Phys. Chem. Chem. Phys., 2005, 7

Additions and corrections

Alcohol tracer diffusion, density, NMR and FTIR studies of aqueous ethanol and 2,2,2-trifluoroethanol solutions at 25 °C

Kenneth R. Harris,*a Paula J. Newitt,ab and the late Z. J. Derlackic

a School of Physical, Environmental and Mathematical Sciences, University College, University of New South Wales, Australian Defence Force Academy, Canberra, ACT 2600, Australia; E-mail: k.harris@adfa.edu.au
b Faculty of Science, Australian National University, Canberra, ACT 0200, Australia
c Formerly of the Atomic and Molecular Physics Laboratory, Research School of Physical Sciences and Engineering, Australian National University, Canberra, ACT 0200, Australia

J. Chem. Soc., Faraday Trans., 1998, 94, 1963 (DOI: 10.1039/a802567c). Amendment published 8th November 2005

The NMR spin-echo results listed in Table 4 for the intra- (self-) diffusion coefficients of 2,2,2-trifluoroethanol (TFE) in water–TFE at 25 oC are incorrect and should be increased by a factor of 12.9%. The infinite-dilution value given in the text was obtained by Taylor dispersion and is unchanged. New values for the fit of the diffusion coefficients to eqn. (6) are given below in a revised Table 5. The discussion is unaffected, as it is the limiting value that appears in Fig. 8.

Table 5 Limiting diffusion coefficients and coefficients of eqn. (6), i
  Water–TFE
x
2D/10–9 m2 s–1 1.122 11 1.129 75
1D/10–9 m2 s–1 0.675 88 0.690 32
2 –0.912 28 –0.867 16
3 –1.665 68 –0.730 63
4 –0.898 20  
5 –1.908 90  
Standard deviation/10–9 m2 s–1 0.016 0.014

The error is due to the use of the magnetogyric ratio () for the proton rather than for the fluorine nucleus in the equation relating NMR spin-echo signal height, A, to the experimental parameters of 90–180o pulse-spacing, , and gradient current, I. (A0 is the unattenuated echo height, k the gradient coil calibration constant, g0 the backround magnetic gradient, D the selfdiffusion coefficient and T2 the spin-spin relaxation time.)

(1)

In making this correction we have used magnetogyric ratios given as IUPAC recommendations,1 namely H = 26.752 × 107 rad s–1 T–1 and F = 25.181 × 107 rad s–1 T–1.

Check measurements using a new sample of TFE (Aldrich, 99+%, dried over molecular sieves) yield values for the self-diffusion coefficient of 0.699 and 0.696 10–9 m2 s–1 at 25 oC using the proton resonance and 0.691 10–9 m2 s–1 using the fluorine resonance. The published fluorine resonance value, when corrected, is 0.677 10–9 m2 s–1, so there is now very good agreement within the experimental error of ±(1–2)%.

Of the eighteen citations of this paper reported by the ISI Web of Knowledge2 as at September 2005, six3–6 make direct use of the TFE intra-diffusion data. The change to the experimental values tends to improve agreement with the molecular dynamics simulations of Chitra and Smith3 for water–TFE mixtures, but to worsen that with the simulation of Iovino et al.5 for pure TFE. Agreement with the results of the simulations of Fioroni et al.4,6 is improved over most of the composition range, but is worsened at high TFE concentrations.

Acknowledgement

We are grateful to Dr M. Kanakubo for a comment that led to the detection of this error.

References

  1. R. K. Harris, E. D. Becker, S. M. Cabral de Menezes, R. Goodfellow and P. Granger, Magn. Reson. Chem., 2002, 40, 489.
  2. http://portal15.isiknowledge.com/
  3. R. Chitra and P. E. Smith, J. Phys. Chem. B, 2000, 104, 5854; R. Chitra and P. E. Smith, J. Chem. Phys., 2001, 114, 426; R. Chitra and P. E. Smith, J. Chem. Phys., 2001, 115, 5521.
  4. M. Fioroni, K. Burger, A. E. Mark and D. Roccatano, J. Phys. Chem. B, 2000, 104, 12347.
  5. M. Iovino, M. Falconi, A. Marcellini and A. Desideri, J. Pept. Res., 2001, 58, 45.
  6. M. Fioroni, M. D. Diaz, K. Burger and S. Berger, J. Am. Chem. Soc., 2002, 124, 7737.

The Royal Society of Chemistry apologises for these errors and any consequent inconvenience to authors and readers.

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