1-Pentene, carbonylation catalyst

Acyl halides are intermediates of the carbonylations of alkenes and organic-halides. Decarbonylation of acyl halides as a reversible process of the carbo-nylation is possible with Pd catalyst. The decarbonylation of aliphatic acid chlorides proceeds with Pd(0) catalyst, such as Pd on carbon or PdC, at around 200 °C[109,753]. The product is a mixture of isomeric internal alkenes. For example, when decanoyl chloride is heated with PdCF at 200 C in a distillation flask, rapid evolution of CO and HCl stops after I h, during which time a mixture of nonene isomers was distilled off in a high yield. The decarbonylation of phenylpropionyl chloride (883) affords styrene (53%). In addition, l,5-diphenyl-l-penten-3-one (884) is obtained as a byproduct (10%). formed by the insertion of styrene into the acyl chloride. Formation of the latter supports the formation of acylpalladium species as an intermediate of the decarbonylation. Decarbonylation of the benzoyl chloride 885 can be carried out in good yields at 360 with Pd on carbon as a catalyst, yielding the aryl chloride 886[754]. 

The introduction of alkyl phosphine complexes of cobalt carbonyl as hydroformylation catalysts was reported to have a significant effect on product composition (50, 51). Slaugh and Mullineaux (52) reported that hexanol with a 91% linear distribution was formed by the hydroformylation of 1-pentene at 150°C, 500 psi, H2/CO 2.0, catalyst [Co2(CO)8 + 2(n-C4H9)3P]. Under the same conditions except at a temperature of 190°C, the n-hexanol was 84% of the hexyl alcohol produced. 

S)-(-)-CITRONELLOL from geraniol. An asymmetrically catalyzed Diels-Alder reaction is used to prepare (1 R)-1,3,4-TRIMETHYL-3-C YCLOHEXENE-1 -CARBOXALDEHYDE with an (acyloxy)borane complex derived from L-(+)-tartaric acid as the catalyst. A high-yield procedure for the rearrangement of epoxides to carbonyl compounds catalyzed by METHYLALUMINUM BIS(4-BROMO-2,6-DI-tert-BUTYLPHENOXIDE) is demonstrated with a preparation of DIPHENYL-ACETALDEHYDE from stilbene oxide. A palladium/copper catalyst system is used to prepare (Z)-2-BROMO-5-(TRIMETHYLSILYL)-2-PENTEN-4-YNOIC ACID ETHYL ESTER. The coupling of vinyl and aryl halides with acetylenes is a powerful carbon-carbon bond-forming reaction, particularly valuable for the construction of such enyne systems. 

Dehydration of aldols to a,/3-unsaturated carbonyl compounds usually is achieved best with acidic catalysts. An example is the dehydration of the aldol from 2-propanone to give 4-methyl-3-penten-2-one ... 

For cis-chelate complexes of rhodium and bisphosphines as catalysts, indeed relatively low ratios of n/i aldehyde products were reported (12, 13). Using a 1 1 mixture of H CO at atmospheric pressure, Sanger reported n/i ratios ranging from 3 to 4 for propylene hydroformylation (12). However, his catalyst systems were produced by adding less than 2 mol of bisphosphine per mole tris(triphenyl-phosphine)rhodium carbonyl hydride. When an excess of the chelating bisphosphines was used by Pittman and Hirao (13), low n/i ratios close to 1 were produced from 1-pentene using a mixture of H2/CO at 100-800 psi between 60° and 120°C. 

The scheme reduces to its most simple form when carbon monoxide is the only ligand present in the system, because equilibria of mixed ligand/carbon monoxide complexes do not occur. The kinetics of the hydroformylation reaction using hydrido rhodium carbonyl as the catalyst was studied by Marko [29]. For 1-pentene the rate expression found is ... 

The Fe3(CO)i2-catalyzed isomerization of 3-ethyl-l-pentene-3di gives 3-ethyl-2-pentene in which the deuterim label is randomly scrambled among the three methyl groups without loss of deuterium . The recovered 1-olefin also shows rapid random scrambling. These experiments demonstrate the intermediacy of w-allyl iron carbonyl hydrides and indicate Aat multiple addition-eliminations proceed before decomplexation of the catalyst occurs as... 

Steric factors in the olefin substrate can severely retard carbonylation with the platinum catalysts. For example olefins such as 2-decene, cyclohexene or 2,4,4-trimethyl-1-pentene are unreactive. 

Unsaturated aldehydes and ketones can be selectively hydrogenated to the corresponding saturated carbonyl however, it is difficult to reduce the ethylenic group without also attacking the carbonyl group, although such a reduction may be achieved for certain compounds such as mesityl oxide (2-methyl-pentene-2-one-4) using a platinum catalyst at room temperature. 

Using this scheme, Pittman was able to use RhCl3/(CH3)3N as a catalyst for carbonylation of 1-pentene as shown below (J3). Significant amounts of alcohol were also found in the product mixtures. 

Examples of sohd-bound Pd-catalyzed carbonylation of aryl and alkenyl halide, allyl alcohol, and derivatives are abundant in the literature. Polyketones have been obtained via carbonylation of ethylene and carbon monoxide catalyzed by palladium complexes of polysiloxane-bound phosphinet t or Pd(dppp) absorbed on alumina.f f Similar processes can also be carried out by catalyst formed simply by absorbing Pd(02CNEt2)2(NHEt2)2 onto silica geL Polyphosphine-bound palladium has been used to prepare ethyl hexanoate from 1-pentene, CO, and ethanol. Similar esterification of styrene has been achieved using a bimetallic system involving palladium and nickel immobilized on poly(Af-vinyl-2-pyrrolidone).f ... 

A variety of coordinatively unsaturated metal carbonyl species are known to be potent homogeneous catalysts. Sonication of 1-pentene in the presence of Fe(CO)5 produces the thermodynamic mixture of cis and trans... 

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