- i 7 6 - 



By the action of magnesium on dipentene dihydrochloride dissolved 

 in ether, Bar bier and Grignard 1 ) obtained three organomagnesium 

 compounds to which they give the formulae: — 



CH, 



/CH 8 .CH 2 /CH, 



C-MgCl NcH-C-MgCl 



X CH 2 -CH 2 \CH, 



CH 3 



/CH,. 



•CMgCl 

 ^CH 2 . 



CH, 

 NcH 

 CH, 



X CH, 



/CH- 

 CH 3 .C 



X CH, 



CH 2 

 NcH. 

 •CH, 



/CH 3 



■ C-MgCl 



\CH, 







There was further formed by splitting off hydrochloric acid, a fair 

 quantity of a terpene boiling about 171 to 1 75°, probably dipentene. 

 If the mixture of the magnesium compounds is treated with carbon 

 dioxide, and worked up in the usual manner, there results a mixture 

 of three acids; one dibasic, and two monobasic acids. If the ethereal 

 solution of the acids and the terpene is shaken with sodium bi- 

 carbonate solution, the dicarboxylic acid separates off (i. e., passes 

 over into the bicarbonate solution?); the monocarboxylic acids can 

 only be abstracted from the ether by means of dilute soda solution. 

 In this examination the authors only took the dicarboxylic acid into 

 consideration, and they gave to it the formula of a men thane- 1,8-di- 

 carboxylic acid : — /C H 2 .CH 2 /CH S 



ch„.c.coohVh«ccooh 

 \ y V 



CH 2 -CH 2 X CH 3 



This acid exists in two stereoisomer^ forms; the cis-modification 

 represents a powder of small crystals of the m. p. 192 (uncorr.), only 

 slightly soluble in cold water; the cis-trans-form , much more readily 

 soluble, but otherwise resembling the cis-form, melts at 174 to 175°- 

 The cis-acid, boiled with acetic anhydride, yields an anhydride soluble 

 in chloroform, which can be precipitated by ligroin; m. p. 145 to 

 148 (in a sealed tube). If this anhydride is heated in accordance 

 with Blanc's 2 ) directions to 250 to 350 , there is formed a viscid 

 oil, from which by rectification in vacuo a ketone-like body C u H 16 O 

 was isolated: — 



C l0 H 18 / No — C 10 H 16 :CO + CO 2 + H 2 . 

 \CCK 



The ketone is a light, green -yellow, oil with a strong camphor 

 odour, which is very mobile even at a low temperature, with the 

 following constants: b. p. 93 to 95 (13 mm. pressure); do© 0,9886; 

 di2,9° 0,9783; n D 1,49018; mol. refr. found 48,48, calculated 48,32. 



*) Compt. rend. 145 (1907), 255. 

 2 ) Ibidem 144 (1907), 143. 



