Frank George Pope

“ Uric acid takes up six hydrogen atoms per molecule and gives purone, C5H8N4O2, and it is apparently the oxygen atom attached to the carbon atom number 6 which is replaced by hydrogen, since when purone is heated with baryta, two molecules of carbon dioxide are liberated for one of purone. Consequently purone must contain two urea residues, which necessitates the presence of the >CO groups in positions 2 and 8. ”

“ Dipentene (i-limonene) is found widely distributed in many essential oils, e.g. of camphor, Russian turpentine, cubebs, bergamot, cardamom, &c., and is also a product of the dry distillation of many vegetable resins. It may be produced by heating many terpenes (pinene, camphene, sylvestrene, limonene) for several hours at 250–270° C.; or by the polymerization of isoprene at 300° C. To obtain pure dipentene it is best to heat dipentene hydrochloride with anhydrous sodium acetate and glacial acetic acid (O. Wallach, Ann. Chem. Pharm., 1887, 239, p. 3) . ”

“ Cineol, C10H18O, is an inner oxide of terpin. It is found in the oils of wormseed, cajaput, eucalyptus, laurel, galanga, camphor and of lavender. It may be prepared by passing a current of dry hydrochloric acid gas into wormseed oil, the precipitated hydrochloride being then distilled in a current of steam (O. Wallach and W. Brass, Ann., 1884, 225, p. 297) . It is an inactive liquid, which boils at 176° C. The oxygen atom in the molecule does not appear to possess either an alcoholic, ketonic, aldehyde or acid function.
Terpineol (Δ1-terpen-ol-8) , C10H17 (OH) . ”

“ This substance with phosphorus oxychloride yields 3-7-dimethyl-6-amino-2-oxy-8-chlorpurin, which on reduction with hydriodic acid leads to 3-7-dimethyl-6-amino-2-oxypurin, from which theobromine is obtained by the action of nitrous acid. It is also obtained by W. Traube's method (Ber., 1900, 33, p. 3047) from cyanacetyl methyl urea, which gives 3-methyl-4-5-diamino-2~6-dioxypyrimidine, whose formyl derivative yields 3-methylxanthine, from which theobromine is obtained by methylation. ”

“ The most important is the d-form, which is produced by the oxidation of d-camphor with nitric acid. it crystallizes in plates or prisms which melt at 187° C. Potassium permanganate oxidizes it to oxalic acid and Balbiano’s acid, C8H12O5, together with small quantities of camphanic, camphoronic and trimethyl succinic acids. It yields two series of acid esters, the allo-esters (1) , formed by the partial saponification of the neutral esters, and the ortho-esters (2) , formed by heating the anhydride with alcohols or sodium alcoholates. ”

“ It decomposes when heated, giving ammonia, carbon dioxide and hydroc anic acid. It possesses both acid and basic properties. When heated with concentrated hydrochloric acid to 220° C, it decomposes into carbon dioxide, ammonia, glycine and formic acid. Potassium chlorate and hydrochloric acid oxidize it to alloxan and urea. ”

“ This salt is then turned into the xanthate, C10H17OCS2Na, which with methyl sulphate yields the corresponding methyl ester. The unchanged isoborneol is removed by steam distillation, which also decomposes any methyl xanthate of isoborneol that may have been formed. The residue is crystallized and hydrolysed, when pure borneol is obtained. It behaves as a secondary alcohol. Nitric acid oxidizes it to camphor and when heated with potassium bisulphate, it gives camphene. With phosphorus pentachloride it forms a bornyl chloride, identical with pinene hydrochloride. ”

“ The terpenes all possess a characteristic odour and are fairly stable to alkalis, but are easily decomposed by acids or by heating to a sufficiently high temperature. Many polymerize readily, or are transformed into isomers by boiling with dilute alcoholic sulphuric acid. Some oxidize rapidly on exposure to air, passing into resinous substances. The formation of addition compounds with the halogens, halogen hydrides, and with nitrosyl chloride, is characteristic of many, whilst others unite readily with nitrogen peroxide. ”

“ Dimethyl-diamino-dioxypyrimidine (see Theophyllin above) yields a formyl derivative which on, treatment with sodium ethylate furnishes a sodium salt. This salt heated for some hours with methyl iodide yields caffeine. ”

“ It may be synthetically prepared from limonene nitrosochloride, alcoholic potash converting this compound into l-carvoxime, which on boiling with dilute sulphuric acid yields l-carvone; similarly terpineol nitrosochloride by the action of sodium ethylate yields oxydihydrocarvoxime, which on hydrolysis yields i-carvone. On heating with phosphoric acid carvone is converted into carvacrol (1-methyl-2-oxy-4-isopropylbenzene) . ”

“ Thujene (tanacetene) , C10H16, is a derivative of bicyclo- (0·1·3) -hexane. The name was first given to the hydrocarbon obtained by F. W. Semmler (Ber., 1892, 25, p. 3345) on the dry distillation of thujylamine hydrochloride. It is a liquid which boils at 60–63° (14 mm.) , and has been shown by L. Tschugaeff to be a monocyclic hydrocarbon, for which he proposes the name “isothujene.” The true thujene was prepared by L. Tschugaeff (Ber., 1900, 33, p. 3118) by heating the methyl xanthogenic ester obtained from thujyl alcohol. It is exceedingly unstable. ”

“ Nitrous acid converts it into xanthine. ¥Vhen oxidized by 'hydrochloric acid and potassium chlorate it yields guanidine, parabanic acid and carbon dioxide. 6-Amino-2-oxypurin, an isomer of guanine, is prepared by heating dichloradenine or 6-amino-2-6-8-trichlorpurin, obtained from 2-6-8 trichlorpurin and ammonia (Fischer, Bef., 1897, 30, p. 2239) with sodium ethylate to 130° C. and reducing the resulting 6-amino-2-ethoxy-8-chlorpurin with hydriodic acid (E. Fischer, Bef., 1897, 30, p. 2245) . ”

“ Chem., 1899 [2] , 60, p. 257) are to be regarded as tertiary esters; a similar type of reaction is found in the case of carvomenthol. A d-menthol has been prepared from the i-mixture obtained by reducing menthone with sodium. The mixture is benzoylated, and the liquid d-menthol benzoate separated and hydrolysed.
Tertiary menthol (terpan-ol-4) , a liquid boiling at 97–101° C. (20 mm.) , has been obtained by the hydrolysis of the ester prepared by heating menthene with trichloracetic acid (A. Reychler and L. Masson, Ber., 1896, 29, p. 1844) . ”

“ Xanthine, C5H4N4O2, or 2·6-dioxypurin, was discovered in 1817 by Marcet in a urinary calculus; it also occurs in various animal organs (the liver, pancreas and muscular tissue) , in urine, and in beetroot juice. ”

“ This latter substance by the action of pyridine yields tetrahydro-meta-toluic acid, the ester of which by magnesium methyl iodide is converted into Δ·1-meta menthenol-8 (2) . The meta-menthenol on dehydration by potassium bisulphate yields carvestrene (3) of boiling-point 179–180° C.
A synthetical monocyclic terpene, viz. 1-methyl-4-isopropyl dihydrocymene was prepared by A. v. Baeyer (Ber., 1893, 26, p. 232) . Succino-succinic ester is converted into the methyl isopropyl derivative, which on hydrolysis and elimination of carbon dioxide yields 1-methyl-4-isopropyldiketohexamethylene. ”

“ N'O2”' C;H;N;O;+CO;+CiI3NI-iz-{i2C2H5OH. Apocaffeine when boiled with water loses carbon dioxide and yields caffuric acid, C6H9N3O4, whichon hydrolysis with basic lead acetate is converted into mes oxalic acid, methyl amine and mono methyl urea. Reduction of caliuric acid yields hydro caff uric acid, C¢H9N3O3, which readily hydrolyses to methyl hydantoin. ”

“ It has also been prepared by condensing methylhexanone with ethyl acetate, the resulting methyl-1-acetyl-4-cyclohexanone-3 being converted into the isopropyl derivative, yielding acetylmenthone, which is then hydrolysed to menthone (G. Leser, Comptes rendus, 1902, 134, p. 1115) . A. Koltz and L. Hesse (Ann., 1905, 342, p. 306) convert methylhexanone (1) by means of ethyl oxalate and subsequent hydrolysis into methylhexanone oxalic acid (2) , the isopropyl ester of which on treatment with a methyl alcohol solution of caustic potash yields d-menthone (3) . ”

“ These bridges are distinguished by numbers, denoting the number of carbon atoms contained in them, the direct union of the two tertiary carbon atoms being designated as 0; if one carbon atom intervenes, then the number 1 is used, and so on. ”

“ The hydrocarbon is probably to be considered as being (CH3) 2C:CH· (CH2) 2·C (:CH2) ·CH:CH2 (Enklaar, Bulletin of Rouse-Bertrand fils, Nov., 1906, p. 92) . Ocymene is an isomer which can be extracted from the leaves of the basil. Enklaar (loc. cit.) represents it as (CH3) 2C:CH·CH2·CH:C (CH3) ·CH:CH2. Anhydro-geraniol, C10H16, the first olefine terpene isolated, was prepared in 1891 by F. W. Semmler ”