GB348596A - Process for protecting metals from the attack of acids - Google Patents

Abstract

An improvement in or modification of the process claimed in the parent Specification consists in the use of sulphonation products of oily bases which are contained in coal tar, boil at above 240 DEG C. and are insoluble or sparingly soluble in dilute acid, to protect metal against attack by acids. The bases are stated to accumulate in the distillation residues in the rectification of pyridine and quinoline or they may be obtained by neutralizing the extract formed by treating coal tar oils of high boiling-point with acid. In an example a tar oil base, insoluble or sparingly soluble in dilute acid and boiling above 240 DEG C., is stirred, while cooled with ice, with concentrated or fuming sulphuric acid, a sulphonation product soluble in dilute acid being obtained by subsequent heating to 70-90 DEG C. About 140-200 parts by weight of concentrated acid to 100 parts of tar oil base are necessary. The product may be added to the acid used in pickling baths, for cleaning steam boilers &c., or to prevent the corrosion of metal tanks in which the acid is stored or transported. In pickling a foaming agent may be added, e.g. liquorice extract, glycyrrhizic acid or its salts, or saponin.ALSO:Sulphonation products of oily bases which are contained in coal tar, boil at above 240 DEG C. and are insoluble or sparingly soluble in dilute acids, are used to protect metals against attack by acids. The bases are stated to accumulate in the distillation residues in the rectification of pyridine and quinoline or they may be obtained by neutralizing the extract formed by treating coal tar oils of high boiling-point with acid. In an example a tar oil base, insoluble or sparingly soluble in dilute acid and boiling above 240 DEG C., is stirred, while cooled with ice, with concentrated or fuming sulphuric acid, a sulphonation product soluble in dilute acid being obtained by subsequent heating to 70-90 DEG C.ALSO:An improvement in or modification of the process claimed in the parent Specification consists in the use of sulphonation products of oily bases which are contained in coal tar, boil at above 240 DEG C. and are insoluble or sparingly soluble in dilute acid, to protect metal against the attack of acids, e.g. in pickling baths. The bases are stated to accumulate in the distillation residues in the rectification of pyridine and quinoline or they may be obtained by neutralizing the extract formed by treating coal tar oils of high boiling point with acid. In an example a tar oil base, insoluble or sparingly soluble in dilute acid and boiling above 240 DEG C., is stirred, while cooled with ice, with concentrated or fuming sulphuric acid, a sulphonation product soluble in dilute acid being obtained by subsequent heating to 70-90 DEG C. About 140-200 parts by weight of concentrated acid to 100 parts of tar oil base are necessary. The product may be added to the acid used in pickling baths, for cleaning steam boilers &c., or to prevent the corrosion of metal tanks in which the acid is stored or transported. In pickling a foaming agent may be added, e.g. liquorice extract, glycyrrhizic acid and its salts, or saponin.