A D- Glucopyranose

In spite of their easy interconversion in solution a and p forms of carbohydrates are capable of independent existence and many have been isolated m pure form as crys talline solids When crystallized from ethanol d glucose yields a d glucopyranose mp 146°C [a]o +112 2° Crystallization from a water-ethanol mixture produces p d glucopyranose mp 148-155°C [aj +18 7° In the solid state the two forms do not mterconvert and are stable indefinitely Their structures have been unambiguously con firmed by X ray crystallography... 

D-Glucose is produced by complete depolymerization of starch with enzymes that catalyze the hydrolysis of both its (1 — 4) and (1 — 6) linkages. Crystalline a-D-glucopyranose is generally sold as dextrose. Glucose is also isomerized to D-fmctose to produce high fmctose com symp (HFCS). 

Compounds i, ii, and iii can be prepared by an acid-catalyzed reaction of a diol and the cycloalkanone in the presence of ethyl orthoformate and mesitylene-sulfonic acid. The relative ease of acid-catalyzed hydrolysis [0.53 M H2SO4, H2O, PrOH (65 35), 20°] for compounds i, iii, acetonide, and ii is C5 C7 > acetonide C (e.g., t.//s for 1,2-O-alkylidene-a-D-glucopyranoses of C5, C7, acetonide, and C derivatives are 8, 10, 20, and 124 h, respectively). The efficiency of cleavage seems to be dependent upon the electronic environment about the ketal. ... 

Thus the trans relationship between the hydroxymethyl group and the C-l hydroxy group in a-D-glucopyranose, and the cis relationship between the methyl group and the C-l hydroxy group in P-L-fucopyranose, are clearly shown. Note that representation of ketoses may require a different modification of the Fischer projection, as shown in the fructofuranose example above. Here C-2 is rotated about the bond with C-3 to accommodate the long bond to C-2 from the oxygen at C-5. 

Methyl 2,6-anhydro-a-D-altropyranoside-2 5B g l,4-Anhydro-ot-D-allopyranose-Bi,4 9 1,2-0-Ethylidene-a-D-glucopyranose- S3 10 p-L-Altropyranose-2So... 

Deoxy-2-phenyl-a-D-glucopyranose or 2-deoxy-2-C-phenyl-a-D-glucopyranose or (2fl)-2-deoxy-2-phenyl-a-D-arab/no-hexopyranose... 

Tri-0-acetyl-1,2-anhydro-a-D-glucopyranose not 3,4,6-tri-O-acetyM, 5-anhydro-p-D-glucooxirose... 

Tri-O-acetyl-a-D-glucopyranose (fl)-1,2-(methyl orthoacetate) or 3,4,6-tri-0-acetyl-[(fl)-1,2- >(1 -methoxyethylidene)]-a-D-glucopyranose... 

Note 1. The alternative name using a substituent prefix (see 2-Carb-35.1) is 2-amino-1-0,2-N-(benzylylidene)-2-deoxy-a-D-glucopyranose. 

P-D-Galactopyranosyl-(1 —>4) a-D-glucopyranose [p-D-Galp-(1 - 4)-a-D-Glcp] or4-0-p-D-galactopyranosyl-a-D-glucopyranose... 

P-D-fructofuranose a-D-glucopyranose 1,2 2,1 -dianhydride a-D-fructofuranose a-D-glucopyranose 1,1 2,2 -dianhydride P-D-fructofuranose a-D-glucopyranose 1,1 2,2 -dianhydride P-D-fructopyranose a-D-glucopyranose 1,1 2.2 -dianhydride P-D-fructofuranose a-D-glucopyranose 2,1 3,2 -dianhydride P-D-fructopyranose a-D-sorbopyranose 1,2 2,1 -dianhydride P-D-fructopyranose a-L-sorbopyranose 1,2 2,1 -dianhydride di-a-L-sorbofuranose 1,2 2,3 -dianhydride a-l-sorbofuranose a-L-sorbopyranose 2,1 3,2 -dianhydride di-a-L-sorbopyranose 1,2 2,1 -dianhydride a-D-sorbopyranose a-L-sorbopyranose 1,2 2,1 -dianhydride di p-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbopyranose p-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbofuranose a-L-sorbopyranose l,2 2,l -dianhydride P-L-sorbofuranose a-L-sorbopyranose 1,2 2,1 -dianhydride a-L-sorbofuranose P-L-sorbofuranose l,2 2,l -dianhydride... 

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