Notes on scientific research. 139 



of the wopulegyl acetates rarely amounted to 50 per cent., it was probable that the 

 aldehyde taking part in the condensation is the pure dextrorotatory compound of the 

 formula CH 2 : C(CH 3 )CH 2 CH 2 -CH(CH 3 )-CH 2 -CH0 1 ). 



The hydrogen phthalate of the mixture of alcohols obtained from the condensation 

 product could be separated by the fractional crystallisation of the magnesium and 

 strychnine salts. Magnesium 1-isopulegyl phthalate, C3 5 H4 2 8 Mg-6H 2 0, m. p. 111°; 

 strychnine salt, m. p. 205°; 1-isopulegol, b. p. 88° (10 mm.); d-a-isopulegol (still con- 

 taining, apparently, about 10 per cent, of 1-isopulegol), d^^ 0.9172; [«] D i 9 . 5 o + 29.3°. On 

 oxidation with chromic acid at 50°, gave isopulegones which gave identical laevorotatory 

 oximes (m. p. 121°, volatile in steam) and semicarbazones (m. p. 171°. When reduced 

 by hydrogen, the alcohols formed I- and a-neomenthol respectirely, both of which, when 

 oxidised, gave Z-menthone. 



The authors then give extensive tables on the constants of 1-isopulegol and its 

 esters with the fatty acids (C 2 to CiJ and graphs on the rotation of the esters as 

 influenced by temperature and wave-length. 



Menthol. — In a paper entitled, "Contributions towards the knowledge of derivatives 

 of /-menthol" (Zur Kenntnis der Ableitungsprodukte von l-Menthol), E. A. Ltick 2 ) reports 

 on some preparations obtained by him from /-menthol and menthone. By heating of 

 menthol with concentrated sulphuric acid for one hour he claims to have obtained 

 a sesquiterpene Ci 5 H 24 or C 3 oH 48 (sic) brownish-black, thickish mass) and furtheron, 

 by nitration, a nitrpsosesquiterpene (! nitrosesquiterpene) C 30 H 4 7NO 2 (decrepitating on 

 heating). Luck prepared also a menthyl cyanide and herefrom a menthane carboxylic 

 acid (termed by him methylene mentholic acid [sic]; white needles, the m. p. of which 

 could not be kept constant [sic]), the corresponding aldehyde, and from the latter the 

 secondary (!) alcohol, and a ketone. 



All these bodies are enumerated with their constitutional formula? (as Luck imagines 

 them to be) but without the least proofs of identity, without giving the necessary 

 constants, or any analytical results. It is desirable that the autor may supplement 

 his work in this respect and thus elucidate its results. 



Borneo!. — A process has been published 3 ) for the preparation of borneol from 

 turpentine oil, consisting in treating the oil with tetrachlorophthalic acid and decom- 

 posing the resulting dibornyl ester of the acid with alcoholic caustic soda solution. 

 A mixture of one pt. tetrachlorophthalic acid and 4 pts. turpentine oil, or crude pinene 

 is heated for twelve hours to 106 to 108°, then for two hours to, 125°, and finally for 

 six hours to 140°. After cooling the unattacked terpenes are removed by steam or 

 vacuum-distillation and the residue, mainly dibornyl tetrachlorophthalate, is saponified 

 by alcoholic sodium hydroxide. The borneol, purified in the usual manner, is optically 

 active and free from isoborneol. The yield amounts to 17 to 18 percent, of the crude 

 pinene employed. A large portion of the pinene as well as the tetrachlorophthalic 

 acid is recovered. 



If an organic solvent, such as anisole, a ketone, or an aromatic ester, is added 

 to the mixture of pinene and acid prior to the heating, the reaction passes off more 

 smoothly and the yield is raised up to 29 per cent. 4 ). 



*) Cf. the paper by Prins, Chem. Weekbl. 14 (1917), 692; Report 1918, 123. — 2 ) Apotheker-Ztg. 36 (1921), 

 279. — a ) Fahrigues des produits ehimiques de Thann et de Mulhouse. Fr. Pat. 510002, Nov. 25, 1920. Brit. 

 Pat. 144604, Dec. 3, 1919. Germ. Pat. Appl. F. 47011 published Jan. 12, 1922. — *) Brit. Pat. 158533, Nov. 1, 

 1920. (Add. Pat. to Brit. Pat. 144604.) As per Jourri. Soc. chem. Industry 40 (1921), A. 561. 



