BATCH AND CONTINUOUS PROCESS FOR ISOLATION OF DIKETENE FROM KETENE DIMERIZATION PRODUCT Russian patent published in 2003 - IPC

FIELD: industrial organic synthesis. SUBSTANCE: diketene is produced by dimerization of ketene obtained via pyrolysis of acetone. Isolation of high-purity diketene is effected from solutions containing closely boiling admixtures: acetic anhydride and acetic acid. Distillation, first atmospheric and then under vacuum, is performed consecutively. Vacuum distillation is carried out on heat- and mass-exchange apparatus provided with heat- and mass-exchange bags made in the form of Z- shaped corrugations from metal sheet or gaze and also with special devices for uniform distribution of phlegm throughout the trans-section of apparatus, specific surface of bags being 250 to 750 sq. m/cu.m ensured by corresponding height of corrugations and their inclination to vertical. In this case, pressure gradient 10 to 80 mm Hg is created between the top and the bottom of apparatus, residual pressure in the top of apparatus being 60 to 250 mm Hg and temperature difference on the 7th (from the bottom) theoretic plate and the top of apparatus ranging between 10 and 40 C. Desired product is withdrawn from the top of apparatus in a batch-mode process. When continuous process is carried out, still residue from the first vacuum apparatus is routed to feed second heat-exchange apparatus and desired diketene fraction is received from the top. EFFECT: increased yield and improved quality of desired product. 11 ex