Sulfonium compounds as corrosion inhibitors in aqueous acidic cleaning solutions
AssigneeThe Dow Chemical Company
InventorsWayne W. Frenier, William J. Settineri
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Abstract
Certain sulfonium salts are herein described which are useful corrosion inhibitors in aqueous acidic cleaning solutions, even in the presence of ferric ions. The sulfonium salts correspond to the following formulas: ##STR1##
Claims25
An aqueous acidic cleaning solution of at least one non-oxidizing inorganic acid having dissolved or dispersed therein a sulfonium salt corresponding to the formula ##STR13## wherein n is 1 or 2;
- each R.sub.1 independently is hydrogen or a hydrocarbyl, a hydrocarbyl whose chain length is interrupted by an atom of oxygen or sulfur, a hydrocarbyloxy or a hydrocarbylthio radical of from 1 to about 24 carbon atoms;
- R.sub.2 is a hydrocarbyl or inertlysubstituted hydrocarbyl radical of from 1 to about 24 carbon atoms, with the proviso that the total aggregate carbon content of R.sub.1 and R.sub.2 is from 7 to about 25;
- R.sub.3 is an alkyl radical of from 1 to 4 carbon atoms or an inertly-substituted alkyl radical of from 2 to 4 carbon atoms, allyl, phenyl or an inertly-substituted phenyl radical;
- or R.sub.2 and R.sub.3 are joined to form a 5-or 6-membered heterocyclic ring, with the proviso that the total aggregate carbon content of R.sub.1, R.sub.2 and R.sub.3 is from 10 to about 25;
- R.sub.4 is alkyl of 4 to about 20 carbon atoms;
- R.sub.5 is methyl or ethyl;
- R.sub.6 is hydrogen, methyl or ethyl;
- q is an integer of from 0 to 8;
- r is an integer of from 0 to 10, with the proviso that the sum of q plus r is equal to or less than 10;
- and A.crclbar. is an anion;
- said sulfonium salt being present in an amount at least sufficient to inhibit the acid-induced corrosion of ferrous metals in contact with said solution and ferric ions.
A process of inhibiting the acid-induced and ferric ion-induced corrosion of metal surfaces in contact with an aqueous acid solution of at least one non-oxidizing inorganic acid, the process comprising incorporating in said acid solution a small but corrosion-inhibiting amount of at least one sulfonium salt corresponding to the formula ##STR14## wherein n is 1 or 2;
- each R.sub.1 independently is hydrogen or a hydrocarbyl, a hydrocarbyl whose chain length is interrupted by an atom of oxygen or sulfur, a hydrocarbyloxy or a hydrocarbylthio radical of from 1 to about 24 carbon atoms;
- R.sub.2 is a hydrocarbyl or inertlysubstituted hydrocarbyl radical of from 1 to about 24 carbon atoms, with the proviso that the total aggregate carbon content of R.sub.1 and R.sub.2 is from 7 to about 25;
- R.sub.3 is an alkyl radical of from 1 to 4 carbon atoms or an inertly-substituted alkyl radical of from 2 to 4 carbon atoms, allyl, phenyl or an inertly-substituted phenyl radical;
- or R.sub.2 and R.sub.3 are joined to form a 5- or 6-membered heterocyclic ring, with the proviso that the total aggregate carbon content of R.sub.1, R.sub.2 and R.sub.3 is from 10 to about 25;
- R.sub.4 is alkyl of 4 to about 20 carbon atoms;
- R.sub.5 is methyl or ethyl;
- R.sub.6 is hydrogen, methyl or ethyl;
- q is an integer of from 1 to 8;
- r is an integer of from 0 to 12, with the proviso that the sum of q plus r is equal to or less than 12;
- and A.crclbar. is an anion;
- said sulfonium salt being present in an amount at least sufficient to inhibit the acid-induced corrosion of ferrous metals in contact with said solution and ferric ions.
An aqueous acidic cleaning solution of at least one non-oxidizing inorganic acid having dissolved or dispersed therein a sulfonium salt corresponding to the formula ##STR15## wherein n is 1 or 2;
- each R.sub.1 independently is hydrogen or a hydrocarbyl, a hydrocarbyl whose chain length is interrupted by an atom of oxygen or sulfur, a hydrocarbyloxy or a hydrocarbylthio radical of from 1 to about 24 carbon atoms;
- R.sub.2 is a hydrocarbyl radical of from 1 to about 24 carbon atoms, with the proviso that the total aggregate carbon content of R.sub.1 and R.sub.2 is from 7 to about 25;
- R.sub.3 is an alkyl radical of from 1 to 4 carbon atoms;
- allyl, phenyl or an inertly substituted phenyl radical;
- or R.sub.2 and R.sub.3 are joined to form a 5- or 6-membered heterocyclic ring;
- with the proviso that the total aggregate carbon content of R.sub.1, R.sub.2 and R.sub.3 is from 10 to about 25;
- R.sub.4 is alkyl of 4 to about 20 carbon atoms;
- R.sub.5 is methyl or ethyl;
- R.sub.6 is hydrogen, methyl or ethyl;
- q is an integer of from 0 to 8;
- r is an integer of from 0 to 10, with the proviso that the sum of q plus r is equal to or less than 10;
- and A.crclbar. is an anion;
- said sulfonium salt being present in an amount at least sufficient to inhibit the acid-induced corrosion of ferrous metals in contact with said solution and ferric ions.
Dependencies are inferred from the claim text.