Aldehydes silver® oxide

Oxidation of a-amino-acids with silver(ii) picolinate gives almost quantitative yields of nor-aldehydes silver oxide causes further oxidation to the nor-acid. The possibility is suggested of the simultaneous operation of a radical mechanism in solution and a two-electron shift process at the solid silver salt surface. Aryl alkanes and aryl alkanols are oxidized by silver(ii) picolinate to aldehydes and ketones, a-Aminoketones are dehydrogenated by mercury(ii) salts to ketones iminium ions, such as (139), are postulated as intermediates (Scheme 58). 

Tollens reagent An ammoniacal solution of silver oxide which is used as a lest for aldehydes, which, unlike ketones, cause the deposition of a silver mirror. 

Isothiazole-3-carboxylic acid and its 4-bromo derivative have been obtained by oxidation of the corresponding aldehydes with silver oxide. They form acid chlorides, esters, and amides. The amides may be dehydrated to give the corresponding nitriles. ... 

I Oxidation of a primary alcohol or an aldehyde yields a carboxylic acid (Sections 17.7 and 19.3). Primary alcohols are often oxidized with C1O3 in aqueous acid, and aldehydes are oxidized with either acidic Cr03 or basic silver oxide (Tollens reagent). 

The biogenetic scheme for endiandric acids also predicts the plausible existence in nature of endiandric acids E (5), F (6), and G (7). Even though they are still undiscovered, their synthesis has been achieved (Scheme 6). For endiandric acids E and F, key intermediate 24 is converted, by conventional means, to aldehyde 35 via intermediate 34. Oxidation of 35 with silver oxide in the presence of sodium hydroxide results in the formation of endiandric acid E (5) in 90 % yield, whereas elaboration of the exo side chain by standard olefination (85 % yield) and alkaline hydrolysis (90 % yield) furnishes endiandric acid F (6). The construction of the remaining compound, endiandric acid G (7), commences with the methyl ester of endiandric acid D (36) and proceeds by partial reduction to the corresponding aldehyde, followed by olefination and hydrolysis with aqueous base as shown in Scheme 6. 

To identify the specific aldehyde that is actually involved in the light-emitting reaction of living luminous bacteria, Shimomura et al. (1974a) extracted and purified the aldehyde from 40 g each of the bacterial cells of P. phosphoreum, Achromobacter (Vibrio or Photobacterium) fischeri, and an aldehydeless mutant of A. fischeri. The aldehyde fractions were purified, and then oxidized with Tollens reagent (silver oxide dissolved in ammonia) to convert the CHO group into the COOH group. Then the acids obtained were analyzed by mass spectrometry. The results indicated that P. phosphoreum had contained a mixture of aldehydes dodecanal (5%), tetradecanal (63%) and hexadecanal (30%), as shown in Table 2.2. Thus, tetradecanal was clearly predominant in... 

L-dihydroxy-succinic acid (L(dexiro)-tartaric acid, CXIII). This result establishes the position of the double bond between C4 and C5 and demonstrates that C4 carries only one hydrogen atom while C5 has attached to it the enolic hydroxyl group. Treatment of the enol CXI with ethereal diazomethane gives 5-methyl-A4-D-glucosaccharo-3,6-lactone methyl ester (CXIY) which upon further methylation with silver oxide and methyl iodide yields 2,5-dimethyl-A4-D-glucosaccharo-3,6-lactone methyl ester (CXV). When the latter is subjected to ozonolysis there is formed oxalic acid and 3-methyl-L-threuronic acid (CXVI). Oxidation of this aldehydic acid (CXYI) with bromine gives rise to a monomethyl derivative (CXVII) of L-ilireo-dihydroxy-succinic acid. 

Oxidation of one molar proportion with sodium pieriodate produces two equivalents of formic acid, in accordance with the existence of hydroxyl groups attached to four contiguous carbon atoms. This oxidation (and also that carried out with lead tetraacetate) gives an aldehyde, whose semicar-bazone has an analysis corresponding to that of the semicarbazone of an ethyl formyl-methyl-furoate (XII). By oxidation of aldehyde XII with silver oxide in alkaline solution, 2-methyl-3,4-furandicarboxylic acid (XIV) was obtained this was identical with the compound described by Alder and Rickert.20 The identity was confirmed by preparation of the respective dianilides. The acid XIV has also been prepared by the reaction between the sodium salt of ethyl acetoacetate and ethyl bromopyruvate.9... 

The sequence of reactions leading to compound 83 by an elimination that liberates the aldehyde 82, which is immediately reduced to 83, is depicted. This result also explains the formation of 43 by Purdie-Irvine methylations of 4 (Ref. 29) and 33 (Ref. 24) in both, moist silver oxide is the base, and it initiates elimination followed... 

Temporary protection of the aldehyde function and reduction with aluminum hydride gave ( )-3-epigeissoschizal (275), from which silver oxide oxidation, followed by esterification, resulted in methyl ( )-epigeissoschizoate (277). 

The silver oxide oxidation of aldehydes to carboxylic acids is aided by the addition of benzyltriethylammonium chloride the active agent is thought to be TEBA-Ag(OH) [16]. 

Tollen s aldehyde test analychem A test that uses an ammonlacal solution of silver oxides to test for aldehydes and ketones. tal anz al da.hTd. test) tolnaftate org chem C19H17NOS An agricultural fungicide It Is also used medically as an antifungal agent. tol naf.tat ... 

Effective conditions for oxidation of aldehydes to carboxylic acids with KMn04 involve use of t-butanol and an aqueous NaH2PC>4 buffer as the reaction medium.173 Buffered sodium chlorite is also a convenient oxidant.174 175 An older reagent for carrying out the aldehyde — carboxylic acid oxidation is silver oxide. 

Monosaccharides react with a variety of 1,3-dicarbonyl compounds in the presence of zinc chloride in ethanolic or aqueous solution to yield substituted furans (Scheme 69) (56MI31200). The reaction of ethyl acetoacetate with D-glucose and D-mannose yielded the trisubstituted furan (252) in 20% yield, while D-fructose under similar conditions yielded (253 7%). These products have been used for the synthesis of dehydromuscarones (63HCA1259). Oxidation of the tetrahydroxybutyl side chains with lead tetraacetate gives the aldehyde, which can be converted to the corresponding acid with alkaline silver oxide. 

Dimethylcarbodihydrazide (280) reacts with aldehydes to afford 1,5-dimethyltetrahydro-l,2,4,5-tetrazin-6-ones (281), which can be oxidized by silver oxide, potassium ferricyanide or lead dioxide to yield radicals (282) related to the verdazyls these can be transformed into tetrahydro-l,2,4,5-tetrazines (283) by hydrogenation over palladium (80AG766). 

Aldehydes are oxidized easily by moist silver oxide or by potassium permanganate solution to the corresponding acids. The mechanism of the permanganate oxidation has some resemblance to the chromic acid oxidation of alcohols (Section 15-6B) ... 

To further purify the alcohol the above product is shaken with finely divided silver oxide. This oxidises any aldehyde present to acetic acid. Caustic soda is added to bind the acid, and the alcohol distilled, using a good column (see p. 22). The portion passing over at constant temperature is then treated with calcium turnings in the same way as methyl alcohol (see above). The anhydrous alcohol is very hygroscopic, and must not be exposed to air. 

The most widely used routes to benzo[ >]thiophene-2-carboxylic acids are (a) successive lithiation and carbonation of the parent benzo[ >]thiophene,42,76 90 98,183,477, 481>487,521,685-687 (ft) oxidation of the corresponding aldehyde,90,91,106,189 424, 477,640 (c) hypohalite oxidation of the corresponding methyl ketone,82 °8,189,424 and (d) cyclization reactions (Section IV,D, and E). Acids prepared by these routes are listed in Table XV. Oxidation of aldehydes usually proceeds almost quantitatively with moist silver oxide,90,91,105, 189,424 hut potassium permanganate is satisfactory.477, 640... 

Methanolysis of penta-0-benzoyl-5-bromo-/ -D-glucopyranose, using silver oxide and methanol, gives a complex set of products, but hydrolysis in the presence of this solid affords the 5-hydroxy analog 128 which, in aqueous media, equilibrates with the 5-ulose 129 this loses benzoic acid, and the resulting aldehyde recyclizes, to afford 2,3,4,6-tetra-0-benzoyl-5-hydroxy-/ -D-glucose (130) (see Scheme 21).26... 

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