1092 



witli the theoretical quant iiv of phthalie anliydride 30 grams of a 

 profhict boiling below J00°, which, however, on contiiined pnrificalion, 

 yielded the same amoimt of hexatriene. The boiling point (80°. 3 — 82°) 

 as well as the melting point (—34°. 5 to —29^} was higher than 

 that of the hydrocarbon prepared by the first method ; a pnre prodnct 

 could, however, not l)e obtained from the quantity at disposal. 



Hence, we had i-econrse to the preparation from a crystallized 

 substance namely from the above mentioned dibromide C^H.Br.^ 

 prepared, according to Gkinkr, by the action of i)hospliorus tribromide 

 on s.-divinylglycol. The bromide purified by rccrystallisation gives, 

 on treating the boiling alcoholic solution with zinc dust, a good yield 

 of pure hexatriene. This was placed over fused calcium chloride so 

 as to remove water and alcohol. xVfter fractionating in an atmosphere 

 of carbon dioxide or hydrogen a liquid was obtained (b.p. 80°.5 — 82° 

 at 765 m.m.) which solidified in a mixtui-e of ice and salt and 

 melted at — 11°.5 to — 9°.5 . d^C' = 0.7355. nd;j.7 ^^ 1.5150. 



MRd = 32.82. Calculated for C.H, 3 = 28.5. 

 For the specific exaltations were found: 



i^:s« = 5.ii 



E^j9=5.39 

 ^^iS - ^2 a = 1 -26 = 136.57„ 

 E v,^ - E^,, = 2.23 = 1527„ 



As will be noticed, the specific exaltations of the refraction reach 

 a remarkably high figure. 



Tf we allow bromine to act on a solution of the pure hexatriene 

 in carbon tetrachlorida or carbon disulphide, s-divinylethylenebromide, 

 m.p. 87°, is obtained quantitatively. 



Hexatriene gets readily polymerised, particularly on warming. As 

 in the above mentioned preparation of the hydrocarbon a fractional 

 distillation at the ordinary pressure was applied for the purpose of puri- 

 fication, there was a chance (hat in this operation the distillate 

 also might be contaminated with the polymeride. 



Therefore, a new supply was prepared which was dried, first 

 over calcium chloride and then over potassium hydroxide ^) ; it then 

 exhibited the following constants: m.p. =—11°; b.p. =80°- 80°.5 

 (at 755 mm.)di2 5=:0.7432. n;2.5 =3 1.5183 ; MRd =32.6. 



After a distillation in vacuo at which the hydrocarbon passed over 



1) If the hydrocarbon is pure, the KOH remains uncoloured. If, liowever, it 

 contains oxidation products, the latter turns brown at the surface. 



