Sodium metals

Insoluble in water, soluble in organic solvents b.p. — 15°C. Prepared by treating 1,4-dibromo-butane with metallic sodium. Reduced to n-butane by hydrogen at 200" C in presence of nickel catalysts. 

Colourless liquid b.p. 69 5 C. Manufactured from propanone by conversion to pinacone and passing its vapour over heated KHSO4. Slowly changes to a rubber-like substance the change is hastened by metallic sodium or peroxides. Used in the manufacture of artificial rubber. 

Toluene-/ sulplionamide is almost insolubb in cold water, but dissolves readily in sodium hydroxide solution (as the sodium derivative) aid is immediately reprecipitated on the addition of strong acids. To show the formation of the sodium derivative, dissolve about o-2 g. of metallic sodium in about 10 ml, of ethanol, cool the solution, and then add it to a solution of 1 g. of the sulphonamide in 20 ml. of cold edianol. On shaking the mixture, fine white crystals of the sodium derivative, CH,C,HjSO,NHNa, rapidly separate, and may be obtained pure by filtering at the pump, and washing firet with a few ml. of ethanol, and then with ether. 

It is readily prepared by the action of metallic sodium on dry ethyl acetate. The reaction, which occurs only in the presence of a trace of ethanol, is complex, but may be considered (in effect) as a condensation of two molecules of ethyl acetate under the influence of sodium ethoxide, the sodium derivative of the enol form being thus obtained. Clearly, only a trace of ethanol is thus initially... 

Mono and Di-iubstitution Derivatives. The enolic sodium derivative of ethyl acetoacetate (E) is prepared by mixing ethanolic solutions of the ester and of sodium ethoxide. It should not be prepared by the direct action of metallic sodium on the ester, as the reaction is slow and the nascent hydrogen evolved reduces some of the ester to ethyl p4iydroxy- butyrate, CH3CH(OH)CHjCOOEt. 

This method, due to Middleton (Analyst, 1935, 6o, 154), has the advantage over Lassaigne s method (pp. 321-326) that the use of metallic sodium is avoided it has the disadvantage, however, that the reagents are not so readily obtained pure, and the method requires rather more time. 

In general the method is more satisfactory with esters of aromatic acids than with esters of aliphatic acids. Esters of alcohols other than methyl and ethyl are best treated by first converting them into methyl esters thus Heat together under reflux i ml. of the higher ester, 5 ml. of methanol and 0-2 g. of sodium methoxide. [In place of the sodium methoxide, it suffices to add o i g. of metallic sodium to the methanol.] After refluxing, distil off the excess of methanol (b.p, 65 ). The residue is then heated under reflux with benzylamine as described above. 

Most nitrocompounds react vigorously with metallic sodium during the tests for elements present (p. 321). 

Chloroform and carbon tetrachloride must not be heated with metallic sodium as an explosive reaction is likely to take place (see footnote, p. 321). 

Safety goggles should always be worn over the eyes when carrying out potentially dangerous operations, e,g. vacuum distillations, distillation of large volumes of inflammable liquids and experiments employing large quantities of metallic sodium. 

Metallic sodium. This metal is employed for the drying of ethers and of saturated and aromatic hydrocarbons. The bulk of the water should first be removed from the liquid or solution by a preliminary drying with anhydrous calcium chloride or magnesium sulphate. Sodium is most effective in the form of fine wire, which is forced directly into the liquid by means of a sodium press (see under Ether, Section II,47,i) a large surface is thus presented to the liquid. It cannot be used for any compound with which it reacts or which is affected by alkalis or is easily subject to reduction (due to the hydrogen evolved during the dehydration), viz., alcohols, acids, esters, organic halides, ketones, aldehydes, and some amines. 

Saturated and aromatic hydrocarbons Ethers Anhydrous calcium chloride anhydrous calcium sulphate metallic sodium phosphorus pentoxide. 

Other sources of hazard arise from the handling of such chemicals as concentrated acids, alkalis, metallic sodium and bromine, and in working with such extremely poisonous substances as sodium and potassium cyanides. The special precautions to be observed will be indicated, where necessary, in the experiments in which the substances are employed, and will also be supplied by the demonstrator. The exercise of obvious precautions and cautious handling will in most cases reduce the danger to almost negligible proportions. Thus, if concentrated sulphuric acid should be accidentally spilled, it should be immediately washed with a liberal quantity of water or of a solution of a mild alkali. 

Acetals are usually liquid they are almost unaffected by alkalis and are not attacked by metallic sodium nor by Fehling s solution. They are identified by reference to the alcohol and aldehyde (or ketone if a ketal) which they yield when hydrolysed in acid solution. Hydrolysis proceeds readily in dilute acid solution e.g., with 3-5 per cent, acid). ... 

Method 1. Place 11 5 g, of clean metallic sodium (compare Section III,7, Note 1), cut into small pieces, into a dry 1 litre round-bottomed fiask fitted with a 25 cm. double surface reflux condenser. Introduce 250 ml. of absolute, but preferably super dry (see Section 11,47, 5) ethyl alcohol all at once. A vigorous reaction ensues if the condenser tends to become flooded with alcohol, cool the flask either by surrounding it with a wet towel or by directing the waste water from the condenser upon... 

It may be mentioned that the condensation in the presence of metallic sodium appears to be partly effected by the metal which displaces atomic hj drogen from the ketone ... 

Metallic sodium is vital in the manufacture of esters and in the preparation of organic compounds. The metal may be used to improve the structure of certain alloys, to descale metal, and to purify molten metals. 

Metallic sodium is priced at about 15 to 20 cents/lb in quantity. Reagent grade (ACS) sodium in January 1990 cost about 35/lb. On a volume basis, it is the cheapest of all metals. 

Group I metals—sodium is the one usually employed—in liquid ammonia as the solvent convert alkynes to trans alkenes The reaction proceeds by a four step sequence in which electron transfer and proton transfer steps alternate... 

Alcoholysis (ester interchange) is performed at atmospheric pressure near the boiling point of methanol in carbon steel equipment. Sodium methoxide [124-41 -4] CH ONa, the catalyst, can be prepared in the same reactor by reaction of methanol and metallic sodium, or it can be purchased in methanol solution. Usage is approximately 0.3—1.0 wt % of the triglyceride. 

Other reactions similar to the aldol addition include the Claisen and Perkin reactions. The Claisen reaction, carried out by combining an aromatic aldehyde and an ester in the presence of metallic sodium, is useful for obtaining a,P-unsaturated esters. 

Electrolytic plant producing metallic sodium and chlorine from molten sodium chlorine. 

The use of alkaU metals for anionic polymerization of diene monomers is primarily of historical interest. A patent disclosure issued in 1911 (16) detailed the use of metallic sodium to polymerize isoprene and other dienes. Independentiy and simultaneously, the use of sodium metal to polymerize butadiene, isoprene, and 2,3-dimethyl-l,3-butadiene was described (17). Interest in alkaU metal-initiated polymerization of 1,3-dienes culminated in the discovery (18) at Firestone Tire and Rubber Co. that polymerization of neat isoprene with lithium dispersion produced high i7j -l,4-polyisoprene, similar in stmcture and properties to Hevea natural mbber (see ELASTOLffiRS,SYNTHETic-POLYisoPRENE Rubber, natural). 

V-Alkylation can also be carried out with the appropriate alkyl haUde or alkyl sulfate. Reaction of aniline with ethylene, in the presence of metallic sodium supported on an inert carrier such as carbon or alumina, at high temperature and pressure yields V/-ethyl- or /V,/V-diethylaniline (11). At pressures below 10 MPa (100 atm), the monosubstituted product predominates. 

Potassium dissolves in Hquid ammonia, but the conversion of a small amount of the metallic potassium to the metallic amide takes several days. By applying the same technique using sodium metal, sodium amide [7782-92-5] NaNH2, a white soHd, can be formed. 

Early Synthesis. Reported by Kolbe in 1859, the synthetic route for preparing the acid was by treating phenol with carbon dioxide in the presence of metallic sodium (6). During this early period, the only practical route for large quantities of sahcyhc acid was the saponification of methyl sahcylate obtained from the leaves of wintergreen or the bark of sweet bitch. The first suitable commercial synthetic process was introduced by Kolbe 15 years later in 1874 and is the route most commonly used in the 1990s. In this process, dry sodium phenate reacts with carbon dioxide under pressure at elevated (180—200°C) temperature (7). There were limitations, however not only was the reaction reversible, but the best possible yield of sahcyhc acid was 50%. An improvement by Schmitt was the control of temperature, and the separation of the reaction into two parts. At lower (120—140°C) temperatures and under pressures of 500—700 kPa (5—7 atm), the absorption of carbon dioxide forms the intermediate phenyl carbonate almost quantitatively (8,9). The sodium phenyl carbonate rearranges predominately to the ortho-isomer. sodium sahcylate (eq. 8). 

Sir Humphry Davy first isolated metallic sodium ia 1807 by the electrolytic decomposition of sodium hydroxide. Later, the metal was produced experimentally by thermal reduction of the hydroxide with iron. In 1855, commercial production was started usiag the DeviUe process, ia which sodium carbonate was reduced with carbon at 1100°C. In 1886 a process for the thermal reduction of sodium hydroxide with carbon was developed. Later sodium was made on a commercial scale by the electrolysis of sodium hydroxide (1,2). The process for the electrolytic decomposition of fused sodium chloride, patented ia 1924 (2,3), has been the preferred process siace iastallation of the first electrolysis cells at Niagara Falls ia 1925. Sodium chloride decomposition is widely used throughout the world (see Sodium compounds). 

Naphthalene sodium prepared in dimethyl ether or another appropriate solvent, or metallic sodium dissolved in Hquid ammonia or dimethyl sulfoxide, is used to treat polyfluorocarbon and other resins to promote adhesion (138—140). Sodium, usually in dispersed form, is used to desulfurize a variety of hydrocarbon stocks (141). The process is most useful for removal of small amounts of sulfur remaining after hydrodesulfurization. 

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