Catechol, boric acid complex

Catechol, boric acid complex, IV, 194 effect on conductivity of boric acid, IV, 191... 

The proof that the formation of certain complexes is involved in the changes of conductivity is furnished by the investigations of Hermans. He established that the compound of catechol, boric acid and potassium... 

Earlier fluorometric methods for analysis of urinary free catecholamines have been replaced by HPLC methods that allow selective quantitation of epinephrine, norepinephrine, and dopamine. Preliminary extraction of urine is stid required and numerous preanalytical cleanup techniques are available. An alumina extraction procedure is typically coupled with ion-exchange or adsorption chromatography. Alumina pretreatment usually involves a batch extraction technique in which catechols are first adsorbed at pH 8.6 and then eluted with boric acid, which forms a complex with cis-diol groups. Purification on boric acid affinity gels provides an alternative procedure for selective adsorption of catecholamines. 

Catechol violet (I) forms colored complexes with many ions but only the complexes with boric acid, germanium, niobium and tantalum are unaffected by EDTA. At pH 6-7 boric acid forms a reddish complex, germanium purple and niobium and tantalum blue-violet. At pH 1 and in the presence of sufficient EDTA, only tantalum forms a colored complex. ... 

Test with boric acid-catechol violet complex... 

The red-violet complex of boric acid and catechol violet reacts selectively with yttrium salts to form a blue complex of yttrium and catechol violet. 

Complex of catechol violet with boric acid 5 610... 

Boron-Oxygen Compounds. Studies of the formation of chelate complexes of boric acid and of boronic acids continue to appear. A two-stage process for the reaction between boric acid and salicylic acid is observed. Studies on a range of substituted catechols are interpreted as indicating a transition state in which proton transfer is important. 

Catechol groupings react with boric acid or its salts in aqueous solution to form cyclic borate complexes. These are not methylated by diazomethane and this forms the basis of an interesting preparation [5] of the flavonol rhamnetin (8) from rutin (7). 

Boric complexes with p5T ocatechol and gaUic acid have been reported (43, 48). The stability constant of boric-catechol-3,5-disulphonic acid has been determined potentiometrically (56). Borate inhibits tyrosinase activity by forming 1 1 or 1 2 complexes with the substrates catechol or dopa. The stability constants of these complexes have been determined spectrophotometrically and are in the order of 5.3 X 10 and 6.7 X 10- , respectively (73). 

Ndsdnen, R. Complex formation between boric and catechol-3,5-disulphonic acid. Suomen Kemistilehti B 33, 1 (1960). 

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See also in sourсe #XX -- [ ]

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