Synthesis of Sugar 187 



(3) Evtn-y method of polymerising formaldehyde to sugar yields 

 * mixture of sugars, in which pentoses are included, and often 

 form the main yield. Pentoses are not direct products of photo- 

 gynthcsis in plants, but instead hexoses and their 6 or 12 carbon 

 derivatives, starch and polysaccharides. 



(4) It is as easy for the plant to produce sugar directly as to 

 produce formaldehyde. Tlius taking the process in three stages — 



/ CO,, + H,0 = C H O + HO + 



) C0, + H0 + H,0 = CH,H0 + 30 



j CHO + CH.HO =^J^^(). Biose sugar, 

 -or in one stage : — 



2CO, + 3H.O=°20jjO + 20, 



The. equation could also be represented as in 1, 2, 3. 



/H 



(1) 2CO, + 2H.,0=C=0 + HA + 02 



(2) 



(3) I +1 =2 I Biose. 



" H 



^5) This Biose sugar (glycoUic aldehyde) is readily polymerised 

 •oy sodium carbonate to acrose, a hexose.sugai'. 



(6) This mode of producing sugar -would be endothermic, as in the 

 plant. The production of sugar from the polymers of formaldehyde 

 involves an exothermic reaction which, under appropriate condi- 

 tions, is very violent. 



(7) Magnesium hydrate has a slowcj- polymerising action on for- 

 maldehyde than' any other metallic alkali. Since the presence of 

 magnesium in chloro^jhyll is hardly accidental, its relations to 



^glycoUic aldehyde when it is in organic combination merit future 



