Sodium amide, solution

Sodium Pbenylethynetellurolate5 An apparatus suitable for work with liquid ammonia under a nitrogen atmosphere is set up. A 500-m/flask is charged with 250 ml of liquid ammonia freshly distilled from sodium. In the liquid ammonia are dissolved 1.15 g (0.05 mol) of sodium, a catalytic amount of iron(III) nitrate is added, and 5.1 g (0,05 mol) of phenylacetylenc are added dropwise over 0.5 h to the sodium amide solution. The mixture is allowed to stand for 40 min and then 6.4 g (0.05 mol) of finely powdered tellurium arc added to the sodium acetylide solution. The ammonia is evaporated and the residue of sodium phenylethyne-tellurolate can be dissolved in an appropriate solvent for further reactions. 

Methyl Phenylethynyl Tellurium1 An apparatus suitable for work with liquid ammonia is set up. Sodium amide is prepared in a 1 -l flask by adding 6.0 g (0.26 mol) of sodium to 250 ml of liquid ammonia, than 25 g (0.25 mol) of phenylacetylene are added dropwise. 30 g (0.24 mol) of tellurium powder are added over 20 min in small portions to the well-stirred sodium amide solution. 36 g (0.25 mol) of methyl iodide are added dropwise over 10 min to the tellurolate solution. The ammonia is then evaporated, the residue is extracted with diethyl ether, the extract is washed with water and the organic phase dried with anhydrous magnesium sulfate. The ether is distilled off and the residue fractionally distilleed under vacuum yield 28 g (48%) b.p. 122-12472 torr (0,267 kPa). 

Dibenzylidene-l,3-ditelluretane1- 3 Under an inert atmosphere, 1.15 g (50 mmol) of sodium are dissolved in 250 ml of liquid ammonia (freshly distilled from sodium). A small amount of iron(III) nitrate is added to the ammonia solution and then 5.1 g (50 mmol) of phenylacetylene are added dropwise to the stirred sodium amide solution over 30 min. The mixture is allowed to stand for 30 min, 6.4 g (50 mmol) of finely powdered tellurium are added, and the ammonia is evaporated from the mixture under protection against atmospheric moisture. Residual liquids are evaporated under vacuum. The residue (sodium phenylethyneteUuiolate) is dissolved in 50 ml of absolute dimethyl sulfoxide and the solution is cooled to 0°. Under continuous cooling, 25 ml of a 2 molar solution of hydrogen chloride in diethyl ether is added slowly. The precipitate is filtered off, washed with water, chloroform, and then recrystallized from dimethylformamide to give the trans-isomer yield 4.3 g (38%) m.p. 270-275°. 

By analogy, ammonium salts should behave as acids in liquid ammonia, since they produce the cation NH4 (the solvo-cation ), and soluble inorganic amides (for example KNHj, ionic) should act as bases. This idea is borne out by experiment ammonium salts in liquid ammonia react with certain metals and hydrogen is given off. The neutralisation of an ionic amide solution by a solution of an ammonium salt in liquid ammonia can be carried out and followed by an indicator or by the change in the potential of an electrode, just like the reaction of sodium hydroxide with hydrochloric acid in water. The only notable difference is that the salt formed in liquid ammonia is usually insoluble and therefore precipitates. 

This reaction also occurs slowly when sodium is dissolved in liquid ammonia initially a deep blue solution is formed which then decomposes giving hydrogen and sodium amide. 

When the sulphon-dichloro-amide is gently boiled with sodium hydroxide solution, the reverse change occurs, and the chloro sodio-amide crystallises out at a suitable concentration ... 

The evolution of nitrogen is not always entirely satisfactory as a test owing to the possible evolution of gaseous decomposition products of nitrous acid itself. The test may be performed as follows. To i ml. of chilled concentrated sodium nitrite solution add i ml. of dilute acetic acid. Allow any preliminary evolution of gas to subside, and then add the mixed solution to a cold aqueous solution (or suspension) of the amide note the brisk effervescence. 

Aliphatic amides may be hydrolysed by boiling with 10 per cent, sodium hydroxide solution to the corresponding acid (as the sodium salt) the alkahne solution should be acidified with dilute sulphuric acid any water-soluble acid may then be distilled from the solution. Alternatively, hydrolysis may be eflfected with 10-20 per cent, sulphuric acid. The resulting ahphatic acid (usually a liquid) may be characterised as detailed in Section 111,85. 

Warm a solution of 0 5 g. of the nitrile in 2 ml. of concentrated sulphuric acid to 80-90° and allow the solution to stand for 5 minutes. Cool under the tap and pour the sulphuric acid solution into 20 ml. of cold water. Filter off the precipitated solid and stir it with 5 ml. of cold 5 per cent, sodium hydroxide solution. Collect the insoluble crude amide and recrystallise it from dilute alcohol. 

By treatment of an amide with sodium hypobromite or sodium hypochlorite solution (or with the halogen and alkali), the amine of one less carbon atom is produced, the net result being the elimination of the carbonyl group. An example is ... 

Aromatic nitriles are generally liquids or low melting point solids, and usually have characteristic odours. They give no ammonia with aqueous sodium hydroxide solution in the cold, are hydrolysed by boiling aqueous alkali but more slowly than primary amides ... 

Hydrolysis may be effected with 10-20 per cent, sodium hydroxide solution (see p-Tolunitrile and Benzonitrile in Section IV,66) or with 10 per cent, methyl alcoholic sodium hydroxide. For diflScult cases, e.g., a.-Naphthoniirile (Section IV,163), a mixture of 50 per cent, sulphuric acid and glacial acetic acid may be used. In alkahne hydrolysis the boiling is continued until no more ammonia is evolved. In acid hydro-lysis 2-3 hours boiling is usually sufficient the reaction product is poured into water, and the organic acid is separated from any unchanged nitrile or from amide by means of sodium carbonate solution. The resulting acid is identified as detailed in Section IV,175. 

It is conveniently prepared in the laboratory by the interaction of sulphanil-amide and guanidine (from guanidine nitrate and sodium methoxide solution) the resulting guanidine salt of sulphanilamlde decomposes upon heating at 150-160° into sulphaguanidine and ammonia ... 

Amides. Simple (primary) amides (RCONH,) when warmed with dilute sodium hydroxide solution give ammonia readily, together with the salt of the corresponding acid ... 

Nitriles. These are best hydrolysed by boiling either with 30-40 per cent, sodium hydroxide solution or with 50-70 per cent, sulphuric acid during several hours, but the reaction takes place less readily than for primary amides. Indeed the latter are intermediate products in the hydrolysis ... 

Hydrolysis of a substituted amide. A. With 10 per cent, sulphuric acid. Reflux 1 g. of the compound (e.g., acetanilide) with 20 ml. of 10 per cent, sulphuric acid for 1-2 hours. Distil the reaction mixture and collect 10 ml. of distillate this will contain any volatile organic acids which may be present. Cool the residue, render it alkaline with 20 per cent, sodium hydroxide solution, cool, and extract with ether. Distil off the ether and examine the ether-soluble residue for an amine. 

A suspension of 0.40 mol of sodium amide in 300 ml of liquid ammonia was prepared as described in Chapter II, Exp. 11. To the suspension was added with swirling a mixture of 0.25 mol of CHgCeC-S-Ph (see Chapter IV, Exp. 14) and 40 ml of THE in about 2 min (note 1). Swirling was continued after the addition. Three minutes later (note 1) the stopper with glass tube was placed on the flask. The brown solution was forced through the glass tube and the plastic tube, connected to it under 400 g of finely crushed ice, which was contained in a 3-1 conical flask (see Chapter I, Fig. 3, and accompanying description of this operation). The flask was placed for... 

The formation of the above anions ("enolate type) depend on equilibria between the carbon compounds, the base, and the solvent. To ensure a substantial concentration of the anionic synthons in solution the pA" of both the conjugated acid of the base and of the solvent must be higher than the pAT -value of the carbon compound. Alkali hydroxides in water (p/T, 16), alkoxides in the corresponding alcohols (pAT, 20), sodium amide in liquid ammonia (pATj 35), dimsyl sodium in dimethyl sulfoxide (pAT, = 35), sodium hydride, lithium amides, or lithium alkyls in ether or hydrocarbon solvents (pAT, > 40) are common combinations used in synthesis. Sometimes the bases (e.g. methoxides, amides, lithium alkyls) react as nucleophiles, in other words they do not abstract a proton, but their anion undergoes addition and substitution reactions with the carbon compound. If such is the case, sterically hindered bases are employed. A few examples are given below (H.O. House, 1972 I. Kuwajima, 1976). 

Terminal alkynes are only reduced in the presence of proton donors, e.g. ammonium sulfate, because the acetylide anion does not take up further electrons. If, however, an internal C—C triple bond is to be hydrogenated without any reduction of terminal, it is advisable to add sodium amide to the alkyne solution Hrst. On catalytic hydrogenation the less hindered triple bonds are reduced first (N.A. Dobson, 1955, 1961). 

Solutions of sodium acetylide (HC=CNa) may be prepared by adding sodium amide (NaNH2) to acetylene m liquid ammonia as the solvent Terminal alkynes react similarly to give species of the type RC=CNa... 

Other options for the purification of CA include dissolution in hot water, aqueous ammonia, aqueous formaldehyde, or hot dimethylformamide followed by filtration to remove most of the impurities. The CA is recoverable by cooling the aqueous solution (84), acidifying the ammonium hydroxide solution (85), or cooling the dimethylform amide solution with further precipitation of CA by addition of carbon tetrachloride (86). Sodium hydroxide addition precipitates monosodium cyanurate from the formaldehyde solution (87). 

In some cases acid amide formation was observed on attempted deprotonation at oxaziridine ring carbon. 2-r-Butyl-3-(4 -nitrophenyl)oxaziridine (67) was converted to the anion of acid amide (68) by sodium amide (69TL3887), while 2-(4 -nitrobenzoyl)-3-phenyl-oxaziridine (69) afforded the diacylimide (70) by addition of cyclohexylamine to its benzene solution at room temperature (67CB2593). 

Complete conversion into sodium amide is indicated by cessation of gas evolution and disappearance of the blue color of the solution. This generally requires 20-30 minutes and results in a gray suspension of sodium amide in a dark-gray reaction medium. 

A solution of sodium amide (0.226 mole) in liquid ammonia is prepared in a 1-1. three-necked tlask equipped with a condenser, a ball-scaled mechanical stirrer, and a dro ii)ing funnel. Commercial anhydrous lii(uid ammonia (500 ml.) is introduced from... 

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