Preparation of aldehydes only from esters

Aliphatic or aromatic ESTERS can be reduced specifically to ALDEHYDES using diisobutylaluminium hydride, DIBAl-H (also written AlH(i-Bu)2): R-CO-O-R' with AlH(i-Bu)2, then H3O+ on workup, gives R-CHO + R'-OH. The reaction is deliberately carried out at a low temperature -- around 195 K -- specifically to stop the newly-formed aldehyde from being reduced any further, all the way down to …