| 摘要 |
Sulphonated compositions are obtained by treating naphthalene, preferably crude naphthalene or pure naphthalene to which the normally occurring impurities have been added, with 2-4 times its weight of concentrated sulphuric acid at 75-87 DEG C. for a time which ranges from 20 hours at 75 DEG C. to 2 hours at 80 DEG C. or 1 hour at 85 DEG C. according to the temperature used, and stopping the reaction by cooling. The preferred temperature is from 78 DEG to 82 DEG C., when the reaction period is two hours. A suitable starting material is crude gas-works naphthalene. The resulting solution of the sulphonation product in an excess of sulphuric acid is used as a de-rusting agent or rust preventor. An example is given in which 70 parts of concentrated sulphuric acid are heated at 80 DEG C. for 2 hours with 30 parts of commercial crude naphthalene.ALSO:Metal-cleaning compositions comprise (1) a product obtained by treating naphthalene, preferably crude naphthalene or a purified naphthalene to which normally occurring impurities have been added, with 2-4 times its weight of concentrated sulphuric acid at 75-87 DEG C. for a time ranging from 20 hours at 75 DEG C. to 1 hour at 85 DEG C., either (2) in admixture with diatomaceous earth, pumice meal or finely ground quartz sand or (3) emulsified in a liquid, e.g. in a 5 per cent. solution of a hydroxyethyl ethyl cellulose acetate in water. Rust inhibitors comprise a solution of the above naphthalene sulphonic acid composition in a mixture of water, nitric acid and hydrochloric acid made into a paste with a carrier such as petroleum jelly, the solution forming 1-10 per cent. of the paste.ALSO:A metal cleaning solution comprises a composition obtained by reacting napthalene with 2-4 times its weight of concentrated sulphuric acid, at 75-87 DEG C., for a time ranging from 20 hours at 75 DEG C. to 1 hour at 85 DEG C. (see Group IV (b)) in admixture with water, concentrated nitric acid and concentrated hydrochloric acid. |
