1559T_ch24_423-43810/20/054:54 AM Page435 EQA Solutions to Problems.435 monosaccharides you know. OH HO OH -0 HO OH C OH OH OHOH is just B-D-glucopyranose. HO B HO HO O OPCH.OH HO CH.O8 ⊕ is just B-D-glucopyranose again, OH OH is also B-p-glucopyranose.Stevioside contains three molecules of glucose in its structure. 53.You of actose.Switch sereochemistry at CI for the isomer.Notice in the answer re of lactose.Switch stereoc HO BOH 52. The structure is shown below, with the three carbohydrate units labeled. Redraw each one separately, and then rotate it such that it is presented in a more conventional view that can be compared with monosaccharides you know. A is just
-D-glucopyranose. B is just
-D-glucopyranose again, C is also
-D-glucopyranose. Stevioside contains three molecules of glucose in its structure. 53. You can find a good conformational picture of
-D-galactose on page 1127 of the textbook, as the left￾hand part of the structure of lactose. Switch stereochemistry at C1 for the isomer. Notice in the answer below how the name, 3-(-D-galactopyranos-1-yl)-
-D-galactopyranose, translates into the structure: 54. The hydroxyl group at C1 leaves most readily when protonated, because a resonance-stabilized carbocation is produced. O OH OH2 HO HO CH2OH H2O Then H O OH HO HO CH2OH O OH HO HO CH2OH NH2 NH3 O OH HO HO CH2OH O OH O HO CH2OH OH 1 3
O OH OH HO HO CH2OH O OH HO HO HO O OH OH HO HO CH2OH CH2OH rotate 120 (1/3 turn) around vertical axis O OH OH HO O HO OH OH CH2OH CH2OH HO HO rotate 180 around horizontal axis O O O O O O O OH OH OH OH OH HO HO HO HO HO HO A B C Solutions to Problems • 435 1559T_ch24_423-438 10/20/05 4:54 AM Page 435