1903.] on Perfumes, Natural and Artificial. 261 



a refreshing odour of new hay, occurs in many plants, such as wood- 

 ruff, tonca beans, etc., and imparts to them their fragrance. 



Phenols and phenolic ethers are very important members of the 

 substances contributing to produce perfuming qualities. 



Especially important are those which contain an olefinic side 

 chain, such as anethol, eugenol, safrol, etc. 



The examination of the natural perfumes was useful, not only as 

 an extension of our knowledge of organic chemistry, but also for 

 commercial reasons, that is, for the introduction of the synthetical 

 essential oils into the market, reconstructed from the individuals 

 found in the natural product. We are now able to buy a number of 

 synthetical products, attar of roses, oil of jasmine, oil of neroli, etc. 



But not only were the complex products of nature reconstructed 

 synthetically, but the synthetical preparation of a number of chemical 

 individuals was also successfully achieved, and vanilline was the 

 pioneer in this direction. 



Thiemann obtained it first by oxidation of coniferin or coniferil 

 alcohol, and later on by the oxidation of acetisoeugenol. A number 

 of other modes are now known, but Thiemann's latter process is 

 technically still the most important one. The price of this aldehyde 

 has fallen from 150Z. in 1876 to 11. 5s. to-day. 



Heliotropin, protecatechu-aldehyde-methylene-ester, is likewise 

 prepared synthetically by the oxidation of piperonic acid or by the 

 oxidation of isosafrol ; it forms, like vanilline, an example of the 

 changes which are usually the result of competition, technical im- 

 provements and increasing consumption. Its price, which was once 

 761., has gone down to 15s. per pound. 



Anisaldehyde and cinnamic aldehyde are now prepared in the 

 laboratory. All these products, although artificial, are yet in another 

 sense products of nature ; that means, they are prepared synthetically, 

 but they occur all of them in natural perfumes, and they have only 

 been artificially produced for economic reasons. 



But there are two scents of very great importance which are 

 artificial in every meaning of the word : artificial musk and ionone, 

 artificial violet. 



Artificial musk, discovered by Baur, is trinitro-isobutyl-toluene or 

 xylene, and is obtained by nitration of isobutyltoluene, isobutyl- 

 xjlene, and isobutylhydrindene. 



There are a variety of these penetrating scents in which one of 

 the nitro-groups is replaced by other groups, such as the cyanogen, 

 halogen, ketonic and other groups, but the result from a perfuming 

 point of view is identical. 



Ionone, a ketone of the formula C13H20O, was discovered by 

 Thiemann and forms the subject of a series of the most remarkable 

 researches which this great scientist published. 



It is obtained by condensation of citral with acetone, and by con- 

 verting the new open chain ketone, which Thiemann calls pseudo- 

 donone, into its isomeric ketone by treatment with acids. 



