Patent GB-831068-A (GB)
Title: Improvements in or relating to corrosion inhibitors
IPC: C10L1/26
Filed: 1956-04-16
Abstract: A composition, with reduced corrosivity towards silver and copper, comprises an oil and up to 10% of the reaction product of 1 mol. of 2,5 - dimercapto - 1,3,4 - thiadiazole, 2 to 6 mols. of an aldehyde and 1 to 5 mols. of an organic hydroxy compound.  The oils may be hydrocarbon oils, synthetic hydrocarbon oils such as polymers, e.g. olefin polymers such as polybutenes, polypropylene and mixtures thereof, synthetic lubricating oils of the alkyleneoxide type and other synthetic oils such as the polycarboxylic ester type, e.g. the esters of adipic, sebacic, maleic and azelaic acids.  Fuel oils, insulating oils, greases and non-drying animal and vegetable oils, e.g. lard, tallow and neatsfoot oils, are also mentioned.  The aldehyde may be an aliphatic aldehyde containing from 1 to 20 carbon atoms or an aromatic or heterocyclic aldehyde containing from 5 to 30 carbon atoms and may contain substituents such as alkoxy, hydroxy, mercapto or nitro groups or halogen atoms, examples of aldehydes being formaldehyde, acetaldehyde, benzaldehyde, 2-ethyl hexyl aldehyde, butyraldehyde, caprylic aldehyde, acrylic aldehyde, crotonaldehyde, vinyl acetaldehyde, phenyl acetaldehyde, nitro-benzaldehyde, salicyladehyde, furfural and chloral.  The organic hydroxy compound has the formula ROH where R is either an aliphatic radical containing from 4 to 30 carbon atoms or an aromatic radical containing from 6 to 40 carbon atoms.  It may be an aliphatic alcohol, which may be mono- or polyhydroxy and may contain aryl and heterocyclic groups as well as substituents such as alkoxy, nitro, cyano and alkylthio groups, examples being butyl alcohol, amyl alcohol, octyl alcohol, nonyl alcohol, di-t-amyl cyclohexanol and 2-butyl octanol-1, or it may be an aromatic compound which may have alkyl substituent groups, examples being phenols, such as nonyl phenol, 4 - t - butyl - 2 - alpha - methyl benzyl phenol and 3-pentadecyl phenol, naphthols, ar-hydroxy anthracenes, ar-hydroxy phenanthrenes, and diphenols.  Such compositions are particularly useful for lubricants, motor fuels and heater fuels containing elemental sulphur and/or organic sulphur containing compounds.  The Specification mentions sulphurized terpenes, including monocyclic, bicyclic, and acyclic terpenes and polyterpenes (list given), sulphurized hydrocarbon oils, sulphurized vegetable oils, sulphurized animal oils, sulphurized marine oils, xanthate esters, and organic polysulphides which contain active sulphur.  Other additives mentioned are neutralized sulphur and phosphorus-containing reaction products of a phosphorus sulphide and a hydrocarbon, e.g. polyolefins such as polybutenes and polypropylene.  In examples, 2,5-dimercapto-1,3,4-thiadiazole is reacted with the following combinations of aldehyde and hydroxy compound: formaldehyde and 4-t-butyl-2-alpha-methyl benzyl phenol; formaldehyde and 3-pentadecyl phenol; formaldehyde and nonyl phenol, which are first combined to form nonyl hydroxy-methyl phenol; formaldehyde and nonyl alcohol; formaldehyde and di-t-amyl cyclohexanol; formaldehyde and 2-butyl octanol-1.ALSO:Thiadiazole derivatives are prepared by reaction of 1 mol. of 2,5-dimercapto-1,3,4-thiadiazole, 2 to 6 mols. of an aldehyde containing 1-30 carbon atoms and 1 to 5 mols. of an organic hydroxy compound as hereinafter defined at 25-150 DEG  C.  All three reagents may be interacted together or the aldehyde may be reacted with the mercapto thiadiazole or the hydroxy compound and the resulting product then reacted with the third reagent.  Solvents may be present.  Aldehydes specified are C1-20 aliphatic and C5-30 aromatic and heterocyclic aldehydes which may contain alkoxy, hydroxy, mercapto, nitro, or halogen substituents, e.g. formaldehyde, acetaldehyde, benzaldehyde, 2ethyl hexyl aldehyde, butyraldehyde, caprylic aldehyde, acrylic aldehyde, crotonaldehyde, vinyl acetaldehyde, phenyl acetaldehyde, nitrobenzoaldehyde, salicylaldehyde, furfural and chloral.  The organic hydroxy compounds have the formula ROH where R is a C4-30 aliphatic or C6-40 aromatic radical.  The aliphatic alcohols may be mono- or polyhydric and may contain aryl and heterocyclic groups as well as substituents such as alkoxy, nitro, cyano and alkylthio groups, e.g. butyl, amyl, octyl and nonyl alcohols, di-t-amyl cyclohexanol, and 2-butyl octanol-1. Specified aromatic hydroxy compounds are nonyl-, 4-t-butyl-2-alpha-methyl benzyl-, and 3-pentadecyl phenols, naphthols, ar-hydroxy anthracenes and phenanthrenes, and diphenols. In examples, 2,5-dimercapto1,3,4-thiadiazole is reacted with formaldehyde plus: (i) 4-t-butyl-2-alphamethyl benzyl phenol; (ii) 3-pentadecylphenol; (iii) nonyl phenol; (iv) nonyl alcohol; (v) di-t-amyl cyclohexanol; and (vi) 2-butyl octanol-1. The products may be used as corrosion inhibitors.