(b)Laetrile undergoes an analogous hydrolytic cleavage to yield the cyanohydrin of benzalde-hyde.25.29Comparing D-glucose, D-mannose, and D-galactose, it can be said that the confguration of C-2 hasa substantial effect on the relative energies of the a- and b-pyranose forms, but that the confgura-tion of C-4 has virtually no effect. With this observation in mind, write the structures of the pyranoseforms of the carbohydrates given in each part.(a)The b-pyranose form of D-gulose is the same as that ofD-galactose except for the confgura-tion at C-3.The axial hydroxyl group at C-3 destabilizes the a-pyranose form more than the bform be-cause of its repulsive interaction with the axially disposed anomeric hydroxyl group. Thereshould be an even higher byaratio in D-gulopyranose than in D-galactopyranose. This is so;the observed bya ratio is 88 : 12.(b)The b-pyranose form of D-talose is the same as that ofD-mannose except for the confguration
This is the end of the preview. Sign up
access the rest of the document.
This note was uploaded on 10/03/2011 for the course CHM 2210 taught by Professor Reynolds during the Fall '01 term at University of Florida.