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Патент USA US3032506

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nited States atent
Patented May 1, 1962
The l-carboxy-l-hydroxy aliphatic phosphonic acids
are prepared from the corresponding alpha-ketoaliphatic
carboxylic acids by reacting these either with phosphorus
John E. Milks, Stamford, Vernon P. Wystrach, Noroton
Heights, and Frederick H. Siegele, Westport, Conn., as
signors to American Cyauamid Company, New York,
trichloride or with phosphorous acid or a Water-soluble
salt thereof, such as an alkali metal salt. The novel se
questrants are obtained by reacting together equimolecu~
lar quantities of the alpha-ketoaliphatic carboxylic acid
N .Y., a corporation of Maine
No Drawing. Filed Dec. 31, 1959, Ser. No. 863,063
9 Claims. (Cl. 252—8.55)
and the phosphorus compound, but preferably a slight ex
cess, such as a S%—15% excess, over the theoretical quan
This invention relates to methods for sequestering or 10 tity of phosphorus compound is employed.
inhibiting the precipitation of metal ions from aqueous
When PCls is used it is condensed with the ketoaliphatic
solutions containing same and has for its principal object
acid by simple admixture, preferably with cooling, to
the provision of a novel class of sequestering agents for
avoid temperatures above 35° C. The condensation takes
this purpose. A further object is the provision of novel
place with evolution of gaseous hydrochloric acid and
sequestering agents that are particularly eifective within
may advantageously be carried out in the presence of an
the pH range of about 6 to about 11. A further particu
acidic diluent, such as acetic acid, if desired. When the
lar object is the provision of iron sequestering agents that
condensation is complete the mixture is poured into water
are particularly effective within the pH range wherein
and hydrolyzed to form the desired l-carboxy-l-hydroxy
ferric hydroxide is strongly precipitated; i.e., from a pH
alkylphosphonic acid which may be recovered by evapo
of about 6 to about 11. A still further particular object 20 rating the solution to dryness.
is the provision of subterranean ?ooding processes where
The sequestrants are likewise obtainable by reacting
in the novel sequestrants are employed to prevent plug
'alpha-ketoaliphatic carboxylic acids or their esters with
ging of the subterranean channels and pores by iron de
phosphorous acid. They are also obtainable by reacting
posits, and the like. Still further objects will become apthe alpha-ketoaliphatic carboxylic acids with alkali metal
parent from the following description of the invention 25 phosphites, such as Na2HPO3, whereupon the correspond
when taken with the appended claims. '
, r
ing alkali metal salts of the l-carboxy-l-hydroxy aliphatic
It has been found that the l-carboxy-l-hydroxy ali
phosphonic acids are obtained directly. It will be un
phatic phosphonic acids and their water-soluble ‘salts are
derstood that these alkali metal salts, as well as other
good sequestrants in acidic, neutral and alkaline'aqueous
water-soluble salts, may be added directly to aqueous
solutions; when added to such solutions they prevent the 30 metal-ion-containing media as combined nuetralizing and
precipitation, for example, of iron as ferric or ferrous
sequestering agents.
hydroxide, probably by forming complexes. They ex
Representative sequestrants that can be prepared by
hibit their highest sequestering ef?ciency for iron in the
these methods and used in practicing the process of the
pH range from about 6 to about 11; that is to say, a given
invention are, in addition to those mentioned above, 1
concentration of the phosphonic acid compounds will 35 carboxy-l-hydroxypropylphosphonic acid, l-carboxy-l
sequester and prevent the precipitation of a larger quan
tity of iron in this range than under more strongly acid
conditions. The importance of this fact is, of course,
that iron hydroxide formation and deposition are usually
hydroxybutylphosphonic acid, l-carboxy-l-hydroxyiso
butylphosphonic acid, l-carboxy-l-hydroxycaprylphos
most troublesome under neutral or alkaline conditions; 40
droxyethenylphosphonic acid, l-carboxy~1-hydroxy-2-pro
therefore, the new sequestrants are most efficient in the.
particular range where they are most needed;
penylphosphonic acid, and their sodium, potassium and
The phosphonic acids used in practicing the invention
are described accurately by the formula
The process of the present invention is practiced sim
HO/ 1‘.
in which R is the residue of an alpha-ketocarboxylic acid
and is therefore hydrogen or any suitable hydrocarbon
radical. The most common alpha-ketocarboxylic acids
are those of the fatty acid series, in which R is hydrogen
or a saturated or unsaturated hydrocarbon radical of
from one to about 20 carbon atoms, and the keto di
carboxylic acids, such as the ketosuccinic acids, including
oxalacetic acid itself, ketoglutaric acid, and the like.
phonic acid, and the corresponding compounds of the ole
?n monocarboxylic acid series, such as l-carboxy-l-hy
ammonium salts.
ply by incorporating suitable quantities of the l-carboxy
l-hydroxyaliphatic phosphonic acids into the water or
other aqueous liquid to be protected against metal ion
precipitation. As has been indicatedrabove, these se
questrants function most efficiently when the aqueous
liquid has a pH between 6 and about 11; however, larger
quantities will work satisfactorily at lower pH values.
Ordinarily one gram atom of the sequestrant will solubilize
three gram atoms of ferric iron, for instance, and there
fore the invention can be practiced by adding one-third of
55 a gram mol of the l-carboxy-l-hydroxy aliphatic phos
phonic acid or its water-soluble salt, such as an alkali
metal or ammonium salt, for each gram atom of iron or
the like present in the solution.
Although the novel sequestering agents of the invention
acids of the series from glyoxylic acid (HCO.COOH) to
are of general utility wherever it is desired to prevent the
alpha-ketostearic acid are the most common and consti 60 precipitation of the hydroxides or sul?des of metals, such
tute the preferred starting materials to be used in pre
‘as iron hydroxide, iron sul?de, or the like, they are of
paring the phosphonic acid sequestrants of the instant in
especial importance in subterranean water-?ooding opera
vention. Many of the l-carboxy-l-hydroxy-alkylphos
tions, such as those used for the secondary recovery of
phonic acids prepared from these ketoaliphatic acids are
new chemical compounds, and therefore their preparation 65 petroleum.
It is well known that the quantity of 'oil that can be
is described in detail in the following examples. l-car
The saturated alpha-keto(aliphatic)monocarboxylic
recovered from a well drilled into an oil-bearing forma
tion can be increased by forcing an aqueous ?ooding
droxymethylphosphonic acids are the preferred seques
liquid through the formation toward an output well lo
trants to be used in practicing the invention since, by rea
son of their relative cheapness and ease of preparation as 70 cated therein. Ordinarily a ?ooding liquid, which may
- well as their low molecular weights, they constitute in
expensive and highly e?icient iron sequestrants.
be water or may contain other solutes, such as viscosity
increasing agents, such as sugars, polyacrylamides, and
the like, is introduced into the formation through several
input wells located around each production well. The
presence‘ of dissolved’ iron, for example, in such ?ooding
liquids creates a particularly troublesome di?iculty be
cause it is apt to precipitate by contact with limestone or
other alkaline strata and cause plugging of the forma
When 5 parts per million of ferric iron is added to water
containing 5 parts per million of l-carboxy-l-hydroxy
tion, thus actually reducing the quantity of petroleum
methylphosphonic acid as described in Example I, the
that can be recovered. When this feature of the inven
compound proves to be a good sequestering agent.
tion is practiced small quantities on the order of about
1/3 to 1 mol of a l-carboxy-l-hydroxyaliphatic phosphonic 10
acid or its alkali metal salt for each atom of dissolved
Fifty milligrams of trisodium l-carboxy-l-hydroxy
iron is added to the ?ood water, thus preventing such iron
ethylphosphonic acid is dissolved in 500 milliliters of
water. The pH is adjusted with caustic to 9. A stand
The invention will be further described and illustrated
by the following speci?c examples which set forth pre 15 ardized solution of a metal salt is titrated into the alkaline
solution, whose pH is held at 9 by the concurrent addi~
ferred embodiments thereof. It will be understood, how
tion of base. During the titration, small aliquots are
ever, that the invention in its broader aspects is not limited
examined. The amount sequestered is equal to the sample
by these examples, and that modi?cations and substitu
containing the largest amount of metal without precipita
tions of equivalents may be restorted to within the scope
of the appended claims.
20 tion. The following results are achieved:
Table I
A reaction ?ask immersed in a water bath is charged
with 88 grams (1 mol) of pyruvic acid and phosphorus
trichloride is added with agitation while maintaining the 25
Metal seques
temperature below 35 ° C. A total of 145 grams of PC13
is added, after which the agitation is continued for about
2-3 hours until the evolution of HCl is complete. There
is then added 180 grams of glacial acetic acid and the
mixture is maintained at about 20° C.—30° C. for an
additional 12 hours. It is then poured into ice water
and agitated until hydrolysis is complete, after which
the water is evaporated on a steam bath. The resulting
oily product is recrystallized from glacial acetic acid,
whereupon l-carboxy-l-hydroxyethylphosphonic acid is
tered (in milli
grams) per 50
milligrams of
Following the procedure of Example I, l-carboxy-l
obtained in the form of water-soluble crystals.
This compound is dissolved in water to a concentration
of 10 parts per million. A water solution of ferric
chloride is then added followed by sufficient alkali to
hydroxyisobutylphosphonic acid is prepared from di
methyl pyroracemic acid and a slight excess of PCl3.
When added to acidi?ed water containing dissolved iron
it prevents the precipitation of ferric hydroxide when
a sample is stored for two days in contact with calcite.
maintain the pH at 7.0. It is found that the l-carboxy 40
l-hydroxyethylphosphonic acid sequesters and prevents
The -carboxy-l-hydroxyalkylphosphonic acid com
the precipitation of its own weight of iron, whereas
pounds can also be prepared by heating alpha-ketoali
an untreated sample of water develops a precipitate of fer
phatic carboxylic acids or their esters with phosphorous
ric hydroxide upon the ?rst addition of ferric chloride
and alkali.
acid. Thus, for example, by heating together equimolec
ular quantities of H3PO3 and ethyl pyroracemate the ethyl
ester of l-carboxy-l-hydroxyethylphosphonic acid is ob
A sample of the l-carboxy-l-hydroxyethylphosphonic
tained. Similarly, the diethyl ester of 1,3-dicarboxy-1-hy
acid of Example I is dissolved in water and neutralized
by adding sodium hydroxide. Upon evaporation of the
droxypropylphosphonic acid is produced by heating phos
phorus acid with diethyl alpha-ketoglutarate. These
hygroscopic solid.
esters are also water-soluble compounds which sequester
dissolved iron, although they are not as efficient for this
solution to dryness the disodium salt is obtained as a 50
Another sample of the same acid is dissolved in water
and suf?cient sodium hydroxide is added to bring the
pH to 9.8. Upon evaporation of the solution the triso
dium salt is obtained.
These salts are added to samples of water containing
dissolved ferric iron which are then adjusted to pH values
of 6.0, 7.0, 8.0, 10.0 and 11.0 by the addition of sodium
hydroxide. It is found that the l-carboxy-l-hydroxy
purpose as are the free acids and their water-soluble salts.
However, the esters are readily hydrolyzed to the free
55 acids; in fact, this hydrolysis takes place to a considerable
extent when the keto-acid esters are heated with phos
phorous acid in the presence of water, as when aqueous
phosphorous is used. It Will be understood, therefore, that
the procedure described is a convenient alternative method
ethylphosphonic acid functions as ‘an iron sequestrant 60 for preparing the acids as well as their esters.
The l-carboxy-l-hydroxyalkylphosphonic acids can
throughout the entire range and that one gram mol of
be prepared by heating the alpha-keto acids with
the compound sequesters at least three gram atoms
water-soluble salts of phosphorous acid, such as the alkali
of iron at pH values between 6 and about 10.
metal or ammonium salts, with disodium hydrogen phos
The correspond
ing water-soluble salts of the keto acids can also be reacted
with phosphorous acid.
The cooled reaction ?ask of Example I is charged with
While the activity of the sequestrants contemplated
74 grams (1 mol) of glyoxylic acid (HCOCOOH) and
145 grams of PCla is added with agitation and cooling
herein with respect to a number of heavy metals has been
below 35° C. After reaction is‘ complete there is added 70 demonstrated hereinabove, the invention is by no means
3 gram mols of glacial acetic acid and the mixture allowed
limited thereto. The sequestrants of the instant discovery
to stand overnight. It is then drowned in ice water, evap
are useful in sequestering all heavy metal cations which
orated on the steam bath and dried three days in a desic
at a pH of 6 to 11 form insoluble precipitates, such as
cator. The resulting compound is l-carboxy-l-hydroxy
hydroxides and the like, in aqueous media.
methylphosphonic acid of the formula
65 phite, preferably in aqueous solution.
Other heavy metal ions sequestered by the l-carboxy
l-hydroxy aliphatic phosphonic acids and their water-solu
5. The method of claim 2 wherein the heavy metal ca
tion is copper.
6. The method of claim 2 wherein the phosphonic acid
ble salts in the manner described in the above examples
are lead, titanium, chromium, and the like.
Clearly, the instant discovery encompasses numerous
modi?cations within the skill of the art. Consequently,
while the present invention has been described in detail
with respect to speci?c embodiments thereof, it is not in
is l-carboxy-l-hydroxyethylphosphonic acid.
7. The method of claim 2 wherein the phosphonic acid
is l-carboxy-l-hydroxymethylphosphonic acid.
8. A method for the secondary recovery of petroleum
from a subterranean oil-bearing formation which com
tended that these details be construed as limitations upon
prises forcing through said formation toward an output
the scope of the invention, except insofar as they appear
10 well located therein an aqueous ?ooding liquid contami
in the appended claims.
nated by small quantities of dissolved heavy metal cat
We claim:
ions which have a tendency to form insoluble precipitates
1. -.A method of inhibiting the precipitation of heavy
and also containing, in metal cation-sequestering amounts,
metal cations from an aqueous solution containing said
a sequestrant selected from the group consisting of phos
cations which comprises incorporating therein heavy metal
cation-sequestering quantities of a sequestrant selected 15 phonic acids of the formula
from the group consisting of phosphonic acids of the for
H0 0 0
in which R is a member of the group consisting of hydro
gen and the residue of an alpha-ketocarboxylic acid of
in which R is a member of the group consisting of hydro
gen and the residue of an alpha-ketocarboxylic acid of
from one to 20 carbon atoms, and alkali metal and am
monium salts of said phosphonic acids.
9. A method of inhibiting the precipitation of iron from
from one to 20 carbon atoms, and alkali metal and am 25
petroleum production Waters which comprises incorporat
monium salts of said phosphonic acids.
ing therein sequestering quantities of a sequestrant se~
2. A method of inhibiting the precipitation of heavy
lected from the group consisting of phosphonic acids of
metal cations from an aqueous solution having a pH with
the formula
in the range of 6 to 11 and containing said cations, said
cations having a tendency to form insoluble precipitates, 30
E0 O 0
which comprises incorporating therein in a quantity of
at least one gram mol for each three gram atoms of heavy
metal cation in said solution a sequestrant selected from
the group consisting of phosphonic acids of the formula
35 in which R is a member of the group consisting of hydro
gen and the residue of an alpha-ketocarboxylic acid of
from one to 20 carbon atoms, and alkali metal and am
monium salts of said phosphonic acids.
in which R is a member of the group consisting of hydro 40
gen and the residue of an alpha-ketocarboxylic acid of
References Cited in the ?le of this patent
from one to 20 carbon atoms, and alkali metal and am
monium salts of said phosphonic acids.
3. The method of claim 2 wherein the heavy metal
cation is iron.
4. The method of claim 2 wherein the heavy metal ca
tion is nickel.
Morgan ______________ __ Aug. 23, 1938
Garrison _____________ __ June 24, 1941
Cocks ______________ __ Sept. 16, 1958
Buckler et al. ________ __ July 29, 1958
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