Synthesis of Sugar 171 



'CHi)0, and the solid slowly disappears in excess of hot water. In 

 ■cold water a large part is still present, .undissociated, after three 

 "d a,y s . 



Paraformaldehyde, or the polyhydrate, dissolves in a few hours 

 in excess of cold 2% NaHO, the liquid smelling of CHoO, but also 

 •containing a little sugar. In cold, strong 35% NaHO, solid para- 

 formaldehyde at once dissolves, forming a yellow liquid smelling of 

 CH2O, and containing sugar. It blackens and gives a caramel smell, 

 with sulphuric acid, gives Molisch's test (a naphthol) for carbo- 

 hydrates, and yields furfural on boiling with hydrochloric acid. 



Hence, paraformaldehyde and the polyhydrate yield sugar 

 immediately in contact with cold, concentrated soda, whereas for- 

 maldehyde does not. 



If hot, 35% XaHO is added in slight excess to nielttd parafor- 

 maldehyde, there is a sudden evolution of methyl alcoliol, and the 

 resulting brown liquid contains sodium formate and reducing 

 sugar. 



Hence it may be concluded that in boiling watei' the formaldehyde 

 •exists mainly as paraformaldehyde or the polyhydrate, and that 

 the alkali produces sugar, methyl alcohol and sodium formate, 

 when it reacts with paraformaldehyde or the polyhydrate, but only 

 or mainly sodium formate and iwethyl alcohol when it reacts 

 directly with formaldehyde. 



Suppose three molecules of di-molecular formaldehyde react with 

 ■ one of Barium or calcium hydrate, as folloAvs : — 



C,HA CH,OH 



nnn ,. HO ,. COOH CHO 

 U^ti.u.-F t5a^o"" COOH "^ CH^HO 

 C^HA CH.OH 



The upper and lower molecules may be supposed to separate into 

 'CO and CH5OH, the latter sepai-ating as methyl alcohol and the 

 former combining with the BaHo02 to form barium forjnate. In 

 some manner not understood one of hydrogen is by a kind of enzy- 

 matic action transferred from one portion to the otiier of the cen- 

 tral dimolecular formaldehyde 



CH.,0_CHO 

 CH.,0~Cir,HO 



yielding biose or glycollic aldehyde. This would represent a 

 maximum percentage polymerisation to sugar of 33%, and if 



