41-43 A.] 



MENTHOL 



93 



America), M. arvensis var. piperascens 

 (Japan), and var. glahrata (China) 

 (Dumas, Ann. China. 5O, 232; Ann. 

 6, 252 ; Blanchet and Sell, Ann. 6, 293 ; 

 Walter, Ann. 28, 312; 32, 288; Kane, 

 Phil. Mag. 16,418 ; Ann. 32, 285 ; Lau- 

 rent, Rev. Sci. 14, 341 ; Oppenheim,Ann. 

 120, 350; 13O, 176; Journ. Ch. Soc. 

 15, 24). In oil of pennyroyal from 

 Mentha pulegium (Tetry, Bull. Soc. [3] 

 27, 1 86). 



NOTE : The natural product is 1-menthol. 

 For observations on the genesis of menthol 

 compounds in Mentha piperita during the growth 

 of the plant see papers by Charabot, Comp. 

 Rend. 130, 518 ; 131, 806. 



SYNTHETICAL PROCESSES. 



[A.] From pulegone [128] by reduc- 

 tion with sodium in ethereal solution 

 (Beckmann and Pleissner, Ann. 262, 



32)- 



[B.] From menthone [129] as above 



(ttid.). 



42. Isopulegol. 



CH, 

 CH 



H,/ \H, 

 H a C CH(OH) 



\/ 



C 

 C(CH 5 ), 



H.C-CH.CH, 

 or (?) HO.HC CH, 



C . H 



CH 

 C(CH,), 



NATURAL SOURCE. 



Said to occur in citronella oil (Tie- 

 mann, Ber. 32, 825; compare Labbe, 

 Bull. Soc. [3] 21, 1023). 



SYNTHETICAL PROCESS. 



[A.] From citronellal [105] by the 

 action of acids or of acetic anhydride 

 (Tiemann and Schmidt, Ber. 29, 913; 

 30, 27). The transformation of pure 

 citronellal into isopulegol takes place 

 spontaneously (Labbe", loc. cit.). 



NOTE : The foregoing cyclic alcohols are included here on account 

 of their relationship to geraniol, linalool, citronellol, &c. 



KETONE ALCOHOLS. 



43. Acetol ; Acetyl Cat-bin ol ; 



Fyroracemic Alcohol ; Methylketol ; 



Hydroxyacetone ; Fropanonol ; 



Propanolone. 



CH S . CO . CH a . OH or CH, . C(OH) . CH, 



\r 



NATURAL SOURCES. 



From propylene glycol by the action 

 of the sorbose Bacterium in presence of 

 beer yeast infusion (Kling, Comp. Rend. 

 128, 244; 129, 1252). Certain varieties 

 of Mycoderma aceti produce the same 

 compound from propylene glycol (Ibid. 

 133, 231). 



SYNTHETICAL PROCESSES. 



[A.] From normal or isopropyl alcohol 

 [15 ; 16] through propylene and pro- 

 pylene chloride and u-chlorpropylene by 

 the action of alcoholic potash on the 



latter. a-Chlorpropylene by chlorina- 

 tion gives a3 (with a>/3) dichlorpropylene 

 = a-chlorallyl chloride (Friedel and 

 Silva, Comp. Rend. 73, 957 ; 74, 806 ; 

 75, 8 1 ; Fittig, Ann. 135, 359). The 

 latter on boiling with potassium car- 

 bonate solution yields a-chlorallyl al- 

 cohol (Henry, Comp. Rend. 95, 849), 

 which, on being dissolved in sulphuric 

 acid and on distilling the product with 

 water, gives acetol (Henry, Bull. Soc. 

 [2] 39, 526). 



Or from propylene through propylene 

 chloride and I : 2 : 3-trichlorpropane (see 

 under glycerol [48 ; A]). The latter by 

 the action of potassium hydroxide or tri- 

 ethylamine gives o/3-dichlorpropylene 

 (Reboul, Comp. Rend. 95, 993; Ann. 

 Suppl. 1, 229), which can be converted 

 into a-chlorallyl alcohol and acetol as 

 above. 



Or from propylene through the glycol 

 and the action of bromine in presence of 



