Raman spectroscopic evidence for the formation of B(OH)_n(OR)_(3-n) (n = 0,1,2; R=CH3, C2H5 or CH(CH3)2) from boric acid in lower alcohol solutions

摘要

Raman spectroscopy has been used to study the boron species in methanol, ethanol or 2-propano! solutions of boric acid. Raman bands are observed at about 814, 773, and 728 cm~(-1) for methanol solutions of boric acid in the wavenumber range from 900 to 700 cm~(-1). The three Raman bands were assigned on the assumption that boric acid reacts with methanol and produces methyl borates, B(OH)2(OCH3), B(OH)(OCH3)2, and B(OCH3)3, which are considered to have bands at 814, 773, and 728 cm~(-1), respectively. For ethanol solutions of boric acid, Raman bands were detected at around 783,754, and 726 cnrr] and assigned to B(OH)2(OC2H5), B(OH)(OC2H5)2, and B(OC2H5)3, respectively. Moreover, Raman bands were sighted at about 788, 762, and 732 cm~(-1) for 2-propanol solutions of boric acid and attributed to B(OH)2(OCH(CH3)2), B(OH)(OCH(CH3)2)2, and B(OCH(CH3)2)3, respectively.