Ethyl acetate hydrogen sulphate

CH3COOH + HOC2H5 - CH3GOOC2H3 + H2O If, however, concentrated sulphuric acid is present, the water is absorbed, the back reaction prevented, and a high yield of ethyl acetate is obtained. In practice the reaction is not so simple. It was formerly supposed that, since the sulphuric acid is usually added to the alcohol, ethyl hydrogen sulphate and water are formed, the latter being absorbed by the excess of sulphuric acid, A mixture of ethanol and acetic acid is then added to the ethyl hydrogen sulphate,... 

Under suitable conditions, certain chemical reactions will give rise to nacreous sulphur the most satisfactory result is obtained by allowing slow inter-diffusion of solutions of sodium thiosulphate and potassium hydrogen sulphate to occur.7 Another method involves the gradual decomposition of sulphur chloride or bromide by the vapour of water or methyl alcohol at the ordinary temperature.8 The decomposition of calcium polysulphidcs by hydrochloric acid,9 and of hydrogen persulphide by the addition of alcohol, ether, ethyl acetate or other organic solvents, also yields sulphur of the desired modification. 

Qualitative Examination.—A few grams of the substance are treated repeatedly with boiling water and filtered the solution may contain lead acetate and calcium sulphate (if both are present, however, soluble calcium acetate and insoluble lead sulphate are formed). In the solution lead is tested for with hydrogen sulphide, calcium (after elimination of the lead) with ammonia and ammonium oxalate, and sulphuric add with barium chloride. Acetic add may be detected in a separate portion of the substance by moistening it with sulphuric add and a few drops of alcohol and heating gently in presence of acetates, the odour of ethyl acetate is observed. 

Method B.104 In a 1-litre flask equipped with a condenser, a thermometer and a dropping funnel is placed 0.3 mol of lithium aluminium hydride (CAUTION, see Section 4.2.49, p. 445) in dry ether (300 ml). A nitrogen atmosphere is maintained throughout the reaction. To this stirred solution 0.45 mol of ethyl acetate is added over a period of 75 minutes maintaining the temperature at 3-7 °C. The reaction is stirred for an additional 30 minutes. To this solution at —10 °C is added 29.1 g (0.3 mol) of hexanenitrile in 5 minutes. The reaction temperature rises to 12°C in 10 minutes with the formation of a viscous solution. It is allowed to stir for another 50 minutes at 3 °C. The reaction mixture is decomposed by the addition of 300 ml of 2.5 m sulphuric acid. The ether layer is separated and the aqueous layer is extracted with ether. The combined ether extracts are washed with sodium hydrogen carbonate solution and water and dried over anhydrous sodium sulphate (1). 

Procedure for BOC-amino acids. A solution of the amino acid (10 mol) in a mixture of dioxane (20 ml), water (10 ml) and 1 m sodium hydroxide (10 ml) is stirred and cooled in an ice-water bath. Di-t-butyl pyrocarbonate (1) (2.4 g, 11 mmol) is added and stirring is continued at room temperature for 30 minutes. The solution is concentrated in vacuo to about 10-15 ml, cooled in an ice-water bath, covered with a layer of ethyl acetate (30 ml) and acidified with dilute aqueous potassium hydrogen sulphate solution to pH 2-3 (Congo red). The aqueous phase is extracted with ethyl acetate (2 x 15 ml). The ethyl acetate extracts are pooled, washed with water (2 x 30 ml), dried over anhydrous sodium sulphate and evaporated in vacuo. The residue is recrystallised with a suitable solvent (e.g. ethyl acetate-hexane). 

A mixture of the above compound (11 g) and ethylenediamine (27.8 g) is stirred at laboratory temperature for 3 days and the excess of ethylene diamine is removed by evaporation under reduced pressure. The residue is dissolved in methanol, the solution is cooled to 5°C and concentrated sulfuric acid is added until the pH of the solution is 2. A filter-aid (Celite, 10 g) is added and the mixture is stirred for 1 hour and then filtered. The filtrate is evaporated to dryness under reduced pressure and the residue is stirred with ethyl acetate. The mixture is filtered and there is thus obtained as solid residue 4-(N-beta-aminoethylcarbamoyl)morpholine hydrogen sulphate, melting point 168-169°C. 

NOTE.—The sulphuric acid used in the preparation serves as a catalytic agent. The amount of alcohol used is that equivalent to the acid (equal molecular proportions) plus that which combines with the sulphuric acid to form ethyl hydrogen sulphate. The ester obtained in the first distillation contains alcohol and acetic acid. The former is removed by shaking with calcium chloride, and the latter by treatment with sodium carbonate. 

Cognate preparations sulphuric acid catalyst. Ethyl butanoate. Use a mixture of 88 g (92 ml, 1 mol) of butanoic acid, 23 g (29 ml, 0.5 mol) of ethanol and 9g (5 ml) of concentrated sulphuric acid. Reflux for 14 hours. Pour into excess of water, wash several times with water, followed by saturated sodium hydrogen carbonate solution until all the acid is removed, and finally with water. Dry with anhydrous sodium sulphate, and distil. The ethyl butanoate passes over at 119.5-120.5 °C. Yield 40g (69%). An improved yield can be obtained by distilling the reaction mixture through an efficient fractionating column until the temperature rises to 125 °C, and purifying the crude ester as detailed above under methyl acetate. 

Methyl, ethyl, and propyl alcohols are oxidised by permanganate or hydrogen peroxide in the presence of ferrous salts. If ferrous sulphate is employed, the ethyl alcohol is, in dilute solution, oxidised by the permanganate to aldehyde but in the presence of ferrous oxalate the oxidation proceeds further, acetic acid resulting. Thus... 

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