Boric acid esters trimethyl borate

Boric-acid ester n. One of a family of flame retardants for plastics, etc. and plasticizers. Examples are the trimethyl, tri-n-butyl, tricyclohexyl, and tri-p-cresyl borates. Kidder RC (1994) Handbook of fire retardant coatings and fire testing services. CRC Press, Boca Raton, FL. 

As shown in Fig. 2.19, starting from o-cresol 2.2.16, with NBS ortho-bro-mination and then MOM protection of phenolic hydroxyl group, compound 2.2.17 was obtained in two steps with 55 % overall yield. Reacted in butyl lithium and then quenched with trimethyl borate, arylboronic acid ester was obtained. The boric acid ester was in situ hydrolyzed to boric acid compound 2.2.18 with diluted HCl to give 45 % yield. Compound 2.2.18 was reacted with lead (IV) acetate/ mercury (II) acetate to convert the boric acid into lead reagent 2.2.19. Without... 

In the aromatic and heterocyclic series, no hydroboration is possible. In general, an organoalkali intermediate is prepared by metalation or halogen/metal permutation before being treated with a boric acid derivative such as trimethyl borate or, because of its cleaner reaction, triisopropyl borate. The resulting ate complex sets free the oxidizable boronate upon addition of water or a stoichiometric amount of diluted hydrochloric acid. The boronate can be accessed directly when fluorodimethoxyborane is used instead of a boric acid ester as the adduct eliminates lithium fluoride spontaneously. The oxidation relies on the same procedures and principles as outlined above. 

Trimethoxyborane ALDRICH Trimethyl borate Boric acid, trimethyl ester (8,9) (121-43-7)... 

Bromo-3,4,5-trifluorobenzene Benzene, 5-bromo-1,2,3-trifluoro- (13) (138526-69-9) Trimethyl borate Boric acid, trimethyl ester (8,9) (121-43-7)... 

Unprotected aldoses and ketoses can be reduced to afford alditols while aldonolactones can be reduced to give either aldoses or alditols. The reagent of choice for reduction to alditols is sodium borohydride since it is both cheap and convenient to use. The reduction is carried out under mild conditions at room temperature in an aqueous solution. Sodium borohydride is stable in water at pH 14 while it reacts with the solvent at neutral or slightly acidic pH, but at a slower rate than the rate of carbonyl reduction. In some cases, the product will form esters with the generated boric acid. These borate complexes can be decomposed by treatment with hydrochloric acid or a strongly acidic ion-exchange resin and the boric acid can be removed in the work-up as the low boiling trimethyl borate by repeated co-evaporation with methanol at acidic pH [155]. 

Synonyms Boric acid, trimethyl ester Boron methoxide Methyl borate Trimethoxyborane Trimethoxyborine Trimethoxyboron... 

The boron compound can be a borane (R jB), a borate ester (R -B(OR)2), or a boric acid (R -B(OH)2), where R is an allqrl, alkenyl, or aryl group. Boranes are made using hydroboration of alkenes or allgmes. Borates are made from aryl or alkyl lithium compounds and trimethyl borate. 

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