VE Pn eee ey PO ntee  eee Ne ate Sig i, fs 
} : Hi hea ast 
; ce. 
135 
+ of phenylethy! alcohol (b. p. 189 to 190°). Experiments with ethylal and a 
benz l-magnesium chloride led to toluene and high boiling hydrocarbons (most likely = 
Bithexaylmetnane) From isobutylal and magnesium benzyl chloride, toluene and dibenzyl 
resulted, and from magnesium phenyt bromide and acetal, the ethylether of phenyl- 
ethyl alcohol (b. p. 185 to 187°) was obtained, the yield being 50 per cent. The action. «a. nee 
of magnesium isobutyl bromide on acetal led to the ethylether of methylisobutyl car- 
binol, unknown before, a liquid of an intense and rather agreeable smell, reminding © 
somewhat of terpineol. B. p.121 to 122°; d25 0.7612. From magnesium benzyl chloride Poe 
and acetal, the authors obtained an ether of H.C CH ve 
the formula C;H;-CHe:CH(OC2H;):CHs; b. p. es we ie 
205 to 206°; diss 0.9159. It has an intense Hac HC CH-CH(OC,H;): CHs. 
smell of seats Through the action of p-me- H ee ee 
thylcyclohexyl bromide on acetal, the ether ; z A ey as aa 
was formed in addition to methyleyclohexene and dimethylcyclohexyl. Its b. p. lies : 
between 197 and 198° (752 mm); d2° 0.8564. Its smell is strong and recalls aniseed. = 
From acetone-acetal and magnesium isobutyl bromide, an ether of the formula 
(CHs)2C(OC2Hs)-CiHy resilted; b. p. 140 to 142°; d22 0.7833. It has a strong smell, 
_ similar to that of dipentene. 
ba 
ee eee 
ee 
Padres ectioks tat ngs SE 
é Hydrocarbons. cs i 
Isoprene. According to Staudinger and Klever') a good yield is obtained, if either 3 
limonene or dipentene, or both mixed, are heated with an indifferent gas to a high A * 
temperature under a pressure of 2 mm. They ascribe the rise in yield to the use of ee: 
'dipentene, &c., in a diluted state. The experiments of I. Ostromysslenski*) have shown, s 
however, that it is due to the formation of dipentene vapour at a low temperature. a 
- When pure limonene is being boiled for a considerable length of time, heavy oils and _ < 
solid hydrocarbons (polyterpenes) are formed; the reaction is hurried by sodium, but | 
_ in the presence of from 20 to 50 per cent. of benzene, limonene does not undergo any 
change, even aiter having been boiled for some time. On being heated, the limonene 
is obviously polymerized on the one hand (about between 150 and 250°) and, on the 
other, depolymerized to isoprene (between 500 and 600°). In order, therefore, to raise a 
the yield of isoprene, the temperature of from 150 to 250° must be avoided as far as 
_ possible and the dipentene heated straight off to 500 and 600°. On pyrogenous de- = 
composition of dipentene in naphthalene vapour, only traces of isoprene are formed; 
a mixture of 75 per cent. of naphthalene and 25 per cent. of dipentene does not yield — 
any isoprene at all. A low concentration of the dipentene vapour may likewise be 
obtained by subjecting it to a slow pyrogenation (from a dropping-funnel), when ex- 
_ tremely small quantities of isoprene result. On the contrary, a very high yield of iso-— 
prene is arrived at by subjecting dipentene, &c., to a pyrogenous decomposition in the 
vapours of a lower-boiling substance. On decomposing limonene in benzene vapour, 
70 to 75 per cent. of isoprene are obtained. Instead of benzene, one may use toluene, 
xylene or light petroleum; the reaction may be carried out under normal pressure. If 
benzene is used, only small quantities of hydrogen and diphenyl are formed. On de- 
composing turpentine under the conditions described, in addition to isoprene, gases 
and hydrocarbons boiling at from 60 to 150° are formed; the latter contain benzene, 
Wy we Ye 
J 
' toluene, xylene and cymene. They all act like benzene in the reaction. Turpentine — a 
z | a 
1) Berl. Berichte 44 (1911), 2212; Report October 1911, 127. — 7) Journ. russ. phys. chem. Ges. 47 (1915), S 
1947; Chem, Zentralbl. 1916, 1. 1133. a 
- 8 os \ < 4 
