Method for producing isononanoic acid esters, starting from 2-ethyl hexanol
A Process for preparing carboxylic esters of a mixture of structurally branched C9 monocarboxylic acids proceeding from 2-ethylhexanol is characterized in that (a) 2-ethylhexanol is dehydrated to an octene mixture in the presence of a catalyst; (b) the octene mixture obtained in step a) is reacted in the presence of a transition metal compound of group VIII of the periodic table of the elements with carbon monoxide and hydrogen to give a mixture of isomeric isononanals; (c) the mixture of isomeric isononanals obtained in step b) is oxidized to a mixture of structurally branched C9 monocarboxylic acids; and (d) the mixture of structurally branched C9 monocarboxylic acids obtained in step c) is reacted with alcohols to give carboxylic esters.
1. A process for preparing carboxylic esters of a mixture of structurally branched C9 monocarboxylic acids proceeding from 2-ethylhexanol, wherein
(a) 2-ethylhexanol is dehydrated to an octene mixture in the presence of a catalyst;
(b) the octene mixture obtained in step a) is reacted in the presence of a transition metal compound of group VIII of the periodic table of the elements with carbon monoxide and hydrogen to give a mixture of isomeric isononanals;
(c) the mixture of isomeric isononanals obtained in step b) is oxidized to a mixture of structurally branched C9 monocarboxylic acids; and
(d) the mixture of structurally branched C9 monocarboxylic acids obtained in step c) is reacted with alcohols to give carboxylic esters.
2. The process according to claim 1 , wherein the catalyst used in step a) is alumina, nickel precipitated on alumina, or phosphoric acid precipitated on silica or alumina.
3. The process according to claim 1 , wherein 2-ethylhexanol is dehydrated in the gas phase in step a).
4. The process according to claim 1 , wherein the transition metal compound of group VIII of the periodic table of the elements used in step b) is a cobalt or rhodium compound.
5. The process according to claim 1 , wherein the reaction in step b) is performed in the absence of complex-forming organophosphorous compounds.
6. The process according to claim 1 , wherein the mixture of isomeric isononanals obtained in step b) is distilled.
7. The process according to claim 1 , wherein the oxidation in step c) is effected in the presence of alkali metal or alkaline earth metal carboxylates.
8. The process according to claim 7 , wherein the alkali metal or alkaline earth metal carboxylate used is lithium isononanoate, potassium isononanoate, sodium isononanoate, calcium isononanoate or barium isononanoate.
9. The process according to claim 1 , wherein the mixture of isomeric isononanals is oxidized in the liquid phase in step c).
10. The process according to claim 1 , wherein the mixture of isomeric isononanals is oxidized in step c) with oxygen or oxygen-containing gases provided to the mixture of structurally branched C9 monocarboxylic acids.
11. The process according to claim 1 , wherein the reaction in step d) is performed in the presence of an adsorbent.
12. The process according to claim 1 , wherein the reaction in step d) is performed in the presence of a catalyst.
13. The process according to claim 1 , wherein the alcohols converted in step d) are of the general formula (I)
R(OH) n (I)
in which R is an aliphatic, cycloaliphatic or aromatic hydrocarbyl radical having 1 to 20 carbon atoms, and n is an integer from 1 to 8.
14. The process according to claim 1 , wherein the alcohols converted in step d) are of the general formula (II)
H—(—O—[—CR 1 R 2 —] m —) o —OH (II)
in which R 1 and R 2 are each independently hydrogen or an alkyl radical having 1 to 5 carbon atoms, or a hydroxyalkyl radical having 1 to 5 carbon atoms, m is a number from 1 to 10, and o is an integer from 2 to 15.
15. The process according to claim 1 , wherein the alcohol used in step d) is glycidyl alcohol.
16. The process according to claim 2 , wherein 2-ethylhexanol is dehydrated in the gas phase in step a).
17. The process according to claim 2 , wherein the transition metal compound of group VIII of the periodic table of the elements used in step b) is a cobalt or rhodium compound.