rogenation of unsaturated tonnipours, 
eae certain: unsaturated | aldehydes were hydrogenated, it resulted that only 
es rnolseals of hydrogen was taken up if the concentration of the platinum was small, 
whereas 2 molecules of hydrogen were taken up under the influence of the same 
quantity of platinum, if the concentration was-greater. On converting an aromatic 
_ substance into a hydroaromatic one by catalytical reduction, groups liable to be easily 
- reduced may be protected by means of derivatives. According to A. Skita*), one thus 
~ obtains quantitatively hydrocinnamaldehyde on shaking 5 g. of cinnamaldehyde, dis- 
dissolved in only 50 cc. of acetic acid, absorb 2 molecules of hydrogen in the presence 
of the same quantity of colloidal platinum and quantitatively form hydrocinnamyl 
= alcohol. By conducting hydrogen into a solution of 10 g. of cinnamaldehyde in 100 cc. 
_ of alcohol, in the presence of 10 cc. of ai per cent. palladous chloride solution, 20 cc. 
of a 2 per cent. gum arabic solution and 30 cc. of water, the cinnamaldehyde absorbs 
- 1 molecule of hydrogen and forms hydrocinnamaldehyde; in addition, a slight amount 
of cinnamyl alcohol is formed. If 6 g. of cinnamaldehyde, dissolved in 45 cc. of glacial 
acetic acid, are introduced into a solution of 10 cc. of a 5 per cent. chloroplatinic acid, 
25 cc. of a 2 per cent. gum arabic solution and 10 cc. of colloidal platinum, and then 
_ saturated with hydrogen unter a pressure of 3 atmospheres, phenylpropyl alcohol 
 (b. p. 235°) and a little propylbenzene are formed. When hydrogen, under a pressure 
_ wf 4 atmospheres, is conducted into a solution of 5 g. of cinnamaldehyde, 50 cc. of 
glacial acetic acid, 10 cc. of a 10 per cent. chloroplatinic acid, 30 cc. of a 2 per cent. gum 
arabic solution and 16 cc. of a solution of 0.003 g of platinum per cc., hexahydro- | 
= phenylpropyl alcohol results, a colourless liquid of penetrating smell (dees 0.9358). 
Besides, insignificant quantities of propylbenzene, hexahydropropylbenzene and phenyl- 
propyl alcohol are formed. By oxidation with sodium bichromate and sulphuric acid, 
the hexahydrophenylpropyl alcohol is converted into hexahydrophenylpropaldehyde 
— (b.p. 87 to 88° at 15 mm.; semicarbazone, m. p. 128°). If 5 g. of benzaldehyde, dis- 
_ solved in 35 cc. of alcohol, are added to 25 cc. of a colloidal solution containing 
— 0.08 g. of platinum, and 10 cc. of water, and shaken with hydrogen under a pressure 
of 2 atmospheres, 1 molecule of hydrogen is absorbed and benzyl alcohol formed. 
_ But if 10 g. of benzaldehyde, dissolved in 90 cc. of glacial acetic acid, are mixed with 
~ 10 ce. of a 5 per cent. chloroplatinic acid, 25 cc. of a 2 per cent. gum arabic solution 
and 10 cc. of colloidal platinum are shaken with hydrogen under a pressure of 2 at- 
_ mospheres, toluene results, the yield being 80 per cent. A solution of 5 g. of benz- 
aldehyde in 90 cc, of glacial acetic acid, 10 g. of a5 per cent. chloroplatinic acid, 115 cc. 
_ of a 2 per cent. gum arabic solution and 8 cc. of colloidal platinum absorbs 560 cc. 
| _ of hydrogen within 12 hours, when hexahydrotoluene is formed. In order to convert 
benzaldehyde into hexahydrobenzaldehyde, benzaniline was first prepared and then 
_ transformed into benzylaniline in the usual way, with sodium and alcohol. The ‘benzyl- 
aniline, dissolved in acetic acid and in the presence of chloroplatinic acid, gum arabic 
solution and colloidal platinum under a pressure of 4 atmospheres quickly absorbed 
hydrogen and formed dodekahydrobenzylaniline, which was oxidized with potassium 
_ permanganate dissolved in acetone. The oil thus obtained, after having been mixed 
z with concentrated hydrochloric acid, was distilled with steam, when the hexahydro- 
= a passed over (b. p. between 160 and 165°; semicarbazone, m. p. 167°). In 
a similar way, Skita obtained phenylethyl alcohol, in addition to a little ethylbenzene, 
ee 
4 ¢ 
: 
1) Berl. Berichte 48 (1915), 1486, 1685. 
solved in 100 ce. of acetic acid, with colloidal platinum, whereas 5 g. of cinnamaldehyde, 
i 
ee 
