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Patented Sept. 10, 1946
Adrian L. Linch, Wilmington, Del., assignor to
E. I. du Pont de Nemours & Company, Wil
mington, Del., a corporation of Delaware
N0 Drawing. Application September 16, 1942,
Serial No. 458,580
4 Claims.’ (01. 260-437)
This invention relates to a process for stabiliz
pounds which, although present in very small
ing or deactivating sludges, precipitates and
amounts, ?nally are deposited as sludges in the
residues occurring or used in the manufacture of
pipes and tanks and other processing equipment
and these sludges which contain tetraethyl lead
tretraalkyl leads, and which normally tend to
promote decomposition and ignition of the tetra
alkyl leads that may be contained therein.
It is known that alkyl metal compounds in
general are quite unstable and decompose readily,
adsorbed therein when exposed to oxygen or air
often ignite, thus presenting serious ignition and
explosion hazards in the process.
Methods have been advanced for the removal of
particularly in the presence of air or oxygen. It
practically all the sludge forming materials from
has also been found that these alkyl metal com 10 the tetraethyl lead after its distillation, such as
pounds are particularly unstable when adsorbed
by controlled blowing with air or oxygen with
on materials which present a large surface area
agitation, preferably under a layer of water, fol
per unit volume such as silica gel, clays, alumina,
lowed by separation of the precipitated sludge. as
earths, asbestos, charcoal, and materials of
more particularly described in copending applica
similar structure which materials appear to exert
tion Ser. No. 393,680. However, even in these
a catalytic e?ect in the decomposition of these
cases the sludges which are deposited by the
alkyl metal compounds. Even tetraalkyl leads
action of the oxidizing agent and which in
such as tetraethyl lead which is known to be
variably contain tetra-ethyl lead, tend to ignite
somewhat more stable than some of the other
when exposed to air thus presenting serious igni
alkyl metal compounds decomposes and often
tion hazards, making it desirable that even these
ignites in the presence of oxygen when small
sludges should be deactivated during their forma
amounts are adsorbed on materials that o?er ex
tion or afterwards to permit of their removal and
tended surface areas, particularly when the
disposal in a safe manner.
masses containing the tetraethyl lead are exposed
It is therefore an object of this invention to
to temperatures somewhat higher than normal
provide a process for stabilizing sludges, pre
atmospheric temperatures.
The tendency to
cipitates and residues occurring in the manufac—
ture of tetraalkyl lead compounds whereby the
ignition hazard presented by the lead alkyl com
oxidize and ignite of course varies with the sub
stance With which the alkyl metal compound is
incorporated, some materials apparently exerting
a greater catalytic e?ect than others in promot
pounds in contact with such catalytic surfaces is
30' reduced or completely overcome.
ing ignition of the alkyl lead compounds.
In the manufacture of tetraalkyl leads, such as
tetraethyl lead, tetramethyl lead and the mixed
ethyl-methyl lead compounds, sludges are formed
It is a still further object of the invention to
render inactive materials which tend to exert a
catalytic effect in the decomposition of tetraalkyl
leads in the presence of air thus permitting the
from which it is difficult and, from a practical -
safe use of such materials as ?lter aids in the
standpoint, impossible to entirely free from the
alkyl lead compounds during the normal steam
manufacture of tetraalkyl lead.
I have found that sludges, precipitates and
distillations or decantation operations. There is,
residues occurring or involved in the production
of tetraalkyl leads which offer large surface areas
divided lead and impurities such as bismuth con - 40 per unit volume and which normally tend to exert
therefore, carried through the process very ?nely
catalytic effect and cause decomposition and
ignition of the tetraallryl lead which may be con
tained therein can be rendered inactive con
(2) An alkyl group substituted by one or
more of the groups, -—OH, —COOH, —COO
veniently and economically by washing or other
(3) A long chain alkyl (more than 8 carbon
wise treating them with solutions or dispersions
atoms) ;
of trivalent organic nitrogen compounds. These
stabilizing or deactivating agents appear to be
preferentially absorbed by the active materials,
which materials retain their capacity to absorb
the tetralkyl lead although they no longer have
the property of inducing ignition of the tetra
alkyl lead absorbed therein.
(or nitrogen substituted derivatives),
By the terms “sludges,” “precipitates” and
“residues” We include those ?lter aids which may
be employed in the production of the tetraalkyl
leads and which offer a large surface area per
in which R3 is an aryl group substituted by
unit volume and are known to accelerate decom
position of the tetraalkyl leads on exposure to air
(6) —-SO2-—R4 in which R4 is an aryl group
or oxygen such as clays, silica, earths, charcoal,
substituted by —NH2 or by an alkyl group
etc. These ?lter aids are rendered. inactive by 20
or Where R4 is a long chain alkyl (more
trating them with trivalent organic nitrogen com
pounds either before or after they are employed in
than 8 carbon atoms) ;
the process.
The effectiveness of the trivalent
R1=I—I, alkyl, aryl, substituted alkyl or substituted
aryl; (R and R1 together may be =C—aryl
organic nitrogen compounds in the deactivation
of these active materials is not materially reduced *
substituted by -—OH) ;
by washing the deactivated materials with water
R2:=H,' alkyl, aryl, substituted alkyl, substituted
aryl or heterocyclic.
The trivalent organic nitrogen deactivators are
The trivalent organic nitrogen compounds that
preferably used as aqueous solutions which con
may be employed for this purpose 'may be 30 tain the deactivating agent in an amount equiva
primary, secondary, or tertiary, aliphatic or
lent to approximately one-third of the dry weight
aromatic amines, or they may be trivalent nitro
of the material to be stabilized. The amount of
gen compounds in which the nitrogen forms part
deactivator employed may, of course, be varied
of a heterocyclic ring. . Those which have been
over a Wide range with equally good results. By
found to be useful vary widely in chemical comemploying the stabilizer in an amount ranging
position and in molecular weight. The only
from 0.05% to more than 100% of the dry weight
limitations upon this class of compounds, insofar
of the active material, satisfactory results have
as I have been able to determine, is that if they
been obtained. The stabilizing e?ect may be ob
are straight alkyl amines or unsubstituted ary1~
tained in some cases by using even smaller
amounts of the deactivating agent, although a
amines they should contain at least seven carbon
atoms in at least one alkyl or aryl group and in
sur?cient amount should always be used to insure
both the aliphatic and aromatic series they should
complete deactivation of the active material.
not contain a free sulfonic acid group. The sul
The use of excessively large quantities over that
fonic acid group as such appears to render these
actually required to deactivate the active mate
or other solvents or by drying them down prior to
active .
sludges and residues although substituted sulfonic
acid groups may be present in the molecule with
out rendering them inoperative as deactivating
agents. Aniline itself, which is the simplest mem
ber of the aromatic series, is very weak in its de
activating power and can be used only with the
less active type of residues or other materials
which tend to exert the catalytic effect in a more
mild degree. The simple substituted anilines such
as para amino phenol, para nitro aniline, etc, s
have been found to deactivate the most active
types of residues. The property of deactivating
active materials of the type mentioned does not
appear to depend upon whether the materials are
soluble or insoluble in water or other solvents
from which they may be applied to these residues.
As illustrative of the types of trivalent nitrogen
compounds that may be employed are those hav
ing the general formula
rials merely contributes unnecessarily to the cost
of the process and serves no useful purpose.
The deactivating agent is preferably employed
in a solution of a concentration of from 1 to 5%
although lower or higher concentrations may be
used. It is, of course, advantageous to employ a
su?lcient amount of solution to insure complete
contact of all the material to be deactivated. To
prevent the use of unnecessary large amounts of
the deactivating agent, it will usually be found
desirable to use a relatively large volume of so
lution of a concentration of less than 5%. Where
there is an advantage of employing a lesser vol
ume of solution, the concentration may, of course,
be increased.
An important use of the present invention in
the commercial manufacture of tetraethyl lead is
to deactivate the sludges which are precipitated
and removed from the crude tetraethyl lead in
the puri?cation step. A method of precipitatting
and removing these sludges by treating the crude
tetraethyl lead with oxidizing agents such as with
air or oxygen is more particularly disclosed in
copending application Ser. No. 393,680. The pre
R—_—(1) An aryl group substituted by one or more
of the following: -—OH, —-COOH, —COO
metal, —NO2, —CHO, ——0 alkyl, --—0 alkyl
OH, —NH2, aryl—NHz, --S—aryl, alkyl
(more than 4 carbon atoms), phthaloyl;
cipitated sludges from this process collect in the
aqueous layer from which the puri?ed tetraethyl
lead is separated by decantation. Although dis
persed in the water layer the sludge retains su?i
cient tetraalkyl lead absorbed therein to ignite on
contact With oxygen or air, particularly at slight“
ly elevated temperatures. In order to permit the
In regular plant application of this method of
sludge deactivation, it may not always be ‘con
venient to run a laboratory analysis in order to
determine the amount of sludge to be expected,
safe handling and disposition of these sludges, it
has been found desirable to deactivate them be
fore they are removed from the system. This can
be done conveniently by adding a quantity of one
of the deactivating agents to the aqueous sludge
dispersion and then agitating the mass to assure
complete contact of all the sludge with the de
activating material, or an aqueous solution of the
deactivating agent may be used to cover the
tetraalkyl lead during the accelerated sludge pre
and such a procedure is not necessary. We have
found that under usual conditions the quantity
of sludge formed per 1,000 parts of tetraethyl
lead seldom exceeds 2 parts, and this ?gure may
be used as a basis for the calculation of the quan
10 tity of deactivator needed. Thus, if we add 0.6
part (30% of the dry sludge weight) of deacti
vating agent to the water layer per 1,000 parts
of tetraethyl lead, sufficient deactivator is pres
cipitation treatment so that the sludge is deac
tivated as fast as it is formed.
The deactivating material may be employed in
an aqueous solution or suspension or in other sol
ent to meet any conditions which we have met.
15 Of course, tetra-ethyl lead manufactured in var
ious plants may vary in sludging capacity de
Where the sludges or precipitates settle out in
pending on quality of raw materials, but in any
the pipe lines or other processing equipment dur
one plant the quantity is relatively constant, and
ing the manufacture or puri?cation of the tetra—
a de?nite amount of deactivator per unit Weight
alkyl leads, they may be deactivated, to insure
safety in their removal or during repair of the 20 of tetraethyl lead may be easily set up as ade
quate in all cases.
equipment, by pumping a solution of one of the
deactivating materials through the apparatus for
Example 2
a su?icient period of time to insure complete con
parts of crude tetraethyl
tact with all the sludge to be deactivated, which
is usually accomplished in from 15 to 30 minutes. 25 lead were placed in a suitable container provided
The?lter aids may be washed with a solution
of the deactivating agent prior to their use in
the process. They may be employed either before
or after drying, for it has been found that they do
not again become active even after being dried. 30
or by being washed by the solutions that are ?l
with means for agitating its contents. About 200
parts of water were added, and the sludge was
precipitated and collected in the water layer as
disclosed in the previously mentioned application
No. 393,680.
After the precipitation treatment was com
plete, ?ve parts of para-phenylene diamine were
added, and the contents of the container 'were
agitated for about 15 minutes. The tetraethyl
storage of crude tetraalkyl lead before it is de
sludged by accelerated sludge precipitation. An 35 lead and the aqueous layer were then ?ltered
together, and the clear tetraethyl lead was de
aqueous solution of one of the deactivators dis
canted from the water layer after ?ltration was
closed may be used to cover the crude tetraalkyl
tered therethrough.
' A further use of the invention is found in the
complete. A sample of the sludge retained on
lead. Any sludge which precipitates at the sur
the ?lter was tested for ignition activity as pre
face of the lead alkyl on standing is stabilized by
contact with the aqueous layer. If desired, all of 40 viously described, and was found to be inactive.
Sludge obtained using the same crude tetraethyl
the precipitated sludge may be brought into the
lead and the same process, except that no para
aqueous layer by suitable agitation since the
phenylene diamine was added. ignited the tetra
ethyl lead which it retained when placed on the
45 steam bath.
activated as soon as it is formed.
It is, of course, understood that other trivalent
The following examples are given to illustrate
stabilized sludge particles readily disperse in the
water layer. In this way the sludge may be de
organic nitrogen compounds may be employed
in this example in place of the para-phenylene
the invention. The parts used are by weight.
Example 1
diamine. The quantities and concentrations em
50 ployed in this example are not to be construed
as limits to the invention, for they may be varied
widely without altering the results obtained.
While in the preceding examples We have used
Approximately 10,000 parts of crude tetraethyl
lead were processed’ in a washer to precipitate
the sludge-forming impurities by the method
‘ stabilizing agents which are soluble in neutral
described in the co-pending application, Ser. No. .
393.680. The precipitated sludge, which by lab
aqueous solutions, deactivating agents that are
oratory analysis of a small sample had been cal
culated to weigh 12 parts, was collected in 1,000
parts of water. The puri?ed tetraethyl lead was
then decanted from the water layer. Approxi
mately 10 parts of p-amino phenol were added
to the aqueous phase producing a solution of
about 1% p-amino phenol. The mixture was
agitated for 15 minutes and ?ltered.
A small portion of the ?lter cake was then
tested for ignition activity by placing it on a'
?lter paper, wetting the cake with a small quan
tity of tetraethyl lead and heating on a steam
bath. No signs of ignition or of charring of the
insoluble in neutral aqueous solutions may be
effectively applied from suitable solutions, such
as dilute sodium hydroxide, or from organic sol
We have found that dispersions, suspen
sions or solutions of the deactivating agent in
solvents other than water may be effectively used.
Where water is used as the solvent or dispersing
medium, the method of applying the deactivator
- vents.
to precipitated tetraalkyl lead sludges is effective
when applied as set forth in Examples 1 or 2.
However, when solvents other than water are
used, the aqueous layer containing the sludge
may be ?ltered off, and the ?lter cake then agi
tated with the solution containing the deactivat
ing agent for a period of from 15 to 30 minutes
?lter paper were noted even after 24 hours on
the steam bath.
A sample of the same sludge which was taken
in a suitable receptacle, or the solvent solution
before the p-amino phenol was added to the
water layer was tested for activity as outlined
above. Ignition occurred shortly after the initial .
' sample was placed on the steam bath.
may be added directly to the aqueous sludge sus
pension. Results obtained on agitating 10 parts
of an active sludge with 50 parts of a solution of
representative trivalent organic nitrogen com
salicylal sorbityl amine were then added to the
water layer, and the sludge was precipitated ‘and
pounds in various solvents are listed in the table
Steam bath stability
tration -
After 21 hrs.
No decomposi-
No_ decomposi-
Per cent
Para phenylene diamine ___________________ _‘. _____________ ..
After 72 hrs.
Water _____ ..
Ortho phenylene diamine _________________________________ . _
Guanyl guanidine sulfate ___________ __
1, 4 di (para tuloido) anthraquinona-
Anthranilic acid ___________________ _.
Para amino phenol ___________________ __
Salicylal sorbityl amine ______________ __
Di (betaehydroxyethyl) aniline ______ ,.
50% ethanol_
Meta-amino benzaldehyde _____ ..' ____ ._
Dimethyl cetylamine _____________ __,__
Para dodecylaniline. _
Stearylamine. _ i _ _ _
Meta nitro aniline. ._
____________ _ _
_ _ _ _ _ _ _ _ . _
_______________________ ._
Salioylal propylene d1am1nc condensation product
2-hydroxy-3-naphthanilide ______________________ __
Suliapyridinc ___________________________ ____
N-di-n-butyl para amyl benzene sulfonan11de_
N-isobutyl para amyl benzene sulfonamidm ._
1, 4~di(p-tolylamino)_anthraquinone ____ _ _
Methyl glucamine _________________ _ .
3 (4 hydroxyphenyl) amino carbazo1e_
Para amino phenyl acetic acid _____ ._
Para phenetidine ________________ __
Para (hydroxy ethoxy aniline ______ __
Dodecyl sulfonyl mono ethanol amide
lndole _____________________ _ _
N o deactivator (control) ___________ -_
removed from the tetraethyl lead by the method
disclosed in the co-pendingv application Ser. No.
393,680. After this operation was complete, the
tetraethyl lead was removed by decantation, and
the aqueous layer containing the sludge was
?ltered. A portion‘ of the ?lter cake was then
As previously stated the invention may be em
ployed to stabilize active ?lter aids which are to
be used in tetraalkyllead ?ltration. These ma
terials may be washed in a solution of one of
the deactivators and rendered suitable for tetra
alky] lead.
well as a
placed on
?ltration. The following ?lter aids as
number of other materials of similar
were wet with tetraethyl lead and
tested on the steam bath as described in Ex
ample 1.
a steam bath as described in Example
No decomposition or ignition of the
tetraethyl lead was noted.
1 above. All were found to initiate the ignition
Example 4
of tetraethyl lead. Ten parts of each of these 40
As previously stated, sludges found in tetra
materials were then agitated for several hours
ethyl lead are also found in other lead alkyls
with 50 parts of the solution of various trivalent
which are manufactured from commercial lead.
organic nitrogen compounds of the concentra
An example of these alkyls are the mixed tetra
tions given in Table 2. Where no solvent is speci
methyl-ethyl compounds of lead, formed when a
?ed, water is used. After the agitation period, I
mixture of methyl chloride and ethyl chloride
the solutions were ?ltered and portions of the
are reacted with lead sodium alloy. All examples
?lter cakes were wet with tetraethyl lead and
in which tetraethyl lead is speci?ed are equally
placed on a steam bath. Results of the tests are
workable with these mixed lead alkyls.
given below:
‘Nash solution
Steam bath testv
Approximately 8,000 parts of crude mixed
tetramethyl-ethyl lead compounds (tetramethyl
lead, trimethyl ethyl lead, dimethyl diethyl lead,
methyl triethyl lead and tetraethyl lead) were
placed in a suitable tank or washer, and 2,000
parts of water containing 20 parts of sodium hy
1% p-phenetidinc in No decomposition.
droxide and 20 parts of 3 (4-hydroxy phenyl)
Yellow lead oxide (N. F.
amino carbazole were added. The contents of
the tank were aerated and agitated for two hours
2% M-nitro aniline No decomposition.
in ethanol.
as disclosed in the copending application Ser. No.
Bismuth subnitrate. _ _-_
393,680. Aftera settling period of a few min
5% anthranilic acid No decomposition.
in 50% ethanol.
60 utes, the clear mixed lead alkyls were decanted
Bismuth oxide (from
from the aqueous layer and the aqueous mixture
hydrolysis ofBi(NO3)2).
5% _rnethyl gluca» No decomposition.
was ?ltered. A portion of the ?lter cake was
tested on the steam bath as described in Example
Ferric oxide (anh) __ _ __.
1% salicylal scrhityl No decomposition.
1, except that the ?lter cake (sludge) was wet
65 with mixed lead a kyl compounds rather than
2% dimcthyl cctyla No decomposition.
with tetraethyl lead. No decomposition or igni
mine in ethanol.
tion of the lead alkyls was noted. ‘A similar ex
Decolorizing charcoaL _ _
5% guanyl guani No decomposition.
periment Was carried out in which no stabilizing
dine sulfate.
Filter aid (clay) _______ __
None _____________ _ _
5% p-amino phenoL No decomposition.
Tone _____________ __
None _____________ _.
Do ________________ _ _
None _____________ __
Do ________________ - .
None _____________ __
Do ________________ __
None _____________ _ .
Do ________________ . _
Activated Al1unina_ _ _ __
None _____________ .i
Do-. _________________ ._
None _____________ _.
Do ________________ ._
agent was placed in the water layer. This sludge
ignited the mixed alkyls when the steam bath
Example’ 3
stability test was made.
Approximately 1,000 parts of crude tetraethyl
lead were placed in a suitable tank or washer,
In testing the activity of the sludges before or
after treatment with the deactivating agents, it
and an approximately equal weight of waterwas
will be noted that tetraethyl or other alkyl lead
added to the tetraethyl lead.
Some 8 parts of 75 was added to the residues. This was to make sure
there was su?icient tetraalkyl lead present to
ing such sludges with p-amino phenol in an
aqueous carrying medium in an amount suf?cient
ignite under the conditions employed, if the
to provide at least 0.05% of the p-amino phenol
sludge was not fully inactivated, for in some in
based on the dry weight of the sludges.
stances, it is possible that the amount of alkyl
2. The process for inhibiting the spontaneous
lead may be reduced to such a small amount that
ignition of tetraethyl lead adsorbed on sludges
ignition might not be noted. While the elimina
which are precipitated from crude tetraethyl lead
tion of the alkyl lead from the residues to such
and which sludges normally tend to cause spon
an extent does not ordinarily take place,~ the
taneous ignition of the tetraethyl lead adsorbed
tests were made under conditions favoring igni
thereon when exposed to oxygen, which com
tion provided the sludge or ?lter aid was active.
prises washing such sludges with p-amino phenol
This invention makes possible the deactivation
in an aqueous carrying medium in an amount
of the ignitable sludges and residues occurring
su?icient to provide at least 0.05 % of the p-amino
in the manufacture of tetraalkyl lead compounds
phenol based on the dry weight of the sludges.
and is of particular value in eliminating fire and
3. The process for inhibiting the spontaneous
explosion hazards involved in the removal and 15
ignition of tetraethyl‘lead adsorbed on sludges
disposal of such sludges from the process and in
which are precipitated from crude tetraethyl lead
overcoming the potential ?re hazard arising from
and which sludges normally tend to cause spon
the collection of such sludges and precipitates
taneous ignition of the tetraethyl lead adsorbed
which accumulate in various places in the proc
essing equipment and which when exposed to air 20 thereon when exposed to oxygen, which comprises
washing such sludges with m-nitro aniline in an
often ignite with considerable damage. The in
aqueous carrying medium in an amount su?icient
vention also permits the use of ?lter aids which,
to provide at least 0.05% of the m-nitro aniline
unless rendered inactive, tend to cause ignition
based on the dry weight of the sludges.
of any absorbed tetraethyl lead when they are
4. The process for inhibiting the spontaneous
exposed to the air. Any other absorbent mate 25
ignition of tetraalkyl lead compounds adsorbed
rials which for any reason may become saturated
on sludges which are precipitated from crude
with tetraethyl lead in or about the plant in
tetraalkyl lead compounds and which sludges
which it is being manufactured may be rendered
normally tend to cause spontaneous ignition of
inactive by washing or otherwise treating with
the tetraalkyl lead compounds adsorbed thereon
stabilizers of the type described so that poten
when exposed to oxygen, which comprises wash
tial ?re hazards may be removed as far as pos
ing such sludges with an aromatic amine in an
sible. Lagging on pipe which due to leaks may
aqueous medium such aromatic amine being a
become saturated with tetraethyl lead and which
member of the group consisting of p-aminophe
have been known to cause its ignition can be
nol, m-nitro aniline, para nitro aniline, para
inactivated by treating such lagging with the de
activating agents.
I claim:
1. The process for inhibiting the spontaneous
ignition of tetraalkyl lead compounds adsorbed
phenylene diamine, ortho phenylene diamine, 1,4
di(para toluido) anthraquinone, anthranilic acid,
di(beta - hydroxyethyl)
meta - amino
benzaldehyde, para dodecylaniline, 1,4-di(p—tol
on sludges which are precipitated from crude 40 ylamino) -anthraquinone, para amino phenyl ace
tetraalkyl lead compounds and which sludges
normally tend to cause spontaneous ignition of
the tetraalkyl lead compounds adsorbed thereon
when exposed to oxygen, which comprises wash
tic acid, para phenetidine and para(hydroxy eth
oxy) aniline.
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