Carbon, asymmetric monoxide

Normal Fluids. Asymmetrical compounds having Httle molecular interaction, eg, carbon monoxide, / -butane, and / -hexane, deviate slightly from the theory of corresponding states and are considered to be normal fluids. 

Hydrogenated vegetable oil, in cosmetic molded sticks, 7 840t Hydrogenation(s), 13 769 acetylene, 1 180 10 613-614 alkylanthraquinone, 14 47 asymmetric, 5 210—212 butadiene, 4 370 carbon monoxide, 5 3 carbon dioxide, 26 881 catalytic, 10 504 catalytic aerogels for, l 763t chlorocarbons, 6 235 conditions of, 10 810 cyclopentadiene and dicyclopentadiene, 8 224-225... 

An Rh-catalyzed asymmetric [4 +l]-cycloaddition of vinylallenes with carbon monoxide was realized for the first time to furnish chiral 5-substituted 2-alkylidene-3-cydopentenones (Scheme 16.42) [42],... 

The hydroformylation reaction ( oxo reaction ) of alkenes with hydrogen and carbon monoxide is established as an important industrial tool for the production of aldehydes ( oxo aldehydes ) and products derived there from [1-6]. This method also leads to synthetically useful aldehydes and more recently is widely applied in the synthesis of more complex target molecules [7-15,17], including stereoselective and asymmetric syntheses [18-22]. 

Abstract The transition metal mediated conversion of alkynes, alkenes, and carbon monoxide in a formal [2 + 2+1] cycloaddition process, commonly known as the Pauson-Khand reaction (PKR), is an elegant method for the construction of cyclopentenone scaffolds. During the last decade, significant improvements have been achieved in this area. For instance, catalytic PKR variants are nowadays possible with different metal sources. In addition, new asymmetric approaches were established and the reaction has been applied as a key step in various total syntheses. Recent work has also focused on the development of CO-free conditions, incorporating transfer carbonylation reactions. This review attempts to cover the most important developments in this area. 

Mirkin and coworkers reported on catalytic molecular tweezers used in the asymmetric ring opening of cyclohexene oxide. In this case the early transition metal is the catalyst and rhodium functions as the structural inductor metal. The catalyst consists of two chromium salen complexes, the reaction is known to be bimetallic, and a switchable rhodium complex, using carbon monoxide as the switch. Indeed, when the salens are forced in dose proximity in the absence of CO the rate is twice as high and the effect is reversible [77]. 

The electron affinity of the metal surface is low in comparison with the tendency of the foreign molecule to receive electrons. This tendency is particularly high if the electron shell of the adsorbed molecule is incomplete (e.g. as in an oxygen atom) or if the bond of the atoms in the molecule is affected by an asymmetric electron shift (e.g, as in the molecules of nitrous oxide or carbon monoxide). In such cases the metal electrons become part of the electron shell of the foreign molecule. 

In carbon monoxide the bond between the atoms depends, as in the N2O molecule, on an asymmetrical electron shift, electrons of the 0 atom moving toward the C atom, and the CO molecule having a dipole character. In this case, too, metal electrons are displaced toward the adsorbed molecule and taken from the electron gas, as shown by the change of the electrical resistance of thin nickel films on carbon monoxide adsorption (18). 

As illustrated in Scheme 47, various group-VIII metals catalyze the hy-droformylation of olefins by using hydrogen and carbon monoxide to form aldehyde products. Although industrial oxo processes use Co catalysts, the asymmetric reactions use mainly Rh(I)- or Pt(II)-based catalysts. 

The prevailing chirality of the aldehyde produced using ( — )-DIOP as the asymmetric ligand is [ (R) ] for vinyl olefins where the asymmetric carbon atom arises from the attack of carbon monoxide at the carbon atom in position 2. The same chirality [ (R) ] is found also for vinylidene olefins where the asymmetric carbon atom arises from the attack of a hydrogen atom on the same carbon atom. 

Finally a very important fact arising from our results is the occurrence of the asymmetric hydroformylation in olefins having C2v symmetry like d -butene. In this case the two faces of the olefin are identical, and the catalyst is evidently able to dissymmetrize the double bond favoring the attack of hydrogen to the re carbon atom and of carbon monoxide to the si carbon atom. A very simple way of looking at this dissymmetriza-tion of the double bond is to assume that the face of the olefin attacked... 

The results do not prove that in the reaction conditions used the alkyl formation is not reversible, but only that, if it is reversible, the carbon monoxide insertion on both diastereomeric rhodium-alkyls must be much faster than the rhodium-alkyls decomposition. Restricting this analysis of the asymmetric induction phenomena to the rhodium-alkyl complexes formation, two 7r-olefin complexes are possible for each diastereomer of the catalytic rhodium complex (see Scheme 11). The induction can take place in the 7r-olefin complexes formation (I — II(S) or I — II(R)) or in the equilibrium between the diastereomeric 7r-olefin complexes (II(r) and... 

Meiler and Pfeifer (493) measured 13C and H NMR spectra of carbon monoxide, carbon dioxide, and benzene adsorbed on ZSM-5 and silicalite. The 13C signal from benzene was a superimposition of two lines corresponding to relatively mobile molecules (narrow Lorentzian line) and strongly adsorbed molecules (broad asymmetric line similar to that in polycrystalline benzene). Quantitative interpretation of the spectrum was possible via the measurement of the transverse proton relaxation times, T2, as a function of temperature and coverage. Recent work involving 13C NMR studies of sorbed species is summarized in Table XX. 

This section summarizes recent advances in the asymmetric copolymerization of 1-alkene and carbon monoxide, giving the corresponding head-to-tail isotactic copolymer with high regio- and enantioselectivity as well as tacticity. 

The first successful example of asymmetric copolymerization of propene with carbon monoxide was reported in 1992 and used a Pd complex with a chiral electron-rich bisphosphine... 

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