GB2182030A

GB2182030A - Corrosion inhibition

Info

Publication number: GB2182030A
Application number: GB08625208A
Authority: GB
Inventors: Robert Montgomery O'neil; Emyr Phillips
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1985-10-23
Filing date: 1986-10-21
Publication date: 1987-05-07
Also published as: JPS6299484A; IT8622087A0; GB8526160D0; FR2588883A1; GB8625208D0; DE3635636A1

Abstract

A method of inhibiting the corrosion of paper or of a metal containing copper, comprising contacting the surface of the copper, or metal containing copper, with a corrosion-inhibiting amount of a triazole compound having the formula I: <IMAGE> wherein R1 is H or SH; and R2 is C2-C20 straight- or branched-chain alkyl, C5-C12 cycloalkyl, C7-C13 aralkyl, optionally substituted C6 or C10 aryl, pyridyl or a residue of formula II: <IMAGE> or, when R1 is H, (a) R2 may be a C6 or C10 arylene residue having the formula X-arylene- in which X is a residue of formula III: <IMAGE> or (b) R2 may be a residue X in which X has its previous significance, or (c) R2 may be a C1-C8 alkylene residue optionally substituted by a heteroatom and having the formula X-alkylene in which X has its previous significance.

Description

SPECIFICATION Corrosion inhibition The present invention relates to a method of inhibiting the corrosion of copper; and to compositions in contact with copper, and containing specified triazole corrosion inhibitors for copper.

It is well established that surfaces of copper are susceptible to corrosion when such surfaces come into contact with aqueous or non-aqueous media. Furthermore, the products of such copper corrosion may catalyse the decomposition of any organic media in contact with the corroded copper surface and may also induce corrosion of other metals, eg iron or aluminium, which may be present.

Many compounds of widely different structures have been proposed as copper corrosion inhibitors for use in media such as aqueous systems of functional fluids.

Amongst many others, one type of compound which has been found to be effective is that derived from 1,2,4-triazole. For example, in EP 25863, 3-amino-5-alkyl-1,2,4-triazoles are described and are said to be useful as corrosion inhibitors for non-ferrous metals in aqueous systems.

In earlier publications, totally different 1,2,4-triazole structures viz.. 3,5-di-substituted 1,2,4triazoles have been described as metal corrosion inhibitors in a wide range of systems. Thus in JP 51-10186 3,5-di-aryl-1,2,4-triazole corrosion inhibitors are disclosed; in JP 51-10187, 3,5di-alkyl (or benzyl)-1,2,4-triazole inhibitors are shown; in JP Kokai 48-62634, 3,5-di-hydrocarbyl (or heterncyclyl)-1,2,4-triazole corrosion inhibitors are described.

In corrosion Science 1980, Vol. 20, 1195 to 1200, 3-mercapto-5-aryl-1,2,4-triazoles are described as useful corrosion inhibitors not for copper, rather for mild steel.

Against this varied background art, suggesting many detergent metal corrosion-inhibiting 1,2,4triazole structures for different metals, we have now found, surprisingly, certain specific 1,2,4triazole derivatives which provide outstanding copper corrosion-inhibition in various media eg functional fluids and aqueous systems.

Accordingly, the present invention provides a method of inhibiting the corrosion of copper or of a metal containing copper, comprising contacting the surface of the copper, or metal containing copper, with a corrosion-inhibiting amount of a compound having the formula I:

wherein R1 is H or SH; and R2 is C2-C20 straight- or branched chain alkyl, C5-C,2 cycloalkyl, C7-C13 aralkyl, optionally substituted C6 or C10 aryl, pyridyl or a residue of formula ll:

or, when R1 is H, (a) R2 may be a C6 or C10 arylene residue having the formula X-arylene- in which X is a residue of formula Ill:

or (b) R2 may be a residue X wherein X has its previous significance, or (c) R2 may be a C1-C8 alkylene residue, optionally interrupted by a heteroatom and having the formula X-alkylene in which X has its previous significance.

When R2 is a C2-C20 alkyl group, it may be of straight- or branched chain eg ethyl, n-propyl, iso-propyl, n-butyl, sec-butyl, n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl or n-eicosyl.

C5-Cl2-Cycloalkyl groups R2 may be cyclopentyl, cyclohexyl, cyclooctyl, cyclodecyi, adamantyl or cyclododecyl.

C7-C13-Aralkyl groups R2 may be benzyl, 2-phenylethyl, benzhydryl or naphthylmethyl.

C6- or C10 Aryl groups R2 are phenyl or naphthyl. Optional substituents in these aryl groups are eg nitro and hydroxyl groups.

C1-C8 alkylene groups R2 include methylene, ethylene, 1,3-propylene, 1,4-butylene, 1,5-pentylene, 1,6-hexylene, 1 ,7-heptylene and 1,8-octylene, each optionally interrupted by a heteroatom eg an oxygen-, nitrogen- or sulfur atom.

C6- or C10 Arylene groups which are a component of the group X-arylene- are eg 1,2-, 1,3- or 1,4-phenylene and 1,4-naphthalene.

Preferred compounds of formula I are those having the formula IA:

in which R2, C2-C20 alkyl, phenyl, benzyl or X-alkylene (Cl-C8)-in which X is a residue of formula III. In the compounds of formula IA, R2, is preferably C4-C10 alkyl, phenyl, benzyl or X-alkylene (C,-C2) in which X is a residue of formula Ill.

Other preferred compounds of formula IB:

in which R2" is C2-C20 alkyl, especially C4-C1O alkyl.

Specific examples of compounds of formula I for use in the compositions of the inventions include: 3-Ethyl- 2,4-triazole, 3-n-Propyl- 1 ,2,4-triazole, 3-Iso-Propyl- 1 ,2,4-triazole, 3-n-Butyl- 1 2,4-triazole, 3-Sec. butyl -1,2,4-triazole, 3-n-Pentyl- 1 2,4-triazole, 3-n-Hexyl-1 2,4-triazole, 3-n-Heptyl- 1 ,2,4-triazole, 3-n-Octyl- 1 2,4-triazole, 3-(2-Ethylhexyl)- 1 ,2,4-triazole, 3-n-Nonyl-1 2,4-triazole, 3-n-Decyl- 1 ,2,4-triazole, 3-n-Dodecyl -1 ,2,4-triazole, 3-n-Tetradecyl- 1 ,2,4-triazole, 3-n-Hexadecyl-1 2,4-triazole, 3-n-Octadecyl- 1 ,2,4-triazole, 3-n-Eicosyl- 1 ,2,4-triazole, 3-Cyclopentyl-1 2,4-triazole, 3-Cyclohexyl-1 ,2,4-triazole, 3-Cyclododecyl-1 ,2,4-triazole, 3-Benzyl-1 ,2,4-triazole, 3-Phenyl- 1 2,4-triazole, 3-(4-Nitrophenyl)-1 2,4-triazole 3-Naphthyl-1 ,2,4-triazole, 3-(2-Pyridyl)- 1 ,2,4-triazole 3-(3-Pyridyl)- 1 ,2,4-triazole 3-(4-Pyridyl)- 1 2,4-triazole 3-(4H- 1 ,2,4-Triazolyl)- 1 ,2,4-triazole, 3 ,3'-( 1 ,2-Phenylene)-bis-( 1 2,4-triazole), 3,3'-(1 ,3-Phenylene)-bis-( 1,2,4-triazole), 3,3'-Bis-(1 2,4-triazole) 3,3'-Methylene-bis(1,2,4-triazole), 3 ,3'-Ethylene-bis( 1 ,2,4-triazole), 3,3'- [ 1 ,3-propylene ] -bis( 1 ,2,4-triazole) 3 ,3'- [ 1 ,4-butylene ] -bis( 1 2,4-triazole) 3,3'-1 ,8-Octylene-bis(1 ,2,4-triazole), 3-Ethyl-5-mercapto- 1,2,4-triazole, 3-n-Propyl-5-mercapto- 1,2,4-triazole, 3-lsopropyl-5-mercapto- 1 ,2,4-triazole, 3-n-Butyl-5-mercapto- 1,2,4-triazole, 3-Mercapto-5-n-pentyl- 1,2,4-triazole, 3-n-Hexyl-5-mercapto- 1,2,4-triazole, 3-n-Heptyl-5-mercapto- 1 ,2,4-triazole, 3-n-Octyl-5-mercapto- 1,2,4-triazole, 3-(2-Ethylhexyl)-5-mercapto- 1,2,4-triazole, 3-n-Nonyl-5-mercapto- 1,2,4-triazole, 3-n-Decyl-5-mercapto- 1,2,4-triazole, 3-n-Dodecyl-5-mercapto- 1,2,4-triazole, 3-n-Tetradecyl-5-mercapto- 1,2,4-triazole, 3-n-Hexadecyl-5-mercapto- 1 ,2,4-triazole, 3-n-Octadecyl-5-mercapto- 1,2,4-triazole, 1 2,4-triazole, 3-n-Eicosyl-5-mercapto- 1,2,4-triazole, 3-Cyclopentyl-5-mercapto- 1 ,2,4-triazole, 3-Cyclohexyl-5-mercapto- 1 2,4-triazole, 3-Cyclododecyl-5-mercapto- 1,2,4-triazole, 3-Benzyl-5-mercapto- 1 ,2,4-triazole, 3-Phenyl-5-mercapto- 1,2,4-triazole, 3-Naphthyl-5-mercapto- 1,2,4-triazole.

Particularly preferred compounds of formula I are: 3-Phenyl-1 2,4-triazole, 3-n-Hexyl-1 2,4-triazole, 3-n-Hexyl-5-mercapto- 1,2,4-triazole, 3,3'-Methylene-bis(1 2,4-triazole), 3,3'-Ethylene-bis(l,2,4-triazole).

3-Benzyl-1 ,2,4-triazole 3-Cyclohexyl-5-mercapto- 1,2,4-triazole and 3-Cyclohexyl-1 ,2,4-triazole.

Many of the compounds of formula I are known but some specific compounds viz. those having the formula:

wherein n is 2, 3 or 4 are new and, as such, form a further aspect of the present invention.

The compounds of formula I whether known or new may be produced by methods which are well known per se.

For example, the compounds of formula I in which Rl is hydrogen may be prepared by (a) cyclisation of the corresponding acylamidrazones using the method described by Heinz, Hilgetag and Jahnchen in Chem.Ber. 1968, 101, 2033; (b) by deamination of the corresponding 3-amino1,2,4-triazoles using the process described by Bachman and Heisey in J.Amer.Chem.Soc. 1949, 71, 1985; or (c) by de-sulfurisation of the corresponding 3-mercapto-1,2,4-triazoles using the method of Hoggarth in J.Chem.Soc. 1949, 1160.

Compounds of formula I in which Rl is a mercapto group may be synthesized by (a) cyclising the corresponding acylthiosemicarbazides using the method of Dutta et al. J.lndian Chem.Soc.

1968, 45, 338; or (b) condensing the appropriate carboxylic acid ester with thiosemicarbazide using the method of Willems and Vandenberghe, Bull.Soc.Chim.Belges. 1966, 75, 358).

The compounds of formula IV may be produced by desulphurisation of the corresponding, known 3,3'-alkylene-bis-1 ,2,4-triazole-5-thiones (Willems and Vandenberghe, supra), using the method of Jones and Ainsworth in J. Amer. Chem. Soc. 1953, 75, 4915.

The compound of formula I may be contacted with the copper surface to be protected by any of a variety of techniques. For example, the copper surface may be wrapped in a film impregnated with the compound of formula I or the copper surface may be dipped into a solution eg an aqueous solution containing a compound of formula I. More usually however, the copper surface will be permanently in contact with a substrate which causes corrosion of the copper surface. In such cases, the copper surface can be effectively inhibited against corrosion by adding a corrosion-inhibiting amount of a compound of formula I to the substrate.

The present invention therefore also provides a composition comprising a substrate in contact with copper, or a metal containing copper and a copper corrosion-inhibiting amount, preferably 0.0001% to 5% by weight, based on total weight of the substrate, of a compound of formula I as hereinbefore defined.

Examples of substrates which may be treated according to the present invention include functional fluids such as lubricants eg those having a mineral oil, poly-alpha olefin or synthetic carboxylic acid ester base; hydraulic fluids eg those based on mineral oils, phosphate esters, aqueous polyglycol/polyglycol ether mixtures or glycol systems; oil-in-water or water-in-oil systems; metal-working fluids having, as their base, mineral oil or aqueous systems; water- or aqueous glycol- or ethylene- or propylene glycol/methanol based engine coolant systems; transformer- or switch oils; as well as aqueous systems eg industrial cooling water; aqueous airconditioning systems; steam-generating systems; sea-water evaporator systems; hydrostatic cookers; and aqueous closed circuit heating or refrigerant systems.

For use in oil-based functional fluids, those compounds of formula I are preferred in which R1 is H and R2 is an oleophilic group, especially a C2-C10 straight- or branched-chain alkyl group, a C6 or C10 aryl group, a C7-C,3 aralkyl group or a C6-C12 cycloalkyl group.

On the other hand, for use in aqueous, glycol or water/glycol functional fluids, those compounds of formula I are preferred in which R1 is H or SH and R2 is C4-C7 straight- or branchedchain alkyl, C6 or C10 aryl, C7-C13 aralkyl or a residue of formula X-(CH2)n- in which X has its previous significance and n is O or 1 to 8, but in which n is preferably 0 or 1 to 4.

Those compounds of formula I in which R1 is SH are preferably incorporated into a functional fluid as pre-formed alkali metal (preferably sodium) or organic amine salts, or they may be dissolved in an aqueous functional fluid by adding to the latter an appropriate amount of an alkali (preferably sodium hydroxide).

Those compounds of formula I in which R1 is H may be incorporated into a functional fluid as the neutral species and, indeed, this technique is very much preferred when such compounds are incorporated into oil-based functional fluids.

Alternatively, for use in non-oil based functional fluids, the compounds of formula I may be used in either alkaline or acidic solution. In alkaline solution, sodium hydroxide is the preferred base used and, in acidic solution, the use of a mineral acid such as hydrochloric, sulfuric or phosphoric acid is preferred.

When a functional fluid substrate is a synthetic lubricant, examples thereof include lubricants based on a diester of a dibasic acid and a monohydric alcohol, for instance dioctyl sebacate or dinonyladipate; on a triester of trimethylolpropane and a monobasic acid or mixture of such acids, for instance trimethylol propane tripelargonate, trimethylolpropane tricaprylate or mixtures thereof; on a tetraester of pentaerythritol and a monobasic acid or mixture of such acids, for instance pentaerythritol tetracaprylate; or on complex esters derived from monobasic acids, dibasic acids and polyhydric alcohols, for instance a complex ester derived from trimethylol propane, caprylic acid and sebacic acid; or of mixtures thereof.

Other synthetic lubricants are those known to the art-skilled and described eg in "Schmiermittel-Taschenbuch" (Huethig Verlag, Heidelberg 1974). Especially suitable, apart from the preferred mineral oils are eg phosphates, glycols, polyglycols, polyalkylene glycols and poly-alpha olefins.

In order to improve various applicational properties, a functional fluid composition of the invention may also contain other additives such as, for oil-based systems, one or more of antioxidants, metal deactivators, further corrosion or rust inhibitors, viscosity-index improvers, pour-point depressants, dispersants/surfactants or anti-wear additives; and for aqueous-based systems, one or more of antioxidants, other corrosion- and rust inhibitors, metal deactivators, extreme pressure- or anti-wear additives, complexing agents, precipitation inhibitors, biocides, buffering agents and anti-foams.

For oil-based systems, examples of other additives are: Examples of phenolic antioxidants 1. Alkylated Monophenols 2,6-Di-tert.-butylphenol 2-tert.-butyl-4,6-dimethylphenol 2,6-Di-tert.-butyl-4-ethylphenol 2,6-Di-tert.-butyl-4-n-butylphenol 2,6-Di-tert.-butyl-4-i-butylphenol 2,6-Di-cyclopentyl-4-methylphenol 2-(ss-Methylcyclohexyl)-4,6-dimethylphenol 2,6-Di-octadecyl-4-methylphenol 2,4,6-Tri-cyclohexylphenol 2,6-Di-tert.-butyl-4-methoxymethylphenol 2. Alkylated Hydroquinones 2,6-Di-tert.-butyl-4-methoxyphenol 2,5-Di-tert.-butyl-hydroquinone 2,5-Di-tert.-amyl-hydroquinone 2,6-diphenyl-4-octadecyloxyphenol 3.Hydroxylated Thiodiphenylethers 2,2'-Thio-bis-(6-tert.butyl-4-methylphenol) 2,2'-Thio-bis-(4-octylphenol) 4,4'-Thio-bis-(6-tert.butyl-3-methylphenol) 4,4'-Thio-bis-(6-tert. butyl-2-methylphenol) 4. Alkylidene-Bisphenols 2,2'-Methylene-bis-(6-tert.-butyl-4-methylphenol) 2, 2'-Methylene-bis-(6-tert.-butyl-4-ethylphenol) 2,2'-Methylene-bis-(4-methyl-6-(a-methylcycloheXyl)-phenol) 2,2'-Methylene-bis-(4-methyl-6-cyclohexylphenol) 2,2'-Methylene-bis-(6-nonyl-4-methylphenol) 2,2'-Methylene-bis-(4,6-di-tert.-butylphenol) 2,2'-Ethylidene-bis-(4, 6-di-tert.-butylphenol) 2,2'-Ethylidene-bis-(6-tert.-butyl-4-isobutylphenol) 2,2'-Methylene-bis-(6-(a-methylbenzyl-4-nonylphenol) 2,2'-Methylene-bis-(6-(a, -dimethylbenzyl)-4-nonylphenol) 4,4'-Methylene-bis-(6-tert.-butyl-2-methylphenol) 1,1 '-Bis-(5-tert.-butyl-4-hydroxy-2-methylphenol)-butane 2,6'-Di-(3-tert. butyl-5-methyl-2-hydroxybenzyl)-4-methylphenol 1,1 ,3-Tris-(5-tert.butyl-4-hydroxy-2-methylphenyl)-3-n-dodecylmercaptobutane Ethyleneglycol-bis- [ 3 ,3-bis-(3'-tert.-butyl-4'-hydroxyphenyl)-butyrate ] Di-(3-tert.-butyl-4-hydroxy-5-methylphenyl)-dicyclopentadiene Di-[3'-tert.-butyl-2'-hydroxy-5'-methyl-benzyl)-6-tert.-butyl-4-methyl-phenyl]-terephthalate 5.Benzyl Compounds 1,3 ,5-Tri-(3 ,5-di-tert.-butyl-4-hydroxybenzyl)-2,4,6-trimethylbenzene Di-(3 ,5-di-tert.-butyl-4-hydroxybenzyl)-sulfide Bis-(4-tert.-butyl-3-hydroxy-2,6-dimethylbenzyl)dithiolterephthalate 1 ,3,5-Tris-(3,5-di-tert.-butyl-4-hydroxybenzyl)-isocyanurate 1.3. 5-Tris-(4-tert.-butyl-3-hydroxy-2 ,6-dimethylbenzyl)-isocyanurate 3,5-Di-Tert.-butyl-4-hydroxybenzyl-phosphonic acid-dioctadecylester 3,5-Di-tert.-butyl-4-hydroxybenzyl-phosphonic acid-monoethylester Calcium-salt 6.Acylaminophenols 4-Hydroxy-lauric acid anilide 4-Hydroxy-stearic acid anilide 2,4-Bis-octylmercapto-6-(3 , 5-di-tert.-butyl-4-hydroxyanilino)-s-triazine N-(3 ,5-di-tert.-butyl-4-hydroxyphenyl)-carbamic acid octyl ester 7. Esters of fi-(3, 5-Di-tert. -buty!-4-hydroxypheno!)-propionic acid with mono- or polyhydric alcohols eg with Methanol Diethyleneglycol Octadecanol Triethyleneglycol 1,6-Hexandiol Pentaerythritol Neopentylglycol Tris-hydroxyethyl-isocyanurate Thiodiethyleneglycol Di-hydroxyethyl-oxalic acid diamide 8.Esters of fl-(5-tert.-butyl-4-hydroxy-3-methylphenyl)-propionic acid with mono- or polyhydric alcohols eg with Methanol Diethyleneglycol Octadecanol Triethyleneglycol 1,6-Hexandiol Pentaerythritol Neopentylglycol Tris-hydroxyethyl-isocyanurate Thiodiethyleneglycol Di-hydroxyethyl-oxalic acid diamide 9.Amides of fi-(3,5-Di-tert.-butyl-4-hydroxyphenyl)-propionic acid eg N,N'-Di-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyi)-hexamethylene-diamine N,N'-Di-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)-trimethylene-diamine N,N'-Di-(3,5-di-tert.-butyl-4-hydroxyphenylpropionyl)-hydrazine Examples of amine antioxidants:: N,N'-Di-isopropyl-p-phenylenediamine N,N'-Di-sec.-butyl-p-phenylenediamine N,N'-Bis( 1 ,4-dimethyl-pentyl)-p-phenylenediamine N,N'-Bis( 1 -ethyl-3-methyl-pentyl)-p-phenylenediamine N,N'-Bis( 1 -methyl-heptyl)-p-phenylenediamine N,N'-Bis( 1 -methyl-heptyl)-p-phenylenediamine N,N'-Dicycldhexyl-p-phenylenediamine N,N'-Diphenyl-p-phenylenediamine N,N'-Di-(naphthyl-2-)-p-phenylenediamine N-lsopropyl-N'-phenyl-p-phenylenediamine N-( 1 ,3-dimethyl-butyl)-N'-phenyl-p-phenylenediamine N-( 1 -Methyl-heptyl)-N'-phenyl-p-phenylenediamine N-Cyclohexyl-N'-phenyl-p-phenylenediamine 4-(p-Toluene-sulfonamido)-diphenylamine N,N'-dimethyl-N,N'-di-sec.-butyl-p-phenylenediamine Diphenylamine 4-lsopropoxy-diphenylamine N-Phenyl- 1 -naphthylamine N-Phenyl-2-naphthylamine octylated Diphenylamine octylated N-phenyl- (or) naphthylamine 4-n-Butylaminophenol 4-Butyrylamino-phenol 4-Nonanoylamino-phenol 4-lsodecanoylamino-phenol 4-Octadecanoylamino-phenol Di-(4-methoxy-phenyl)-amine 2,6-Di-tert.-butyl-4-dimethylamino-methyl-phenol 2,4'-diamino-diphenylmethane 4,4'-Diamino-diphenylmethane N,N,N',N'-Tetramethyl-4,4'-diamino-diphenylmethane 1,2-Di-(phenylamino)-ethane 1,2-Di- [ (2-methyl-phenyl)-amino ] -ethane 1,3-Di-(phenylamino)-propane (o-tolyl)-biguanide Di- [ 4-(1 ',3'-dimethyl-butyl)-phenyl ] amine Examples of further metal passivators are: for copper eg Benzotriazole, tolutriazole and derivatives thereof, tetrahydrobenzotriazole,2-mercaptobenzthiazole, 2,5-dimercaptothiadiazole, salicylidene-propylenediamine and salts of salicylaminoguanidine.

Examples of rust inhibitors are: (a) Organic acids, their esters, metal salt and anhydrides eg N-oleoyl-sarcosine, sorbitan-monooleate, lead-naphthenate, dodecenyl-succinic acid (and its partial esters and amides), 4-nonyl-phenoxy-acetic acid.

(b) nitrogen-containing compounds eg.

I. Primary, secondary or tertiary aliphatic or cycloaliphatic amines and amine-salts of organic and inorganic acids eg oil-soluble alkylammonium carboxylates II. Heterocyclic compounds eg substituted imidazolines and oxalines (c) Phosphorus-containing compounds eg Amine salts of phosphonic acid partial esters, zinc dialkyldithio phosphates (d) Sulfur-containing compounds eg Barium-dinonylnaphthalene-n-sulfonates, calcium petroleum sulfonates Examples of viscosity-index improvers are eg Polymethacrylates, vinylpyrrolidone/methacrylate-copolymers, polybutenes, olefin-copolymers styrene/acrylate-copolymers.

Examples of pour-point depressants are eg Polymethacrylates, or alkylated naphthalene derivatives Examples of dispersants/surfactants are eg Polybutenylsuccinic acid-amides, polybutenylphosphonic acid derivatives, basic magnesium-, calcium-, and bariumsulfonates and -phenolates.

Examples of anti-wear additives are eg Sulfur- and/or phosphorus- and/or halogen-containing compounds eg sulfurised vegetable oils, zinc dialkyldithiophosphates, tritolylphosphate, chlorinated paraffins, alkyl- and aryldisulfides.

In the treatment of substrates which are completely aqueous, such as cooling water systems, air-conditioning system, steam-generating systems, sea-water evaporator systems, hydrostatic cookers, and closed circuit heating or refrigerant systems, further corrosion inhibitors may be used such as, for example, water soluble zinc salts; phosphates; polyphosphates; phosphonic acids and their salts, for example, acetodiphosphonic acid, nitrilotris methylene phosphonic acid and methylamino dimethylene phosphonocarboxylic acids and their salts, for example, those described in German Offenlegungsschrift 2632774, hydroxyphosphonoacetic acid, 2-phosphonobutane-1,2,4-tricarboxylic acid and those disclosed in GB 1572406; nitrates, for example sodium nitrate; nitrites eg sodium nitrite; molybdates eg sodium molybdate; tungstates; silicates eg sodium silicate; benzotriazole, bis-benzotriazole or copper deactivating benzotriazole or tolutriazole derivatives or their Mannich base derivatives; N-acyl sarcosines; N-acylimino diacetic acids; ethanolamines; fatty amines; and polycarboxylic acids, for example, polymaleic acid and polyacrylic acid, as well as their respective alkali metal salts, copolymers of maleic anhydride, eg copolymers of maleic anhydride and sulfonated styrene, copolymers of acrylic acid eg copolymers of acrylic acid and hydroxyalkylated acrylic acid, and substituted derivatives of polymaleic and polyacrylic acids and their copolymers.Moreover, in such completely aqueous systems, the triazole copper corrosion inhibitor used according to the invention may be used in conjunction with dispersing and/or threshold agents eg polymerised acrylic acid (or its salts), phosphinopolycarboxylic acids (as described and claimed in British Patent 1458235), the cotelomeric compounds described in European Patent Application No. 0150706, hydrolysed polyacrylonitrile, polymerised methacrylic acid and its salts, polyacrylamide and co-polymers thereof from acrylic and methacrylic acids, lignin sulphonic acid and its salts, tannin, naphthalene sulphonic acid/formaldehyde condensation products, starch and its derivatives, cellulose, acrylic acid/lower alkyl hydroxyacrylate copolymers eg those described in US Patent Specification No. 4029577, styrene/maleic anhydride copolymers and sulfonated styrene homopolymers eg those described in US Patent Specification No. 4374733 and combinations thereof. Specific threshold agents, such as for example, 2-phosphonobutane-1,2,4-tri-carboxylic acid, acetodiphosphonic acid, hydrolysed polymaleic anhydride and its salts, alkyl phosphonic acid, hydroxyphosphonoacetic acid 1-aminoalkyl-1, 1-diphosphonic acids and their salts, and alkali metal poly-phosphates, may also be used.

Precipitating agents such as alkali metal orthophosphates, carbonates; oxygen scavengers such as alkali metal sulphites and hydrazines; sequestering agents such as nitrilotriacetic acid and its salts; antifoaming agents such as silicones eg polydimethylsiloxanes, distearylsebacamides, distearyl adipamide and related products derived from ethylene oxide and/or propylene oxide condensations, in addition to fatty alcohols, such as capryl alcohols and their ethylene oxide condensates; and biocides eg amines, quaternary ammonium compounds, chlorophenols, sulphurcontaining compounds such as sulphones, methylene bis thiocyanates and carbamates, isothiazolones, brominated propionamides, triazines, phosphonium compounds, chlorine and chlorine-release agents and organometallic compounds such as tributyl tin oxide, may be used.

The compounds of formula I combine excellent copper deactivation properties with good solubility in aqueous- and oil-based substrates.

The following Examples further illustrate the present invention. All parts and percentages given therein are by weight. Examples 1 and 2 are included for the purposes of comparison only.

Examples 1 to 17 A 0.006% solution of a test compound of formula (I) is prepared in water containing 0.132 g/l MgS04.7H2O and 0.68 g/l CaCl2.6H2O (water as used in DIN 51360 test), and the pH of the solution is adjusted to 8.5 with sodium hydroxide.

A piece of copper foil (20 x 50 x 0.1 mm) is cleaned by rubbing it with cotton wool soaked with water and powdered pumice, dried and weighed. It is then fully immersed in 50 ml of the solution so prepared contained in a 60 ml bottle fitted with a screw cap. The bottle is then placed for 24 hours in an oven maintained at 70 C. At the end of this time, the strip is removed, washed and dried and its colour is recorded (using the ASTM D130 colour ranking). It is then immersed for 15 seconds in 5N hydrochloric acid at 20 C, washed, dried and reweighed.

The results are summarised in Table l: Table I

I Exatiple I Ccmpourxi of formula I I Test Results I Example ~~~~~~~~~~~~~~~~~~~~~~~~~ I I I I Weight loss I Metal Appearance I Solution I I I R1 i R2 I (mg) I and rating I AFçearance I I I----- ------------- I I - I - ~l~~~~~~ I------------------ l~ I - I | CONTROL I 4.6 1 4D I Colourless I I 1 I H I | H I 1.0 1 10% surface I Colourless I I i I II pale green I I 2 I SH I | H | H | 0.3 I purple stains I 1 3 I H I C2H5 1 0.2 1 1B I Colourless I 1 4 I H I n-C4H9 1 0.3 1 1B I colourless I I 5 I H I | i-C4Hg I 0.1 I 1B I 1 6 I H n-C6H13 1 0.4 1 1B I Colourless I 1 7 I H I nC7H13 n- q 0.3 I 0.3| 1B I Colourless I 1 8 |I H I Ph 1 0.2 1 1A I Colourless I 1 9 t H I CH2Ph I 0.2 1 1B I Colourless I 1 10 1 H C-C6H11 I 0.1 I 1B I Colourless I I I I I I I 11 I H I 1 I 0.3 1 1B I Colourless I I I1 -N I I I I I I I I I I I I I 1 12 I H I HN-N I 1 0.5 |1 1B I Colourless I I I I 1 I I l I NN CH2CH2- I i I I I I I 1 13 I SH t C2H5 I 0.1 I 1B I Colourless I 1 14 I SH |n-C4Hg 1 0.2 1 1B I Colourless I I 15 I SH I i-C4Hg I 0.1 I IB I | Colourless I 1 16 1 SH I n-C6H13 1 0.4 1 1B I Colourless I I 17 I H I 4-N02C#% 1 0.2 I iB I Colourless I I I 17 I I I 4-N02C6H4 ~~~~~~~~0.2 1 1B |ColourlessI ~~~~~~~ On the ASTM D130 rating, 1 represents zero to slight tarnish, 2 represents moderate tarnish, 3 represents dark tarnish and 4 represents corrosion. The designations A,B and D indicate shadings within the numerical gradings.

Examples 18 to 23 A 0.2% solution of a test compound of formula I is prepared in an antifreeze formulation comprising: Component wt% Borax 3% triethanolamine 2.9% Phosphoric acid 1.1% Glycol 93% The 0.2% test formulation is then diluted to 33% v/v with ASTM D1384 water, thus giving a test compound concentration of 666ppm.

A 3"x0.5" (7.62cmx 1.27cm) cleaned, preweighed copper foil strip is placed in the solution, through which air is passed at a rate of Il/hour whilst the temperature of the solution is maintained at 78-82 C for 48 hours.

On completion, the copper strip is taken from the solution, washed with deionised water, then immersed in a 5N hydrochloric acid solution at 200C for 15 seconds. The copper strip is then washed and reweighed.

The appearance of both the test solution and copper strip is recorded and the weight loss is expressed in mg.

The results are set out in Table II.

Table II

I Example I Compound of formula I I Test Results I I I I I I-I IE2 I Weight loss I Metal Appearance Solution I I I R1 I I (mg) I and rating I Appearance I I- I----II-------------------I ---------- I---------------I-I I- I I - |I #NTTOL 1 33 1 Green deposit I Green I I I I I I I 18 |I |n-C6H13 I 1.8 I 2B I Colourless I 1 19 I H I Ph I I I I 1 20 |I H I CH2Ph 1 1.6 1 1B I Colourless I I I I I I I 1 21 |H |HIN I 1.1 I 1B g Colourless I I I l#' I I I I N N cH2CH2- I I I I I I I I I I I 1 22 I SH I n#H9 SH |n-C4Hg|1.3 1 1B I Colourless I I 23 I SH I n#H13 I 0.1 I iB I Colourless I 1 23| I | nC6H13 I 0.1 1 1BI Colourless Examples 24 to 28 Two clean, pre-weighed copper coupons (50mm x 25mm x 1 mm) are suspended in 200ml of a 500ppm sodium chloride solution in distilled water at pH 7 containing the desired amount of compound of formula (I).

The test is then run for 65 hr+ 1 hr at 400C with aeration rate of 500 ml/min air, any evaporative loss being made up with distilled water.

After cleaning the weight losses of the two metal coupons are determined and the corrosion rate calculated in mg/dm2/day (mdd).

The results are set out in Table Ill.

Table III

I Example I Compound of formula I I Test Results I l I IConcentrationlCorrosion Rate I IR1 1 R2 g (ppm) I (mdd) 1---------1-----1----------------------- I I I I I I - I CONTROL |I 1 13.48 1 24 I H I -Ph I 10 1 0.22 1 25 1 SH I n-C4H9 1 10 1 0.87 1 26 |I H I n-C6H13 1 10 1 0.22 1 27 |H H I -CH2Ph 1 10 1 0.51 1 28 |H |H I RN----N 1 10 1 1.88 I I N I CH2CH2 Examples 29 to 32 A 0.05% solution of the test compound of formula (I) is prepared in a turbine quality mineral oil containing 50ppm of- added, dissolved sulphur.

A copper strip (60x lOx lmm) is polished with 100 grade silicon carbide grit which has been picked up on cotton wool wetted with petroleum ether. The polished strip is then immediately totally immersed in the prepared solution, which is maintained at 1000C for 2 hours. After this time, the strip is removed, washed with petroleum ether, dried and its colour is compared with those of the ASTM D130 Copper Strip Corrosion Standard Chart.

The results are summarised in Table IV.

Table IV

I i Compound of formula I I I Example I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ g I Rating I R1 I R2 I I - I Blank (Control) I I 3B I I 2q I H I | phenyl I 1A l 30 1 H I cyclohexyl I 1B I I I i 31 H I | benzyl I 1B l Examples 32 to 34 3,3'-ethylene-bis(1,2,4-triazoline-5-thione) (1 1.4g; 0.05 mole) is added in small portions to a stirred mixture of conc. nitric acid (10 ml) and water (20 ml) containing sodium nitrite (0.05g) at 45-50 C. After complete addition, the mixture is cooled on ice and neutralised with 50% NaOH solution. Upon neutralisation, a white solid, 3,3'-ethylene-bis-1,2,4-triazole precipitated and is filtered off, washed with a small quantity of water and then dried in vacuo.

Yield=4.2g; mp=241-3 C 'H nmr (d6-Me2SO) : b3.15 (s,4H); 8.1 (s,2H); 10-11 (broadened peak, 2H) 13C nmr (d6-Me2SO) : d26.2, 148.8, 159.1 Using analogous procedures, 3,3'- [ 1,3-propylene ] -bis(1,2,4-triazole m. point 135-400C and 3,3'- [ 1,4-butylene ] -bis(1,2,4-triazole) m. point 236-9 C are prepared.

Claims

1. A method of inhibiting the corrosion of copper or of a metal containing copper, comprising contacting the surface of the copper, or metal containing copper, with a corrosion-inhibiting amount of a triazole compound having the formula l:

wherein R1 is H or SH; and R2 is C2-C20 straight- or branched-chain alkyl, C5-C12 cycloalkyl, C7-C13 aralkyl, optionally substituted C6 or C10 aryl, pyridyl or a residue of formula ll:

or (b) (R2) may be a residue X in which X has its previous significance or (c) R2 may be a C1-C8 alkylene residue optionally substituted by a heteroatom and having the formula X-alkylene in which X has its previous significance.

2;: A method according to claim 1 wherein the triazole compound has the formula IA:

in which R2' is C2-C20 alkyl, phenyl, benzyl or X-alkylene (C1-C8)- wherein X is as defined in claim 1.

3. A method according to claim 2 wherein R2, is C4-C10 alkyl, phenyl, benzyl or X-alkylene (C1-C2)- in which X is as defined in claim 1.

4. A method according to claim 1 wherein the triazole compound has the formula IB:

in which R2" is C2-C20 alkyl.

5. A method according to claim 4 wherein R2" is C4-Cro alkyl.

6. A composition comprising a substrate, in contact with copper, or a metal containing copper, and a copper corrosion-inhibiting amount of a compound of formula I, as defined in claim 1.

7. A composition according to claim 6 wherein the amount of the compound of formula I is from 0.0001% to 5% by weight, based on the total weight of the substrate.

8. A composition according to claim 6 or 7 wherein the substrate is a functional fluid.

9. A composition according to claim 8 wherein the functional fluid is a lubricant, a hydraulic fluid; an oil-in-water or water-in-oil system; metal working fluids with a mineral oil or aqueous base; an engine coolant system based on water, aqueous glycol, or ethylene glycol (or propylene glycol)/methanol; or a transformer or switch oil.

10. A composition according to claim 8 or 9 wherein the functional fluid is oil-based and, in the compound of formula I, R1 is H and R2 is an oleophilic group.

11. A composition according to claim 10 wherein R2 is a C2-C,O alkyl group, a C7-C,3 aralkyl group or a C5-C12 cycloalkyl group.

12. A composition according to claim 8 or 9 wherein the functional fluid is an aqueous, glycol or water/glycol fluid and, in the compound of formula I, R1 is H or SH and R2 is C4-C7 alkyl, C6 or C10 aryl, C7-C13 aralkyl or a residue of formula X-(CH2)n- in which X is as defined in claim 1 and n is O or 1 to 8.

13. A composition according to any of claims 8 to 12 wherein the functional fluid is oilbased and contains one or more antioxidants, metal deactivators, further corrosion or rust inhibitors, viscosity-index improvers, pour-point depressants, dispersants/surfactants or anti-wear additives.

14. A composition according to any of claims 8 to 12 wherein the functional fluid is aqueous-based and contains one or more antioxidants, other corrosion- or rust inhibitors, metal deactivators, extreme-pressure or anti-wear additives, complexing agents, precipation inhibitors, biocides, buffering agents or anti-foams.

15. A composition according to claim 6 or 7 wherein the substrate is industrial cooling water, an aqueous air-conditioning system, a steam-generating system, a sea-water evaporator system, a hydrostatic cooker, or an aqueous closed-circuit heating or refrigerant system.

16. A composition according to claim 16 wherein the substrate contains one or more further corrosion inhibitors; dispersing and/or threshold agents; precipitating agents; oxygen scavengers; antifoaming agents; or biocides.

17. A method according to claim 1 substantially as described with reference to any of Examples 3 to 31.

18. Composition according to claim 6 substantially as described with reference to any of Examples 3 to 31.

19. 3,3'-Ethylene-bis(1 ,2,4-triazole).

20. 3,3'- [ 1 ,3-Propylene ] -bis-(1 2,4-triazole).

21. 3,3'- [ 1 ,4-Butylene ] -bis-( 1 ,2,4-triazole).