— 159 — 



of hot dilute sulphuric acid. It also occurs in the reaction of hot 

 dilute sulphuric acid on the above-mentioned lactame, or on the amido 

 acid of the m. p. 155 . On continued heating with an excess of 

 concentrated hydrochloric acid, the lactame is converted, with loss of 

 carbonic acid and separation of ammonium chloride, into a dimorphous 

 acid C 10 H 12 O 2 of the m. p. 84 and 105 to 106 , which in the 

 authors' opinion probably represents the hitherto unknown 2, 3, 6-tri- 

 methyl benzoic acid. Its calcium salt, heated with soda-lime in vacuo 

 yields a hydrocarbon boiling at 166 to 168 , a trimethyl benzene, 

 which Lap worth and Wechsler were able to identify as pseudocumene 

 (2, 3, 6-trimethyl benzene), on the one hand by the tribromide melt- 

 ing at 224 to 2 2 6°, on the other by a mononitro derivative of the 

 m. p. 70 to 71°, and a trinitro product of the m. p. 183 to 184 . 



Fenchone. The fenchone semicarbazone, the production of which 

 had up to the present not yet been accomplished, was obtained by 

 Wallach 1 ) in the following manner: 10 g. semicarbazide hydrochloride 

 and 10 g. sodium acetate were dissolved in 20 cc. water, mixed with 

 a solution of 10 g. pure fenchone in 50 cc. alcohol, and left standing 

 for at least a fortnight at the temperature of the room. The alcohol 

 and unconverted fenchone were then driven off with steam, when 

 the semicarbazone remained behind. It crystallised from dilute alcohol 

 in large rhombic prisms of the m. p. 182 to 183 °. d- and 1-fenchone 

 showed the same behaviour with regard to the formation of the semi- 

 carbazones; a racemic mixture of the two semicarbazones melted at 

 172 to 1 73 and crystallised not so well. The optical rotatory power 

 was as follows: d-fenchone semicarbazone [«]d -\- 47,04°, in methyl 

 alcoholic solution; 1-fenchone semicarbazone [«]d — 46,88° in methyl 

 alcoholic solution. 



The production of the semicarbazones in the pure state is rendered 

 much more difficult if crude fenchone is used as raw material, as the 

 latter contains impurities which are difficult to remove. For example, 

 a 1-fenchone from thuja oil which was considered pure, yielded a 

 semicarbazone with a higher melting point which by recrystallisation 

 from much methyl alcohol could be split up in two fractions, of which 

 one melted at 238°, and the other at 182 to 183°. The ketone 

 regenerated from the higher-melting fraction was found to be 1-camphor 

 (Wd — 39>9° m ethereal solution). A separation of the camphor 

 from the fenchone is very difficult, and is only rendered possible by 

 the fact that the former reacts much more rapidly with semicarbazide 

 than fenchone. 



A more detailed examination by Wallach proved that the camphor 

 is not present as such in thuja oil, but is only formed during the 



*) Liebigs Annalen 353 (1907), 209. 



