Note: Descriptions are shown in the official language in which they were submitted.
, A CA 02249171 1998-09-30
AND CoMposITIoN FOR INXIBITING CORROSION
The invention provides a method for inhibi~ing corrosion on metal
surfaces and is characterized by the use of specific aminoamides
as corrosion inhibitors. Compositions providing corrosion
inhibition are provided. The method is applicable to corrosion
inhibition of metal surfaces in general and is applied in
geothermal wells, refineries, heat transfer fluids, lubricating
fluids, lubricants, coating adhesives, fire retardants, plastics,
glass and the like and is particularly applicable to prevention
o~ corrosion in gas or oil wells. A special characteristic of
the invention is the provision o~ corrosion inhibition under high
temperature conditiPns with or without high pressure conditions.
Backqround of the Invention
There is an increasing demand for corrosion inhibitor materials
that can withstand high temperatures. This i8 because systems
are becnr';ng more efficient, more complex, or are found in
increasingly hostile environments such as high temperature and
high pressure conditions.
Se~eral o* these systems require high temperature corrosion
inhibition chemicals. Various drilling operations and the
production of gas, petroleum, and geothermal deep, hot wells can
experience temperatures above 150~C, sometimes above 290OC.
Certain refinery operations experience the need for inhibitors
tlo perform at about 150~C to 350~C to control corrosion in the
overhead equipment as well as 200~ to 400~C in specialized
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,
cracking units and distillation towers. Heat transfer fluids
used in process heating and cooling, ventilation and air-
conditioning plants, and stationary engines such as gas-line
tr~n~i~sion compressors require ~her~l stability up to about
350~C; these require corrosion inhibitors to ;n;~;ze corrosion
and fouling. Various lubricants are now used in high temperature
situations, such as in the case o~ engines and turbines using
both petroleum-based as well as synthetic stocks. Numerous
coatings, adhesives, thermosetting resins and fire-~retardant
compositions also require high te~perature stability.
.
The corrosion inhibitors of interest are film-forming materials.
These can be used at low levels and be applied in a variety of
ways. These corrosion inhibitors have an oleopilic portion to
serve as a barrier to oxygen, water and other corrosive entities,
and a polar portion to bond with the metallic sur~aces. The
polar portions tend to be amines, and the bon~;ng is between the
nitrogen lone electron pair and the vacant d-orbitals in the
metallic mol~cl7l ~r array. The oleophilic groups are usually
fatty hydrocarbon ~-h;~; n~ between c~ and C30. Originally, fatty
amines were used as corrosion inhibitors.
Many r ine~ are known to be thermally unstable at high
temperature. They can decompose to yield ammonia, or other
fragmented amines such as methylamine, and olefins. These
olefins can react further under degradation conditions to produce
insol7lble aromatics and polymers. This degradation causes the
corrosion inhibition effect to decrease at high temperature.
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DE-Offenlegungsschrift 30 29 790 teaches a method for corrosion
inhibiting in a high temperature and high pressure gas well. In
this method a fatty amine having a high molecular weight or an
N-alkyl-1,3-propane diamine in which the alkyl contains 16 to 30
carbon atoms is injected into said well and forms a protective
layer on the metal equipment.
As is shown by the inventor of this application (product of
Example 3 and its use) the most preferred corrosion inhibitor o~
the above publication proved insufficiently effective at a
temperature o~ about 290~C. Obviously there is a significant
~ec~rosition of the corrosi~n inhibitor at such high
temperatures. In a further method, a combination of one of the
above mentioned ~;nP~ with a dialkylsulfide is used - see U.S.
Patent No. 4, 350, 600. Besides the limited stability of the
amine, such a combination is disadvantageous because o~ the
employment of an odorous and toxic compound.
According to u.S. Patent No. 3,959,158 corrosion of metal
sur~aces in oil and gas wells can be inhibited at high
temperature, that means, at about 149 to 288~C, by introduci~g
into such wells a corrosion inhibiting composition comprising a
primary fatty amine where the carbon atom is Cg to C~, a
trimerized unsaturated fatty acid and an alkylarylsulfonic acid.
Amide ~ormation is discouraged. The corrosion inhibiting
effectiveness is regarded as insufficient at a temperature of
above 290~C, a temperature which cannot be excluded in deep
wells, especially in gas wells.
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It is known that 2-substituted fatty acids, like nonylphenoxy-
acetic acid and polyamines, like alkylene rl;;~m; nes or
imidazolines derived therefrom, or isophorone diamine, can be
used as corrosion inhibitors alone. According to U.S. Patent ~o.
3,775,320 a combinatiQn of both compounds in the form o~ a salt
leads to a synergistically improved corrosion inhibiting e~fect.
In DE-Offenlegungsschrift 26 22 066, an alkyl- or alkenyl
succinic acid can be used for salt formation with a polyamine.
It has been found by the inventor of the present application and
other persons that inhibitors based on a 1,2- or 1,3-
alkylenediamine or corresponding polyalkylene polyamines are of
limited thermal stability. Although such compounds are well
effective at low temperature, they ~ail at high temperature,
e.g., at above 290~C.
As systems began to reguire increased thermal stability, fatty
amides were used as corrosion inhibitors. These were formed from
fatty acids and amines, or fatty amines with carboxylic acids.
Many o~ these materials, however, have poor solubility in
hydrocarbon and aromatic solvents, making them difficult to
apply.
When fatty acids were treated with some polyamines, the resulting
imidazoline or tetrahydropyrimidine structures did provide good
corrosion inhibition at lower temperatures. ~owever, much degra-
dation was produced when the system being treated experienced
high temperatures. This caused decreased per~ormance, increased
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gunking/fouling, and in some ca~es, accelerated corrosion.
Additionally, these materials are easily subject to hydrolysis.
According to U.S. Patent No. 3,412,024 corrosion of iron or steel
tubing and other materials formed ~rom ~errous metals which come
into contact with corrosive sweet and sour crude oils, especially
those con~Ain;ng corrosive brines, can be inhibited or ~n; ;7ed
by treating said metals with a corrosion inhibiting composition
contA;n;ng a salt of (i) alkylbenzene sulfonic acids and partial
amides or (ii) monomeric, dimeric or trimeric higher fatty acids.
Said partial amides are aminoamides made from monomeric, dimeric
or trimeric fatty acids and polyalkylene polyamines having 3 -
amino groups. The preferred diethylenetriamine and
dipropylene-1,2-triamine based amides are known to be easily
converted to less stable imidazolines. It has been found by the
inventor of this application that the thermal stability of said
amides is too low ~or use as a corrosion inhibitor in oil and gas
wells at high temperature, e.g., at 290~C to 340~C. A further
disadvantage is the presence of a sulfur con~A;n;ng compound in
the inhibitor composition.
According to ~P 04/202 396 A (Derwent Abstract 92-29558t36]WPIDS)
lubricant with improved wire-drawing rate and increased life-
time of dies contains a carboxylic amide type wax obtained by
reacting a higher aliphatic monocarboxylic acid o~ its mixture
with a polybasic acid with a diamine, e.g., isophorone ~;Am;ne~
m-xylylene diamine or a ~ Cz- to C6- alkylene diamine. As the
ratio of diamines to monocarboxylic acid may be 1-2 to 2, the
s
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reaction product includes aminoamides. There i5 no indication
in said Japanese patent publication of any corrosion inhibiting
effect nor any indication whereupon specific aminoamides are much
more thermally stable than others and there~ore could be applied
at high t~mr~ature. It has been found by the inventor of the
prese~t application that the thermal stability of most of the
mentioned aminoamides is low, except tha.~t of monoamides based on
a higher fatty acid with isophorone ~i~r; ne.
A further aminoamide is disclosed in U.S. ~atent No. 5,391,826
and characterized in that it is a diamidotriamine from the
reaction of glutamic acid and isophorone ~; ~m; ne ~t is
disclosed in this document that the product may be used as raw
material for the preparation of fuel and lubricant additives but
~ there is no further information on the preparations as such and
on the effect.
Attempts have been made to use heteroatoms based on sulfur,
- phosphorus, and silicon as high temperature corrosion inhibitors.
Eowever, these materials can produce new problems, such as
poisoning catalysts in refinery systems, accelerated corrosion
from degradation products and the creation of environmental
hazards associated with discharges from the treated system (i.e.,
Nox, S0x, phosphate, etc.).
T~ere~ore,. materials that are.based on carbon, hydrogen, oxygen
and .nitrogen are preferred candidates for high temperature
corrosion inhibitors.
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It is therefore a first object of this invention to provide new
corrosion inhibitors based on C, H, 0 and N which maintain a
substantial degree of their efficiency even at high temperature,
i.e., within the range of about lSOa to about 4500C. It is a
further object to provide a method for corrosion inhibition at
said high temperature range with or without high pressure. The
method and the compositions therefore are applicable under high
temperature conditions in gas and oil wells as well as in other
environments as disclosed herein.
~ummary of the Invention
It has been found that when carboxylic acids, preferably fatty
acids, are treated with branched or cyclic polyamines, preferably
~;~ ;nes which do not form cyclic 5- and 6-~embered rings in
significant amounts, the resulting aminoamides have good thermal
stability, solubility, and corrosion inhibition performance.
Specifically, these compounds are very suitable for use in
dr;ll ;n~ fluids, deep-hot gas, oil, and geothermal wells, certain
refinery operations, and other fields. The compounds are also
useful for incorporation into heat transfer fluids, lubricating
fluids, lubricants, coatings, adhesives, plastics, fire
retardants and the like.
For inhibiting corrosion on metal surfaces, said aminoamide is
brought into contact with said metal surfaces in an ef~ective
amount in liquid phase which may be the neat corrosion inhibitor
in molten form, or a solution or a dispersion o~ it.
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The corrosion inhibitor is an aminoamide of~-the general ~~ la
Rl-Co-NR2-Z-NR3R~ (I) or mixtures thereo~, in which Z is a divalent
aliphatic radical having a branched carbon chain or a divalent
alicyclic ring system including ring systems with one or two
attached alkylene groups and/or alkyl groups whereby said
radicals comprise a carbon chain'with at least three carbon atoms
between the attached NR2- and NR3R4-group and whereby the
structural element -NRZ-Z-NR3R~ of ~ormula (I) does essentially
not ~orm an imidazoline or tetrahydropyrimidine ring system.
R2, R3, and R4 are each, independent o~ the other, hydrogen, an
aliphatic, alicyclic or aromatic radical, wherein aromatic
radicals are less pre~erred.
Rl is a monovalent monomer or polymer radical preferably having
an ~le~phiiic por~ion, comprising a saturated or ole~inic l;ne~r
or branched hydrocarbon radical, an alicyclic or aromatic radical
of which an aromatic radical is less pre~erred and an alkyl,
alkenyl or alkadienyl radical with 3 to 30 carbon a~oms, most
pre~erably ~ to 22 carbon atoms is pre~erred, or a salt thereof.
The Rl radicals may also contain one or more substituents
selected ~rom the group consisting o~ carboxyl, amino and
~ydroxyl. The "alicyclic" and "aromatic" radicals also include
the corresponding alkyl substituted radicals.
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~refer~ed Embodiment
The aminoamide corrosion inhibitors themselves can be
manufactured in a generally known manner. A carboxylic acid of
the general formula Rl-COOH or a derivative thereof such as
an ester Rl-CooR5 where Rs is a hydrocarbon radical
such as alkyl and the like,
an amide RlCoNR6R7 wherein R6 and R7 are hydrogen or a
hydrocarbon radical such as alkyl and the li~e,
an acid halide RICOX where X is a halogen, or
an acid anhydride RICO2Rl,
is reacted with an amine o~ the general ~ormula R2HN-Z-NR3R4,
wherein Rl, R2, R3, R4 and Z have the above mentioned m~An;n~.
During the amidation, usually at a temperature of about 100~ to
300~C, pre~erably at 150~ to 250~C, within 0.5 to 20 h, the
r ;no~~;t1e (I) i5 formed. In the reaction, mixtures o~
aminoamides may be formed and these may be employed as such or
puri~ied to obtain a single pure compound.
The amine of formula R2HN-Z-NR3R~ is preferably a ~;~ ;ne, but one
or more of the groups R2, R3 and R4 may comprise ~urther amino
groups, e.g., aminoalkyl groups. Those aminoalkyl groups ~or R2,
R3 or R4 which may form an ; ;~oline or tetrahydropyrimidine
ring are excluded. R2, R3 and R~ are preferably hydrogen or a
lower alXyl group of l to 5 carbon atoms and each may be the same
or they may be different. Illustrative ar~ methyl, ethyl, n-
propyl, isopropyl with methyl being preferred. ~ost pre~erred
are diamines o~ the ~ormula H2N-Z-NH2.
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one particularly interesting group of amines which may be
mentioned are those in which at least one of the carbon atoms
beta to the amino group or groups present is quaternary.
A preferred ~~~ning for Z is a branched alkylene group wherein
the chain between the amino groups to which Z is attached has at
least 3 carbon atoms and said chain has at least one, preferably
more than one, lower alkyl substituents, such as methyl and
ethyl. It is important that Z be such that the structural
element -NR2-Z-NR3R~ of formula (I) essentially does not ~orm an
imidazoline or tetrahydropyrimidine ring system. Most preferred
branched alkylene groups have 6 to 10 carbon atoms. Examples of
diamines of the formula H2N-Z-NH2 are: 2,2-dimethyl-1,3-
~;Aml n~propane; 2-methyl-1,4-~;~ ;nobutane; 2-ethyl-1,5-
~;~;nopentane; 2,4,4- or 1~l~3-trimethyl-l~6-~;~m;no~ ne; 2-
methyl-1,5-~;nopentane; 2-ethyl-2-butyl-1,5-~;~;nopentane.
Examples of triamines are 4-r-;n~thyl-1,8-~;~;nooctane and N-
substituted di-1,3-propylenetriaminewhereinthesubstituents are
such as to avoid ring formation. Others which may be mentioned
are 1-t2-aminomethyl)-piperazine, 1-(2-aminomethyl)-4-amino-
piperidine and 4-methyl-1,4,7-triazaheptane.
Another preferred ~ning for Z comprises a mono-, di- or
tricyclic ~ive- and/or six-membered cycloaliphatic ring system.
In this ~n; ng, z preferably contains 6 to 12 carbon atoms. The
ring system may comprise lower alkyl substituents, e.g., methyl,
ethyl, n- or iso-propyl. One or both of the amino groups
attached to Z may be linked thereto directly at a secondary or
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~tertiary carbon atom of the ring system or may be l;nke~ at an
alkyl substituent. ~xamples of cyclic ~;Ar;nes o~ ~ormula H2N-Z-
NH2 are: 1,4-- and 1,3-~ 9 ;nocyclohexane ~The trans isomer of
both, the 1,4- and 1,3-diaminocyclohexane, is pre~erred because
said ;~ ?r cannot ~orm cyclics. In order to a~oid ring
~ormation o~ the cis-isomers, at least one nitrogen atom o~ the
~;~;ne should be su~ficiently substituted.]; 1,3- or 1,4-bis-
(aminomethyl)cyclohexane;bis(4-aminocyclohexyl)-methane;bis(4-
amino-3-methylcyclohexyl)-methane; 1-amino-3-aminomethyl-3,5,5-
trimethylcyclohexane (=isophorone~;~; n ~ ); 3(4), 8 ( 9 ) - bis(amino-
methyl)-tricyclo~5,2,1,0i6~ ~cAne; 2(3),5(6)-bis(~;no~ethyl)-
bicyclo~2,2,1 ]heptane(=~ ;no~thyl-norbornylene) ;i,8--r~;~;no-
l-methyl-4-isopropyl-cyclohexane (=1, 8 - ~; ~; nomenthane) and 3-
cyclohexyl-aminopropyl-amine.
Z r.ay also ~e a diva~ent aromati~ or aro~atic~ tic ra~ica~,
like e.g., meta- or para-phenylene or -C6H~-(C~2)3, but usually
such radicals are less pre~erred c _-~ed to said aliphatic or
alicyclic radicals.
The Rl r~;c~l o~ the carboxylic acid part of the aminoamide can
be linear or branched, aliphatic or cycloaliphatic, saturated or
unsaturated or aromatic; aromatic is less pre~erred. Said R1
radical may also contain one or more substituents selected from
the group consisting o~ carboxyl, amino and hydroxyl. Pure
carboxylic acids or mixtures o~ natural or synthetic carboxylic
acids can be used. A linear alkyl or alkenyl group R~ with 7 to
22 carbon atoms is most favored. In ca~e o~ a suf~iciently
, , , CA 02249171 1998-09-30
oleophilic group RZ, R3 or ~, then Rt may be a short chain
radical, otherwise a radical Rl with at least 4 carbon atoms is
preferred;
Examples of saturated aliphatic fatty acids are: formic, acetic,
propionic, butyric, valeric, caproic, haptanoic, caprylic,
nonanoic, capric, undecanoic, lauric, tridecanoic, myriatic,
~pentadecanoic, palmitic, heptadecanoic, stearic, nonadecanoic,
eicosanoic, heneicosanoic, docosanoic, trocosanoic,
tetracosanoic, pentacosanoic, cerotic, heptacosanoic, montanic,
nonacosanoic, melissia, and the like.
Examples of ethylenic aliphatic carboxylic acids are the
pentenoic acids, the hexenoic acids, the octenoic acids, the
nonenoic acids, the decenoic acids, the tridecenoic acids, the
tetradeceneoic acids, the pentadecenoic acids, the hexadecenoic
acids, the heptadecenoic acids, the octadecenoic acids, the
nonadecenoic acids, the eisosenoic acids, the decosenoic acids,
the tetracosenoic acids.
Examples of cyclic aliphatic acids are: naphthenic acids,
hydrocarbic and chaulmoogric acids, cyclopentane carboxylic
acids, cyclohexanecarboxylic acids, G~ -_horic acid, and ~encholic
acid.
Examples of mixed fatty acids are those as obt~;n~hle from lard
oil, coconut oil, rapeseed oil, sesame oil, tall oil, palm oil,
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palm kernel oil, olive oil, corn oil, cottonseed oil, dardine
oil, tallow, soya bean oil, peanut oil, castor oil, seal oils
shale oils, shark oils, other fish oils, teaseed oil, partially
or completely hydrogenated Ani ~1 or vegetable oils or obt~in~hle
from waxes like beeswax, spermaceti, montan, Japan wax, coccerin,
and carnuba wax, paraffin wax, petroleum jelly, naphthenics, and
blown oil fatty acids.
It is also possibIe to use di- and polycarboxylic acids,
preferably in combination with monocarboxylic acids. Examples
of Al ;ph~tiC polycarboxylic acids are: oxalic, malonic, succinic~
glutaric, adipic, pimelic, suberic, azelaic, sebacic,
nonadicarboxylic, decanedicarboxylic undecanedicarboxylic,
tartaric, fumaric, maleic, mesoconic, citraconic, glutonic,
itaconic, muconic, aconitic, and the like. Industrial polymeric,
i.e., dimeric and higher ral~y acids are aiso usefui in ~his
invention.
An example of a hydroxyl group-cont~;nin~ acid of the formula Rl-
COOH i8 9,10--dihydroxystearic acid. Bxamples of amino group--
cont~in~ng acids are 6-amino caproic acid, aspartic acid and
glutamic acid.
Additionally, the ratio of fatty acid to amino functionality can
be broad. The normal ratio is about one carboxylic acid group
per every two amino groups in the di- or polyamine raw material.
However, other ratios are useful. For instance, the ratio can
favor ~c~sc fatty acid or ~c~ss polyamine. As to a further
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embodiment, salts of the aminoamides can also be useful. A salt
can be formed via unreacted fatty acid and the amino group of the
aminoamide product. Salts can also be formed by the addition of
other acids to the aminoamide product. The other acids may be
fatty acids, hydroxycarboxylic acids such as hydroxyacetic acid,
mineral acids, such as hydrochloric acid, polymeric acids, such
as polyacrylic and polymethacrylic acids and their copolymeric
polyacids with a variety of comonomers. Comonomers which can be
mentioned are crotonic acid, fumaric acid, itaconic acid, maleic
acid, allyl alcohol, acrylamide, methacrylamide, acrylonitrile,
acrolein, methacrolein, butyl acrylate, butyl methacrylate, ethyl
acrylate, ethyl methacrylate, methyl acrylate, methyl methacryl-
ate, vinyl acetate, 2-hydroxyethyl acrylate, 2-hydroxyethyl meth-
acrylate, styrene, butadiene, 2-carboxyethylacrylate and 2-
carboxyethylmethacrylate.
In addition to the above illustrations, blends of the individual
components are also useful with the scope of this invention.
In accordance with the invention corrosion inhibition is achieved
on metal sur~aces, for example, mild (carbon) steel, wrought
irons, cast irons, stainless steels and the like, by bringing
said metal sur~ace into contact with an effective amount of the
aminoamide corrosion inhibitor of the present invention. Where
flowing liquid systems cont~; n; ng the corrosion inhibitor are
contacted with the metal surface the effective amount is about
1 to 100 parts or higher of the aminoamide per million parts of
iiquid. For static systems, e.g., batch processes, the quantity
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may be about 1 to 10,000 ppm. Inhibition is also possible by
dipping, smearing, spraying, etc., the metal sur~ace with the
pure (neat) aminoamide inhibitor or a composition contA;n;ng ~he
inhibitor in, for example, an amount o~ about 1 to 99% by weight
of the composition.
The invention also provides novel aminoamide products of the
general ~ormula Rl-Co-NR2-z-NR3R~ These are amidation products
of A~ i n~ o~ the general ~ormula R2-NH-Z-NR3R~ with Rl-COO~ or a
reactive derivative thereo~ with the proviso that ~atty acid
A~;~S 0~ isophorone A;A~;ne and diamidotriamines based on
glutamic acid are excluded. Taking into regard the previously
stated exceptions, R~, RZ, R3, R4 and Z are as de~ined above
herein. Of particular note are amfnoamides based on a C~ to ~0 -
and more preferably on a C~ to C~-fatty acid, which may be
saturated or ha~e ole~inic groups and a branched or cyclic
~;~;ne, pre~erably one of the ~ollowing ~;~r;nes:
2,2-dimethyl-1,3-diaminopropane; 2-methyl-1,4-diaminobutane; 2-
ethyl-1,5-diaminopentane; 2,2,4-or 1,1,3-trimethyl-1,6-~;~;no-
hexane; Z-methyl-~,5-diaminopentane and 2-ethyl-2-butyl-1,5-
~ i A ; ~opentane;trans-1,4-andtrans-1,3-diaminocyclohexane;1,3-
or 1,4-bis-( ;no~~thyl)cycloheYAne; bis(4-aminocyclohexyl)-
methane; bis(4-amino-3-methylcyclohexyl)-methane, 1-amino-3-
aminomethyl-3,5,5-trimethylcyclohexane (=isophorone ~;~;ne);
3(4),8(9)-bis(aminomethyl)-tricyclo[5,2,1,026]decane;2(3),5(6)-
bis(aminomethyl)-bicyclo[2,2,1]heptane(=diaminomethyl-
norbornylene); and 1,8-diamino-1-methyl-4-isopropyl-cyclohexane
(=1,8-~;A~;nomenthane).
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In the method of this invention, the above aminoamides are used
as COl osion inhibitors in the neat form, or as part of a
corrosion inhibiting composition, which comprises solutions with
various solvents. The solvents may be selected from: aliphatic,
cycloaliphatic and aromatic solvents, ~y~thetic alkylbenzenes and
hydrocarbon polymers. Examples of aliphatic solvents are:
hexanes, heptanes, octanes, nonanes, decanes, undecanes,
dodecanes, tridecanes, tetradecanes, pentadecanes, hexadecanes,
naphthas, gasolines, diesel, jet A fuel, kerosenes, terpentines,
branched aliphatics such as isooctane, cycloaliphatics such as
cyclohexane and methylcyclohexane and decahydronaphthalenes.
Blends of hydrocarbon oils, waxes, and greases are also useful
in this invention.
Examples of aromatic solvents are: benzene, toluene, xylenes,
mesitylene, dihydronaphthalene, tetrahydronaphthalene, cymene,
cumene, ethylbenzene, propylbenzene, butylbenzene,
phenylpentanes, phenylhe~n~s, phenylheptanes, phenyloctanes,
phenylnonanes, phenyldecanes, phenylundecanes, phenyldodecanes,
phenyltridecanes, phenyltetradecanes, phenylpentadecanes,
phenylhexadecanes,phenylheptadecanes,phenyloctadecanes,andthe
li~e. Blends of aromatic solvents such as heavy aromatic
solvents, as well as blends o~ the above are also useful in this
invention.
Examples of polymeric hydrocarbon solvents are: polybutadienes,
polybutenes, polypropylenes, and blends thereof.
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In most cases, the use~ul corrosion inhibitor is oil soluble.
However, in some cases it is advantageous that the inhibitor be
water dispersible. This can be done by using the above-mentioned
salt derivatives. It can also be done using cosolvents.
Examples of use~ul cosolvents are: methanol, ethanol,
isopropanol, butanols, ethylhexanol, methylpropanols, carbitols,
cellosolves, dimethylformamide, methylpyrrolidinone, dimethyl-
sulfoxide, glyme, diglyme, ethylene glycol, diethylene glycol,
and the like. Some of these materials also function as
winterizing agents, e.g., ethylene glycol.
Sometimes, adjuvants are added to the inhibitor's ~ormulation,
especially, surfactants. These surfactants can be anionic,
cationic or nonionic in nature. Examples are: alkylsul~(on)ates,
alkylcarboxylates, quaternized ammonium salts, and polyoxyethyl-
enes, polyoxypropylenes, polyoxybutylenes, and various mixtures
of the above.
In general, the corrosion inhibitlng compositions comprise the
aminoamide o~ the general formula (I) above, or mixtures thereof,
dissolved in an aliphatic, aromatic, alkyl-aromatic or cyclo-
~l;ph~tic hydrocarbon solvent or a hydrocarbon polymer ordisper~ed in water or an aqueous-organic solvent mixture. The
amount of the aminoamide or mixture thereof is in the range of
1 to 99% by weight of the composition. The amount is preferably
1 to 60% by weight and more preferably 10 to 50% by weight.
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As a rule, corrosion takes the form of generalized corrosion,
although other specialized forms also exist. Useful corrosion
inhibition ~h~nisms can rely on neutralization of the corrosive
agents, and/or by forming a protective film on the metal's
tsurface. Increasing temperature generally causes corrosion rates
to be accelerated. Increasing pressure can also accelerate
corrosion because corrosive agents; like C02 and H2S, can be
dissolved in the liquid phase up to a highly corrosive
concentration. By using the aminoamides o~ the invention, the
corrosive action of C0~, H2S, b~ines, oxygen and air can be
controlled. Also these aminoamides can control corrosion caused
by acids.
Aminoamide corrosion inhibitors of this invention neutralize
acidic corrosive agents via the amino function. The amino group
also allows for the attachment to the metal surface, ~orming a
protective film. The inhibitors are characterized by their
unexpected high thermal stability and therefore are capable of
being used above 150~C or even above 190~C. lt has been found
that the corrosion effectiveness is still very high at 290~ to
400~C and even at higher temperatures, e.g., at 450~C.
~orrosion protection can therefore be realized quite effectively
by applying the aminoamides of this invention in those ~ields
where other inhibitors fail. The aminoamides can'be applied per
se or incorporated in a composition continuously at or up-stream
of the area to be treated. Alternatively, it can be applied
semi-continuously or in a batch ~nn~r at desired intervals of
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~ , CA 02249171 1998-09-30
, .
time. Under certain oilfield systems, the chemical can be
applied via a "squeeze" type operation. In this case, the system
is backflowed and the chemical is applied downstream o~ the
in~n~e~ treating area. The backflowing causes the chemical to
pass the target zone and proceed upstream of that area. The
system is then flowed in the normal direction, and the chemical
again passes the target zone. It is, of course, important that
the chemical reach the point or points in the system where
corrosive action occurs and this can be accomplished in various
ways ~nown to the art-skilled. In flowing systems, use can be
made of "stingers" in which the chemical is injected into the
~lowing stream, such as, for example, into a surge tank or a flow
line. The aminoamides can also be incorporated into lubricant
compositions which can simply be applied to the metal to be
protected.
When the aminoamides of this invention are applied, and the
system is at high temperature, or experiences sporadic high
temperature/low temperature cycles, these materials will provide
corrosion protection when typical ~;~;neS, imidazolines, and
tetrahydropyrimidines or salts therefrom fail due to degradation.
Additionally, these amino~ i~es usually have better solubility
characteristics than some of the current inhibitors. The
_roved ~h.~ ~1 stability of these aminoamides will also mean
that less gunking/fouling will be observed when they are used and
thus it is not necessary to replace the steel parts frequently.
~ - .. ... .... . .. . ,,__,... ....
~ CA 02249171 1998-09-30
,
~ ,
Potential applications where benefit ~rom the application o~
aminoamides from this invention can be realized include deep hot
gas, oil, and geothermal producing wells with bottom hold
temperatures above 150~C or even above 190~C, and refinery
operations with system temperatures up to or even above about
4000C, especially where potential catalyst poisoning by
heteroatom-cont~;n;ng materials would present a serious problem.
Coatings for the protection of metals at high temperatures can
also bene~it from incorporating the aminoamide corrosion
inhibitors of this invention as adjuvants to the coating's
formulation.
The use of these aminoamides in lubricants, heat transfer fluids,
and as additives ~or plastics for the protection o~ metallic
surfaces against corrosion are further applications.
In respect to lubricants and metal:working fluids, U.S. Patents
No. 4,210,542, No. 4,196,091, No. 4-,259,206 and No. 4,273,664
provide extensive discussion. By replacing the organo-nitrogen
materials described in these patents with the aminoamides of the
present invention, better thermal stability and better corrosion
protection under similar stated circumstances can be achieved.
U.S. Patent No. 4,261,842 describes the use of amines as
corrosion inhibitors in glass processing. The corrosion in-
hibitors are used in aqueous media. The aminoamides of the
present invention as salts or in cosolvents will perform in a
superior manner if they are substituted for the organonitrogen
materials disclosed in the patent.
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' t . ,~ CA 02249171 1998-09-30
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The methods and apparatus for employing corrosion inhibitors in
refineries, in petroleum wells and in drilling operations are
well known in the art and the ~; nor~ corrosion inhibitors of
the present invention can be employed by replacing the previously
employed inhibitors by than the invention. Exemplary reference
is made to 'ICorrosion Inhibitors'l edited by C.C. Nathan, National
Association of Corrosion Engineers, Eouston, Texas (1973) and
particularly to pages 46-47, 65-68 and 81 and 106 and 108-111.
In connection with the employment of the amino~ s in plastics,
it is noted that most plastics are manufactured ~rom monomers via
catalysts. ~ost of the catalysts are acidic, and they are le~t
within the ~inished plastic material. When such plastics are
exposed to high temperature hostile environments, acidic
materials are released, thereby causing corrosion to various
metallic surfaces. Some of the corrosive agents released by the
degradation of plastics are: hydrochloric acid, acetic acid,
formic acid, formaldehyde, SOi, NOX, PO~ and H~. The equipment
used to mold, extrude, shape, etc., can be corroded by the
degrading plastics. The inhibitors of this invention can be
incorporated into plastics at the time o~ manufacture, so that
their further processing can have reduced corrosion.
Plastics are often used in various applications that experience
hostile, high temperatures. These include actual hardware
fabricated from plastic such as vessels, reactors piping, tanks,
mixers, valves, etc., as well as coatings, adhesives, gaskets,
sealants, and insulation ~or the e~uipment. By incorporating the
... . . . ... .. .... .. .
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; CA 02249171 1998-09-30
aminoamide inhibitors of the invention into the plastics,
corrosion of metals in contact with the plastics will be avoided.
Plastics which can be mentioned are: ABS (ACS, ASA), acetal
homopolymers, acetal copolymers, polyvinylchloride, acrylics,
bismaleimides, cellulosics, epoxies, fluoroplastics, ionomers,
liquid crystal plastics, melamines, nitrile resins, nylons,
phenolics, phenyleneresins,polyamide-polyimides,polyacrylates,
polyarylsulfones; polymethacrylics, polybutylenes,
polycarbonates, polyesters, thermoplastics, thermosets,
polyetheretherketones, polyetherimides, polyethylenes,
polyethylenes, polymethylpentenes, polystyrenes, polysulfones,
polyurethanes, polyvinyls, vinyls, polysilicones, styrenic
copolymers, polyureas, vinylidene chloride copolymers, and
others, as well as mixtures of the above.
A similar issue is that of elastomers. These are natural
rubbers, latexes, ethylene/acrylics, polythioethers, ethylene/-
propylene copolymers, epoxidized natural rubbers, polyphenylene
sulf ides, polyamide/polyimides, fluoroelastomers, silicone
rubbers, phosphonitrilic fluoroelastomers, nitrile elastomers,
epichlorohydrin elastomers. As with plastics, the amino~ es
çan be incorporated in likc ~n~er.
A further potential use of the amindamides is for incorporation
into cements (concrete) as well as into ceramics which are
employed with metals. By incorporation of these inhibitors,
corrosion of the contacting metal can be avoided.
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~ ~ t . CA 02249171 1998-09-30
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The ~cope of this invention is illustrated, but not limited to,
the following examples:
EX~MP~E 1
Preparation of Imidazoline from Tall Oil Fatty Acid and
DiethYlenetriamine:
A 500 ml four-neck flask was charged with 251.12 grams of tall
oil fatty acid (Acintol FA-2, Arizona Chemical Company) and 92.53
grams of diethylenetriamine (Union Carbide). The ~lask was
equipped with a magnetic stirrer, pot thermometer, and a Barret
trap with reflux condenser. The flask was placed under nitrogen,
and heated to 250~C over 12 hours. The heating process used a
ramping te~hn;que wit-h the foliowing temperature/time data:
105~/50 min., 157~C/115 min., 205~C/6 hours, 245~C/10 hours,
250~C/12 hours. During the heating period, 35 ml of condensate
material was obtained in the trap; 29 ml was water cont~;n;ng
abaut 1 gram of starting tr;~;n~, and 6 ml oily layer composed
of triamine and lower molec~ ~ weight carboxylic acid residues.
The ramping t~chn;que ~; ;n;~hed the amount of foaming during the
reaction in the pot. The reaction afforded 260 grams of the
imidazoline product. This imidazoline was soluble in hexadecane,
synthetic aromatic solvent (Alkylate 230, Monsanto), and p-
cymene; it had a pour point of -32OC (ASTM D97-66); IR (neat~
3z65 (broad), 2915, 2845, 1605, 1460, 1255, 1013, 988, and 725
cm~~.
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.
CA 02249171 1998-09-30
The ~atty acid composition o~ the employed Actinol FA-2 is as
follows:
Palmitic Acid, % 0.1
Palmitoleic Acid, % 0.2
Unknown Acid, ~ 0.1
SteariC Acid, % 2.5
Oleic Acid, % 49.5
Unknown Acid, % 1.6
Linoleic Acid (cis-9, cis-12), % 35.7
Unknown Acid, ~ 3.1
.Unknown.Acid, ~ 0.4
Linoleic Acid ~cis-9, trans-11), ~ 2.6
Eicosanoic Acid, ~ 1.4
Linoleic Acid (trans-9, trans-11),~1.2
Eicosanoic Acid, % 0 5
Eioosatrienoic ACid, % O.4
Behenic Acid, % 0 7
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. ~ CA 02249171 1998-09-30
~XAMPLE 2
Preparation of ~ oline from Tall Oil ~atty Aci~ ana Hydroxy-
e~hyl--ethYlene~ ; ne
A 500 ml four-neck flask was charged with 250.00 grams of tall
oil fatty acid (Aaintol FA-2, Arizona Chemical Comp~ny) and 98.42
grams of N-hydroxyethylethylen~ m ine. The reaction was
operated in the ~nn~r described in Example 1. After 12 hours,
the reaction was halted. The temperature within the pot had
risen to 248~C, and the trap cont~;ne~ 39 ml agueous layer and
8 ml oily layer. The reaction produced 302 grams of the
imidazoline product. This imidazoline was not soluble in
hexadecane, but was soluble in synthetic aromatic solvent
~- (Alkylate 230, Monsanto) and p-cymene; it had a melting point of
32-38~C; IR (neat) 3290, 2920, 2825, 1630, 1555, 1540, 1460,
1415, 1265 and 720 cm~l.
E~aMP~E 3
Preparation of N-Oleyl-1,3-Prop~ne~i~m;ne ~rom Oleylamine and 3-
Chloro-l-amino~ro~ane:
A 500 ml three-neck flask was charged with 267.5 grams of
oleylamine and 98.25 grams of 3-chloro-1-aminopropane. The flask
was eguipped with magnetic stirrer, pot thermometer, and reflux
condenser. The mixture was heated to 100~C for 20 hours, and
~hen cooled to room temperature. The crude mixture was poured
into a separatory funnel, and 150 grams of water cont~;n;ng loo
grams of sodium hydroxide was slowly added. Additional sodium
hydroxide pellets were added until no more could be dissolved.
The mixture was shaken and two layers developed. The upper oily
layer was removed, and placed into 250 ml dried tetrahydro~uran.
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. , CA 02249171 1998-09-30
The solution was dried with anhydrou5 ~odium carbonate, and the
tetrahydrofuran removed at reduced pressure. In this way, 227
grams of the oleyldiamine were obtained- This fatty diamine had
a melting point of 24-29~C, and was not soluble in h~xa~ec~ne~
synthetic aromatic solvent (Alkylate 230, Monsanto), or p-cymene;
IR (neat) 3210 (broad), 2920, 2850, 1605, 1460, 1375, 1130, 975
and 725 cm~~.
BX~MP~ 4
Preparation of Aminoamide from Tall Oil Fatty Acid and Isophorone
Diamine
A 100 ml three-neck flask was charged with 33.36 grams of tall
oil fatty acid (-Acintol FA-2, Arizona Chemical Company) and 20.44
grams of isophorone ~;~;ne (Degamin IPDA, Degussa AG~. The
flask was equipped with a magnetic stirrer, pot thermometer and
a Barett trap with condenser. The reaction mixture was heated
for one hour with the temperature being ramped from 180~C up to
306~C. About 0.1 gram of unreacted isophorone ~;~;n~ were found
in the condensate. This process yielded 50.8 grams of the
aminoamide product. The aminoamide had a pour point of -21~C
(AST~ D97-66) and was soluble in hexadecane, synthetic aromatic
solvent (Alkylate 230, ~onsanto), and p-cymene; IR (neat) 3290,
3060, 2965, 2850, 1640, 1545, 1460, 1385, 1365, 1305, 1250, 1220,
970, and 75 cm~.
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. ,:
' . . , . CA 02249171 1998-09-30
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- EXP~IPI.E 5
Preparation of Aminoamide from Tall Oil Fatty Acid and 1,8-
~iamino-p-menthane
A 100 ml three-neck flask was charged with 24.12 grams o* tall
oil fatty acid (Acintol FA-2, Arizona Chemical Company) and 23.84
grams of 1,8-~i~ino-p-menthane (Aldrich Chemical Company). The
flask was equipped with a magnetic stirrer, pot thermometer, and
a Barret trap with a condenser. The mixture was heated for 85
minutes, up to a temperature o* 298OC, then cooled to room
temperature. The trap contained 2.5 ml of water with 0.1 grams
of starting diamine, and 0.6 ml of oily material. This procedure
yielded 44.44 grams o* the aminoamide product. The aminoamide
~ product was not soluble in hexadecane, but was soluble in
synthetic aromatic solvent (Alkylate 230, Monsanto) and ~-cymene;
IR (neat) 3280, 3050, 2910, 2840, 1630, 1535, 1445, 1360, 1270,
1173, 1135, 970, 812 and 722 cm~l.
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~ CA 02249171 1998-09-30
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EXAMPLE 6
Preparation of Aminoamide from Tall Oil Fatty Acid and m-Xyly-
lenediamine
A 100 ml three neck fla5k was charged with 53.83 grams of tall
oil fatty acid (Acintol FA-2, Arizona Chemical Company) and 25.88
grams of m-xylenediamine (Aldrich Chemical Company). The flask
was equipped with a magnetic stirrer, pot thermometer, and a
Barret trap with condenser. The mixture was heated for one hour,
with the pot temperature reaching 266~C. The mix was cooled.
The trap contained 3.3 ml of water with 0.1 grams of unreacted
diamine. This procedure afforded 75.07 grams of the aminoamide
product. This aminoamide product had a melting point o~ 34-43~C,
and was not soluble in hexadecane, but was soluble in synthetic
aromatic solvent (Alkylate 230, Monsanto) and ~-cymene: IR
(neat) 3190, 3050, 3010, 2900 (broad), 1655, 163~, 1610, 1560,
1545, 1525, 1465, 1440, 1425, 1380, 1350, 1330~ 1250, 1160 lQ~9,
895, 795, and 705 cm~1.
,
E~AMPL~ 7
Preparation of Aminoamide from Tall Oil Fatty Acid and 1,4-
PhenYlenediamine
A 100 ml three-neck flask was charged with 36.14 grams of tall
oil fatty aaid (Acintol FA-2, Arizona Chemical C _Any) and 14.06
grams of 1,4-phenylen~i A~; ne (Aldrich Chemical Company). The
flask was e~uipped with a magnetic stirrer, pot thermometer, and
a Barret trap with condenser. The mixture was heated ~or one
hour with the pot attA;ning a temperature of 282OC. The mixture
was cooled. The trap contained 2.2 ml of water with 0.1 grams
of unreacted diamine. This process yielded 47.69 grams of the
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~ CA 02249171 1998-09-30
f .
aminoamide product. This aminoamide had a melting point o~ 84-
91~C, and was not soluble in hexadecane, synthetic aromatic
solvent (Alkylate 230, Monsanto) or ~-cymene; IR (neat) 3360,
3345, 3290, 3000, 2910, 2840, 1645, 1590, 1520 (broad), 1455,
1420, 1395, 1370, 1300, 1255~ 1180, 1110, 1090, 960, 830, 710
(broad) and 505 cm-~.
EXAMPLE 8
Preparation of Aminoamide ~rom Tall Oil Fatty Acid and 1,~-
Diaminooctane
A 100 ml flask was charged with 38.,92 grams o~ tall oil ~atty
acid (Acintol FA-2, Arizona Chemical Company) and 20.2 grams of
1,8~ r; nooctane (Aldrich Chemical Company). The flask was
~itted with a magnetic stirrer, pot thermometer, and a Barret
trap with condenser. The mixture was heated for 34 minutes, with
the pot reaching 246~C. The mixture was then cooled. The trap
cont~;n~ 2.5 ml water with 0.1 gram of unreacted ~;~;ne, This
reaction af~orded 51.75 grams of the A~;no~ e product. The
aminoamide had a melting point of 54-70~C, and was not soluble
in hexadecane, synthetic aromatic solvent (Alkylate 230,
Monsanto), or ~-cymene; IR (neat) 3210, 3050, 3010, 2800 (broad),
1630j 1545, 1525, 1460, 1418, 1375, 1260, 1228, 1194, 1076, 945,
820, 725 (s, broad), and 565 cm~l.
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CA 02249l7l l998-09-30
EX~MPLE g
Preparation of A~; noA~; de from Tall Oil Fatty Acid and D;~; nn -
methYlnorbornylene
A 100 ml three-neck flask was charged with 33.36 g of tall oil
fatty acid (Acintol FA-2, Arizona Chemical Company) and 18.51
grams of diaminomethylnorbornylene (NBDA, Mitsui Toaksu
Chemicals, Inc.). The flask was equipped with a magnetic
stirrer, pot thermometer, and a Barret trap with condenser. The
mixture was heated for 45 minutes and the pot attained a
temperature of 306~C. Afterwards, the mixture was cooled. the
trap contained 2.0 ml water with 0.1 gram unreacted ~; ; ne .
This method provided 48.88 grams of the aminoamide. The amino-
amide was not soluble in hexadecane, but was soluble in synthetic
aromatic solvent (Alkylate 230, ~onsanto) and ~-cymene; it has
a pour point of -17~C (ASTM D97-66); IR (neat) 3280, 3065, 3005,
2920, 2850, 1630, 1545, 1455, 1378, 1260, and 725 cm~l.
~XAMPLE 1o
Preparation of Aminoamide from Tall Oil Fatty acid and 2,2,4-Tri-
methYl-1 6-hexanediamine
A 100 ml three-neck flask was charged with 33.36 grams of tall
oil fatty acid (Acintol FA-2, Arizona Chemical Company) and 19.0
grams of 2,2,4-trimethyl-1,6-hexan~ ~;ne (Vestamin TMD, Huls).
The flask was fitted with a magnetic stirrer, pot thermometer,
and a Barret trap with condenser. The mixture was heated for
33 minutes with the pot att~;n;ng 268~C. The mixture was then
cooled. The trap contained 2.1 ml water with 0.1 gram of
hnreacted diamine. The procedure yielded 49.26 grams of the
aminoamide product. The aminoamide had a pour point of -22OC
S ; - -, - . . .
. . .
~ .- ,' CA 02249171 1998-09-30
.
(ASTM D97-66), and was soluble in h~cAne~ synthetic aromatic
solvent (Alkylate 230, Monsanto), and ~-cymene; IR (neat) 327s,
3025, 2997, 2915, 2845, 1635, 14G0, 1365, 1255, and 725 cm~l.
~XAMPLE 11
Thermal Degradation Studies at 290~c under Air with 1010 Mild
Steel
One ml glass ampules were filled with a 0.25 ml sample along with
4 cm oP 22 gauge 1010 mild steel wire. The ampules were sealed
under air and placed in a muffle furnace at a constant
t m,?rature o~ 290~C. Over time, ampules were removed from the
furnace and cooled, then opened. The contents were subjected to
infrared analyses. The ratio of the absorbances of the
chemical's active frequency versus that of an inactive
hydrocarbon frequency was determined, and these were then
norr~;zed to the ratio for the untreated case. Table 1 shows
the infrared frequencies used for each chemical evaluated, and
Table 2 displays the normalized data versus time.
_.. _, _ . . _ . _ _ . . . . ..
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~ ' ,' CA 02249l7l l998-09-30
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Table 1 - Infrared Freouencies for Evaluated Chemicals
Inactive
Example Number of ChemiCal Active Freguency Freguency
Evaluated (c~) (cm~l)
1 1605 1460
2 . 1630 1460
3 1130 1460
4 1640 1460
1630 1445
6 1635 1465
7 1645 1515
8 1630 1460
9 1630 1455
1635 1460
All infrared freguencies given in Table 1 were obtained by the
analysis of neat samples in a Beckman ACc~ h 6 double beam
spectrophotometer using KBr salt plates. The active fre~uencies
~or Example 1 and 2 are the i ;~zoline bands; i~or Example 3, it
was the secondary amine; for all others, it was the ~;no~mide
carbonyl.
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CA 02249171 1998-09-30
Table 2. Degradation Data for Various Chemicals at 290~C under
Air with 1010 Mild 5teel
No~ ed Ratio (active/inactive)
Example
h~t- @lO hr@ 20 hr @30 hr@ 40 hr@50 hr
1 0.98 0.97 0.96 0.955 0.95
2 0.95 0.895 0.865 0.845 0.83
3 0.51 0.38 0.3 - _
4 0.99 0.98 0.97 0.935 0.92
0.965 0.94 0.9 0.85 0.81
6 0.805 0.62 0.46
7 0.94 0.875 0.82 0.78 0.74
8 0.93 0.87 0.83
9 0.98 0.95 0.93 0.94 0.94
0.97 0.965 0.95 0.94 0.93
The data in Table 2 suggest that the chemicals of Examples 1, 4,
9 and 10 are reasonably stable under the test conditions, since
after 2 days exposure, better than 90% of the active material was
still present. The ch~;c~l~ of Examples 2, 5, 7 and 8 did
degrade, but after 1 day better than 80~ o~ the original active
material still remained. The chemicals of Examples 3 and 6
di~played significant degradation.
EXAMP~E 12
~h~r~-l Degradation Studies at 315~C under Air with 1010 ~ild
Steel
The method of Example 11 wa~ repeated, except that the mu~fle
furnace was set at 315~C for this series of runs. The infrared
frequencies cited in Table 1 were also used in the acquisition
of data for this series as well as those of Example 13, and the
normalized data appearing in Tables 3 and 4, respectively.
' ~
.' CA 02249171 1998-09-30
Table 3. Degradation Data of Various Chemicals at
315~C unde~ A;r with 1010 Mild Steel
Normalized Ratio (active/inactive)
Example
Number @ 5 hr~ 10 hr@ 20 hr@ 30 hr~ 40 hr
1 0.8 0.67 0.47 0.34 0.225
2 0.860.765 ~0.635 0.54
3 0.5050.35 0.235 - .
4 0.9750.955 0.905 0.86 0.83
0.9050.825 0.75
6 0.68 0.555
7 0.89 0.82 0.755 0.67 0.57
8 0.78 0.61 - - - .
9 0.95 0.925 0.88 0.83 0.78
0.93 0.91 0.88 0.82 0.745
The above data show that for the chemicals of Examples 4, 9 and .
10, good thermal stability can be realized; greater than 85~ o~ ,
the original active material is present after 24 hours under the
cited conditions. The chemicals of Examples 2, 5 and 7 are
considered to be marginal, while those of Examples 1, 3, 6 and-
8 display significant degradation.
EX~MPL~ 13
~h~ ~1 Degradation studies at 340~ under Air with 1010 ~ild
Steel
The method of Example 11 was repeated, but that the muffle -
furnace was set at 340~C for this series of runs. The nol ~li7-ed
data appear in Table 4.
' ' ' CA 02249171 1998-09-30
,
,
- Table 4. Degradation Data for Various Chemicals at
340~C under Air with 1010 Mild Steel
Nol 91- ~ed Ratio (active/inactive)
Example
Number @ 1 hr @ 4 hr @ 7 hr @ 10 hr~ 20 hr
1 0.7~ 0.47 0.33 - -
2 0.81 0.64 0.43 - -
3 0.61 0.4 0.33 0.27
4 0.87 0.805 0.71 0.67 0.555
, 5 0.97 0.82 0.7 0.62 0.41
6 0.42
0.92 0.71 0.595 0.505
8 0.84 0.64 - - -
9 0.965 0.835 0.715 0.675 - ~'
Ø97- 0.92' 0.87 0.825 0.67
The above data show that the chemicals from Examples 4, 5, 9 an~
10 are more thermally stabile under the reaction conditions than
the other materials. In these cases, better than 5'0~ of the
active material is present at 15 hours.
EX~MP~E l~A
~hermal Degradation Studies of 40% Active Synthetic Aromatic
Solven~ Materials at 340~C under Air with 1010 Mild Steel
One ml ampules were charged with 0.25 grams of 40% (by weight)
solutions cont~in;ng the chc~;c~l to be evaluated in synthetic
aromatic solvent (Alkylate 230, Monsanto), and 4 cm of 22 gauge
1010 mild steel wire. The ampules were then sealed under air,
and placed into a muffle furnace at 340OC. At various times,
some of the ampules were remov,ed, cooled and opened. The
contents were evaluated by infrared spectroscopy. As in Example
11, normalized ratios of absorb~nc~-~ for active to inactive
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~ ' CA 02249l7l l998-09-30
. ~ _
absorh~nc~s were det~rr;ned. Table 5 shows the ~re~uencies used
~or the chemicals evaluated, while Table 6 contains the
normalized data describing degradation.
Table 5. In~rared Frequencies ~or Evaluated Chemicals in
Solvent
. .
Example Number o~ Active Fre~uency Inactive Frequency
Chemical Evaluated (cm~l) (cm~l)
1 1600 1460
2 1600 1460
4 1635 1460
1640 1460
6 1635 1460
9 1640 1460
1630 1455
Table 6. Degradation Studies ~or 40% Active Solutions Oe
Various Chemicals at 340~ under Air with 1010 Mild Steel
Norma ized Ratio (act-ve/inac ive)
Example
Number @ 1 hr@ 2 hr @ 5 hr @10 hr@20 hr@50 hr
0.72 0.64 0.43 0.335 0.075
2 0.46 0.33 0.19 0.165 0.09
4 0.97 0.945 0.875 0.805 0.66 0.415
0.93 0.9 0.82 0.695 0.605 0.25
6 0.73 0.48 0.27 0.17 0.06
9 O.9Z 0.8 0.685 0.625 0.57 0.36
0.98 0.96 0.95 0.93 0.865 0.555
These data show that the chemicals of Examples 4 and 10 are the
most stable under these conditions. Chemicals prepared by
Examples not listed in Tables 5 and 6 were not evaluated since
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they are not soluble in the aromatic solvent; the chemicals
listed in Tables 5 and 6 can be formulated into heavy aromatic
solvent without using a cosolvent.
EXAMP~E 14B
Thermal Degradation Studies of 40% Active Synthetic Aromatic
Solvent Materials at 400~c under Air with 1010 Mild Steel
One ml ampules were charged with 0.25 grams of 40% (by weight)
solutions cont~; n i ng the chemical to be evaluated in synthetic
aromatic solvent (Alkylate 230, Monsanto), and 4 cm 22 gauge 1010
mild steel wire. The ampules were then sealed under air, and
placed into a muf~ie furnace at 400~C. At various times, some
of the ampules were removed, cooled, and opened. The contents
were analyzed by infrared spectroscopy. As in Example 11,
noL ~ ed ratios of absorbances for active to inactive
absorbances were det~rr;ned. The fre~uencies used for this
Example are those shown in Table 5 of Example 14A. srable 6.5
displays the normalized data which describe the degradation.
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t ,~ CA 02249171 1998-09-30
Table 6.5. Degradation Studie5 for 40% Active Solutions
o~ Various Chemicals at 400~ under Air with 1010 Mild Steel
Normalized Ratio (act ve/inactive)
Example
Number @O.lhr @0.2hr @0.4hr @0.6hr ~0.8hr *~1~ h~
1 0.76 0.6 0.320.22 0.14 0.07
2 0.8 0.6 0.370.32 0.17 0.01
4 o.99 0.98 0.860.71 0.56 0.4
o.g 0.78 0.580.41 0.28 0.15
6 0.58 0.15 0.1 0.06 0.05 0.04
9 0.87 0.77 0.520.34 0.23 0.12
~o ~ 0.96 0.92 0.820;68 0.51 0.34
'hese data suggest that chemicals 4 and lC are the ~ost stLble
under the reaction conditions.
EX~MPLE 15
Evaluation o~ Various Chemicals as Corrosion Inhibitors in
Rotating Wheel Test Using ASTM Brine and Crude Oil at 60~C ~or
24 hours with 1010 Mild Steel Coupons
A variation of NACE ID182, Item 54238, test for corrosion
inhibition was used to evaluate the chemicals of Example 1
through 10. Seven ounce glass bottles were charged with 50 ml
brine (ASTM D-1141) and 50 ml dehydrated California crude oil
(API gravity of 26.9~), and the appropriate amount of test
c-he ic~l (1% in xylenes). The brine was purged ~or 4 hours with
a stream of carbon dioxide gas. The bottles were sealed under
a ~our second purge o~ hydrogen sulfide gas (displacing nitrogen
overhead vapors), a~ter the addition of a cleaned, preweighed
1010 mild steel coupon. The bottles were placed on a rotating
wheel apparatus for 24 hours at an isothermal temperature of
60~C. Afterwards, the coupons were removed from the bottles,
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.
.
cleaned and reweighed. Untreated blank coupons were also run for
each wheel test group. The percent protection was then
calculated via the following fo~
% Protection = (100%)(B1ank Weight Loss - Test Coupon Weight Loss)
Blank Weight Loss
Table 7. Percent Protection for Various Chemicals
Percent Protection
Example Q @ ~ @ @
Number 3 ppm 10 ppm 25 ppm 50 ppm 100 ppm
76 79 83 85
2 55 62 71 74 82
3 56 63 74 78 81
4 57 63 67 77 84
47 53 61 73 84
6 46 46 46 49 51
7 46 48 53 57 59
8 .49 .55 ~58 61 62
9 52 61 68 72 83
49 50 59 68 75
The data in Table 7 show that the chemical in Example 1 gives
excellent protection to mild steel when it is not subjected to
high temperature degradation. Good protection is provided by the
chemicals oe Examples 2, 3, 4 and 9. Fair protection is provided
by the chemicals oE Examples 5 and lo at high use conc~ntrations.
Poor protection by the chemicals o~ Examples 6, 7 and 8 are
suggested by this test procedure.
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,
. . --
- EXAMPLE 16
Evaluation of Various Chemicals a~ter beinq Heat Treated at 315~C
The method of Example 15 was repeated, but by using the same
chemicals after they were exposed to 315~C for 24 hours in sealed
tubes. The results are displayed;in Table 8.
Table 8. Percent Protection for ~arious Heated Treated (315~)
Chemicals
Percent 'rotection
Example @ ~ @ ~ @
Number 3 ppm10 ppm 25 ppm50 ppm100 ppm
', 1 23 30 40 47 54
2 20 29 39 48 52
3 15 19 28 34 44
4 S1 60 65 72 77
44 51 56 68 74
6 19 18 25 30 35
7 20 26 35 40 55
8 8 21 25 30 38
9 49 55 62 68 75
43 53 66 71 76
The data in Table 8 show that the chemicals of Examples 4, 5, 9
and 10 provide good corrosion protection a~ter being subjected
to 315~C ~or 24 hours. The other chemicals display poor
protection to mild steel in this test condition.
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.
EXAMP~B 17
~valuation of Various Chemicals after beinq Heat Treated at 340~C
The method of Example 15 was repeated, except that the chemicals
to be evaluated were heated to 340OC for 24 hours in sealed
tubes. The data are shown in Table 9.
Table 9. Percent Protection for Various Heat Treated (340~C)
Chemicals
Percent Protection
Example @ @ @ ~ ~
Number 3 ppm10 ppm25 ppm50 ppm100 ppm
1 6 15 19 20 22
2 6 15 12 13 20
3 5 13 17 20 23
4 41 46 49 58 61
29 35 40 42 48
6 4 8 8 6 6
7 26 27 33 34 35
8 5 8 12 11 14
9 30 32 38 38 46
39 50 56 58 64
The data in Table 9 show that the chemicals of Examples 4 and 10-
provide good protection at average and high use concentrations.
The chemical~ o~ Examples 5, 7 and 9 show ~air protection at high
use concentrations, while the r~;n;ng chemicals provided poor
protection to lolO mild steel under the test conditions.
The aromatic aminoamide of Example 7 showed a slightly lower
protection than the cyclo~l;ph~tic aminoamides of Examples 5 and
9_ . .
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- CA 02249171 1998-09-30
The corrosion experiments show that aminoamides in line with the
general formula of the present invention have much higher
corrosion inhibiting efficiency than aminoamides with an aromatic
ring in the molecule, the special ~ ne of Example 3 and the
aminoamides with an imidazole ring.
EXAMPLE 18
Evaluation of Various Chemicals in a Sealed Autoclave at 320O
Under Pressure
A 800 m~ SS-316 autoclave (Parr Model 4841) was charged with 70
ml 6~ ASTM brine, 70 ml crude oil having an API gravity of 22.1~,
and a magnetic stirring bar. Preweighed and cleaned mild steel
1010 coupons were fitted to the lid of the autoclave so thàt when
sealed, the coupons were partially immersed within the stirred
fluids. When a test inhibitor was used in a run, it was injected
into the fluid mixture at 100 ppm using a micropipet. Once the
autoclave was sealed, it was pressured up to 500 PSIG with a
gaseous mixture containing 98.8% methane, 1.0% carbon dioxide,
and 0.2 hydrogen sulfide. The system was heated externally to
320OC, and held there for 24 hours. The resulting pressures were
recorded ~or the 320~C condition. Afterwards, the system was
cooled to room temperature, and opened. The coupons were
removed, cleaned, reweighed, and inspected. The results are
shown in Table 10.
,
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Table 10
Chemical System %
Evaluatea Pressure Protec~ion Comments
Discoloration and
Gunking, General and
2250 - Pitting Corrosion
Example 1 2440 PSIG 11.4 Observed
Example 4 2280 PSIG 41.6 General corrosion Seen
Slight Discoloration
and General
Example 5 2320 PSIG 33.3 Corrosion Seen
Example 10 2260 PSIG 44.6 General Corrosion seen
These results show the aminoamides o~ this invention give good
inhibition at high temperatures under pressure, and that typical.
imidazolines ~ail.
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