METHOD OF PRODUCTION OF METHYLMETHACRYLATE Russian patent published in 2003 - IPC

FIELD: organic chemistry, chemical technology. SUBSTANCE: invention relates to the improved method for preparing methylmethacrylate involving the following steps: (i) interaction of propionic acid or its ester with formaldehyde or its precursor in the condensation reaction to form flow of gaseous products comprising methylmethacrylate, residual reagents, methanol and by-side substances; (ii) treatment of at least one portion of flow of gaseous substances to form flow of liquid products comprising practically all methylmethacrylate and at least one by-side impurity melting at the melting point above the melting point of pure methylmethacrylate; and performing at least one procedure of batch crystallization over the flow of liquid substances that involves steps: (iii) cooling indicated flow of liquid substances to temperature between about 45 C and about 95 C so that indicated flow of liquid products forms crystals of solid methylmethacrylate and mother liquor being indicated crystals comprise the higher part of methylmethacrylate content than indicated flow of liquid products or mother liquor; (iv) separation of indicated solid methylmethacrylate crystals from indicated mother liquor and (v) melting indicated crystals to form liquid methylmethacrylate that comprises flow of liquid products. Invention relates also to method for isolation of methylmethacrylate from liquid mixture containing methylmethacrylate and up to 20% of liquid impurities with the melting point above the melting point of pure methylmethacrylate. Method allows to obtain practically pure methymethacrylate from the complex flow of compounds containing some impurities with the melting points both above and lower than for pure methymethacrylate. EFFECT: improved preparing method. 5 cl, 3 tbl, 5 ex