Chapter_22 - P1: PCX JWDD052-22 JWDD052-Solomons-v3...

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P1: PCX Printer: Hamilton JWDD052-22 JWDD052-Solomons-v3 April 30, 2007 11:13 22 CARBOHYDRATES SUMMARY OF SOME REACTIONS OF MONOSACCHARIDES Br 2 HNO 3 Aldonic acid Aldaric acid Osazone Cyanohydrin Aldose with one more carbon CHO CH 2 OH CO 2 H CO 2 H CO 2 H CH NNHC 6 H 5 C NNHC 6 H 5 CH 2 OH CH 2 OH CH 2 OH CH 2 OH CH 2 OH CHO CH 2 OH CN (CHOH) n (CHOH) n (CHOH) n - 1 (CHOH) n (CHOH) n +1 (CHOH) n - 1 (CHOH) n +1 several steps Alditol Aldose with one less carbon atom C 6 H 5 NHNH 2 (1) Br 2 /H 2 O (Ruff degradation) (2) H 2 O 2 /Fe 3 + H 2 O HCN (Kiliani-Fischer synthesis) NaBH 4 Open-chain form of aldose H O CH 2 OH C (CHOH) n Cyclic form of D-glucose CH 3 OH (CH 3 ) 2 SO 4 CH 2 OH O CHOH OH HO HO Methyl glucoside O CHOCH 3 OH HO HO HA CH 2 OH OH - 512
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P1: PCX Printer: Hamilton JWDD052-22 JWDD052-Solomons-v3 April 30, 2007 11:13 CARBOHYDRATES 513 H 3 O + O CHOCH 3 O CH 3 O CH 3 CH 3 O CH 2 OCH 3 O CHOH O CH 3 O CH 3 CH 3 O H CH 3 O CH 2 OCH 3 H H OCH 3 OCH 3 H OH H O C H 2 O CH 2 OCH 3 SOLUTIONS TO PROBLEMS 22.1 CHO CH 2 OH C * CHOH * CHOH CH 2 OH (b) Two, CH 2 OH (a) Two, O CHOH * CHOH * (c) There would be four stereoisomers (two sets of enantiomers) for each general structure: 2 2 = 4. 22.2 D CHO H OH C CH 2 OH C H OH D C O CH 2 OH HO H C CH 2 OH C H L CHO HO H C CH 2 OH C HO H L CH 2 OH HO H C CH 2 OH C HO H D CHO HO H C CH 2 OH C H OH D CH 2 OH HO H C CH 2 OH C H L CHO H C CH 2 OH C HO H L C O CH 2 OH H C CH 2 OH C HO H C O C O
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P1: PCX Printer: Hamilton JWDD052-22 JWDD052-Solomons-v3 April 30, 2007 11:13 514 CARBOHYDRATES 22.3 D-( + )-Glucose 2-Hydroxybenzyl alcohol and (a) HOCH 2 O OH OH HO HO Salicin (b) HOCH 2 OH 2 OH HO HO + O H + HOCH 2 O OH HO HO O + H HOCH 2 O OH HO HO H O H O HOCH 2 + O OH HO HO O H H - H + HOCH 2 O OH OH HO HO - HO CH 2 OH CH 2 OH CH 2 OH HO CH 2 OH 22.4 Dissolve d -glucose in ethanol and then bubble in gaseous HCl. + HOCH 2 O OE t OH HO HO + EtOH 2 + HOCH 2 O t OH HO HO HOCH 2 OH HO HO O OH Cl H HOCH 2 OH HO HO O O H H + - H 2 O HOCH 2 OH HO HO O H O Et + O Et H O Et H HOCH 2 + O OH HO HO
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P1: PCX Printer: Hamilton JWDD052-22 JWDD052-Solomons-v3 April 30, 2007 11:13 CARBOHYDRATES 515 22.5 Since glycosides are acetals, they undergo hydrolysis in aqueous acid to form cyclic hemi- acetals that then undergo mutarotation. Acetals are stable to base. 22.6 α - d -Glucopyranose will give a positive test with Benedict’s or Tollens’ solution because it is a cyclic hemiacetal. Methyl α - d -glucopyranoside, because it is a cyclic acetal, will not. 22.7 (e) No (f) HO HO CO 2 H H H H OH H OH (b) (a) Yes CO 2 H HNO 3 D-Threose HO H CH 2 OH H OH CHO D-Tartaric acid D-Mannaric acid HO H CO 2 H H OH CO 2 H (c) Yes H H CO 2 H OH OH (d) CO 2 H (g) The aldaric acid obtained from d -erythrose is meso -tartaric acid; the aldaric acid ob- tained from d -threose is d -tartaric acid. 22.8 or or H HO C OH O H H OH H OH C O O CO 2 H HO H H H C O H H OH H OH OH C OH O O O O CO 2 H HO H OH OH H HH and O O OH H H 22.9 One way of predicting the products from a periodate oxidation is to place an OH group on each carbon atom at the point where C C bond cleavage has occurred: CO H IO 4 - OH C H OH + H OH
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P1: PCX Printer: Hamilton JWDD052-22 JWDD052-Solomons-v3 April 30, 2007 11:13 516
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Chapter_22 - P1: PCX JWDD052-22 JWDD052-Solomons-v3...

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