I appreciate Crutchfield's comments, particularly because it is desirable to ensure to the extent possible that HazMat personnel do not overreact to any presumed hazards that a substance might possess. In fact, because of this concern, the CLIP in question specifically identifies boric acid as a mild oxidizer (1). (Consequently, I must disagree with Crutchfield's worry that as a consequence of reading the CLIP on acetic anhydride some HazMat person might deduce that it is instead a strong oxidizer.)

As to the products of the reduction of boric acid, I have no specific information; but we all, including Crutchfield, I presume, know that using heats of formation to predict that a chemical reaction will or will not occur often leads to error. The correct procedure is to calculate the change in free energy that would be associated with the process under the conditions that exist, which is different from using free energies of formation, of course. (Enough elementary thermo!)

Hypothesizing, I offer hypoboric acid, BH₃OH, or one of the boron suboxides, perhaps BO, or its dimer or tetramer as possible products from the reduction of boric acid. There are other candidates as well, of course. For further detailed information, carry out the tedious thermodynamic (and kinetic) exercises, or see the original German literature as cited in Chem. Eng. News 1973, 51 (34), 42 (2).

Literature Cited

1. Young, J. A. J. Chem. Educ. 2001, 78, 1176.

2. Chem. Eng. News 1973, 51 (34), 42