— iig — 



CH 3 \ 



)C = CH. CH„ . CH, — CH — CH, • CH 2 OH (rhodinol), 



ch/ "I 



CH, 

 and to the latter 



\C — CH, — CH 2 -CH, . CH — CH 2 . CH 2 OH (citronellol) 

 CH/ . | 



CH 8 



Bouveault 1 ) supports this view by the difference in the behaviour 

 of the aldehydes; Harries 2 ) agrees with him, on the strength of the 

 results obtained by him in the oxidation of the, acetal of citronellal. 

 As we happened to have at our disposal citronellol obtained by 

 reduction from citronellal, we have produced from this alcohol the 

 pyruvic acid ester in accordance with Bouveault's directions, and 

 compared the semicarbazone of the latter with the corresponding 

 compound from citronellol occurring in nature. For both semicarba- 

 zones we found the melting point at no° to 1 1 1 °, and a mixture 

 of the two melted at the same temperature. In view of these results 

 we cannot agree with Bouveault's opinion that the alcohol C 10 H 20 O 

 in rose oil and pelargonium oil is not identic with the reduction pro- 

 duct of citronellal. 



In recrystallising the semicarbazones from ethyl alcohol we found 

 the melting point of the semicarbazones at 103 to 106 ; if the 

 melting point tube was dipped in sulphuric acid heated to 90 , the 

 substance melted already slightly below ioo°. Only after crystallising 

 from methyl alcohol and drying in the vacuum desiccator we found 

 the melting point mentioned above. It would appear that ethyl alcohol 

 participates molecularly in the crystallisation, or at least is held very 

 firmly mechanically, which would bring about the depression of the 

 melting point. 



Aldehydes and Ketones. 



On the estimation of aldehydes and ketones. 



An aldehyde -estimation by means of neutral sodium sulphite, 

 lately proposed by Sad tier has already been discussed by us in our 

 last Report (p. 48). This method consists of this, that the NaOH 

 liberated by the action of sodium sulphite on aldehydes, is determined 

 by titration, and from the result the aldehyde-content calculated. As 

 it is said to give very accurate results, the method is above all re- 

 commended for the citral- estimation in lemon oil. Sad tier also 



*) Bull. Soc. chim. III. 23 (1900), 458; Report October 1900, 77. 

 2 ) Berliner Berichte 34 (1901), 2081. Report April 1902, 90. 



