Donor number

In chemistry a donor number or DN is a qualitative measure of Lewis basicity. A donor number is defined as the negative enthalpy value for the 1:1 adduct formation between a Lewis base and the standard Lewis acid SbCl5 (antimony pentachloride), in dilute solution in the noncoordinating solvent 1,2-dichloroethane with a zero DN. The units are kilocalories per mole for historical reasons.[1] The donor number is a measure of the ability of a solvent to solvate cations and Lewis acids The method was developed by V. Gutmann in 1976.[2] Likewise Lewis acids are characterized by acceptor numbers.

Typical solvent values are:

* acetonitrile 14.1 kcal/mol (59.0 kJ/mol
* acetone 17 kcal/mol (71 kJ/mol)
* methanol 19 kcal/mol (79 kJ/mol)
* dimethylformamide (DMF) 26.6 kcal/mol (111 kJ/mol)
* dimethyl sulfoxide (DMSO) 29.8 kcal/mol (125 kJ/mol)
* ethanol 31.5 kcal/mol (132 kJ/mol)
* pyridine 33.1 kcal/mol (138 kJ/mol)
* triethylamine 61 kcal/mol (255 kJ/mol)

References

1. ^ Françoise Arnaud-neu, Rita Delgado, and Sílvia Chaves (2003). "Critical evaluation of stability constants and thermodynamic functions of metal complexes of crown ethers". Pure Appl. Chem. 75 (1): 71–102. doi:10.1351/pac200375010071.
2. ^ V. Gutmann, Coord. Chem. Rev., 18 (1976) 225

External links

* International Union of Pure and Applied Chemistry. "donor number". Compendium of Chemical Terminology Internet edition.

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