This invention relates to compounds characterized by the presence of N-methyl, or substituted methyl, phosphonic acid and N-hydroxy-propylenesulfonic acid groups. These compounds contain at least one or more of each group and are bonded to the same or different amino groups. They are derived by reacting an amine with both (1) an epihalohydrin-bisulfite addition product and (2) with a carbonyl compound, such as formaldehyde, and phosphorous acid or its equivalent. They have a wide variety of uses, for example as scale and corrosion inhibitors, iron oxide removers, chelating agents, etc.

The compounds of this invention may be presented by the following idealized 
formula 
##STR1## 
where N is an amino moiety and n and m are at least 1, such as 1-5, for 
example from 1-3, but preferably 1. 
In the case of a monoamine, n and m are 1. In the case of polyamine n and m 
can vary widely depending on the number of amino groups. Theoretically, 
the sum of n+m can be equal to the number of replaced amino hydrogens. In 
general, the sulfonic acid groups are 1-2 or more and the phosphonic acid 
groups are 1-5 or more. 
Any amine capable of reacting with an epihalohydrin-bisulfate reaction 
product (HBS) can be employed, for example any amine having at least one 
primary amino group. Where the amine has more than one primary amino 
group, the number of sulfonic acid groups in the product will depend on 
the moles of HBS employed, for example 
##STR2## 
Theoretically, some or all of the remaining nitrogen-bonded hydrogens can 
be converted to the methyl phosphonic acid depending on the stoichiometry 
of the reactants. 
Any amino group having a reactive N-hydrogen group which is capable of 
reacting with a carbonyl compound and phosphorous acid or equivalent can 
be reacted to yield the compounds of this invention. 
The aminomethyl phosphonic acids of this invention and their salts may be 
prepared by various methods. One method comprises reacting (1) an amine 
having reactive hydrogens attached to a nitrogen atom, (2) a carbonyl 
compound such as an aldehyde or a ketone and (3) phosphorous acid, usually 
in the form of the dialkyl phosphite. The free N-aminomethyl phosphonic 
acids and their salts may be prepared by hydrolysis of the phosphonic 
ester under acid conditions such as with strong mineral acid such as HCl 
and the like. 
These may be illustrated by the following reaction: 
##STR3## 
In the above equation X and Y are hydrogen or a substituted group such as 
an alkyl or aryl group, etc. 
Phosphonic esters are converted to phosphonic acids or salts thereof 
according to the following reaction: 
##STR4## 
and other corresponding reactions. 
Salts of these can also be prepared, for example salts containing metal, 
ammonium, amine, etc. groups such as sodium, potassium, triethanolamine, 
diethanolamine. 
A second method comprises reacting (1) an amine, (2) a carbonyl compound 
such as aldehyde or a ketone and (3) phosphorous acid preferably in 
presence of a strong mineral acid such as hydrochloric acid. This method 
yields the aminomethyl phosphonic acids directly. 
This may be illustrated by the following reaction: 
##STR5## 
The general synthetic procedure involves three steps: (1) the reaction of 
an epihalohydrin with a bisulfite salt to form HBS, (2) reaction of a 
primary amine with HBS to form a .gamma.-amino sulfonic acid and (3) 
reaction of this molecule with formaldehyde and phosphorous acid. 
These products may be illustrated by the general formula 
##STR6## 
The reaction sequence utilized is as follows: 
##STR7## 
This reaction is applicable to a wide range of amines; thus R can be alkyl 
such as CH.sub.3, C.sub.2 H.sub.5, C.sub.3 H.sub.7, C.sub.4 H.sub.9, 
C.sub.6 H.sub.13, C.sub.8 H.sub.17, C.sub.12 H.sub.25, C.sub.18 H.sub.37, 
etc., straight chained or branched such as isopropyl, 2-ethyl hexyl, etc., 
cyclic aliphatic groups such as cyclopentyl, cyclohexyl. 
Other amines which can be reacted include polyamines such as polyalkylene 
polyamines for example of the formula 
##STR8## 
where A is alkylene for example having 2-10 carbons or more and n=1 to 10 
or more, for example diamines such as ethylene diamine, propylene diamine, 
diethylene triamine, N-substituted 1,3-propylene diamines, etc. 
Amines suitable for this process include the following: 
n-Butylamine 
2-ethyl hexyl amine 
Monoisopropanolamine 
Hexylamine 
Heptylamine 
Octylamine 
Decylamine 
Furfurylamine 
Dodecylamine 
Monoethanolamine 
n-Amylamine 
Sec-amylamine 
2-amino-4-methylpentane 
4-amino-2-butanol 
5-isopropylamino-1-pentanol 
Also, high molecular weight aliphatic amines known as Armeen 10, Armeen 
16D, Armeen HTD, Armeen 18D, and Armeen CD can be used (RNH.sub.2). 
Other amines include: 
2-amino-2-methyl propanol 
2-amino-2-methyl-1,3-propanediol 
2-amino-2-ethyl-1,3-propanediol 
3-amino-2-methyl-propanol 
2-amino-1-butanol 
3-amino-2,2-dimethyl-1-propanol 
2-amino-2,3-dimethyl-1-propanol 
2,2-diethyl-2-amino ethanol 
2,2-dimethyl-2-amino ethanol 
3-amino-1,2-butanediol 
4-amino-1,2-butanediol 
2-amino-1,3-butanediol 
4-amino-1,3-butanediol 
2-amino-1,4-butanediol 
3-amino-1,4-butanediol 
1-amino-2,3-butanediol 
Amines having ring structures include cyclohexylamine, and various 
comparable amines with alkyl substituents in the ring. 
A wide variety of polyamines also can be employed. These include the 
polyalkylene polyamines such as of the formula: 
##STR9## 
in which R" is hydrogen, alkyl, cycloalkyl, aryl, or aralkyl and R' is a 
divalent radical such as: 
##STR10## 
Examples of suitable polyamines include: 
Ethylenediamine 
Diethylenetriamine 
Triethylenetetramine 
Tetraethylenepentamine 
Propylenediamine 
Dipropylenetriamine 
Tripropylenetetramine 
Butylenediamine 
Aminoethylpropylenediamine 
Aminoethylbutylenediamine 
##STR11## 
Other polyamines in which the nitrogen atoms are separated by a carbon atom 
chain having 4 or more carbon atoms include the following: 
Tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, etc. 
If desired, one can prepare a variety of reactants having two or more amino 
groups and at least one hydroxyl group. One may use modifications of 
procedures or the procedures themselves as described in U.S. Pat. Nos. 
2,046,720, dated July 7, 1936, to Bottoms; 2,048,990 dated July 28, 1936, 
to Britton et al.; 2,447,821 dated Aug. 24, 1949, to Sankus; and 1,985,885 
dated Jan. 1, 1935, to Bottoms. Examples include the following: 
##STR12## 
Other suitable amines are exemplified by ethylene-bisoxypropylamine, 
##STR13## 
Another example of polyamines which may be employed as a reactant is the 
kind described as "Duomeens." 
Duomeen is a trademark designation for certain diamines. Duomeen has the 
following general formula: 
##STR14## 
R is an alkyl group derived from a fatty acid or from the mixed fatty 
acids as obtained from certain oils. The specific Duomeen and the source 
of the radical R are as follows: 
Duomeen 12, R=lauric 
Duomeen C, R=Coconut oil fatty acid 
Similarly, a commparable diamine, presumably obtained from Rosin Amine D 
and acrylonitrile, can be prepared. The structure of Rosin Amine D is as 
follows: 
##STR15## 
Polyamines from monoamines and cyclic imines, such as ethylene imine. 
##STR16## 
It is to be noted that all the above examples show high molal groups, i.e., 
8 carbon atoms or more. The same derivatives in which methyl, ethyl, 
propyl, butyl, amyl, hexyl groups, or the like, appear instead of octyl, 
decyl, etc., are equally satisfactory. 
Cyclic amidines, such as imidazolines and tetrahydropyrimidines, having an 
amino side chain can be reacted, for example: 
##STR17## 
Tetrahydropyrimidines from monocarboxylic acids and trimethylenepolyamines. 
##STR18## 
(1) The reaction between the epihalohydrin and the bisulfite salt is facile 
and takes place at 20.degree. to 100.degree. C. to form HBS. (2) The 
reaction between amines and HBS is very facile and occurs quite readily at 
temperatures from 30.degree.-70.degree. in a solvent such as methanol. 
Step (3) takes place at low pH and is most conveniently performed in 
aqueous HCl. Thus the amino sulfonate and phosphorous acid are heated in 
hydrochloric acid during the addition of formaldehyde usually at reflux. 
The following examples illustrate the procedures. All temperatures are 
.degree.C.

EXAMPLE 1 
Preparation of 3-chloro-2-hydroxypropyl-sulfonic acid sodium salt 
To a solution of sodium bisulfite (10 moles) in water (2500 ml) held at 
80.degree.-90.degree. C. was added epichlorohydrin (10 moles) during 45 
mins. Upon completion of the addition the mixture was heated at reflux for 
1 hour. Upon cooling crystalline 3-chloro-2-hydroxypropyl-sulfonic acid 
sodium salt separated mp 253.degree.-6.degree. (decomp). 
EXAMPLE 2 
The chloropropylsulfonic acid of Example 1 (98 g; 0.5 mole) in water (130 
g) was mixed with a 70% aqueous ethylamine solution (32 g; 0.5 mole) and 
heated at reflux for 1 hour. Evaporation of the water yield crude 
ethylaminosulfonic acid. Crystallization from methanol gave pure sulfonic 
acid of structure 
##STR19## 
Anal. Found N, 6.95; S, 17.40; Calculated N, 7.65; S, 17.49. 
EXAMPLE 3 
The propylsulfonic acid of Example 1 (0.5 mole) in water (229 g) was heated 
with butylamine (36.5 g; 0.5 mole) for 1 hour at reflux. The crude 
aminosulfonic acid was obtained by evaporation of the water. 
Recrystallization from methanol yielded pure aminosulfonic acid mp 
143.degree.-5.degree. 
##STR20## 
Anal. Found N, 6.08; S, 15.30; Calculated N, 6.63; S, 15.17. 
EXAMPLE 4 
In the manner of Example 2 n-hexylamine was reacted with 
3-chloro-2-hydroxypropylsulfonic acid to yield 
##STR21## 
Anal. Found N, 5.58; S, 14.38; Calculated N, 5.85; S, 13.39. 
EXAMPLE 5 
In the manner of Example 2 cyclohexylamine was reacted with 
3-chloro-2-hydroxypropylsulfonic acid to yield the N-cyclohexyl compound 
mp 166.degree.-170.degree. 
##STR22## 
Anal. Found N, 5.85; S, 13.63; Calculated N, 5.90; S, 13.50. 
EXAMPLE 6 
In the manner of Example 2 t-octylamine was reacted with 
3-chloro-2-hydroxypropylsulfonic acid to yield 
##STR23## 
Anal. Found S, 11.73; Calculated S, 11.85. 
EXAMPLE 7 
To a solution of ethylene diamine (30 g; 0.5 mole) in water (100 ml) was 
added 3-chloro-2-hydroxypropylsulfonic acid (98 g; 10.5 mole) in water 
(200 ml) and the mixture heated under reflux for 1 hour. Evaporation of 
the solvent yielded the aminopropyl sulfonic acid of the formula 
##STR24## 
Analysis: Found N, 11.16; S, 14.81; Calculated N, 11.41; S, 16.2. 
EXAMPLE 8 
The procedure of Example 7 was repeated using a mole ratio of 1:2 to yield 
as the product 
##STR25## 
EXAMPLE 9 
By the procedure of Example 7 diethylene triamine (0.5 mole) was reacted 
with the propylsulfonic acid (0.5 mole) of Example 1 to yield 
##STR26## 
EXAMPLE 10 
By the procedure of Example 7 diethylene triamine (0.25 mole) was reacted 
with the propylsulfonic acid (0.5 mole) of Example 1 to yield 
##STR27## 
The following examples illustrate the preparation of amino-methylene 
phosphoric acids from the aminosulfonic acid derivatives of Examples 2-10. 
EXAMPLE 11 
The aminosulfonic acid of Example 2 (0.2 mole) was dissolved in 18% 
hydrochloric acid (60 ml) and phosphorus acid (16.4 g; 0.2 mole) added. 
After heating to gentle reflux (103.degree.) 37% formaldehyde (25 g; 0.3 
mole) was added during 1 hour. The reaction was complete after heating at 
reflux for 4 hours. Evaporation of the aqueous acid and crystallization 
yielded the aminosulfonic phosphonic acid of the formula: 
##STR28## 
Anal. Found N, 5.10; P, 11.30; Calculated N, 5.05; P, 11.19. 
EXAMPLE 12 
The aminosulfonic acid of Example 3 (0.15 mole) and phosphorous acid (12.3 
g; 0.15 mole) dissolved in 18% hydrochloric acid (50 ml) and heated to 
gentle reflux. To this solution was added 37% formaldehyde (19 g) during 
45 mins. and the mixture heated at reflux for 3 hours to complete 
reaction. Evaporation of the aqueous acid and crystallization yielded the 
aminosulfonic phosphonic acid of the following formula: 
##STR29## 
The product was characterized nmr and the following analysis: 
Found N, 4.13; P, 10.07; Calculated N, 4.59; P, 10.16. 
EXAMPLE 13 
The aminosulfonic acid derived from n hexylamine (Example 4) (0.2 mole) was 
converted into the corresponding sulfonic-phosphonic acid by the procedure 
of Example 11. 
The structure was shown by nmr to be: 
##STR30## 
Analysis: Found N, 4.33; P, 9.07; Calculated N, 4.19; P, 9.28. 
EXAMPLE 14 
The aminosulfonic acid from cyclohexylamine (Example 5) was converted by 
the procedure of Example 11 to the corresponding phosphonic acid. 
Analysis: Found N, 4.10; P, 9.33; Calcuated N, 4.22; P, 9.37. 
EXAMPLE 15 
The aminosulfonic acid of Example 6 derived from t octylamine was converted 
into the corresponding phosphonic acid by the method of Example 11. The 
structure of the product by nmr was shown to be 
##STR31## 
Analysis: Found N, 3.07; P, 8.27; Calculated: N, 3.88; P, 8.59. 
EXAMPLE 16 
The mono sulfonic acid derived from ethylene diamine (Example 7) was 
reacted with three equivalents of phosphorous acid and formaldehyde by the 
procedure of Example 11. 
The product is represented by the formula 
##STR32## 
Analysis: Found P, 19.47; Calculated P, 19.40. 
EXAMPLE 17 
The disulfonic acid derived from ethylene diamine (Example 8) was reacted 
under the conditions of Example 11 with two equivalents of phosphorous 
acid and formaldehyde to yield the sulfonic/phosphonic acid below as the 
major product: 
##STR33## 
Analysis: Found N, 5.45; S, 11.43; P, 10.4; Calculated N, 5.34; S, 12.21; 
P, 11.8. 
EXAMPLE 18 
The monosulfonic acid of Example 9 was reacted with four equivalents of 
formaldehyde and phosphorous acid according to the procedure of Example 12 
to yield the following product 
##STR34## 
Analysis: Found P, 19.60; Calculated P, 20.10. 
EXAMPLE 19 
The disulfonic acid of Example 10 was reacted with three equivalents of 
phosphorous acid and formaldehyde by the procedure of Example 11. The 
product is a mixture, the major component of which is shown as follows: 
##STR35## 
Analysis: Found P, 15.0; S, 10.09; Calculated: P, 14.1; S, 9.68. 
USE AS SCALE INHIBITOR 
Most commercial water contains alkaline earth metal cations, such as 
calcium, barium, magnesium, etc., and anions such as bicarbonate, 
carbonate, sulfate, oxalate, phosphate, silicate, fluoride, etc. When 
combinations of these anions and cations are present in concentrations 
which exceed the solubility of their reaction products, precipitates form 
until their product solubility concentrations are no longer exceeded. For 
example, when the concentrations of calcium ion and carbonate ion exceed 
the solubility of the calcium carbonate reaction product, a solid phase of 
calcium carbonate will form as a precipitate. 
Solubility product concentrations are exceeded for various reasons, such as 
evaporation of the water phase, change in pH, pressure or temperature, and 
the introduction of additional ions which can form insoluble compounds 
with the ions already present in the solution. 
As these reaction products precipitate on the surfaces of the 
water-carrying system, they form scale. The scale prevents effective heat 
transfer, interferes with fluid flow, facilitates corrosive processes, and 
harbors bacteria. Scale is an expensive problem in many industrial water 
systems, causing delays and shutdowns for cleaning and removal. 
Scale-forming compounds can be prevented from precipitating by 
inactivating their cations with chelating of sequestering agents, so that 
the solubility of their reaction products is not exceeded. Generally, this 
approach requires many times of much chelating or sequestering agent as 
cation present, and the use of large amounts of treating agent is seldom 
desirable or economical. 
More than twenty-five years ago it was discovered that certain inorganic 
polyphosphates would prevent such precipitation when added in amounts far 
less than the concentrations needed for sequestering or chelating. See, 
for example, Hatch and Rice, "Industrial Engineering Chemistry," vol. 31, 
p. 51, at 53; Reitemeier and Buchrer, "Journal of Physical Chemistry," 
vol. 44, No. 5, p. 535 at 536 (May 1940); Fink and Richardson U.S. Pat. 
No. 2,358,222; and Hatch U.S. Pat. No. 2,539,305. When a precipitation 
inhibitor is present in a potentially scale-forming system at a markedly 
lower concentration than that required for sequestering the scale forming 
cation, it is said to be present in "threshold" amounts. Generally, 
sequestering takes place at a weight ratio of threshold active compound to 
scale-forming cation component of greater than about ten to one, and 
threshold inhibition generally takes place at a weight ratio of threshold 
active compound to scale-forming cation component of less than about 0.5 
to 1. 
The "threshold" concentration range can be demonstrated in the following 
manner. When a typical scale-forming solution containing the cation of a 
relatively insoluble compound is added to a solution containing the anion 
of the relatively insoluble compound and a very small amount of a 
threshold active inhibitor, the relatively insoluble compound will not 
precipitate even when its normal equilibrium concentration has been 
exceeded. If more of the threshold active compound is added, a 
concentration is reached where turbidity or a precipitate of uncertain 
composition results. As still more of the threshold active compound is 
added, the solution again becomes clear. This is due to the fact that 
threshold active compounds in high concentrations also act as sequestering 
agents, although sequestering agents are not necessarily "threshold" 
compounds. Thus, there is an intermediate zone between the high 
concentrations at which they act as threshold inhibitors. Therefore, one 
could also define "threshold" concentrations as all concentrations of 
threshold active compounds below that concentration at which this turbid 
zone or precipitate is formed. Generally the threshold active compound 
will be used in a weight ratio of the compound to the cation component of 
the scale-forming salts which does not exceed about 1. 
The polyphosphates are generally effective threshold inhibitors for many 
scale-forming compounds at temperatures below 100.degree. F. But after 
prolonged periods at higher temperatures, they lose some of their 
effectiveness. Moreover, in an acid solution, they revert to ineffective 
or less effective compounds. 
A compound that has sequestering powers does not predictably have threshold 
inhibiting properties. For example, ethylenediamine tetracetic acid salts 
are powerful sequesterants but have no threshold activities. 
We have now discovered a process for inhibiting scale such as calcium, 
barium and magnesium carbonate, sulfate, silicate, etc., scale which 
comprises employing threshold amounts of the compositions of this 
invention. 
In general it is preferred that at least 50% but preferably at least 80% of 
the nitrogen-bonded hydrogens of the polyamine be replaced by sulfonate or 
phosphonate groups. 
Scale formation from aqueous solutions containing an oxide variety of scale 
forming compounds, such as calcium, barium and magnesium carbonate, 
sulfate, silicate, oxalates, phosphates, hydroxides, fluorides and the 
like are inhibited by the use of threshold amounts of the compositions of 
this invention which are effective in small amounts, such as less than 100 
ppm and are preferably used in concentrations of less than 25 ppm. 
The compounds of the present invention (e.g., the acid form of the 
compounds) may be readily converted into the corresponding alkali metal, 
ammonium or alkaline earth metal salts by replacing at least half of the 
hydrogen ions in the phosphonic acid group with the appropriate ions, such 
as the potassium ion or ammonium or with alkaline earth metal ions which 
may be converted into the corresponding sodium salt by the addition of 
sodium hydroxide. If the pH of the amine compound is adjusted to 7.0 by 
the addition of caustic soda, about one half of the --OH radicals on the 
phosphorous atoms will be converted into the sodium salt form. 
The scale inhibitors of the present invention illustrate improved 
inhibiting effect at high temperatures when compared to prior art 
compounds. The compounds of the present invention will inhibit the 
deposition of scale-forming alkaline earth metal compounds on a surface in 
contact with aqueous solution of the alkaline earth metal compounds over a 
wide temperature range. Generally, the temperatures of the aqueous 
solution will be at least 40.degree. F., although significantly lower 
temperatures will often be encountered. The preferred temperature range 
for inhibition of scale deposition is from about 130.degree. to about 
350.degree. F. The aqueous solutions or brines requiring treatment 
generally contain about 50 ppm to about 50,000 ppm of scale-forming salts. 
The compounds of the present invention effectively inhibit scale formation 
when present in an amount of from 0.1 to about 100 ppm, and preferably 0.2 
to 25 ppm wherein the amounts of the inhibitor are based upon the total 
aqueous system. There does not appear to be a concentration below which 
the compounds of the present invention are totally ineffective. A very 
small amount of the scale inhibitor is effective to a correspondingly 
limited degree, and the threshold effect is obtained with less than 0.1 
ppm. There is no reason to believe that this is the minimum effective 
concentration. The scale inhibitors of the present invention are effective 
in both brine, such as sea water, and acid solutions. 
Calcium Scale Inhibition Test 
The procedure utilized to determine the effectiveness of scale inhibitors 
in regard to calcium scale is as follows: 
Several 50 ml. samples of a 0.04 sodium bicarbonate solution are placed in 
100 ml. bottles. To these solutions is added the inhibitor in various 
known concentrations. 50 ml. samples of a 0.02 M CaCl.sub.2 solution are 
then added. 
A total hardness determination is then made on the 50--50 mixture utilizing 
the well known Schwarzenbach titration. The samples are placed in a water 
bath and heated at 180.degree. F. 10 ml. samples are taken from each 
bottle at 2 and 4 hour periods. These samples are filtered through 
millipore filters and the total hardness of the filtrates are determined 
by titration. 
##EQU1## 
______________________________________ 
Calcium Scale Inhibition 
Compound Concentration % Inhibition 
______________________________________ 
Example 7 
50 ppm 50% 
Example 8 
50 ppm 45% 
Example 9 
50 ppm 45% 
Example 10 
25 ppm 45% 
Example 16 
10 ppm 91% 
Example 16 
25 ppm 100% 
Example 17 
15 ppm 72% 
Example 17 
25 ppm 96% 
Example 17 
50 ppm 100% 
Example 19 
25 ppm 86% 
Example 19 
50 ppm 100% 
______________________________________ 
Other uses include the following: 
Use as corrosion inhibitors 
Use as iron chelating agents, particularly to dissolve iron oxide deposits, 
in cooling water towers, etc.