— 123 — 



to 1 79 . When heated in vacuo for a prolonged time, carvone hydrate 

 is converted in carvacrol and carvone; when heated for one hour 

 with potassium bisulphate to 170 , it yields quantitatively carvacrol. 

 The hydroxyl-group could not be detected either with benzoyl chloride 

 or with phenyl isothiocyanate ; all efforts to condense carvone hydrate 

 with benzaldehyde also failed. Reduction with sodium and alcohol 

 led to dihydrocarveol hydrate 



XH(OH) — CH 2X / 



CH 3 .CH( >CH.C(OH) 



X CH 2 CH/ \ 



2 2 N CH 3 



melting point 11 2°; Md20°-|- I 9, 2 ° m 2 4>74 per cent, alcoholic solution. 



Reduction with zinc dust and potash liquor, carried out in a manner 



analogous to the reduction of carvone to dihydrocarvone, yielded 



dihydrocarvone hydrate of the boiling point 138 to 13 9 (9 mm. 



iqo 

 pressure); d^- 1,006; n D20°i>476; Md20 o — 18,5° in 18,48 per cent. 



alcoholic solution; semicarbazone melting point 150,5° to 15 1°. Di- 

 hydrocarveol hydrate could be oxidised with chromic acid and glacial 

 acetic acid to dihydrocarvone hydrate. 



Camphor. Dihydro camphoric acid, formed when camphoric acid 

 and potash are melted together, is, according to Martine, a-methyl- 

 a-isopropyladipic acid, which is also obtained on oxidation of benzylidene 

 menthone. In order to confirm this formula, G. Blanc 1 ) has made 

 an attempt to arrive at this acid by synthesis. 



He reduced for this purpose isopropylsuccinic acid, according to 

 a method 2 ) already described previously, with sodium in absolute 

 alcohol. The a- and fi - isopropyl - butyrolactones were treated with 

 phosphorus pentabromide and subsequently with alcohol. Thereby 

 is formed the ester 



CH 3X 



)CH-CH-COOC 2 H 5 

 CH 3 / I 



CH 2 — CH 2 Br 



which is converted with sodium methyl malonic acid ester, with 

 formation of 



CH 3 v 



>CH — CH — COOC 2 H 5 



CTT ' I 



/ CH 3 



CH 2 — CH 2 — C — COOC 2 H 5 



\cOOQH s 



*) Compt. rend. 141 (1905), 1030. 

 2 ) Compt. rend. 139 (1904), 203. 



