Boric acid ester

The ionization of boric acid is enhanced in solutions containing carbohydrates (143). This effect is variable, apparently depending upon the individual complexing ability of the sugar. Khym and Zill (144) have used this effect to separate sugars by removing their borate complexes from ion-exchange resins in columns by differential elution with acid developers 

Levene, Hexosamines and Mucoproteins. Longmans, Green, London, 1925 M. Stacey, Advances in Carbohydrate Chem. 2,161 (1946). 

Crystalline esters of alditols and aldoses completely esterified with phenylboronic acid, C6H5B(OH)2, have been reported IJfi). 

In 1846 the first boric acid esters were prepared by reacting aUphatic alcohols and boron trichloride (1). The chemistry and properties of boric acid esters from that first paper through 1961 have been extensively reviewed (2). Short reviews were pubUshed in 1964, 1978, and two in 1980 (3,4). 

The general formula for boric acid esters is B(OR)2. The lower molecular weight esters such as methyl, ethyl, and phenyl are most commonly referred to as methyl borate [121 -43-7] ethyl borate [130-46-9J, and phenyl borate [1095-03-0] respectively. Some of the most common boric acid esters used in industrial appHcations are Hsted in Table 1. The nomenclature in the boric acid ester series can be confusing. The lUPAC committee on boron chemistry has suggested using trialkoxy- and triaryloxyboranes (5) for compounds usually referred to as boric acid esters, trialkyl (or aryl) borates, trialkyl (or aryl) orthoborates, alkyl (or aryl) borates, alkyl (or aryl) orthoborates, and in the older Hterature as boron alkoxides and aryloxides. CycHc boric acid esters, which are trimeric derivatives of metaboric acid (HBO2), are known as boroxines (1). 

Compound name CAS Registry Number Molecular formula Mp, °C Bp, °C b 

Triphenyl borate has been reported to melt at temperatures from 38 to 146°C. Most values are in the range of 80—90°C. At 2.3 kPa (17 mm Hg). 

Most reported boric acid esters are trialkoxy or triaryloxy boranes. The esters range from colorless low boiling Hquids to soHds that possess high melting points. Boric acid esters usually have an odor similar to the hydroxy compound from which they are derived. A more complete description of the physical 

---

PORONCOMPOUNDS - BORIC ACID ESTERS] (Vol 4) a,g,g-Trimethyl-g-butyrolactone [2610-96-0]... 

---