— n6 — 



and the three position-isomeric methene-methylcyclohexanes, with 

 reference to the special properties of the methene-group. The crude materials 



R \ 

 employed were the substituted acetic acids i ^>C(OH) • CH 2 • COOH, 



whose esters, as is well known, can be readily obtained by condensation 

 of the cyclic ketones with bromo acetic ester and zinc. It was once 

 more proved that the use of benzene as a diluent increases the yield 

 very advantageously. Of the most simple conversion- products of the methene 

 hydrocarbons, which can be obtained from the acetic acids by splitting off 

 H 2 and C0 2 , Wallach mentions in the first place the glycols and 



R \ 



nitrosochlorides. The former, I ^> C(OH) CH 2 OH, are formed by 



oxidation with I per cent, permanganate solution, when the hydroxy acids 



R\ R x 



I ">C (OH) COOH and ketones I ^> CO are also always obtained as pro- 

 ducts of further oxidation. The glycols, when treated with acids, yield with 



R \ 



elimination of water saturated cyclic aldehydes, I ")>CH «CHO, alongside 



R \ R 



of which unsaturated alcohols, I \C • CH 2 OH, occur in consequence 



of another progress of reaction. But the properties of the aldehydes 

 themselves which appear so to say as substituted acetic aldehydes, 

 and polymerise readily, have a considerable influence on the yield. 

 The odour of the saturated cyclic aldehydes ranges between that 

 of benzaldehyde and a higher fatty aldehyde. The semicarbazones 

 dissolve comparatively easily in water, but can be purified by 

 recrystallisation from boiling water. The nitrosochlorides of the 

 menthene hydrocarbons can be readily converted with alcoholic solu- 

 tions of piperidine into the generally well - crystallising nitrolamines 



R \ 1 



] ^>C(NC 5 H 10 )CH = NOH, and when hydrochloric acid is abstracted 



pass over into oximes. These can be split up by hydrolysis into 



R \ 



unsaturated aldehydes I \ C • CHO, which have a much more pronounced 



benzaldehyde odour, and whose semicarbazones are much more diffi- 

 cultly soluble in water and melt considerably higher than those of the 

 corresponding saturated aldehydes. Of the twelve aldehydes separated 

 off in the form of the semicarbazones, hexahydrobenzaldehyde is 

 the only one which up to the present has been examined more in 

 detail. 



