Quantenchemische MNDO-, AM1-, und PM3-Untersuchungen von α-D-Glucose-acetaten, -benzoaten und -(trichlor)acetaten als Modelle für die entsprechenden Amyloseverbindungen |
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Authors: | A H Otto S Schrader G Reinisch |
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Abstract: | Quantum Chemical MNDO-, AM1-, and PM3-Studies of α-D -Glucose Acetates, -Benzoates and -(Trichloro)Acetates as Models for the Respective Amylose Compounds. Heats of formation have been calculated for α-D-Glucose and also for its mono-, di- and trisubstituted derivatives (acetates, benzoates and (thrichloro)acetates in the positions 2, 3 and 6), applying the semiempirical quantum chemical methods MNDO, AM1 and PM3. When only one hydroxyl is substituted, the thermodynamic probability of generation decreases as 6>3>2 (acetates), 2>6>3 (benzoates) and 6>2>3 ((thrichloro)acetates). Generation of glucose monoacetate increases the reactivity of acetylation for both of the other OH groups. That was not established for benzoates and (trichloro)acetates. For comparison, the heats of formation have been calculated for all unbranched dodecanols and also for their acetates, benzoates and (trichlor)acetates. Enthalpies of reaction were estimated for all considered compounds taking into account the corresponding acid chlorides, one molecule of pyridine and the generation of pyridinium hydrochloride. It was shown that, generally, the reactivity of the dodecanols is higher than that of unsubstituted and substituted glucose. The results are discussed with regard to preparative application. |
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