Ketones aliphatic saturated

If the alkyl dciivativcs of the ester aie employed, it is possible to effect the synthesis of a series of ketones and saturated aliphatic acids, according to whcthci the one or other 1 ( ac tion is used. 

Viologen salts act as one-electron phase-transfer agents and, in conjunction with sodium dithionite which regenerates the bipyridinium radical cation, they have been used for the debromination of 1,2-dibromoalkanes to yield alkenes in variable yields [13-15]. Nitroarenes are reduced to anilines in high yield (>90%) under similar conditions [16], whereas conjugated nitroalkenes are converted into the oximes of the saturated ketones [17] saturated aliphatic nitro compounds are not reduced by this process. 

Electrocatalytic hydrogenation has the advantage of milder reaction conditions compared to catalytic hydrogenation. The development of various electrode materials (e.g., massive electrodes, powder cathodes, polymer film electrodes) and the optimization of reaction conditions have led to highly selective electrocatalytic hydrogenations. These are very suitable for the conversion of aliphatic and aromatic nitro compounds to amines and a, fi-unsaturated ketones to saturated ketones. The field is reviewed with 173 references in [158]. While the reduction of conjugated enones does not always proceed chemoselectively at a Hg cathode, the use of a carbon felt electrode coated with polyviologen/Pd particles provided saturated ketones exclusively (Fig. 34) [159]. 

Group 10 is a fairly small group covering secondary aliphatic saturated or unsaturated alcohols, ketones, ketals and esters. Important members are the typical dairy compounds diacetyl (Flavis 07.052, FEMA 2370) and acetoin (Flavis 07.051, FEMA 2370). 

Ill) Conjugated Aldehyde, Acid, Ester, Nitrile, Nitro Functions. Double bond hydrogenation of a,)3-unsaturated potentially reducible groups other than ketones is also possible. Aliphatic saturate aldehydes are obtained in high yields by reduction over Pd,... 

When pure water vapour is used as the mobile phase, the components of a mixture can be separated according to the functional groups present. For example, below 130°C, on the crystallohydrate Mg(N03)2 -bHiO (m.p. 85°C) the retention order is aliphatic saturated and unsaturated hydrocarbons < aromatic hydrocarbons < polar compounds. The elution order of ketones, ethers, esters, alcohols and acids is dependent on their polarity. The elution order of the n-alcohols is pentanoK butanoK propanoK ethanol < methanol this unexpected order probably results from hydrogen bond formation between the water of crystallization and the molecules of the compounds to be separated. 

The carbonyl compounds that can undergo this condensation include aliphatic, aromatic, and <%,/ -unsaturated aldehydes, aliphatic, saturated carbo-cyclic, and aromatic ketones, diketones, oxo esters, and cyano ketones. Sodium ethoxide and potassium terf-butoxide are the condensing agents generally used. 

In the Diels-Alder reaction with inverse electron demand, the overlap of the LUMO of the 1-oxa-l,3-butadiene with the HOMO of the dienophile is dominant. Since the electron-withdrawing group at the oxabutadiene at the 3-position lowers its LUMO dramatically, the cycloaddition as well as the condensation usually take place at room or slightly elevated temperature. There is actually no restriction for the aldehydes. Thus, aromatic, heteroaromatic, saturated aliphatic and unsaturated aliphatic aldehydes may be used. For example, a-oxocarbocylic esters or 1,2-dike-tones for instance have been employed as ketones. Furthermore, 1,3-dicarbonyl compounds cyclic and acyclic substances such as Meldmm s acid, barbituric acid and derivates, coumarins, any type of cycloalkane-1,3-dione, (1-ketoesters, and 1,3-diones as well as their phosphorus, nitrogen and sulfur analogues, can also be ap-... 

Although there are now several catalysts useful for hydrogenation of saturated carbonyl compounds to alcohols (see Section XII), an alternative approach has involved initial hydrosilylation (Chapter 9 in this volume) followed by acid hydrolysis [Eq. (41)]. The area first developed using principally the RhCl(PPh3)3 catalyst (207-210), and has since proved particularly useful in asymmetric syntheses (see Section III,A,4). Besides simple aliphatic and aromatic aldehydes and ketones, the ter-pene-ketones camphor and menthone were stereoselectively reduced to mainly the less stable alcohols e.g., camphor gave 9 (209). 

Oxidative attack on a carbon-hydrogen bond of an alkyl group a to a nitrogen atom is not restricted to saturated aliphatic amines. In fact X in an X-N-CH- structural subunit can be virtually any common atomic grouping that can be found in stable organic molecules. For example, w-carbon hydrogens of Aralkyl-substituted aromatic cyclic amines (119), aryl amines (120), amides (121), amidines (122), A-nitrosodialkylamines (123), etc. are all subject to oxidative attack, carbinolamine formation, and in most cases release of an aldehyde or ketone depending on the substitution pattern (1° or 2°)... 

In the 1970s, Brouwer and Kifflin reported the reactions of saturated hydrocarbons with aliphatic aldehydes and ketones in superacidic media. Analysis of the products from these reactions suggested that the protonated aldehydes and ketones (carboxonium ions) were reacting at the carbon-hydrogen o-bonds of the alkanes. This was a surprising observation because carboxonium... 

As mentioned in Chapter 1, this is one of the best methods for generating a specific enolate of a ketone. The enolate generated by conjugate reduction can undergo the characteristic alkylation and addition reactions which were discussed in Chapters 1 and 2. When this is the objective of the reduction, it is important to use only one equivalent of the proton donor. Ammonia, being a weaker acid than an aliphatic ketone, does not protonate the enolate, and it remains available for reaction. If the saturated ketone is the desired product, the enolate is protonated either by use of excess proton donor during the reduction or on... 

A number of saturated aliphatic and cycloaliphatic ketones can be ethynylated with excellent results by adding the ketone to a suspension of potassium acetylide in THF, while continuously introducing acetylene. The potassium acetylide is first generated by introducing acetylene through a solution of t-BuOK in THF. 

Reduction Carbonyl groups. The carbonyl group (-(C=0)-) is reduced through a reaction that is catalyzed by an aldo-keto reductase requiring NADH as a cofactor. A large number of aromatic and aliphatic ketones are reduced to the corresponding alcohols these reductions are frequently stereospecific. a,P-Unsaturated ketones are typically metabolized to saturated alcohols. 

In a discussion of these effects, it is customary to refer to the absorption frequency of a neat sample of a saturated aliphatic ketone, 1715 cm-1, as normal. For example, acetone and cyclohexanone absorb at... 

Replacement of an alkyl group of a saturated aliphatic ketone by a hetero atom (G) shifts the carbonyl absorption. The direction of the shift depends on whether the inductive effect (a) or resonance effect (b) predominates. 

The lower members of the homologous series of 1. Alcohols 2. Aldehydes 3. Ketones 4. Acids 5. Esters 6. Phenols 7. Anhydrides 8. Amines 9. Nitriles 10. Polyhydroxy phenols 1. Polybasic acids and hydro-oxy acids. 2. Glycols, poly-hydric alcohols, polyhydroxy aldehydes and ketones (sugars) 3. Some amides, ammo acids, di-and polyamino compounds, amino alcohols 4. Sulphonic acids 5. Sulphinic acids 6. Salts 1. Acids 2. Phenols 3. Imides 4. Some primary and secondary nitro compounds oximes 5. Mercaptans and thiophenols 6. Sulphonic acids, sulphinic acids, sulphuric acids, and sul-phonamides 7. Some diketones and (3-keto esters 1. Primary amines 2. Secondary aliphatic and aryl-alkyl amines 3. Aliphatic and some aryl-alkyl tertiary amines 4. Hydrazines 1. Unsaturated hydrocarbons 2. Some poly-alkylated aromatic hydrocarbons 3. Alcohols 4. Aldehydes 5. Ketones 6. Esters 7. Anhydrides 8. Ethers and acetals 9. Lactones 10. Acyl halides 1. Saturated aliphatic hydrocarbons Cyclic paraffin hydrocarbons 3. Aromatic hydrocarbons 4. Halogen derivatives of 1, 2 and 3 5. Diaryl ethers 1. Nitro compounds (tertiary) 2. Amides and derivatives of aldehydes and ketones 3. Nitriles 4. Negatively substituted amines 5. Nitroso, azo, hy-drazo, and other intermediate reduction products of nitro com-pounds 6. Sulphones, sul-phonamides of secondary amines, sulphides, sulphates and other Sulphur compounds... 

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