Carbon monoxide addition

C-19 dicarboxyhc acid can be made from oleic acid or derivatives and carbon monoxide by hydroformylation, hydrocarboxylation, or carbonylation. In hydroformylation, ie, the Oxo reaction or Roelen reaction, the catalyst is usually cobalt carbonyl or a rhodium complex (see Oxo process). When using a cobalt catalyst a mixture of isomeric C-19 compounds results due to isomerization of the double bond prior to carbon monoxide addition (80). 

Labelling studies with 13C-enriched acetic acid, where 13C NMR data are consistent with carbon monoxide addition to the carbonyl carbon of the acid substrate. 

The behavior of Rh(I) dpm-bridged complexes offers an interesting counterpoint to the Pd(I) based chemistry. For example carbon monoxide addition to the A-frame Rh2(dpm)2(y-Cl)(C0)2 (15, 25,26) and to the face-to-face dimer Rh2(dpm)2(C0)2Cl2 (27) results in shortening the Rh-Rh separations as shown in reactions (12) and (13). Structural characterization of the common product... 

Uranium complexes have also shown imprecedented reactivity with carbon monoxide. Addition of carbon monoxide to [(COT)(Cp )U(THF)j [122] produced a dimeric 0303 debate uranium complex, [ ( j -Cp )( j -COT)U 2... 

Elliott 7) has reported some experiments using wood flour, lignin, and cellulose without any addition of CO. At 350 C final temperature for 1 hr, with 18% substrate slurry, the oil yields were 39, 23, and 30% respectively. The result with cellulose is in agreement with our data. The effect of carbon monoxide addition to an aqueous system with a 30% cellulose slurry was to increase oil yield by only 3-4% in our experiments, up to 500 psig initial CO pressure. This is also in agreement with Elliott s data. The CO-enhancement effect on oil yield is thus barely noticeable with cellulose at CO pressures below 500 psig. 

The reaction of stable N-heterocyclic carbenes (NHCs) with carbon monoxide and the carbonylation of diazo compounds also provide routes to ketene formation. Ketene formation by carbon monoxide addition to a stable carbene (with 55% conversion) has been confirmed by the characteristic IR absorption, and the ketene has been isolated as a purple solid at low temperature with the structure determined by X-ray crystallography (Scheme 7.42). 

The present section is limited to Pd(II)-catalyzed reactions initiated by nucleophilic attack of RO— (R = H, alkyl, aryl) or R2N— (R = H, H and alkyl, aryl) groups on carbon monoxide or carbon dioxide followed by attack of the resulting hydroxy-, alkoxy-, aryloxy-, or amino-carbonyl or carboxyl group on double or triple bonds, the process being terminated by H-addition or elimination or continued by a new carbon monoxide addition, followed by other elementary acts leading to termination. 

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