Ketones, saturated, carbon monoxide

Carbon monoxide has been identified as the primary cause of death of most fire victims. Apart from carbon monoxide and carbon dioxide, the evolved products from PP in a fire include pyrolysis products, which are primarily saturated aliphatics, and combustion products, which are mainly a mixture of simple and complex aldehydes and ketones. However, carbon monoxide is generally considered to be the principal resulting toxicant from burning PP. The LCjg value (for definition, see later) measured for PP is 17 mgl and the severity of toxicity associated with PP is considered similar to PE and no worse than wood [4]. It is generally accepted that PP is one of the polymers with least toxic potential in a fire situation because of its simple hydrocarbon structure [1]. 

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). 

Sulphuric acid (concentrated). Widely used in desiccators. Suitable for drying bromine, saturated hydrocarbons, alkyl and aryl halides. Also suitable for drying the following gases hydrogen, nitrogen, carbon dioxide, carbon monoxide, chlorine, methane and paraffins. Unsuitable for alcohols, bases, ketones or phenols. Also available with an indicator (a cobalt salt, blue when dry and pink when wet) under the name Sicacide (from Merck) for desiccators. 

R = H or Me) (59,62). It is interesting that this reaction proceeds readily in solution since reactions in which carbon monoxide is eliminated from a saturated ketone usually occur in the vapor phase. 

Saturated ketones undergo a large number of photochemical reactions which include photoreduction, elimination of a-heterosubstituents, a-cleavage, 7-hydrogen transfer, and elimination of carbon monoxide. In this chapter only photochemical rearrangements of saturated ketones will be considered. 

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. 

Palladium-catalyzed ketone synthesis B. The reaction mixture is saturated with carbon monoxide, which intervenes in step 2 by forming a palladium(II) carbonyl complex. Before the transmetalation (above referred to as step 3) takes place a rearrangement is interposed. The ligand Rmisa rji cd undergoes a [l,2]-shift from Pd(II) to the carbon atom of carbon monoxide, leading to the formation of an acylpalladium(II) complex with the structure P lllsa llra cd-(C=0)-Pd(-X) L j. With regard to the above-mentioned steps 3-4 it behaves like the acyl-Pd(II) complex of the ketone synthesis A and, after reductive elimination, i.e. in step 5, yields... 

Oxo Chemicals. The so-called oxo process combines carbon monoxide and hydrogen with olefins to make saturated aldehydes having one more carbon atom than the olefins have. The earliest such reaction studied used ethylene to produce both an aldehyde and a ketone. 

The aromatic borepins and benzoborepins have been prepared primarily as compounds of theoretical interest and no significant applications have been reported to date. Saturated 1-alkylborepanes, such as 23 and similar large ring boron compounds, are of use primarily as precursors in the synthesis of cyclic ketones by treatment with carbon monoxide followed by alkaline hydrogen peroxide <1982JOC1792>. 

The preparation of the C1-C21 subunit of the protein phosphatase inhibitor tautomycin was completed by J.A. Marshall et al., and it constituted a formal total synthesis of the natural product. The spiroketal carbon of the target was introduced by the Weinreb ketone synthesis between a lithioalkyne and A/-methoxy-A/-methylurea (a carbon monoxide equivalent). The triple bond of the resulting Weinreb s amide was first reduced under catalytic hydrogenation conditions to yield the corresponding saturated amide, which was reacted with another lithium acetylide to afford an ynone. 

When a further double bond was present in the C ring, the selectivity was inverted Enamines of cyclic and linear ketones were reduced to the corresponding saturated amines by hydridotetracarbonylferrate under carbon monoxide °,... 

With alkynes hydrocarbonylative coupling leads to unsaturated ketones with exclusive cis addition of hydrogen and the acyl group. Thus, rhodium carbonyl catalyzed carbonylation of acetylenes and ethene with carbon monoxide and hydrogen stereospecifically leads to a./l-un-saturated ethyl ketones by cross hydrocarbonylation4- 5, e.g., diphenylacetylene with ethene in the presence of Rh4(CO)l3 gives ( )-1.2-diphenyl-l-penten-3-one in 91 % yield5. 

The elimination of carbon monoxide from cyclic ketones is a fairly common process. The reaction occurs photochemically with saturated systems the mechanism of this process was discussed in Part A, Section 11.3. Facile thermal expulsion occurs only in molecules having special structural features. The elimination of carbon monoxide from bicyclo[2.2.1]heptadien-7-ones can occur by a concerted mechanism. In fact, generation of bicyclo[2.2.1]heptadien-7-ones is usually accompanied by... 

The second step is the analysis of the gas mixture by any available traditional or modern instrumental techniques. Carbon monoxide and dioxide, sulphur dioxide, hydrogen chloride, hydrogen cyanide as well as saturated and unsaturated hydrocarbons and their oxidation products (such as alcohols, aldehydes, ketones, carboxylic acids) are determined mainly by gas chromatography with the occasional contribution of infrared spectroscopy and mass spectrometry. 

In 2002 a process for the direct carbonylation of saturated hydrocarbons has been patented (83). The process involves contacting the saturated hydrocarbons, which contain at least one primary, secondary or tertiary carbon atom, with carbon monoxide in the presence of a strong solid acid catalyst to produce an oxygenated saturated hydrocarbon. However, the observed conversions were small. For example, 119 g of isobutane, reacted at 100° C for 12 h with carbon monoxide (68 atm) using sulfated zirconia as the catalyst, produced only 0.14 g of pivalic acid and 0.007 g of methylisopropyl ketone. 

When simple saturated substrates are exposed to heat in the absence of oxygen, predictable pattern of compounds such as hydrocarbons, free fatty acids or symmetric ketones are produced. The specific thermolytic products depend on the chain length of the parent fatty acid in the TAG molecule. A simple TAG produces ( =number of carbons in the fatty acid moiety) a series of normal alkanes and 1-alkenes with the C j alkane predominating a fatty acid, a symmetric ketone a oxopropyl ester propene and propanediol diesters and diacylglycerols. In addition, acrolein, carbon monoxide and carbon dioxide are also formed (Nawar, 1985). 

Hydroformylation is the reaction of an unsaturated compound (or a saturated compound which may generate an unsaturated compound) with carbon monoxide and hydrogen to yield an aldehyde. The reaction was discovered by O. Roelen in the laboratories of Ruhrchemie AG, Oberhau-sen-Holten in 1938 [21-23] when he tried to recycle olefins to the Fischer-Tropsch synthesis reactor. As reaction products he isolated oxygen-containing compounds which proved to be aldehydes and ketones. Roelen started extensive investigations with ethylene and obtained propionalde-hyde and diethylketone as main products. 

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