134 Report of Schimmel $ Co. April 1913. 



Ipatieff x ) also mentions an improvement in his method of hydrogenation which con- 

 sists in the introduction in his apparatus of an arrangement (designed by W. Werchoffsky) 

 or stirring under high pressures. This arrangement is on the solenoid-principle; 

 experiments for its simplification are still in progress. With the aid of this arrange- 

 ment Ipatieff was able to reduce a series of bodies which are otherwise difficult to 

 hydrogenate. Among these, using palladium as a catalyser, he obtained from geraniol 

 a satisfactory yield of a decanol, b. p. 105 to 106° (15 mm.); d 18Q 0,8280. Citral also 

 readily afforded a decanol, b. p. 107 to 108° (12 mm.); d L80 0,8296. 



As the simplest method of hydrogenating unsaturated bodies in a colloid platinum 

 metal solution, A. Skita and W. A. Meyer 2 ) recommend the addition to the solution 

 of platinum chloride and gum arabic of a colloid palladium or platinum solution. In 

 that case, as soon as the hydrogen is forced in, a colloid platinum solution is formed, 

 suited for transferring the hydrogen to the material which is to be reduced. In the 

 reduction of unsaturated ketones and aldehydes the addition of colloid platinum metals 

 is superfluous, because where these bodies are present when the hydrogen is introduced 

 a colloid platinum metal solution is immediately formed. But in the reduction of 

 bodies which are neither aldehydes nor ketones the platinum metal is precipitated in 

 granular form, under the action of hydrogen. Although palladium is capable, even in 

 this form, of attaching hydrogen to certain aromatic unsaturated groups, the method 

 fails when it is tried to attach aromatic double-bonds, that is to say in the case of 

 benzene, naphthalene, 8jc. For example, it was possible to reduce i-camphene in the 

 presence of palladium chloride and gum arabic in alcoholic solution, the palladium 

 being precipitated in the metallic form. Within about one hour the theoretical quantity 

 of hydrogen had been absorbed, dihydrocamphene (m. p. 53°; b. p. 161 to 162°), being 

 formed. 



The authors also describe the reduction of pinene from American oil of turpentine 

 (b. p. 155 to 160°) in alcoholic solution in the presence of a colloid palladium hydro- 

 protoxide solution. In this case pinane, b. p. 164 to 166°, resulted. 



We may in conclusion refer to the hydrogenation of cinnamic acid. To accomplish 

 this 7,4 grams cinnamic acid in dilute alcoholic solution was diluted with 0,2 grams 

 platinum-hydrochloric acid, 0,2 grams gum arabic and a colloid platinum solution 

 (0,0005 grams platinum) and shaken with hydrogen under 1 atm. over-pressure. The 

 double-bond was reduced within 15 minutes. 



Elsewhere 3 ) Skita and Meyer describe the hydrogenation of cenanthic aldehyde 

 fheptylic aldehyde) into heptylalcohol. 



Hydrocarbons. 



Pulegene. Wallach 4 ) nas discovered that it is impossible to reduce pulegene 

 sufficiently by Paal's method but that it can be so reduced by Skita's method. For 

 this purpose the hydrocarbon was emulsified in 5 p. c. acetic acid, diluted with palladium 

 chloride and gum arabic and shaken for three days in a hydrogen atmosphere. Dihydro- 

 pulegene (methyl- l-isopropyl-3-c?/cZopentane) boils between 142 and 144°, d 22 o 0,7730. 



Camphene. As stated in our Report of April 1912, p. 169, von Auwers, as a result 

 of spectrochemical investigation, has convinced himself of the accuracy of Wagner's 



Berl.BericMe 45 (1912), 3218. — 2 ) Ibidem3579. — 3 ) Ibidem 3593. — *) Liebig* Annalen 392 (1912), 58. 



