Carbonyl compounds alcohols from

Fig. 1. Production of carbonyl compounds from alcohols by various oxidation routes.

A closely related method does not require conversion of enantiomers to diastereomers but relies on the fact that (in principle, at least) enantiomers have different NMR spectra in a chiral solvent, or when mixed with a chiral molecule (in which case transient diastereomeric species may form). In such cases, the peaks may be separated enough to permit the proportions of enantiomers to be determined from their intensities. Another variation, which gives better results in many cases, is to use an achiral solvent but with the addition of a chiral lanthanide shift reagent such as tris[3-trifiuoroacetyl-Lanthanide shift reagents have the property of spreading NMR peaks of compounds with which they can form coordination compounds, for examples, alcohols, carbonyl compounds, amines, and so on. Chiral lanthanide shift reagents shift the peaks of the two enantiomers of many such compounds to different extents. 

This article shows a variety of patterns of electrochemical oxidation of oxygen-containing compounds (alcohols, carbonyl compounds, and carboxylic acids), aiming to be helpful for both electroorganic and organic chemists to cover this field from a synthetic viewpoint. Since there have been excellent books [1-5] published on the subject, this article quotes only some typical and important papers from before 1990. 

Direct electrochemical oxidation is not a convenient way for a preparative production of carbonyl compounds from alcohols due to the unselectivity caused by the high oxidation potentials of alcohols. Thus, there have been only a few compounds (some aliphatic alcohols, glycols, and related alcohols) that have been oxidized by the direct method, while the indirect method has often been used to oxidize selectively a variety of alcohols, since it does not... 

Hydroperoxide formation is characteristic of alkenes possessing tertiary allylic hydrogen. Allylic rearrangement resulting in the formation of isomeric products is common. Secondary products (alcohols, carbonyl compounds, carboxylic acids) may arise from the decomposition of alkenyl hydroperoxide at higher temperature. 

Keto amides (see Dicarbonyl compounds) Keto esters (see Dicarbonyl compounds) Ketones (see also Dicarbonyl compounds, Unsaturated carbonyl compounds) From alcohols by oxidation... 

In Eq. (3) [S]o and [S]f are starting and ending substrate concentrations. S approaches [S] when substrate consumption is minimal, and S is substituted for [S] to correct for excess substrate consumption. In these analyses, however, substrate inhibition can be a problem if the product has a similar affinity to the substrate. Fortunately, most P450 oxidations produce products that are less hydrophobic than the substrates, resulting in lower affinities to the enzymes. There are exceptions, including desaturation reactions that produce alkenes from alkanes (10) and carbonyl compounds from alcohols. These products have hydrophobicities that are similar or increased relative to their substrates. 

N03)j, a newcomer to the arena of oxidants, is useful for the acetoxylation of aromatic side chains in benzylic positions [415, 416] and for the oxidation of methylene or methyl groups that are adjacent to aromatic rings to carbonyl groups [238, 415, 417]. The reagent also oxidizes alcohols to aldehydes [418, 419, 420, 421] and phenols to quinones [422, 423], cleaves vicinal diols to ketones and a-hydroxy ketones to acids [424, 425], and converts diaryl sulfides into sulfoxides [426]. A specialty of ammonium cerium nitrate is the oxidative recovery of carbonyl compounds from their oximes and semicarbazones [422, 427] and of carboxylic acids from their hydrazides [428] under mild conditions. 

Zinc dichromate tiihydrate, ZnCr207<3H20, is obtained as an orange-red solid by adding zinc carbonate to a cold solution of chromium trioxide in dilute sulfuric acid [660]. The applications are oxidations of acetylenes lo a-diketones, of aromatic hydrocarbons to quinones, of alcohols to aldehydes, and of ethers to esters and the oxidative regeneration of carbonyl compounds from their oximes [660]. 

The combination of reactions described above (Sections 2.6.4.2 to 2.6.4.5) allows the selective synthesis of a large variety of alcohols, allyl alcohols, alkenes, epoxides and carbonyl compounds from p-hydroxyalkyl selenides. These products often can be obtained from two ca nyl compounds by activation of one of them as an a-selenoalkyllithium (Schemes 161-196). 

Fission by aqueous-alcoholic sodium hydrogen sulfite solution is recommended as an elegant method for regenerating carbonyl compounds from their oximes in high yield.951... 

Irradiation of acetophenone and acetaldehyde in THF or diethyl ether gives diastereoisomeric alcohols (15) or (16), formed by hydrogen abstraction of the carbonyl compound from the ether, followed by combination of the radicals... 

Miscellaneous Reactions. In addition to the key reactions above, DDQ has been used for the oxidative removal of chromium, iron, and manganese from their complexes with arenes and for the oxidative formation of imidazoles and thiadia-zoles from acyclic precursors. Catal)ftic amounts of DDQ also offer a mild method for the oxidative regeneration of carbonyl compounds from acetals, which contrasts with their formation from diazo compounds on treatment with DDQ and methanol in nonpolar solvents. DDQ also provides effective catalysis for the tetrahydropyranylation of alcohols. Furthermore, the oxidation of chiral esters or amides of arylacetic acid by DDQ in acetic acid provides a mild procedure for the synthesis of chiral a-acetoxy derivatives, although the diastereoselectivity achieved so far is only 65-67%. ... 

Gogoi, P. Konwar, D. Das Sharma, S. Gogoi, P. K. AICI3.6H2O/KI/CH3CN/H2O. An efficient and versatile system for chemoselective C-O bond cleavage and formation of halides and carbonyl compounds from alcohols in hydrated media. Syrah. Commun. 2006, 36, 1259-1264. 

Molecules derived from carboxylic acid are soluble in solvents (e.g., chlorinated alkanes and aromatic hydrocarbons). Moreover, similar to alcohols, carbonyl compounds with fewer than four carbons are soluble in water (Bruice, 2004). However, the solubility of esters in water decreases together with the increase of the chain length. As a result, none of the fats and oils (triesters of glycerol) are water soluble. 

Formulate a synthesis of each of the following carbonyl compounds from the corresponding alcohol. 

Primary alcohols can be identified by oxidizing them to aldehydes with chromic acid or potassium permanganate in the presence of 2 n sulfuric acid. The aldehyde formed can be isolated by distillation and identified in the form of its dimedone derivative (see p. 230). Primary alcohols can be identified in this manner in the presence of secondary and tertiary alcohols, because dimedone condenses only with aldehydes, i.e., with products of a mild oxidation of primary alcohols. Carbonyl compounds can be isolated from an aqueous distillate by precipitating them with 2,4-dinitrophenyl-hydrazine (see p. 218). If paper chromatography cannot be used for identification (see p. 222), it is advisable to oxidize at least 500 mg of alcohol. 

Until very recently, it was very difficult to prepare carbonyl compounds from alcohols with strong electron-withdrawing groups adjacent to the RCHOH moiety. For instance, 2,2,2-trifluoroethanol is often used as a solvent in oxidation reactions since it has been considered inert to the oxidation. However, the aerobic oxidation of inert perfluoro-substituted alcohols to their corresponding carbonyl derivatives has been recently achieved using Pt(II) complexes with dipyrido[3,2-a 20,30-c]-phenazine ligands (Scheme 10). ° Thus, in the presence of H2SO4 and O2 oxidant, trifluoroethanol was successfully oxidized to trifluoroethyl trifluoracetate with >98% selectivity. 

Chakraborty TK, Purkait S, Das S. Synthesis of chiral 4-hydroxy-2,3-unsaturated carbonyl compounds from 3,4-epoxy alcohols by oxidation appHcation in the formal synthesis of macrosphelide A. Tetrahedron 2003 59 9127 9135. 

The formation of carbonyl compounds from alcohols most likely involves a Bri transfer from reagent to substrate. This oxidation method has an additional advantage that it does not require highly specialized equipment and expensive reagents. The reaction is fast and easy to perform under mild reaction conditions, there is no side product formation and it is completed in very less reaction time. A wide range of aliphatic and benzyhc alcohols can be converted to their corresponding aromatic aldehydes and ketones. 

Formation of a,p-unsaturated carbonyl compounds from propargylic alcohols was described in 2007 by Chung et al. [119] and from propargylic acetates by Nolan and co-workers (Scheme 8) with [(NHC)Au ] complexes [120]. The presence of water was required for the formation of the desired products. Steric hindrance of the ligand appeared to be crucial for the selectivity of the reaction. The reaction was not... 

Suspend 0 25 g. of 2 4-dinitrophenylhydrazine in 5 ml. of methanol and add 0-4 0-5 ml. of concentrated sulphuric acid cautiously. FUter the warm solution and add a solution of 0 1-0-2 g. of the carbonyl compound in a small volume of methanol or of ether. If no sohd separate within 10 minutes, dUute the solution carefuUy with 2N sulphuric acid. CoUect the solid by suction filtration and wash it with a little methanol. RecrystaUise the derivative from alcohol, dUute alcohol, alcohol with ethyl acetate or chloroform or acetone, acetic acid, dioxan, nitromethane, nitrobenzene or xylene. 

When semicarbazide Ls heated in the absence of a carbonyl compound for long periods, condensation to blurea, NHjCONHNHCONHj, m.p. 247-250 (decomp.), may result occasionally this substance may be produced in the normal preparation of a semicarbazone that forms slowly. Biurea is sparingly soluble in alcohol and soluble in hot water, whereas semicarbazones with melting points in the same range are insoluble in water this enables it to be readily distinguished from a semicarbazone. 

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