SU139656A1 - The method of electrochemical synthesis of sebacic acid - Google Patents

Description

A known method for the synthesis of sebacic acid, based on the electrochemical condensation of sodium monomethyladinate in electrolyzers with platinum anodes. In the implementation of this method, the consumption of platinum for the manufacture of even a very thin electrode with a surface of 1 dm (from platinum foil 0.05 mm thick is 10.7 g

In addition, with such a small electrode thickness, for current to be evenly distributed across the electrode surface, current is required from all sides around the plate perimeter, which requires additionally significant amounts of platinum and special measures are taken to protect the common non-precious metal from destruction. Significant difficulties also arise; e while ensuring reliable contact of the leads with the main plate.

In contrast to the known, the proposed method for the electrochemical synthesis of sebacic acid involves the use of titanium anodes electrochemically coated with a layer of platinum with a thickness of 0.003 mm. The consumption of platinum for the manufacture of such an anode with a surface of 1 dAi is 1.3 g, i.e., more than 8 times lower than in the manufacture of a flat platinum anode. In addition, the peculiarity of the proposed anode is that electrolysis takes place only in areas covered with platinum, while titanium covered with a passive film does not conduct current and does not deteriorate during electrolysis when used as an anode, as a result of which platinum or to protect titanium from damage on non-platinum-coated sites. At the same time, the problem of the reliability of the contacts of the conductors with the electrode is replicated, and it creates the possibility of working with specific current loads of up to 40 a1 dm versus 6.7 a1 dm when using solid platinum anodes.

139656-2 Example 1. A 345 ml methanolic solution containing 350 g of liter, mymethyl adipate and 18 g of crystalline soda are poured into the electrolysis cell, which is a glass cylindrical vessel equipped with a coil cooler. Electrodes, skreilenny in one package, have the form of rectangular plates. The middle titanium plate, which serves as the anode, is galvanically coated with a layer of platinum 0.003 mm thick. The working surface of the plate is 0.2 djH. Perforated cathode plates are made of stainless steel and placed on both sides of the anode plate at a distance of 5 mm. To prevent short circuits, fluoroplastic gaskets are placed between the plates. Electrolysis is carried out at an anodic current density of 19 a / dm and an electrolyte temperature of 64 °.

After completion of the electrolysis, the electrolyte is boiled with an excess of sodium alkali for 6-7 hours, after which the spirg is distilled off and the solution is acidified with 20% sulfuric acid. The precipitated sebacic acid is extracted with sulfuric ether and the ether extract is extracted with anhydrous sodium sulfate. After distilling off the sulfuric ester, the resulting sebacic acid is dried again. The yield of sebaceous acid in substance is 90-95% of the theoretical, the current efficiency is 63-68%. After recrystallization of sebacic acid, the material yield, based on the recrystallized product, is 85-86%.

Example 2. In the electrolyzer described in example 1, electrolysis of a methanol solution containing 350 g of monomethyl adipate and 68 g of crystalline soda is carried out in a liter. At an anode current density of 40 a / dm and an electrolyte temperature of 64 °, the substance yield is 90%, the current output is 62-63%.

Subject invention

The method of electrochemical synthesis of sebacic acid from sodium monomethyl adipate, characterized in that, in order to improve the contacts of the current leads with the electrode and save platinum, titanium coated with a layer of platinum is used as the anode.