Butanal → 2-Ethylhexanol

According to the present invention, 2-ethyl-1,3-hexane diol is thus prepared from n-butyraldehyde. 0.5-10% by weight, preferably 5-15% by weight, of a neutral phase-transfer catalyst is added to n-butyraldehyde, one such catalyst being, for example, polyethylene glycol (PEG 400), whereafter the mixture is cooled to 0°-20° C. The reaction may also be started from room temperature, but preferably so that the mixture is first cooled. Most preferably the reaction mixture is cooled to a temperature of 5°-15° C., and thereafter an aqueous solution of an alkali metal hydroxide or alkali earth metal hydroxide catalyst is added to the mixture drop by drop at such a rate that the reaction clearly starts, i.e. the temperature of the mixture clearly rises from its original value. The alkali metal hydroxide or alkali earth metal hydroxide is used in a proportion of 0.01-5% by weight, preferably 0.1-1% by weight, to n-butyraldehyde. The adding of the aqueous solution of the catalyst is discontinued when the temperature of the mixture has risen to the range 25°-45° C., preferably, however, to the range 30°-40° C. After the discontinuation of the adding of the catalyst, the mixture is further stirred for 0-5 h, preferably 0.2-3 h, whereafter the organic phase and the aqueous phase are separated from each other. Before the separation of the phases the reaction mixture may be neutralized with a mineral acid or an organic acid. The organic phase is recovered, and it is hydrogenated by catalytic hydrogenation at a temperature of 30°-200° C. and a pressure of 5-100 bar, preferably at a temperature of 60°-140° C. and a pressure of 10-60 bar. The hydrogenation may be carried out by using, for example, a Raney nickel catalyst. After the hydrogenation the product is vacuum distilled. The boiling point of 2-ethyl-1,3-hexane diol is 100° C./6 mbar, and a yield of up to more than 55% is obtained. When the process according to the invention is used, the worst byproduct, 2-ethyl hexanol via 2-ethyl hexenal, is formed at maximum at a rate of 2.6%. The rest of the reaction mixture is unreacted n-butyraldehyde which has become reduced to 1-butanol.

1. temperatureis cooled to 0°-20° C
2. customThe reaction
3. custommay also be started from room temperature
4. temperaturepreferably so that the mixture is first cooled
5. temperatureMost preferably the reaction mixture is cooled to a temperature of 5°-15° C.
6. customthat the reaction
7. additionThe adding of the aqueous solution of the catalyst
8. customhas risen to the range 25°-45° C.
9. customto the range 30°-40° C
10. additionAfter the discontinuation of the adding of the catalyst
11. customthe aqueous phase are separated from each other
12. customBefore the separation of the phases the reaction mixture
13. customThe organic phase is recovered
14. customis hydrogenated by catalytic hydrogenation at a temperature of 30°-200° C.
15. custompreferably at a temperature of 60°-140° C.
16. distillationdistilled
17. customis 100° C.
18. customa yield of up to more than 55% is obtained

ORD record

ord-0cfd7b986b624ab29a4e7a58d06f3558

Source dataset

uspto-grants-1997_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05663452