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.
18/776 page 6
![alcohol (Girard, Compt. rend. 91, 629 ; J. 1880, 695). They are formed readily by the interaction of aldehydes with very dilute alcoholic hydrochloric acid (Fischer and Giebe, Ber. 30, 3053 ; 31, 545). Ketonic and aldehydic acetals, both aliphatic and aromatic, are formed by the interaction of nascent orthoformic ester and the necessary ketone or aldehyde in the presence of hydro¬ chloric acid (Claisen, Ber. 31, 1010; Annalen, 237, 269). The acetals are liquids having aromatic odours, and are sparingly soluble in water, from which they can again be separated on addition of concentrated calcium chloride solu¬ tion. They are readily soluble in alcohol and ether; their vapours or their solutions in alcohol benzene or acetones slowly harden dry gelatin films (Beckmann and Scharfenberger, Chem. Zentr. 1896, ii. 930). When heated in a closed tube with glacial acetic acid, the corresponding aldehyde is obtained (Beilstein, Annalen, 112, 239). According to Bachmann (Annalen, 218, 45) the series of acetals can be descended by heating any member of the group with an alcohol containing a smaller number of carbon atoms than is present in its alcohol residue ; for example, diethylacetal and methyl alcohol yield climethylacetal and ethyl alcohol; but the reverse change, if it occurs at all, results in the production of very small quantities of the higher acetal. Delepine (Compt. rend. 1901, 132, 331, 968) finds, however, that when some acetals are boiled with any alcohol in the presence of a few drops of hydrochloric acid, a balanced reaction takes place. Thus whether methylal is heated with amyl alcohol or diamyl formal with methyl alcohol, the result is the same, the products con¬ sisting of a mixture of methylal, diamyl formal, methyl and amyl alcohols and the mixed acetal MeO,CH2*OC5H11, the products of higher mole¬ cular weight predominating. Mixed acetals— that is, acetals containing two different alcohol residues—described by Bachmann (l.c.), con¬ sist of mixtures of molecular proportions of two distinct acetals (Riibencamp, Annalen, 225, 271; Fritsch and Schumacher, Annalen, 279, 308), but Delepine (l.c.) seems to have obtained such acetals and also their chloro- derivatives. The latter have also been obtained by Magnamini (Gazz. chim. ital. 16, 330). The following acetals have been prepared : methylal, which is an excellent solvent for many organic compounds (Kane, Annalen, 19, 175 ; Briihl, Annalen, 203, 12); ethylidene-dimethyl (Arlsberg J. 1864, 485), -dipropyl, and -diiso¬ butyl (Girard, J. 1880, 695), and -diisoamyl ether (Arlsberg, J. 1864, 486) ; propylidenedi- propyl ether (Schudel, Monatsh. 5, 247); iso- butylidenediethyl ether (Oeconomides, Bull. Soc. chim. 35, 500); and amylidene-dimethyl, -diethyl, and -diisoamyl ether (Arlsberg, l.c.). Glycoiacetal, a derivative of glycolaldehyde, has also been prepared (Pinner, Ber. 5, 150 ; Varley, Chem. Zentr. 1899, ii. 919). A large number of halogen alkyl and other acetal compounds have been prepared (Fischer, Ber. 26, 464; 41, 2860; 42, 1070 ; Fritsch (lx.) ; Wolff, Ber. 21, 1481 ; Wohl, Ber. 21, 616; 22, 568, 1353; Wohl and Lange, Ber. 40, 4727; Heller, Lob, Alexander, Ber. 27, 3097, 3093, 3102 ; Fosse ncl Etlinger, Compt. rend. 130, 1194 ; Delepine, l.c. and Compt. rend. 131, 745; Stolid, Ber. 35, 1590 ; Oddo and Mameli, Gazz. chim. ital. 33, ii. 373; Atto, R. Acad. Lincei, 1905, [v] 14, ii. 587 ; Freundler, Compt. rend. 138, 289; Bull. Soc. chim. 1907, [iv] 1, 66; Tschitschibabin, J. pr. Chem. 1906, [ii.] 73, 326; Paal and Gember, Arch. Pharm. 246, 306 ; Arbusoff, J. Russ. Phys. Chem. Soc. 40, 637; Smiles, Chem. Soc. Trans. 1909, 1000). The mono- and di-acetal derivatives of catechol (pyro- catechin) are obtained by heating the mono- sodium derivative of catechol with monochlor- acetal (Moreu, Compt. rend. 126, 1656). ACETALDEHYDE v. Aldehydes. ACETAMIDE C2H5NO, or CH3.CONH2. (Hofmann, Ber. 15, 980; Schulze, J. pr. Chem. [2] 27, 512 ; Keller, J. pr. Chem. [2] 31, 364; Aschan, Ber. 31, 2344 ; Kiindig, Annalen, 105, 277; Abel, J. Soc. Chem. Ind. 1899, 515.) Acetamide is usually prepared by the dry distillation of ammonium acetate; a better yield (91-7 p.c.) and a purer product is obtained by distilling ammonium diacetate in the special apparatus described by Francois (J. Pharm. Chim. 23, 230). Between 135° and 195° acetic acid and water are evolved, and at 195°- 222° some acetamide passes over. When the temperature remains constant at 222° the dis¬ tillation is stopped, the residue being pure acetamide. A nearly theoretical yield is obtained by saturating a mixture of ethyl acetate and ammonia with dry ammonia gas at —10°, and after standing, fractionating in vacuo (Phelps, Amer. J. Sci. 24, 429). Acetamide forms white hexagonal crystals which are odourless Avhen pure, and melt at 81°-82° (Hofmann, Ber. 14, 2729; Mason, Chem. Soc. Trans. 1889, 107 ; Meyer, Ber. 22, 24; Forster, Chem. Soc. Trans. 1898, 791; Nicol, Zeitsch. anorg. Chem. 15, 397), boils at 222° (cor.) [Kiindig], is readily soluble in water, and when heated with acids or alkalis is con¬ verted into acetic acid and ammonia (Coninck, Compt. rend. 121, 893 ; 126, 907 ; 127, 1028 ; Dunstan a. Dymond, Chem. Soc. Trans. 1894, 220; Guebet, Compt. rend. 129, 61). Chlorine, led into fused acetamide, yields acetchloramide CHg-CONHCl; and bromine, in the presence of dilute aqueous potash or soda yields acetbrom- amide, which on distillation with concentrated aqueous soda is converted into methylamine (Hofmann, Ber. 15, 408); Buchner and Papen- dieck, Ber. 25, 1160; Selivanoff, Ber. 26, 423; Francis, Compt. rend. 147, 680 ; 148, 173; Behrend a. Schreiber, Annalen, 318, 371). Acetamide acts both as a base and an acid (Pinner and Klien, Ber. 10,1896), combining with hydrogen chloride or nitric acid, and forming compounds in which a metal takes the place of one atom of hydrogen, as C2H30 -NHAg (Strecker, Annalen, 103, 321 ; Tafel and Enock, Ber. 23, 1550; Blacher, Ber. 28, 432; Hofmann and Bagge, Ber. 41, 312 ; Titherley, Chem. Soc. Trans. 1897,467). According to Forster (Chem. Soc. Trans. 1898, 783), mercury acetamide is a powerful dehydrogenising agent and owing to its tendency to exchange its mercury for hydrogen when the latter is attached to nitrogen, particu¬ larly when hydroxyl groups are in proximity, it can be employed as a convenient means of detecting primary and secondary hydrazines and primary hydroxylamines. It has also a](https://iiif.wellcomecollection.org/image/b31355080_0001_0018.jp2/full/800%2C/0/default.jpg)
