— 206 



to splitting-off of water as do the free acids, because in the case 

 of the former certain bodies with high boilingpoints are formed. 

 These bodies, which have not yet been more closely examined, are 

 probably acetyl-compounds. 



The unsaturated cyclic acids, both those with a semicyclic and 

 those with a cyclic double-bond, when submitted to dry distillation, 

 give off carbon dioxide and yield identical hydrocarbons in which the 

 double-bond holds the same semicyclic position. This fact supports 

 the already formed theory that in the reaction above referred to the 

 molecule of the hydrocarbons with a cyclic ethylene-bond undergoes a 

 displacement of the double-bond. 



It was also noticed that the hydroxy-acid esters are not always 

 readily hydrolisable. The simplest cyclic hydroxy- acids, sue has pen- 

 tanol-, hexanol-, and p-methyl hexanol-acetic and -propionic 

 acids can be prepared in good proportions in the course of the 

 saponifacation process of the corresponding esters. 



The hydroxy-acids remain very stable during the process of saponi- 

 fication, but when subjected to dry distillation they are decomposed 

 at once into carbon dioxide and hydrocarbons; notwithstanding the 

 presence of water the principal products generated are hydrocarbons 

 with semicyclic double-linking. Formerly, only hexacyclic unsaturated ■ 

 hydrocarbons with semicyclic linkings had been converted into ketones 

 with an unsaturated ring, but this conversion-process has now been ex- 

 tended also to pentacyclic systems. 



From the large quantity of experimental material which has been 

 published, we select the following details : — 



When hexanolacetic acid is boiled with acetic acid anhydride 

 there results zf^-cyclohexene-acetic acid (m. p. 91 ; m. p. of the 

 amide 147 to 148 ); a little zJ 1 -cyclohexene acetic acid is formed 

 as a bye-product. When subjected to dry distillation in a hydrogen- 

 current zf^-cyclohexene acetic acid methene-hexane (b. p. 103 ; 

 digo 0,802; n Di9o 1,4499) is formed. 1,4-methyl-cyclohexanone yields 

 by bromo-acetic ester synthesis (after saponification), two modifications 

 of 1,4-methyl-cyclohexanol-acetic acid, viz., an a-acid, m. p. 141 

 and a /?-acid, m. p. 89 to 90 . Both acids, when boiled with acetic 

 acid anhydride, yield 1,4 - methyl - cyclohexene acetic acid 

 (m. p. 63 to 64 ). The amide forms lustrous flakes, m. p. 121 to 122 

 (from methyl alcohol). Under oxidation, 1,4-methyl-cyclohexanone 

 is formed, in addition to which, oxalic acid and an acid sparingly 

 soluble in benzene (m. p. about 140 ) are formed. Dry distillation 

 gives 1,4-methyl-methenehexane. The hydroxy-ester which is 

 formed in the process of condensation of 1,4- methyl- cyclo - hexanone 

 with a -bromo- propionic acid ester is readily saponifiable into methyl- 

 cyclohexanol propionic acid, melting at no to in° In addition 



