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Патент USA US2130151

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I‘ 2,130,151
Patented Sept. '13, 1938
UNITED STATES PATENT OFFICE
2,130,151
PRODUCTION OF QUINONE AND HYDRO
QUINONE
Herbert Palfreeman, Manchester, and Norman
Victor'Sydney Knibbs, Kent, England
‘
No Drawing. Application‘December 12, 1934, Se
rial N0. 757,236. In Great Britain December
16, 1933
9 Claims. (C1. 204-9)
This invention relates to the production of
quinone (p-benzoquinone) and hydroquinone
(1.4 dihydroxy-benzene) .
'
It is known that when benzene, agitated with
exceed 25° C. and ‘ordinarilya temperature ‘of
20° C. is a suitable temperature at which to
operate. ‘Temperatures higher than 25° C. do not
give a good yield. Although temperatures lower
phuric acid which is maintained cool, is elec
than 20° C. may be used they do not possess
any advantage to compensate for the extra cost of
trolyzed between electrodes which are unattacked
by the electrolyte e. g. lead electrodes, the benzene
is partially converted into quinone at the anode.
Since quinone is soluble in water and in aqueous
solutions and is cathodically reduced to hydro
quinone it has been usual to carry out the oxida
ode as described hereafter.
The anode may be of lead or an alloy of lead.
5 a neutral or acid electrolyte, for example sul
cooling and the higher cell voltage which lower
temperatures entail. The temperature may be
maintained within the required limits by the pas
sage of cold water through a coil serving as cath 10
tion in a cell divided into two, by a porous dia- ' Its surface becomes coated with lead peroxide
phragm so as to avoid the wastage of current by when current is passed and the condition of this >
15 the passage of quinone and hydroquinone between
the electrodes.
coating of peroxide in?uences the e?iciency of
the formation of quinone. It has been found that
‘
An object of this invention is to provide an
the peroxide coating should not be too thick and
improved process for the production of quinone by
should not be of such a nature as to scale off
anodic oxidation.
of lead with antimony or an alloy of lead with 20
bismuth forms a more stable peroxide surface
and that a hard lead alloy for example an alloy
.
20
A further object of this invention isto provide
an improved process for the production of hy
droquinone from the dilute solution of quinone in
benzene obtained by the anodic oxidation process
of the invention.
25
It has been found according to this invention
that a high yield of quinone can be obtained with
out the use of a diaphragm, the disadvantages of
which are well known.
_
According to the process of this invention for
30 the production of quinone, ‘benzene is passed
through or stirred with an electrolyte preferably
consisting of dilute sulphuric acid or a mixture of
sulphuric acid and a soluble sulphate such as
sodium sulphate, and subjected to electrolysis in
35 an electrolytic cell‘ in which an active and stable
anode and an inactive cathode are disposed pref
than pure lead.
-
The anode surface may be rendered active and
stable by the passage of an alternating current
25
or an alternating current superimposed on a di
rect current through the cell in the absence of
the cathode and before the introduction of the
benzene, or in another cell.
Thus, for example, the electrode to be used
together with a similarly shaped piece of lead 30
may be disposed in an electrolytic cell, the elec
trolyte being dilute sulphuric acid. Electric cur
rent is passed through the cell, the direction of
the current being frequently reversed by means of
a suitable switch. The last change of currentis 35
e?'ected so that a coating of lead peroxide is
erably close to each other, the concentration of formed on the electrode to be used.
quinone in the cell being kept low by its con-_ _ The anodic current density may vary between
tinuous or frequent removal.
40
\
The electrolyte is preferably dilute sulphuric
acid and it maybe of any concentration up to
20% of H2804. Too low an acid concentration
results in an electrolyte of low electrical con
ductivity, while too high a concentration results
in the destruction of quinone. An acid con
centration of 10% of H2804 has been found to be
satisfactory.
The addition to the electrolyte 0.? acetic acid
or other organic acids or salts of organic acids
has been proposed for the purpose of increasing
, _ the solubility of the benzene in the electrolyte.
We have tried these additions but have found
that they do not increase the ei?ciency of the
process.
The temperature of the electrolyte should not
fairly wide limits but it has been found that
densities of between 5 and 15 amperes per square 40
decimetre give the best results.
‘
The cathode may be of any metal that is
unattacked by the electrolyte but metals such
as copper which promote ‘the reduction of
quinone should be avoided. Lead is a satis 45
factory metal to use as the cathode.
The cath-
, ,
ode. is maintained in an inactive condition by
taking care that the current is never allowed to
flow in the direction opposite to the normal.
> This means thatvthe anode activation process 50
should be carried out apart from the cathode,
as hereinbefore indicated.
‘
.
‘
.
.
‘ . Itvhas also been found that to maintain quinone
reduction at a‘ minimum ‘the cathode should ‘be
the coolest part of the cell, and therefore, water
/
2 .
2,130,151
for cooling is passed through the cathode which
may conveniently consist of a lead coil.
High cathodic current density is accompanied
by low reduction of quinone and the cathodic cur
rent density should therefore be higher, prefer
ably at least 50% higher, than the anodic cur
rent density. In other words the area of the oath
ode should be less than that of the anode.
The electrolyte is preferably covered with a
10 layer of benzene which is stirred into the elec
trolyte by means of a suitable agitator. The
agitation should be sufficient to ensure constant
circulation of benzene around the whole of the
anode, but it should preferably be not so violent
15 as to cause ?ne emulsi?cation of the benzene with
consequent slow separation of the benzene and
electrolyte. Fresh benzene is added continuously
or at intervals and an equivalent volume of ben-‘_
zene-quinone solution is withdrawn from the cell
20 for example by over?ow. The feed and overflow
should be adjusted to prevent the concentration of
quinone in the benzene from rising above 15
grams per litre. This prevents the quinone con
centration in the electrolyte from rising above
25 about two grams per litre.
Some benzene is lost from the cell, being car
ried away by the stream of mixed gases evolved,
this loss may be partly avoided by the use of a
suitable condenser which may be maintained at a
30 su?iciently low temperature to freeze out the
benzene. The stream of mixed gases may alter
natively be made to pass through a known ab
the cell may be treated with iron borings and
water containing a little sulphuric or other suit
able acid in a heat jacketed or otherwise heated
vessel.
The vessel with the contents are kept at a tem
perature of about 80° C., the benzene solution is
run in slowly, the benzene distills over and is con
densed, and the quinone is entirely reduced to
hydroquinone which remains in the vessel in
aqueous solution. The acid liquors from the ves 10
sel are occasionally withdrawn and the hydroqui
none recovered therefrom. Preferably the hot
saturated liquors are drawn oil’, ?ltered hot and
cooled when hydroquinone crystallizes out. The
acid mother liquor is returned to the reduction 15
vessel. The hydroquinone may be recrystallized
from water or other solvent.
Alternatively the aforesaid quinone-benzene
solution may be run into a still containing water
into which sulphur dioxide is simultaneously led 20
in amount equivalent to that of the quinone to
be reduced. The benzene distils off and is con
densed and the hydroquinone formed remains
behind in solution in the water together with the
sulphuric acid formed in the reaction. At inter
vals the aqueous solution is withdrawn the acid
removed by means of calcium carbonate, lime or
barium carbonate or hydroxide and the hydro
quinone obtained by evaporation. By using an
iron free distillation vessel the hydroquinone may 30
in this way be obtained absolutely free of iron.
The following example illustrates how the proc
sorbent and afterwards recovered therefrom, or a _ ess of the invention may be carried into effect:
combination of cooling and an absorbent may be
35
used.
.
The benzene which is oxidized to quinone may
contain dissolved therein phenol and/or aniline
which are easily oxidized to quinone during the
course of the reaction. If desired regulated quan
40 titles of aniline and phenol may be added to the
benzene during the reaction.
If quinone is required as a ?nal product it may
be separated from the benzene by known meth
ods, for example by distilling off some of the
45 benzene and crystallizing the quinone. As here
inbefore indicated, however, the quinone may be
converted into hydroquinone which as is known is
extensively used for photographic purposes.
Several methods have been proposed for the
50 production of hydroquinone. For example it has
been proposed that a benzene solution of quinone
' should be added to the cathode compartment of a
divided electrolytic cell, or that it should be agi
tated with water and sulphur dioxide.
In both these proposed processes quinhydrone
55
is ?rst formed, and its low solubility makes its
further reduction to hydroquinone slow and di?i
cult. Also it tends to collect at the interface of
the liquid phases and to cause stable emulsi?ca
60 tion of the benzene in the water.
According to the process of this invention for
the production of hydroquinone the benzene solu
tion of quinone produced in the manner herein
before described is subjected to reduction at about
65 the boiling point of benzene and under such con
ditions that the benzene is immediately distilled
011‘ and the hydroquinone dissolved in water.
The reduction may be carried out by means of
iron and acid, sulphurdioxide or other known
70 reducing agents. Quinone is rapidly destroyed at
‘these temperatures so the conditions must be
such that reduction is rapid and complete and
the benzene solution must be added gradually
to the reduction vessel.
75 Thus a solution of quinone in benzene run from
The cell employed is capable of operating at
1000 amper'es. The anode consists of an alloy of
lead containing 10% of antimony made in tubu
lar form with leads attached to carry the current.
The whole of the tubular sheet is freely perfo
rated so that under agitation the benzene passes
freely through it. This electrode has a total 40
surface area of 125 square decimetres, the diam
eter being about 40 centimetres. The cathode
consists of a lead pipe of outside diameter 2.5
centimetres and 1100 centimetres long made in
the form of a coil of 44 centimetres internal di 45
ameter suitably stiffened. The cell container
of glazed earthenware or other suitable inert ma
terial has a capacity of about 100 litres and has
a bottom outlet and an overflow pipe near its
upper edge.
A lid of suitable form to make a 50
tight joint is provided and the cell is charged
with 85 litres of sulphuric acid containing about
100 grams of H2804 per litre.
Current is then
passed until the anode which has been activated
is coated with lead‘ peroxide, after which 15 litres 55
of benzene are added. The cell agitator is intro
duced through a central hole in the lid and op
erates inside the anode cylinder. The agitator
is of aluminium having six blades which when
rotated carries the benzene downwards through
the electrolyte but does not give ?ne emulsi?ca
tion. The electrolyte covers the whole of the ef
fective electrode surface and the top blade of the
agitator is just immersed in the electrolyte. The
addition of 15 litres of benzene allows the passage
of about 1000 ampere hours before the concentra
tion of quinone in the benzene attains a value of
about 10 grams per litre. At this point the ben
zene feed to the cell is started at the rate of about
15 litres per hour. Cooling water is passed 70
through the cathode coil in sufficient volume to
maintain the temperature of the electrolyte at 20°
C. The benzene over?ow level is ?xed so that 15
litres of benzene remain in the cell, the overflow
being led to a still for the separation of p-benzo 75
3
2,130,151
quinone or to a reduction vessel. This vessel is a
cast iron still of 16 litres capacity, ?tted with an
agitator which nearly touches the bottom and
which is rotated at a speed of about 60 R. P. M.
The pipe leading in the benzene-quinone solu
tion reaches as nearly as possible to the bottom
of the still. The still is heated by a steam jacket
and ?tted ‘with a suitable condenser, the tem
perature is adjusted so that the benzene is im
10 mediately distilled over. The vessel is charged
with 1.5 kilograms of iron borings together with
4 litres of water and 1 to 2 grams of sulphuric
or acetic acid. The cell operating at 1000 am
peres maintains an over?ow of about 15 litres of
15 benzene-quinone
solution which continuously
passes to the reduction vessel. The benzene be
ing- distilled, condensed and separated from any
water which may distil over, is returned to the
feed vessel of the cell. The quinone is completely
20 and e?iciently reduced to hydroquinone which
dissolves and accumulates in the acid water con
tained in the reduction vessel. This vessel is
maintained at a temperature of about 80° C. and
the reduction carried on until the solution of hy
droquinone is. saturated at a temperature of about
60° C. when it is‘run off through a ?lter to re
move iron oxide. The ?ltrate is allowed to cool
and the crystallized hydroquinone separated by
?ltration. The acid mother liquor is returned to
the reduction still together with any water sepa
rated from the benzene distillate.
The cell is kept in'continuous operation main
taining theconditions set forth until the elec
trolyte becomes fouled with oxidation products
35 of benzene which dissolve in the electrolyte which
is then discarded. The cellyalso at times needs
cleaning owing to the separation of matter which
'is insoluble in both the electrolyte and the hen
zene but this will not occur at more frequent
intervals than after a continuous run of 24 hours.
The cell under the conditions stated produces‘
quinone with a consumption of power of about
10 kilowatt hours per pound of quinone. The
comprising subjecting a material selected from
the group consisting of lead and alloys of lead
to the passage of an alternating current super
imposed on a direct current in an acid electrolyte
to form an active and stable anode, electrolyzing
a mixture containing benzene and an electrolyte
by means of direct current passed between said
active and stable anode and an inactive cathode
without the use of a diaphragm, removing re
sultant quinone as a solution in benzene and 10
supplying more benzene to the cell, and so
adjusting such removal and supply as to keep
the quinone concentration of said solution rela
tively low.
3. A process for the production of quinone 15
comprising subjecting a material selected from
the group consisting of lead and alloys of lead
'to the passage of an alternating current in an
acid electrolyte to form an active and stable
anode, electrolyzing a mixture containing ben
zene and an electrolyte by means of direct cur
rent passed between said active and stable anode
and an inactive cathode without the use of a
diaphragm, removing resultant quinone as a
solution in benzene and supplying more benzene
to the cell, and so adjusting such removal and
supply as to keep the quinone concentration of
said solution from exceeding 15 grams per liter.
4. A process for the production of quinone
comprising subjecting a material selected from 1
the group consisting of lead and alloys of lead
to the passage of an alternating current in an
acid electrolyte to form an. active and stable
anode, electrolyzing a mixture containing ben
zene and a solution containing sulphuric acid by
means of direct current passed between said
active and stable anode and an inactive cathode
without the use of a diaphragm, removing re
sultant quinone as a solution in benzene and
supplying more benzene to the cell, and so ad
justing such removal and supply as to keep the
quinone concentration of said solution‘ relatively
low.
5. A process for the production of quinone
comprising subjecting a material ‘selected from 45
the group consisting of lead and alloys of lead
slightly discoloured but if this product is again to the passage of an alternating current in an
crystallized from water after being treated with ‘ acid electrolyte to form an active and stable
a small quantity of decolourizing carbon it gives anode, electrolyzing a mixture containing ben
zene and a solution containing sulphuric acid and 50
a
50 product which has the theoretical melting point. > a soluble sulphate by‘means of direct current
If desired the hydroquinone may be extracted
with ether or other organic solvent to obtain a passed between said active and stable anode
yield of hydroquinone from the quinone produced
45 is nearly theoretical.
The hydroquinone ob
tained from the ?rst crystallization may be
pure product.
and an inactive cathode without the use of a
'
The process described in the foregoing example
55 may be e?‘ected in the presence of aniline and/or
phenol but it should be conducted in such a way
that the concentration of aniline does not exceed
5 grams per litre and the concentration of phenol
does not exceed 1 gram per litre in the electrolyte.
What we claim is:-'
1. A process for the production of quinone
comprising subjecting a material selected from
the group consisting of lead and alloys of lead
diaphragm, removing resultant quinone as a
solution‘ in benzene and supplying more benzene 55
to the cell, and so adjusting suchremoval and
supply as to keep the quinone concentration of
said solution from exceeding 15 grams per liter.
6. A process for the production of quinone
comprising subjecting a material selected from
the group consisting‘ of lead and alloys of lead
to the passage of an alternating current in an
acid electrolyte to form an active and stable
anode, electrolyzing a mixture containing ben
to the passage of an alternating current in an "zene and an electrolyte by means of direct cur
acid electrolyte to form an active and stable rent passed between said active and stable anode
anode, electrolyzing a mixture containing ben
zene and an electrolyte by means of direct cur
rent passed between said active and stable anode
and an inactive cathode without the use of a
and an inactive cathode. said anode and said
cathode being disposed close to one another and
with no intervening diaphragm, removing re
sultant quinone as a solution in, benzene and
70 diaphragm, removing resultant quinone as a
solution in benzene and supplying more benzene supplying more benzene to the cell, and so ad
to the cell, and so adjusting such removal and , justing such removal and supply as to keep the
supply as to keep the quinone concentration of quinone concentration of said solution relatively
said solution relatively low.
_
2. A process forv the production of quinone
low.
'
_'7._ A process for the production of quinone If
2,130,151
comprising subjecting a hard lead alloy to the
passage of an alternating current in an acid
electrolyte to form an active and stable anode,
electrolyzing a mixture containing benzene and
an electrolyte by means of direct current passed
between said active and stable anode and an in-v
active cathode without the use of a diaphragm,
removing resultant quinone as a solution in ben
zene and supplying more benzene to the cell, and
10 so adjusting such removal and supply as to keep
the quinone concentration of said solution rela
tively low.
8. A process for the production of quinone
comprising subjecting an alloy of lead and a ma
15 terial selected from the group consisting of anti;
mony and bismuth to the passage of an alternat
ing current in an acid electrolyte to form an
active and stable anode, electrolyzing a mixture
containing benzene and an electrolyte by means
of direct current passed between said active and
stable anode and an inactive cathode without the
use of a diaphragm, removing resultant quinone
as a solution in benzene and supplying more ben
zene to the cell, and so adjusting such removal
and supply as to keep the quinone concentration
of said solution relatively low.
9. A process for the production of quinone
comprising subjecting a material selected from
the group consisting of lead and alloys of lead
to the passage of an alternating current in an
acid electrolyte to form an active and stable
anode, electrolyzing a mixture containing ben 10
zene, an electrolyte and at least one substance
selected from the group consisting of phenol and
aniline by means of direct current passed be
tween said active and stable anode and an in
active cathode without the use of a diaphragm, 15
removing resultant quinone as a solution in ben
zene and supplying more benzene to the cell, and
so adjusting such removal and supply as to keep
the quinone concentration of said solution rela
tively low.
HERBERT PALFREEMAN.
NORMAN VICTOR SYDNEY KNIBBS.
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