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Патент USA US2411832

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Patented N09. 26, ‘1946
Hooper Linford, Manhattan Beach, and William
J. Baral, Long Beach, Calif., assignors to Union
' Oil Company of California, Los Angeles, Calif.,
a corporation of California
No Drawing. Application July 2'7, 1942
Serial No. 452,418
7 Claims.
metals and organic acids.
The term “salts” is sometimes used to describe
process for preparation of soaps which are rela
tively water-insoluble from soaps which are rela
some of the metal-organic compounds which we
refer to as “soaps,” but we prefer to use the term
tively water-soluble, by metathesis; a preferred
embodiment being improvements in the process
“soaps” in this application to avoid ‘confusion
with the inorganic “salts” suchas copper sulfate
of metathesizing sodium naphthenate and copper
sulfate to form the water-insoluble copper naph
The uses of such soaps are many and varied.
Copper naphthenate is at present in great de
mand for treatment of burlap sacks to retard
rotting. Other water-insoluble 'soaps to which
our invention is applicable have been employed
as components of inks, paints, driers, fungicides,
adhesives, dyes, pigments, lubricants, fuels, oint
and sodium chloride, etc., which are also in
volved in the reactions. As a second item of
nomenclature, the terms “soluble” and “insol
uble” as used in this speci?cation, except when
quali?ed, shall be construed to mean “water-sol
uble” or “water-insoluble,” respectively. Similar- ‘
1y, by “naphthenic acids” is meant the usual mix
15 ture which may contain some acids of other types
such as the acyclic arachidie acids for example.
In the past, the commonly used method of
ments, etc.
Metathesis, or double decomposition, is a com
mon type of chemical reaction which may be illus
trated by the following equation:
tion is applicable to the soaps of many other
This invention relates to improvements in the
preparing a water-insoluble soap such as copper
naphthenate by metathesis, has involved mixing
20 equivalent proportions of water solutions of so
dium naphthenate and copper sulfate, with added
naphtha as a gathering agent for the water-in»
In applying this general equation to the speci?c
soluble soap, agitating until the reaction is com
example of the preceding paragraph, AX would
plete, settling, drawing off the water layer, wash
represent the' sodium naphthenate, BY the cop
per sulfate, AY the sodium sulfate, and BX the 25 ing the oil-copper naphthenate layer with wa
ter, ?ltering, and if desired, removing the added
copper naphthenate. The driving force of the
naphtha by distillation.
reaction may be considered to be the insolubility
The above process has several features which
of one of the reaction products (in this example
are decidedly, objectionable froma commercial
the copper naphthenate), and the completeness
of the reaction will depend on the relative degree 30 standpoint. One of the worst of these is the
tendency of the reaction mixture and the water
of insolubility of one of the products (or its .ef
washing mixtures to form emulsions which are
fective removal from the system) as compared
extremelyslow in breaking. This makes the en
with that of the reactants. The invention is ap
tire process a very slow one, increases costs, and
plicable, therefore, to the preparation of any soap
which may be formed bythe above type of re- : so Ll tends to cause high material losses. There is
also a distinct ?re hazard involved where, naph
action, i. e., to the formation of a water-insoluble
tha is present in the open kettlesnormally em
soap from the corresponding water-soluble soap
and a relatively water-soluble salt of the desired
ployed in the metathesis step;
, It is theprincipal object of this invention to
metal. The organic acid constituent of the soaps
involved is preferably a relatively strong organic ll) provide improvements. in the above process of
preparing insoluble soaps which eliminate many
acid having a dissociation constant greater than
of its‘ defects." These improvements canbe more
about 10-”, as for example a fatty acid, naph
thenic acids extracted from petroleum, a prod
uct of oxidation’ of petroleum fractions, a sul
fonic acid derived by sulfuric acid treatment of
_ petroleum fractions, or any other similar organic ‘
‘clearly understood after considering‘the follow
ing description of the complete improved proc
ess, which for convenience is outlined as a series
of steps and is exempli?ed by a description of
copper napthenate, this being a preferred form
‘acid; however, it may be a relatively weak acid
of the invention.
such as the "phenols” extracted from petroleum,
an alcohol, mercaptan, imide, etc., in some in
Step 1.—-Preparation of the water soluble ‘soap
stances. The metals most commonly forming 50 '
water-insoluble soaps are the polyvalent metals
Kerosene and gas oil fractions from a Califor
such as copper, lead, tin, aluminum, iron, zinc,
barium, chromium, etc., although monovalent _
nia crude oil were each extracted with aqueous
caustic soda solution originally containingabout
metals such as silver may also be included. These
mentioned are merely examples, and the inven 55 6 lbs. NaOH per bbl.,, until the bulk of the caustic
in each case was converted to sodium naphthenate
(3) No water washing is used. It has been
by the naphthenic acids present in the oil frac
tions and the resulting solution had a basicity to
phenolphthalein equivalent to an NaOH content
of about 0.5 lb. per bbl. These “crude soaps”
cluding the water soluble salts by dehydrating
found that removal of inorganic impurities in
and settling is fully as effective and much more
rapid than the usual water washing, and also
results in a product soap completely free from
were then blended, and the blend Was acidi?ed
with sulfuric acid to obtain a supernatant layer of
"crude acids” having an acid number of about 150
mg. KOH per gram.
water, and‘therefore having improved oil solu
bility characteristics.
The “crude acids” were then" ' ' '
separated and distilled, taking a “heart out” com
prising about a 5% to 80% overhead fraction, this
material being designated “distilled crude acids”
and. having an acid number of about 1'75 mg. KOH
per gram. A charge of about 30 tons (175 bbls.) of
these “distilled crude acids” was then introduced
into an “agitator” equipped for heating, cooling,
and agitation, and the calculated equivalent
amount of caustic, namely about 92 tons (500
' The invention therefore resides in the produc
tion and separation of the Water-insoluble soap
phase by‘ the addition of solid salt to the reaction
' mixture in the absence of any added oil or naph
tha as a gathering agent; in the puri?cation of
the Water-insoluble soap phase by heating to
drive off volatile impurities and adding a solvent
to facilitate settling or ?ltration to remove solid
' impurities; in the combination of these steps;
and in an improvement designed to facilitate the
bbls.) of an aqueous caustic soda solution con
separation of the water-insoluble soap phase
taining 15 lbs. of NaOH per bbl. was added. The 20 from the aqueous phase described below.
mixture was heated to a temperature between
The invention has been illustrated by the met
150° F. and 175° F. and agitated for about 21/2
hours to complete the saponi?cation, and‘ the pH
of the resulting solution was adjusted to 8.0 by
addition of a small quantity of caustic (naph- -‘
thenic acids may be required in some instances).
Step 2.-—Formation of the insoluble soap- by met
To the above prepared aqueous sodium naph- ;
thenate solution was added slowly with agitation
the metathetical equivalent weight, 11.7 tons, of
solid copper sulfate (CuSO4.5I-I2O) in the form of
small granules. The mixture was again agitated
hot for about 2 hours, and allowed to settle. The
aqueous phase was then withdrawn from the su
pernatant liquid copper naphthenate soap layer.
Step 3.--Puri?cation of the insoluble soap
The above copper naphthenate soap phase,
which carried with it small amounts of water
and other impurities such as water-soluble salts,
was charged to a shell still, in which it was heat
vedjust suf?ciently to boil off all of the water.
This also effectively precipitated the water-solu
ble salts. About 200 bbls. of mineral spirits, was
then added and the charge was mixed, and set
tled until clear. The clear solution of copper
naphthenate in mineral spirits, which was the
desired. product in this example, was decanted,
leaving in the still a small residue of copper
naphthenate solution plus the settled solid impur
ities. The still was then flushed with mineral
spirits (which was drawn off into an auxiliary
tank, allowed to settle, and used as the diluent
for the next batch of copper naphthenate), and
?nally ?ushed ‘with water and steam.
It may be observed that the above'process dif
'fers_ from
the conventional
ing particulars:
process in the follow
v (l) The precipitating salt employed in the
metathesis‘is used in the form of a solid instead
‘of an aqueous solution. This eliminates the step
athesis‘ of sodium naphthenate and copper sulfate
to produce copper naphthenate. However, the
inventionis applicable to the preparation of a
very large variety of soaps as indicated above.
The following description is intended to show the
reasons for some of the operating conditions used
in the above preparation of copper naphthenate,
and to clarify the operating conditions which
may be used in other preparations.
In the extraction of petroleum fractions with
caustic soda to form the “crude soaps” as in Step
1 above, it is desirable to employ a solution of
such strength as to minimize emulsi?cation of
the two phases‘ which may otherwise result in loss
of sodium naphthenate to the oil and in excessive
entrainment of oil in the “crude soaps.” Some
entrainment always occurs, however, as evidenced
by the fact that the “crude acids” cracked out
from the “crude soaps” as described above, may
contain about 25% or 30% of “unsaponi?ables”
such as entrained oil and unstable asphaltic or
resinous materials.
The “crude acids” or “crudesoaps” may be
used in place of the “distilled crude acids” or the
soaps made therefrom in our process, particularly
when the petroleum fractions being extracted are
“clean” distillates of relatively lowv molecular
weight, such as kerosene, stove oil, etc., and the
percent of unsaponi?ables is relatively low, self
below about 20%.
It is preferable, however, es
pecially where cracked, residual, ‘or. high molecu
lar weight stocks are extracted, to use the “dis
tilled crude acids” as described above, since these
are free from, high molecular weight materials,
unstable materials, etc., which might cause exces
sive emulsi?cation in the succeeding metathesis.
The “distilled crude acids” described usually
vcontain about 15% to 20% of dissolved entrained
,oil of‘ moderate molecular weight (kerosene to
gas oil). This is not a necessary part of the in
vention however, since as described below, our
process is also applicable to highly re?nednaph
of dissolving the salt, and reduces the volume of
thenic acids, which contain 3% or less of .un
the reaction mixture.
65 'saponi?ables, as well as to organic acids other
(2) No naphtha is added to the reaction mix
than naphthenic acids, which may containno
ture. This practically eliminates ?re hazards in
oil. It has been found, moreover, that the pres
this step. Furthermore, the absence of added
ence of such normally entrained oil of moderate
naphtha and the reduced volume of aqueous solu
molecular weight (a portion of thefstock being
tion as noted above result in the formation of an 70 extracted) is, ‘not analogous to the presence. ofa
aqueous phase consisting of a moderately concen
similar or larger amount of naphtha used as a
trated salt solution and a supernatant phase con
gathering agent in conventional processes, in that
sisting of nearly pure insoluble soap. These two
it does not result in objectionable emulsifying
concentrated phases occupy a relatively small vol
tendencies. For example, a highly re?ned sam
ume, and have very little tendency to emulsify. 75 vple of naphthenic acids of the above type con‘
The most common bases employed for forma
taining only about 3% of unsaponi?ables was
tion of the soluble soaps are those of the alkali
metals, especially sodium and potassium, and '
ammonia. Ammonia, of course, can not be used
for the preparation of copper soaps, or the soaps
of any other metal which forms a stable am
used in two series of similar experiments in which
copper naphthenate was formed and separated
as in Steps 1 and 2 above, except that the experi
ments were conducted on a smaller scale.
each series of experiments, oil was added to the
monium complex which prevents the added salt
acids in amounts of 15%, 30%, 100% and 200%
from entering into the metathesis reaction.
by weight‘, respectively. In ‘one series the »oil
In the metathesis, Step 2 above, the water-in
was" a portion of the parent gas oil-kerosenefrac
soap phase may be either the upper or
tion from which the acids were originally ex
the lower layer after stratification. In the above
tracted; while in the other series the oil was
copper naphthenate example, it was the upper
a naphtha (mineral spirits). The degree of
layer, while in a similar preparation of lead naph
emulsi?cation experienced in the metathesis step
it was the lower layer. Obviously, there
in each experiment was measured by the vol
ume of emulsion “cuff” remaining after 2 hours 15 will be other preparations or variations in oper
ating conditions which will result in approxi
of settling, expressed as a percent of the volume
mately equal speci?c gravities for both the in
of the clear supernatant copper naphthenatc soap
soluble soap phase and the aqueous phase, thus
phase. The results follow:
making the rate of Strati?cation extremely slow.
20. In this event the speci?c gravity of one of the
Resulting per cent emulsion
phases must be modi?ed.
based on clear soap phase
The speci?c gravity of the aqueous phase may
be modi?ed by a change in the concentration of
Weight per cent oil added
based on acid content
In presence Infprgsfrace
the base used to saponify the organic acid in the
of added
' preparation of the soluble soap. For example, the
parent oil
____________ ._
re?ned naphthenic acids containing about 3%
0f unsaponi?ables described above were saponi
?ed as in Step 1 above by reaction with caustic
of about 15 lbs. NaOH per bbl. strength (1 M)
30 in one experiment, and with caustic of about 3
lbs. Na'OI-I‘per bbl. strength (0.2 M) in a second
These data show clearly one of ‘the advantages
of operating without added naphtha, as well as ,
experiment. In the subsequent metathesis as in
Step 2 above, the insoluble soap phase strati?ed
above the aqueous phase in the ?rst experiment,
the difference between the low boiling oilsadded
in conventional processes, and the parent oil 35 and below the aqueous phase in the second ex
normally present in extracted naphthenic acids,
when each is present in relatively small quan
tities. When naphtha is employed as a gather
ing agent in the conventional processes, inciden
tally, it is common practice to add 100% by
weight or more on the above basis.
Similar. modi?cation of the speci?c
gravity of the aqueous phase could be accom
plished by adding either water or a water soluble
salt or heavy brine to the reaction mixture during
Step 2,
The speci?c gravity of the insolublesoap phase
may also be ‘modi?ed’ to avoid equal speci?c grav
The strength of the caustic soda or other base
ities of the two phases. The addition of naph
used to form the aqueous solution of the water
tha as in conventional processes tends to reduce
soluble soap- is limited by the following‘ consider
the speci?c gravity of this soap phase, but it may
ations. It should be strong enough to keep the
have the disadvantage of increasing emulsi?ca
volume of the solution at a reasonably low value,
tion tendencies as noted above. The addition of
and to minimize emulsion tendencies; yet it
small amounts of parent oil‘ would be preferable,
should not be so strong as to interfere seriously
in preparing naphthenate soaps.
with the freedom of contact between the water
soluble soap and the added salt, either by “salt 50' We have found a means of modifying the spe
ci?c gravity of the insoluble soap phase. how
ing on ” the water-soluble soap or by imparting
ever. which is believed to be novel, and which has
excessive viscosity or emulsi?ability to the solu
an additional bene?cial effect in reducing emulsi
tion. Bases having strengths of about 0.2 M to
?cation tendencies, which effect may be due to
2.0 M (mols per liter) have been found generally
In the neutralization of naphthenic acids,
using caustic soda as above, it is desirable to
stop at an end point pH of about 8.0. This is
modi?cation of the existing interfacial tension.
The addition of carbon tetrachloride to the re
action mixture in amounts as low as a few per
cent or possibly as high as 100% of the volume of
the aqueous phase will cause the insoluble soap
done to insure minimum acid loss with maximum
utilization of caustic, and to eliminate complica 60 phase to stratify below the aqueous phase in in
stances where the two phases normally have ap
tions resulting from precipitation of- insoluble
proximately equal speci?c gravities, and will also .
metal oxides or hydroxides. Similar considera
decrease tendencies toward emulsi?
tions will dictate the pH to be used as an end
cation. The carbon tetrachloride will then ac
point in other preparations. For example, in
neutralizing weaker acids such as the petroleum 65 company the insoluble soap to the subsequent
puri?cation as in Step 3 above, where it may be
phenols, it may be desirable to stop at a much
distilled off with the entrained water and reused,
higher pH, e. g, 10 or higher. If too high a pH
etiher after separation'from the distillate water
is employed, however, there may be a side reac
layer, or in conjunction with that layer. Other
tion involving considerable precipitation of an
vinsoluble metal hydroxide during the metathesis 70 solvents which are suitable for this purpose are
those organic liquids which are stable, non-reac
step when certain metal salts are added, and
tive, water-insoluble, and miscible with the wa
this could cause contamination of the water-in
ter-insoluble soap under the conditions of use,
soluble soap phase with free organic acids, or
even prevent appreciable metathesis of the water
insoluble soap.
and which have speci?c gravities above about
75 1.2, and boiling points between about 150° F. and
300° F, These include allyl iodide, trichlorethane,
butyl bromide, etc.
phase and an insoluble soap phase, separating
said phases and then separating water and solid
inorganic impurities from said insoluble soap
It is obvious from the above disclosure that the
occurrence of equal speci?c gravities of aqueous
and insoluble soap phases may be avoided by
2. A process according to claim 1 in which the.
any suitable combination of the methods de
organic acid has a dissociation constant greater
scribed. It should also be noted in this connec
than about 10"’.
tion that the temperature of the stratifying mix
- ,3. A process for preparing a relatively water
ture may play an important part in the relative
insoluble metal soap of naphthenic acids which
speci?c gravities of the two phases, since it has 10 will also form» a relatively water soluble soap of
been observed that the co-e?icient of expansion
a second metal, which consists in adding a solid
of the insoluble soap phase is frequently much
granular salt of said ?rst metal, with agitation,
greater than that of theaqueous phase. In fact,
to a water solution of a naphthenate of said secmixtures have‘ been prepared in which the in
ond metal so as to form the naphthenate of said
soluble soap phase will stratify above the aqueous 15 ?rst metal by metathesis, allowing the reaction
phase while hot, yet will sink below the aqueous
mixture to separate into an aqueous phase and
phase when cold.
an insoluble soap phase, separating said phases,
It is not necessary in all cases to conduct the
heating said insoluble soap phase to effect sub
metathesis at elevated temperatures, but it gen
stantial dehydration thereof and then separat
erally shortens the reaction time, and may re
ing solid inorganic impurities from the dehydrat
duce emulsion troubles. It may be necessary,
ed product.
moreover, in some cases, to operate above the
4. A process according to claim 3 in which a
melting point ofv one of the constituents. For
volatile hydrocarbon diluent is added to the in
example, the ?nal step in purifying the water
soluble soap phase after its separation from the
insoluble soap, involving separation of solid im 25 aqueous phase to facilitate the separation of the
purities by settling or ?ltration, obviously re
quires liquid phase operation, and this may re
5. A process according to claim 3 in which the
quire elevated temperatures when the desired
separation of the reaction mixture into an aque
soap is normally a'solid, and no diluent is pres
ous phase and an insoluble soap phase is effected
30 in the presence of a water insoluble, halogenated
The addition of mineral spirits to the dehy
organic liquid boiling between about 150° F. and
drated. soap as shown in the example is not a vital
about 300° F. and having a speci?c gravity great
part of the invention, but in case the water-in
er- than about 1.2 whereby said insoluble soap
soluble soap is desired in the form of a solution
phase is dissolved in said halogenated liquid and
in mineral spirits or other diluent, it may be of 35 the solution separates as a lower layer.
some advantage to add said diluent to the water
6. A process according to claim 3 in which the
insoluble soap phase ‘ (after separation of the
separation of the reaction mixture into an aque
aqueous phase), so as toexpedite the settling or
ous phase and an insoluble soap phase is effect
?ltering of the precipitated salts from the dehy
ed in the presence of carbon tetrachloride where
drated soap. It may be of some further advan 40 by said insoluble soap phase is dissolved in said
tage to add the diluent before dehydrating, thus
carbon tetrachloride and the solution separates
providing mixing by convection. ' Also, if desired
as a lower layer.
in the latter operation. a portion of a suitable
7. A process for preparing copper naphthenate
diluent may be taken overhead with the water in
which consists in reacting an aqueous solution
the dehydration, thus permitting a lower tem
of- sodium naphthenate with a solid granular
perature for the dehydration.
copper salt at a temperature between about 100°
It is obvious that many minor modi?cations in
and the initial boiling point of the reaction
speci?c procedures other than those mentioned
mixture,‘ with agitation, so as to form copper
may also be applied without exceedingr the scope
naphthenate by metathesis, allowing the reac
of the invention de?ned by the following claims. 50 tion mixture to separate into an aqueous phase
We claim:
and a copper naphthenate soap phase, separat
1. A. process for preparing a relatively water
ing said phases, heating said copper naphthenate
insoluble metal soap of an organic acid which is
phase to effect substantial dehydration thereof,
also capable of forming a relatively water soluble
adding a volatile hydrocarbon diluent to said de
soap of a second metal, which consists in adding
hydrated soap phase, separating solid inorganic
a solid granular salt of said ?rst metal, with agi
impurities from said diluted phase, and separat
tation, to a water solution of a water soluble soap
ing said volatile hydrocarbon diluent from the
of said acid and said second metal so as to form
said relatively water insoluble soap of said acid
and said ?rst metal by metathesis, allowing the 60
reaction mixture to separate into an aqueous
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