— 193 — 



the too-highly diluted solution. The yield of the two isomerides was 

 as follows: ioo g. camphocarbonic acid, or 90 g. crude borneol carbo- 

 xylic acid, gave 35 g. acid m. p. 171 , and 40 to 50 g. acid m. p. 101 . 

 The residue of 10 to 15 g. acid mixture remaining in the mother 

 liquors was afterwards treated for bornylene carboxylic acid. From 

 the toluene which had served for the purification of the two acids, an 

 acid melting at 12 6° could be isolated, which may either represent 

 a new isomeride, or possibly a eutectic mixture of the two known 

 acids. From the fact that the two last-named, when oxidised with 

 nitric acid, were converted into camphoric acid, the conclusion might 

 be drawn that the question at issue was only one of stereomery. By 

 means of dehydration the two modifications could also be converted 

 in the same unsaturated acid, viz., bornylene carboxylic acid (known 

 at the time as dehydroborneol or camphene carboxylic acid), although 

 not equally ready; the acid melting at 171 yielded its unsaturated 

 acid rather less readily than the acid of m. p. 10 1°. Hence, Bredt 

 designates the last-named acid cis, and the first-named cis-trans, bor- 

 neol carboxylic acid. The two isomerides are further differentiated 

 by the fact that the cis acid yields a calcium salt which contains 

 water of crystallisation, is more sparingly soluble in hot than in cold 

 water, and when oxidised with permanganate yields camphoric acid, 

 m. p. 1 86°; while the cis-trans acid gives an anhydrous calcium 

 salt of normal solubility and remains unchanged when oxidised with 

 permanganate. As already stated, both acids, when oxidised with 

 nitric acid, are converted into camphoric acid. Their behaviour towards 

 acetyl chloride is likewise the same in all essentials (the cis-trans acid, 

 with its high m. p. only reacting when heated, the cis acid reacting 

 without heat) and the same products are formed, partly acid, partly 

 neutral, according to the quantity of acetyl chloride employed. 

 Treated with only two parts of this reagent both acids yield the same 

 acetate I, m. p. 122 to 123 ; but when this is saponified only cis- 

 trans acid (m. p. 171 ) is regenerated, indicating a conversion of the 

 m-variety into the cis-trans isomeride. When treated with four parts 

 of acetyl chloride both acids yield a mixture of two indifferent products, 

 consisting (as concluded from the decomposition-products yielded by dry 

 distillation), of a mixture of the anhydride II of the acetylated 

 acid I, which, when distilled, is split up into acetic acid and bornylene 

 carboxylic anhydride III (m. p. 97 , b. p. 220 to 225 , 15 mm.) 

 and of a lactide-like anhydride IV, viz., cis-trans borneol carboxylic 

 acid. The latter, when distilled, is converted into two molecules of 

 bornylene carboxylic acid V (m. p. 112 to 113 ; b. p. 158 at 

 13 mm.). The latter acid could also be obtained by the slow distil- 

 lation of two borneol carboxylic acids in vacuo, but it can be prepared 

 more advantageously from the acetylation-products referred to. 



13 



