Volume 1
A dictionary of applied chemistry / by Sir Edward Thorpe, assisted by eminent contributors.
- Thomas Edward Thorpe
- Date:
- 1912-1913
Licence: Public Domain Mark
Credit: A dictionary of applied chemistry / by Sir Edward Thorpe, assisted by eminent contributors. Source: Wellcome Collection.
29/776 page 17
![Potassium acetate C2H302K occurs in the sap of many plants, and of trees. Its mode of preparation is similar to that of sodium acetate. It is a deliquescent crystalline solid, soluble in 053 part ice-cold water, and in hot Avater forms a solution Avhich, boiling at 169°, contains 88 p.c. of the salt. When chlorine gas is passed through a solu¬ tion of potassium acetate, carbonic acid is evolved and a poAverful, unstable, bleaching fluid is pro¬ duced. Potassium acetate may contain the same impurities as the sodium salt. The di- and tri¬ acetates are prepared like those of sodium. Sodium acetate C2H302Na is formed (1) by the action of dilute acetic acid on sodium carbo¬ nate, the solution being evaporated and crystal¬ lised ; (2) by neutralisation of pyroligneous acid Avith soda, and evaporation and fusion of the salt to remove tarry matters ; (3) by the addition of Glauber’s salt to solution of acetate of lime or of lead. The solution is decanted and filtered from the precipitated calcium or lead sulphate, evaporated and crystallised, and the crystals dissolved and recrystallised. Methods (2) and (3) are used on the manufacturing scale. Sodium acetate forms monoclinic crystals, containing 3 molecules of A\ater ; has a strong saline taste ; is soluble in 2-8 parts cold Avater and in 0'5 boiling Avater. The crystals melt com¬ pletely at 75° and lose their Avater of crystallisa¬ tion at 100°. By solution of this salt in ordinary strong acetic acid and rapid evaporation the di¬ acetate of soda is formed ; when glacial acid is used the triacetate is produced. Sodium acetate is used for the preparation of acetic acid and in medicine ; for the preserva¬ tion of meat and other foods instead of salt. The saturated solution is occasionally used for filling carriage foot-Avarmers. The commercial acetate is liable to contain sulphates, chlorides and carbonates, and me¬ tallic salts. Tarry matters are frequently pre¬ sent from the pyroligneous acid used in its manufacture. Acetate of lime, and sulphate and carbonate of potash are occasionally added as adulterants. For the estimation of acetic acid in com¬ mercial acetates the method of Stillwell and Gladding in a modified form is used (v. supra). Alkyl Acetates. Acetic ethers. Acetic acid forms numerous acetates with organic radicles. Some of these occur in the oils from various seeds. Amyl acetates CgHn(C2H302). The folloAAdng isomeric amyl acetates are known :— 1. Normal amyl acetate, boiling at 147-6° (Gartenmeister); at 148-4° (737 mm.) (Lieben and Rossi). 2. Isoamyl acetate. 3. Methyl propyl carbinyl acetate, boiling at 133°-135° (Wurtz); at 134°—137° (Schorlemmer). 4. Methyl isopropyl carbinyl acetate, boiling at 125° (Wurtz). 5. Diethyl carbinyl acetate, boiling at 132° (741 mm.) (Wagner and Saytzeff). 6. Tertiary amyl acetate, boiling at 124° (750 mm.) (Flavitzky). Of these, only the second is of technical in¬ terest. Vol. I—T. 17 | isoAmyl acetate, generally known as amyl acetate (CH3)2CH-CH2CH20-C2H30, is a colour¬ less liquid of an odour resembling that of jar¬ gonelle pears. Sp.gr. 0*8762 15°/4° (Mendeleeff), 0-8562 22°/4° (Briihl), b.p. 138-5°-139° at 758-6 (Schiff). It may be prepared by distilling a mixture of 1 part amyl alcohol, 1 part strong sulphuric acid,and 2 parts dried potassium acetate; or by warming a mixture of 1 part amyl alcohol, 1 part acetic acid and 0-5 part strong sulphuric acid on the Avater-bath and pouring the solution when cold into excess of Avater. The upper layer of purified amyl acetate is separated, shaken Avith a strong solution of sodium carbonate, again separated, dried over calcium chloride, and re¬ distilled. It may be prepared commercially from fusel oil, hydrochloric acid, and calcium acetate (Wilson, Eng. Pat. 4669). The commercial amyl acetate contains some of the other isomerides. It is insoluble in Avater, but dissolves in all proportions in ether, amyl alcohol, and ordinary alcohol. The latter solution is largely used under the name of Jargonelle pear essence for flavouring confectionery. Camphor, tannin, resins, &c., dissolve readily in amyl acetate. A solution of gun-cotton there¬ in is used as a varnish, for lacquering metals, &c., and in the form of a stiff jelly, mixed Avith opaque substances such as china clay, as a sub¬ stitute for celluloid. It is also used in the manufacture of photo¬ graphic films and in some smokeless poAvders. It has been recommended for use for the production of a standard flame in photometry (J. Soc. Chem. Ind. 1885, 262). The Hefner standard lamp burns amyl acetate as an illuminant. Ethyl acetate. Acetic ether C2H6(C2H302) is a fragrant limpid liquid of sp.gr. 0-9072 15°/15°, b.p. 77-5° (Perkin); sp.gr.° 0*92446 0°/4, b.p. 77'17° at 760 mm. (Young and Forty). For the preparation of acetic ether 3-6 pts. by Aveight of commercial absolute alcohol is mixed Avith 9 pts. sulphuric acid Avith constant stirring. After standing tAventy-four hours the mixture is poured on 6 pts. of fused sodium acetate (in small lumps), alkwed to stand for tAvelve hours and distilled. The product is rectified over cal¬ cium chloride and carbonate of potash and re¬ distilled. Clark recommends the following pro¬ cess : 283 c.c. (10 oz.) of rectified alcohol (sp. gr. 0-838) are placed in a flask, and 283 c.c. of sulphuric acid (B.P.) are added with constant stirring. The liquid should be cooled externally as far as possible, allowed to stand till the tem¬ perature has sunk to 15°, and 351 grams (12| oz.) of dried sodium acetate added gradually Avith constant stirring and cooling. The liquid is distilled until 400 c.c. (14 oz.) has passed over; this is digested for three days Avith 2 oz. freshly dried potassium carbonate and filtered. The filtrate is distilled on the water- bath until all but 1 oz. has passed over. On the large scale dried sodium acetate may be sub¬ stituted for the potassium carbonate with ad¬ vantage (v. further W. I. Clark, Pharm. J. [3] 1883, 777). Ethyl acetate is soluble in 8 parts of water at 0°, and somewhat less soluble in water at 15°. On the other hand, 1 part water dissolves c](https://iiif.wellcomecollection.org/image/b31355080_0001_0029.jp2/full/800%2C/0/default.jpg)
