A process for separating sulphuric acid from mixtures of sulphuric acid and sulphuric acid esters

摘要

501,087. Sulphuric acid esters. NAAMLOOZE VENNOOTSCHAP DE BATAAFSCHE PETROLEUM MAATSCHAPPIJ. Nov. 25, 1937, No. 32546. Convention date, Dec. 24, 1936. [Class 2 (iii)] Sulphation products comprising mixtures of sulphuric acid and sulphuric acid esters are freed from the sulphuric acid by washing them with water in the presence of organic compounds containing only carbon, hydrogen and oxygen and having from 5 to 15 carbon atoms in the molecule. The sulphation products may be derived from unsaturated hydrocarbons, alcohols or unsaturated carboxylic acids. Specified solvents are hexyl, heptyl, decyl, benzyl and terpene alcohols and aliphatic ketones such as methyl hexyl ketone and methylheptylketone. These solvents may be used in admixture with other solvents for example those having less than 5 carbon atoms such as methylethylketone. In an example, secondary heptyl alcohol is added to a reaction mixture obtained by treating a distillate of cracked paraffin wax with sulphuric acid of 90 per cent concentration and excess sulphuric acid is removed by washing five times with water. Neutralization may be effected with alkali hydroxide in the presence of the solvent which facilitates the hydrolysis of the normal dialkyl sulphates. After diluting with water, the unattacked olefines and the solvent are extracted with a solvent such as benzine. The remaining aqueous solution may be evaporated to give the pure alkali alkylsulphate. In a further example, before washing in the presence of heptyl alcohol most of the acid is removed by means of water. The dialkylsulphates and the polymers may also be removed by extraction with benzine before the washing process with water in the presence of the oxygen containing solvents to remove the excess sulphuric acid. The process may be effected continuously. The reaction mixture together with the solvent may be passed in countercurrent with water, or the reaction mixture may be introduced into an extraction column and water passed into the top thereof. A sulphuric acid solution may then be drawn off at the top and a sulphuric acid free mixture of solvent and alkyl sulphuric esters withdrawn from the bottom.