The name is also used in organic chemistry for the trivalent functional group B(O−)3, or any compound (ester) that contains it, such as triethyl orthoborate B(OC2H5)3.

Simple bonding theories point to the trigonal planar structure.

Some compounds termed orthoborates do not necessarily contain the trigonal planar ion.

For example, gadolinium orthoborate GdBO3 contains the planar [BO3]3− ion only a high temperatures; otherwise it contains the polyborate anion [B3O9]9−.

In particular, these reactions include the condensation of tetrahydroxoborate with cis-vicinal diols such as mannitol, sorbitol, glucose and glycerol, to form relatively stable anion esters.