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Efficient Heterogeneously Palladium-Catalyzed Heck Arylation of Acrolein Diethyl Acetal. Selective Synthesis of Cinnamaldehydes or 3-Arylpropionic Esters.-The heterogeneous complex Pd(NH3)4 on zeolite NaY represents a viable alternative to the homogeneous Pd catalysts in Heck arylation of acrolein diethyl acetal. The reaction provides a wide range of cinnamaldehydes (IV) or arylpropionic acid esters (III), selectively, depending on the use of Cacchi or standard Heck conditions, respectively. Under Heck conditions, the catalyst can be reused for two consecutive runs while no recycling is possible under Cacchi conditions due to increased side product formation. -(NOEL, S.; LUO, C.; PINEL, C.; DJAKOVITCH*, L.; Adv. Synth. Catal. 349 (2007) 7, 1128-1140; Inst. Rech. Catal. Environ., CNRS, Univ. Claude Bernard Lyon, F-69626 Villeurbanne, Fr.; Eng.) -Mischke 36-037

Industrial Kraft black liquor from maritime pine was oxidized in aqueous, alkaline medium, under air, at 150C, with or without CuO/TiO2 catalyst. The oxidation products were analyzed by HPLC, elemental analysis, SEC, FTIR, NMR. The results showed the depolymerisation of lignin, the formation of phenolic compounds in low yields, with vanillin being the major phenolic compound, and the formation of aliphatic compounds in higher yields, with formic, succinic and tartronic acids being the major identified aliphatic compounds. The presence of catalyst favoured the formation of phenolic and aliphatic compounds. Replacing Kraft black liquor by pure Kraft lignin as a starting material did not enhance the performances of catalytic oxidation, showing that lignin purification may not be necessary in our conditions. Switching from a batch reactor to a fixed bed reactor, working under similar conditons, did not increase the yields in oxidation products but increased the productivity. This work shows the potential of Kraft black liquor to produce a large panel of compounds, including phenolics, aliphatic acids and oxidized lignin, all being valuable in chemical industry.

Influence of the Catalytic Conditions on the Selectivity of the Pd-Catalyzed Heck Arylation of Acrolein Derivatives. -The Heck arylation of a variety of aryl bromides with acrolein is readily achieved in the presence of the Hermann-Beller palladacycle. When the diethylacetal of acrolein is used, the choice of the catalyst affects the selectivity of the reaction dramatically. -(NOEL, S.; DJAKOVITCH*, L.; PINEL, C.; Tetrahedron Lett. 47 (2006) 23, 3839-3842; Inst. Rech. Catal., CNRS, Univ. Claude Bernard Lyon, F-69626 Villeurbanne, Fr.; Eng.) -Mais 37-048