JournaloftheChineseChemicalSociety, 2004, 51, 569-570
569
ReductionofAromaticNitroCompoundsunderSolvent-freeConditions
usingAlumina-supportedHydrazine/FeNH
4
(SO
4
)
2
·12H O
2
a
a
b
Chang-rui Zhang (
), Yu-lu Wang * (
) and Jin-Ye Wang (
)
a
SchoolofChemistryandEnvironmentalScience,HenanNormalUniversity,Xinxiang,453002, Henan,
P. R. China andTheKeyLaboratoryofEnvironmentalScienceandTechnologyofHigherEducationof Henan
Prov ince, P. R. China
b
ShanghaiInstituteofOrganicChemistry,ChineseAcademyofSciences,Shanghai,200032,P. R. China
Ar o matic ni tro com pounds were eas ily re duced to the cor re spond ing amino com pounds with hydrazine
hy drate sup ported on alu mina in the pres ence of FeNH
4
(SO
4
)
2
ž12H O.
2
Keywords: Reduction; Hydrazine hydrate; Aromatic ni trocompounds; Amino compounds; Mi cro-
wave heating; FeNH (SO ž12H O.
4
4
)
2
2
INTRODUCTION
4 4 2 2
ported on alu mina in the pres ence of FeNH (SO ) ž12H O.
All the prod uctswere char ac ter ized by com par i son of their
TLC, IR spec tra and melt ing or boil ing points with au then tic
sam ples. The re sults of the re duc tion are sum ma rized in Ta-
ble 1.
Ar o matic amines are widely used as in ter me di ates for
dyes,photographicmaterials,pharmaceuticalandagricul-
turalchemicals,andasantioxidants.Hence,particularlyim-
menseinteresthasbeendirectedtowardthesynthesisofthese
compounds.Reductionofaromaticnitrocompoundsisoneof
the im por tant routes to pre pare them. It has been re ported that
an ecofriendly al ter na tive to the com monly used re duc tion
meth ods ef fected by means of iron and acid or sulphides is the
useofhydrazinehydrateashydrogendonorinthepresenceof
Scheme I
H2NNH2 H2O, FeNH4(SO4)2 12H O
NO2
2
NH2
R
MW
R
1
2
1
heterogeneous catalysts such as activated zinc-copper,
2
3
4-6
4-5
5,7-9
2 2
(a) R = o-NH ; (b) R = p-NH ; (c) R = m-OH;
Zn-C, Fe-C, Pd-C, Pt-C, RaneyNi,
FeCl
3
ž9H
2
O-
17
1
0-13
14-16
(
d) R = o-OH; (e) R = m-OCH
3
; (f) R = p-Cl;
activated carbon,
Fe(III) ox ides,
Fe(III)-MgO,
1
8
19
3
(g) R = p-CH ; (h) R = p-OCH
graphite and clays. How ever, most of the pro cesses men-
tioned above have one or more draw backs, such as long re ac-
tiontime,relativelyexpensivecatalysts,andatediouswork-
up.Consequently,easy,rapid,convenientmethodsforthere-
ductionofaromaticnitrocompoundsarerequired.
3
Hydrazinehydrate,knownasanexcellentreducant,has
been em ployed in many re ac tions. It has been re ported that
2
+
20
with some cat a lysts (such as Cu ), reductionofsymmetri-
cal mul ti ple bonds pro ceeded readily, whereas re ac tion of
morepolarfunctionswereratherdifficult.Themethodsmen-
tioned above il lu mi nated that hydrazine hy drate is a good
reductant for ar o matic ni tro com pounds. Fur ther work is in
prog ress to un der stand the mech a nism of the re ac tions over
thesecatalysts.
RESULTSANDDISCUSSION
Microwaveirradiationhasbeensuccessfullyappliedin
organicsynthesis.Recently,reactionsfacilitatedbymicro-
waves un der sol vent-free con di tions have at tracted more at-
tentionbecauseoftheirenhancedselectivityandmilderreac-
tion con di tions. Recyclability of the in or ganic solid sup port
isoftenpossiblethusrenderingtheprocedurerelativelyenvi-
ronmentallyacceptable.Inthisway,wesuccessfullyreduced
the ar o matic ni tro com pounds with hydrazine hy drate sup-
EXPERIMENTAL
Ar o matic ni tro com pound (1 mmol), alu mina (1.5 g)
and FeNH (SO ) ž12H O (1.2 g) were mixed thor oughly in
4 4 2 2