Dialkylamino-N,N-bis(phosphonoalkylene)alkylamines and use in aqueous systems as precipitation and corrosion inhibitors

Dialkylamino-N,N-bis(phosphonoalkylene)alkylamines, salts, and specifically the hydrochlorides thereof prepared by reacting an unsymmetrical dimethylaminoalkylamine hydrochloride with phosphorous acid and an aldehyde are useful in various industrial processes including acting as corrosion and scale inhibitors in aqueous systems wherein such corrosion and scale problems exist. Quaternized dialkylamino-N,N-bis(phosphonoalkylene)alkylamines suitable for the same uses are prepared by the treatment of an aqueous solution of a dialkylamine-N,N-bis(phosphonoalkylene)alkylamine with an epoxide or a halohydrin.

BACKGROUND OF THE INVENTION 
Cooling water systems are subject to formation of scale deposits. Scaling 
can occur when the concentration of a dissolved substance in a cooling 
water becomes greater than its solubility in the water. It can especially 
be a problem with a substance that has an inverse solubility curve; that 
is, a material whose solubility decreases as the temperature increases. 
Since water temperatures at or near heat-transfer surfaces are greater 
than temperatures in the bulk of the system, the solubility of such 
materials is less in these regions. Consequently, they tend to precipitate 
and form scales that reduce heat-transfer efficiency. 
One principal scale-forming material encountered in cooling water systems 
is calcium carbonate formed by the decomposition of calcium bicarbonate. 
This compound not only has an inverse solubility curve, but its solubility 
is much lower in most typical cooling waters than almost all other 
potential scale-formers that might be present in these waters. Of course, 
calcium carbonate is soluble in acidic solutions, and as the pH of a 
cooling water is lowered, scale generally becomes less of a problem. 
However, most cooling waters are kept on the alkaline side to reduce 
corrosion, and thus calcium carbonate scaling remains as a potential 
problem. Calcium sulfate, calcium phosphate, barium sulfate, and ferric 
hydroxide can also cause scale. Thus, to be a broadly useful composition, 
a scale control product must be capable of controlling different scale 
types. 
It is well known that the operation of commercial and industrial cooling 
systems is adversely affected by a number of different factors. Of these 
adverse factors, corrosion of metallic parts coming into contact with the 
water is probably one of the most serious. If not controlled, corrosion 
causes the rapid deterioration of the metallic materials of construction 
used in cooling towers and associated equipment such as pumps, pipelines 
and valves, causing major losses in overall efficiency of the cooling 
systems. While control of bleedoff, pH, and other operating variables is 
helpful in reducing corrosion, chemical treatment of the water is 
generally the most effective and economical means of minimizing this 
problem, particularly where conservation of water by means of recycling is 
necessary or desired. 
Waterside problems encountered in boilers and steam systems include the 
formation of scale and other deposits, corrosion, and foam. Scale and 
other deposits on heat-transfer surfaces can cause loss of the thermal 
efficiency of the boiler and can make the temperatures of the boiler metal 
increase. Under scaling conditions, temperatures may go high enough to 
lead to failure of the metal due to overheating. Corrosion in boilers and 
steam systems also causes failure of boiler metal and damage to steam and 
condensate lines. 
The principal source of deposits in boilers is dissolved mineral matter in 
the boiler feedwater. The term "scale" is generally used for deposits that 
adhere to boiler surfaces exposed to the water, while nonadherent deposits 
are called "sludge" or "mud." Scale causes more difficulty because the 
sludge can be purged from the system with the blowdown or can be easily 
washed out, but scale can normally only be removed by mechanical or 
chemical cleaning of the boiler. 
In natural, untreated water, the main sources of scale and sludge are 
calcium carbonate, calcium sulfate, magnesium hydroxide, and silica. The 
most common type of scale in boilers is probably calcium carbonate, but 
the most troublesome is usually calcium sulfate. The latter causes more 
difficulties because its solubility decreases more rapidly with increasing 
temperatures than does that of other substances, and the scale it forms is 
hard, dense, and difficult to remove. On the other hand, calcium carbonate 
tends to form sludge more than scale, and the calcium carbonate scales 
that do form are generally softer and easier to remove. Magnesium 
hydroxide precipitates are not very adherent and tend to form sludges 
rather than scales. 
It is often desirable in today's technology to prevent precipitation of 
alkaline earth salts or of iron salts from water or aqueous solutions. For 
this purpose inorganic and organic sequestering agents have previously 
been proposed and utilized. For instance, the organic compounds nitrilo 
triacetic acid or ethylenediamine tetraacetic acid have been used. 
Likewise polymeric phosphates have also been used as sequestering agents. 
The latter have the advantage that they can prevent precipitation even if 
applied in less than a stoichiometric amount. The disadvantages of the 
polymeric phosphates, however, are that they lose effectiveness at 
elevated temperatures and that they readily hydrolyze, particularly in the 
acidic pH range. For reasons related to sewage disposal, additional 
problems may develop in the use of phosphates. It has already been 
proposed to use organic phosphonic acids, such as non-substituted 
aminotrimethylene phosphonic acid, for this purpose, but it has been found 
that corrosion problems occur therefrom. 
Aminoalkylenephosphonic acids and their metal and ammonium salts are well 
known compounds and recognized metal complexing agents. The quaternization 
of such compounds in an aqueous solution has not heretofore been achieved. 
Under normal reaction conditions, there is apparent protonation (or 
zwitter ion formation) of the free electrons on the nitrogen atoms in the 
molecule. Conditions which are sufficiently alkaline to remove said proton 
tend to destroy the alkylating agent faster than it can react in the 
desired fashion. 
OBJECTS OF THE INVENTION 
It is an object of the present invention to provide novel 
dialkylamino-N,N-bis(phosphonoalkylene)amine hydrochlorides having 
valuable properties. 
It is another object of our invention to provide the alkali metal and 
ammonium salts of such compounds. 
It is a further object of our invention to provide a process for inhibiting 
the precipitation of insoluble salts from aqueous solutions comprising 
adding to an aqueous solution containing a precipitable salt, a 
composition selected from the group consisting of (a) a 
dialkylamino-N,N-bis(phosphonoalkylene)alkylamine, (b) hydrochloride 
thereof, (c) alkali metal salt or ammonium salt thereof, and (d) 
quaternary ammonium derivatives thereof. 
It is yet another object of this invention to provide a process for 
inhibiting the corrosion of metals in contact with an aqueous system 
comprising adding thereto a composition selected from the group consisting 
of (a) a dialkylamino-N,N-bis(phosphonoalkylene)alkylamine, (b) 
hydrochloride thereof, (c) alkali metal salt or ammonium salt thereof, and 
(d) quaternary ammonium derivatives thereof. 
A further object of this invention is to provide a composition that is 
compatible with other water treatment agents to achieve maximum efficiency 
in the control of both scale and corrosion. 
These and other objects and advantages will become apparent as the 
description proceeds. 
SUMMARY OF THE INVENTION 
According to the present invention it has been found that certain 
dialkylamino-N,N-bis(phosphonoalkylene)alkylamines and their alkali metal 
or ammonium salts, corresponding to the formula 
##STR1## 
wherein R.sup.1 and R.sup.2 represent an alkyl group containing 1 to 4 
carbon atoms, R.sup.3 and R.sup.4 represent hydrogen or an alkyl group 
containing 1 to 4 carbon atoms, M represents hydrogen, an alkali metal or 
ammonium, and n is an integer varying from 2 to 6 and further 
characterized in that when M is hydrogen the composition is a hydrohalide 
salt and their quaternary ammonium salts formed by reacting the alkali 
metal salts thereof with halohydrins or epoxides. These compounds are 
precipitation inhibitors and corrosion inhibitors when used in 
stoichiometric and substiochiometric amounts, including that phenomenon 
known in the art as the `threshold effect.` 
DESCRIPTION OF PREFERRED EMBODIMENTS 
The dialkylamino-N,N-bis(phosphonoalkylene)alkylamine hydrochloride of the 
present invention may be prepared by reacting an unsymmetrical 
dimethylaminoalkylamine hydrochloride with phosphorous acid and an 
aldehyde in the proper molecular proportions. Variations in specific 
structure of the compounds are possible through variations in the value of 
n and in the structure of R.sup.1, R.sup.2, R.sup.3, and R.sup.4. 
The preferred dialkylamino-N,N-bis(phosphonoalkylene)alkylamine 
hydrochloride is 
##STR2## 
where n is 3. 
Derivatives of dialkylamino-N,N-bis(phosphonoalkylene)alkylamines may be 
prepared by reacting their alkali metal salts with a halohydrin or an 
epoxide in the proper molecular proportions as described in the examples. 
Variations in specific structure of these compounds are possible through 
variations in the value of n and in the structure of R.sup.1, R.sup.2, 
R.sup.3, and R.sup.4. These compounds were identified by titration values 
and by their characteristic NMR and infrared bands as quaternized 
dialkylamino-N,N-bis(phosphonoalkylene)alkylamines. 
The amines used in the preparation of the compositions of this invention 
contain on primary amine and at least one secondary or tertiary amine such 
as unsym. N,N-dimethylethylenediamine and unsym. 
N,N-dimethylaminopropylamine. 
Typical examples of suitable aldehydes are formaldehyde, acetaldehyde, 
propionaldehyde and butyraldehyde. 
Orthophosphorous acid is readily available commercially. It can be utilized 
in the process of the present invention either as the acid or in the form 
of its salts, such as its mono- or di-alkali metal salts. When 
orthophosphorous acid is utilized in the salt form, usually a small amount 
of a supplementary acid should be utilized in order to effectively convert 
the salt form into the more reactive orthophosphorous acid. 
The epoxides and chlorohydrins that can be used for the preparation of the 
quaternary ammonium salts of this invention are ethylene oxide, propylene 
oxide, epichlorohydrin, 3-chloro-1,2-propoanediol (.alpha.-chlorohydrin), 
low mmolecular weight hydroxylated ionene polymers with halogen end 
groups, etc. 
The aminoalkylenephosphonic acids and salts of our invention may be 
utilized as solids, as solutions in water or in polar organic solvents or 
in combinations of water and organic solvents. When used for scale 
inhibition, the aminoalkylenephosphonates may be used alone or in 
combination with other scale inhibitors. Examples of these would be alkali 
metal phosphates, alkali metal polyphosphates, alkali metal 
tripolyphosphates, alkali metal pyrophosphates, organic water soluble 
polymers containing a linear hydrocarbon structure with side chain 
carboxylic acid groups exemplified by the structure: 
##STR3## 
where R.sup.5 is hydrogen or --COOH and R.sup.6 is hydrogen or methyl. 
These polymers may be obtained from acrylic acid or methacrylic acid. 
Polymers of maleic anhydride can be prepared and the anhydride group 
hydrolyzed with water to provide carboxylic acid groups. Acrylonitrile and 
acrylamide polymers may also be hydrolyzed with hot alkaline solutions to 
eliminate ammonia and form carboxylic acid salts. Copolymers of all of the 
monomers listed may also be prepared and these copolymers may be 
hydrolyzed to the carboxylic acid groups if the anhydride, amide, or 
nitrile groups are contained in the copolymer. These polymers may be 
utilized as the free acid or as water soluble salts such as the alkali 
metal and alkaline earth metal salts. The polymers used in this invention 
are either commercially available or methods for their preparation are 
well known in the art. In addition, poly(acrylamide) of low molecular 
weight may be combined with the phosphonates of this invention. 
The aminoalkylenephosphonic acids of this invention can be formulated with 
such polymers as poly(acrylic acid) with both ingredients used as the free 
acids. This is advantageous when the products are used in closed systems 
such as recirculated cooling water systems. In such systems, the 
evaporation of water increases the solids content of the water and 
increases the pH at the same time, particularly if alkaline scale 
inhibitors are being added. The cycles of concentration in those systems 
can be markedly increased if the additive has an acid pH. 
The aminoalkylenephosphonates of this invention act as corrosion inhibitors 
for mild steel. Formulations of these phosphonates with corrosion 
inhibitors such as water soluble zinc salts will provide both scale 
inhibition and synergistic corrosion protection. Combinations of the 
phosphonates with 2-mercaptobenzothiazole, benzotriazole, and 
tolyltriazole will give good corrosion inhibition on both copper alloys 
and steel. Additional compounds which have been used as corrosion 
inhibitors and which can be used in combination with the 
aminoalkylene-phosphonates of this invention include phosphates, 
polyphosphates, organic water soluble polymers, silicates, 
dithiocarbamates, nitrites, oxazoles, imidazoles, lignins, 
lignosulfonates, tannins, phosphoric acid esters, boric acid esters, 
alkali metal salts of inorganic molybdenum and chromium compounds. 
To the accomplishment of the foregoing and related ends, this invention 
then comprises the features hereinafter fully described and particularly 
pointed out in the claims, the following description setting forth in 
detail certain illustrative embodiments of the invention, these being 
indicative, however, of but a few of the various ways in which the 
principles of the invention may be employed. 
The amount and manner of use of the scale, sludge, and corrosion control 
compositions of our invention are dependent on the nature of the problems 
caused by scale and sludge in the particular system. In general, suitable 
quantities of the compounds of this invention vary from 0.5 to 500 parts 
per million parts by weight of water. Preferred quantities vary from 1.0 
to 200 parts per million parts of water. It is understood, of course, that 
larger quantities may be used, but such is generally not desirable because 
coats are increased without commensurate additional beneficial results.

In order to disclose the nature of the invention still more clearly, the 
following illustrative examples will be given. It is understood, however, 
that the invention is not to be limited to the specific conditions or 
details set forth in these examples, except insofar as such limitations 
are specified in the appended claims. 
EXAMPLE 1 
3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine Hydrochloride 
To 511.0 g (5.0 moles) of 3-dimethylaminopropylamine 985.5 g of 
concentrated hydrochloric acid (10.0 moles) was added slowly at such a 
rate as to keep the temperature below 50.degree. C. during the addition. 
When the introduction of the hydrochloric acid was completed, 1171.4 g 
(10.0 moles) of phosphorous acid was added rapidly and the stirred mixture 
was heated to 60.degree. to 65.degree. C. At this point 892.8 g (11.0 
moles) of 37 percent aqueous formaldehyde was slowly introduced. The 
reaction was exothermic. After the introduction of the formaldehyde the 
mixture was refluxed for two hours. An aliquot of the resulting mixture 
was triturated under ethanol to yield a white powdery material that was 
further purified by recrystallization from hot ethyl alcohol. The compound 
was identified by its characteristic infrared spectrum and by elemental 
analysis as 3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
hydrochloride. Analysis calcd for C.sub.7 H.sub.21 ClN.sub.2 O.sub.6 
P.sub.2 : C, 25.73 percent; H, 6.48 percent; N 8.57 percent; and P, 18.96 
percent. Found: C, 25.85 percent; H, 6.76 percent; N, 8.57 percent; and P, 
19.02 percent. Melting range 165.degree.-175.degree. C. 
EXAMPLE 2 
Reaction of 3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
with Epichlorohydrin 
To a solution of 16.3 g (0.05 mole) of 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine hydrochloride 
in 30.0 g of water, 12.0 g of 50 percent sodium hydroxide solution was 
added at such a rate as to keep the temperature of the stirred mixture 
between 40.degree. and 50.degree. C. To the resulting sodium salt 
solution, 4.6 g (0.05 mole) of epichlorohydrin wasa added and the mixture 
was stirred at the reflux temperature for two hours. The resulting 
solution was tested without purification. An aliquot of the solution was 
triturated under ethanol to yield a white hygroscopic solid that was 
further purified by recrystallization from hot ethyl alcohol and dried in 
a vacuum desiccator over P.sub.2 O.sub.5. The compound was characterized 
by its distinguishing infrared and NMR bands and by titration as 
quaternary ammonium salt, but that exact structure was not precisely 
determined. 
EXAMPLE 3 
Reaction of Two Moles of 
3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine with One Mole 
of Epichlorohydrin 
Into a 1-liter, 3-neck, round-bottom flask equipped with a stirrer, 
thermometer and reflux condenser was charged 178.0 g of a 45.88 percent 
aqueous solution of 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine hydrochloride 
(0.25 mole). The pH of this solution was adjusted to 7.5-7.6 by the 
addition of 50 percent aqueous sodium hydroxide solution at such a rate as 
to keep the temperature of the stirred mixture below 50.degree. C. 
(Approximately 105.0 g of 50 percent aqueous sodium hydroxide solution was 
needed.) To the resulting sodium salt solution 23.2 g (0.25 mole) of 
epichlorohydrin was added the mixture was refluxed for two hours. At this 
point an aqueous solution of 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine trisodium salt 
[prepared by adjusting the pH of 178.0 g of a 45.88 percent aqueous 
solution of 3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
hydrochloride to 9.4-9.6] was added and the resulting solution was 
refluxed for an additional two hours. The product obtained was tested 
without purification. An aliquot of the solution was triturated under 
ethanol to yield a white hygroscopic solid that was further purified by 
recrystallization from hot ethyl alcohol and dried in a vacuum desiccator 
over P.sub.2 O.sub.5. The compound was characterized by its distinguishing 
infrared and NMR bands and by titration as a bis quaternary ammonium salt, 
but the structure was not precisely determined. 
EXAMPLE 4 
Preparation of 
N,N,N',N'-Tetramethyl-N,N'-bis(3-chloro-2-hydroxypropyl)ethylenediammonium 
Dichloride 
One hundred eighty-seven and eight tenths grams (1.0 mole) of a 61.87 
percent aqueous solution of tetramethylethylenediamine was placed into a 
1-liter, four-neck, round-bottom flask equipped with a reflux condenser, 
mechanical stirrer, thermometer and a dropping funnel and, while stirring, 
197.1 g (2.0 moles) of concentrated hydrochloric acid was introduced at 
such a rate as to keep the temperature between 40.degree. and 50.degree. 
C. When all the hydrochloric acid was introduced 185.0 g (2.0 moles) of 
epichlorohydrin was added to the tetramethylethylenediamine 
dihydrochloride solution, again taking care that the temperature did not 
exceed 50.degree. C. When this addition was completed, the temperature of 
the stirred mixture was raised to between 65.degree. and 71.degree. C. 
where it was kept for thirty minutes. The resulting solution containing 
65.66 percent of the diquaternary ammonium salt was used in subsequent 
reactions. 
EXAMPLE 5 
Reaction of 3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
with N,N,N',N'-Tetramethyl-N,N'-bis(3-chloro-2-hydroxypropyl)ethylenediamm 
onium Dichloride 
Into a 1000-ml, four-neck, round-bottom flask equipped with a mechanical 
stirrer, reflux condenser, thermometer and a dropping funnel was placed 
356.0 g of 45.88 percent aqueous 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine hydrochloride 
solution (0.5 mole) followed by enough 50 percent aqueous sodium hydroxide 
solution to adjust the pH of the mixture to 7.5-7.6. After the pH 
adjustment was made, 285.0 g (0.5 mole) of the solution described in 
Example 4 was introduced and the resulting mixture was stirred and 
refluxed for two hours. The product obtained was tested without 
purification or isolation. 
EXAMPLE 6 
Reaction of Two Moles of 
3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine with One Mole 
of 
N,N,N',N'-Tetramethyl-N,N'-bis(3-chloro-2-hydroxypropyl)ethylenediammonium 
Dichloride 
Into a 1000-ml, four-neck, round-bottom flask equipped with a mechanical 
stirrer, reflux condenser, thermometer and a dropping funnel was placed 
356.0 g of a 45.88 percent aqueous solution of 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine hydrochloride 
(0.5 mole) followed by enough 50 percent aqueous sodium hydroxide solution 
to raise the pH of the mixture to 7.5-7.6. After the pH was adjusted, 
258.0 g (0.5 mole) of the solution of Example 4 was introduced slowly and 
the resulting mixture was stirred at the reflux temperature for two hours. 
At this point an aqueous solution of 
3-(N,N-dimethylamino)-N',N'-bis-(phosphonomethyl)propylamine trisodium 
salt [prepared by adjusting the pH of 356.0 g of a 45.88 percent aqueous 
solution of 3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
hydrochloride to 9.4-9.6] was added and the resulting solution was 
refluxed for an additional two hours. The product obtained was tested 
without purification. 
EXAMPLE 7 
2-Dimethylamino-N',N'-bis(phosphonomethyl)ethylamine Hydrochloride 
Example 1 was repeated in every detail except that 441.0 g (5.0 moles) of 
N,N-dimethylethylenediamine was substituted for 
N,N-dimethylaminopropylamine. The resulting solution was used for testing 
in this form without isolation or purification. 
EXAMPLE 8 
Product of the Reaction of N,N-Dimethylcocoamine with Epichlorohydrin and 
3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine Disodium Salt 
N,N-Dimethylcocoamine hydrochloride was prepared by treating 59.8 g (0.25 
mole) of the free amine (supplied by Humko Sheffield Chemical Company as 
Kemamine T-6502D) with 24.7 g (0.25 mole) of concentrated hydrochloric 
acid while keeping the temperature below 50.degree. C. Epichlorohydrin 
(23.1 g, 0.25 mole) was added slowly between 50.degree. and 60.degree. C. 
The temperature was raised and the mixture heated at 
100.degree.-105.degree. C. for two hours. The resulting mixture was cooled 
to 50.degree. C. and a solution of 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine trisodium salt 
[prepared by adjusting the pH of 178.0 g of a 45.88 percent aqueous 
solution of 3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
hydrochloride to 9.4-9.6] was added. The resulting mixture was again 
treated at 100.degree.-105.degree. C. for two hours. A grease-like product 
was obtained. This product was tested in this form without further 
purification or isolation of the active ingredient. 
EXAMPLE 9 
Preparation of 
Poly[2-hydroxyethylene(dimethyliminio)ethylene(dimethyliminio)]methylene 
Dichloride 
Into a 2-liter, three-neck, round-bottom flask equipped with a mechanical 
stirrer, reflux condenser and a thermometer was placed 854.8 g of a 65.66 
percent aqueous solution (1.5 moles) of the diquaternary ammonium salt of 
Example 4 and 187.8 g of a 61.87 percent aqueous solution of 
tetramethylethylenediamine. The stirred mixture was refluxed for one hour 
and the resulting solution which contained 63.49 percent of the desired 
low molecular weight ionene polymer was used in reactions is this form. 
EXAMPLE 10 
Reaction of Two Moles of 
3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine with One Mole 
of 
Poly[2-hydroxyethylene(dimethyliminio)ethylene(dimethyliminio)]methylene D 
ichloride 
Into a 1-liter, three-neck, round-bottom flask equipped with a mechanical 
stirrer, reflux condenser and a thermometer was charged 356.0 g of a 45.88 
percent aqueous solution of 
3-(N,N-dimethylamino)-N',N'-bis(phosphonomethyl)propylamine hydrochloride 
(0.5 mole). The pH of this solution was adjusted to between 9.4 and 9.6 
with 50 percent aqueous sodium hydroxide solution while the temperature 
was kept below 50.degree. C. Five hundred twenty-one and three tenths 
grams of a 63.5 percent solution of the compound of Example 9 was added 
and the stirred mixture was refluxed for two hours. The product obtained 
was tested without purification. 
EXAMPLE 11 
Reaction of 2-Dimethylamino-N,N-bis(phosphonomethyl)ethylamine with 
Epichlorohydrin 
Into a 1-liter, four-neck, round-bottom flask equipped with a mechanical 
stirrer, thermometer, reflux condenser and a dropping funnel was weighed 
174.7 g of a 44.78 percent aqueous solution of Example 7 followed by 
enough 50 pecent aqueous sodium hydroxide to adjust the pH of the mixture 
to 7.5-7.6. The temperature was raised to 50.degree.-60.degree. C. and 
23.0 g of epichlorohydrin (0.25 mole) was slowly introduced. Finally, the 
mixture was heated at the reflux temperature for two hours. The resulting 
solution was tested without any further purification or isolation. 
EXAMPLE 12 
Calcium Carbonate Antiprecipitation Tests 
To evaluate the effect of the compounds of the present invention on the 
precipitation of calcium carbonate, measured volume of stock solution 
(prepared with demineralized water) of the phosphonic acids or their 
reaction product with epichlorohydrin were added to 100-ml portions of a 
calcium hydroxide solution (0.40 g Ca(OH).sub.2 per liter). Then 100 ml of 
a sodium bicarbonate solution (0.50 g NaHCO.sub.3 per liter) was added to 
each portion of calcium hydroxide solution. The pH of each portion was 
adjusted to 9.00 (.+-.0.05). The test solutions were then agitated on a 
rotary shaker for approximately 18 hours at a temperature of 25.degree. C. 
At the end of this time insoluble material was removed by filtration with 
Whatman No. 4 filter paper and the calcium ion concentration in the 
filtrate was determined by titration with a standard ethylenediamine 
tetraacetic acid solution. The percent inhibition (Table 1) was calculated 
by comparing the test solution values with two controls included in every 
test series. The compounds tested were as follows: 
A. The reaction product of Example 1. 
B. The reaction product of Example 2. 
C. The reaction product of Example 3. 
D. The reaction product of Example 5. 
E. The reaction product of Example 6. 
F. The reaction product of Example 7. 
G. The reaction product of Example 8. 
H. The reaction product of Example 10. 
I. The reaction product of Example 11. 
EXAMPLE 13 
Corrosion Inhibiting Properties of the Compounds of this Invention 
This example illustrates the corrosion-inhibiting properties of the 
compounds of the present invention. 
The test apparatus included a sump, a flow circuit, a circulating pump and 
a heater. The heat coupons were 1010 mild steel. The test fluid was 
Memphis tap water with the pH adjusted to 7.5 and the temperature was 
maintained at 50.degree. C..+-.2.degree. C. 
The test fluid containing various concentrations of the compositions 
described herein was circulated continuously through the system containing 
the test coupons for a period of three days. At the end of this period, 
the coupons were removed, cleaned and weighed. The corrosion rates were 
calculated in milligrams per square decimeter per day (MDD). 
The compounds tested are those described in Example 12 from A through I. 
TABLE 1. 
______________________________________ 
Inhibition of Calcium Carbonate Precipitation at pH 9. 
Con- 
cen- 
tration 
Parts PRODUCT TESTED 
per A B C D E F G H I 
Million 
PERCENT INHIBITION 
______________________________________ 
1.0 0 16.9 0 31.0 5.9 6.2 5.6 32.7 20.4 
2.0 0 47.4 0 32.1 9.0 17.8 16.8 23.0 28.9 
3.0 4.2 70.4 2.0 67.9 20.7 32.3 21.2 27.0 44.3 
4.0 41.6 76.0 11.3 82.4 28.5 35.3 31.3 33.4 -- 
5.0 50.9 82.4 47.1 87.2 30.1 49.5 28.0 44.4 26.4 
6.0 54.5 90.2 0 88.3 41.0 55.6 34.0 48.8 22.1 
7.0 64.1 90.5 4.5 93.1 50.4 65.2 33.2 50.4 57.0 
8.0 60.6 92.9 25.6 94.8 52.0 69.6 35.3 56.8 82.1 
9.0 69.4 93.2 28.7 95.9 57.4 77.7 47.9 52.5 77.0 
10.0 67.5 93.6 36.9 92.4 60.0 78.6 43.8 55.4 87.7 
Con- 
trol 2.05 2.05 1.21 1.45 1.21 0.71 0.89 0.89 2.98 
Ca.sup.++ 
6.14 6.14 6.09 4.35 6.09 6.00 5.71 5.71 5.33 
blank 
______________________________________ 
TABLE 2. 
__________________________________________________________________________ 
Corrosion Inhibition with the Compounds of this Invention 
Concen- CORROSION RATE 
tration Copper Inhi- 
Corrosion 
Parts per 
Initial 
Final 
Sump 1 
Sump 2 
Couple 
Average 
bition 
Inhibitor 
Million 
pH pH Miligrams per decimeter per day 
Percent 
__________________________________________________________________________ 
A 50 7.5 7.2 
1.33 
0.18 
3.01 
1.51 99.4 
100 7.5 7.5 
0.89 
1.77 
1.06 
1.24 99.5 
200 7.5 7.7 
1.15 
1.33 
3.90 
2.13 99.2 
B 50 7.5 7.8 
0.35 
0.18 
0.98 
0.50 99.8 
100 7.5 7.9 
0.53 
0.62 
1.24 
0.80 99.7 
200 7.5 7.9 
0.62 
0.09 
1.86 
0.86 99.7 
C 50 7.5 8.1 
8.51 
5.85 
5.59 
6.65 97.5 
100 7.5 8.2 
4.61 
3.46 
4.43 
4.17 98.4 
150 7.5 8.1 
5.41 
6.38 
7.27 
6.35 97.6 
D 50 7.5 8.3 
2.04 
3.01 
2.04 
2.36 99.1 
100 7.5 8.2 
1.42 
1.15 
4.08 
2.22 99.2 
150 7.5 8.1 
2.66 
2.57 
6.03 
3.75 98.6 
E 50 7.5 7.6 
12.06 
15.87 
4.34 
10.76 
95.9 
100 7.5 7.9 
3.19 
2.48 
3.37 
3.01 98.9 
150 7.5 7.9 
3.46 
3.90 
5.05 
4.14 98.4 
F 50 7.5 8.0 
12.94 
53.37 
40.08 
35.46 
86.6 
100 7.5 7.9 
1.24 
1.51 
1.95 
1.57 99.4 
150 7.5 7.9 
1.15 
1.06 
0.98 
1.06 99.6 
G 50 7.5 8.1 
58.60 
33.51 
80.14 
57.42 
78.3 
100 7.5 8.0 
8.69 
8.78 
22.43 
13.30 
95.0 
150 7.5 8.0 
72.43 
81.83 
134.31 
96.19 
63.7 
H 50 7.5 7.5 
4.00 
5.05 
6.12 
5.06 98.1 
100 7.5 8.0 
6.21 
4.96 
5.41 
5.53 97.9 
150 7.5 8.0 
3.37 
6.03 
17.82 
9.07 96.6 
I 50 7.5 8.4 
2.30 
3.81 
2.66 
2.92 98.9 
100 7.5 8.1 
1.95 
2.30 
3.99 
2.75 99.0 
150 7.5 8.0 
2.04 
2.04 
5.38 
3.15 98.8 
Control 
0 7.5 7.8 
193.0 
258.0 
356.0 
269.0 
0 
Water Memphis Tap Water 
Temperature 
50.degree. C. 
Time Three days 
__________________________________________________________________________ 
EXAMPLE 14 
Reaction of 3-(N,N-Dimethylamino)-N',N'-bis(phosphonomethyl)propylamine 
with Epichlorohydrin 
A solution was prepared by mixing 1170 g (10.0 moles) of phosphorous acid 
(70 percent in water) and 806 g (8.4 moles) of hydrochloric acid (38 
percent in water). To this solution was added 408 g (4.0 moles) of 
3-dimethylaminopropylamine while cooling. The reaction mixture was then 
heated to 110.degree.-115.degree. C. and 681 g (8.4 moles) of formaldehyde 
(37 percent in water) was added dropwise. The mixture was then heated at 
reflux for three hours and excess reagents were removed at the end of the 
heating cycle by distilling 533 g from the mixture. 
An aliquot, which weighed 1266 g, was treated with 989 g of 50 percent 
sodium hydroxide solution to a pH of 10.5 while the temperature was kept 
below 40.degree. C. The mixture was cloudy and viscous so 200 g of water 
was added to obtain a clear solution. 
One-tenth of a mole of the trisodium salt of 
3-(N,N-dimethylamino)-N','-bis(phosphonomethyl)propylamine was contained 
in 122.1 g of the above solution. This amount was mixed with 4.8 g (0.05 
mole) of hydrochloric acid (38 percent in water) and 4.6 g (0.05 mole) of 
epichlorohydrin. The mixture was agitated at room temperature for sixteen 
hours and then refluxed for two hours. A clear solution was obtained. 
The product obtained was tested as a calcium carbonate antiprecipitant 
using the method described in Example 12 except that the pH was not 
adjusted to pH 9. At 3 parts per million, 85 percent inhibition of 
precipitation was obtained. 
While particular embodiments of the invention have been described, it will 
be understood, of course, that the invention is not limited thereto since 
many modifications may be made, and it is, therefore, contemplated to 
cover by the appended claims any such modifications as fall within the 
true spirit and scope of the invention.