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SHARMA ET AL.
are reported in acidic and alkaline media [4–18]. The
kinetics of oxidation of unsaturated alcohols such
as crotyl alcohol (CrA) by sodium bis[-2-ethyl-2-
hydroxybutanato(2-)] oxochromate(V) [19] has been
reported. The oxidation of crotyl alcohol in aqueous
methanol by N-bromosuccinimide [20] indicates rate
independence of the hydrogen ion concentration. The
oxidation of crotyl alcohol by Ce(IV) [21] ascribes
that the rate is directly proportional to the hydrogen
ion concentration.
Most of the kinetic studies of oxidation of un-
saturated alcohols have been made in the presence
of heterogeneous catalysts [22,23]. Also transition
metal ions such as Ru(III) [24], Os(VIII), Pd(III) [25],
and Ru(II) were employed as homogeneous catalysts.
There is an ambiguity regarding the oxidation product
of these unsaturated alcohols with metal ion oxidants
in solution.
carried out in glass stoppered Corning glass vessels,
which were thermostated in a water bath at 0.1°C
except mentioned otherwise. The reaction was initi-
ated by adding temperature preequilibrated solution of
peroxomonosulfate (heretofore written as PMS), and
the time of initiation was recorded when half of the
contents from the pipette were released in to the re-
action mixture, However, initiation of the reaction by
crotyl alcohol was without any effect on the kinetics.
An aliquot (5 cm3) of the reaction mixture was with-
drawn periodically and then discharged into a solution
of potassium iodide (ꢀ10%) prepared afresh. The lib-
erated iodine was titrated against thiosulfate solution,
employing starch as an indicator. Crotyl alcohol or its
oxidation product, however, was used without any ef-
fect on the iodometric estimation.
Initial rates (r, mol dm−3 −1) were computed [28]
s
employing the glass mirror method. Pseudo–first-order
plots were also made under conditions of ([crotyl al-
cohol] ꢁ 10 [HSO5−]). The rates in triplicate were
reproducible within 5%.
These were certain observations that prompted us
to undertake the kinetic study of the title reaction with
the purpose of finding out the kinetic pattern of oxida-
tion of crotyl alcohol by peroxomonosulfate apart from
identification of its oxidation products and dependence
of the rate on the hydrogen ion concentration.
Stoichiometry and Product Analysis
The stoichiometry of the reaction was determined by
taking excess concentration of peroxomonosulfate over
EXPERIMENTAL
that of crotyl alcohol keeping [H+] at 0.5 mol dm−3
.
Such reactions were allowed to occur in a thermostated
water bath at 40°C 0.1°C for ca. 6 h.; the excess
Materials and Method
Crotylalcohol (Acros) was employed as received with-
out any further treatment. The solution was prepared in
doubly distilled water and was kept in bottles painted
black from the outside to avoid any decomposition due
to diffused light.
peroxomonosulfate after ensuring completion of the
reaction was estimated iodometrically. These results
correspond to a reaction of a mole of peroxomonosul-
fate with a mole of crotyl alcohol as represented by
Eq. (1).
Peroxomonosulfuric acid is
a
triple salt
(KHSO5·K2SO4·KHSO4) and is commercially
known as oxone. It is a monosubstituted derivative of
H2O2. Peroxomonosulfate (Aldrich) was employed
as supplied, and its concentration was checked
iodometrically [26,27] with 96% content of peracid.
Other salts present to the extent of ꢀ4% did not have
any effect on the kinetics. All other reagents employed
in this study were of either AnalaR or GR grade
and were employed as received. Doubly distilled
water was employed throughout the study; second
distillation was from alkaline permanganate solution
in an all glass apparatus.
HSO−5 + CH3−CH=CH−CH2−OH
−→ CH3−CH=CH−CHO + SO−4 2 + H3O+ (1)
The stoichiometry was further confirmed by un-
dertaking kinetics of the reaction under stoichiometric
conditions. Second-order plots of 1/[HSO5−]t versus
time were made (Fig. 1, Table I), and the second-order
rate constants calculated from these plots were found
in agreement with the rate constants calculated from
other methods (Table I).
The oxidation product of the substrate was iden-
tified as croton aldehyde in two electron transfer.
The derivative of the product on addition of 2,4-
dinitrophenylhydrazine was prepared, and hydrazone
was confirmed spectrally.
Kinetic Procedure
The kinetics of the reaction was monitored by assaying
peroxomonosulfate iodometrically. The reactions were
International Journal of Chemical Kinetics DOI 10.1002/kin.21162