Abstract: The invention relates to a method for producing optionally substituted aliphatic, aromatic or heteraromatic aldehydes of formula (I), whereby the R represents a C1-C20 Alkyl radical, an aromatic or heteraromatic radical Ar which can optionally be substituted once or on a number of occasions by OH, C1-C6 alkyl, C1-C6 alkoxy, C1-C6 carboxylic acids or ester containing 1-6 C atoms in the ester part, phenyl, halogen, SO3H, NO2, NR1R2 or SR1 whereby R1 and R2 can be independently H, phenyl or C1-C6 alkyl. The invention is characterised by a compound of formula (II) wherein R has the above meaning, a) is diazotized in an acidic medium, at a temperature of between −10 −+100 ° C. by a diazoation reagent and is transformed into the corresponding hydroxy carboxy acid whereby b) is transformed, by means of oxygen, into the appropriate aldehyde of formula (I) in the presence of a metal, the salt thereof, oxide or hydroxide as a catalyst.

Abstract: A method for the production of substituted aromatic aldehydes or ketones and optionally substituted heteroaromatic aldehydes or ketones of formula (I) by reacting a compound of formula (II) in a suitable solvent in the presence of a carbonyl compound of formula (III), optionally in the presence of oxygen at a normal pressure or high temperature and at temperatures of 5-200° C.

Abstract: An electroluminescence color display screen comprising an organic electroluminescence layer disposed between a patterned base electrode layer and a patterned top electrode layer, and further comprising a color conversion layer and a spectrally selective reflector for improving the color efficiency of the color display screen.