Ketones carbon monoxide formation

The resulting anion undergoes insertion with carbon monoxide or ketone formation with acyl halides in a manner similar to alkylchlorozirconocenes (Section 31-3A) ... 

Figure 5. Quantum yields for carbon monoxide formation in ketones of type O...

Norrish Type I cleavage reactions dominate in the gas phase photochemistry of many acyclic aldehydes and ketones, whereas in the liquid phase this process is less common and alternative pathways (ii, iii, v) dominate. When no suitable C-H bonds are present to allow hydrogen abstraction reactions, however, this process will also constitute an important synthetic method for the cleavage of a-C-C bonds in solution. One important subsequent reaction of the resulting acyl and alkyl radicals is carbon monoxide formation and radical combination. Overall CO extrusion results which represents a versatile method for the formation of C-C single bonds from ketones. When cyclic substrates (cycloalkanones but not conjugated cycloalkenones which exhibit a different photochemistry) are used, ring... 

Aldehydes show an elimination reaction (loss of carbon monoxide, CO), that is not possible with ketones. Butanal, for example, photodissociates to propane and carbon monoxide. Cyclic ketones dissociate to a diradical (41 from cyclopentanone), which then reacts in any of several ways including elimination to ethene or 42 and coupling to cyclobutane. Formation of cyclobutane and ethene is accompanied by expulsion of CO prior... 

In the Fischer-Tropsch process, carbon monoxide reacts with hydrogen in the presence of a solid catalyst, with the formation of a mixture of hydrocarbons. The composition of the product varies considerably with the catalyst and the operating conditions. The mixture may include (in addition to hydrocarbons) alcohols, aldehydes, ketones, and acids. 

Scheme 7 comprises the following patterns First, a metallacycle gives rise to ketones by CO insertion and reductive elimination. Next, a nickel hydride inserts an unsaturated substrate L, followed by CO. The acyl intermediate can give rise to reductive elimination with formation of acyl halides or acids and esters by hydrolysis, or it can insert a new ligand with subsequent reductive elimination as before. Alternatively, there may be a new insertion of carbon monoxide with final hydrolysis. Third, an intermediate R—Ni—X is formed by oxidative addition. It can react in several ways It can insert a new ligand L, followed by CO to give an... 

Five- or six-membered saturated cyclic ketones can also react by another pathway that does not involve decarbonylation. In these reactions, the biradical initially formed by a-cleavage undergoes internal disproportionation without loss of carbon monoxide, resulting in the formation of either an unsaturated aldehyde or a ketene. Methanol is usually added to convert the reactive ketene to a stable carboxylic-acid derivative (Scheme 9.2). 

Catalytic processes based on the use of electrogenerated nickel(O) bipyridine complexes have been a prominent theme in the laboratories of Nedelec, Perichon, and Troupel some of the more recent work has involved the following (1) cross-coupling of aryl halides with ethyl chloroacetate [143], with activated olefins [144], and with activated alkyl halides [145], (2) coupling of organic halides with carbon monoxide to form ketones [146], (3) coupling of a-chloroketones with aryl halides to give O -arylated ketones [147], and (4) formation of ketones via reduction of a mixture of a benzyl or alkyl halide with a metal carbonyl [148]. 

Under more vigorous conditions, complex XII can apparently add more acetylene and carbon monoxide, forming a bifurandione, XIII (/, 79, 82). A reasonable mechanism for the dione formation would be a CO insertion, then an acetylene insertion, and another CO insertion, followed by cyclization by ketone insertion, and finally a Co2(CO)3 elimination. 

The treatment of the mercurio ketone with palladium (II) in the presence of carbon monoxide and methanol, Eq. (27) results in the formation of a y-keto ester with incorporation of one molecule of carbon monoxide [8], The overall conversion of a siloxycyclopropane to the keto ester may be performed without isolation of the mercurio ketone. 

The insertion of carbon monoxide into azolylpalladium complexes proceeds readily and in most cases leads to the formation of carboxylic acid derivatives or ketones. In a modified version of the carbonylation 3-bromothiophene was reacted with carbon monoxide in the presence of sodium formate. This reagents converts the intermediate acylpalladium formate complex, through the release of carbon dioxide into the acylpalladium hydride (c.f 7.47.), which in turn releases thiophene carboxaldehyde as the sole product (6.62.),92 If sodium formate was replaced... 

The halogenated derivatives of six membered heterocycles, like their carbacyclic analogues, usually participate readily in coupling reactions that involve the incorporation of an olefin or carbon monoxide. The insertion of carbon monoxide commonly leads to the formation of either a carboxylic acid derivative or a ketone, depending on the nature of the other reactants present. Intermolecular and intramolecular variants of the insertion route are equally popular, and are frequently utilized in the functionalization of heterocycles or the formation of annelated ring systems. 

By in situ MAS NMR spectroscopy, the Koch reaction was also observed upon co-adsorption of butyl alcohols (tert-butyl, isobutyl, and -butyl) and carbon monoxide or of olefins (Ao-butylene and 1-octene), carbon monoxide, and water on HZSM-5 (Ksi/ Ai — 49) under mild conditions (87,88). Under the same conditions, but in the absence of water (89), it was shown that ethylene, isobutylene, and 1-octene undergo the Friedel-Crafts acylation (90) to form unsaturated ketones and stable cyclic five-membered ring carboxonium ions instead of carboxylic acids. Carbonylation of benzene by the direct reaction of benzene and carbon monoxide on solid catalysts was reported by Clingenpeel et al. (91,92). By C MAS NMR spectroscopy, the formation of benzoic acid (178 ppm) and benzaldehyde (206 ppm) was observed on zeolite HY (91), AlC -doped HY (91), and sulfated zirconia (SZA) (92). 

Formylation of isobutane with carbon monoxide in the presence of an excess of A1C13 was first reported by Nenitzescu to yield, among others, methyl isopropyl ketone (31%).168 A new highly efficient superelectrophilic formylation-rearrange-ment of isoalkanes by Olah and coworkers has been described.282 Selective formation of branched ketone in high yield with no detectable branched acids, that is, the Koch products, was achieved. A particularly suitable acid is HF—BF3, which transforms, for example, isobutane to methyl isopropyl ketone in 91% yield. The... 

The detection of 1,2-propylene oxide in the products from methyl ethyl ketone combustion is particularly interesting. It parallels the formation of ethylene oxide in acetone combustion (8) and of 1,2-butylene oxide in the combustion of diethyl ketone. Thus, there is apparently a group of isomerization reactions in which carbon monoxide is ejected from the transition state with subsequent closing of the C—C bond. Examination of scale molecular models shows that reactions of this type are, at any rate, plausible geometrically. 

The resonance energy of carbon monoxide relative to the structure C=0 (which itself corresponds to resonance between + C 0 , C O , and C 0 ) can be found by comparing its heat of formation from atoms, 257 kcal/mole, with the ketone value of the doublebond energy, 174 kcal/mole.7 The very large difference, 83 kcal/mole,... 

Experiments on the decomposition of the ketone in the presence of oxygen (Table I) strongly indicate that the formation of ethylene, cyclobutane (and, by inference, carbon monoxide), and pentenal is not affected by even 35.5 mm. of oxygen. This may be compared with the... 

It has been observed that the formation of the olefin and carbon monoxide, 45, is ten times more important than the formation of the bicyclic hydrocarbon and carbon monoxide, 46, at 80° and 80 mm. pressure even at 3130 A. The formation of the strained bicyclic hydrocarbon is evidently not a favorable reaction although this may not be the only consideration. In the case of camphor it should be interesting to find out if an optically active isomer of the ketone on photolysis will give rise to an optically active trimethyl bicyclo [2.1.1] hexane (XXVI). A concerted reaction, analogous to the formation of cyclobutane from cyclopentanone, may lead to only an optically active product. 

The photolysis of camphor (XXII) in aqueous alcoholic solution (11) has been observed to lead to a-campholenic aldehyde (XXXII) and a second isomer with a ketonic function. The structure of the latter has been found (30) to be 1,2,2-trimethyl cyclopent-3-enyl methyl ketone (XXXIII). The quantum yields at 3130 A. for the formation of the two isomers and of carbon monoxide in five different solvents have been determined (Table IV). It is interesting that the sum of the quantum... 

The oxidation of primary or secondary alcohols to aldehydes or ketones respectively with dimethyl sulphoxide activated by oxalyl chloride has wide applicability (Swern oxidation).243b The initial reaction between the acid chloride and dimethyl sulphoxide in dichloromethane solvent is vigorous and exothermic at — 60 °C and results in the formation of the complex (7) this complex spontaneously decomposes, even at this low temperature, releasing carbon dioxide and carbon monoxide to form the complex (8). The alcohol is added within 5 minutes, followed after 15 minutes by triethylamine. After a further 5 minutes at low temperature the reaction mixture is allowed to warm to room temperature and work-up follows standard procedures. The ratio of reactants is dimethyl sulphoxide oxalyl chloride alcohol triethylamine 2.2 1.1 1.0 5. 

Reactions of monomeric and dimeric rhodium(II) porphyrins with carbon monoxide - As already reported in Sect. 3.3, a carbonylrhodium(II) porphyrin behaves as an acyl radical. Hence, if possible, dimerization or coupling reactions occur. Evidence for the formation of isomeric 2 1 Rh(P) CO adducts, namely a monoadduct of the dimer and a metallo ketone complex, and a dimeric 1 1 adduct in the reaction of [Rh(OEP)]2 with carbon monoxide according to sequences (38) and (39) has been presented [340,341] solution equilibria and structures have been studied essentially by lHNMR, 13CNMR, and IR spectroscopy. The first half of sequence (38) and reaction (39) occurred in parallel at CO pressures up to 12 atm at 297 K. At higher pressures, or at lower temperatures, the double-insertion of CO shown in the last step of (38) was observed. 

Nickel carbonyl is the more widely known catalyst for the carboxylation reaction dicobalt octacarbonyl has the disadvantage of giving side reactions (15). Dicobalt octacarbonyl has been used in the presence of tributyl phosphine for the reaction of ethylene, carbon monoxide, water, and ethanol. Besides ethyl acetate, acetaldehyde and diethyl ketone were found (136). Hydrogen has been found to increase the rate of reaction (78), presumably by the formation of cobalt hydrocarbonyl. However, this can lead to the formation of aldehydes, as in the reaction of acetyl bromide when an 89.4% yield of aldehyde was obtained in spite of the presence of water (95). 

When nonconjugated dienes react with carbon monoxide and water in the presence of dicobalt octacarbonyl, saturated and unsaturated cyclic ketones are produced (55, 77). This appears to be due to the formation of unsaturated acylcobalt carbonyls followed by cyclization, as discussed in Section II, B,3. 

Fig. 8.4 (a) shows the response of the oxygenate sensor-1 (Sn02 sensitized with Ti02) towards an alcohol (1-propanol), aldehyde (propanal), ketone (acetone), carbon monoxide (CO) and propane. The sensor is sensitive to the alcohol, aldehyde and ketone but not to CO and propane. Conversely, oxygenate sensor 2 (Sn02 sensitized with 13 wt% Si02/Al203) is less sensitive to the alcohol than aldehyde (Fig. 8.4b). Alcohol formation can thus be estimated from a comparison of the output signals of oxygenate sensors 1 and 2.

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