4,5,5-Trimethylhexanal → Isononanoic acid

Participants

Reaction Steps

Diisobutene, either prepared by the oligomerization of pure isobutene obtained by redissociation or obtained in the course of workup of a butadiene-free raffinate I, is then converted to a C9 derivative lengthened by one carbon atom. Industrial operation involves the hydroformylation or oxo process in which diisobutene is converted to the corresponding aldehyde with carbon monoxide and hydrogen in the presence of rhodium or cobalt catalysts. Since diisobutene predominantly comprises the octenes 2,4,4-trimethyl-1-pentene and 2,4,4-trimethyl-2-pentene, the hydroformylation reaction gives the C9 aldehyde 3,5,5-trimethylhexanal as the main constituent. Further C9 isomers present in small amounts are 3,4,4- and 3,4,5-trimethylhexanal, and also 2,5,5-trimethylhexanal, 4,5,5-trimethylhexanal and 6,6-dimethylheptanal. Oxidation of this aldehyde mixture gives an industrially available isononanoic acid typically having a content of 3,5,5-trimethylhexanoic acid of about 90% (Ullmanns Encyklopädie der technischen Chemie, 4th Edition, 1975, Verlag Chemie, Volume 9, pages 143-145; EP 1 854 778 A1).

Provenance & Evidence