Raman study of aqueous monoborate-polyol complexes. Equilibriums in the monoborate-1,2-ethanediol system

Abstract

Raman spectra have been obtained of aqueous solutions containing B (0H)a-and various polyols, including 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, and 1,2,3-propanetriol. Several spectral features arise which can be explained only on the basis of the chelate formation originally postulated by Hermans; there is no evidence of polymerization in the concentrated solutions examined. Assignments are presented for the simplest five-membered (1,2-ethanediol) and six-membered (1,3-propanediol) borate chelates and comparisons made with related ring systems. Spectral changes caused by ring substitution are briefly discussed. il band assigned t o B-0 ring stretching provides the most reliable indication of ring size, having an average position of 766 cm-I for five-membered and ca. 720 cm-' for six-membered chelates. Through quantitative intensity measurements on the aqueous 1,2-ethanediol-B(OH)4-system, it is established that 1 : 1 and 2 : 1 (diol: boron) complexes exist in concentrated solution; a t 30°, the overall equilibrium molarity quotients are p1 = 1.8 =k 0.2 M-l and 02 = 0.65 =I= 0.15 M F 2 .

Boron removal from aqueous solutions by activated carbon impregnated with salicylic acid

“…The second stage in which formation between -COOH and -OH groups with boric acid or borate ion, being a six-member lacton is a chemisorption. Chemical reaction here were confirmed with literature data, too [20,21]. Also, that Arrhenius graph gave an activation energy of 54.85 kJmol −1 verified that the process was a chemisorption [28].…”

“…The formation of anionic complexes have been confirmed by Raman, C 13 and B 11 spectroscopy [18,19]. Further, Oertel's Raman datas have given direct evidence for chair conformation for 1,3-diol-borate complex [20]. Van Duin et al [21] have established a "charge rule" for determining pH stability of the different complexes.…”

Organic biomolecules bind to phosphate through borate linkages in aqueous solutions

“…The broad band at 613 cm −1 and the new band at 744 cm −1 can be assigned to B-O-P vibrations 31,46 and those of the 5-membered borate ring, respectively. 30 The other bands observed at ∼920 cm −1 and 1889 cm −1 were assigned to ν a (PO 3 ) (Q 1 ) and C=O stretching of ascorbic acid. 47 The 31 P MAS NMR spectra shown in Figure 6 displayed a Q 1 B signal at ca.…”

“…650 cm −1 and the new band at 743 cm −1 may be respectively assigned to B-O-P vibrations 31,46 and those of the 5-membered borate ring. 30 The other peaks observed referred to characteristic Raman signals of citric acid. 47 The 31 P MAS NMR and 11 B NMR spectra displayed similar patterns as recorded for 2 with small changes in the chemical shift values due to the structural differences between ascorbic and citric acids.…”

Polarographic studies of the interaction of boric acid with 1-hydroxy- and 1,2-dihydroxy-9,10-anthraquinones and -anthrahydroquinones

“…The formation of chelated esters of boric acid and 1,2-diols is well-known (1)(2)(3). The rings in the cyclic esters are limited to five or six atoms, and the boron: diol ratio is usually 1 : 1 or 1 : 2.…”