GB1173242A - Recovery of HI in Manufacture of Unsaturated Organic Compounds - Google Patents

Abstract

1,173,242. Dehydrogenation process. EASTMAN KODAK CO. 15 May, 1967 [16 May, 1966], No. 22520/67. Addition to 1,115,771. Heading C2C. [Also in Division C1] In a process for producing ethylenically unsaturated compounds by heating an organic compound, which contains 2 adjacent carbon atoms linked by a single bond and each having at least one hydrogen atom attached thereto, at 450-700‹ C. in the presence of oxygen and 0À5-10%, based on weight of organic compound, of aqueous hydrogen iodide hydrate solution containing 2-60% by wt. HI, quenching the effluent from the reaction zone with previously condensed effluent and separating the ethylenically unsaturated product, free from iodine, from the condensed effluent, the aqueous residue is distilled to remove water and organic compounds boiling below 100‹ C. and then distilling the residue to obtain overhead a mixture of hydrogen iodide and water which is raised in the dehydrogenation stage. The unsaturated product may be separated from the condensed effluent by decantation. The first distillation of the aqueous residue removes organic compounds, such as alcohol and acetone, and water overhead leaving a residue which is more concentrated in HI. Distillation of this residue may yield an azeotrope of water and HI containing 57% HI which is preferably diluted to about 20% before recycling. The process is illustrated by reference to drawings (not shown) and the preparation of methyl methacrylate from methyl isobutyrate. Other specified unsaturated products are methyl 2-methylpentenoate from methyl 2-methyl-pentanoate, methyl C 8 esters from methyl 2-ethyl-hexanoate and methacrylic acid from isobutyric acid.