Preparation of linear long chain dialdehydes by hydroformylation of linearalpha,omega-dienes or omega-vinylaldehyde acetals

Linear long chain dialdehydes, a class of valuable intermediates for a wide variety of commercially important products and of interesting cross-linkin g agents for protein and polysaccharides, can be conveniently prepared by h ydroformylation of alpha,omega -diolefins and protected aldehydes having a terminal olefinic double bond. Thus, 1,5-hexadiene and 1,6-heptadiene were converted in a single oxo-process step into the corresponding linear dialde hydes in very high yields (80-98%), using RhH(CO)(PPh3)(3)/Xantphos (1:3) a s the catalytic system at 40-60 degreesC and 20 atm (CO: H-2 = 1). If more stable monoprotected dialdehydes are needed, they can be obtained i n a > 90% yield by hydroformylation of ethylene acetals of omega -vinylalde hydes, like 2-(9-decenyl)- and 2-(10-undecenyl)-1,3-dioxolane, catalysed by the above Xantphosrhodium complex under analogous reaction conditions. Thi s catalytic system showed to be superior to platinum complexes such as PtHC I(PPh3)(3)/(SnCl2H2O)-H-., which require more drastic reaction conditions ( 100atm and 100 degreesC)to ensure yields of linear protected aldehydes rang ing from 65 to 86%. (C) 2001 Elsevier Science B.V. All rights reserved.