TotmhedronLetton lo. 3, pp 343 - 346,1972. Pergamn Psr.88. printed In eo8t Bzitaill.
REDUCTION
OF
CRGANIC
REDUCTION
Shionogi
(boei=d
Thiourea
thiourea
Research Labomtory,
Shionogi
dioxide
13 Wbor
peroxide
ions to metals.
production
of synthetic
We have studied
ketones.
Aliphatic,
reagent
in gocd yield
A typical
ethanol,
0.02
alicyclic,
experiment
concentrated
on silica
and fluorenol
1.74
aromatic,
briefly
ALCOHOLS
Fukushima-ku,
is easily
Osaka,
prepared
to hydrcquinones
dioxide
on a variety
and heteroaromatic
ketones
solution
was heated
for two hours at 90*
was obtained
not reduced.
from corresponding
reduced
of caustic
with
in 30 ml of
mole) of thiourea
on a water
bath.
dioxide
After
in benzene
was recovered
the yield
was reduced
thiourea
to 47.8Sr:
was
ond chromatogmphed
from the first fmction
When
this
alkali.
was dissolved
g (2.8%)
of
and hydrazo
with ether and the extract
from the next fmction.
to fluorenone,
azo,
was extracted
The crude product
0.05
agent in the
mole) of fluorenone
g (0.01
many kinds
of ketones and found that it
can be easily
g (0.01
and 1.08
azoxy,
alcohols
in the presence
of 1.80
in 20 ml of water
nitro,
of
the reduction
but ketones were
secondary
fluorenone
respect
that aromatic
1~1)
of reducing
has been used as a bleaching
reported
the aqueous solution
the solvent.
Japan
by the oxidation
agent capable
agent for obtaining
and the mixture
Unreacted
a half molar amount with
which
To a solution
is as follows:
g (95.6%)
Ltd.,
dioxide
of thiourea
reducing
by distillation,
to remove
gel (80 g).
thiourea
Gore
mole of sodium hydroxide
of ethanol
II, Co.,
acid)
using an aqueous ethanolic
were added under stirring
removal
yean
the action
and economical
I.
and Kyoii Minami
to the amines and quinones
in detail
SECONDARY
DIOXIDE.
but there have been only two reports (2) concerning
compounds by this reagent.
compounds were reduced
THIOUREA
has been known to be a reducing
fn recent
fibers,
WITH
l971;nooivud inu~ rorplruioation
29 tiou&
(1) (formamidine-sulphinic
with hydrogen
is a convenient
TO
Nakagawa
of metallic
organic
KETONES
Kunio
Jw-
ia.
OF
COMPOUNDS
dioxide
eluted
was used in
and unchanged
ketone
was recovered.
Genemlly,
reduction
of ketones were carried
out successfully
343
with
1 .O to 3.0
molar amounts of
lo.
thiourea
dioxide
using sodium hydroxide
reaction
mixture,
Considering
almost theoretical
these resulk,
in twice
molar amounts to that of the reducing
amounts of sodium sulphite
this reaction
+
The reducing
power of thiourea
with thiourea
dioxide
Reduction
by-products.
a dimer,
For example,
for example
dioxide
proceeded
agent was employed,
alcohol
gz2.0033,
aH = 3.3G
spectrum was identical
Considering
tmnsfer
reduction
ta take place
agent
of aliphatic
occasionally
resulted
ketones,
in the reaction
of the reagent
of the
ketone
or di-n-propyl
of the alcohol
when more reducing
portions,
the yield
of the
proceeded
through a radical
solution showed the presence
aH = 2.6G
(2H),
oH = 0.7G
on reduction
the reduction
way
in Table.
it becames clear
frcm ESR studies and fram the reaction
reaction
ESR studies on the
of the corresponding
(2H),
with Rongalit
and aH = 0.4G
of the secondary
onion mdical,
(2H).
This ESR
(NaHSQ.CH20.2H20).
may possibly be explainable
of formation
path.
in terms of a one electron
alcohol
of
of its side chain
gave a poor yield
into seveml
yield
in the formation
cleavage
However,
of fluorenone
36%.
resulted
methylnonyl
mixture.
divided
in yield
in partial
slower rate and the reaction
of fluorenane,
and the mechanism
in the following
by alkali
of benzoylacetone
with that obtained
these results,
but the reduction
as a by-product
of ketones were summarized
in alkaline
(2H),
by excess of alkali,
sq--
increased.
that the reaction
of fluorenone
decomposed
at a noticeably
In the course of the reduction
products obtained
+
in a molar ratio of 1 : 1 did not give a satisfactory
The reduction
and the addition
was morkedly
,c=o
+
C 9,9’-bifluorenonel-9,9’-diol,
of the reducing
The results of the reduction
reduction
)CH~H
was not affected
the reduction
carbinol.
owing to decomposition
secondary
e
of ketones which are easily
to give phenylmethyl
ketone
2OH-
and sodium hydroxide
but afforded
scheme.
‘WJ,
)c=o + HZN\
,C-SQ-
alcohol,
From the
and urea were obtained.
is presumed to be in the following
+
agent.
ond the dimer is presumed
5
Table
Reaction
Ketone
time
(hr)
Molar
(thiaurea
mtio
dioxide
to ketone)
Yield
06)
Fluorenone
2
1 .o
95.6
Benzophenone
6
1.8
100.0
6
1.8
99.0
Acetophenone
6
1.8
l94.4
Propiophenone
6
1.8
l93.3
Di benr yl ketone
2
1.8
96.7
Reruylmethylketone
6
1.8
l
3-Benzoylpyridine
6
1.8
100.0
8-Acetonaphthone
6
2.4
91 .l
a-Methylaminoacetophenone
2
3.0
78.0
Cyclohexonone
6
1.8
80.9
Methylnonylketone
7
2.4
*74.2
Di-n-propylketone
6
2.4
‘75.5
Desaxybenzoi
l
Yields
n
were determined
a)
All
b)
Sodium hydroxide
reduction
by quantitative
were done in dilute
gas chramatagraphy.
alcohol
solution
ot 90’.
was used in twice molar amount of thiourea
dioxide.
97,3
Ilo. 5
REFERENCES
1.
B. Banett,
2.
S. Takagi,
l9&
1355.
J.
Chem.
Chem.
Soc.,g,63
Pharm.
Bull.
(1715).
(Japan),
U.S.P.
,615
2,150,921,
(1957);
2,347,446,
P. H. Gore,
2,783,272.
Chemistry
8, Industry,