Ethyl 7-Hydroxyheptoate,-Potassium persulphate (50 g.) was gradually added to a well stirred
mixture of sulphuric acid (71 c.c., d 1.84) and water (24 c.c.) maintained below 15";
alcohol (100 c.c.) was then introduced, also below 15". The temperature being kept at 15', a
mixture of suberone (10 g.) and alcohol (30 c.c.) was added during 1 hour, and stirring was continued
for a further 1 1/2 hours. The mixture was diluted to 1 litre, filtered, saturated with
ammonium sulphate, and thoroughly extracted with ether. After removal of the solvent from the
dried extract, the residue was mixed with alcohol (15 c.c.) and sulphuric acid (1 c.c.) and heated
(bath at 110") for 6 hours. The product was isolated by means of ether and distilled, b. p.
140-146"/12 mm. (nearly all at 142") (7.5 g.), with a clear brown oily residue, b. p. 193"/0.5 mm.
(Found : C, 64-3; H, 10.4. C,,H,,O, requires C, 63.6; II, 9.9%). This substance appears to
be a di-ester of the formula OH-[CH,],CO*OfCH,] ,CO,Et, since it furnished the hydrazide
described below.
The main fraction, ethyl 7-hydroxyheptoate, afforded a phenylurethane, glistening white
plates from light petroleum, m. p. 64-65' (Found : N, 4.9. C,,H,,O,N requires N, 4.8%), and
a hydrazide, which crystallised from ethyl acetate as silky white needles, m. p. 121-123" (Found :
N, 17.6. In some experiments, under other conditions, the
odour of pineapples was very pronounced, and in such cases the yield was diminished. The substance
responsible for the odour is a volatile solid which we have not examined because our
object was to avoid its formation. Taking into consideration the work of Natta, Hill, and
Carothers (J. Amer. Chern. Soc., 1934, 56, 455) on the 14-membered ring dilactone related to
6-hydroxyhexoic acid, and of Ruzicka and Stoll (Helv. Chim. Acta, 1928,11, 1159) on the relation
between odour and number of ring-members in large-ring lactones, it seems certain that this
volatile odoriferous solid is the 16-membered ring dilactone related to 7-hydroxyheptoic
acid.
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