Alkali fusion oxidative

Alkali fusion of oleic acid at about 350°C ia the Varrentrapp reaction causes double-bond isomerization to a conjugated system with the carboxylate group followed by oxidative cleavage to form palmitic acid (75). In contrast, alkaU fusion of riciaoleic acid is the commercial route to sebacic acid [111 -20-6] ... 

Alkali fusion of the metabolite furnished p-hydroxybenzoic acid in good yield as the only isolable product. Vigorous nitric acid oxidation of M gave a high yield of picric acid. Both degradation products must have arisen from the same site, which can be represented by part structure V. While positions 3 and 5 are probably unsubstituted, the vigorous nature of the degradations allows that those at 2 and 6 could bear carbon atoms. 

In 1904 Bally obtained a bluish violet solid by alkali fusion of benzanthrone at approximately 220 °C. Two isomeric compounds were isolated by vatting the reaction mixture and filtering off a sparingly soluble sodium salt. Oxidation of the filtrate gave a blue vat dye, violanthrone (6.75 Cl Vat Blue 20), as the main component. The less soluble residue similarly afforded a violet product, isoviolanthrone (6.76 Cl Vat Violet 10). The formation of isoviolanthrone can be suppressed by carrying out the fusion in a solvent such as naphthalene or a polyethylene glycol in the presence of sodium acetate and sodium nitrite. Dyes of this type are often referred to as dibenzanthrones. 

The pigment form [16] is obtained from the leuco form, which in turn is prepared by oxidation with alkali fusion, followed by treatment with sodium hydro-gensulfite solution or sodium dithionite (vatting). 

Dihydroxyindole and 5,6-dihydroxyindole-2-carboxylic acid were shown to form after the red pigment stage that occurred during the conversion of DOPA into a melanin, by Raper, who isolated these compounds as their dimethyl ethers.72 The presence of 5,6-dihydroxyindoles in solutions of DOPA, dopamine, and noradrenaline which are undergoing oxidation has subsequently been confirmed by paper and thin-layer chromatography.118,120,222 5,6-Dihydroxyin-dole and 5,6-dihydroxyindole-2-carboxylic acid have recently been isolated from the alkali fusion products of sepiomelanin, indicating... 

Other preliminary experiments on alkali lignin included oxidations by barium peroxide and alkali (5, 6), alkali fusion, and alkali fusions in the presence of calcium peroxide, sodium borate perhydrate, and monopersulfate compound. Ether extractives and water extractives were examined, but in all cases too many of the oxidation products obtained were new and unidentifiable, and it was impossible to evaluate the experiments adequately with the available techniques. Vanillic acid appeared to be the chief oxidation product under conditions which did not demethylate further or destroy the aromatic nature of the oxidation products. Some oxidation conditions yielded p-hydroxybenzyl moieties as products, and some gave no trace of these products whatever. More detailed studies of the ether-insoluble, water-soluble components of the several oxidation mixtures were postponed until adequate procedures were developed for analytical isolation and identification. 

Occasionally in the synthesis of phenols by this route oxidation products are formed. A particular example is provided by the alkali fusion of sodium anthraquinone-2-sulphonate during which a second hydroxyl group is introduced into the 1-position, forming the dyestuff alizarin (1) (cognate preparation in Expt 6.99). In the procedure described the oxidation step is promoted by the deliberate introduction of potassium chlorate as an oxidant. 

The presence of an ethylidene group in echitamine chloride was also demonstrated by oxidation with periodic acid, which was reported to give acetaldehyde and indole-3-acetaldehyde (78). Alkali fusion and selenium dehydrogenation experiments gave inconclusive results, but the basic fractions were suspected to contain derivatives of jS-carboline (77, 78). Oxidation of echitamine with alkaline potassium permanganate afforded a low-melting base, which was considered to be Nb-methyl-tryptamine (80). 

Alizarin (1,2-dihydroxyanthraquinone) is formed by alkali fusion of sodium anthraquinone-2-sulfonate ( silver salt ). The reaction is rather remarkable in that not only is the sulfo group replaced by hydroxyl, but a second hydroxyl is also introduced. The presence of an oxidizing agent has a favorable effect on the reaction. 

The sulfite formed can exert a reducing action when easily reducible groups are present. For this reason, alkali fusion of nitrosulfonic acids rarely works well. Sometimes this redudng action can be counteracted, especially in the anthra-quinone series, by the addition of an oxidizing agent or an all ne earth hydroxide in the latter case, the sulfite is precipitated as an insoluble salt and thus rendered harmless. 

Dihydroxybenzene is prepared industrially by the alkali fusion of benzene-1,3-disulfonic acid. 1,4-Dihydroxybenzene is prepared in large quantities for use as a photographic developer, one process being by the oxidation of aniline with manganese dioxide [manganese(IV) oxide] in sulfuric acid to give benzo-l,4-quinone, which is then reduced to 1,4-dihydroxybenzene (hydroquinone, quinol). 

Methods available for the dissolution of ruthenium metal involve alkali fusion under oxidizing conditions. The absence of complete experimental details makes repetition of these methods difficult. The following procedure is a modification of those of Antony and Lucchesi and of Charonnat and, excluding the period of overnight evaporation, takes about 3 hours. The precise stoichiometry of the fused-salt reaction is not known. All procedures must be carried out in a fume hood since chlorine and some ruthenium tetraoxide are produced. 

The NMR-spectrum of macrorine shows, besides an iV -methyl group, only aromatically linked protons and the IR-spectrum contains only aromatic bands. Macrorine is stable to zinc dust distillation and to alkali fusion. With hydrogen and platinic oxide it gives a tetrahydro derivative which contains an NH group and has a UV-spectrum resembling that of l,2,3,4-tetrahydroquinoline-2-carboxyamide NMR-spectroscopy also suggests a 1,2,3,4-tetrahydroquinoline structure. 

Hofmann degradation of the crystalline mesembrine methiodide afforded a definite desmethylmesembrine but further degradation failed (11). Alkali fusion, degradation by ozone, and selenium dehydrogenation (6) were also without success. Oxidation with potassium permanganate produced 3,4-dimethoxyphenylglyoxylic acid and 3,4-dimethoxy-benzoic acid (7). 

Graebe and Kraft showed that the methyl group of a methylated phenol can be transformed into carboxyl by a process describable as an oxidative alkali fusion, the oxidant being lead dioxide. They applied the method successfully to the three cresols, the three toluic acids, 2,4-dimethylphenol, and o-cresotinic acid (1, available from Eastman). A preparative procedure for the conversion of (1) into 2-hydroxyiso-phthalic acid (2) is as follows. A mush of 240 g. of potassium hydroxide pellets and... 

Historically, several processes have been developed to an industrial scale to produce phenol, including (i) sulfonation of benzene and alkali fusion of the benzene sulfonate (ii) chlorination of benzene and hydrolysis of chlorobenzene (iii) the cumene process (Section 13.2) (iv) toluene oxidation to benzoic add and subsequent oxidative decarboxylation of the latter to phenol and (v) dehydrogenation of cyclohexanol-cyclohexanone mixtures. Today, however, only the cumene process and the toluene oxidation are still run on an industrial scale, all the other processes having been given up due to economic reasons or environmental problems. 

Fusion with alkali in the presence of air (oxygen) often accomplishes oxidations impossible to obtain otherwise. For instance, the formalion of oxyacids from substituted phenols by direct oxidation of side chmns is difficult of accomplishment because of the much greater susceptibility of the hydroxyl group to attack and consequent tendency for the breakdown of the molecule. Alkali fusion accomplishes the desired reaction but with poor 3rields. Xylenols yield the corresponding mono- and dibasic acids by... 

The mixture of the two methine bases when treated with alcoholic alkali yielded a nitrogen-free compound which produced a tricarboxylic acid (m.p. 178°) on oxidation. For a number of years work was directed towards the identification of the tricarboxylic acid by degradative studies and by syntheses (50, 51, 52). Alkali fusion resulted in p-hydroxybenzoic acid, and on this basis it was concluded that the tricarboxylic acid must be one of the three isomeric acids LII, LIII, and LIV. All three were synthesized (50, 51, 52) by an Ullmann condensation of the appropriate compounds, and LIV (52) proved to be identical in all respects with that obtained from methylated isochondodendrine by degradation. Iso-chondodendrine was then assigned the structure LV or LVI. 

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