Chemistry. — "Cyclic Derivatives of Mannitol". By Prof. P. van 

 KoMBURGH and J. H. N. van der Burg. 



(Communicated at the meeting of October 28, 1922). 



Many years ago the researches on the decomposition of the for- 

 mates of polyhydric alcohols, and also those on the 1 . 3 . 5 . hexa- 

 triene, induced one of us (v. R.) in collaboration with Mr. Van Maanen, 

 to study the action of formic acid on mannitol.^) 



After they had succeeded in preparing the hexaformate of mannitol 

 it appeared against expectation that on being heated this substance 

 yielded no hexatriene or only traces of it; on the other hand it 

 yielded a product of the formula CjHgO, though in small quantities. 

 This product, which boiled at 107—109°, had already been obtained 

 by Faüconnier'), together with isomannide, on heating mannitol with 

 formic acid. 



Also the tetraformate of mannitane and the diformate of iso- 

 mannide were obtained by heating mannitol and formic acid, both 

 in pure state. Fauconnier') found already, that by heating the 

 diformate of isomannide only carbon oxide was evolved, with 

 formation of isomannide; when on the other hand the former was 

 heated, carbonic acid gas was formed, and again the oxide CgHgO 

 was obtained. 



The following constants were found for this latter product, which 

 is very strongly levo-rotatory. Bp. 107°, dj^ =0,9226, no,, = 1,3567. 

 With bromine it gives a liquid dibromide, C,H3Br,0, d!^-^:= 0,8622, 

 Bp. 15 mm. 118°. 5. A tetrabromide could not be obtained. 



Reduction with hydrogen, according to Sabatier and Sendehens, 

 gave with C.HgO, both at 110° and at 180° a product of the 

 formula CgHmO, which did not boil constantly under ordinary pressure 

 but at 16° at 23 mm. Hence only 1 mol. of hydrogen had been absorbed. 



In virtue of the decomposition of the di-formate of isomannide, in 

 which only carbon oxide is formed, (so that it may be assumed not to 



') Van Maanen, Diss. Utrecht, 1909. 



«) C. r. 100, 914 (1885). 



») Bull. See. Chim. N.S. 41, 125 (1884). 



