Gutmann acceptor and donor numbers

The Gutmann Acceptor- (AN) and Donor Number (DN) are measures of the strength of solvents as Lewis acids or bases.
The Acceptor Number is based on the 31P-NMR chemical shift of triethylphosphine oxide in the solvent.
The Donor Number is based on the heat of reaction between the compound dissolved in CH2ClCH2Cl and SbCl5, and is therefore a 'solute' rather than a 'solvent' scale. Because SbCl5 is decomposed by protic compounds, e.g. alcohols, the Donor Numbers for these have to be determined by indirect methods.

The Acceptor Number is a measure of hydrogen bond acidity and correlated with other hydrogen bond acidity scales such as → Dimroth-Reichardt ET (→ ET vs AN) and → Swain Acity (→ Acity vs AN). Correlation with → Kamlet-Taft α and → Catal├ín SA is weaker.
The Donor Number is correlated with → Kamlet-Taft β (→ β vs DN).

See → "The donor-acceptor approach to molecular interactions" by V. Gutmann, Plenum Press, New York and London (1978), and →Lewis donor strength for scales of Lewis bases.

Note: AN values in parenthesis are estimated from the corresponding Dimroth-Reichardt ET-values.

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NameFormulaAcceptor number
AN
Donor number
DN
🏷 Tag
quinolineC9H7N(12.2)32.0aromatic; heteroaromatic;
selenium oxychlorideH2Cl2OSe12.2
styreneC8H8(3.5)5.0alkene; aromatic;
sulfolaneC4H8O2S19.214.8
sulfuryl chlorideCl2O2S0.1
tert-butyl acetateC6H12O235.9ester;
tetrachloromethaneCCl48.60.0halo;
tetrahydrofuranC4H8O8.020.0ether;
thionyl chlorideCl2OS0.4
tolueneC7H8(1.8)0.1aromatic;
tri(azetidin-1-yl)phosphine oxideC9H18N3OP43.0
tributyl phosphateC12H27O4P9.923.7
tributylamineC12H27N(0.0)50.0amine;
trichloromethaneCHCl323.14.0halo;
triethyl phosphateC6H15O4P(16.5)26.0
triethylamineC6H15N1.461.0amine;
triethylenephosphoramideC6H12N3OP50.0
trifluoroacetic acidC2HF3O2105.3halo; carboxylic_acid;
trifluoromethanesulfonic acidCHF3O3S129.1
trimethyl phosphateC3H9O4P16.323.0
trimethylureaC4H10N2O29.3
trioctylphosphine oxideC24H51OP33.8
tripyrrolidinophosphine oxideC12H24N3OP47.2
waterH2O54.818.0