Oxidations With Nickel Peroxide (NICL2 + NAOCL)
Oxidations With Nickel Peroxide (NICL2 + NAOCL)
Oxidations With Nickel Peroxide (NICL2 + NAOCL)
OXIDATION
WITH NICKELPEROXIDE
1597
Although such metal oxides as manganese dioxide, selenium dioxide, lead dioxide, silver oxide,
mercuric oxide, etc. have often been used as
oxidizing agents in the field of organic chemistry,
the action of nickel peroxide as an oxidizing agent
on organic compounds has not yet been reported
in the literature except for a German patent1 in
which only the oxidation of toluene to benzaldehyde or benzoic acid was described. We have
studied the action of nickel peroxide2 on a variety
of alcohols in alkaline solution or in organic solvents and found that it is a convenient and useful
oxidizing agent for obtaining carboxylic acids or
carbonyl compounds from corresponding alcohols.
Nickel peroxide can readily be obtained by the
treatment of an aqueous solution of nickel sulfate
with sodium hypochlorite in an alkaline solution
and the activity is about 0.35 X 10-2 g.-atom of
available oxygen per gram.3 Since it has remarkably broad surface compared with its weight,
the available oxygen in nickel peroxide can be
used effectively in the reactions. Owing to this
character of the reagent, the oxidation of alcohols
with nickel peroxide can advantageously be completed in a short time with 1.0 to 1.5 equivalent
amounts of the oxidizing agent.
The oxidizing power of nickel peroxide for
alcohols was affected by alkalinity of the solvent
and temperature. While oxidation of alcohols by
this reagent in organic solvents afforded the corresponding carbonyl compounds, primary alcohols
in an aqueous alkaline solution were further oxidized to carboxylic acids. Therefore oxidation of
alcohols with nickel peroxide may be divided into
two procedures, determined by the presence or
absence of alkali in the reaction mixture.
Oxidation in Alkaline Solution.-With nickel
peroxide in an alkaline solution, saturated aliphatic
primary alcohols were oxidized to the corresponding
( 1 ) German Patent 127,388 (1900).
(2) Nickel peroxide is the name expediently applied to designate the
black, hydrous, higher oxides of nickel which are formed by reaction
between a strong oxidizing agent, such as one of the hypochlorites,
and freshly precipitated nickelous hydroxide, and its structure can
not be discussed in detail at present.
(3) A considerable portion of the available oxygen in nickel peroxide is lost gradually when it is heated, but if it is stored at room
temperature under protection against atmospheric moisture, activity
of the reagent remains unchanged for a long time.
acid in good yields, while the oxidation of straightchain alcohols proceeded more rapidly than that
of the branched-chain isomers. In the case of the
alcohols which are only slightly soluble in water,
for instance, octyl alcohol, the reaction proceeded
obviously a t a slower rate. Reaction rates of
oxidation of saturated aliphatic alcohols are listed
in Table I.
TABLE
I
REACTION
RATESOF OXIDATION^ FOR SATURATED
ALIPHATIC
ALCOHOLS
Alcohol
React.
Temp.
0.5
Time, Hr.
1.0
3.0
5.0
EtOH
30 O
96.6
97.3
99.4
n-PrOH
30"
74.9
93.0
96.6
n-BuOH
30'
81.6
94.1
96.9
i-BuOH
30"
47.8
59.1
72.7
84.9
i-BuOH
0"
19.6
20.1
29.0
40.3
30'
83.2
96.8
n-AmOH
i-hOH
30"
69.7
77.5
n-OctOH
30"
58.5
a All oxidations were carried out using nickel peroxide a t
1.5 times the theoretical amount, and the number in the
columns indicates per cent yields of the carboxylic acids.
1598
NAKAGAWA,
KONAKA,
AND NAKATA
YOL. 27
TABLE
I1
OXIDATIONU F SOMEAROMATIC
ALCOHOLS
Alcohol
Nickel
Peroxide4
Temperature,
OC.
Time,
Hr.
CH=CCHaOH
CeHsCH=CHCHZOH
CEH~CHZCH~CH~OH
1.1
2.0
1.5
50
30
0.5
6.0
10.0
CSHSCHZCHZCHZOH
1.5
30.0
CsH&HzOH
CsHsCHnOH
*CH&sH4CHzOH
O-CH~CEH~CHZOH
m-CH&sH4CHpOH
1.1
1.5
1.1
1.5
1.5
30
30
30
30
30
3.0
3.0
3.0
3.0
m-CHaCeH4CHIOH
1.0
7.0
p-CHsCsH4CHzOH
1.5
30
3.0
p-CHaCsH4CHzOH
1.0
7.0
a-Furfuryl alcohol
1.5
30
3.0
4.0
matography.
whereas at 30" it gave 56.7% yield of y-phenylpropionic acid and 17.6% yield of benzoic acid.
Benzylic alcohols were far more readily oxidized to carboxylic acids. Benzyl alcohol and
o-methylbenzyl alcohol, even employing only a
slight excess of the theoretical amount of nickel
peroxide, gave an excellent yield of benzoic acid
and o-methylbenzoic acid, respectively. Oxidation of m- and p-methylbenzyl alcohols was carried
out with an equivalent amount of nickel peroxide
at a low temperature and yielded the corresponding
acids along with the unchanged alcohols, but
when the reaction temperature was raised and
more peroxide was employed, it resulted in formation of dicarboxylic acids as by-product. On the
other hand, oxidation of o-methylbenzyl alcohol
with an excess amount of nickel peroxide did not
give any detectable amount of the dicarboxylic
acid, but afforded monocarboxylic acid as the
sole product.
The results of the oxidation of alcohols containing an aromatic nucleus in the molecule were
summarized in Table 11.
It has been reported that the oxidation of afurfuryl alcohol with acidic oxidants resulted in
the opening of the ring, and in the case of oxidation
with potassium permanganate4 the resulting afuroic acid was so contaminated that it was
hardly purified successfully. However, in the
oxidation with nickel peroxide at room temperature, a-furoic acid was readily obtained pure in a
good yield. The oxidation of aldehydes with
nickel peroxide afforded the carboxylic acids.
But, owing to alkalinity in the reaction mixture,
aldehydes bearing a hydrogen atom in its alphaposition resulted occasionally in the formation of
by-products as a result of aldol condensation.
(4) J. Volhard. Ann.. 161, 379 (1911).
Yield,
Product
CH=CCOOH
CsHsCH=CHCOOH
CEHSCH~CHZCOZH
CsHsCOzH
CsHsCHzCHzCOzH
50.0
81.0
;%;E\
7.5
93.0
96.7
92.0
97.0
40.2
5.9
60.0
0
62.5
12.0
81.0
0.
90.0
Yields were determined by quantitative gas chro-
MAY,1962
OXIDATION
WITH KICKEL
PEROXIDE
hydrazone, and the acidic by-products were titrated with 0.1 N sodium hydroxide solution.
The reaction turned out to give a very poor yield of
the carbonyl compounds and most of the available
oxygen in the oxidizing agent was lost as oxygen
gas. The results given in the Table 111 show
clearly that nickel peroxide cannot be regarded as a
reliable oxidizing agent for saturated aliphatic
alcohols in organic solvents.
OXIDATION OF
Alcohol
TABLEI11
SATURATED
ALIPHATIC
ALCOHOLS~
WITH
NICKELPEROXIDE^
Solvent
-Yield
-fo
Temp., Time,
Carbonyl
OC.
Hr.
Compd.; '70 Aoid,
'70
n-PrOH
Ether
25
12
3.2
0.18
Benzene
20
10
0.6
0.23
Ether
25
35
4.2
..
CPrOH
n-BuOH Ether
36
15
5.8
0.23
i-BuOH
Ether
36
32
6.2
0.20
a All oxidations were done with 50 g. of a 10% by weight
Nickel peroxide was used in an amount equivasolution.
lent to that of the alcohol. As 2,4dinitrophenylhydrazone.
1599
TABLE
V
COMPARISON
WITH MnO, FOR OXIDATION
OF BENZYL
ALCOHOL
Avail-
Oxydant'
able
oxygen/ Temp.,
ROHb
OC.
Time,
Hr.
Recovery of
Yield of
Benzaldehyde,
ROH,
MnOl
1.0
70
3
26.7
72.3
Nickel
peroxide 1 . 0
70
3
76.0
12.1
1.2
50
3
27.6
MnOt
Nickel
peroxide 1 . 2
50
3
90.8
0.9
MnO,
2.0
50
3
33.5
a Available oxygen content in manganese dioxide waa
determined by the method indicated in the case of nickel
peroxide. All oxidations were done in benzene solution.
Ratio of oxiduing agent to alcohol baaed on the available
oxygen.
..
..
NAKAGAWA,
KONAKA,
I N D NAKATA
1600
OXIDATION^
Niokel
Peroxided
Alcohol
Temp.,
OC.
OF
VOL.27
TABLE
VI
SOME
AROMATIC
ALCOHOLS
Time,
Hr.
Product
Yield,* %
Carbonyl Compd.
M . P . , "CSE
a-Phenylethyl alcohol
1.2
50
3
Acetophenone
50.7
250
Cinnamyl alcohol
1.2
50
1
Cinnamaldehyde
85.9
254
Benzoin
1.2
50
5
Benzil
98.3c
94
Benzhydrol
1.2
50
6
Benzophenone
98.16
48
o-Methylbenzyl alcohol
1.0
50
3
o-Methylbenzaldehyde
75.8
193
m-Methylbenzyl alcohol
1.0
50
3
m-Methylbenzaldehyde
57.7
211
p-Methylbenzyl alcohol
1.0
50
3
p-Methylbenzaldehyde
64.5
241
p-Methylbenzyl alcohol
2.0
50
3
p-Methylbenzaldehyde
81.0
241
a-Furfuryl alcohol
1.2
30
10
Furfural
77.8
216
P-Phenylethyl alcohol
1.2
80
1
Phenylacetaldehyde
12.9
236
?-Phenylpropyl alcohol
1.2
50
4
p-Phenylpropionaldehyde
11.6
259
a All oxidations were done in benzene solution.
Yields were calculated from weight of 2,4-dinitrophenylhydrazone.
Calculated from carbonyl compound itself.
Ratio of nickel peroxide to alcohol based on the available oxygen. * M.p.
of 2,4-dinitrophenylhydrazone. M.p. of carbonyl compound.
f
TABLE
VI1
YIZ?LDSIN PERCENT,FROM
V.A. Mg./15 M1.
Nickel
Peroxide M g .
Reaotion
Time, Min.
THE
OXIDATION
OF VITAMIN
Ala
150
100
50
so
25
25
10
100
67
33
50
50
50
50
100
20
50
250
167
84
10
69.7
11.7
20
72.8
14.8
60
20.4
30.7
50.6
65.0
82.7
25.5
66.3
81.5
77.4
72.5
120
24.2
34.2
56.6
74.6
65.0
80.1
78.1
72.5
180
26.1
38.4
66.2
76.5
67.9
a All oxidations were done in petroleum ether a t room temperature. The number in the columns indicates the per cent
yield. Method of assay: ultraviolet absorption.
Renewal of Nickel Peroxide.-After the oxidation reaction, nickel peroxide was collected by filtration, washed
with water, stirred with 6% sodium hypochlorite solution
(about ten times the quantity of nickel peroxide) for 20 min.,
filtered, washed with water, and dried.
Determination of Oxidation Rates for Saturated Aliphatic
Alcohols.-To a solution of 0.04 mole of each alcohol and 2
g. of sodium hydroxide in 100 ml. of water, nickel peroxide
(1.5times the theoretical amount) was added under stirring
on a magnetic stirrer, and the heterogeneous mixture was
allowed to react for the given times a t various temperatures.
The solid was then separated from the reaction solution by
suction filtration and washed with water. The combined
filtrate was acidified with dilute sulfuric acid and a portion
accurately weighed out from the solution was steam disExperimental
tilled. The volatile carboxylic acid in the distillate was
Preparation of Nickel Peroxide.-A mixture of 300 ml. of titrated with 0.1 N sodium hydroxide solution.
Oxidation of Benzyl Alcohol in Alkaline Solution.-To a
6% sodium hypochlorite solution and 42 g. of sodium hydroxide was added dropwise to 130 g. of nickel sulfate hy- solution of 2.16 g. of benzyl alcohol and 1.0 g. of sodium
drate in 300 ml. of water, and stirred for 0.5 hr. a t 20". hydroxide in 50 ml. of water, 16.0 g. of nickel peroxide (1.5
The resulting black nickel peroxide was collected by filtra- times the theoretical amount) was added while stirring on
tion, washed with enough water to remove active chlorine, a magnetic stirrer, and the heterogeneous solution was
and, after crushing the cake t o powder, dried over anhydrous allowed to react a t 30" for 3 hr. The reaction mixture was
filtered through a glass filter, nickel peroxide was washed
calcium chloride under reduced pressure.
Determination of Available Oxygen.-About 0.2 g. of with water, and, on acidifying, the filtrate deposited white
nickel peroxide weighed accurately was added to 20 ml. of needles which were collected and dried to give 2.1 g. of
36% acetic acid containing 2-3 g. of potassium iodide, benzoic acid, m.p. 122.5' (reported 122.4'), undepressed on
entirely dissolved, and allowed t o stand for 10 min. under admixture with an authentic sample. In addition, by
MAY,
1962
OXIDATIOW
WITH NICKELPEROXIDE
1601
Acknowledgment.-The
authors express their
thanks to Prof. S. Ueo and Dr. K. Takeda for
encouragement and helpful discussion.