Preparation and 13C NMR spectroscopy of uniform oligopropylene glycols

✍ Scribed by C. Campbell; F. Heatley; G. Holcroft; C. Booth

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 491 KB
• Volume: 25
• Category: Article
• ISSN: 0014-3057
• DOI: 10.1016/0014-3057(89)90051-7

✦ Synopsis

Samples of di-, tetra-and octapropylene glycols which are uniform in chain length have been prepared and studied by ~3C NMR spectroscopy, with CH and CH 2 subspectra obtained by the DEPT technique. A pure sample of the head-to-head isomer of dipropylene glycol was prepared, but other samples were mixtures of regioisomers. All the resonances of the head-to-tail and the head-to-head isomers of dipropylene glycol were assigned, as well as a number of resonances of the higher oligomers, including those due to carbons adjacent to hydroxyl end groups. Overall structural parameters were determined, i.e. the fraction of secondary hydroxyl ends, the fraction of interior CH groups in head-to-head placements, and the fraction of CH 2 groups in tail-to-tail placements. A reactivity ratio for condensation of secondary vs primary end groups was also determined.