the present invention relates generally to corrosion inhibitors , and more particularly to corrosion inhibitors comprising reaction products of a thiol compound and an aldehyde compound and methods of using such inhibitors . the corrosion inhibitors of the present invention may be used to protect metals against acids , heavy brines , and other treatment fluids commonly used in subterranean applications . the corrosion inhibitors of the present invention comprise the reaction products of a thiol compound and an aldehyde compound ; these compounds may be generally described as thioacetals . one skilled in the art will be aware of numerous methods in the prior art for making a thioacetal compound . thiols can be reacted with aldehydes in any ratio to make the desired thioacetal , mixed thioacetal , hemithioacetal , oxathiolane , or mixture thereof . thioacetals suitable for use as the corrosion inhibitors of the present invention include monothioacetals having the general formula : wherein r , r ′ and r ″ may be h and dithioacetals having the general formula : aldehyde compounds suitable for use in the present invention include cinnamaldehyde and its derivatives . suitable aldehydes include α , β - unsaturated aldehydes having the general the formula : a saturated or unsaturated aliphatic hydrocarbon group containing from about 3 to about 12 carbon atoms ; a substituted saturated or unsaturated aliphatic hydrocarbon group containing from about 3 to about 12 carbon atoms and containing one or more non - interfering substituents ; an aryl group , e . g ., phenyl , benzyl or the like ; a substituted aryl group containing one or more non - interfering substituents ; or , a non - interfering substituent per se . hydrogen ; a saturated or unsaturated aliphatic hydrocarbon group containing from 1 to about 5 carbon atoms ; a substituted saturated aliphatic hydrocarbon group containing from 1 to about 5 carbon atoms and containing one or more noninterfering substituents ; an aryl group ; a substituted aryl group containing one or more non - interfering substituents ; or , a non - interfering substituent per se . hydrogen ; a saturated or unsaturated aliphatic hydrocarbon group containing from about 3 to about 12 carbon atoms ; a substituted saturated or unsaturated aliphatic hydrocarbon group containing from about 3 to about 12 carbon atoms and containing one or more non - interfering substituents ; an aryl group ; a substituted aryl group containing one or more non - interfering substituents ; or , a non - interfering substituent per se . the total number of carbon atoms in substituents represented by r 1 , r 2 and r 3 range from 1 to about 16 , preferably from 5 to 10 . the “ non - interfering substituents ” referred to above are those substituents that have no adverse effect on the corrosion inhibition . they include , for example , lower alkyl ( containing from 1 to about 4 carbon atoms ), lower alkoxy ( containing from 1 to about 4 carbon atoms ), halo , i . e ., fluoro , chloro , bromo or iodo , hydroxyl , dialkylamino , cyano , thiocyano , n , n - dialkylcarbamoylthio and nitro substituents . examples of aldehydes suitable for use in the present invention include , but are not limited to : 7 - phenyl - 2 , 4 , 6 - heptatrienal , crotonaldehyde , 2 - hexenal , 2 - heptenal , 2 - octenal , 2 - nonenal , 2 - decenal , 2 - undecenal , 2 - dodecenal , 2 , 4 - hexadienal , 2 , 4 - heptadienal , 2 , 4 - octadienal , 2 , 4 - nonadienal , 2 , 4 - decadienal , 2 , 4 - undecadienal , 2 , 4 - dodecadienal , 2 , 6 - dodecadienal , citral , 1 - formyl -[ 2 -( 2 - methylvinyl )]- 2 - n - octylethylene , cinnamaldehyde , dicinnamaldehyde , p - hydroxycinnamaldehyde , p - methylcinnamaldehyde , p - ethylcinnamaldehyde , p - methoxycinnamaldehyde , p - dimethylaminocinnamaldehyde , p - diethylaminocinnamaldehyde , p - nitrocinnamaldehyde , o - nitrocinnamaldehyde , o - allyloxycinnamaldehyde , 4 -( 3 - propenal ) cinnamaldehyde , p - sodium sulfocinnamaldehyde , p - trimethylammoniumcinnamaldehyde sulfate , p - trimethylammoniumcinnamaldehyde o - methylsulfate , p - thiocyanocinnamaldehyde , p -( s - acetyl ) thiocinnamaldehyde , p -( s — n , n - dimethylcarbamoylthio ) cinnamaldehyde , p - chlorocinnamaldehyde , 5 - phenyl - 2 , 4 - pentadienal , 5 -( p - methoxyphenyl )- 2 , 4 - pentadienal , 2 , 3 - diphenylacrolein , 3 , 3 - diphenylacrolein , α - methylcinnamaldehyde , β - methylcinnamaldehyde , α - chlorocinnamaldehyde , α - bromocinnamaldehyde , α - butylcinnamaldehyde , α - amylcinnamaldehyde , α - hexylcinnamaldehyde , 2 -( p - methylbenzylidine ) decanal , α - bromo - p - cyanocinnamaldehyde , α - ethyl - p - methylcinnamaldehyde , p - methyl - α - pentylcinnamaldehyde , 3 , 4 - dimethoxy - α - methylcinnamaldehyde , α -[( 4 - methylphenyl ) methylene ] benzeneacetaldehyde , α -( hydroxymethylene )- 4 - methylbenzylacetaldehyde , 4 - chloro - α -( hydroxymethylene ) benzeneacetaldehyde , α - nonylidenebenzeneacetaldehyde , mixtures thereof , and the like . thiol compounds suitable for use in the present invention include thiols and their derivatives . thiols are compounds having the general formula : examples of suitable thiols suitable for use in the present invention include , but are not limited to , thiosorbitol , hydrogen sulfide , methanethiol , thioethanol , 1 - thio - 2 - butanol , 1 , 2 - ethanedithiol , 1 , 3 - propanedithiol , 2 - aminoethanethiol , 2 - mercaptobenzothiazole , 2 - mercaptothiazoline , glycol dimercaptoacetate , mercaptosuccinic acid , thioglycerol , thiolactic acid , cysteine , 6 - amino - 3 - mercaptothiazole , 6 - ethoxy - 2 - mercaptobenzothiazole , glycerol monothioglycolate , monoethanolamine thioglycolate , methyl thioglycolate , isooctyl thioglycolate , ethyl thioglycolate , 2 - ethyl hexyl thioglycolate , and thioglycolic acid . some embodiments of the present invention comprise combining the reaction product thioacetals with a traditional corrosion inhibitor such as cinnamaldehyde , acetylenic alcohols , fluorinated surfactants , quaternary derivatives of heterocyclic nitrogen bases , aromatic compounds , formamides , combinations of such compounds used in conjunction with iodine ; quaternary ammonium compounds ; and combinations thereof . the quaternary ammonium compounds which function as corrosion inhibitors and can be used in accordance with the present invention have the general formula : wherein each r is the same or a different group selected from long chain alkyl groups , cycloalkyl groups , aryl groups or heterocyclic groups , and x is an anion such as a halide . the term “ long chain ” is used herein to mean hydrocarbon groups having in the range of from about 12 to about 20 carbon atoms . examples of quaternary ammonium compounds which can be included in the corrosion inhibiting composition of this invention are n - alkyl , n - cycloalkyl and n - alkylarylpyridinium halides such as n - cyclohexylpyridinium bromide or chloride , n - alkyl , n - cycloalkyl and n - alkylarylquinolinium halides such as n - dodecylquinolinium bromide or chloride , and the like . the traditional corrosion inhibitor used may be included in corrosion inhibiting mixture in an amount in the range of from 0 . 5 % to about 80 % by weight of total corrosion inhibiting mixture , preferably from about 1 % to about 45 % by weight of total corrosion inhibiting mixture . along with such traditional corrosion inhibitors , embodiments of the present invention may further comprise components commonly used in corrosion inhibiting formulations such as acetylenic alcohols , mannich condensation products ( such as those formed by reacting an aldehyde , a carbonyl containing compound and a nitrogen containing compound ), unsaturated carbonyl compounds , unsaturated ether compounds , formamide , formic acid , formates , other sources of carbonyl , iodides , terpenes , and aromatic hydrocarbons . corrosion inhibitor activators function to activate corrosion inhibitor components such as quaternary ammonium compounds so that they function as corrosion inhibitors . examples of such corrosion inhibitor activators which can be used in accordance with the present invention are cuprous iodide ; cuprous chloride ; antimony compounds such as antimony oxides , antimony halides , antimony tartrate , antimony citrate , alkali metal salts of antimony tartrate and antimony citrate , alkali metal salts of pyroantimonate and antimony adducts of ethylene glycol ; bismuth compounds such as bismuth oxides , bismuth halides , bismuth tartrate , bismuth citrate , alkali metal salts of bismuth tartrate and bismuth citrate ; iodine ; iodide compounds ; formic acid ; and mixtures of the foregoing activators such as a mixture of formic acid and potassium iodide . when a corrosion inhibitor activator is included in a composition of this invention , it is generally present in an amount in the range of from about 0 . 1 % to about 10 . 0 % by weight of the composition . other embodiments of the present invention comprise combining the reaction product thioacetals with a surfactant that acts , inter alia , to improve the solubility and performance of the thioacetal . any surfactant compatible with the thioacetal may be used in the present invention . such surfactants include , but are not limited to , ethoxylated nonyl phenol phosphate esters , non - ionic surfactants , cationic surfactants , alkyl phosphonate surfactants , linear alcohols , nonylphenol compounds , alkyoxylated fatty acids , alkylphenol alkoxylates , ethoxylated amides , ethoxylated alkyl amines , and mixtures thereof . examples of mixtures of one or more cationic and nonionic surfactants are described in u . s . pat . no . 6 , 311 , 773 issued to todd , et al ., the relevant disclosure of which is incorporated herein by reference . the surfactant or surfactants used may be included in corrosion inhibiting mixture in an amount in the range of from 0 % to about 50 % by weight of total corrosion inhibiting mixture . other embodiments of the present invention comprise combining the reaction product thioacetals with a solvent . a solvent may be particularly useful in cases in which the reaction product thioacetal is a solid at handling conditions . any solvent that is compatible with the thioacetal and other components of the corrosion inhibiting mixture is suitable for use in the present invention . suitable solvents include , but are not limited to , alcohols , glycols , dimethyl formamide and n - methyl pyrrolidone , water , and combinations thereof . the solvent used may be included in corrosion inhibiting mixture in an amount in the range of from 0 % to about 60 % by weight of total corrosion inhibiting mixture . to facilitate a better understanding of the present invention , the following examples of some of the preferred embodiments are given . in no way should such examples be read to limit the scope of the invention . one method of forming thioacetals corrosion inhibitors of the present invention involves combining a cinnamaldehyde compound with a thiol compound in the presence of an acid . sample 1 was formed by placing cinnamaldehyde in glacial acetic acid and adding 2 . 2 equivalents of thioethanol , 0 . 05 equivalents of ρ - toluenesulfonic acid was also added to the reactive mixture to speed up the reaction . the thioacetals corrosion inhibitors were tested on metal coupons free of surface contaminants and scale . to ensure that the coupons were properly prepared , they were soaked in acetone to remove any material remaining on the metal from manufacturing and then visually inspected for burrs or other loosely attached metal . next , the coupons were bead blasted using coarse glass beads to remove contaminants including oxidation products and material lodged in areas where the coupon surfaces may be irregular . the coupons were then used immediately . to test the activity of the corrosion inhibitors of the present invention , a weighed coupon was suspended from a teflon ® holder inside a cell constructed of glass . the cell was then placed in an autoclave , 100 ml of 15 % hcl was poured into the cell , and then enough kerosene was added such that the coupon was sufficiently submerged . finally , the contents of the test cells were infused either with traditional corrosion inhibitors , no inhibitor , or an above - described thioacetal inhibitors of the present invention . in each case in which inhibitor was added , 0 . 00378 mol was used . the autoclave was then pressurized to 1000 psig using nitrogen , heated to 225 ° f . for a total contact time of 3 hours . the results were as follows : thus , the corrosion inhibitors of the present invention provide improved corrosion inhibition as opposed to the prior art . samples 1 through 5 are corrosion inhibitors of the present invention and are further described below : therefore , the present invention is well adapted to carry out the objects and attain the ends and advantages mentioned as well as those that are inherent therein . while numerous changes may be made by those skilled in the art , such changes are encompassed within the spirit and scope of this invention as defined by the appended claims .