Method for producing vinyl ethers - acetal thermal decomposition

- Sep 21, 2018-

The acetal thermal decomposition decomposition system includes a gas phase system and a liquid phase system. The gas phase cracking method uses a metal as a catalyst to cleave the acetal vapor in a high temperature environment, and deposits a fine metal powder such as silver or gold on a carrier as a catalyst, and cleaves the acetal at 25 ° C to 40 ° C to form an olefin ether. In this process, asbestos boric acid can also be used as a catalyst, and the reaction temperature is between 250 ° C and 500 ° C. The acetal thermal decomposition method can use platinum-asbestos as a catalyst to cleave acetal at 260 ° C to 280 ° C to produce alkenyl ether, or to use a Lewis acid such as palladium or ruthenium as a catalyst to dry boric acid on Al 2 O 3 at 40 Calcination was carried out in a ° C environment to form a catalyst, and the cyclic acetal was cleaved in the range of 180 ° C to 280 ° C to prepare an ether.

In the process of liquid phase decomposition, the acetal is cleaved under appropriate catalyst conditions. This method is relatively easy to control, and its operation equipment is relatively simple. The key reaction conditions are the choice of medium and catalyst, and the reaction of the enol produced by the cracking reaction. The system is separated to avoid recombination with the alcohol produced by the cracking. During the continuous heating process, the cleavage product of the acetal is distilled off, thereby separating the corresponding olefin ether and heating the acetal with a small amount of phosphoric acid as a catalyst. In these conditions, the reactants produce a large amount of black tar, and the yield of the enol is low. In actual work, the treatment of tar-like by-products is complicated. Therefore, the overall application range of the liquid phase method is relatively narrow.