Patent GB-687142-A (GB)
Title: Improvements in and relating to the production of organic oxygen-containing compounds
IPC: C07C69/80
Filed: 1949-09-12
Abstract: Esters are made by esterifying an alcohol produced by the steps: carbonylating at elevated temperature and pressure in the liquid phase in the presence of a cobalt catalyst in suspended or dissolved form a mixture comprising alkenes and substantially free from hydroperoxides or unsaturated alcohols derived from them, which mixture has been obtained by removing from commercially available olefines, which are themselves substantially free from the aforesaid hydroxy compounds, alicyclic monoolefines and/or di- or poly-enes which readily yield hydroperoxides, or by treating such olefines with an oxidation inhibitor free from nitrogen to minimize hydroperoxide formation; and thereafter hydrogenating the carbonylation product. The removal of the objectional compounds is preferably effected by fractional distillation, other specified methods being azeotropic and extractive distillation and solvent extraction.  With alkenes obtained by cracking processes the removal is preferably effected immediately on production.  The process gives esters of better colour.  The use of inhibitors does not give quite such good results. Inhibitors may be used in amounts of 200-2,000 p.p.m. and they may be added to the alkenes immediately they are produced or at intervals during storage.  2,4-Dimethyl-6-butyl phenol is a specified inhibitor.  If hydroperoxides or compounds derived therefrom are present in the mixture to be carbonylated they are preferably eliminated, e.g. by distillation, when an inhibitor is to be used for the carbonylation.  The undesirable alicyclic compounds are distinguished by much higher densities and refractive indices than corresponding aliphatic compounds.  These characteristics are also higher for aliphatic di- and poly-enes. The starting material should contain not more than 5 m.g. of peroxide oxygen, preferably less than 2 m.g., per litre.  Alkene feeds specified are C4-C18, especially C4-C12 mono-olefines and particularly C6-C8 olefines obtained by cracking, e.g. paraffin wax, and in particular alpha-olefines. Cobalt salts specified as catalysts are the naphthenate, acetate, laurate, hexahydrobenzoate or 3,5,5-trimethylhexoate.  Conditions specified for the production of the alcohols are those usual in the oxo-synthesis.  Esters specified are phthalates, sebacates, adipates, maleates and phosphates.  They may be made by reacting an acid anhydride with the alcoholic product in an inert medium, e.g. benzene or toluene, preferably in the presence of an acid catalyst in the absence of water.  In an example, a C6-C8 alkene mixture is fractionally distilled to remove compounds of high density and refractive index and the product is stabilized with 2,4-dimethyl-6-butyl phenol before carbonylation, hydrogenation and esterification with phthalic anhydride when the ester obtained is shown to be of better colour than that made from the untreated alkene feed.  Normal esters of normal heptanol and 2-methyl hexanol are made from normal hexene. Specifications 667,109, 684,334 and 684,958 are referred to.