NOTES ON SCIENTIFIC RESEARCH. 127 
precipitation of the palladium. In reducing 10 grams of the substance, the required 
quantity of palladium chloride was added by degrees, whenever the process of reduction 
grew too slow. Under this treatment, 10 grams hydroxymethylene menthone absorbed 
the quantity of hydrogen calculated. for the two double bonds. A liberal yield of 
methylmenthone, boiling between 96 and 97° (13 mm.), was obtained. Hydroxymethylene 
camphor, when reduced by Willstatter’s method (deposited palladium black) afforded 
a poor yield of impure methyl camphor. A liberal yield of methyl camphor was 
obtained by reducing the chloride of hydroxymethylene camphor. Methylisothujon 
results from hydroxymethylenezsothujone by applying Skita’s inoculation method’). 
The absorption of hydrogen proceeded very slowly. The resulting methylsothujone 
had b. p. 229 to 230° (103 to 105° at 11mm.). Hydroxymethylene dihydrocarvone was 
reduced by the same method as hydroxymethylene menthone, giving rise to methyl- 
dihydrocarvone: b. p. 226 to 227°; semicarbazone, m. p. 168°. 
An article by E. Knoevenagel’) contains interesting observations on the action of 
various catalysts in acetylation. As is well known, it is not only organic compounds 
containing hydroxyl which are capable of being acetylated, but oxides, aldehydes, 
certain unsaturated and ether-like compounds, and unsaturated ketones, as well as 
the anhydrides of polyatomic alcohols in open- or ring-formation, also have the power 
of reacting with acetic anhydride. 
Knoevenagel proposes to apply the general term of acetolysis to formations of 
acetates which take place by the resolution of organic molecules. Herein he follows 
Skraup, who first observed such a molecular decomposition by the action of acetic 
anhydride in the case of cellulose. Knoevenagel also proposes to introduce the term 
“acetolysis by acetic anhydride”, analogous to the use of the expression “hydrolytic 
processes” for decomposition by the addition of water. The acetylation of the hydroxyl- 
compounds and the formation of acetates in the case of the other compounds mentioned, 
as well as the occurrence or absence of acetolytic resolution depend not only upon 
the temperature and the quantity of the catalyst employed, but also, in a high degree, 
upon the nature of the catalyst. Given an accurate knowledge of these conditions 
it is therefore possible, according to the nature of the experimental conditions, and 
concurrently with the acetylation of any hydroxyl-groups which may exist in the mole- 
cule, either to disrupt by resolution, or to leave unattacked, any oxide group (by the 
addition of acetic anhydride) and eventually also the molecule. 
Knoevenagel has treated with acetic anhydride numerous aldehydes, ketones and 
oxides in the presence of various catalysts. Among others he employed the following 
catalysts: ferric chloride, zinc chloride, sub-chloride of tin, trichloride of phosphorus, 
sulphuric acid, sulphoacetic acid, ferrous sulphate, copper sulphate, zinc sulphate, 
ammonium sulphate, and methylamine sulphate. The author employed three different 
methods of estimating the action of these catalysts, as follows: — 
1. By means of the rise in temperature caused by the catalysts, room-temperature 
being taken as the normal. 
2. By means of the yield of aldehyde diacetates. 
3. By means of the melting points of the crude acetates. 
The action of the catalysts may be judged by the aid of tables drawn up by the 
author, showing the temperature, the yield and, where possible, the melting- or boiling- 
point of the reaction-product obtained with each separate catalyst. 
*) Comp. Report April 1918, 134. — %) Liebigs Annalen 402 (1914), 111. 
