Online Encyclopedia

Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.

FORMIC ACID, H2CO2

Online Encyclopedia
Originally appearing in Volume V10, Page 669 of the 1911 Encyclopedia Britannica.
» Make a correction to this article.
» Add information or comments to this article.
Spread the word: del.icio.us del.icio.us it!

FORMIC See also:

ACID, H2CO2 or H•COOH, the first member of the See also:series of aliphatic monobasic acids of • the See also:general See also:formula C;H2„02. It is distinguished from the other members of the series by certain characteristic properties; for example, it shows an aldehydic See also:character in reducing See also:silver salts to metallic silver, and it does not See also:form an acid chloride or an acid anhydride. Its nitrile (prussic acid) has an acid character, a See also:property not possessed by the nitriles of the other members of the series; and, by the See also:abstraction of the elements of See also:water from the acid, See also:carbon monoxide is produced, a reaction which finds no parallel in the higher members of the series. Finally, formic acid is, as shown by the determination of its See also:affinity See also:constant, a much stronger acid than the other acids of the series. It occurs naturally in red ants (See also:Lat. formica), in stinging nettles, in some See also:mineral See also:waters, in See also:animal secretions and in muscle. It may be prepared artificially by the oxidation of methyl See also:alcohol and of formaldehyde; by the rapid See also:heating of oxalic acid (J. See also:Gay-Lussac, See also:Ann. chim. phys., 1831 [2] 46,p. 218), but best by heating oxalic acid with See also:glycerin, at a temperature of roo-110° C. (M. See also:Berthelot, Ann., 1856, 98, p. 139). In this reaction a glycerol ester is formed as an intermediate product, and undergoes decomposition by the water which is also produced at the same See also:time.

Cal 5(OH)3+H2C20a = See also:

C3H5(OH),•OCHO+See also:CO2+H20 C8H1(OH)20•CHO+H20 = C:H°(OH)a+H2CO2. Many other synthetical processes for the See also:production of the acid or its salts are known. See also:Hydrolysis of hydrocyanic acid by means of hydrochloric acid yields formic acid. See also:Chloroform boiled with alcoholic potash forms See also:potassium formate (-J. See also:Dumas, BerzeliAs Jahresberichte, vol. 15, p. 371), a somewhat similar decomposition being shown by See also:chloral and aqueous potash (J. v. See also:Liebig, Ann., 1832, 1, p. 198). Formates are also produced by the See also:action of moist carbon monoxide on soda See also:lime at 190–220° C. (V. Merz and J.

Tibicira, Ber., 188o, 13, p. 23; A. Geuther, Ann., 188o, 202, p. 317), or by the action of moist carbon dioxide on potassium (H. See also:

Kolbe and R. Schmitt, Ann., 1861, 119, p. 251). H. See also:Meissen (Cornptes rend., 1902, 134, p. 261) prepared potassium formate by passing a current of carbon monoxide or carbon dioxide over heated potassium hydride, KH+CO:=KHCO2 and KH+2 C0=KHCO2+C. A concentrated acid may be obtained from the diluted acid either by neutralization with soda, the See also:sodium See also:salt thus obtained being then dried and heated with the See also:equivalent quantity of anhydrous oxalic acid (Lorin, See also:Bull. See also:soc. chim., 37, p. 104), or the See also:lead or See also:copper salt may be decomposed by dry sulphuretted See also:hydrogen at 13o° C.

L. Maquenne (Bull. sec. chim., 1888, 5o, p. 662) distils the commercial acid, in vacua, with concentrated sulphuric acid below 75° C. Formic acid is a colourless, See also:

sharp-smelling liquid, which crystallizes at o° C., melts at 8.6° C. and beils at 1oo•8° C. Its specific gravity is 1.22 (20°(4°). It is miscible in all proportions with water, alcohol and See also:ether. When heated with See also:zinc dust, the acid decomposes into carbon monoxide and hydrogen: The sodium and potassium salts, when heated to 400° C., give: oxalates and See also:carbonates of the See also:alkali metals, but the See also:magnesium, See also:calcium and See also:barium salts yield carbonates only. The See also:free acid, when heated with concentrated sulphuric acid, is decomposed into water and pure carbon monoxide; when heated with nitric acid, it is oxidized first to oxalic acid and finally to carbon dioxide. The salts of the acid are known as for-mates, and are mostly soluble in water, those of silver and lead being the least soluble. They crystallize well and are readily decomposed. Concentrated sulphuric acid converts them into sulphates, with simultaneous liberation of carbon monoxide. The calcium salt, when heated with the calcium salts of higher homologues, gives See also:aldehydes.

The silver and See also:

mercury salts, when heated, yield the See also:metal, with liberation of carbon dioxide and formation of free formic acid; and the ammonium salt, when distilled, gives some formamide, HCONH2. The See also:esters of the acid may be obtained by distilling a mixture of the sodium or potassium salts and the corresponding alcohol with hydrochloric or sulphuric acids. Formamide, HCONH2, is obtained by heating See also:ethyl formate with See also:ammonia; by heating ammonium formate with See also:urea to 140° C., 2HCO.ONH4+CO(See also:NH2)2 =2HCONH2+(NH4)2COs ; by heating ammonium formate in a sealed See also:tube for some See also:hours at 230° C., or by the action of sodium See also:amalgam on a See also:solution of potassium cyanate (H. Basarow, Ber., 1871, 4, p. 409). It is a liquid which boils in vacua at 15o°, but at 192–195° C. under See also:ordinary atmospheric pressure, with partial decomposition into carbon monoxide and ammonia. It dissolves mercuric See also:oxide, with the formation of mercuric formamide, (HCONH)2Hg.

End of Article: FORMIC ACID, H2CO2

Additional information and Comments

There are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML.
Site content, images, and layout Copyright © 2006 - Net Industries, worldwide.
Do not copy, download, transfer, or otherwise replicate the site content in whole or in part.

Links to articles and home page are always encouraged.

[back]
FORMIA (anc. Formiae, called Mola di Gaeta until re... 		[next]
FORMOSA

Site © 2006 - Net Industries