Palladium-containing catalysts

Another of the few selective syntheses of aLkylpyridines is one for a-picoline (2) (76). This is a two-step process (eq. 24) where acrylonitrile is used to monocyanoethylate acetone in the Hquid phase at 180°C and at autogenous pressure, 2 MPa (300 psig). The monoadduct, 5-cyano-2-pentanone, is then passed over a palladium-containing catalyst to reduce, cyclize, and dehydrogenate, in sequence. 

Somewhat unexpectedly, monodemethylation of the esters (159 R=Me) proved impossible using several standard techniques. Deallylation of mono and diallyl ester analogues of (159), and of diallyl and allyl methyl [(1-acetyloxy)alkylJphosphonates was however acheived using palladium-containing catalysts, suggesting a potential wider applicability of the diallyloxy-phosphinyl group in synthesis. 

Allyl chlorides and bromides can be carbonylated to afford the respective unsaturated acids and esters with a variety of catalysts under relatively mild conditions such as 30-50 °C and 1 bar CO (Scheme 5.2). Most prominent are the palladium-containing catalysts and both [PdCl2(TPPMS)2] or [PdCl2(TPPTS)2] and [PdCl2(PPh3)2] were used, dissolved in the aqueous and in the organic phases, respectively [14-16]. 

In this work the preparation of orthophenylenediamine (OPDA) from 4-chloro-2-nitroani1ine was studied on alumina supported palladium catalysts. High OPDA yields were obtained on catalysts containing stabilized ionic palladium. In the preparation of the given palladium containing catalysts anchoring type surface reactions were used. The existence of palladium in ionic form was evidenced by XPS and El R measurements. 

It is another pertinent feature of the catalytic data presented in Figure 1 that the palladium containing catalyst is clearly more active than the platinum containing... 

A synthesis of 5-(alkyn-l-yl)-l,2,4-triazines 77 has been developed, in which, by activation with the palladium-containing catalyst, acetylenes effectively react with 5-chloro- and 5-iodo-l,2,4-triazines 76 (Scheme 46) (84H2245). The synthesis of 5-((o-alkynyl)-l,2,4-triazines 79 has been described using as nucleophile acetylenes 78 featuring a nucleophilic group (e.g., hydroxy or CH-activated group) (Scheme 46). 

The reaction of phosgene with spent platinum-containing or palladium-containing catalysts on aluminium(IIl) oxide, silicon(IV) oxide, or carbon supports at 140-450 C has been used as part of a recovery process [20,231,1864a,1864c], and car exhaust oxidation catalysts can be reactivated by heating in phosgene at 260 "C [1251],... 

Preparation of sodium-[2-(3, 3, 3 - trifluoroprop-l -yl)]-benzenesulfonate The solution is transferred into a hydrogenation flask and activated carbon is added. Under the hydrogen atmosphere the heterogeneous catalyst is formed and the catalytic hydrogenation is carried out. The palladium containing catalyst is separated by filtration and washed with water. 

Generally in the olefin carbonylation stronger reaction conditions have to be applied than in the carbonylation of acetylenes. In the stoichiometric procedure with Ni(CO)4 as catalyst, 150 °C and CO-pressures of about 50 atm are required and in the catalytic procedure conversion can be reali-2ed at 250 °C and a pressure of 200 atm. Palladium-containing catalysts are active already at 80-150 °C [469-471, 1021]. 

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