GB1458097A - Process for the production of alkene-1,5-diols - Google Patents

Abstract

1458097 Alkene-1,5-diols CHEVRON RESEARCH CO 11 July 1974 [16 July 1973 8 April 1974] 30837/74 Heading C2C Alkene-1,5-diols are prepared by mixing 3- methyl-3-buten-1-ol with water and formaldehyde and reacting the mixture in the presence of added isobutene at elevated temperature and pressure, the temperature being below the critical temperature of the said mixture, and the pressure sufficiently high to maintain at least part of the reaction mixture in the liquid phase. The diols obtained are 3-methylene- 1,5 - pentanediol and the two 3 - methyl- 2 - pentene - 1,5 - diol isomers. The temperature is preferably 150-300‹ C. and the pH of the mixture between 4À0 and 7À0, maintained by a buffer comprising a weak acid and the salt of a weak acid; pressure is conveniently 100-5000 p.s.i.g. The formaldehyde is conveniently added with the water as an aqueous solution. It is preferred that sufficient isobutene and formaldehyde are added so that production of alkene-1,5-diols takes place with no net consumption of 3-methyl-3-buten-1-ol, the overall result being the production of the alkene diols from isobutene and formaldehyde in a single stage. The product may be separated into two portions, one containing the diols and the other comprising formaldehyde, water, isobutene and 3-methyl-3-buten-1-ol, the second portion being recycled to the reaction, optionally after partial dehydration, e.g. by salting out water with concentrated aqueous potassium carbonate. Alternatively the product may be separated into isobutene (recycled), water, 3-methyl-3-buten-1-ol (recycled) and alkene-1,5-diols. A solvent, e.g. a lower alcohol, may be present.