384 Kolbe and Lautemann on Salicylic Acid and its Homologucs. 



When salicylate of soda is treated with excess of pentachloride 

 of phosphorus, a syrupy fuming liquid distils over, which, on 

 cooling, deposits tabular crystals of a body free from chlorine. 

 The mother-liquor smells of phenylic alcohol. The body is 

 soluble in ether, and on evaporation of the etherial solution, 

 remains as a white woolly mass of crystals. This body has the 

 formula C 26 H 8 4 ; it appears to be a compound of oxide of 

 phenyle with an acid which differs from salicylic acid by contain- 

 ing two atoms of water less. This acid, C 14 H 4 O 4 , the authors 

 name provisionally lasylic acid; it would stand to salicylic acid 

 in the same relation that acrylic acid does to lactic acid : 



C 14 H 4 O 4 Lasylic acid. C 6 H 4 4 Acrylic acid. 

 C 14 H 6 O 6 Salicylic acid. C 6 H 6 O 6 Lactic acid. 



It has been already stated* that these authors obtained sali- 

 cylic acid by the action of carbonic acid on sodium-phenylic 

 alcohol. They then regarded this acid as being analogous to 

 carbovinic acid. This view they have given up. Such an acid 

 is formed ; but as carbovinic acid is decomposed by hydrochloric 

 acid into carbonic acid and alcohol, so the acid is decomposed 

 into phenylic alcohol and carbonic acid; while salicylic acid, 

 which is formed at the same time, is unaltered by it. 



When a stream of dry carbonic acid is passed into gently 

 heated cresylic alcohol, C 14 H 8 2 , and sodium added from time 

 to time, a mass is obtained from which, when dissolved in water 

 and treated with hydrochloric acid, a new acid is precipitated 

 crystallizing in beautiful large prisms. It is homologous with 

 salicylic acid, and greatly resembles it. It gives with iron the 

 beautiful purple colour, and when heated it decomposes into 

 carbonic acid and cresylic alcohol. Although it has a higher 

 atomic weight, it melts at 153°, which is 6° below the melting- 

 point of salicylic acid. The formation is thus : — 



C 14 H 8 2 + C 2 4 =C 16 H 8 O 6 . 



Cresylic Cresotic 



alcohol. acid. 



In like manner, by treating the homologous hydrated oxide of 

 thymylc, C 20 H 12 O 2 , with carbonic acid and sodium under the 

 same circumstances, a new acid is obtained, thymotic acid, homo- 

 logous with salicylic and cresotic acids, and with similar proper- 

 ties. Although it contains 22 equivalents of carbon, its melting- 

 point, 120°, is lower than either of the foregoing acids. Its 

 formation is quite similar. 



C 20 H 14 2 + C 2 4 =C 22 H 14 O 6 . 



Thymotic Thymotic 



alcohol. acid. 



* Phil. Mag. vol. xix. p. 213. 



