FIELD: chemical technology, alkenes. SUBSTANCE: process is carried out by splitting by-side products of 4,4-dimethyl-1,3-dioxane synthesis on catalyst at specific surface 0.2-1.0 m2/g in the presence of steam, preferably at 200-480 C. Catalyst: solid contact and oxide catalyst of the following composition, wt.-%: aluminium oxide 5-30; iron oxide 0.1-5.0; magnesium oxide 0.1-5.0; calcium oxide 0.1-5.0; potassium oxide 0.1-3.0; titanium dioxide 0.1-3.0, and silicon dioxide - the rest at mass ratio of solid contact : oxide catalyst = (0.05-0.3):1. Solid contact is placed over oxide catalyst. Method ensures to increase the total yield of products by 8.7 wt.-%, decrease methanol yield by 1.7 wt.-%, decrease gas evolving by 1.5 wt.-%, increase conversion of high-boiling by-side products and heavy residue by 7.5% and 3.7%, respectively. Method can be used in petroleum chemistry. EFFECT: improved method of synthesis, enhanced effectiveness and yield of products. 2 cl, 1 tbl
