Table 1 H-bonding capabilities (in kilojoules per mole) of defined atoms (red) in basic functional groups calculated from water/hexadecane partition coefficients (fig. S2): R, R1, and R2 represent alkyl groups.

The H-bonding capability for oxygen atoms is the value of a lone pair (±SDs).

H-bond acceptorsH-bond donors
AtomH-bonding capabilityAtomH-bonding capability
H2O7.02 (±0.11)H2O7.02 (±0.11)
Apolar atom0Apolar atom0
AlcoholAlcohol6.6 (±0.21)
RCH2OH8.7 (±0.42)RCH2OH
RR1CHOH9.5 (±0.58)RR1CHOH6.3 (±0.20)
SerCH2OH8.1 (±0.42)CF3CH2OH10.2 (±0.45)
EtherAmide
THF: (CH2)4O8.2 (±0.22)RCH2C(=O)NHR17.6 (±0.65)
RCH2OCH2R7.2 (±0.35)C6H5C(=O)NHR17.2 (±0.86)
AldehydePhenol
RCH2CHO8.9 (±0.45)4-R-C6H4OH10.8 (±0.74)
4-RC6H4CHO7.6 (±0.26)4-NO2-C6H4OH16.9 (±0.75)
KetoneAniline
4-RC6H4COMe10.4 (±0.27)C6H5NH22.7 (±0.51)
RCH2COCH2R9.8 (±0.55)4-NO2-C6H4NH26.1 (±0.78)
Ester (O.2)Amino
4R-C6H4C(=O)OCH38.4 (±0.26)RCH2NH21.3 (±0.34)
RCH2C(=O)OCH2R9.6 (±0.47)(RCH2)2NH1.5 (±0.61)
AmideAcid
RCH2C(=O)NH214.5 (±0.62)RCH2COOH11.2 (±0.86)
RCH2C(=O)NHCH314.9 (±0.64)C6H5COOH11.5 (±1.03)
RCH2C(=O)N(CH3)215.9 (±0.22)Cl3CCOOH20.4 (±0.77)
C6H5C(=O)NH212.0 (±0.88)3NO2-C6H4COOH13.2 (±1.06)
AminoOthers
RCH2NH219.7 (±0.58)CHCl33.6 (±0.42)
(RCH2)2NH22.9 (±0.42)CHBr32.7 (±0.31)
(RCH2)3N22.8 (±0.31)RCH2NO20.85 (±0.16)
NitrileRCH2CN0.6 (±0.14)
RCH2CN18.1 (±0.36)
C6H5CN15.4 (±0.43)
Pyridine
C5H5N18.2 (±0.62)
4-CN-C4H4N12.3 (±0.64)
Others
C6H5O*H6.4 (±0.51)
Furan: C4H4O*2.9 (±0.65)
RC6H5 (pi electron)1.6 (±0.18)

*Because the two lone pairs of electrons are not identical, H-bonding capability is the value of the oxygen atom.