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Aldehydes reagents and

Fig. 5.14 Electrochemical carboxylation of aldehydes. Reagents and conditions divided flow cell, Nation membrane, BDD/Si electrodes, NBu4+BF4 in DMF, 20-25°C, 0.6 A dm-2, 5h, 27% yield in rac-28 at 88% conversion of 27... Fig. 5.14 Electrochemical carboxylation of aldehydes. Reagents and conditions divided flow cell, Nation membrane, BDD/Si electrodes, NBu4+BF4 in DMF, 20-25°C, 0.6 A dm-2, 5h, 27% yield in rac-28 at 88% conversion of 27...
An interesting consideration relating to the influence of acidity in the reaction medium is derived from the comparison between the conditions adopted for the synthesis of the P-aminoketoncs 44 and 45, and tho.se required for the analogous derivatives that lack the carboxy group. Whereas the latter compounds are prepared under the. severe conditions of type A (Table 6), both the syntheses of 44, employing glyoxal as aldehyde reagent,and that of 45, which is prepared from 3-benzoyl propionic acid, take place readily under mild conditions (type B or C). [Pg.15]

Finally, it has also to be mentioned that enolizable a,p-unsaturated aldehydes have also been employed as Michael donors in this context (Scheme 2.18). This reaction proceeds via formation of a dienamine nucleophilic intermediate, which undergoes regioselective a-addition leading to the formation of the corresponding Michael adduct containing an a-substituted p,y-unsatu-rated aldehyde moiety. The conditions had to be carefully optimized and required the use of a y,y-disubstituted a,p-unsaturated aldehyde reagent and involved the use of catalyst 31a in the presence of AcOH as Bronsted acid cocatalyst and acetonitrile as solvent. In situ reduction of the Michael adducts was... [Pg.41]

Flo. 9. Nature of inhibition between aldehyde reagents and cytochrome c. Ordinate—reciprocal of the oxygen uptake in the first 15 minutes abscissa— reciprocal of the molar concentration of cytochrome c in the reaction mixture. [Pg.438]

To clarify the mode of inhibition, the reaction was analyzed by the method of Lineweaver and Burk (1934) at two concentrations of aldehyde reagents and five concentrations of cytochrome c. The data were plotted by the double reciprocal procedure and the inhibition was found to be both competitive and noncompetitive in type. [Pg.439]

Separations based upon differences in the chemical properties of the components. Thus a mixture of toluene and anihne may be separated by extraction with dilute hydrochloric acid the aniline passes into the aqueous layer in the form of the salt, anihne hydrochloride, and may be recovered by neutralisation. Similarly, a mixture of phenol and toluene may be separated by treatment with dilute sodium hydroxide. The above examples are, of comse, simple apphcations of the fact that the various components fah into different solubihty groups (compare Section XI,5). Another example is the separation of a mixture of di-n-butyl ether and chlorobenzene concentrated sulphuric acid dissolves only the w-butyl other and it may be recovered from solution by dilution with water. With some classes of compounds, e.g., unsaturated compounds, concentrated sulphuric acid leads to polymerisation, sulphona-tion, etc., so that the original component cannot be recovered unchanged this solvent, therefore, possesses hmited apphcation. Phenols may be separated from acids (for example, o-cresol from benzoic acid) by a dilute solution of sodium bicarbonate the weakly acidic phenols (and also enols) are not converted into salts by this reagent and may be removed by ether extraction or by other means the acids pass into solution as the sodium salts and may be recovered after acidification. Aldehydes, e.g., benzaldehyde, may be separated from liquid hydrocarbons and other neutral, water-insoluble hquid compounds by shaking with a solution of sodium bisulphite the aldehyde forms a sohd bisulphite compound, which may be filtered off and decomposed with dilute acid or with sodium bicarbonate solution in order to recover the aldehyde. [Pg.1091]

Secondary alcohols may be prepared by two different combinations of Grignard reagent and aldehyde... [Pg.599]

Organozmc reagents are not nearly as reactive toward aldehydes and ketones as Grig nard reagents and organolithium compounds but are intermediates m certain reactions of alkyl halides... [Pg.604]

Addition of Grignard reagents and organolithium compounds (Sections 14 6-14 7) Aldehydes are converted to secondary alcohols and ketones to tertiary alcohols... [Pg.713]

We ve seen how Grignard reagents add to the carbonyl group of aldehydes ketones and esters Grignard reagents react m much the same way with carbon dioxide to yield mag nesium salts of carboxylic acids Acidification converts these magnesium salts to the desired carboxylic acids... [Pg.806]

Oxidation. Oxidation of hydroxybenzaldehydes can result in the formation of a variety of compounds, depending on the reagents and conditions used. Replacement of the aldehyde function by a hydroxyl group results when 2- or 4-hydroxybenzaldehydes are treated with hydrogen peroxide in acidic (42) or basic (43) media pyrocatechol or hydroquinone are obtained, respectively. [Pg.505]

Sofid sodium permanganate monohydrate has been shown to be a selective synthetic reagent (156). It is typically used in hexane for the heterogeneous oxidation of aldehydes, alcohols, and sulfides. Synthetic methodology based on crystal surfaces exhibited greater selectivity, higher yield, and easier work-up as compared to aqueous permanganate reactions. [Pg.522]

BODROUX - CHICHIBABtN Aldehyde synthesis Aldehyde synthesis Irom Grignard reagents and trialkyl oitholormate... [Pg.39]

Distillation is required to remove aldehyde, alcohol, and water which would react with the Grignard reagent in the next step. a,d-Dibromoethyl ethyl ether is also a lachrymator. [Pg.63]

Lithium aluminum hydride (LiAlH4) is the most powerful of the hydride reagents. It reduces acid chlorides, esters, lactones, acids, anhydrides, aldehydes, ketones and epoxides to alcohols amides, nitriles, imines and oximes to amines primary and secondary alkyl halides and toluenesulfonates to... [Pg.61]

Primary and secondary amines, double bonds, aldehydes, sulfides and certain aromatic and dihydroaroraatic systems are also oxidized by chromium VI reagents under standard hydroxyl oxidizing conditions. Amines are commonly protected by salt formation or by conversion to amides. Aldehydes and... [Pg.226]

A recently discovered (2) oxidizing system promises to become very important for the oxidation of acid-sensitive compounds. The reagent is chromium trioxide-pyridine complex, which may be isolated after preparation and employed in nonaqueous solvents (usually methylene chloride). A remarkable feature of the reagent is that good yields of aldehydes are obtained by direct oxidation of primary alcohols. The preparation of the reagent and its use are given. [Pg.3]

On treatment with a strong base such as sodium hydride or sodium amide, dimethyl sulfoxide yields a proton to form the methylsulfinyl carbanion (dimsyl ion), a strongly basic reagent. Reaction of dimsyl ion with triphenylalkylphosphonium halides provides a convenient route to ylides (see Chapter 11, Section III), and with triphenylmethane the reagent affords a high concentration of triphenylmethyl carbanion. Of immediate interest, however, is the nucleophilic reaction of dimsyl ion with aldehydes, ketones, and particularly esters (//). The reaction of dimsyl ion with nonenolizable ketones and... [Pg.92]


See other pages where Aldehydes reagents and is mentioned: [Pg.46]    [Pg.377]    [Pg.432]    [Pg.438]    [Pg.92]    [Pg.46]    [Pg.377]    [Pg.432]    [Pg.438]    [Pg.92]    [Pg.19]    [Pg.330]    [Pg.446]    [Pg.889]    [Pg.1061]    [Pg.1061]    [Pg.47]    [Pg.325]    [Pg.53]    [Pg.397]    [Pg.287]    [Pg.511]    [Pg.493]    [Pg.342]    [Pg.154]    [Pg.133]    [Pg.177]    [Pg.55]    [Pg.416]    [Pg.296]    [Pg.35]    [Pg.101]    [Pg.184]    [Pg.197]   
See also in sourсe #XX -- [ Pg.916 ]




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Aldehydes reagents

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