US2450807A - Rust preventive chromium compounds and compositions containing them - Google Patents

Description

Patente i1 uNi an STATES PATENT race nusr PREVENE CHROMIUM coM- roorms .anc comrosrrrons con- "IAINING THEM No Drawing. Application July 16, 1946, Serial No. 683,991

15 Claims.

This invention relates to the prevention of corrosion of metals, and in particular concerns new compositions of matter adapted to inhibitor prevent the corrosion or rusting of metal surfaces when applied thereto in the form of a coating.

In the shipping and storage of metal articles, particularly ferrous metal articles having me.- chined surfaces, it is highly desirable to protect such articles from the corrosion or rusting which normally occurs when metal surfaces are exposed to the atmosphere for any length of time. While such protection should remain eife'ctive over long periods of time under very adverse conditions of humidity. it should likewise be of such nature that.

it can readily be removed when it is desired to place the metal article into use. Among the various means employed for providing such protection against corrosion, that of applying a, film or coating of a non-corrosive liquid coating composition to the metal surface has enjoyed widest use by reason of its economy and ada tab lity to all sorts of metal articles ranging from sim le pieces to complicated machine assemblies. Such liquid corrosion preventive compositions often comprise a mineral, or other non-drying oil base having a corrosion preventive material dispersed or dissolved therein. and are hence usually referred to generically as slushing olls even though in some instances they may not actually contain anoil.

The slushing oils heretofore employed, however, have been subject to numerous disadvamta es. In some instances they have be n too expensive for widespread general use. whereas in others they are too difllcult to remove from surfaces to which they have been applied. Many of them .have not proved efiective over sufficiently long periods of time, or have not provided the desired protection against corrosion under extreme climatic conditions such as those encountered in the tropics or at sea.

Accordingly, it is an object of this invention to provide new corrosion preventives capable of use in inhibiting or preventing the corrosion or rusting of metal surfaces overlong periods of time and under adverse climatic conditions.

Another object is to provide corrosion preventives which can readily be dissolved or dispersed in a suitable liquid vehicle to form inexpensive and highly efiective slushing oil compositions.

A further object is to provide improved slushing oil compositions.

A still further object is to provide highly efficient slushing oil compositions adapted for ready 5 application and removal from all types of metal articles.

Other objects will be apparent from the following detailed description of the invention, and various advantages not specifically referred to herein will occur to those skilled in the art upon employment of the invention in practice.

I have found that the above objects and attendant advantages may be realized in certain new corrosion preventives obtained'as products of reaction between chromium trioxide and certain substituted oxazoline compounds. More particularly, I have found that products having excellent inhibiting action on the corrosion of metals may be obtained. by reacting chromium trioxide with an oxazoline compoundhaving the general wherein R represents the hydrocarbon residue of a fatty or naphthenic acid or of an acidderived from the oxidation of petroleum products; Y and naphthenic acid or of an acid derived from the oxidation of petroleum products as herein employed refers to the non-carboxylic, or hydrocarbon,portion of fatty, naphthenic, or oxidized petroleum acids of the formula R-COOH. Examples of such oxazoline compounds include 2- oleyl-2-oxazoline, 2-oleyl-4-methyl 4 hydroxymethyl-Z-oxazoline, 2-heptadecyl 4,4-cliethyl-2- oxazoline', 2 -undecyl 4-propyl-4-ethyl-5 methylz-oxazoline, 2-pentadecyl-4-butyl-2 -oxazo1ine, 2

heptadecadienyl-4-i sopropyl-4-hydroxymethyl-2- oxazoline, 2-dodecyl-4-hydroxybutyl-2-oxazoline, 2 oleyl-4.4,5-trimethyl-2-oxazoline, and analogous oxazoline compounds in which the substituo ent in the 2-position is the hydrocarbon residue of a naphthenic acid or an acid derived from the oxidation of petroleum products. The latter acids are high molecular weight saturated aliphatic carboxylic and hydroxycarboxylic acids obtained in admixture with hydrocarbons, aliphatic alcohols and ketones, and keto-alcohols by partially oxidizing petroleum hydrocarbons in the liquid phase at elevated temperatures and pressures as disclosed, for exam le, in U. S. Patents Nos. 1,690,768 and 1,690,769.

Such substituted oxazolines may be prepared in a number of ways, one of the most convenient of which consists in reacting a fatty r naphthenic acid, or an acid derived from the oxidation of petroleum products, with a beta-amino-alcohol with the elimination of two molecules of water. This reaction may be described by the equation:

wherein R, Y, Y, and Y" have the meanings hereinbefore defined. This reaction takes place readily, and can be effected simply by heating an equimolecular mixture of the two reactants to a temperature at which water distills from the mixture. If desired, an inert solvent, such as benzene or toluene, may be employed to facilitate the vaporization and removal of water from the reaction as an azeotropic mixture. Upon completion of the reaction, as evidenced by two mols of water having been distilled off, the reaction mixture may be washed and/or distilled under vacuum to recover and purify the oxazoline product. 4

Any fatty acid, particularly a higher fatty acid containing from 10 to '20 carbon atoms, such as oleic acid, linoieic acid, stearic acid, palmitic' acid, lauric acid, arachidic acid, or mixtures thereof such as are obtained from natural products, a naphthenic acid, or an acid derived from the oxidation of petroleum, may be employed as the acid reactant, and any compound of the formula wherein Y, Y and Y" have the meanings hereinbefore defined, may be employed as the betaamino-alcohol reactant. Thus, oleic acid may be reacted with 2-amino-Z-ethyl-propanediol- 1,3 to form 2-oleyl-4-ethyl-4-hydroxymethyl-2- oxazollne, myristic acid may be reacted with 2- amino-ethanoi to form 2-tridecyl-2-oxazoline, llnoleic acid may be reacted with 2-amino-2- propyl-butanediol-L4 to form Z-heptadecadienyl- -propyl-4-hydroxyethyl-2-oxazoline, lauric acid may be reacted with 1-amino-1-ethyl-1-propylisopropanol to form 2-undecyl-4-ethyl--propyl- 5-methyi-2-oxazoline, etc.

The oxazoline compounds of the present class may likewise be prepared by reduction and dehydration of the appropriate nitro-alkylol esters by a process similar to that disclosed in U. S. Patent 2,372,409.

The reaction between chromium trioxide and theherein defined substituted oxazolines to form the products which are employed as corrosion preventives in accordance with the invention is carried out by heating the oxazoline compound with between about 5 and about '25, preferably between about 8 and about 12, per cent by weight thereof of chromium trioxide. The latter is conveniently employed in the form of a 10-20 per cent aqueous solution, although it may be used in crystalline form. The reaction takes place readily at temperatures between about 100 C. and about 250 C. and its completion is usually indicated by the reaction mixture assuming the dark green color which is characteristic of certain chromic compounds. Upon completion of the reaction, the mixture is washed with hot water to remove any unreacted chromium trioxide, whereby the reaction product is obtained as a high-boiling dark green viscous liquid which is substantially insoluble in water but is readily soluble in a variety of organic solvents, e. g., hexane, benzene,

carbon tetrachloride, petroleum ether, etc.

The exact identity of the chromium-containing reaction products thus obtained and the nature of the reaction by which they are formed are not accurately known, and accordingly the reaction products are herein disclosed and claimed as such, rather than as chemical compounds whose identity can only be speculative.

While the above-described reaction products may be employed per se in inhibiting or preventing the corrosion or rusting of metals, by reason of their high viscosity they are more readily "applied to metal surfaces in the form of a solution or dispersion in a liquid vehicle. For example, they may be dissolved in a relatively light organic solvent, such as" hexane, benzene, petroleum ether,

carbon tetrachloride, or a light naphtha, to form slushing oil compositions of a viscosity suitable for application to metal surfaces by dipping, spraying, or brushing "procedures; Such light solvent will evaporate leaving a thin protective coating of the corrosion inhibiting reaction product on the metal surface. When it is desired to use the metal article thus protected, the'corrosion preventive coating may readily be removed by' washing with a suitable solvent. Gasoline is an excellent solvent for this purpose since it is cheap and universally available. The light petroleum distillate known as Stoddard solvent has been found particularly suitable for use as the solvent in preparing liquid protective coating compositions comprising the new corrosion preventives, and may also be used in the subsequent removal of th protective coating.

The amount of solvent employed will depend upon the nature of the solvent itself as well as upon the thickness of the coating desired on the metal. Ordinarily, however, suitable composie tions will contain up to about 75 per cent, preferably between about- 25 and about '75 per cent, by weight of the solvent. When it is desired to apply a thick corrosion preventive coating, the

amount of solvent is kept near the minimum, whereas if a thin coating is preferred, the amount of solvent may be considerably increased. For most applications, a composition comprising equal parts of solvent and the corrosion preventive material will be found very satisfactory.

While the corrosion preventive reaction products of the present invention eflectively inhibit the corrosion or rusting of metals for extended periods of time, I have found that the period of protection may be further extended through the use of a water-insoluble soap in conjunction with such products. Thus, for example, the period of protection against corrosion provided by the reaction product of chromium trioxide and 2-oleyl- 4-methy1-4-hydroxymethyl-2-oxazoline is concomplete.

be substituted other metals which form waterinsoluble soaps, e. g., calcium, barium, strontium. aluminum, etc. Similarly, the soya bean. oll fatty acid may be substituted by the fatty acids of other oils, such as cotton-seed, peanut, tung, linseed, perilla, corn, and oiticica oils. In place of natural oil fatty acids which are composed of mixtures of individual acids, a single fatty acid, such as palmitic, oleic, stearlc, or linoleic acid may be used. The amount of such soaps may vary from about 25 to about '75 per cent of the combined weight of soap and corrosion preventive reaction product.

In testing and demonstrating the efiiciency of the new reaction products as corrosion preventives, a modification of the testing procedure described in paragraph F-3a(7) of the "Bureau of Ships Ad Interim Specifications, 52C18 (INT), dated March 1, 1944, is conveniently employed. According to this test, two polished panels of SAE 1020 steel, 6 inches long by 3 inches wide and ,4; inch thick, are immersed in a solution consisting of equal parts of the corrosion preventive being tested and a petroleum distillate solvent having the following characteristics:

Gravity, API 48.5 Flash point (TCC), F 104 Initial boiling point, "F 312 'End boiling point, "F 394 Thesteel panels are removed from this solution and allowed to dry for 48 hours, during which time the solvent evaporates leaving a residual coating of the corrosion preventive material on the panels. The panels 50 prepared, together with any desired blank panels, are then subjected to an accelerated corrosion test in a National Carbon Weathering unit, model X-l-A. In this apparatus, the specimens to be tested are hung on a circular racl-r which rotates once every two hours. During this period the panels are sprayed for minutes with fresh water, and for the remaining hour and minutes they are subjected to intense ultraviolet radiation produced by a carbon arc lamp. The panels are examined daily for the appearance of rust, the time required for the appearance of the first rust spot being taken as a measure of the efficiency of the corrosion preventive under test.

The following examples will illustrate several ways in which the principle of the invention has been applied, but are not to be construed as limiting the same.

Example, I

Approximately 100 parts b weight of 2-oleyl- 4-methyl 4 hydroxymethyl 2 oxazoline was mixed with approximately 10 parts by weight of chromium trioxide at room temperature. The 2- oleyl 4 methyl-4-hydroxymethyl 2-oxazoline employed wasa commercial product boiling in the range of 174-305 C. and havin an average molecular weight of 350, and the chromium trioxide was employed in the form of a 20 per cent aqueous solution. The mixture was slowly heated with stirring to a temperature of about 95-115 C., and was held at this temperature until foaming subsided and dehydration was practically The temperature was then raised to 215-230 C. over a period of 30-60 minutes. and was held in this range for about 30 minutes. During this final heating period the reaction was completed and the mixture became'considerably more viscous. It was then cooled and washed with boiling water to remove any water-soluble materials, and the water-insoluble product was heated to drive off any residual water. The reaction product thus obtained was a dark green liquid having the consistency of thick honey. It was highly soluble in a variety of organic solvents, and had an average molecular weight of 1160. Its composition by chemical analysis was as follows:

Per cent by weight Carbon 66.0 Hydrogen 10.4 Nitrogen 3.2 Chromium 56 Oxygen (by difference) 14.8

This reaction product was tested for effectiveness as a corrosion preventive by the accelerated weathering test previously described. Of the two panels coated with the reaction product, one showed rusting only after 31 days of continuous treatment in the weatherometer, while the other panel did not corrode until it had been in the weatherometer for 59 days. In contrast, both an uncoated panel and a panel coated with 2-oleyl- 4-methyl-4-hydroxymethyl-2-oxazoline considerable rusting in one day. For purposes of checking, two more sets, each consisting of two panels coated with the reaction product, were tested. One of the panels corroded on the thirtyfirst day, but the remaining three did not corrode until after 51 days in the weatherometer,

Example II was a so tested. The panels which had been treated with the composition containing the reaction product andthe zinc'soap of soya bean oil were still bright and shiny and had no rust spots after sixty days of continuous treatment in the weatherom'eter, whereas the panel coated only with the zinc soap of soya bean oil corroded after nine days of treatment.

Example III 2-heptadecyl-4-methyl 4. hydroxymethyl-2- oxazoline was prepared by dissolving equimolecular quantities of stearic acid and 2-amino-2- methyl-propanediol-1.3 in toluene, and heatinr! to a temperature at which water was distilled ofi in the form of an azeotrope with the toluene. Upon completion of the reaction, as evidenced by the removal of two molecular equivalents of water in this manner, the reaction mixture was transferred to a distillation flask and was distilled under vacuum, whereby the oxazoline product was obtained as a waxy white solid having a, melting point of about 50-58 C. It had the following analysis:

' Per cent by weight Carbon 74.2 Hydrogen 11.8 Nitrogen 4.1 Oxygen (by diiference) 9.9

A sample of this product was heated to a temperature of about C., and 10 per cent by weight of chromium trioxide was added in the form of a 20 per cent aqueou solution. The mixture was then showed slowly heated with stirring to a temperature of about l-.-l25 C., and was maintained at this temperature until dehydration was practically complete. The temperatur was then raised to, about 205-220 C. for about 15 minutes, after which the reaction mixture was cooled and was washed with boiling water to remove any excess chromium trioxide. The water-insoluble reaction product was dried by heating, and was obtained as a very viscous dark green liquid. A sampe of this product was dissolved in an equal weight of light petroleum distillate to form a slushing oil composition which was then applied to polished SAE 1020 sfeel'test panels. When these panels were subjected to the corrosion test as hereinbefore described, they showed signs oi corrosion only after 68 days exposure in the weatherometer.

' Example IV 2oleyl-2-oxazoline was prepared from oleic acid and beta-amino-ethanoi as described in Example III. The product was obtained as a viscous liquid distilling at 180-220 C. under 1.5 mm. pressure, from which there was isolated by cooling a white crystalline solid having a melting point of about 65-70 C. A sample of the liquid product was heated with per cent by weight of chromium trioxide as described in Example III to obtain a dark green viscous liquid reaction product. Steel panels which had been coated with this product in the form of a 50 per cent solution in Stoddard solvent, and then corrosion tested as herein described, showed evidence of corrosion after 19 days exposure in the weatherometer.

Example V trioxide, as described in Example III, and the resulting reaction product was dissolved in an equal weight of Stoddard solvent. Steel panels which had been coated with this solution by dipping showed signs of rusting only after days exposure in the weatherometer. Example VI Approximately 275 parts by weight of a naphthenic acid having a. neutralization equivalent of 275 were reacted with 119 parts by weight or 2-amlno-2-ethyl-propanediol-1,3, as described in Example III, to obtain a 4-ethy1-4-hydroxymethyl-z-oxazoline compound having a n'aphthenic acid residue substituted in the 2-position. This product was a dark viscous liquid which distilled in the range 2Q0250 C. under 1.2 mm. ressure. 6

Upon reacting this produchwi-th chromium trioxide, as described in Example III, there was obta'ncd a viscous dark green l'quid which, when tested as a corrosion preventive as herein described. gave an average or 25 days protection against rustin in the weatherometer. An analogous product, prepared by reacting chromium 'trioxide with the oxazoline compound obtained from the same naphthen'c acid and 2-amino-2- methyl-propanediol-l,3, gave an average of 35 days protection in the weatherometer.

Example VII A mixture of approximately 220 parts by weight of petroleum, and 105 parts by weight 01' 2-amino- 2-methyl-propanediol-1,3 was heated until two molecular equivalents of water had been distilled ofl to obtain a 4-methyl-4-hydroxymethyl-2- oxazoline compound having the oxidized petroleum acid residue substituted in the2-position. This product was a thick dark liquid distilling in the range 100-l90 C. under 1.2 mm. pressure. Upon reacting this product with 10 per cent by we'ght of chromium trioxide there was obtained a dark green viscous liquid whichgave an average of 27 days protection against rusting when tested as a corrosion preventive in the weath erometer. An analogous product, prepared by reacting chromium trioxide with the oxazoline compound obtained from the same mixture of ac ds derived from the oxidation of petroleum and 2-amino-2-ethyl-propanediol-1,3, gave an average of 29 days protection against corrosion in the weatherometer.

Example VIII Example IX 2 pentadecyl 4 ethyl 4 hydroxymethyl- 2-oxazoline was obtained as a viscous liquid distilling at 192-215 C. under 1.2 mm. pressure by distilling two molecular equivalents of water from an equimolecular mixture of palmitic acid and 2-amino-2-ethyl-propanediol-1,3. Upon chilling, a white solid having a melting point 01' 36-38 C. crystallized from the liquid product. A sample of the liquid material was heated with 10 per cent by weight of chromium trioxide in aqueous solution to obtain a dark green liquid reaction product which was eifectiveas a corrosion preventive for a period of 18 days when tested as described above.

For purposes of providing comparative test data. the slushing oil compositions prepared in the above examples all comprised a reaction product of the present class dissolved in a standard light petroleum distillate solvent. However, a variety or other solvents or liquid dispersing media may be employed to prepare a wide variety of tions. Thus, the reaction products herein described may be dissolved or dispersed in heavier oils and the like or even petrolatum to provide 0 thick liquid or grease-like compositions. Similarly, various additives, particularly the watersoluble soaps herein disclosed, may be incorporated in such compositions for the further modification of their properties.

Other modes of applying the principle or my invention may be employed instead of those explained. change being made as regards the ingredients or methods employed, provided the features set forth in any of the append-ed claims be attained.

This application is a continuation-in-part oi" my co-pending application, Serial Number 633,557, flied December 7, 1945.

I claim:

of a mixture of acids derived from the oxidation l. A chromium-containing product obtained by quantities of oleic acid and 2-- N YII e Y! wherein R represents the hydrocarbon residue of an acid selected from the group consisting of higher fatty acids, naphthenic acids, and acids derived from the liquid phase partial oxidation of petroleum products, Y and Y each represents a substituent selected from the group consisting of hydrogen and lower alkyl groups. and Y" represents a substituent selected from the class consisting of hydrogen, lower alkyl groups, and lower hydroxyallgyl groups, with chromium trioxide at a temperature between about 100 C. and about 250 C.

2. A chromium-containing product obtained by heating an oxazoline compound having the general formula RC CHY N Y" i wherein R represents the hydrocarbon residue of a naphthenic acid, Y and Y' each represents a substituent selected from the group consisting of hydrogen and lower alkyl groups, and Y" rep-- resents a substituent selected from the class consisting of hydrogen, lower alkyl groups, and lower hydroxyalkyl groups, with chromium trioxide at a temperature between about 100 C. and about 250 C.

4. A chromium-containing product obtained by heating an oxazoline compound having the formula i CH.OH

wherein R, represents the hydrocarbon residue of an acid selected from' the group consisting of higher fatty acids, naphthenic acids, and acids derived from the liquid phase partial oxidation of petroleum products, with chromium trioxide at a temperature between about 100 C. and about 5. A chromium-containing product obtained by heating 2-heptadecyl-4-methyl-4-hydroxymethyl-2-oxazoline with chromium trioxide at atemperature between about 100 C. and about 250 C.

6. A chromium-containing product obtained by heating 2-peptadecyl-4-methyl-4-hydroxymcthyl-2-oxazoline with chromium trioxide at a temperature between about C. and about 250 C.

7. A chromium-containing product obtained by heating an oxazoline compound having the formula wherein R represents the hydrocarbon residue of a naphthenic acid, with chromium trioxide at gsiemperature between about 100 C. and about 8. A composition of matter adapted to prevent corrosion of metal surfaces, said composition consisting of from about 25 to about 75 per cent by weight of the product defined by claim 1 and from about 75 to about 25 per cent by weight of a petroleum distillate solvent for said Product.

9. A composition of matter adapted to prevent corrosion of metal surfaces, said composition consisting of approximately equal parts by weight of the product defined by claim 1 and a petroleum distillate solvent for said product.

10. A composition of matter adapted to prevent corrosion of metal surfaces, said composition consisting of approximately equal parts by weight of the product defined by claim 5 and a petroleum distillate solvent for said product.

11. A composition of matter adapted to prevent corrosion of metal surfaces, said composition consisting of approximately equal parts by weight of the product defined by claim 6 and a petroleum distillate solvent for said product.

12. A composition of matter adapted to prevent corrosion of metal surfaces, said composition consisting of approximately equal parts by weight of the product defined by claim 7 and a petroleum distillate solvent for said product.

13. A composition of matter adapted to prevent corrosion of metal surfaces, said composition consisting of from about 25 to about '75 per cent by weight of a mixture consisting of (1) from about 25 to about '75 per cent by weight of a waterinsoluble soap and (2) from about 75 to about 25 per cent by weight of a chromium-containing product obtained by heating an oxazoline compound having the general formula wherein R represents the hydrocarbon residue of an acid selected from the group consisting of higher fatty acids, naphthenic acids, and acids derived from the liquid phase partial oxidation of petroleum products, Y and Y each represents a substituent selected from the group consisting of hydrogen and lower alkyl groups, and Y" represents a substituent selected from the class consisting of hydrogen, lower alkyl groups, and lower hydroxyalkyl groups, with chromium trioxide at a temperature between about 100 C. and about 250 C., and from about 75 to about 25 per cent by weight of a petroleum distillate solvent for said mixture of water-insoluble soap and oxazollne compound. a

14. A process for the preparation of a product adapted to prevent the corrosion of metal sur- 11 faces, said process comprising heating an oxazoline compound having the general formula RO \OH--Y wherein R. represents the hydrocarbon residue of an acid selected from the group consisting of higher fatty acids, naphthenic acids, and acids derived from the liquid phase partial oxidation of petroleum products, Y and Y each represents a substituent selected from the group consisting of hydrogen and lower alkyl groups, and Y" represents a substituent selected from the class con sisting of hydrogen, lower alkyl groups, and lower hydroxyalkyl groups, with chromium trioxide at a temperature between about 100 C. to about 200 C.

15. A process for the preparation of a product adapted to prevent the corrosion of metal 8111" faces, said process comprising heating an oxazoline compound having the general formula hydrogen and lower alkyl groups, and Y" represents a substituent selectedfrom the class consisting of hydrogen, lower alkyl groups, and lower hydroxyalkyl groups, with chromium trioxlde at a temperature between about C. and about 250 C..for a time sumcient to efiect the formation of a dark green viscous liquid reaction product having corrosion preventive properties.

PAUL R. MCCARTHY.

REFERENCES CITIED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,33%,071 Cook et a1 Nov. 9, 1943 1,364,134 Morgan Jan. 4, 1921