US2398202A - Anticorrosive - Google Patents

Description

Patented Apr. 9 1946 ANTICORROSIVE Ernest W. Zublin, Sausalito, Ellis R. White, Albany, and Emmett R. Barnum, Berkeley, Calif., asslgnors to Shell Development Company, San Francisco, Calil., a corporation oi Delaware No Drawing. Application February 8, 1943, Serial No. 475,198

19 Claims. (01. 252-56) 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 normallyliquid or normally solid hydrocarbons, alcohols, esters (e. g., fatty oils and natural waxes), water, etc., containing finely dispersed small amounts of certain free dicarboxylic acids in which the acid radicals are linked through one or more elements selected from the group consisting of sulfur, selenium and tellurium.

Metallic surfaces, particularly those containing iron, require protection against the hazard of corrosion in the presence of water. To illustrate: 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 corrodes closely fitted parts such as are found in Diesel engine unit type injectors; water in 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 effect upon the metal surfaces, but also frequently loosens finely divided metal oxides which may act as oxidation catalysts increasing the rate of detericration of various organic compounds with which they come in contact or may enter between moving parts of machinery where they act as abrasives.

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 composi-. tions, 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 metals and in general for protecting various metals against corrosion.

We have discovered that dicarboxylic acids having at least 16 carbon atoms in which the acid radicals are linked through a divalent sulfur, selenium or tellurium atom are such potent corrosion inhibitors that they are capable of effectively preventing rusting of ferrous metals and corrosion in general, affording protection not only and general corrosion prevention, small amounts of these acids are finely dispersed (as in true or colloidal solution) in a suitable vehicle. Inasmuch as many of them are quite soluble in many solvents, true solutions containing the necessary amounts can easily be prepared for most purposes.

The general formula of these acids is:

204-0 OOH (X wherein X is sulfur, selenium or tellurium, and u, v and w are integers, preferably 1 or 2. The unoccupied valences are tied to the same or different hydrogen or hydrocarbon radicals, the latter of which may be aliphatic, cycloaliphatic, aromatic or mixed and may contain substitution radicals which are not too strongly polar, such as halogen, etc., but should preferably be free from strong polar radicals, such as The above formula may take the following form:

As indicated before, the acid should'have a total number of carbon atoms not less than 16, and preferably between about 20 and for good anti-corrosive properties. Both true solutions and colloidal dispersons in various vehicles are effective in the matter of corrosion protection. However, true solutions are preferred for two reasons: first, colloidal solutions may under some circumstances coagulate, in which case at least a portion of the active protective agent is eliminated; and second, colloids tend to cause emulsification of oily vehicles with water, which in many instances, such as in the lubrication of steam turbines, is undesirable. It is, of course, desirable that the acids be relatively resistant to oxidation, and therefore they should not contain more than one aliphatic double bond per hydrocarbon radical and preferably none.

Generally, in the presence of copper. acids containing a link of a single x atom (X being S, Se or Te) seem to impart to oils longer induction periods than acids having X-X linkage, while the latter impart lower rates of oxygen absorption after the inductipn period. Thus disulfide, diselenide or ditelluride acids may be preferred for some oils, while acids with mono linkages may be better for other oils. more than two sulfur atoms may also be used. They are, however, believed to contain only two sulfur atoms in the normal chain between the carboxyl radicals, the remaining sulfur being attached in the form of a branch. such as s s I H --s-- s etc. If desired, the carboxyl radicals may be linked through a sulfone radical The closeness of the sulfur, selenium or tellurium to the carbowl radical has some bearing on. the corrosion-protective properties of the acids. In general, the closer they are, the more potent the compound is, other things being equal. Thus, from this angle, acids in. which the sulfur, selenium or tellurium atoms are in alpha or beta position to at least one, and preferably both carboxyl radicals are the best anticorrosives.

Accordingly, among the groups of acids are several which are particularly useful. For example, di-fatty acid alpha sulfides, selenides and tellurides having the formula Polysulfide linkages of radicals, the latter preferably being aliphatic although they may comprise cycloaliphatic or aromatic groups. The unoccupied valences are tied to hydrogen or hydrocarbon radicals, which groups. X again is sulfur, selenium or tellurium; n is preferably 1 or 2; and o is 1 or preferably 2. The total number of carbon atoms is preferably 20 or more.

The dicarboxylic acids of this invention may be produced in several ways. One convenient method comprises reacting a chlorinated fatty acid or other suitable monocarboxylic acid with an alkali metal sulfide or polysulfide. Commercially available alkali metal sulfides are usually mixtures containing mono-, diand sometimes higher polysulfides. Therefore this reaction may be utilized to produce mixtures of different sulfide dicarboxylic acids. Such mixtures are very excellent for the purpose of this invention, since they are usually more soluble in various vehicles and as oxidation stable as the best of the pure individual compounds.

Disulfides may be produced by first preparing a hydrosulfide derivative of a fatty acid or other suitable carboxylic acid by reaction of a chlorinated carboxylic acid with Nal-IS, KHS, etc.,

then oxidizing the hydrosulfide to the disulfide.

wherein o is l or 2, and R1 and Rs are alkyl mono-, diand higher polysulfides; di-phenylstearic acid alpha sulfides; dicyclohexyl-stearic acid alpha sulfides, di-petroleum naphthenic acids alpha sulfides, etc. Obviously, the two fatty or naphthenic acids linked by the sulfur may be difierent as, for example, in phenyl stearic acidacetic acid sulfides.

Groups of acids somewhat different from the above are represented by the formulae:

COR

Cmwi V (20011 coon wherein Rr-Ra are hydrogen or hydrocarbon alpha sulfides including both.

' Higher polysulfides may be obtained by oxidizing with sulfur in the presence of lead oxide.

Asymmetric dicarboxylic acids may be produced, for example, by reacting a suitable chlorinated monocarboxylic acid with an alkali metal salt of thioglycolic acid or of a fatty or other suitable monocarboxylic acid hydrosulfide.

Suitable monocarboxylic acids for the production of our dicarboxylic acids include fatty acids, such as acetic acid, propionic, butyric, isobutyric, valeric, caproic, caprylic, decylic, undecylic, lauric, myristic, palmitic, stearic, arachic, behenic, oleic, phenyl acetic, phenyl propionic, phenyl stearic, tolyl stearic, naphthyl acetic, naphthol stearic, acids, etc. Naphthenic acids, such as are obtained by caustic alkali extraction of relatively high-boiling straight-run petroleum etc., may be used; or synthetic naphthenic acids,

such as cyclohexyl acetic, cyclohexyl propionic, cyclohexyl stearic acids, corresponding alkyl cyclohexyl, tetrallyl, dicyclohexyl fatty acids, or acids derived from naphthenes obtained by hydrogenation of isophorone, diisophorone and homologues, etc. In choosing a monocarboxylic acid from the list for use in a certain reaction, sight must not be lost of the fact that the dicarboxylic acid must have a minimum of 16 carbon atoms.

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 -maybe accomplished by immersing, flooding,

. spraying, brushing, trowelling, etc.

After being applied, all or part of the vehicle- Q may be evaporated, or it may be more or less permanent. In other words, both volatile caraaeaaoa riers 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 preferably be substantially neutral, although it may be weakly acidic or basic, preferably having dissociation constants not above about In vehicles of low dielectric constant, as hydrocarbon oils, which are not conducive to ionization of dissolved electrolytes, relatively small amounts, i. 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, dlpropyl ketones, cyclohexanone and higher ketones; keto alcohols as benzoin, others as diethyl ether, diisopropyl ether, diethylene dioxide, beta-beta dichlor diethyl ether, diphenyl oxide, chlorinated cliphenyl oxide, diethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, corresponding ethyl, propyl, butyl ethers; neutral esters of carboxyiic and other acids as ethyl, propyl, butyl, amyl, phenyl, cresyl and higher acetates, propionates, butyrates, lactates, laurates, myristates, palmitates, stearates, oleates, ricincleates, phthalates, phosphates, phosphites, thiophosphates, carbonates; natural waxes as Carnauba wax, candellila 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, flaxseed oil, etc.; weak bases as pyridine, alkyl pyridines, quinolines, petroleum bases, etc.

Vehicles of little or no polarity comprise hydrocarbons or halogenated 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 soap-thickened to form greases), petrolatum, parafiin wax, albino asphalt, carbon tetrachloride, ethylene dichloride, propyl chloride, butyl chloride, chlor benzol, chlorinated parafiin wax, etc.

The amounts of the dicarboxylic acids which must be incorporated in the above vehicles to produce corrosion-protective compositions vary considerably with the type of vehicle used. As a general rule, thepresence 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, phenol-formaldehyde resins, glyptal type resins formed 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 .00l% up to about .l%, although larger amounts may be used. However, where the acids are in colloidal dispersion, rather than chlorinated kerosene,

in true solution, a concentration in excess of about .l% may result in relatively quick loss of part or the inhibitor by precipitation and settling.

In the presence of resins and other colloids,"

amounts in excess of .l% and up to 5% may be 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-dichlorine diethyl ether, antimony trichloride, etc.; treatment with AlCls, sulfuric acid, clay, etc. If the treatment produces a sludge, special care must be taken to remove it very thoroughly and completely.

Applications of the various corrosion-protective compositions vary over a wide range. Hydrocarbon compositions are of special importance. For example, gasoline's 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.

Diesel fuels may cause corrosion of injection nozzles.

Lubricating oils and greases made of lubricating oils and soaps normally allow corrosion or even may cause corrosion of various metal parts with which they come in contact, such as bearings, crank-cases, shafts, etc. This problem arises in many types of engines and is often particularly serious in steam turbines. The presence of the inhibitors of this invention will afford excellent 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 oilscomprising various types of liquid or plastic hydrocarbons, fats, waxes, lanolin, 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. I

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

Among the non-hydrocarbon compositions which frequently cause corrosion difiiculties, antifreezes used in automobile radiators and the like may be mentioned. The dicarboxylic acids effectively eliminate their corrosiveness. Antifreezes usually comprise or consist of water-miscible 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 of this invention.

Dispersions of the dicarboxylic (ll-fatty acids in water may be useful in the rust-proofing of by the acids We claim as our invention:

1. A corrosion-preventive composition comprising predominantly an oleaginous vehicle containing finely dispersed a small corrosion inhibitmetals which after treatment must not be greasy ing amount of a dicarboxylic acid having at least as, for example, various machine parts in the 16 carbon atoms, the two acid radicals in said textile industries, particularly in the knitting of acid being linked through an element selected fine dry goods. If desired, solutions or disperfrom the group consisting of S, Se, and Te, said sions in low-boiling alcohols, etc., may be used element being attached to a carbon atom not for the same purpose. it) further removed from the carboxyl radical than It is understood that the corrosion-protective the beta position. compositions of this invention may contain other 2. The composition of claim 1 wherein the ingredients in addition to the vehicle and the number of carbon atoms in said acid is between dicarboxylic acids, However, such additional innd 60.- gredients must be chemically inert to the acid 16 h Composition of aim 1 e ein sa and the vehicle employed. Thus strong oxidizing acid i in c l l al solution. agents as chlorine, peroxides, etc., must be avoid- A cormsiompr-evenfive compositlon ed as they tend to destroy the inhibitors. Strong lmsing predominantly n oleasinous vehicle 9 bases, particularly in ionizing vehicles, as m talning finely dispersed a small corrosion inhibitwater, alcohols, etc., will neutralize the diacids 20 s amount of dicarboxylic id having at least and thereby render them relatively ineffective. 15 carbon awms am1 having the formula Likewise, strong acids may reduce their eifecw tiveness. However, in non-ionizing solvents, i. e., P0003 in hydrocarbon compositions, chlorinated hydrox v carbons, etc., the presence of relatively small a quantities of primary, secondary and tertiary K nitrogen bases and/or carboxync acids Wm wherein X is an element selected from the roup normally interfere with the activity of the inhibconslstm g of S, Se and Te, 14 and v are each initor. On the other hand, even in these vehicles 3o tegers of less than three, and w is equal to one. very strong bases as various onium bases, or very t id If i 01 d should not be 5. A corrosion-preventive composition coms ac S as on c a prising predominantly an oleaginous vehicle confs d1 1 h d be m a th tainin a small corrosion inhibiting amount of a ng n compos ons an e dicarboxylic acid having at least 20 carbon atoms like may contain various types of omdation inand the i0 1 5 Imu a hibitors as alkylated phenols, aromatic amines, C 0 preferably secondary amines, amino phenols; as H C OH well as various EP compounds containing halo- )0 gen, S, P, As, etc., anti-wear compounds, de- MAE-{F0005 tergents, sludge-preventing compounds, pour point reducers, thlckeners such as soaps, etc. z i R2 are z f a g hycglocmbon Likewise, fats, anti-freezes, etc., may contain m P s an elemen Se ec 8 mm 9 group antboxidants. consisting of S, Se, and Te, and o is 1 or 2.

Examples 6. A corrosion-preventive composition comprising predominantly a substantially neutral The effectiveness of several dicarb yli acids oleaginous vehicle containing finely dispersed a of this invention in suppressing corrosion was desmall corrosion inhibiting amount of a dicarboxtermined,by a test which consists of subjecting ylic acid having at least 20 carbon atoms, the two a polished steel strip to the action of a vigorously carboxylic acid radicals in said acid being linked stirred emulsion of a turbo ramnate of 150 S. U. through a single divalent sulfur atom in alpha viscosity at 100 F. with 10% by volume of water position with respect to each of said carboxylic at 167 F. In some cases, distilled water was acid radicals. used, in others a 2% solution of NaCl, or sea '7. A corrosion-preventive composition comwater from the Pacific Ocean, or a synthetic sea prising predominantly an oleaginous vehicle conwater which had the same analysis as real sea taining finely dispersed a small corrosion inhibitwater, When using distilled water protection was ing amount of di-stearic acid alpha, alpha monoperfect in all cases for more than 48 hours. Brine sulfide. waters gave the following results: 8. A corrosion-preventive composition com- Additive 1 Water Time Corrosion Hours .0191, alpha alpha dilauric acid sulfide 2% NaOl 48 None-perlcct protection.

Synthetic sea water. 48 Do.

.0l% alpha alpha dimyristic acid sulfide 2% NaCl 24 None-perfect protection.

Seawater 25 Perfect. Synthetic sea water. 48 Do.

.Ol% alpha alpha dipalmitic acid sulfide Synthetic sea water... 48 Perfect.

.0l% alpha alpha distearic acid sulfide 2% NaCl 48 Perfect.

Do Sea water 44 Slight corrosion, less than 10%. Do Synthetic sea water... 48 Noneperfect protection. .005% alpha alpha distearic acid sulfide .do 25 Slight corrosion, less than 10%.

.Ol% alpha-lauric alpha-stearic acid sulfide Synthetic sea water 48 Noneperlect protection.

.0l% alpha alpha distearic acid dlsulfide 2% N aCl 48 Perfect.

. Synthetic sea water... 24 Very slight corrosion.

.0l% alpha hexadecyl thicglyoolic'acid 2% NaCl 24 Very slight corrosion.

prising predominantly an oleaginous vehicle containing finely dispersed a small corrosion inhibitingamount of di-myristic acid alpha. alpha mono-sulfide.

9. A corrosion-preventive composition comprising predominantly an oleaginous vehicle con-- taining finely dispersed a small corrosion inhibiting amount of di-palmitic acid alpha, alpha mono-sulfide.

10. 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, the two acid radicals in said acid being linked through an element selected from the group consisting of S. Se or Te, said element being attached to a carbon atom not further removed from the carboxyl radical than the beta position.

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

12. The composition of claim 10 in which said substance is normally plastic.

13. 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, the two acid radicals in said acid being linked through an element selected from the group consisting of S, Se or Te, said element being attached to a carbon atom not further removed from the carbonyl radical than the beta position.

14. A corrosion-preventive composition comprising predominantly a substantially neutral oleaglnous substance containing resins-and finely dispersed .l%-5% of a free dicarboxylic acid having at least 16 carbon atoms, the two acid radicals in said acid being linked through an element selected from the group consisting of S, Se or Te, said element being attached to a carbon atom not further removed from the carboxyl radical than the beta position.

15. A corrosion-preventive lubricating oil containing finely dispersed .001%-1% of a free dicarboxylic acid having at least 16 carbon atoms. the two acid radicals in said acid being linked through an element selected from the group consisting of S, Se or Te. said element being attached to a carbon atom not further removed from the carboxyl radical than the beta position.

16. 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, the two acid radicals in said acid being linked through an element selected from the group consisting of S, Se or Te, said element being attached to a carbon atom not further removed from the carboxyl radical than the beta position.

17. 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, the two acid radicals in said acid being linked through an element selected from the group consisting of S. Se or Te, said element being attached to a carbon atom not further removed from the carboxyl radical than the beta position.

18. A noncorrosive 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, the two acid radicals in said acid being linked through an element selected from the group consisting of S, Se or Te, said element being attached to a carbon atom not further removed from the carboxyl radical than the beta position.

19. A corrosion-preventive composition comprising predominantly an oleaginous vehicle containing finely dispersed a corrosion-inhibiting amount of a di-fatty acid having at least 20 carbon atoms, the two acid radicals in said acid being linked through a single divalent sulfur atom between two carbon atoms not further removed from each of the acid radicals than the beta position.

ERNEST W. ZUBLIN. ELLIS R. WHITE. EMME'II R. BARNUM.