Orientation primary hydroxyl groups

The observed differences [3] in the reactivity of primary hydroxyl groups were preparatively exploited in the structural modifications of oligosaccharides. The monomolar tritylation of phenyl a-maltoside gives the 6 - to 6- ratio of about 1.3, whereas 2.9 is observed for phenyl P-maltoside [269]. Generally, the orientation of... 

Fig. 4 depicts the molecules of maltose and lactose. Assiuning that the C2- and C4-hydroxyl groups of the nonreducing moiety of maltose fit the acceptor site as shown in Fig. 4, it becomes a matter of interest to see how some of the other acceptors fit this pattern. There is only one way in which lactose can be so oriented that two hydroxyl groups occupy locations similar to those of the C2- and C4-hydroxyl groups of the n-glucosyl residue of maltose this orientation is shown in Fig. 4. It will also be noticed that this arrangement of lactose places the C2-hydroxyl group of the n-glucose residue in approximately the same position as the primary hydroxyl group of...

One parameter for each monomer describes the orientation of the oxygen of the primary hydroxyl group (0(6)), with respect to the C(H) - C(5) bond. 

The most remarkable fact exhibited by this crystal structure is that the disorder of the primary hydroxyl groups of the host depends directly upon the orientations of the guest molecule- In all cases H-bonds are established between the primary hydroxyl groups of the host and the carbonyl groups of the guests. 

For the D-hexoses, the Cl conformation (reaction 2.15) is defined as the form in which the primary hydroxyl group (-CH -OH) is equatorial. It is also the form in which C-1 is down and C-4 is up when the orientation of the ring is in the standard position. The Cl conformation is, thus, sometimes called a conformation. The 1C conformation is then the form in which the primary hydroxyl group is perpendicular to the ring, or axial. In this form, the C-1 is up and C-4 is down this is called a C conformation. For the pyranose ring forms of the D-pentoses, the designation of the conformation has to use the positions of C-1 and C-4, since there is no primary hydroxyl group. 

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