NOTES ON SUGAR CHEMISTRY ED. F. DEGERING
Punlue Uniwrsicy, Lafnyecte, Indin-
BECAUSE no other suear was commerciallv available in nractically unlimited quantity, the term wgar until rurcntly har hem b~rnoitsynonymous with sucrosr. The skyrocketing of the price of table sugar or oucruseduring the first World n'ar was the direct consequence of the lack of any satisfactory substitute, but now the price structure is materially changed by the daily production of hundreds of pounds of snow-white, crystalline glucose. The consumption of sugar by the human race dates back to the dawn of history. The use of honey, milk, and fruits doubtless represents the form in which this carbohydrate material first became a part of the human dietary. Sugar cane was known in ancient China. India, and Egypt. As early as the seventh century AD.. sugar had already become a commercial product. In the fifteenth century the production of sugar cane hecame a part of a great American industry by its introduction into Brazil and the West Indies. About four centuries later, the extraction of sugar from beets marked another important advance in the Amercan sugar industry, as evidenced by the fact that the sugar beet industry has now assumed commercial importance in the states of California. Colorado, Indiana. Kansas, Michigan, Montana, Nebraska, South Dakota. Utah, and Wisconsin, and is being produced in smaller amounts in some of the other states. The sugar cane and the sugar beet industries were not sufficiently flexible during the last emergency t o meet the sudden increase in demand. and forbadlookine - men of industrv assixntd rwearch warkcrs to the prohlem of producing cry%Aine glurojr from one of Amcrica'i first i.rops--com. We hart! today, ronscq~wnrly,the technic, the rapacity, and the raw material to produce a very satisfactory substitute for sucrose in almost any desired quantity in the form of crystalline glucose. Other substitutes now cbmmercially available are new sirups' such as Sweetose and Liquid Sugar, and powdered products such as Dri-Dex, Fro-Dex,and Malto-Dextrine. Among the newer derivatives of the sugars that are now available in semicommercial or commercial quantities may he included ethyl glucoside, glucose pentabutyrate, glucose pentapalmitate, glucose pentapropionate, and levulinic acid. In the comparatively recent advances in the chemistry of the sugars may be included the analytical separation of various classes of sugars, a new ascorbic acid synthesis, some new glucose deriva-, tives, hydrogenolysis of the sugars, irradiation of sucrose, the commercial production of lactic acid and its derivatives, the reduction of aldoses a t the dropping mercury cathode, and the phenolic derivatives of D+-glucose. Added t o these should be the topics considered in the "Annual ~ e v i r wof Biochemistry," such as con6gwatiou of the pyranoid ring. Walden inversion. acetohalogen sugars, cleavage of ester linkages, mesyl derivatives. nitrates, phosphates, carbonates, chromatographic separations. ethylideue compounds, sugars in solution, ozonalysis, Weeman reaction, monosaccharides, disaccbarides, and sugar acids. The analytical separation of the various classes of sugars has been effected by Hurd and Cantor through complete ethylation. rectification, and identification of the fractions of the alkylated product. The technic has been extended t o the identification of the constituents of corn syrup, and may he of value in following the degradation of the starch molecule. The qualitative identification of the natural sugars was outlined in detail by Militzer in the January, 1941, issue of this JOURNAL, and the determination of levulose in the presence of dextrose and sucrose is reported by Becker and Englis in the January. 1941, issue of the Analytical Edition of Industrial and Engineering Chemistry. D+-Glucose and D--fructose may be separated quantitatively, moreover, by the ~reoaratian of the azobenzene-b-henzavl derivative. . The hydrogenolysis of glucose has given DL-threitol, i-erythritol, anhydro-peutitol, hexanetetrol, and other products not yet identified. The treatment of sucrose by irradiation in the presence of uranyl salts has resulted in tbe production of reducing sugars,
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which mieht - sueeest .... that the oresence of reducine" suears in plants might bc the result of rither rynthcsi< or degradafiun. Lactic arid is bring produced hy thc controlled fermentation of either glurusc or lactose, and is availahlc in tank-car lots as a food ingredient or as a synthetic intermediate. Polarographic determinations, by the reduction of aldoses atithe dropping mercury cathode, indicate that the free aldehyde content of a glucose solution is of the order of 0.03 per cent and that the rest of the suear exists in the Dvranose or rine confieuratian. The Helferich a i d Peters synthesis of ascorbic acid (vitamin C) is indicated by the following series of reactions: ~
H.C:O
I H.C.OH 1
H0.C.H I
-
H.C:N.OH
I H.C.OH I
H0.C.H I
-
CiN
I 1
H.C.OAc Ac0.C.H I
CHXOH
-
~
H.c:o.'
1 then H0.y.H
ascorbic acid
The condensation of the suears of the reducine tvne ~ ~ ~ , ,with ~ phenolic compounds, hy Niedrrl and collaborators, givcs some insight into the iynthcsir of the rumplex derivativrsfound in nature as indicated by the following equatiqn: ~
~
~
~~~~
The reagents for the successive steps are: (1)HCI/AcOH, (2) continued heating in the presence of HCI/AcOH with the loss of 2H20, and (3) subsequent treatment with C6Hs.0H. Subsequent condensations follow the same general course. Sucrose octaacetate is now commercially available as a white crvstalliue solid. and finds use in certain tMes .. of adhesives. as a traniparcntizing agent for pnprr, as a plazticirer, and a . a denaturant for nthhing alcohol. One part of sucrose octaacetate in 100.0tru parts of water irnpnrts a pronounced hitter taste.
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