( -^42 ) 



views of TiiiELE on the addition of hydrogen to conjugated systems 

 of nnsaturated compounds, then on reducing 



CH, CH, 



II I 



CH we might expect CH , 



1^0 ll/OH 



C C^ 



\h \h 



an unsaturated alcohol wliicli, however, by intramolecular atomic 



" ^0 

 shifting would be converted into CH, — CH^ — C , propylaldehyde. 



\H 



On further reduction this would form propyl alcohol, a substance 

 w^hich actually occurs among the products of the reduction. 



Up to the present, propylaldehyde has .not been found among the 

 substances formed in the reduction of acraldehyde. 



We have, however, succeeded in showing that, although no free 

 propylaldehyde may be present, a derivative of this substance is 

 formed under certain conditions so that the intermediate formation of 

 the said aldehyde is not at all improbable. 



First of all the reduction with zinc and hydrochloric acid in ethereal 

 solution according to Linnemann has been studied, but we succeeded 

 no more than Griner in isolating a well defined product — besides 

 allyl alcohol and perhaps smaller quantities of propyl alcohol ; 

 generally, the substance obtained, which boiled between 158°— 164°, 

 contained much chlorine. 



If, however, we allow zinc dust to act on a mixture of acraldehyde 

 and glacial acetic acid') then, in addition to aliyl and propyl alcohol, 

 a neutral liquid is formed (b.p. 170") from which, after fractionating 

 in vacuo, a product may be obtained boiling between 59^5 — 60'-' at 

 15 mm. The analysis and the vapour density lead to the formula 

 C,H,,0,. 



The comiiound is not decomposed by potassium hydroxide ; neither 

 sodium nor phosphorus jjentachloride have any action ; it cannot be 

 benzoylated with benzoyl chloride and pyridine. This sufticiently 

 proves the absence of OH groups. 



The said properties, however, render it very probable that the 

 substance is an etiier. By dilute acids it is hydrolysed although but 

 slowly. An aldehyde like odour appears but, as the reaction proceeds, 

 the mass becomes so ilark with formation of brownish-black resinous 



1) The action ol' various rudufing agonic on acraldi'liyde has been sludied. The 

 results will be published iu due course. 



