Glucose ring

Figure 12.2 Schematic representations of an a-cyclodextrin molecule showing the glucose rings and the overall topology...

Intermediate structure characterized by cell dimensions a — 13.81 A, b = 10.45 A, c = 7.92 A, / = 90°. The structure closely resembles that of cellulose and some cellulosic structural elements are present. The nitrate groups are located between the glucose rings in line with the a-axis. This structure exists between 12.3 and 13.2% N. 

It may be assumed that in this book sugars are always d unless they are specifically designated as l. When linkages remain uncertain abbreviated formulas are given. Because the glucose ring in lactose is free to open to an aldehyde and to equilibrate (in solution) with other ring forms, the name lactose does not imply... 

Quite remarkable are the successful attempts to synthesize C-silyl sugars28 directly at the glucose ring by means of hydrosilylation of unsaturated sugars — in contrast to previous negative forecasts29 ( nicht direkt am Glucosering 29 ). 

The ratio of intensities to variables was 55/37 (the K+ and Br positions were not varied). The final R factor was 0.058. At this R value, not all bond lengths and bond angles were acceptable. When the glucose ring was adjusted to correct this problem, the R value rose to 0.068. The final ring conformation and adjustment will be discussed in future publications. 

An even better scenario is to run a series of 1-D TOCSY experiments in which the mixing time is systematically increased while the proton being irradiated is kept constant. To illustrate these experiments, we irradiated the anomeric proton from the /3-anomer of the glucose ring in lactose at 4.67 ppm and run a series of experiments with mixing times ranging from 20 ms to 400 ms. The results of these experiments are shown in a series of stacked plots in Figure 5.26. 

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