Sodium reaction with ketones

The reaction with sodium is by no means an infallible practical test for alcohols since, strictly speaking, it is applicable only to pure anhydrous liquids. Traces of water, present as impurities, would give an initial evolution of hydrogen, but reaction would stop after a time if an alcohol is absent furthermore, certain esters and ketones also evolve hydrogen when treated with sodium (compare Section XI,7,6). It may, however, be assumed that if no hydrogen is evolved in the test, the substance is not an alcohol. 

The condensation of aldehydes and ketones with succinic esters in the presence of sodium ethoxide is known as the Stobbe condensation. The reaction with sodium ethoxide is comparatively slow and a httlo reduction of the ketonic compound to the carbinol usually occurs a shorter reaction time and a better yield is generally obtained with the more powerful condensing agent potassium ieri.-butoxide or with sodium hydride. Thus benzophenone condenses with diethyl succinate in the presence of potassium [Pg.919]

For the mechanistic course of the reaction the diketone 5 is assumed to be an intermediate, since small amounts of 5 can sometimes be isolated as a minor product. It is likely that the sodium initially reacts with the ester 1 to give the radical anion species 3, which can dimerize to the dianion 4. By release of two alkoxides R 0 the diketone 5 is formed. Further reaction with sodium leads to the dianion 6, which yields the a-hydroxy ketone 2 upon aqueous workup ... 

Kimura and co-workers have synthesized a series of alkoxide complexes with the alcohol functionality as a pendent arm.447 674 737 A zinc complex of l-(4-bromophenacyl)-l, 4,7,10-tetraaza-cyclododecane was also synthesized by the same workers to mimic the active site of class II aldolases. The X-ray structure shows a six-coordinate zinc center with five donors from the ligand and a water molecule bound. The ketone is bound with a Zn—O distance of 2.159(3) A (Figure 12). Potentiometric titration indicated formation of a mixture of the hydroxide and the enolate. Enolate formation was also independently carried out by reaction with sodium methoxide, allowing full characterization.738... 

The chlorodifluoromethylated ketone 130 proved to be a valuable substrate for promoting SrnI subtitution reaction with sodium phenylthiolate and to generate a new a-(phenylthio)-a,a-difluoroacetophenone derivative 131 (Equation 57) <2001TL3459>. Upon treatment with nitronate anions under classical SrnI reaction conditions or MW irradiation, 6-chloromethyl-5-nitro-imidazo[2,l- ]thiazole 132 yielded 5-nitroimidazothiazoles bearing a trisubstituted ethylenic double bond at the 6-position (Equation 58) <2001SC1257>. 

Nickel(lll) oxide, prepared from a nickel(ii) salt and sodium hypochlorite, is used for the oxidation of alkanols in aqueous alkali [46]. Residual nickel(Ii) oxide can be re-activated by reaction with sodium hypochlorite. Nickel oxides have also long been used in the manufacture of the positive pole in the Edison nickel-iron rechargeable battery, now largely superseded by die lead-acid accumulator, and in the Jungner nickel-cadmium batteries used as button cells for calculators [47]. Here, prepared nickel oxide is pressed into a holding plate of perforated nickel. Such prepared plates of nickel(lli) oxide have been proposed as reagent for the oxidation, in alkaline solution, of secondary alcohols to ketones and primary alcohols to carboxylic acids [48]. Used plates can be regenerated by anodic oxidation. 

Two years later, the same group reported a formal synthesis of ellipticine (228) using 6-benzyl-6H-pyrido[4,3-f>]carbazole-5,ll-quinone (6-benzylellipticine quinone) (1241) as intermediate (716). The optimized conditions, reaction of 1.2 equivalents of 3-bromo-4-lithiopyridine (1238) with M-benzylindole-2,3-dicarboxylic anhydride (852) at —96°C, led regioselectively to the 2-acylindole-3-carboxylic acid 1233 in 42% yield. Compound 1233 was converted to the corresponding amide 1239 by treatment with oxalyl chloride, followed by diethylamine. The ketone 1239 was reduced to the corresponding alcohol 1240 by reaction with sodium borohydride. Reaction of the alcohol 1240 with f-butyllithium led to the desired 6-benzylellipticine quinone (1241), along with a debrominated alcohol 1242, in 40% and 19% yield, respectively. 6-Benzylellipticine quinone (1241) was transformed to 6-benzylellipticine (1243) in 38% yield by treatment with methyllithium, then hydroiodic acid, followed... 

Apart from reactions with sodium borohydride, which is frequently used in water or water-alcohol mixtures to selectively reduce ketones or aldehydes, water is rarely used in reductions because of chemical incompatibility with most reducing agents. Nevertheless, water was shown to influence these types of reactions. 

Attempts were made to reduce any aldehyde and ketone function with sodium borohydride. A 1.5-gram sample was weighed into a 100-ml. reaction flask and suspended in 10 ml. of methanol. A solution of 0.3 gram of sodium borohydride in 25 ml. of 0.1 IV sodium hydroxide was added to the sample over a period of 15 minutes. The mixture was refluxed under nitrogen for 6 hours, filtered, and washed thoroughly with water. The amount of aldehyde and ketone was estimated by the decrease in the 5.8 micron peak in the infrared spectrum of the treated sample as compared with the untreated sample. 

Once again, it is important to realize that cyclization to a coumaranone is a feasible alternative reaction. Indeed, in the above example treatment of the initial ketone (589) with sodium hydroxide instead of diethylaniline gave 2,2-diethyl-5-methylcoumaran-3-one together with hydrolyzed but uncyclized ketone (590). 

If the ketone has a methyl group containing chlorine, the reaction can take the other possible pathway, and the chlorofluoromcthane can hydrolyze, because of the variable stability of the chlorine-substituted methyl carbanions in alkali. l-Chloroheptafluorobutan-2-one (8), 1,1-di-chlorohexafluorobutan-2-one (9), and l,l,l-trichloropentafluorobutan-2-one (10) on reaction with sodium hydroxide give sodium pentafluoropropanoate (11).174... 

The reaction of 24.and HC1 yields alkylchloroborane triphenyl phosphane complexes 28, which can be converted with olefins in the presence of benzyliodide 25 (15). The dialkylchloroboranes 32 thus formed can be transformed into ketones 33, with sodium methylate and then the DCME-technique of H.C. Brown (16). 

A better synthesis of a-(l,2-dithiol-3-ylidene)ketones from thio-pyran-4-thiones consists in the reaction with sodium hydroxide in dimethylformamide (DMF), followed by ferricyanide oxidation (Eq. 3).11... 

A similar reaction with sodium benzcnethiolatc results in a-phcnylthio ketones. Example ... 

In order to study the factors determining the regioselectivity of sodium borohydride reduction of a, -unsaturated ketones, reactions with 3-methylcyclohexenone, carvone and cholestenone were carried out in 2-propanol, diglyme, triglyme or pyridine. Mixtures of 1,2- and 1,4-reduction products were obtained in the alcoholic and ether solvents, whereas pure 1,4-reduction was observed in pyridine. Addition of triethylamine to NaBH4 in diglyme led to formation of triethylamine borine, EtsN BHs. Similarly, with pyridine, pyridine borine could be isolated, leading to exclusive 1,4-reductions. 

The first report on the reduction of a carbonyl substituted cyclopropane was published in 1949. Reactions of methyl cyclopropyl ketone (131) with sodium in liquid ammonia in the presence of ammonium sulfate yielded instead of the expected methyl cyclopropylcarbinol (132) only a mixture of 2-pentanone (133) and 2-pentanol (134). 

In reductive acylation and dimerization, the cathode is often superior to dissolving metal or radical anions reductants. So a, j6-unsaturated ketones or esters can be acylated in high yield to 1,4-dicarbonyl compounds at the mercury cathode [39], but the corresponding reaction with sodium in tetrahydrofuran (THE) fails [40]. On the other hand, reductive acylation of double bonds becomes possible in high yield, when vitamin Bj2 is used as mediator [41]. Here cobalt-alkyl complexes play a decisive role as intermediates. 

Transannular cyclization of ketoalkenes was first reported in 1965. Treatment of the conformationally restricted ketone (104) with sodium in moist ether gave the alcohol (105 equation 127). Similarly the ketoalkene (106) transannulated in 73% yield by exposure to sodium in refluxing propanol (equation 128). Conformational restriction is not a prerequisite for transannular reaction thus the caryophyllene (107) undergoes cyclization to the alcohol (108) with lithium in liquid ammonia (equation 129). Transannulation across a nine-membered ring has also been observed upon treatment of ketone (109 equation 130) with samarium diiodide, via cyclization of the ketoalkene (110). Of more practical importance, the electrochemical transannulation of the cyclooct-4-en-l-one gives the bicyclo[3.3.0]octanol (111 equation 131). ... 

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