In line with the outlined strategies, herein, we wish to introduce an easy, efficient and practical protocol for solvent-free reduction of various aromatic and aliphatic nitro compounds to the corresponding amines with NaBH4
in the presence of bis-thiourea complexes of bivalent cobalt, nickel, copper and zinc chlorides at room temperature (Scheme 1).
Let us consider the effect of the NaBH4
: AgNO3 weight ratio on the sol parameters.
To a magnetically stirred solution of dibromoindanone (2,4-dibromoindanone and 2,5- dibromoindanone) in THF/MeOH (8 ml/5 ml) was added a solution of NaBH4
At the same time, we put NaBH4
powder into NaOH solution in low concentration and stirred slowly to get colorless reducing solution.
The literature review shows that direct transformation of epoxides to 1,2-diacetates has been obtained in the presence of various catalysts/reagents such as HCl/ZnCl2 , BF3 Et2O , DBU/LiCl , n-Bu4NCl , n- Bu4NOAc , Bu3P , LiClO4 , Er(OTf)3 , HY zeolite , (NH4)3PMo12O40 , (TBA)4P- FeW11O39 3H2O , ZrO(OTf)2 , NaBH4
, phosphomolybdic acid or its supported on silica gel  and molecular sieves 4A .
Sodium tellurite ([Na.sub.2]Te[O.sub.3]) and 3-mercaptopropionic acid (HSC[H.sub.2]C[H.sub.2]C[O.sub.2]H) were procured from Aldrich Chemicals; cadmium chloride (Cd[Cl.sub.2] x 5[H.sub.2]O), sodium borohydride (NaBH4
), and trisodium citrate dihydrate ([C.sub.6][H.sub.5][Na.sub.3][O.sub.7] x 2[H.sub.2]O) were acquired from Merck.
The hydrolyzate was repeatedly co-concentrated with methanol, reduced with NaBH4
for 30 min at 20 oC and acetylated with acetic anhydride and pyridine at 100 oC for 20 min.
The salts were reduced to metallic nanoparticles by the addition of 2.0 g of NaBH4
. The nanoparticle product was then isolated through centrifugation and sequentially washed with water, ethanol, and acetone (20 mL of each).
Catalysts such as BF3.Et2O, Al2O3/P2O5, NaBH4
, PPA/SiO2, AcOH/MW, MgO/POCl3 have been used to increase the reaction efficiency .
The reducing agent, NaBH4
, is added dropwisely under Ar.
A 1.0% (m/v) NaBH4
solution was prepared by dissolving NaBH4
in 0.5% (m/v) NaOH solution.
Then the Ni NPs were obtained by in-situ reduction in the presence of sodium borohydride (NaBH4