NMR studies on solution structures of methanol and ethanol saturated with CO2

T. Umecky, T. Takamuku, Tsutomu Aida, T. Makino, T. Aizawa, M. Kanakubo

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

2H and 17O NMR relaxation times, T 1(2H) and T 1(17O), and 2H NMR chemical shifts, δ(2H), in CO2-saturated CD3OD and C2D5OD solutions were measured at 313.2 K over the pressure range up to ~6 MPa. The rotational correlation times, τ r, of the CD and OD axes within CD3OD and C2D5OD molecules and the CO axis within the CO2 molecule were determined from T 1(2H) and T 1(17O), and the magnetic susceptibility-corrected chemical shifts, δ corr, were derived from δ(2H). The differences in τ r and δ corr observed between the two alcohol systems: τ r and δ corr of OD in C2D5OD, decreased rapidly with increasing CO2 concentration, while those of OD in CD3OD remained almost unchanged at mole fractions of CO2, $$ x-{\text CO-{2}} $$ x C O 2, lower than ~0.25 and then slightly decreased at higher $$ x-{\text CO-{2}} $$ x C O 2. The hydrogen bonding structure in C2D5OD was found to be gradually broken down by CO2 dissolution. On the other hand, in CD3OD, it has been revealed that the hydrogen bonding structure can persist at $$ x-{\text CO-{2}} $$ x C O 2 < ~0.25 but then collapses at higher $$ x-{\text CO-{2}} $$ x C O 2.

Original languageEnglish
Pages (from-to)1539-1549
Number of pages11
JournalJournal of Solution Chemistry
Volume43
Issue number9-10
DOIs
Publication statusPublished - 2014 Oct 21
Externally publishedYes

Keywords

  • Alcohols
  • CO
  • Chemical shifts
  • NMR
  • Relaxation times
  • Rotational correlation times

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Physical and Theoretical Chemistry

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