172 



ALDEHYDES AND KETONES : FATTY GROUP [91J-S. 



Or crotonic acid combines with hypo- 

 bromous acid to form (with a-) some 

 /3-brom-a-hydroxybutyric acid, which 

 on heating with water gives /3-methyl- 

 glyceric acid (Melikoff, Ann. 266, 435 ; 

 Journ. pr. Ch. [3] 61, 554). 



Or crotonic acid combines with hypo- 

 chlorous acid to give a-chlor-/3-hydroxy- 

 butyric acid (Erlenmeyer and Miiller, 

 Ber. 15, 49 ; Melikoff, Ann. 2,34, 198), 

 which by the action of alcoholic potash 

 is converted into /3-methylglycidic acid 

 (Melikoff, loc. cit. 204). The latter on 

 heating with water at 100 gives 

 /3-methylglyceric acid (IblcL 308 ; and 

 Ber. 21, 2055), from which formic alde- 

 hyde can be obtained as above. 



Or /3-methylglycidic acid (potassium 

 salt) itself can be electrolysed (Pisar- 

 jevsky, loc. cit.). 



[K.] From ft-hydroooylutyric acid 

 [Vol. II] through a-crotonic acid [54 ; 

 L], and then as under J. Crotonic 

 aldehyde is among the products of 

 electrolysis of /3-hydroxybutyric acid 

 (v. Miller and Hofer, Ber. 27, 469). 



[L.] From acetoacetic ester [Vol. II] 

 through a-crotonic acid [54; I], and 

 then as above. 



[M.] From glycerol [48] and hydrogen 

 cyanide [172] through allyl cyanide 

 [54 ; F], aft - dibrombutyronitrile by 

 bromination, and the acid by hydro- 

 lysis (Palmer, Am. Ch. Journ. 11, 93). 

 Subsequent steps as above under J. 



Or from glycerol through glyceric 

 acid and pyroracemic acid [54 ; F], 

 and then as under H and J. Formic 

 aldehyde is among the products of 

 electrolysis of potassium glycerate (v. 

 Miller and Hofer, Ber. 27, 469). Silver 

 glycerate gives formic aldehyde on 

 decomposition by iodine (Herzog and 

 Leiser, Monats. 22, 357). 



Glycerol on electrolysis in dilute 

 sulphuric acid solution gives 'trioxy- 

 methylene' among other products (Re- 

 nard, Ann. Chim. [5] 17, 331 : see 

 also Bartoli and Papasogli, Gazz. 13, 

 387), and then as under D. 



Or from glycerol through trimethyl- 

 ene (see under n-propyl alcohol [15; E]), 

 which gives formic aldehyde when passed 

 with air through a red-hot tube (Wolkoff 

 and Menschutkin, Ber. 31, 3067). 



Or from glycerol through allyl alcohol 

 (see under ethyl alcohol [14 ; G]), the 

 latter giving acrole'in [lOl] and! then 

 formic aldehyde by ' contact ' oxidation 

 over heated platinum (Trillat, Comp. 

 Rend. 123, 833). 



[N".] From propionic acid [Vol. II] 

 through pyroracemic acid [54 ; O], and 

 then as under H, &c. 



Or from propionyl chloride and zinc 

 methyl through tertiary amyl alcohol 

 (see under aldehyde [92 ; E]). The 

 latter gives formic aldehyde among the 

 products formed by passing the vapour 

 mixed with air over a heated platinum 

 spiral (Trillat, Comp. Rend. 132, 1495). 



[O.] From tartaric or racemic acid 

 [Vol. II] through pyroracemic acid 

 [54; N], and then as above. Formic 

 aldehyde is among the products of 

 electrolysis of potassium tartrate (v. 

 Miller and Hofer, Ber. 27, 468). 



Or from tartaric acid through di- 

 hydroxymalei'c acid and glycollic alde- 

 hyde (see under furfural [126 ; E]). 

 The oxime of the latter on treatment 

 with acetic anhydride and sodium 

 acetate gives the acetyl derivative of 

 the nitrile, and this, on treatment with 

 ammoniacal silver oxide and distillation 

 of the product with dilute sulphuric 

 acid, yields formic aldehyde (Fenton, 

 Proc. Ch. Soc., 16, 148). 



[P.] From allyl isolhioct/anate [166] 

 through allyl cyanide [54 ; J], and 

 then through a/3-dibrombutyric acid, 

 &c., as under M. 



[Q,.] From malonic acid [Vol. II] by 

 electrolysis of a solution of the potassium 

 salt (Petersen, Zeit. physik. Ch. 33, 



714). 



Or from malonic and acetic acids 

 [Vol. II], and aldehyde [92 : paralde- 

 hyde] through a-crotonic acid [54; G], 

 and then as under J. 



[B.] From erythritol [50] and formic 

 acid [Vol. II] through crotonic aldehyde 

 [102] (see under normal butyl alcohol 

 [17; I]), and crotonic acid (see also 

 under benzyl alcohol [54 ; H]), and then 

 as under J. 



[S.] From mannitol [51], 'trioxy- 

 methylene' being among the products 

 of its electrolysis in dilute sulphuric 

 acid solution (Renard, Ann. Chim. [5] 



