Notes on scientific research. 



135 



to 60 to 80° and rearranges itself to solid bornyl chloride. It is probable that whenever 



bornyl chloride is formed from pinene and hydrogen chloride, the unstable compound (III) is 



always formed intermediarily. 



CH2 CH2 CH 2 CH 2 



/ _ \ CI 



— c(CH, )2 — ^C-CH 3 HCf c^ch 3 ) 2 yti 



X CH 3 



CH 2 CH-C1 



(I) Bornyl chloride. 



CH 2 CH 



(II) Tertiary pinene hydrochloride. 



Nopinene, when submitted 

 to the same treatment, equally 

 gave rise to the identical 

 tertiary pinene hydrochloride 

 which with aniline passed 

 over into pinene and not into 

 nopinene. Since with the tertiary chloride the velocity of its rearrangement, at 0°, 

 exceeds its formation velocity from pinene and hydrogen chloride, it was not possible, 

 even at a low temperature, to obtain it free from bornyl chloride. Its odour is strangely 

 suffocating, and it attacks the mucous membranes. The mixture of hydrocarbons 

 obtained on scission with aniline consists mainly of pinene, but contains also some 

 dipentene, or limonene, and a still unknown cyclic terpene (in the fraction b. p. 162 to 167°). 



The action of hypochlorous acid on pinene, examined years ago by Wagner 1 ) and 

 his collaborators, has been investigated afresh by G. G. Henderson and J. K. Marsh 2 ). 

 These authors found that the products obtained formerly, two chlorohydrins, pinol oxide, 

 sobrerythritol, and nopinol glycol, are not the primery products of the reaction, but 

 are formed from these by the action of the potassium hydroxide employed. Treatment 

 of pinene (b. p. 156 to 157°) with a very dilute aqueous solution of hypochlorous acid 

 yielded two crude products of which the one was soluble in water. This product was 

 a mixture of three crystalline dichlorohydrins, CioHi 8 2 Cl2, which melted at 139 to 140°, 

 124 to 126°, and 155° respectively, together with a viscous, oily substance. The first of 

 these dichlorohydrins (nitrobenzoate, m.p. 175°) gave reactions identical with those of the 

 compound (m. p. 136°) prepared by Wagner and Slawinski. By direct synthesis of sobrerol 

 dichloride (os-l,2-dichloromenthane-6,8-diol, m. p. 138°) from i-sobrerol the authors 

 confirmed Wagner's view that pinene dichlorohydrin (m. p. 139°) and sobrerol dichloride 

 (m. p. 136°) are identical. (The mixture of both bodies showed the same m. p. 138°). 



On treatment with two molecules of aqueous caustic potash, the dichlorohydrin (1), 



m.p. 139°, formed pinol oxide and i-pinol glycol-2-chlorohydrin (III) Ci HnO 2 Cl (m. p. 104 



to 105°) which after heating with caustic potash solution gave rise to pinol oxide. An 



CH 3 



I 



CC1 



OH HC 



CHC1 



CH 3 



I ' 

 C 



CH 3 

 C(OH) 



OH-HC 



CHC1 



HC 



CHC1 



H 2 C l 



CH, 



CH 



OH.C(CH 3 ) 2 



H 2 C 



C(CH 3 ) 2 



CH 



H 2 C 



^C(CH 3 ) 2 



cu. 



CH 



(III) Pinolglycol-2-chlorohydrin 

 (m. p. 104°). 



(II) Isomeric intermediary (?) pro- 

 (I) Pinene dichlorohydrin (m. p. 139°). duct, chlorohydrin (m. p. 70 to 71°). 



isomeric, but entirely different chlorohydrin Ci Hi 7 O 2 Cl (m. p. 70 to 71°; nitrobenzoate, 

 m. p. 125°) was formed on shaking one mol. of the dichlorohydrin (m. p. 139°) with 

 one mol. potassium oxide in a very weak aqueous solution. This body was readily 

 transformed, by the action of water, into ?'-pinolglycol-2-chlorohydrin, m. p. 104°. It may 



') Cf. Report* October 1896, 88; October 1899, 63. 



2 ) Journ. chem. Soc. 119 (1921), 1492. 



