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Page 73
Industrial Chemistry | ISSN: 2469-9764 | Volume 4
17
th
International Conference on
May 21-22, 2018 | New York, USA
Industrial Chemistry and Water Treatment
Ind Chem 2018, Volume 4
DOI: 10.4172/2469-9764-C1-009
Kinetics and mechanism of periodate oxidation of two ternary nitrilotriacetate chromium (III)
complexes involving histidine and aspartate co-ligands
Mohamed A Habib
Sirte University, Libya
T
he oxidation of [Cr
III
(HNTA)(Hist) (H
2
O)]- and [Cr
III
(HNTA)(Asp)(H
2
O)]- (NTA=nitrilotriacetate, Hist=L-histidine and
Asp=DL-aspartate) by periodate in aqueous medium has been studied spectrophotometrically between 15.0 and 35.0°C
under pseudo-first-order conditions, [IO
4
]- [complex]. The rate increases over the pH range 3.40-4.45 in both cases, but the
two complexes give different rate laws, in aqueous solutions, [Cr
III
(HNTA)(Hist)(H
2
O)]- is oxidized by IO
4
- according to the
following rate law: d[CrV
I
]/dt =(k
1
K
2
+k
2
K3K
1
/[H+])[IO
4
-][Cr
III
]T/{1+ (K
1
/[H+]) +(K
2
+K
1
K3/[H+])[IO
4
-]}. The other case
is [Cr
III
(HNTA)(Asp)(H
2
O)]- the derived rate law is given by equation: Rate=k
1
K
2
[Cr
III
]T[I
VII
]T/{1+ ([H+]/K
1
) + K
2
[I
VII
]T}.
Electron transfer, outer-sphere and inner-sphere mechanisms have been discussed. The nature, properties, chemical behavior
and different species in aqueous solutions of periodate have been reported. A literature survey on the oxidation of organic
and inorganic compound in aqueous solutions and in aqueous organic solvent was reported. The nature of α-amino acids and
their metal complexes have been briefly discussed, it is clear that [Cr
III
(NTA)(Asp)(OH)]
2
- may be the reactive species, an
inner-sphere process may be still accommodating through replacement of coordinated H
2
O in two species by IO4-. The rate of
reaction increases with the increasing of complex concentration and ionic strength. The thermodynamic activation parameters
were calculated, and we propose that electron transfer proceeds through an inner-sphere mechanism, via coordination of IO4-
to chromium (III). A common mechanism for the oxidation of some to chromium(III) complexes by periodate is proposed by
an excellent isokinetic relationship between and values for these reactions.
MohamedHabib952@gmail.com