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Description  |
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BACKGROUND OF THE INVENTION
This invention relates to novel hydroxy ether carboxylate salts useful as
complexing agents and detergency builders, to ester and acid forms of such
compounds useful as intermediates for preparation of the salts, to methods
of preparing the ester, acid and salt compounds, and to detergent
formulations containing the salt compounds.
The utility of compounds characterized by the ability to complex various
metal and alkaline earth metal ions (particularly ions such as calcium
ions which contribute to "hardness" of water) in aqueous media and/or
provide, in combination with various detergent surfactants, detergent
formulations of enhanced cleansing ability is well recognized by those
skilled in the art. Such compounds are used in water treating applications
(e.g. to "soften" water) and/or as detergency builders.
Although many compounds having complexing and/or detergency builder
functionality are known, the provision of novel compounds composed of only
carbon, hydrogen and oxygen and having such functionality is desirable.
SUMMARY OF THE INVENTION
It is an object of this invention to provide novel compounds useful as
complexing agents and/or detergency builders and intermediates for the
synthesis of such compounds.
The compounds of this invention are hydroxy ether polycarboxylic acids,
salts and esters whose structure, synthesis, and use will be understood
from the following description of the preferred embodiments.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The compounds of the present invention are represented by the formula
##EQU2##
wherein X is hydrogen, alkyl containing from 1 to 20 carbon atoms, alkali
metal, ammonium, alkyl ammonium containing from 1 to 4 carbon atoms or
alkanol ammonium containing from 1 to 4 carbon atoms and A is hydrogen,
methyl, ethyl or CH.sub.2 OH.
The ester and acid forms of the compounds of this invention are useful as
intermediates for preparation of the salt forms as will be apparent from
the description of methods of preparing compounds of this invention.
The ester forms of the compounds of this invention are prepared by reacting
an ether carboxylate ester represented by the formula
##EQU3##
(wherein R is an alkyl group containing from 1 to 20 carbon atoms and Y is
hydrogen, methyl or ethyl) with formaldehyde.
The formaldehyde can be provided directly or materials capable of providing
formaldehyde under reaction conditions (e.g. paraformaldehyde, trioxane)
can be utilized. Methanol stabilized aqueous formaldehyde solutions
(formalin) provide a particularly convenient source of formaldehyde.
The reaction is conducted in a medium sufficiently basic to deprotonate but
not so basic as to substantially (more than 30%) hydrolyze or saponify the
ether carboxylate ester. This degree of basicity is conveniently obtained
with a weak base such as potassium bicarbonate. Preferred reaction
temperatures are in the range of 15.degree.C to 30.degree.C although
higher or lower temperatures (generally in the range of 5.degree.C to
200.degree.C) can be utilized if desired. At higher temperatures,
appropriate pressure or reflux means are desirably employed.
The starting ether carboxylate esters can be prepared from diethyl
diglycolate, diethyl methyldiglycolate or diethyl ethyldiglycolate which
are, respectively, prepared by adding ethyl glycolate, ethyl lactate, or
ethyl 2-hydroxybutyrate to sodium hydride slurried in tetrahydrofuran
cooled to about 15.degree.C and adding ethyl bromoacetate. The diglycolate
product is recovered by evaporating solvent, washing the residue with
water to remove salts, drying and distillation.
The diglycolate in tetrahydrofuran solution is added (at about
-75.degree.C) to a mixture formed by adding n-butylithium to a
tetrahydrofuran solution of diisopropylamine.
It is believed that this procedure results in formation of a lithium salt
represented by the formula
##EQU4##
(m is an integer from 0 to 2.)
Gaseous CO.sub.2 is then introduced to form
##EQU5##
which is dissolved in water and converted to a half-ester half-acid:
##EQU6##
by treatment with a strong acid ion exchange resin (e.g. a sulfonated
polystyrene resin such as marketed by Fischer Scientific Company under the
trademark Rexyn 101).
The half-ester half-acid is completely esterified by dissolving in ethyl
alcohol and benzene and acidifying with concentrated sulfuric acid in
accordance with conventional esterification practice. The acid forms of
the starting ether carboxylate esters can be obtained by conventional
techniques (e.g. saponification followed by acidulation) and used to
prepare higher ester starting materials, if desired.
If the starting ester
##EQU7##
is reacted with amounts of formaldehyde less than stoichemetric for
formation of
##EQU8##
a mixture of this material with
##EQU9##
will be obtained. This mixture (or acids or salts thereof) can be used as
such or the individual compounds can be isolated by conventional
techniques.
The corresponding alkali metal salt forms of the compounds of this
invention are readily obtained by conventional saponification techniques.
The corresponding ammonium and alkanol ammonium salts are more easily
obtained by neutralization of the acid forms of the compounds of this
invention.
Acidulation of the salt with a strong acid, e.g., HCl, H.sub.2 SO.sub.4, or
a strong acid ion exchange resin, will yield the acid forms of the
compounds of this invention.
The hydroxyether polycarboxylate salts of this invention are useful as
agents for complexing metal and/or alkaline earth metal ions in aqueous
media. The amount of polycarboxylate required to effectively complex the
ions in a given system will depend, to some extent, on the particular
polycarboxylate salt being used and the particular metal or alkaline earth
metal ions in the aqueous media. Generally, complexing is more effective
in basic solution. Optimum conditions and amounts of complexing agent can
readily be determined by routine experimentation.
The hydroxy ether polycarboxylate salts are also useful as builders in
detergent formulations. Generally, the use of the alkali metal salts,
particularly the sodium salt is preferred. However, in some formulations
(such as liquid formulations where greater builder solubility is required)
the use of ammonium or alkanol ammonium salts may be desirable.
The detergent formulations will contain at least 1% by weight and
preferably at least 5% by weight of the hydroxy ether polycarboxylate
salts of this invention. In order to obtain the maximum advantages of the
builder compositions of this invention, the use of from 5% to 75% of these
polycarboxylate salts is particularly preferred. The hydroxy ether
polycarboxylate salt compounds of this invention can be the sole
detergency builder or these compounds can be utilized in combination with
other detergency builders which may constitute from 0 to 95% by weight of
the total builders in the formulation. By way of example, builders which
can be employed in combination with the novel builder compounds of this
invention include water soluble inorganic builder salts such as alkali
metal polyphosphates, i.e., the tripolyphosphates and pyrophosphates,
alkali metal carbonates, borates, bicarbonates and silicates and water
soluble organic builders including amino polycarboxylic acids and salts
such as alkali metal nitrilotriacetates, cycloalkane polycarboxylic acids
and salts, ether polycarboxylates (for example, the salt forms of the
esters reacted to prepare the ester forms of the compounds of the present
invention), alkyl polycarboxylates, epoxy polycarboxylates,
tetrahydrofuran polycarboxylates such as 1,2,3,4 or 2,2,5,5
tetrahydrofuran tetracarboxylates, benzene polycarboxylates, oxidized
starches, amino (trimethylene phosphonic acid) and its salts, diphosphonic
acids and salts (e.g., methylene diphosphonic acid; 1-hydroxy ethylidene
diphosphonic acid) and the like.
The detergent formulations will generally contain from 5% to 95% by weight
total builder (although greater or lesser quantities may be employed if
desired) which, as indicated above, may be solely the hydroxy ether
polycarboxylate salt compounds of this invention or mixtures of such
compounds with other builders. The total amount of builder employed will
be dependent on the intended use of the detergent formulation, other
ingredients of the formulation, pH conditions and the like. For example,
general laundry powder formulations will usually contain 20% to 60%
builder, liquid dishwashing formulations 11% to 12% builder; machine
dishwashing formulations 60% to 90% builder. Optimum levels of builder
content as well as optimum mixtures of builders of this invention with
other builders for various uses can be determined by routine tests in
accordance with conventional detergent formulation practice.
The detergent formulations wll generally contain a water soluble detergent
surfactant although the surfactant ingredient may be omitted from machine
dishwashing formulations. Any water soluble anionic, nonionic,
zwitterionic or amphoteric surfactant can be employed.
Examples of suitable anionic surfactants include soaps such as the salts of
fatty acids containing about 9 to 20 carbon atoms, e.g. salts of fatty
acids derived from coconut oil and tallow; alkyl benzene
sulfonates--particularly linear alkyl benzene sulfonates in which the
alkyl group contains from 10 to 16 carbon atoms; alcohol sulfates;
ethoxylated alcohol sulfates; hydroxy alkyl sulfonates; alkenyl and alkyl
sulfates and sulfonates; monoglyceride sulfates; acid condensates of fatty
acid chlorides with hydroxy alkyl sulfonates and the like.
Examples of suitable nonionic surfactants include alkylene oxide (e.g.,
ethylene oxide) condensates of mono and polyhydroxy alcohols, alkyl
phenols, fatty acid amides, and fatty amines; amine oxides; sugar
derivatives such as sucrose monopalmitate; long chain tertiary phosphine
oxides; dialkyl sulfoxides; fatty acid amides, (e.g., mono or diethanol
amides of fatty acids containing 10 to 18 carbon atoms), and the like.
Examples of suitable zwitterionic surfactants include derivatives of
aliphatic quaternary ammonium compounds such as
3-(N,N-dimethyl-N-hexadecyl ammonio) propane-1-sulfonate and
3-(N,N-dimethyl-N-hexadecyl ammonio)-2-hydroxy propane-1-sulfonate.
Examples of suitable amphoteric surfactants include betains, sulfobetains
and fatty acid imidazole carboxylates and sulfonates.
It will be understood that the above examples of surfactants are by no
means comprehensive and that numerous other surfactants are known to those
skilled in the art. It will be further understood that the choice and use
of surfactants will be in accordance with well understood practices of
detergent formulation. For example, anionic surfactants, particularly
linear alkyl benzene sulfonate are preferred for use in general laundry
formulations, whereas low foaming nonionic surfactants are preferred for
use in machine dishwashing formulations.
The quantity of surfactant employed in the detergent formulations will
depend on the surfactant chosen and the end use of the formulation. In
general, the formulations will contain from 5% to 50% surfactant by
weight, although as much as 95% or more surfactant may be employed if
desired. For example, general laundry powder formulations normally contain
5% to 50%, preferably 15% to 25% surfactant; machine dishwashing
formulations 0.5% to 5%; liquid dishwashing formulations 20% to 45%. The
weight ratio of surfactant to builder will generally be in the range of
from 1:12 to 2:1.
In addition to builder and surfactant components, detergent formulations
may contain fillers such as sodium sulfate and minor amounts of bleaches,
dyes, optical brighteners, soil anti-redeposition agents, perfumes and the
like.
In machine dishwashing compositions the surfactant will be a low-foaming
anionic or preferably, nonionic surfactant which will constitute 0 to 5%
of the formulation.
The term "low-foaming" surfactant connotes a surfactant which, in the
foaming test described below, reduces the revolutions of the washer
jet-spray arm during the wash and rinse cycles less than 15%, preferably
less than 10%.
In the foaming test, 1.5 grams of surfactant is added to a 1969 Kitchen-Aid
Home Dishwasher, Model No. KOS-16, manufactured by Hobart Manufacturing
Company which is provided with means for counting revolutions of the
washer jet-spray arm during wash and rinse cycles. The machine is operated
using distilled water feed at a machine entrance temperature of
40.degree.C. The number of revolutions of the jet-spray arm during the
wash and rinse cycles is counted. The results are compared with those
obtained by operation of the machine using no surfactant charge and the
percentage decrease in the number of revolutions is determined.
The surfactant should, of course, be compatible with the chlorine
containing component hereinafter discussed. Examples of suitable nonionic
surfactants include ethoxylated alkyl phenols, ethoxylated alcohols (both
mono- and di- hydroxy alcohols), polyoxyalkylene glycols, aliphatic
polyethers and the like. The widely commercially utilized condensates of
polyoxypropylene glycols having molecular weights of from about 1400 to
2200 with ethylene oxide (the ethylene oxide constituting 5 to 35 weight
percent of the condensate) are, for example, advantageously used in the
machine dishwashing formulations of this invention.
Suitable low-foaming anionic surfactants include alkyl diphenyl ether
sulfonates such as sodium dodecyl diphenyl ether disulfonates and alkyl
naphthalene sulfonates.
Mixtures of suitable low-foaming surfactants can be utilized if desired.
In addition, machine dishwashing formulations will contain sufficient
chlorine providing compound to provide 0.5% to 2% available chlorine. For
example, the formulation may contain from 0.5% to 5%, preferably 1% to 3%
of a chlorocyanurate or from 10% to 30% chlorinated trisodium phosphate.
Suitable chlorocyanurates are sodium and potassium dichlorocyanurate;
[(monotrichloro) tetra-(monopotassium dichloro)] penta-isocyanurate;
(monotrichloro) (monopotassium dichloro) diisocyanurate.
Machine dishwashing compositions should additionally contain from 5% to 30%
soluble sodium silicate having an SiO.sub.2 to Na.sub.2 O mole ratio of
from 1:1 to 3.2:1 preferably about 2.4:1 to inhibit corrosion of metal
parts of dishwashing machines and provide over-glaze protection to fine
china.
Machine dishwashing compositions will generally contain at least 10%,
preferably at least 20% builder, up to a maximum of about 90% builder. The
new builder compounds of this invention should constitute at least 5% of
the weight of the machine dishwashing formulation in order to obtain the
full effects of their inherent characteristics.
EXAMPLE I
Diethyl diglycolate is prepared by slurrying 270 parts sodium hydride in
2800 parts tetrahydrofuran and adding 705 parts ethyl glycolate to the
mixture while maintaining the temperature between 10.degree. to
15.degree.C. The mixture is stirred for 1 hour at 25.degree.C, cooled to
15.degree.C and 894 parts ethyl bromoacetate is added. The mixture is
stirred for 12 hours at 25.degree.C; solvent evaporated; residue washed
with water to remove salts; dried and purified diethyl digylcolate
recovered by distillation under reduced pressure. (Note: Diethyl
methylglycolate or diethyl ethyldiglycolate are prepared by similar
procedures wherein ethyl lactate (800 parts) or ethyl-2-hydroxybutyrate
(895 parts) are, respectively, substituted for the ethyl glycolate.)
A solution of 21 parts diethyl diglycolate in 100 parts tetrahydrofuran is
added to a mixture prepared by adding 115 parts 2.3 molar n-butyl lithium
to a solution of 24 parts diisopropylamine in 400 parts tetrahydrofuran
cooled to -30.degree.C. The resulting mixture is allowed to warm to
-10.degree.C for about 10 minutes and then cooled to -75.degree.C. A
solution of 21 parts diethyl diglycolate in 100 parts tetrahydrofuran is
added while maintaining the temperature below -70.degree.C.
Gaseous CO.sub.2 is passed through the mixture which is maintained at
-45.degree.C to -75.degree.C for 1 hour. The temperature is then allowed
to rise to 25.degree.C while maintaining CO.sub.2 flow.
Tetrahydrofuran is evaporated leaving a residue which is dissolved in water
and passed through a strong acid ion exchange column (packed with a
sulfonated polystyrene resin marketed by Fischer Scientific Company under
the trademark Rexyn 101).
High vacuum evaporation of the water leaves a thick syrup-like residue
which is completely esterified to form tetraethyl oxydimalonate by
dissolving in 25 parts ethanol, 40 parts benzene and 0.2 parts
concentrated sulfuric acid; azeotropically removing water; adding 3 parts
additional ethanol; distilling off excess alcohol and benzene. The residue
is dissolved in benzene; washed with 5% NaHCO.sub.3 and water; dried over
MgSO.sub.4 ; stripped of benzene by evaporation and distilled. The
tetraethyl oxydimalonate is collected in the range of 141.degree. to
143.degree.C, 0.05 mm. Hg. (Note: tetraethyl 2-methyl oxydimalonate or
tetraethyl 2-ethyl oxydimalonate can be prepared by similar procedures in
which diethyl methyldiglycolate or diethyl ethyldiglycolate is substituted
for the diethyl diglycolate.)
The tetraethyl oxydimalonate (34 parts) is added to a rapidly stirred
solution of 2 parts KHCO.sub.3 dissolved in 33 parts formalin (37%
formaldehyde). The temperature is maintained between 35.degree. to
40.degree.C during the slightly exothermic reaction which yields
tetraethyl 2,2'-bis(hydroxymethyl)oxydimalonate
##EQU10##
Addition of 70 parts, 25% NaOH aqueous solution saponifies the ester to
tetrasodium 2,2'-bis(hydroxymethyl)oxydimalonate
##EQU11##
which is separated by addition of excess methanol. The salt is purified by
dissolving in water; adding ethanol to separate an oil which is triturated
in acetone to give the product as a granular white powder.
The tetrasodium 2,2'-bis(hydroxymethyl)oxydimalonate has a hydrogen nuclear
magnetic resonance spectrum (determined in deuterium oxide) exhibiting
singlets at about 5 ppm (OH protons of the methylol groups) and at about
4.3 ppm (CH.sub.2 protons).
EXAMPLE II
Tetrasodium 2,2'-bis(hydroxymethyl)oxydimalonate is tested for
sequestration function using the procedures described by Matzner et al,
"Organic Builder Salts as Replacements for Sodium Tripolyphosphate",
Tenside Detergents, 10, Heft 3, pages 119-125 (1973).
The sequestration value (intensity multiplied by capacity expressed as a
percentage of sodium tripolyphosphate sequestration value) of tetrasodium
2,2'-bis(hydroxymethyl)-oxydimalonate is 127%.
EXAMPLE III
Detergent formulations containing the percent builder shown in Table I
below; 17% linear alkylbenzene sulfonate having an average molecular
weight of about 230; 6% sodium silicate; remainder, sodium sulfate are
prepared. The formulations are tested by washing identically soiled fabric
swatches (indicated in the table) in water of 200 ppm hardness at
49.degree.C containing 0.15% detergent formulation using identical washing
techniques. The reflectivity of the soiled swatches before and after
washing is measured instrumentally and the difference reported in Table I
as .DELTA. Rd. High .DELTA. Rd values are indicative of correspondingly
high detergency effectiveness.
TABLE I
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Cotton Fabric .DELTA.Rd
Polyester/Cotton Fabric .DELTA. Rd
% Builder % Builder
Builder 50
37.5
25
50 37.5 25
__________________________________________________________________________
none (a filler-
<13 <13 <13 <5 <5 <5
sodium sulfate-
is used in place
of builder)
tetrasodium 2,2'
29.2
18.1
13.8
9.1 8.6 5.4
bis(hydroxy-
methyl)oxydi-
malonate
__________________________________________________________________________
The data presented in Table I show the salt forms of the compounds of this
invention to be effective detergency builders.
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Description |
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