Patent GB-481795-A (GB)
Title: Improvements relating to the production of oxygenated organic compounds from unsaturated hydrocarbons
IPC: C07C51/14
Filed: 1936-08-15
Abstract: Esters are manufactured by reacting a secondary olefine of the aliphatic or naphthenic series with an aliphatic carboxylic acid at a temperature below 100 DEG  C. in the presence of boron fluoride, titanium tetrachloride or silicon tetrafluoride (which may be in the form of a molecular complex compound) as catalyst.  The reaction may be carried out by dissolving the catalyst in the acid and agitating this solution with the olefine.  A suitable apparatus for use with a gaseous olefine comprises a generator in which boron fluoride is produced, e.g. from sulphuric acid, calcium fluoride and boric acid or sodium borate, and whence it passes through a purifying apparatus to the bottom of a tower down which the acid trickles.  The resulting solution passes to the top of a second tower into which the olefine is led at the bottom and from which the resulting ester-boron fluoride solution passes to the bottom of a third tower down which caustic soda solution flows.  The products are passed to a separator, whence the upper layer of ester passes to a fractionating apparatus and the lower, containing sodium borate, sodium borofluoride, the sodium salt of the carboxylic acid and excess caustic soda, passes to stills for distilling off any dissolved esters and then to apparatus in which it is evaporated to dryness, the residue being used for regenerating the carboxylic acid and boron fluoride.  The reaction may also be carried out by passing the gaseous catalyst through an agitated mixture of the acid and olefine, or by passing a gaseous mixture of the catalyst and olefine into the acid, or by a continuous process by passing secondary olefines containing at least three carbon atoms and aliphatic carboxylic acids into a reaction chamber in the presence of boron fluoride, and continuously withdrawing the ester product.  The process may be applied to the separation of secondary and tertiary olefines from a mixture thereof.  The process may also be combined with the production of ethers by treating the esterboron fluoride solution produced with an alcohol to liberate the ester and form an alcohol-boron fluoride solution, treating this with a tertiary olefine and hydrolyzing the resulting ether-boron fluoride solution to liberate the ether.  The reaction is applicable to secondary olefines below pentene, e.g. propylene and butylene, higher olefines, cyclic olefines, e.g. cyclohexene, or mixtures of olefines, e.g. those obtainable from petroleum products.  In examples, pentene-2 is treated with an acetic acid solution of boron fluoride, yielding sec.-amyl acetate on hydrolysis.  The acetic acid may be replaced by other aliphatic acids, e.g. formic, propionic, butyric, oleic or stearic acid, mixtures obtainable by oxidation of paraffin wax or liquid petroleum distillates, also substituted aliphatic acids and di- or polybasic acids. Specifications 307,802, [Class 2 (iii)], and 442,454 are referred to.  A sample has been furnished under Sect. 2 (5) of cyclohexyl acetate made by the action of acetic acid on cyclohexene in the presence of boron fluoride.