) TEM
image of magnetite.

7. Figure 5. N2 adsorption-desorption isotherm of magnetite.

8. Table 1: Magnetite catalyzed catalytic reduction of nitrobenzene
under microwave irradiation
Entr
y
Cataly
st
Amount of
catalyst (mg)
Hydrazine
hydrate ( L)
Temp.
(˚C)
Time
(Min)
bConver
sion (%)
bYield
(%)
1 ---- ---- ----- 90 30 0 0
2 ----- ---- 150 90 30 0 0
3 Fe3O4 30 ---- 90 30 0 0
4 Fe3O4 10 150 90 30 >97 95
5 Fe3O4 30 150 90 30 >99 98
6 Fe3O4 30 150 90 15 >99 98
7 Fe3O4 30 100 90 15 >99 98
8 Fe3O4 20 100 90 15 93 89
9 Fe3O4 30 60 90 15 >90 87
10 Fe3O4 30 100 50 15 35 25
11 Fe3O4 30 100 70 15 72 66
12 Fe3O4 30 100 90 10 >94 91
13 Fe3O4 30 -----c 90 15 0 ---- c
14 Fe3O4 30 100 90 180 99 97d

12. Figure 6. Reaction condition: Nitrobenzene (1 mmol), Hydrazine hydrate
(200 µL), Fe3O4 (60 mg), EtOH (3 mL), temperature (90 °C), MW.
Determined by GC using dodecane as an internal standard.

13. Figure 7. Schematics of (a) direct reaction route for reduction of nitroarene
to anilines and (b) mechanism of nitroarenes reduction over the surface of
magnetite via direct route using hydrazine hydrate as hydrogen source.
[V1]I have now cited this figure which was missing in the text