Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
  • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
  • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
  • C23G1/04—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors
  • C23G1/06—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors organic inhibitors
  • C23G1/061—Cleaning or pickling metallic material with solutions or molten salts with acid solutions using inhibitors organic inhibitors nitrogen-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/08—Anti-corrosive paints
  • C09D5/082—Anti-corrosive paints characterised by the anti-corrosive pigment
  • C09D5/086—Organic or non-macromolecular compounds
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23F—NON-MECHANICAL REMOVAL OF METALLIC MATERIAL FROM SURFACE; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL; MULTI-STEP PROCESSES FOR SURFACE TREATMENT OF METALLIC MATERIAL INVOLVING AT LEAST ONE PROCESS PROVIDED FOR IN CLASS C23 AND AT LEAST ONE PROCESS COVERED BY SUBCLASS C21D OR C22F OR CLASS C25
  • C23F11/00—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent
  • C23F11/04—Inhibiting corrosion of metallic material by applying inhibitors to the surface in danger of corrosion or adding them to the corrosive agent in markedly acid liquids

Definitions

• ABSTRACT A method of inhibiting the corrosion of steel by acidic compounds. which comprises adding to the acidic compound an organic nitrogen compound containing at least one unsaturated carbon-nitrogen bond (other than a cyclic vicinal dinitrile) or by pre-treatment of the steel with the organic nitrogen compound or by a combination of both methods.
• This invention relates to the inhibition of the corrosion of steel by acids, and more particularly to the use of certain organic nitrogen compounds as corrosion inhibitors.
• organic compounds containing at least one unsaturated carbon-nitrogen bond which may be used as corrosion inhibitors according to the present invention
• organic compounds containing at least one unsaturated carbon-nitrogen bond which may be used as corrosion inhibitors according to the present invention
• these classes of compounds containing one or more nitrile, isonitrile, oxime, hydrazone, amidine, amidoxime, semicarbazone, hydrazone or imine group the latter class including groups which form part of a heterocyclic ring system as in, for example, oxazoles, oxadiazoles, furazans, furoxans, iminazoles, pyrazoles, pyrazolones, pyrazolines and triazoles.
• Suitable compounds include acrylonitrile and substituted acrylonitriles, for example, crotononitrile, cinnamonitrile, p-methoxycinnamonitrile and l-cyano-4- phenylbuta-l ,3-diene; benzonitriles and naphthonitriles carrying non-ionised electron-donating groups, for example, hydroxy, alkoxy, alkyl, halogen, trihalogenomethyl, thiol and thioether groups, specific examples of which include p-chloro-benzonitrile, pmethoxybenzonitrile, p-dodecylbenzonitrile, ptrichloromethylbenzonitrile, m-tolunitrile and l-cyano- 4-methoxy-naphthalene; other substituted benzonitriles, including p-nitro-benzonitrile, pdimethylaminobenzonitrile, and p-aminobenzontrile; N
• a preferred class of compounds particularly effective in protecting mild steels as well as stainless steels against acid attack, consists of conjugated unsaturated nitriles.
• conjugated unsaturated nitriles there may be mentioned lcyano-4-pyrimidin-2-ylbutal .3-diene, l-cyanobut-l-ene-3-yne, l-cyanohexa-l,5-diene-3-yne and 6-cyanohexa-l,3,5-triene-l-yl dimethyl phenyl ammonium salts, for example, the chloride, bromide, iodide, methosulphate or ethosulphate, but preferred compounds in this class are cinnamonitrile, p-methoxycinnamonitrile, crotononitrile and l-cyano-4- phenylbuta-l ,3-diene.
• a second preferred class of compounds also particularly effective in inhibiting acid attack on mild steel, consists of conjugated unsaturated oximes, of which preferred compounds are cinnamaldoxime, benzalacetoxime and dibenzalacetoxime.
• organic acids against the corrosive attack of which the above compounds are effective there may be mentioned monocarboxylic acids such as formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, stearic acid, monochloro-, dichloroand trichloroacetic acids and the corresponding bromoacetic acids, lactic acid, dicarboxylic acids such as oxalic acid, succinic acid, gluratic acid, adipic acid, pimelic acid, ter'ephthalic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic and dodecanedioic acid, tartaric acid and tricarboxylic acids such as citric acid and trimesic acid.
• monocarboxylic acids such as formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, stearic acid, monochloro-, dichloro
• the method of the present invention is also effective against attack by organic sulphonic acids.
• aqueous sulphurous acid As exaples of inorganic acids, the corrosive effects on steel of which are minimised according to the invention, there may be mentioned aqueous sulphurous acid, sulphuric acid, aqueous solutions of hydrogen halides, e.g., hydrochloric acid, sulphamic acid and nitric acid.
• hydrogen halides e.g., hydrochloric acid, sulphamic acid and nitric acid.
• the method is also effective against the corrosion of steels by derivatives of acids which may undergo chemical reaction with consequent liberation of the free acids, for example, anhydrides, esters and amides in the case of carboxlic acids and is applicable both to the anhydrous acids and aqueous solutions thereof.
• the corrosion-inhibiting compounds used according to the present invention are effective at temperatures from ambient temperature or below up to 240C or even higher.
• an effective amount we mean an amount of the organic nitrogen compound which is effective in inhibiting corrosion under the prevailing conditions.
• Pre-treatment of steel with the inhibitor compound may be carried out using the compound neat, as vapour or as a solution in a suitable solvent.
• a suitable solvent for example water, alcohols, acids, bases such as pyridine and quinoline, and nitriles and at temperatures up to 300C.
• the inhibitor compounds may also be incorporated in paints, primers, and wax or polish compositions intended for application to steel and in impregnated interlining and packing materials such as paper intended for wrapping and protecting steel.
• the inhibitor compounds may also be used as corrosion inhibitors in acid pickling baths which are employed in removing oxide scale from ferrous metals. and these uses form further features of the invention.
• a wide variety of steels maybe protected against corrosion using the methods described above, for example, stainless steels of American Iron and Steel Institute EXAMPLE l-27
• the mixture was heated in a Wood's Metal bath at 240 i 10C for hours and the sample was removed, washed, dried, weighed and its 20 appearance noted.
• Some samples were given a preliminary treatment by heating for 1 hour with a 2 percent w/v solution of inhibitor in an appropriate solvent at the boil and then allowed to cool during 24 hours before testing.
• EXAMPLES 48-55 A rectangular mild steel strip. 3.5 g. in weight, approximately 2 X X 1/32 inch is placed in an 8 X 1 inch test-tube fitted with air and water-cooled condensers in series, together with l6 w/w hydrochloric acid (50 ml) to which the inhibitor is added and is then heated at 80 1 1C for the times indicated in the following table. The metal samples were weighed before and after exposure to the acid.
• a method of inhibiting the corrosion of steel by acidic compounds which comprises adding to the acidic compound an effective amount of a compound selected from the group consisting of nitriles, aldoximcs and ketoximes.
• the nitrile is further selected from the group consisting of nitriles in which the nitrile group is attached to an unsaturated aliphatic carbon chain to form a conjugated system including the nitrile group and at least two double bonds in the chain, and nitriles in which the nitrile group is attached to an unsaturated aliphatic carbon chain which is itself attached to a benzene nucleus to form a conjugated system including the nitrile group.
• the aldoximes and ketoximes are further selected from the group consisting of orthobenzene quinone dioxime, parabenzoquinone dioxime, aldoximes and ketoximes in which the oxime group is directly attached to a benzene nucleus and aldoximes and ketoximes in which the oxime group is attached to a benzene nucleus through an unsaturated aliphatic carbon chain to form a conjugated system including the benzene nucleus, the oxime group and at least one double bond in the unsaturated aliphatic carbon chain.
• a method as claimed in claim 1 wherein the acidic compound is an organic sulphonic acid or an inorganic acid.
• the corrosion inhibiting compound is a conjugated unsaturated nitrile selected from the group consisting of cinnamonitrile, p-methoxy-cinnamonitrile, phenylmaleonitrile and l-cyano-4-phenylbuta-l,3-diene.
• the corrosion inhibiting compound is a conjugated unsaturated oxime selected from the group consistingof cinnamaldoxime, benzalacetoxime, acetophenoneoxime and dibenzalacetoxime.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Life Sciences & Earth Sciences (AREA)
• Wood Science & Technology (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Preventing Corrosion Or Incrustation Of Metals (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

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Publications (1)

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Cited By (21)

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Citations (14)

Family Cites Families (2)

• 1971
  • 1971-03-25 GB GB780771*[A patent/GB1365291A/en not_active Expired
  • 1971-09-13 NO NO3399/71A patent/NO131896C/no unknown
  • 1971-09-13 CA CA122,707A patent/CA963647A/en not_active Expired
  • 1971-09-17 BE BE772782A patent/BE772782A/fr unknown
  • 1971-09-17 IL IL7137748A patent/IL37748A/xx unknown
  • 1971-09-22 IT IT28952/71A patent/IT939022B/it active
  • 1971-09-23 AU AU33836/71A patent/AU459612B2/en not_active Expired
  • 1971-09-24 DE DE19712147847 patent/DE2147847A1/de active Pending
  • 1971-09-24 NL NL7113205A patent/NL7113205A/xx not_active Application Discontinuation
  • 1971-09-24 SE SE7112125A patent/SE383002B/xx unknown
  • 1971-09-24 FR FR7134544A patent/FR2107997B1/fr not_active Expired
  • 1971-09-25 ES ES395432A patent/ES395432A1/es not_active Expired
• 1974
  • 1974-01-24 US US436351A patent/US3876371A/en not_active Expired - Lifetime

Patent Citations (14)

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