GB687380A - Process for the purification of alcohols - Google Patents

Abstract

A process for the purification of an alcohol comprises bringing the alcohol which has received preliminary purification by fractional distillation into intimate contact with one or more ion exchange resins. Atmospheric temperature and pressure or elevated pressure and/or temperature may be employed. The alcohol may be mixed with the resin and filtered or passed through a bed of resin and the latter may be regenerated if an anion-exchange resin by flushing with a dilute solution of alkaline material such as sodium hydroxide, ammonium hydroxide or sodium carbonate whilst if a cation exchange resin by washing with a dilute solution, e.g. of hydrochloric or sulphuric acid. Anion- and cation-exchange resins may be used together or consecutively. Before or after the treatment the alcohol may be hydrogenated or refluxed with caustic alkali or permanganate. Isopropanol produced by the catalytic hydration of propylene may be fractionated, refluxed with potassium permanganate or other oxidizing agent such as sodium hypochlorite, hydrogen peroxide, sodium chromate or dichromate before treatment with the ion exchange resin. Representative anion-exchange resins are those of the phenol-formaldehyde-polyamine type, e.g. prepared by condensing phenols with formaldehyde to form intermediate water-soluble condensates containing methylol groups and further reacting with polyamines and heating, or the products obtained by condensation of aliphatic polyamines with polyhalogen derivatives of hydrocarbons. Representative of cation-exchange resins which may be used are phenol-formaldehyde sulphonic acid resins, a carboxylic acid resin and a sulphonated cross-linked polystyrene resin. Suitable commercial resins mentioned are "Amberlite" (Registered Trade Mark), IR-4B, IRA-400, IR-100, IRC-50, IR-120 and "Ionac" A-300, A-293-M, C-200 and C-212. In examples: (I) isopropanol, prepared by the hydration of propylene in the presence of a sulphuric acid catalyst is successively fractionated and passed through "Amberlite" IR-4B freshly regenerated with sodium hydroxide solution. A heart cut from the fractionated product is diluted with water and the odour compared with a solution of untreated isopropanol; (II) a similar process is carried out after treating the starting material with potassium permanganate. Similar runs were made using the other commercial resins mentioned. The process may be applied to other alcohols, e.g. ethanol or other aliphatic monohydric alcohols produced by catalytic hydration of olefines. Specification 489,173 is referred to.