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Boric acid derivatives

The first in this series to be reported was 4-oxoisoxazoline-3,5-dicarboxylic acid diethyl ester, which was formed by the reaction of nitrous acid on diethyl acetonedicarboxylate in 1891. Quilico described a number of syntheses in his 1962 review and the most general include the reaction of hydroxylamine and a-hydroxy-(or acetoxy)- 3-diketones and the conversion of 4-isoxazolediazonium salts to the hydroxy moiety (62HC(17)1, p. 3). Additional syntheses reported were the oxygenation of a 4-boric acid derivative (67JOM(9)l9) and peroxide oxidation of a 4-nitro-2-isoxazoline (Scheme 151) (79ZOR2436). [Pg.106]

The Si-O-B fragment can be formed from different starting materials that generally include chlorosilanes or silanols and boron halides or boric acid derivatives. For the preparation of the cyclic six-, eight-, ten- and twelve-membered borasiloxanes 83-89 four synthetic approaches are known so far, starting from either... [Pg.24]

Identical conditions for the synthesis of a-hydroxyalkylphosphines and for borylation make it possible to combine the formation of a-hydroxyalkylphosphines and their interaction with boric acids derivatives. As a rule, in all the examples cited below, there is one single course of reaction without any by-products. Thus, diphenylboryloxyalkyl(imidoyl)phos-phines (114) [Eq. (71)], ammonium 1,3,2,5-dioxaborataphosphorinanes... [Pg.90]

Borate esters react with the lithium compound to yield (r/ -cp)Fe(r 5-cp-B(OR)2), which can be hydrolyzed to produce (//5-cp)Fe(r/5-cp-B(OH)2). This compound will undergo many reactions that lead to additional ferrocene derivatives. For example, the reaction with CH3ONH2 produces the aminoferro-cene. The boric acid derivative will react with AgO in a coupling reaction that produces the "diferrocene" shown as... [Pg.769]

Another part of the substance is melted in a platinum crucible with nitre and sodium carbonate, the mass obtained being dissolved in water any insoluble residue may contain especially ferric oxide. The solution is acidified with hydrochloric acid, boiled for a long time with alcohol and evaporated almost to dryness, the residue being taken up in water and filtered from any silica which separates the filtrate is tested for the metals, phosphoric acid and boric acid (derivable as an impurity from the manufacturing processes) by the ordinary qualitative methods. [Pg.395]

Boric acid derivatives are reported to catalyse lactone formation from cyclic ketones using hydroperoxide oxidants.278... [Pg.127]

Sultones were the earliest anionic stabilisers used in cyanoacrylates but fell from favour because of their potential carcinogenicity. Chelates of boric acid derivatives with polyhydroxy compounds also were considered as anionic inhibitors. Anionic inhibitors are normally added at concentrations between 0.001 and 0.01% depending on the application. [Pg.170]

The homopolymerization of boric acid derivatives catalyzed by palladixam has very recently appeared by two research groups [10]. This polymerization technique employs cross-coupling chemistry of boric acids developed by Suzuki and coworkers [4]. The yields of the pure carbon pol3nners were above 89% (eq 6) [10b]. [Pg.153]

One method to reduce the volatility of sulfur dioxide is to complex it with imidazole and then add the complex to the adhesive. Chelates of boric acid derivatives with polyhydroxy compounds have also been prepared as anionic polymerization inhibitors. The chelates can be preformed or prepared in situ by adding the boric acid compound and the polyhydroxy compound to the adhesive. Sulfamides have been used to stabilize cyanoacrylates. The sulfamides (24) in question are prepared by reacting sulfuryl diisocyanate (23) with active hydrogen compounds such as carboxylic acids, as shown in Eq. (7). ... [Pg.265]

These results show that the aqueous dilutions can be contaminated both with bacteria and also with yeasts and moulds. The multiplication (increase in the number of organisms per volume unit) of the bacteria can be controlled better by the boron derivatives than that of yeasts and moulds. Through the addition of preservative, e.g. Grotan Forte, the mix can be kept visually practically free of organisms. Evaluation of the individual results also shows that by adding the preservative the solution can still be well preserved even as the level of the boric acid derivative declines. [Pg.210]

We were provided with the following data for the coolants formulated with boric acid derivatives ... [Pg.210]

From the results presented earlier, it can be seen that the multiplication of bacteria can be completely or at least partially prevented by boric acid derivatives, depending on the boron concentration. However, the test results and practical experience also show that this is not possible with yeasts and moulds. [Pg.211]

Hydrolysis protection is significant for poiycarbonate and poiycarbonate blends, such as PC/ABS blends. Even traces of bases and/or saponifiable chlorine will destroy polycarbonate and with it the entire system. Consequently, care must be taken to avoid agents that trigger PC hydrolysis in the production of blends. Phosphites and boric acid derivatives have proven especially effective hydrolysis stabilizers. They enable the processing of blends at high temperatures without triggering scission or hydrolysis reactions. [Pg.299]

A route to 3,4-dihydroxy-l-alkenes (56) (Scheme 23) is based on the lithiation of allylsilyl ethers. Separation of cw-l,2-diols from mixtures, and the protection of such functionality. have been achieved by selective coupling to a polymeric boric acid derivative (57). An improved procedure for the Ti reduction of 1,2-diols to alkenes, using Rieke active Ti powder, has been published, and avoids the unpredictability of an earlier method. [Pg.172]

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. [Pg.27]


See other pages where Boric acid derivatives is mentioned: [Pg.13]    [Pg.84]    [Pg.103]    [Pg.24]    [Pg.209]    [Pg.297]    [Pg.32]    [Pg.55]    [Pg.177]    [Pg.269]   
See also in sourсe #XX -- [ Pg.297 , Pg.298 , Pg.340 , Pg.341 ]




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