42 



XIV. 



-CHOH 



I 

 CHOCH, 



SECTIONAL ADDRESSER, 



XV. 



_CH O . 



I 

 CHOH 



X 



O 



o 



CHOCH, 



I 

 -CH 



I 

 CHOH 



I 

 CH2OCH3 



CHOH 

 CH -0 



CH.OH 



In order to accommodate the formation of maltose from starch either 

 one or two additional glucose residues must he present at X and Y in 

 the unit. Before developing a formula which will fulfil tlie above 

 conditions an outline of the reactions involved may l)e given: — 



STARCH 



I 

 Methvlated Starch (OMe = .30-4 %) 

 (13 grams) [o-h + 186-3'' 

 i 



V y i 



Trimethyl niethylglucoside Dimethyl methylglucoside Depolj'merised 



Methylated Starch 

 ^OMe = 37 %) 

 [«1d + SO'' 

 (4 grams) 



2, ^fi -Trimethyl glurose 

 (3 grams) 



Dimethyl glucose 

 (6 grams) 



2,3,5,6-Tetramethyl glucose 



It will be seen that the removal of trimethyl glucose and dimethyl 

 glucose in the molecular ratio of 1:2 is effected without alteration in 

 the composition of any methylated starch which survives hydrolysis. 

 The result is striking confirmation of the view that starch is based on 

 an anhydro-trisaccharide in which two hexose residues are linked in 

 a different fashion from the third. One of these is constituted as in 

 Formula XV., and the remaining two must be added in such a way 

 that at least one pair displays the essential structure of maltose.^* 



Four different structures may be built up to accommodate these 

 factors : — 



, 



i 



I 



— CH 



I 

 CHOH 



O I 

 I CHOH 



I I 

 — CH 



I 

 CH- 



-0 CH, • CHOH • CH ■ CHOH • CHOH • CH 



O 



XVI. 



-0 CH • CHOH • CHOH • CH • CHOH • CH 



CH,OH 



0- 



