US2371142A - Anticoerosive - Google Patents

Description

Patented Mar. 13, 1945 ANTICOBBOSIVE Emmett R. Barnum, Berkeley, and Ernest W. Zublin, Sausalito, Callf., assignors to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application February 8, 1943, Serial No. 475,201

24 Claims.

The present invention relates to compositions having anti-corrosive, and especially rust-protective, properties, and more particularly deals with compositions comprising a substantially neutral vehicle, such as normally liquid or nor= mally solid hydrocarbons, alcohols, esters (e. g., fatty oils and natural waxes) water, etc., containing finely dispersed small amounts of certain free dicarboxylic acids.

Metallic surfaces, particularly those containing iron, require protection'against the hazard of corrosion in the presence of water. Moisture readily attacks finished or semi-finished metal objects unless the metal surface is covered during storage or shipment by a protective coating such as a slushing oil; water in Diesel engine fuels often corrodesclosely fitted parts such as are found in Diesel engine unit type injectors; waterin turbines corrodes turbine lubricant circulatory systems, particularly the governor mechanisms of steam turbines; and water in hydrocarbon oils such as gasoline rusts steel storage tanks and drums; water in anti-freeze compositions causes corrosion in automobile radiators, etc. Corrosion not only has a deleterious efiect upon the metal surfaces, but also frequently loosens finel divided metal oxides which may act as oxidation catalysts increasing the rate of deterioration of various organic compounds with which they come in contact or may enter between moving parts of machinery where they act as abraslves.

It is a purpose of this invention to produce potent corrosion-protective compositions of wide applicability. Another purpose is to produce slushing compositions of improved corrosion-protective properties. A specific purpose is to produce rust-protective hydrocarbon compositions, i. e., including various Diesel oils, steam turbine oils, greases, etc. Still another purpose is to provide anti-freeze compositions free from a tendency to cause rusting. Further, it is a purpose to produce a non-oily composition which can be used for rust-protection of ferrous metal and in general for protecting various metals against corrosion.

We have discovered that dicarboxylic acids having at least 16 carbon atoms in which there is an ether type radical of an element selected from the group consisting of oxygen, sulfur, selenium and tellurium close to at least one and preferably both carboxyl radicals, which radical branches from the carbon chain linking .the car- To illustrate:

looxyl radicals, are such potent corrosion inhibitors that they are capable of effectively preventing rusting of ferrous metals affording pmtection not only against pure water, but against etc.

The general formula of our acids may be represented as follows:

coon

((RX'(CH1)I)) 0-0 u OOH wherein u is an integer from 1 up to about 8 and preferably 2, v is an integer from zero up to about 8, preferably zero, w is at least 1, preferably 1 or 2,v

and never greater than u, X is an element of the class 0, S, Se or Te, and R is a hydrocarbon rad-' ical. Unoccupied valences may be tied to the same or different hydrogen or hydrocarbon radicals.

The several hydrocarbon radicals may be allphatic, alicyclic, aromatic or mixed and may contain substituents which are preferably not too strongly polar, such as halogen, but are preferably free from highly polar substituents, such as hydroxyl, carboxyl, carbonyl, amino, hydrosulfide, etc. For maximum stability against deterioration by oxidation, the acid should contain not more than one aliphatic double bond per hydrocarbon radical, and preferably none.

As indicated above, the acid should contain not less than 16, and preferably at least 20 and up to 60, carbon atoms for good anti-corrosion properties. Also, the closeness of the 0, S, Se or Te, as the case may be, to the carboxyl radicals has a bearing on this property, in general the closer they are, the greater the protective power. Because of this, homologues in which the ether linkage is in alpha or beta position to at least one and preferably both carboxyl radicals are most desirable.

The simplest of these acids are the malonic acid derivatives illustrated below:

wherein again X is O, S, Se or Te and R is a hydrocarbon radical. However, this type of acid is thermally quite unstable, easily losing CO1. Therefore, for many purposes it is not desirable. succinic or fumaric (maleic) acid ether type derivatives, of which there are several, are very stable. i'hey are:

may of these is very effective.

There are many derivatives of glutonic acid,

a few of which are shown below:

ax-orr-coon Hr-COOH cm-coon RX- H Hz-COOH BX-CH-COOH RX- H CH-COOH nx-on-coon H nx-erbcoon From the above it can be readily seen what forms the dicarboxylic acid ethers may take, in which acids the carboxyl radicals are separated by four and more carbon atoms.

Where X stands for sulfur, two sulfur atoms may form the linkage. In other words, compounds of the following types are included in this invention:

R s s-cn-c on rr-coon R s SCH-C oon R s s-cn-oo on As may be noted, there are two general groups of dicarboxylic acids among those listed above, those containing a single ether type radical and those containing two ether type radicals. Under many circumstances, the acids containing two ether type radicals are preferred because they have -the ability of giving material corrosion protection in stagnant salt water. A form of corrosion which is probably most difficult to inhibit is that caused by a drop of salt water resting' undisturbed on a metal surface. Few, if any, corrosion inhibitors which are not of the soap type are capable of effectively preventing this corrosion. However, the bis-ether type acids and particularly the his sulfides of this invention have been proven to prevent corrosion against stagnant salt water for several days.

The compounds of this invention are quite soluble in many organic solvents. Wherever possible, true solutions are employed in preference to colloidal solutions for two reasons: first, because colloids tend to cause emulsiflcation of oleaginous substances with water; and second, colloids may precipitate, in which case at least a portion of the active ingredients would be lost.

The manufacture of most of the compounds of this invention is quite simple. For example, fumaric acid or maleic acid anhydride may be brominated and the resulting dibrom succinic acid is then reacted with an alcoholate, alkyl phenolate, mercaptide, selenide, telluride, etc., having a hydrocarbon radical of sumcient number of carbon atoms to insure that the reaction product has the required minimum of 16 carbon atoms. This hydrocarbon radical may be normal and/or cyclic, examples being heptyl, methyl cyclohexyl, normal or branched octyl, dimethyl cyiclohexyl, ethyl cyclohexyl, nonyl, decyl, undecyl, dodecyl, lauryl, myristyl, cetyl, stearyl, oleyl, arachyl, benzyl, methyl phenyl, ethyl phenyl, dimethyl phenyl, propyl phenyl, butyl phenyl, octyl phenyl, naphthyl, alkyl naphthyl, tetrahydronaphthyl, C10 and higher dialicyclic', etc.

The vehicles to which dicarboxylic acids of this invention may be added for the purpose of producing corrosion-protective compositions may be divided into several groups. In the first place, they may be liquids or plastics, the only requirements as to their physical state being (in addition to their being able to act as carrier for the acids under normal atmospheric conditions) that they be spreadable over metal surfaces. Spreading may be accomplished by immersing, flooding, spraying, brushing, trowelling, etc.

After being applied, all or part of the vehicle may be evaporated, or it may be more or less permanent. In other words, both volatile carriers may be used, or substances which do not materially volatilize under normal atmospheric conditions. As to chemical requirements, the vehicle must be stable under ordinary conditions of storage and use and be inert to the active inhibitors.

Thus the vehicle should referably be substantially neutral, although it may be weakly acidic or basic, preferably having dissociation constants not above about 10 In vehicles of low dielectric constant, as hydrocarbon oils, which are not conducive to ionization of dissolved electrolytes. relatively small amounts, 1. e., about .l%-5% of various carboxylic acids, such as fatty or naphthenic acids, may be present, and in many instances this may even be beneficial.

Both polar and non-polar vehicles may be employed. .Among the former are water, alcohols, such as methyl, ethyl, propyl, isopropyl, butyl, amyl, hexyl, cyclohexyl, heptyl, methyl cyclohexyl, octyl, decyl, lauryl, myristyl, cetyl, stearyl, benzyl, etc., alcohols; polyhydric alcohols as ethylene glycol, propylene glycol, butylene glycol, glycerol, methyl glycerol, etc.; phenol and various alkyl phenols; ketones as acetone, methyl ethyl ketone, diethyl ketone, methyl propyl, methyl butyl, dipropyl ketones, cyclohexanone and higher ketones; keto alcohols as benzoin, ethers as diethyl ether, disisopropyl ether, diethylene dioxide, beta-beta dichlor diethyl ether, diphenyl oxide, chlorinated diphenyl oxide, diethylene glycol, triethylene glycol, ethylene glycol monomenthyl ether, corresponding ethyl, propyl, butyl others; neutral esters of carboxylic and other acids as ethyl. propyl, butyl,

amyl, phenyl, cresyl and higher acetates, propionates, butyrates, lactates, laurates, myristates, palmitates, stearates, oleates, ricinoleates, phthalates, phosphates, phosphites, thio-phosphates, carbonates; natural waxes as carnauba wax, candelilla wax, Japan wax, jojoba oil, sperm oil; fats as tallow, lard oil, olive oil, cottonseed oil, Perilla oil, linseed oil, tung oil, soya bean oil, fiaxseed oil, etc.; weakibases as pyridine, alkyl pyridines,'quinolines, petroleum bases, etc.

Vehicles of little or no polarity comprise hydrocarbons, hydrocarbons as liquid butanes, pentanes, hexanes, heptanes, octanes, benzene, toluene, xylenes, cumene, indene, hydrindene, alkyl naphthalenes; gasoline distillates, kerosene, gas oil, lubricating oils (which may be soapthickened to form greases), petrolatum, paraffin wax, albino asphalt, etc.

The amounts of the dicarboxylic acids which must be incorporated in the above vehiclesto produce corrosion-protective compositions vary considerably with the type of vehicle used. As a general rule, the presence of resinous materials, particularly those of a colloidal nature, calls for relatively larger amounts of inhibitors. Resinous materials which interfere with the activity of the inhibitors comprise asphaltenes, petroleum resins, various other natural resins, as rosin, resins formed .by polymerization of drying fatty oils,

phenolformaldehyde resins, glyptal type resinsformed by esterification of polyhydric alcohols with polycarboxylic acids, etc.

In the absence of such resinous materials,

amounts required of the dicarboxylic acids vary from about .001%up toabout .1%, although larger amounts may be used. However, where the acids are in colloidal dispersion, rather than in true solution, a concentration in excess of about .1% may result in relatively quick loss ,of part of the inhibitor by precipitation and settling.

In the presence of resins and other colloids, amounts in excess of .1% and up to 5% may be a required. Inasmuch as resins may act as protective colloids, compositions containing these large amounts of colloidally dispersed inhibitors, together with resin, may be quite resistant to precipitation and settling.

Since resinous and gummy substances in the vehicles do call for greater amounts of inhibitors, it is usually desirable to refine normally liquid vehicles thoroughly and free them from gummy substances, thereby imparting to them maximum inhibitor susceptibility. This is of particular importance, for example, in lubricating oils, specifically steam turbine oils, which are advantageously highly refined before the inhibitor is introduced; Suitable refining treatments include, for example, extraction with selective solvent for aromatic hydrocarbons as liquid S02, phenol, furfural, nitrobenzene, aniline, betabeta-dichloro diethyl ether, antimony trichloride, etc.; treatment with AlCls, sulfuric acid, clay, etc.; as the treatment produces a sludge, special care must be taken to remove itvery thoroughly and completely.

Applications of the various corrosion-protective compositions vary over a wide range. Hydrocarbon compositions are of special importance. For example, gasolines stored in drums may cause rusting of the drums because of the accumulation of water. This is particularly bad in tropical countries where the moisture content of the air is high, and wide variations in temperature over a 24-hour cycle cause considerable breathing of the drums.

cellent protection in all of the above instances.

Rusting of ferrous metals exposed to the atmosphere during usage or storage is a serious problem. This is of particular importance where accurately machined parts must be preserved. Slushing oils comprising various types of liquid or plastic hydrocarbons, fats, waxes, lanolins, are employed to protect the metals against this attack, and the inhibitors of this invention have great value as an active component in such slushing oils.

Internal corrosion of ferrous metal pipe lines which transport hydrocarbons has been a matter of much concern, and the presence of small amounts of the dicarboxylic 'acids of this invention (especially those having two ether-type radicals) in hydrocarbon oils, particularly refined light hydrocarbon oils such as gasoline, greatly retards or fully prevents pipe line corrosion.

Cutting oils, EP lubricants, due to their content of sulfur and/or chlorine in various active forms, frequently are quite corrosive. The discarboxylic acids eifectively inhibit this corrosion.

Among the non-hydrocarbon compositions which frequently cause corrosion difliculties, anti-freezes used in automobile radiators and the like may be mentioned. The dicarboxylic acids effectively eliminate their corrosiveness. Anti-freezes usually comprise or consist of watermiscible alcohols, such as methanol, ethanol, isopropanol, glycol, glycerol, etc.

So-called hydraulic oils, damping oils, etc.,

which frequently are based on non-hydrocarbon liquids, such as various alcohols, esters, etc., have in the past introduced some corrosion difliculties which can effectively be prevented by the acids of this invention.

Dispersions of the dicarboxylic di-fatty acids in water may be useful in the rust-proofing of metals which after treatment must not be greasy as, for example, various machine parts in the textile industries, particularly in the knitting of fine dry goods. If desired, solutions or dispersions in low-boiling alcohols, etc., may beused for the same purpose.

It is understood that the corrosion-protective compositions of this invention may contain other ingredients in addition to the vehicle and the dicarboxylic acids. However, such additional ingredients must be chemically inert to the acid and the vehicle employed. Thus strong oxidizing agents as chlorine, peroxides, etc., must be avoided as they tend to destroy the inhibitors. Strong bases, particularly in ionizing vehicles. as in water, alcohols, etc., will neutralize the di-acids and Examples The effectiveness of dicarboxylic acids of this invention in suppressing corrosion was determined by a modified testflwherein a polished steel strip was subjected to the action of a vigorously stirred emulsion of a turbo raflinate having S. U. viscosity at 100 F. of 150 seconds with by volume sea Water at 167 F. Below are some typical results:

Additive Water Time Corrosion Hours .01% alpha beta Synthetic sea 48 Noneperfect dilauric dith io water. protection. succinic acid Distill e at 48 P r ct Mono thio lauryl e w e succinic gen {8 yvigttell etic sea 16 Partly corroded.

1 After the test was completed, stirring was discontinued and the steel strip was allowed to drop into the sea water at the bottom of the container, remaining there undisturbed for four days. At the end of this period, only a few small rust spots had developed.

We claim as our invention:

1. A corrosion-preventive composition comprising predominantly a stable, substantially neutral and chlorine free vehicle containing finely dispersed a small corrosion inhibiting amount of a free dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radiing predominantly a stable, substantially neutral and chlorine-free vehicle containing finely dispersed a small corrosion inhibiting amount of a succinic acid ether having at least 16 carbon atoms, which ether radical branches from the carbon chain linking the carboxyl radicals.

10. A corrosion-preventive composition comprising predominantly a stable, substantially neu- 1y dispersed a corrosion-inhibiting amount of a cal branches from the carbon chain linking the carboxyl radical.

2. The composition of claim 1 wherein the number of carbon atoms in said acid is between 20 and 60.

3. The composition of claim 1 wherein said vehicle has a dissociation constant below 10-.

4. The composition of claim 1 wherein said acid is in'truesolution.

5. The composition of claim 1 wherein said acid is in colloidal. solution.

6. A corrosion-preventive composition comprising predominantly a stable, substantially neutral hydrocarbon vehicle containing finely dispersed a small corrosion inhibiting amount of a free dicarboxylic acid having at least 16 carbon, atoms and having the formula coon ((R-X(cH,).) t-( wherein u is an integer of 1 up to about 8, v is an integer of from 0 to about 8, w is at least 1 and not greater than u, X is an element selected from the group consisting of O, S, Se and Te, and R is a hydrocarbon radical, and the unoccupied valences are tied to hydrogen or hydrocarbon radicals.

7. The composition of claim 6 where u and w are 2 and v is 0.

8. The composition of claim 6 wherein said vehicle comprises mineral oil.

9. A corrosion-preventive composition compris succinic acid disulfide having at least 16 carbon atoms.

12. A corrosion-preventive composition comprising predominantly a stable, substantially neutral chlorine-free vehicle containing finely dispersed a small corrosion inhibiting amount of a free dicarboxylic acid having at least 16 carbon atoms and having the formula wherein X is an element selected from the group consisting of O, S, Se and Te, and R is a hydrocarbon radical.

13. A corrosion-preventive composition comprising predominantly a. substantially neutral oleaginous substance containing a small corrosion inhibiting amount of a free dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

14. The composition of claim 13 in which said substance is normally liquid.

15. The composition of claim 13 in which said substance is normally plastic.

16. A corrosion-preventive composition comprising predominantly a substantially neutral oleaginous substance free from resins containing finely dispersed .001 %.1% of a free dicarboxylic acid having at least 16 carbon atoms, and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

17. A corrosion-preventive composition comprising predominantly a substantially neutral oleaginous substance containing resins and finely dispersed .1 %-5% of a free dicarboxylic acid having at least 16 carbon atoms and possessing at lease one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

18. A corrosion-preventive lubricating oil containing finely dispersed .001%-.1% of a free dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

19. A corrosion-preventive composition comprising predominantly a carboxylic acid ester containing finely dispersed a small corrosion inhibiting amount of a tree dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

20. A corrosion-preventive composition comprising predominantly a fat, and finely dispersed therein a small corrosion inhibiting amount of a free dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from thecarbon chain linking the carboxyl radicals.

21. A non-corrosive anti-freeze composition comprising predominantly a water-soluble alcohol and finely dispersed therein a small corrosion inhibiting amount of a free dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting of O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

22. The process of inhibiting internal corrosion in a ferrous metal pipe line carrying refined light hydrocarbon oil comprising passing through the pipe line said liquid hydrocarbon containing between .001% and .1% of a free dicarboxylic acid having at least 16 carbon atoms and possessing at least one ether-type radical of an element selected from the group consisting 01 O, S, Se and Te, which ether-type radical branches from the carbon chain linking the carboxyl radicals.

23. A corrosion-preventive composition comprising predominantly a stable, substantially neutral and chlorine-free vehicle containing finely dispersed a corrosion-inhibiting amount of a free dicarboxylic acid having at least 16 carbon atoms. and having the formula wherein X is an element selected-from the group consisting of O, S, Se and Te and R is a hydrocarbon radical.

24. A corrosion-preventive composition comprising predominantly a stable, substantially neutral vehicle containing finely dispersed a small corrosion inhibiting amount of a tree dicarboxylic acid having at least 16 carbon atoms and having the formula n-x-on-coon Hi-COOH wherein X is an element selected from the group consisting of O, S, Se and Te and R is a hydrocarbon radical.

EMME'I'I. R. BARNUM. ERNEST W. ZUBLIN.

Certificate of Correction Patent No. 2,371,142.

March 13, 1945'.

EMMETT R. BARNUM ET AL.

It is hereby certified that-error appears in the printed specification of the above numbered patent reqmring correction as follows: Page 1, second column, lines 13 to 18 inclusive, strike out the formula and insert instead the followingand that the said Letters Patent should be read with this correction th th t t same may conform to the record of the case in the Patent Office. 6mm a he Signed and sealed this 3rd day of July, A. D. 1945.

[SEAL] LESLIE FRAZER, Acting Uommissioner of Patents.