| 摘要 |
A process for making polyesters comprises oxidizing an alicyclic ketone having at most 8 carbon atoms in the ring to a self-condensed o -hydroxy acid, the oxidizing agent being formed by electrolysing an aqueous solution containing bisulphate ions to convert at least some of the ions to perdisulphate ions and allowing the perdisulphate ions to hydrolyse forming permonosulphate ions. The alicyclic ketone is added to the oxidizing solution to form the self-condensed o -hydroxy acid with reduction of permonosulphate to bisulphate, the acid is separated and the remaining bisulphate solution is recycled to the electrolysis cell.ALSO:Self-condensed o -hydroxy acids consisting of lactones, and linear poly-esters are made by oxidizing an alicyclic ketone having at most 8C atoms using an aqueous solution containing permono-sulphate ions which oxidize the ketone, and become reduced to bisulphate ions. The solution of bisulphate ions is recycled to an electrolytic cell where per-disulphate ions are formed which is then allowed to hydrolyze to per-mono-sulphate ions and the ketone is then added. A solution containing ammonium sulphate and sulphuric acid with a trace of ammonium thiocyanate, is electrolyzed forming ammonium per-disulphate [(NH4)2S2O8]; this hydrolyzes spontaneousl to per-mono-sulphate containing 2.31 mols of active oxygen of which 2.07 mols. are per-mono-sulphate. The ketone e.g. cyclohexanone is added gradually before further hydrolysis occurs yielding bisulphate and H2O2. The reaction temperature is maintained at 50 DEG C. The product separates into two layers. The aqueous layer is extracted with a solvent e.g. a ketone or alcohol, and the extracted material added to the upper layer. The total product is 0.53 mol. of 6-hydroxy caproic acid and its self-condensed derivative with minor amounts of cyclohexanone and adipic acid. The aqueous electrolyte is fixed from residual organic matters by filtration through an absorbent e.g. activated charcoal, and recycled to the electrolytic cell to regenerate per-disulphate. In another example, cycloheptanone is oxidized to form poly-oenanthate ester. The lactone may be convected to capiolactain by heating under pressure with ammonia. The formation and consumption of per-mono-sulphate during addition of the ketone should be monitored e.g. by measuring the oxidation potential of the electrolyte, so that the rate of addition of the ketone does not exceed the rate of formation of per-mono-sulphate ions formed by hydrolysis. |
