Which functional groups would form hydrogen bonds with neighbouring molecules?

1 Answer
Sep 16, 2015

Any functional group that has these can hydrogen-bond with neighboring molecules:

  • #"C"="O"# (hydrogen-bond acceptor)
  • #"C"-"O"-"C"# (hydrogen-bond acceptor) [some]
  • #"C"-"NR""# (hydrogen-bond acceptor)
  • #"C"="NR"# (hydrogen-bond acceptor)
  • #"C"-"OH"# (hydrogen-bond donor AND acceptor)
  • #"C"-"NH"# (hydrogen-bond donor AND acceptor)
  • #"C"="NH"# (hydrogen-bond acceptor AND donor)
  • #"C"-="N"# (hydrogen-bond acceptor)

Any lone electron pairs present on the oxygen or nitrogen in the carbonyl, ether, the hydroxyl, the amino, the imino, and the nitrile groups above are hydrogen-bond accepting, while the hydrogens on the hydroxyl, amino, and imino groups are hydrogen-bond donating.

That means these parts of these functional groups count:

  • ketone (#"C"="O"#)
  • aldehyde (#"C"="O"#)
  • alcohol (#"C"-"OH"#)
  • carboxylic acid (#"C"="O"#, #"C"-"OH"#)
  • ester (#"C"="O"#, #"C"-"O"-"C"#)
  • amine (#-"N"-"H"#, #-"N"-"R"#)
  • imine (#="N"-"H"#, #="N"-"R"#)
  • amide (#"C"="O"#, #-"N"-"H"#, #-"N"-"R"#)
  • imide (#"C"="O"#, #="N"-"H"#, #="N"-"R"#)
  • nitrile (#"C"-="N"#)
  • amino acid (amine + carboxylic acid)

And any other functional groups that contain those.