Patent GB-725570-A (GB)
Title: Improvement in hydroperoxide coupling process
Filed: 1953-02-03
Abstract: A nylon type resin is formed by polymerization in the known manner of a salt formed from sebacic acid or another alkanedioic acid and 2,13-diaminotetradecane which can be obtained by reductive amination of 2,13-tetradecanedione prepared by subjecting 1-methylcyclohexyl hydroperoxide in a homogeneous reaction mixture containing an inert organic diluent to the action of a ferrous salt (see Group IV (b)).ALSO:2,13-Tetradecanedione is prepared by a process in which 1-methylcyclohexyl hydroperoxide in a homogeneous reaction mixture containing an inert organic diluent is subjected to the action of a ferrous salt.  Organic solvents mentioned are benzene, cyclohexane, methylcyclohexane and methanol.  Methylcyclohexane is preferred since methylcyclohexyl hydroperoxide may be prepared by reaction between oxygen and methylcyclohexane, thus producing a suitable solution for conversion to the diketone.  Iron may be extracted from the crude reaction product with water containing an acid of which the ferric salt is more soluble in the aqueous than in the non-aqueous phase, e.g. sulphuric, phosphoric formic, hydroxyacetic or oxalic acid. Suitable ferrous compounds for use when a hydrocarbon diluent is present include ferrous salts of long chain alkanoic acids such as the caproate, the heptanoate the oleate and the stearate.  Long chain alkanoic acid liberated from a ferric salt may be separated from the non-aqueous phase by distillation or reaction with sodium hydroxide. The aqueous ferric iron may be reduced by catalytic hydrogenation and after reaction with the sodium alkanoate obtained above, may be extracted with the nonaqueous medium.  In examples, 1-methylcyclohexyl hydroperoxide is added to a benzene solution of ferrous heptanoate, iron is precipitated from the reacted mixture and heptanoic acid is extracted with aqueous sodium hydroxide and 2,13-tetradecanedione is obtained on distillation of the benzene layer (1), ferrous heptanoate is added to a solution of the hydroperoxide in benzene in a similar process (2); a solution of ferrous heptanoate in methylcyclohexane is employed in a process similar to (1) (3); in a process similar to (1) iron is extracted from the reaction mixture with dilute sulphuric acid and heptanoic acid is extracted from the benzene layer with aqueous sodium carbonate (4); a methanol solution of crude 1-methylcyclohexyl hydroperoxide obtained by treating heated methylcyclohexane with air under pressure in a continuous process, separating the hydroperoxide by adsorption on activated alumina and subsequently washing out with methanol, is added to a methanol solution of ferrous sulphate and the reacted mixture is concentrated, diluted with water and extracted with ether (5); a solution of ferrous heptonoate in methylcyclohexane is added to a solution of 1-methylcyclohexyl hydro peroxide in methylcyclohexane prepared as in (5).  Iron and heptanoic acid are separated from the reacted mixture by treatment with aqueous sulphuric acid and sodium hydroxide solutions.  The iron salt solution is hydrogenated using a palladium catalyst and on mixing with the aqueous sodium heptanoate and methylcyclohexane a solution of ferrous heptanoate in the latter results which is separated and recycled with further methylcyclohexyl hydroperoxide in methylcyclohexane (6).  For comparison an aqueous methanol reaction medium is employed in a process similar to (5). Distributions of ferrous iron from ferrous salts of heptanoic, caproic and valeric acids between aqueous phases and methylcyclohexane under conditions similar to those in (1) are summarized in Table 1. 2,13-Tetradecanedione is oxydized to sebacic acid by nitric acid at elevated temperatures using cupric nitrate and ammonium metavanadate as catalysts.  Oxides of nitrogen generated may be reoxydized, reabsorbed in water and recycled.  The product is obtained by distilling off nitric acid and cooling the residue.  Mother liquors may be fed back to the oxydizer.  Sebacic acid may be obtained by oxidation with air optionally using an organic diluent such as acetic acid, and cobalt or manganese compounds as catalysts.  Oxidation with sodium hypochlorite gives dodecanedioic acid. 2,13-Tetradecanedione is converted to 2,13-diaminotetradecanediamine. by reductive amination and this amine may be converted by forming a salt with an alkanedioic acid, e.g. sebacic acid and polymerizing, to a nylon type resin.