| abstract |
Aliphatic dicarbonylic compounds containing up to 5 carbon atoms and their hydrates and polymers are prepared by the catalytic oxidation in the vapour phase with excess oxygen of alkylene or polyalkylene glycols in the presence of a hydrogen halide as a repressant. In the example, ethylene glycol vapour and oxygen are passed through a heated copper-silicon-manganese alloy tube containing a silver or copper catalyst. Hydrogen chloride is added intermittently to the gas stream and its effect on the reaction observed by estimating the carbon dioxide content of the exit gas. The catalyst for the reaction may consist of turnings of a copper-silicon-manganese alloy, a copper-alumina catalyst, silver, silver oxide or a molybdenum oxide-titanium oxide catalyst. By this process glycol is obtained from ethylene or polyethylene glycol, pyruvic aldehyde from propylene or polypropylene glycol, diacetyl from 2.3-butylene glycol, malonic dialdehyde from 1.3-propylene glycol, formyl acetone from 1.3-butylene glycol, succinic dialdehyde from 1.4-butylene glycol and laevulinic aldehyde from 1.4-amylene glycol. |