Triethanolamine borate ester

U.S. Borax Research Corp., Anaheim, California, markets several borate esters under the trademark BORESTER. These include triethanolamine borate (BORESTER 20), tricresyl borate (m- and p-isomers) (BORESTER 8), and the biborate (4) (BORESTER 7). Whereas the chemical name for (4) is given in Table 1, it is commonly referred to as trihexylene glycol biborate [26545-48-2] and is prepared by the reaction of two moles of boric acid and three moles of hexylene glycol. 

For the most part boric acid esters are quantitated by hydrolysis in hot water followed by determination of the amount of boron by the mannitol titration (see Boron compounds, boric oxide, boric acid and borates). Separation of and measuring mixtures of borate esters can be difficult. Any water present causes hydrolysis and in mixtures, as a result of transesterification, it is possible to have a number of borate esters present. For some borate esters, such as triethanolamine borate, hydrolysis is sufftciendy slow that quantitation by hydrolysis and titration cannot be done. In these cases, a sodium carbonate fusion is necessary. 

The addition of allylic boron reagents to carbonyl compounds first leads to homoallylic alcohol derivatives 36 or 37 that contain a covalent B-O bond (Eqs. 46 and 47). These adducts must be cleaved at the end of the reaction to isolate the free alcohol product from the reaction mixture. To cleave the covalent B-0 bond in these intermediates, a hydrolytic or oxidative work-up is required. For additions of allylic boranes, an oxidative work-up of the borinic ester intermediate 36 (R = alkyl) with basic hydrogen peroxide is preferred. For additions of allylic boronate derivatives, a simpler hydrolysis (acidic or basic) or triethanolamine exchange is generally performed as a means to cleave the borate intermediate 37 (Y = O-alkyl). The facility with which the borate ester is hydrolyzed depends primarily on the size of the substituents, but this operation is usually straightforward. For sensitive carbonyl substrates, the choice of allylic derivative, borane or boronate, may thus be dictated by the particular work-up conditions required. 

Chelating agents such as triethanolamine borate also behave as latent catalysts at elevated temperatures. Other boron-containing compounds, cadmium or zinc bromide dieth-ylenetriamine, and salts of aluminum acetoacetic ester have also been suggested as curing agents for high-temperature epoxy adhesives. 

The co-use of furfuryl alcohol with a triazine derivative or triethanolamine and a quaternary borate ester-salt catalyzed the polymer-... 

CAS 283-56-7 EINECS/ELINCS 206-003-5 Synonyms Boric acid, tris (2-aminoethyi) ester Ethanol, 2,2, 2"-nitrilotri-, cyclic borate 2,2, 2"-Nitriloethyl borate Triethanolamine borate... 

Aq. Na-tetraphenylhorate (Kalignost) added to aq. triethanolamine borate, then dil. acetic acid added to pH 6 triethanolamine tetraphenylborate. Y ca. 100%.—The stability of the ester is caused by a semipolar N -B-bond which is eliminated by addition of tetraphenylborate. R. Neu, Arch. Pharm. 29A, 721 (1961). 

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