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Issue 5, 2006
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Polyurethanes with pendant hydroxy groups: polycondensation of 1,6-bis-O-phenoxycarbonyl-2,3∶4,5-di-O-isopropylidenegalactitol and 1,6-di-O-phenoxycarbonylgalactitol with diamines

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Abstract

1,6-Bis-O-phenoxycarbonyl-2,3∶4,5-di-O-isopropylidenegalactitol (5) and 1,6-di-O-phenoxycarbonylgalactitol (6) were prepared from galactaric acid in four and five steps, with overall yields of 76% and 72%, respectively. These AA type monomers were reacted with α,ω-diamines (H2N–(CH2)x–NH2; x = 2–10 and 12) as BB type monomers in a polycondensation reaction to result in polyurethanes with four protected hydroxy groups PiG2-12 or polyurethanes with four free hydroxy groups PG2-6 per repeating unit. The polyurethanes of the PiG-series were transformed by hydrolysis into polyurethanes with four free hydroxy groups per repeating unit PaG2-6. As shown by 1H NMR spectroscopy, the polyurethanes of the PG series and of the PaG series differ in their microstructure: the polymers of the first series has urethane groups with primary and secondary carbon atoms adjacent to the urethane group, while the polymers of the second series have only primary carbon atoms adjacent to the urethane group. The molecular weights of the polyurethanes, as determined by means of gel permeation chromatography in dimethylacetamide–LiCl, are in the range of 15 000 to 63 000 for the PiG and the PaG series and 15 000 to 36 000 for the PG-series with polydispersity indices of about 1.6. The thermal stability of the polyurethanes was studied by means of TGA, the polyurethanes with protected hydroxyl groups being more stable than those with free hydroxy groups. The polyurethanes of the PiG series are semi-crystalline materials with melting points between 160 and 167 °C and glass transition temperatures between 59 and 78 °C. The polyurethanes of the PG and the PaG series show glass transition temperatures of 44 to 74 °C; no melting transition is observed before decomposition starts at about 180 °C.

Graphical abstract: Polyurethanes with pendant hydroxy groups: polycondensation of 1,6-bis-O-phenoxycarbonyl-2,3∶4,5-di-O-isopropylidenegalactitol and 1,6-di-O-phenoxycarbonylgalactitol with diamines

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Publication details

The article was received on 09 Jan 2006, accepted on 28 Feb 2006 and first published on 14 Mar 2006


Article type: Paper
DOI: 10.1039/B600254D
Citation: Green Chem., 2006,8, 467-478
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    Polyurethanes with pendant hydroxy groups: polycondensation of 1,6-bis-O-phenoxycarbonyl-2,3∶4,5-di-O-isopropylidenegalactitol and 1,6-di-O-phenoxycarbonylgalactitol with diamines

    G. Prömpers, H. Keul and H. Höcker, Green Chem., 2006, 8, 467
    DOI: 10.1039/B600254D

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