170 



ALDEHYDES AND KETONES : FATTY GROUP [91 C-F. 



NOTE: Methylal can be obtained from methyl 

 alcohol by converting the alcohol into methyl 

 chloride and the latter into methylene chloride 

 by chlorination (Kegnault, Ann. Chim. [2] 70, 

 377 ; 'Ann. 33, 328). Methylene chloride inter- 

 acts with sodium methylate to form methylal 

 (Arnhold, Ann. 240, 190). 



Methyl alcohol gives formic aldehyde 

 among the products of the action of 

 chlorine or bromine (Lobry de Bruyn, 

 Ber. 26, 2Ji; Brochet, Comp. Rend. 

 121, 130). 



By the action of fuming sulphuric 

 acid on methyl alcohol there is formed 

 an c oxymethanesulphonic acid/ the 

 sodium salt of which gives formic alde- 

 hyde on decomposition by water (Mul- 

 ler, Ber. G, 1032). 



Or from methyl alcohol and acetic 

 acid [Vol. II] through methyl acetate, 

 chlormethyl acetate by chlorination 

 (Henry, Ber. 6, 740), and the action of 

 water at 100 on the latter (Michael, 

 Am. Ch. Journ. 1, 419). 



[D.] From ethyl alcohol [14] by in- 

 complete combustion (Mulliken, Brown, 

 and French, Am. Ch. Journ. 25, 1 1 1), or 

 by the incomplete combustion of ethyl 

 nitrate (Pratesi, Gazz. 14, 221). 



Or from ethyl ether, the vapour 

 giving a trace of formic aldehyde when 

 passed through a hot tube (Tis- 

 tschenko, Journ. Russ. Soc. 31, 784; 

 Ch. Centr. 1900, 1, 586). 



Or from ethyl alcohol through chloro- 

 form (see under methane [l ; D]), methyl- 

 ene chloride by reduction (Perkin, Ch. 

 News, 18, 106 ; Greene, Comp. Rend. 

 89, 1077 ; Jahresber. 1879, 49 ; Ch. 

 News, 50, 75 ; Journ. Am. Ch. Soc. 1, 

 522), and methylal as above under C. 



NOTE : The generators of chloroform referred 

 to under methane [1 ; M ; P ; R, &c.] thus be- 

 come, with methyl alcohol, generators of formic 

 aldehyde through methylal. 



Or from ethyl alcohol through ethyl- 

 ene, the latter giving formic aldehyde 

 when heated to 400 with an insufficient 

 quantity of oxygen for complete com- 

 bustion (Schutzenberger, Bull. Soc. [2] 

 31, 482). 



NOTE : All generators of ethylene thus be- 

 come generators of formic aldehyde. 



Or from ethyl alcohol through etJiyl- 

 ene glycol [45] (see under isopropyl al- 



cohol [16 ; C]). The latter, on electro- 

 lysis in presence of dilute sulphuric 

 acid, gives ' trioxymethylene ' (Renard, 

 Ann. Chim. [5] 17, 303), a polymeride 

 of formic aldehyde which is resolved by 

 heat, by hot water, or by combination 

 with acid sodium sulphite into the mono- 

 molecular aldehyde (Hofmann, Ber. 2, 

 152 ; Tollens and Mayer, Ber. 21, 1571 ; 

 Kraut, Ann. 258, 105 ; Harries, Ber. 

 34, 635 : see also Kekule, Ber. 25, 

 2435). Or trioxymethylene gives formic 

 aldehyde when passed with air through 

 a hot tube (Wolkoff and Menschutkin, 

 Ber. 31, 3067). 



Or from glycol through glycollic alde- 

 hyde (see under furfural [126 ; G]), and 

 then as below under O. 



Or from ethyl alcohol through iodo- 

 form (see under methane [l; D]), me- 

 thylene iodide by heating the latter 

 with hydriodic acid and phosphorus, &c. 

 (Butleroff, Ann. Chim. [3] 53, 313; 

 Hofmann, Ann. 115, 267 ; Baeyer, Ber. 

 5,1095). Methylene iodide gives me- 

 thylene chloride by chlorination (But- 

 leroff, Ann. 107, no; 111, 251), and 

 this, with methyl alcohol, is a generator 

 of methylal and of formic aldehyde as 

 above under C. 



Or iodoform and sodium ethylate give 

 acrylic acid (Butleroff, Ann. 114, 204). 

 From the latter through a-chlorlactic 

 and glyceric acid [54 ; I] or through 

 oxyacrylic (glycidic) acid [92; j], The 

 latter gives glyceric acid in contact 

 with water (Melikoff, Ber. 13, 272). 

 Subsequent steps as below under M. 



Or from iodoform through methylene 

 iodide and trioxymethylene by the action 

 of silver oxide (or oxalate) on the iodide 

 (Butleroff, Ann. Ill, 242). 



[E.] From acetic aldeJiyde\Q2\ through 

 iodoform by the action of iodine and 

 alkali [l ; I], and then as above under 

 D. Or from aldehyde through crotonic 

 aldehyde [102] and crotonic acid (see 

 under n-butyl alcohol [17 ; G] and 

 under benzyl alcohol [54 ; H]). From 

 crotonic acid through /3-methylgly eerie 

 acid to formic aldehyde as below under J. 



[F.] From acetone [106], formic alde- 

 hyde being among the products formed 

 by passing the vapour over a heated 

 platinum spiral (Trillat, Comp. Rend. 



