NOTES ON SCIENTIFIC RESEARCH. 145 
_ simplify the method of preparing o-eugenol by omitting the preliminary distillation of 
the guajacol allylether. Conversion of o-eugenol allylether results in the same 0, p-diallyl- 
guajacol, which is obtained in the form of a conversion-product of the allylether of 
common eugenol. The allylether of salicylic aldehyde, when boiled, affords readily and 
exclusively 3-allyl salicylic aldehyde. From the technical product, this salicylic aldehyde 
can easily be prepared in the pure state by means of the primarily-produced copper-salt. © 
Heating the o-vanillin allylether gives rise to a mixture of o-eugenol, allyl-o-vanillin, 
and allyl-p-vanillin. The allylether of common p-vanillin, when heated, yields 5-allyl- 
vanillin, m. p. 85 to 86°. 
Acids. 
Dihydrocamphoceenic acid. S.V.Hintikka') has resolved dihydrocamphoceenic 
acid by a simple method into isopropylcyclopentanone. He treated the acid with phos- 
phorus pentachloride and, when the reaction was completed, added the calculated 
quantity of bromine. The brominated acid was converted into hydroxydihydrocampho- 
ceenic acid, which, when oxidised with peroxide of lead in acetic solution, afforded 
isopropylcyclopentanone (apocamphenilone), b.p. 78 to 79° (11 mm.). The semicarbazone 
had m. p. 198°. 
The conversion of dihydrocamphoceenic acid amide into /-zsopropylcyclopentanone 
had already been carried out previously by L. Bouveault and G. Blanc’), albeit by a 
more complicated method. 
Camphane carboxylic acid. P. Barbier and V. Grignard*) have discovered 
interesting conditions of isomerism in camphane carboxylic acid (hydropinene carboxylic 
acid)*). This acid was prepared from pinene hydrochloride by the aid of Grignard’s 
reaction. It now appears that pinene hydrochloride apparently exists in two modi- 
fications. The B-modification is formed when an alcoholic pinene solution, warmed 
to 75 to 80°, is saturated with dry hydrogen chloride. A liquid substance is then 
formed from which a solid hydrochloride can be obtained by fractional distillation 
im vacuo. The A-modification of pinene hydrochloride is obtainable by passing hydro- 
chloric acid through pinene in the cold. By this method pinene from French turpen- 
tine oil ([¢]p — 35,17°) afforded a B-hydrochloride, with m.p. 126° ([@], — 21,66°) and 
an A-hydrochloride with m.p. 127° ([¢]) — 25,20°). The ethyl-magnesium compound of 
the B-hydrochloride yielded a labile dextrorotatory acid with m.p.76 to 78°, b.p. 157 
to 158° (16mm.), which was converted into stable levorotatory «-camphane carboxylic 
acid (/-bornyl carboxylic acid), m.p.88 to 89° by heating it with or without the addition 
of alcoholic potash liquor, aromatic amines or strong acids. From the A-hydrochloride 
the authors obtained a labile levorotatory acid (m.p.73 to 74°) which was convertible 
into a lzvorotatory stable acid,-m.p. 86 to 87° and which is most probably identical 
with the «-camphane carboxylic acid, m.p.88 to 89°, referred to above. From inactive 
B-pinene hydrochloride the authors obtained a labile racemic acid (Houben’s hydro- 
pinene carboxylic acid), m. p. 78 to 80°, which was converted into the stable r-camphane 
carboxylic acid, m.p.93 to 94°. 
Of all the acids only the stable ones, formed by the isomerisation of the labile 
acids, were fairly pure, all the labile acids were presumably mixtures. 
*) Ann. Acad. Scient. Fennicw. A.V. No. 2 (1914), p. 3. From a reprint kindly sent to us. — 2%) Compt. 
rend. 146 (1908), 233; Report April 1908, 191. — #) Bull. Soc. chim. IV. 15 (1914), 26. — +4) Comp. Report 
October 1913, 150. 
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