Methane from sodium acetate

The reaction lesembles the fonnation of methane from sodium acetate when heated with soda-lime. 

Methane from Sodium Acetate.— Acetic acid, as we shall understand before we have proceeded far in our study, is a compound related to methane. When the sodium salt of this acid, i.e., sodium acetate, is heated it loses carbon dioxide, CO2, and methane is produced. In practice this heating is carried out in the presence of an alkali, e.g., calcium or sodium hydroxide, which absorbs the carbon dioxide, and in this way assists in the reaction. In order that we may not be troubled by the presence of water, dry materials are used, the sodium acetate being fused to obtain it free of water. When this dry sodium acetate is heated with a mixture of sodium and calcium hydroxides, known as soda-lime, a gas is produced which may be collected over water. The gas so made is methane and is identical with that found naturally as marsh gas and as a constituent of fire damp, natural gas, coal gas and petroleum. 

Amongst the earliest experiments carried out with a view to the quantitative determination of the limits of inflammability of combustible gases were those of Davy with fire damp, wfliich is mainly methane, CH4. Owing to the importance of this gas m connection with gob fires and explosions in coal mines, several other workers have also investigated it. The value of the results, however, is restricted by the fact that firedamp, like most natural products, is subject to very considerable variation in composition.3 Even Davy recognised that it was not pure methane indeed, perfectly pure methane is not easy to prepare in quantity. The gas, as obtained from sodium acetate, may contain as much as 8 per cent, of hydrogen, as well as ethylene.4 No doubt this variation m composition is one contributory cause of the very varied results listed in the table on p. 93. 

Acetic acid is used as a solvent for resins and oil. Its salts are as important as the acid itself. For example, methane is produced from sodium acetate and acetone is produced from calcium acetate. Aluminium acetate is used in dyeing as a mordant, for proofing paper and fabrics and in pharmacy as an antiseptic and astringent. Cellulose acetate, an acetic acid derivative, is used in lacquers, shatter- proof glass, varnishes and as a fiber. Acetic acid is also the starting material in the production of rubber. 

Preparation of Bisacodyl 5 grams of (4,4 -dihydroxy-diphenyl)-(pyridyl-2)-methane are heated with 5 grams of anhydrous sodium acetate and 20 cc of acetic anhydride for three hours over a boiling waterbath. The cooled reaction mixture is poured into water, whereby after a while a colorless substance precipitates, which Is filtered off with suction, washed with water and recrystallized from aqueous ethanol. Colorless bright crystals, MP 138°C are obtained. 

Murofushi et al. (8) protected the 16,17 double bond of GA5 methyl ester by forming the epoxide with metachloroperben-zoic acid. After catalytic reduction of the 2,3 double bond they restored the exomethylene group by treatment with a mixture of sodium iodide, sodium acetate and zinc and hydrolyzed the methyl ester to obtain [2,3-3h2]GA2o Yakota et al. (81) prepared [2,3-3h2]GASelective catalytic reduction of the 3-methane-... 

Pure methane, propane, and butane can be easily found from local chemicals suppliers, if the commercial mixtures traded (natural gas, commercial propane, and commercial butane) are not good for some laboratory work. For small lab demonstrations they may also be obtained in situ e.g., methane may be easily produced by means of Al C3(s)+6H20(l) = 3CH (g) + 2Al203(s), or by heating a 50/50 mix of anhydrous sodium acetate and sodium hydroxide, NaOH(s) + NaC H O fs) = CH (g)+Na2C03(s), as did his discoverer, the American Mathews, in 1899. 

Simple transition metal mercaptides, such as Ni(SR)2 or Hg(SR)2, are usually prepared by reactions not involving the thiolate anion as a nucleophile . Occasional use is made of thiolates, for instance in the preparation of chromium(iii) methanethiolate, where sodium methane-thiolate was reacted with chromium chloride in excess of dimethyl disulphide under dry nitrogen and irradiated to yield the desired product, which can also be prepared by other photochemical methods . Cobalt thiolates, [Co(SR)2]n, prepared from cobalt acetate in methanol... 

Preparation. In the laboratory methane can be prepared by hydrolysis of aluminum carbide (Al Cj) or to a lesser extent beryllium carbide (Be C) or by decomposing sodium acetate with sodium hydroxide. Carbon reacts with pure hydrogen to yield methane at temperatures above 1100°C but the reaction becomes noticeable only above 1500°C. In addition, a catalyst must be used to prevent the formation of acetylene. Commercially methane is only obtained from natural gas (see Section 17.5) or from fermentation of cellulose or sewage sludges. 

To 6a-fluoro-16a-hydroxy-hydrocortisone 21-acetate, described by Mills et al, J. Am. Chem. Soc., volume 81, pages 1264 to 1265, March 5, 1959, there was added acetic anhydride in dry pyridine. The reaction mixture was left at room temperature overnight and was then poured with stirring into ice water. The resulting precipitate was filtered, washed with water and crystallized from acetone-hexane to give 6a-fluoro-16a-hydroxy-hydrocortisone-16a,21-diacetate. This was reacted with methane-sulfonyl chloride in dimethyl formamide in the presence of pyridine at 80°C for 1 hour. The mixture was cooled, diluted with water and extracted with ethyl acetate. The extract was washed with water, dried over anhydrous sodium sulfate and the ethyl acetate was evaporated. By recrystallization of the residue from acetone-hexane there was obtained 6a-fluoro-A <" -pregnadiene-16o ,17a,21-triol-3,20-dione 16a,21 diacetate. 

Of the synthetic reactions of the alkyl halides that with potassium cyanide, which enabled H. Kolbe to synthesise acetic acid from a methane derivative, has already been mentioned (cf. the preparations on pp. 137 and 254). Of the simpler syntheses that of Wiirtz may be mentioned here. Metallic sodium removes the halogen from two molecules and the two radicles combine. Thus, in the simplest case, ethane is formed from methyl bromide ... 

Mercury bis-a-acetyl-a-isopropyl or Mercury-bis-aceto-di-methyl-methane, [CHgCO.CMeg—JgHg.—Mercuric dimethyl aceto-acetate is heated in a vacuum at 90 C., when it is found to lose two molecular equivalents of carbon dioxide, which is shown by the loss in weight. The resulting mass is extracted with acetone, and the solvent removed m vacuo, the product isolated melting at 120 C. It is soluble in acetone, alcohol, toluene, or xylene, but only slightly soluble in ether. Mercuric sulphide is split off from it by the action of ammonium sulphide, but no mercuric oxide is formed when sodium hydroxide is added. The compound soon decomposes with the deposition of metallic mercury. 

In the presence of alkoxides chloroform reacts with secondary amines or aziridines to yield a mixture of aminal esters (486), amide acetals (487) and tris(dialkylamino)methanes (488 equation 224). Predominantly aminal esters (489 equation 225) are formed in the reaction of dchloromethyl ether with aziridines and sodium hydioxide. The heterocyclic aminal ester (491 equation 226) was prepared from the perimidine (490) and triethyl orthoformate. ... 

The functional stability of GOD membranes has also been enhanced by coupling with an asymmetric ultrafiltration membrane (Koyama et al., 1980). The GOD-cellulose acetate membrane used was prepared as follows 250 mg cellulose triacetate was dissolved in 5 ml dichloro-methane, the solution was mixed with 0.2 ml 50% glutaraldehyde and 1 ml l,8-diamino-4-amino methyl octane and sprayed onto a glass plate. After three days the membrane was removed from the support and immersed in 1% glutaraldehyde solution for 1 h at 35°C, rinsed with water and exposed for 2-3 h to phosphate buffer, pH 7.7, containing 1 mg/ml GOD. The membrane was then treated with sodium tetraborate, rinsed with water and stored at 4-lO°C until use. It was combined with the ultrafiltration membrane in the following way 20 mg cellulose diacetate was dissolved in 35 g formamide and 45 g acetone and cast on a glass plate. At room temperature the solvents evaporated within a few seconds and a membrane of about 30 pm thickness remained, which was kept in ice water for 1 h before application in the sensor. 

A similar oxidation of olefins with sodium bismuthate in acetic acid at elevated temperature (100°C) leads to a mixture of v/c-diol diacetate and carbonyl compound arising from oxidative cleavage, together with molecular oxygen and carbon dioxide [71KKZ1807]. In the absence of an olefin, sodium bismuthate works destructively on acetic acid to generate molecular oxygen, carbon dioxide, methyl acetate and a trace amount of methane, while the bismuthate is converted to bismuth acetate when the reaction is complete. The proposed mechanism is shown in Scheme 5.6. 

The above structure for the colorless desoxyvomicine fails to offer a satisfactory explanation for the formation of a methiodide by this base, while vomicine fails to react with methyl iodide under similar conditions. Reduction of an acetic acid solution of desoxyvomicine methiodide by sodium amalgam yields the base C23H30O3N2 with two imino-methyl groups (29) (desoxydihydrovomicine and methane result from a similar reduction of desoxydihydrovomicine methiodide (32)). Base C2JH30O3N2 reacts smoothly with methyl iodide, while thermolysis of the derived metho-hydroxide yields trimethylamine. It would seem difficult to find an adequate explanation for the formation of trimethylamine on the present formula for desoxyvomicine. 

Benzene is formed when acetylene is passed through a hot tube, 3C2H2 = CeHe, and when kerosene is heated under pressure (Rittman process, 30). It is also obtained when sodium benzoate is heated with sodium hydroxide. Pure benzene, free from thiophene, was first obtained in this way. Some of the earlier investigations of benzene were carried out with the hydrocarbon prepared from benzoic acid. The reaction is analogous to that by which methane may be prepared from acetic acid... 

Other works on alkane oxidations in trifluoroacetic acid have been also described [56]. Finally, it has been found that heating an aqueous solution of sodium vanadate in the presence of methane, carbon monoxide and air gives rise to the formation of acetic acid, as well as methanol and formaldehyde in smaller amounts [57]. The yield of CH3COOH attains 3700% based on vanadium after 50 h at 100 °C, the total turnover number being 49. The reaction is sensitive to the pH of the solution. For example, the yields of the products decrease noticeably if pH > 5. The reaction apparently involves hydrogen atom abstraction from methane by a radical or radical-hke species which could be generated via the reduction of V(V) with carbon monoxide. 

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