Process for the preparation of formylvaleric acid and adipic acid
The invention relates to a process for the production of 5-formylvaleric acid and adipic acid or esters thereof from an isomeric mixture of pentenoic acid or esters thereof said mixture comprising at least 4-pentenoic acid or esters thereof, and further comprising 3-pentenoic acid and/or 2-pentenoic acid or esters thereof. The process allows for efficient production of two different intermediates for producing polyamide using a single process, with good selectivity, little waste, in an economically efficient fashion. The process is very suitable to use an isomeric pentenoic acid mixture obtained from valerolactone, and can be used to produce renewable polyamide intermediates using a single process.
1. Process for the production of 5-formylvaleric acid and adipic acid or esters thereof from an isomeric mixture of pentenoic acid or esters thereof said mixture comprising at least 4-pentenoic acid or esters thereof, and further comprising 3-pentenoic acid and/or 2-pentenoic acid or esters thereof, the process comprising:
(a) subjecting the isomeric mixture of pentenoic acid to a hydroformylation reaction comprising a hydroformylation catalyst which is non-isomerizing towards the pentenoic acid or esters thereof to obtain a mixture comprising 5-formylvaleric acid or esters thereof and further comprising 3-pentenoic acid and/or 2-pentenoic acid, or esters thereof;
(b) separating the 3-pentenoic acid and/or 2-pentenoic acid, or esters thereof from the 5-formylvaleric acid or esters thereof;
(c) subjecting the separated pentenoic acids or esters thereof to a carbonylation reaction comprising a isomerizing carbonylation catalyst to obtain adipic acid or esters thereof;
(d) optionally isolating the adipic acid or ester thereof; and
(e) optionally isolating the separated 5-formylvaleric acid or esters thereof.
2. Process according to claim 1 wherein the amount of 4-pentenoic acid or esters thereof in the isomeric mixture is between 5 and 95 mol % relative to the total amount of pentenoic acid or esters thereof.
3. Process according to claim 1 wherein the isomeric mixture of pentenoic acid or esters is obtained from valerolactone by subjecting said valerolactone to an acid- or base-catalysed ring opening reaction.
4. Process according to claim 3 wherein the valerolactone is obtained from levulinic acid in a hydrogenation reaction.
5. Process according to claim 1 wherein the 5-formylvaleric acid or ester thereof is used to produce caprolactam by converting said 5-formylvaleric acid or ester thereof into caprolactam in a reductive amination reaction, followed by ring-closing.
6. Process according to claim 1 wherein hydroformylation catalyst system comprises rhodium.
7. Process according to claim 1 wherein the hydroformylation catalyst system comprises a monodentate or bidentate phosphine ligand.
8. Process according to claim 7 wherein the monodentate ligand comprises tris-sulfonated triphenylphosphine.
9. Process according to claim 1 wherein the hydroformylation reaction is carried out in an organic-aqueous two phase reaction medium.
10. Process according to claim 9 wherein the aqueous phase is separated and recycled back to the hydroformylation reaction.
11. Process according to claim 1 wherein the carbonylation reaction comprises a source of palladium; a bidentate phosphine ligand of formula I;
R1R2P-R3-R-R4-PR5R6 (I)
wherein P represents a phosphorus atom; R1, R2, R5 and R6 can independently represent the same or different optionally substituted organic groups containing a tertiary carbon atom through which the group is linked to the phosphorus atom; R3 and R4 independently represent optionally substituted lower alkylene groups and R represents an optionally substituted aromatic group; a source of anions derived from an acid with a pKa<3; carbon monoxide; and an OH comprising compound.