SYNTHESIS AND OLFACTIVE PROPERTIES OF 11-OXAHEXADECANOLIDE 27 . The place of the oxygen atom in the ring decides the olfactive properties of the molecule. More information may be found after completion of our intended synthesis of the still missing isomeric oxahexadecanolides. The possibility also exists that surprising discoveries in the field of olfaction will be made in other bifunctional macrocyclic systems. DISCUSSION DR. Y.-R. ]NAVES : Since the authors refer to the process for transforming oxa-acids into lactones described by Ogorodnikova and collaborators in 1955, I would like to emphasise that this procedure is, to some extent, a backward step with respect to the process described in British Patent 490,044, and involving the cyclisation of hydroxy-16-oxa-12-hexadecanoic acid. THE LECTURER: The difference between the two processes is that one is carried out via the polyester, while the patented method prepares a well- defined glyceryl ester as an intermediate. Lactonisation is effected in both cases by heating, in vacuo, with an alkaline catalyst in glycerol as a co- distillation component. 1. Ogorodnikova et al 9 3 hrs 8 hrs hydroxy acid * polyester --+ lactone 200 ø in vacuo 2. British Patent 490,044 NaOH 1 .chloropentanediol--2,3 hydroxy acid • sodium salt + $ hrs ---• glyceryl ester •- lactone. Comparing the two methods we conclude that the former procedure is more economical because (a) in the second case there is one reaction step more than in the former, (b) the first process can be completed in a single distillation appara- tus, whilst in the second the preparation of the glyceryl ester has to be carried out in a separate reaction vessel, and (c) prior to cyclisation it is necessary to wash the glyceryl ester with water, in order to remove the sodium chloride.

28 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS In our opinion, both lactonisation methods are in principle identical, as during transesterification the equilibrium to be obtained is essentially the same. MR. G. J. E. HAC•(FORTI•-JONES: The comparison between the isomers of oxahexadecanolide has proved most interesting. Has Dr. Klouwen any observations to make concerning the odours of the corresponding oxaheptadecanolides ? I have been informed that one of these is now on the market. T•E LECTURER: In the literature three isomeric oxaheptadecanolides are described, viz. 4-oxaheptadecanolide [Beets, M. G. J., and Meerburg, W. Rec. trav. chim. 72 411 (1953)• 8-oxaheptadecanolide6 and 12-oxahepta- decanolide [Tong, S. T., Soap Perfumery & Cosmetics 26 149 (1953)]. In our own laboratories, we prepared the 12-isomer and the unknown 11-oxahepta- decanolide. Both lactones proved to have an odour inferior to 10-, 11-and 12-oxahexadecanolide. As far as we know, no oxaheptadecanolides have been marketed up t• now.