US3551348A - Allenics for inhibiting corrosion - Google Patents

Description

United States Patent 3,551,348 ALLENICS FOR INHIBITING CORROSION Arthur H. Du Rose, Richmond Heights, Ohio, assignor to Kewanee Oil Company, Bryn Mawr, Pa., a corporation of Delaware N0 Drawing. Filed Sept. 21, 1967, Ser. No. 669,400 Int. Cl. C23f 11/10 US. Cl. 252-388 10 Claims ABSTRACT OF THE DISCLOSURE This invention covers the use of allenic compounds as corrosion inhibitors in acidic aqueous solutions to protect ferrous, zinc and aluminum containing materials. The concentration can range from about 0.005 to about 4 grams per liter.

This invention relates to a method for inhibiting corrosion of ferrous, zinc and aluminum metal and alloys, More specifically it concerns a method for inhibiting corrosion of such metals in aqueous acid environments by use of certain allenic compounds. It also includes the enhancement of the inhibiting power of allenic compounds by use of wetting agents or low concentration of iodides.

Allenic compounds while frequently mentioned in the literature, are still somewhat of a rarity in commercial quantities or commercial use. However it is known that their reactions are similar to those of olefins, the two ethylenic linkages acting independently of each other and addition at double bonds is subject to the influences of other groups as are observed with other ethylenic compounds. The most simple allenic compound is allene, CH C=CH a gas at ordinary temperatures and therefore not practical as an inhibitor.

It is well known that metals such as steel, zinc and aluminum when in contact with water and especially acidic water are slowly to rapidly corroded. In some cases this is the desired effect but in most cases it is desirable to prevent or retard corrosion.

Therefore a wide variety of compounds that retard corrosion have been uses as inhibitors in water and acidic solutions. Such known inhibitors include; labile organic sulfur compounds such as thiourea, dipropargyl sulfide and mercapto compounds; nitrogen compounds such as polyamines, decylamine and piperidinium 3,5 dinitrobenzoate; phosphorous compounds such as alkyl phosphate esters and alkyl selenophosphates; aldehydes; and inorganic compounds such as nitrites and chromates are also used. It is also known that compounds containing the single double bond or triple bond may be good inhibitors. Acetylenic compounds such as propargyl alcohol and 2- methyl-3-butyn-2 01 are especially good inhibitors. It is well known in the art that anionic, cationic, nonionic, and amphoteric wetting agents will frequently enhance the effectiveness of an inhibitor. This is also true for small concentrations of halides, particularly iodide.

Inhibitors are used in metal cleaning formulations, in acid pickling, where it is desired to remove scale and rust with but little attack on the basis metal, in hydraulic fluids, in lubricating oil emulsions, in metal paints and also as vapor inhibitors in packaging.

The mechanism by which an inhibitor functions has been given much study. In general, it has been concluded that the inhibitor adsorbs, usually by chemisorption, on the surface of the metal. The adsorption may take place on anodic or cathodic sites or possibly, in some cases, form an almost complete adsorbed film over the surface atoms of the metal.

This has led to various types of electrochemical polarization measurements to determine the extent of probable corrosion inhibition and to determine whether the corrosion is under cathodic or anodic control. Another method to evaluate the degree of corrosion is to measure the volume of hydrogen evolved when the metal is exposed to an acidic solution for a given period of time.

The method which is usually employed and which is almost always used to correlate with the polarization studies is the simple weight loss method. In this method two coupons of metal of given area are exposed to the same acidic solutions, one solution containing a small concentration of inhibitor and the other no inhibitor. The tests are performed under the same condition of temperature, time and agitation. The efficiency of inhibition is then calculated as AwAw where Aw and Aw are the metal weight losses for the coupons in the uninhibited and inhibited solution respectively. This is the method we have chosen to show the effectiveness of allenic compounds as inhibitors.

In accordance with the present invention it has been found that the cumulative effect of adjacent double bonds as found in allenic compounds including cumulene makes such compounds considerably more effective than simple olefins.

The compounds found to be particularly suitable as inhibitors in acid solutions are defined by the formula:

R is hydrogen or an alkyl radical of 1-4 carbon atoms,

or two Rs can be aliphatic hydrocarbon divalent radicals joined to form a six-membered cycloaliphatic ring With the carbon of the formula,

R is hydrogen or an alkyl radical of 1-4 carbon atoms,

R is a divalent saturated aliphatic hydrocarbon radical of 26 carbon atoms,

Ar is phenylene, naphthylene, diphenylene or an alkylene derivative having 14 carbon atoms in the alkylene group, and

n is an integer having a value of 1 to 10.

The concentration of the allenics of the instant invention required to effect corrosion inhibition vary according to the conditions of use and the particular allenic used. However, concentrations as low as 0.005 gram per liter have been effective to substantially inhibit corrosion of iron, zinc and aluminum. The only upper limit on allenic concentration in the practice of the instant invention is the solubility limit of the particular allenic used or its vapor saturation point when used in a non-aqueous corrosion inhibition situation. In no case, however, is any additional corrosion inhibition realized by exceeding in an allenic concentration of 4 grams per liter.

Allenic compounds defined by the above generic for- 3 mula as being suitable in the practice of this invention include but are not limited to the following:

4 (33) CH2 C CHCH2N(C2H5)3Cl (34) cn cn c cncn iv (CH Br (35 CH =C=CHCH (OCH CH 0H 31) CIIFC C(C1I3)CII2(OCIIZCII)301I 01-13 37 CH =C=CHCH OCH CH OCH CH CH CH OH ou on (3a) tlL C ClI-U ou ofi 31) on clcn-c 11 NH CIIgCII:

crncrrg (40) ClIi-ClI C CII-CH nit-1101 The invention is best illustrated by the following examples. These examples are given by way of illustration and are not intended in any way to restrict the scope of the invention nor the manner in which it may be practiced.

EXAMPLE I Low carbon steel panels 0.75" X 6" are placed in a large test tube containing 8% v./v. of concentrated H 50 and a equal volume of concentrated hydrochloric acid and 0.2% of the inhibitor. Controls are also used in which the corrosive medium contains no inhibitor. The immersion time is 6 hours and the temperature is 32 C. Methyl butynol, a commonly used acetylenic inhibitor is used for comparison. The panels are weighed before and after the corrosion period and the inhibition efliciency calculated as previously described. Table 2 gives the results.

TABLE II ElIIClGlICY, Comprl. No. Inhibitor percent 1 Methyl butynol (2-methyl-3-butyn2ol). 94. 6 2,2-diethyl-penta-BAdiene-l-al.. 97. 2 l,2-butadiene-4-0l 96.2 t 1,2-butediene-4-ol ethylene oxide adduct..." 95. 0 l-allenyl-l-iormyl-cyclohex-3-ene U9. 1 i 2,Z-dimethyl-penta-3,4dien-l-al 94. 3 2 methyl-2,3-butadienyltrirnethylammo- 85. 3

nium chloride. l(pdimethylaminophenyl)-2,2dimetl1yl- 96. 5

penta-3,4-dienol HCl. l-allunyl-Lcarbinol-cyclohex-3-ene 94. 5 2,2-di1nethylpenta3,4-dienol 88. 7 2,2,5-trimethylhexa-lidienal 74. 7 2,3-butadienoic acid J2. 0

EXAMPLE II In this example the effect of concentration of the inhibitor is demonstrated. The conditions were similar to those of Example I except that 20% hydrochloric acid was used at room temperature and the corrosion period was 3.5 hours. The following table shows that very low concentrations may be used.

TABLE III Inhibitor.

percent Ellit-iency,

Panel v.1'v. Inhibitor percent 0. 05 Methyl butynol 90. l

0.10.... do i i i 98.5

EXAMPLE III Here is shown the effect of methyl pentynol and three allenic inhibitors on the corrosion of 0.032" thick A.C.S. reagent grade zinc in 5% v./v. sulfuric acid. The time was 2 hours, inhibitor concentration 0.2%, and performed at room temperature. The allene inhibitor numbers in Table IV as well as in those exanmles which 5 follow refer to the numbers in Table II. It will be noticed that the addition of the wetting agent in the case of panel 5C slightly increased the efliciency of inhibitor No.2.

TABLE IV Panel Inhibitor percent l-C Methyl pentynol 84. 2

2-C Allene #2 (2,2-diethylpenta-3,4-diene-l-al) 95. 8 3-0 Allene #5 (l-allenyl-l-fonnyl-eyclo-H-ene) 95. 4 4-0 Allene #11 (2,2,5-trirnethylhexa-3,4-dienal) 94. 5 5-0 Allene #2 (see above panel 2-C plus 0.1% v./v. Surt- 96 5 ynol (a surface active agent).

EXAMPLE IV TABLE V Efficiency, Panel Inhibitor percent 1-B Methylpentynol (3-rnethyl-1-pentyl-3-ol) 78. 2-13 Allene #2 (2,2-diethyl-penta-3,4-dien-1-al) 66. 8 3-13 Allene #11 (2,2,5-trimethylhexa-3,4-dienal) 57. 3

EXAMPLE V Aluminum (alloy 6061) is immersed in sodium hydroxide at room temperature for 65 minutes. Allene No. 5 'was used at 0.1%. The efficiency was only 12% indicating that the allenic compounds do not have much promise as inhibitors for aluminum in alkaline solutions.

EXAMPLE VI Two steel strips are immersed in separate solutions containing 4% by volume sulfuric acid plus 0.2% by volume hydrochloric acid. One of the solutions contains 0.1% by Weight of Allene No. 7. The inhibitor efliciency after 2 hours immersion is 98.2%.

EXAMPLE VII Steel strips were immersed in 3M H 50 at room temperature for 4 hours. The efficiency of the inhibitor without and with the addition of 7 10 M K1 is shown in Table VI.

TABLE VI Inhibitor and concentration: Percent efficiency NO. 11 at 0.05% 58.5 N0. 11 at 0.05%, plus KI 99.820 No. 5 at 0.01% 80.6 NO. 5 at 0.01%, plus KI 99.846

EXAMPLE VIII Here is compared the eifect of an allene with a compound containing a single double bond and also with a compound containing two nonadjacent double bonds. Steel panels were immersed in 20% hydrochloric acid for 22 hours at room temperature. The inhibitor concentration was 0.1% and the efficiencies are shown in Table VII.

TABLE VII Efficiency, Inhibitor percent Panel:

1-D Allene #5 98. 5 2-D Methyl butenol (3-methyl-1-butene-3-ol) 58. 7 3-D 2,5-dimethyl-l,5-hexadienc-3-ol 58. 4

EXAMPLE IX The following test was performed as an indicative example of vapor inhibition. Several layers of filter paper were layed on the bottom of three 1 liter tall form beakers. In all cases the filter paper was saturated with water. About 0.5 g. of Allene No. 2 was added to the wet filter paper in one beaker and 0.5 g. of Allene No. 3 (see Example I) to that in another beaker. No inhibitor was added to the third beaker. Clean steel panels were then placed upright in the three beakers and these placed in a laboratory where the atmosphere was acidic and humid for four weeks. Once a week the filter papers were rewetted with water or water plus inhibitor. At the end of four weeks the steel in the beaker containing no inhibitor had become tarnished with yellow rust while the panels in the beakers containing the inhibitors were relatively tarnish-free.

From the previous examples, it is obvious that the effectiveness of allenic compounds as inhibitors can be equal or greater than that of acetylenic compounds. In this respect they resemble the acetylenic compound more than they do simple olefins or conjugated diolefins. It also appears that those allenes with a terminal double bond are more effective as inhibitors for steel than those which do not have the terminal double bond. In general this is also true for olefins and acetylenic compounds.

Due to the volatility of some of the allenic alcohols and aldehydes at elevated temperatures, it is generally advisable that the inhibitor containing solution be held at a temperature of less than 130 F. This restriction of course is not necessary for the allenic amines which form nonvolatile salts.

Allenic compounds used in the practice of this invention can be prepared by various methods taught in the prior art, including British Pat. 971,751; Bailey & Pfeifer, J. Org. Chem., 20, 1337-41 (1955); Eglinton et al., J. Chem. So., 3197-3200 (1954). Typical procedures are given below for various typical compounds.

1-a1lyl-2,2-demethyl-3 ,4-pentadienal A solution containing 0.15 mole of allylmagnesium bromide in 250 ml. of ether is added dropwise with cooling to a solution of 16.5 g. (0.15 mole) of 2,2-dim-ethyl- 3,4-pentadienal in 30 ml. of ether. After the reaction is complete the mixture is shaken with dilute hydrochloric acid. The ether phase is separated, Washed with fresh water and dried over sodium sulfate. Upon evaporation of the ether and distillation of the residue, 8.0 g. of product is collected which boils at 801 C. at 10 mm. Hg. Infrared analysis shows strong adsorption at 5.1 microns, which is characteristic of the allenic group, and strong adsorptions for hydroxyl and allyl groups.

1- (p-dimethylaminophenyl -2,2-dimethyl-3,4- pentadienol An ethereal solution containing 0.1 mole of p-dimethylaminophenyl lithium is added over a 0.5 hour period, at ice bath temperature, to an ethereal solution of 11.0 g. (0.1 mole) of 2,2-dimethyl-3,4-pentadenol. After the reaction is complete the mixture is cautiously hydrolyzed with an excess of water. The ether phase is separated and extracted with dilute hydrochloric acid. The combined extracts are washed with fresh ether and then neutralized with dilute sodium hydroxide. The product is extracted several times with ether and the combined extracts are dried over sodium sulfate. The product is precipitated from ether solution as the hydrochloric salt with anhydrous hydrogen chloride. A white solid, 15.0 g., is collected. Infrared analysis shows strong allenic absorption at 5.1 microns, and strong absorptions for hydroxyl, amino and phenyl groups.

l-formyl-1-allenylcyclohexene-3 A mixture of 23.0 g. (0.41 mole) of propargyl alcohol, 45.3 g. (0.41 mole) of 1-formylcyclohexene-3, 0.1 g. of hydroquinone and 0.1 g. of p-toluene sulfonic acid in ml. of benzene is heated at reflux for 5 hours. The water of reaction is collected in a Dean-Stark trap. Fractionation of the mixture affords 22.0 g. of product boiling at 7 groups.

71 C. at 3 mm. Hg. Infrared analysis shows strong absorption for the allenyl, aldehyde and cyclohexene groups.

l-hydroxymethyll-allenylcyclohexene-3 To a solution of 10.3 g. (0.07 mole) of l-formyl-lallenylcyclohexene-3 and 7.0 ml. of 40% formaldehyde solution in 25 ml. of methanol is added 8.4 g. of 50% sodium hydroxide solution over 15 minutes at 35-50 C. The mixture is then heated at 60 C. for 3 hours and poured into 300 ml. of water. The mixture is extracted with three 50 ml. portions of benzene. The combined extracts are dried over sodium sulfate and distilled. By this procedure, 6.5 g. of product, boiling at 95-6 C. at 3 mm. Hg is collected. The infrared analysis shows strong absorptions for the allenic, hydroxyl and cyclohexenyl 3,6-dioxa-8,9-decadien-l-ol A mixture of 1.0 g. of powdered potassium hydroxide and 40 ml. of isopropanol is stirred at reflux until the solids are dissolved. The solution is cooled at 25 C. and 10.0 g. (0.143 mole) of 2,3-butadiene-1-ol is added. With agitation, 13.2 g. (0.3 mole) of ethylene oxide is passed into the solution over a 30 minute period. The reaction temperature is maintained at 25-35 C. by intermittent cooling. After the addition is complete the mixture is stirred at 40-50 C. for 1 hour and then at 30 C. for an additional 2 hours. The catalyst is neutralized with hydrochloric acid and the mixture is filtered through a bed of Filter Cel. The isopropanol and nnreacted 2,3- butadiene-l-ol are distilled from the mixture to a maxi mum pot temperature of 80 C. at 10 mm. Hg. A dark orange, water soluble oil, 19.5 g., is obtained. Infrared analysis indicates strong absorption for the allenic, ether, and hydroxyl groups.

I claim:

1. A corrosion inhibited aqueous acid solution containing an effective corrosion inhibiting amount of an allenic compound of the formula R, R and R are selected from the group consisting of hydrogen and methyl,

X is selected from the group consisting of -CHO;

R is selected from the group consisting of hydrogen or an alkyl radical of l-4 carbon atoms, or two such R s can be aliphatic hydrocarbon divalent radicals joined to form a six-membered cycloaliphatic ring with the carbon of the formula,

R is selected from the group consisting of hydrogen and an alkyl radical of 1-4 carbon atoms,

R is a divalent saturated aliphatic hydrocarbon radical of 26 carbon atoms,

Ar is selected from the group consisting of phenylene, naphthylene, diphenylene or an alkylene having 1-4 carbon atoms, and

n is an integer of from 1-10.

2. A corrosion inhibited aqueous acid solution as stated in claim 1 wherein said allenic compound is present in a concentration of between about 0.005 and 4 grams per liter of solution.

3. A corrosion inhibited aqueous acid solution containing an effective corrosion inhibiting amount of 2.2-dicthylpenta-3,4-diene-1-al.

4. A corrosion inhibited aqueous acid solution contain R u-c:C:( X

wherein R. R and R are selected from the group consisting of hydrogen and methyl, X is selected from the group consisting of --CHO;

-COOH; --CH OH; -C(R CHO;

R is selected from the group consisting of hydrogen or an alkyl radical of l-4 carbon atoms, or two such R s can be aliphatic hydrocarbon divalent radicals joined to form a six-membered cycloaliphatic ring with the carbon of the formula R is selected from the group consisting of hydrogen an an alkyl radical of l-4 carbon atoms,

R is a divalent saturated aliphatic hydrocarbon radical of 2-6 carbon atoms,

Ar is selected from the group consisting of phenylene, naphthylene, diphenylene or an alkylene having 1-4 carbon atoms, and

n is an integer from 1l0.

7. A method of inhibiting corrosion of ferrous, zinc or aluminum containing materials in acidic aqueous solutions which comprises dissolving in said aqueous solutions between about 0.005 and 4 grams per liter of 2,2-diethyl- 3,4-diene-l-al.

8. A method of inhibiting corrosion of ferrous, Zinc or aluminum containing materials in acidic aqueous solutions which comprises dissolving in said aqueous solutions between about 0.005 and 4 grams per liter of l-allenyl-lformyl-cyclohex-B-ene.

9. A method of inhibiting corrosion of ferrous, zinc or aluminum containing materials in acidic aqueous solutions which comprises dissolving in said aqueous solutions between about 0.005 and 4 grams per liter of 2,3-butadienoic acid.

10. A method of inhibiting corrosion or tarnishing of ferrous, zinc or aluminum containing materials in a corrosive atmosphere contacting said metal containing materials with a corrosion inhibiting amount of an allenic compound in a vapor phase, said allenic compound being of the formula wherein R, R and R are selected from the group consisting of hydrogen and methyl, X is selected from the group consisting of -CHO;

-COOH; CH OH; -C(R CHO;

C(R COOH;

-C(R CH OH;

C(lifiJllAl'NUfih; '(u* 11o.u,N; C(lt") CllC;ll N on on on 9 10 --C(R N(R Cl; C(R (OR ),,OH; C H N; naphthylene, diphenylene or an alkylene having 1-4 carbon atoms, and and C H N, n is an integer from 1-10. R is selected from the group consisting of hydrogen or an alkyl radical of 1-4 carbon atoms, or two such 5 References Clted R s can be aliphatic hydrocarbon divalent radicals UNITED STATES PATENTS jOined t0 fOrIn a. siX-Inembered CyClOaliphatiC ring Jacobs et a1.

with the carbon of the formula, R is selected from the group consisting of hydrogen RICHARD D. LOVERING, Primary Examiner an an alkyl radical of 1-4 carbon atoms, 10 R is a divalent saturated aliphatic hydrocarbon radical GLUCK Asslstant Exammer of 2-6 carbon atoms, s, L

Ar is selected from the group consisting of phenylene, 252 143 396