# US 9,517,995 B2 · Method for producing isomeric hexanoic acids from the subsidiary flows arising during the production of pentanals > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,517,995 B2 - Document ID: US9517995B2 - Status: Granted - Kind: B2 - Application number: 15/033,709 - Filed: 2014-11-14 - Published: 2016-09-29 - Granted: 2016-12-13 - Earliest claimed: 2013-12-05 - Assignees: Oxea GmbH - Applicants: Oxea GmbH - Inventors: Jens Theuerkauf; Heinz Strutz - Web page: https://patentgrep.com/patent/US9517995B2 ## CPC - C07C 51/235: of —CHO groups or primary alcohol groups - C07C 45/50: by oxo-reactions - C07C 45/62: by hydrogenation of carbon-to-carbon double or triple bonds - C07C 45/66: by dehydration - C07C 45/75: Reactions with formaldehyde - C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS ## Abstract A process for preparing isomeric hexanoic acids comprising 2-methylpentanoic acid from the secondary streams obtained in the preparation of pentanals, characterized in that a) a mixture comprising linear butenes is reacted to give a pentanal mixture; b) the mixture obtained in step a) is separated into a stream enriched with 2-methylbutanal and 3-methyl-butanal, and a stream enriched with n-pentanal; c) the stream enriched with 2-methylbutanal and 3-methylbutanal of step b) is reacted with formaldehyde; d) the reaction mixture obtained after step c) is selectively reacted to give a mixture comprising 2-methylbutanal and isomeric hexanals; e) the reaction mixture is separated into a stream enriched with 2-methylbutanal and a stream enriched with a mixture of isomeric hexanals; and f) the mixture of isomeric hexanals obtained in step e) is oxidized to a mixture of isomeric hexanoic acids comprising 2-methylpentanoic acid. ## Claims ### Claim 1 A process for preparing isomeric hexanoic acids comprising 2-methylpentanoic acid from the secondary streams obtained in the preparation of pentanals, characterized in that a) a mixture comprising linear butenes is reacted in the presence of transition metal compounds of group VIII of the Periodic Table of the Elements with carbon monoxide and hydrogen at elevated temperature and elevated pressure to give a pentanal mixture; b) the mixture obtained in step a) is separated into a stream enriched with 2-methylbutanal and 3-methyl-butanal, and a stream enriched with n-pentanal; c) the stream enriched with 2-methylbutanal and 3-methylbutanal of step b) is reacted with formaldehyde; d) the reaction mixture obtained after step c) is selectively reacted in the presence of a hydrogenation catalyst with hydrogen at elevated temperature and elevated pressure to give a mixture comprising 2-methylbutanal and isomeric hexanals; e) the reaction mixture obtained in step d) is separated into a stream enriched with 2-methylbutanal and a stream enriched with a mixture of isomeric hexanals; and f) the mixture of isomeric hexanals obtained in step e) is oxidized to a mixture of isomeric hexanoic acids comprising 2-methylpentanoic acid. ### Claim 2 A process for preparing isomeric hexanoic acids comprising 2-methylpentanoic acid from the secondary streams obtained in the preparation of pentanals, characterized in that a) a mixture comprising linear butenes is reacted in the presence of transition metal compounds of group VIII of the Periodic Table of the Elements with carbon monoxide and hydrogen at elevated temperature and elevated pressure to give a pentanal mixture; b) the mixture obtained in step a) is separated into a stream enriched with 2-methylbutanal and 3-methyl-butanal, and a stream enriched with n-pentanal; c) the stream enriched with 2-methylbutanal and 3-methylbutanal of step b) is reacted with formaldehyde; d) a stream enriched with 2-methylbutanal and a stream depleted of 2-methylbutanal are recovered from the reaction mixture obtained after step c); e) the stream depleted of 2-methylbutanal obtained after step d) is selectively reacted in the presence of a hydrogenation catalyst with hydrogen at elevated temperature and elevated pressure to give a mixture comprising isomeric hexanals; and f) the reaction mixture obtained in step e) is oxidized and isomeric hexanoic acids are removed by distillation. ### Claim 3 A process for preparing isomeric hexanoic acids comprising 2-methylpentanoic acid from the secondary streams obtained in the preparation of pentanals, characterized in that a) a mixture comprising linear butenes is reacted in the presence of transition metal compounds of group VIII of the Periodic Table of the Elements with carbon monoxide and hydrogen at elevated temperature and elevated pressure to give a pentanal mixture; b) the mixture obtained in step a) is separated into a stream enriched with 2-methylbutanal and 3-methyl-butanal, and a stream enriched with n-pentanal; c) the stream enriched with 2-methylbutanal and 3-methylbutanal of step b) is reacted with formaldehyde; d) the reaction mixture obtained after step c) is selectively reacted in the presence of a hydrogenation catalyst with hydrogen at elevated temperature and elevated pressure to give a mixture comprising 2-methylbutanal and isomeric hexanals; and e) the reaction mixture obtained in step d) is oxidized and then 2-methylbutyric acid and a mixture of isomeric hexanoic acids comprising 2-methylpentanoic acid are removed by distillation. ### Claim 4 (depends on 1) The process as claimed in claim 1, characterized in that the reaction with formaldehyde in step c) is effected in the presence of a secondary amine and a mono-, di- or polycarboxylic acid. ### Claim 5 (depends on 1) The process as claimed in claim 1, characterized in that distillation is effected during the reaction with formaldehyde in step c). ### Claim 6 (depends on 1) The process as claimed in claim 1, characterized in that the secondary amine used is an alkylamine of the formula R1—NH—R2 where R1 and R2 are the same or different and are each alkyl radicals having 1 to 12 carbon atoms. ### Claim 7 (depends on 1) The process as claimed in claim 1, characterized in that a monocarboxylic acid having 1 to 10 carbon atoms or a di- or polycarboxylic acid having 2 to 10 carbon atoms is used. ### Claim 8 (depends on 1) The process as claimed in claim 1, characterized in that the oxidation is effected in the presence of alkali metal or alkaline earth metal carboxylates. ### Claim 9 (depends on 8) The process as claimed in claim 8, characterized in that the alkali metal or alkaline earth metal carboxylates used are lithium carboxylate, potassium carboxylate, sodium carboxylate, calcium carboxylate or barium carboxylate. ### Claim 10 (depends on 1) The process as claimed in claim 1, characterized in that the oxidation is conducted in the liquid phase. ### Claim 11 (depends on 1) The process as claimed in claim 1, characterized in that the oxidizing agent used is oxygen or oxygen-containing gases. ### Claim 12 (depends on 1) The process as claimed in claim 1, characterized in that the reaction with formaldehyde is conducted continuously in a flow tube. ### Claim 13 (depends on 2) The process as claimed in claim 2, characterized in that the reaction with formaldehyde in step c) is effected in the presence of a secondary amine and a mono-, di- or polycarboxylic acid. ### Claim 14 (depends on 3) The process as claimed in claim 3, characterized in that the reaction with formaldehyde in step c) is effected in the presence of a secondary amine and a mono-, di- or polycarboxylic acid. ### Claim 15 (depends on 2) The process as claimed in claim 2, characterized in that distillation is effected during the reaction with formaldehyde in step c). ### Claim 16 (depends on 3) The process as claimed in claim 3, characterized in that distillation is effected during the reaction with formaldehyde in step c). ### Claim 17 (depends on 4) The process as claimed in claim 4, characterized in that distillation is effected during the reaction with formaldehyde in step c). ### Claim 18 (depends on 2) The process as claimed in claim 2, characterized in that the secondary amine used is an alkylamine of the formula R1—NH—R2 where R1 and R2 are the same or different and are each alkyl radicals having 1 to 12 carbon atoms. ### Claim 19 (depends on 3) The process as claimed in claim 3, characterized in that the secondary amine used is an alkylamine of the formula R1—NH—R2 where R1 and R2 are the same or different and are each alkyl radicals having 1 to 12 carbon atoms. ### Claim 20 (depends on 4) The process as claimed in claim 4, characterized in that the secondary amine used is an alkylamine of the formula R1—NH—R2 where R1 and R2 are the same or different and are each alkyl radicals having 3 to 5 carbon atoms.