- Regioselective hydrolysis of diacetoxynaphthalenes catalyzed by Pseudomonas sp. lipase in an organic solvent
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Depending on the relative positions of the acetyl groups in the aromatic rings, the Pseudomonas sp. lipase-catalyzed hydrolysis of diacetoxynaphthalenes in tert-butylmethyl ether proceeds regioselectively to afford the corresponding monoacetates.
- Ciuffreda, Pierangela,Casati, Silvana,Santaniello, Enzo
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p. 317 - 321
(2007/10/03)
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- Method for preparing aromatic bischloroformate compositions
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Bischloroformate oligomer compositions are prepared by passing phosgene into a heterogeneous aqueous-organic mixture containing at least one dihydroxyaromatic compound, with simultaneous introduction of a base at a rate to maintain a specific pH range and to produce a specific volume ratio of aqueous to organic phase. By this method, it is possible to employ a minimum amount of phosgene. The reaction may be conducted batchwise or continuously. The bischloroformate composition may be employed for the preparation of cyclic polycarbonate oligomers or linear polycarbonate, and linear polycarbonate formation may be integrated with bischloroformate composition formation in a batch or continuous process.
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- Oxyfunctionalization of Hydrocarbons. 17. Acid-Dependent High Regioselectivity Hydroxylation of Naphthalene with Hydrogen Peroxide Giving 1- or 2-Naphthol
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The acid-catalyzed hydroxylation of naphthalene with 90percent hydrogen peroxide was investigated.Regioselectivity of the reaction depends on the acidity of the system and the solvent used.In anhydrous hydrogen fluoride or 70percent HF-30percent pyridine solution at -10 to +20 deg C 1-naphthol is the product formed in > 98percent selectivity.In contrast, 2-naphthol is obtained in hydroxylation in superacid (HF-BF3, HF-SbF5, HF-TaF5, FSO3H-SbF5) solution at -60 to -78 deg C in > 98percent selectivity.When 1-naphthol reacted under the latter conditions 1,5- and 1,7-dihydroxynaphthalene were obtained, while 2-naphthol gave 1,6-dihydroxynaphthalene (along with only minor amounts of 1,7-dihydroxynapthtalene).The mechanism of the reactions is discussed, contrasting electrophilic hydroxylation of naphthalene, giving predominantly 1-substitution, with reaction of protonated naphthalenes (i.e., naphthtalenium ions) with hydrogen peroxide.
- Olah, George A.,Keumi, Takashi,Lecoq, Jean Claud,Fung, Alexander P.,Olah, Judith A.
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p. 6148 - 6151
(2007/10/02)
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- Bischoloroformate preparation method with phosgene removal and monochloroformate conversion
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Aqueous bischloroformates are prepared by the reaction of a dihydroxyaromatic compound (e.g., bisphenol A) with phosgene in a substantially inert organic liquid (e.g., methylene chloride) and in the presence of an aqueous alkali metal or alkaline earth metal base, at a pH below about 8. After all solid dihydroxyaromatic compound has been consumed, the pH is raised to a higher value in the range of about 7-12, preferably 9-11, and maintained in said range until a major proportion of the unreacted phosgene has been hydrolyzed. At the same time, any monochloroformate in the product may be converted to bischloroformate.
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- Cyclic monocarbonate bishaloformates
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Cyclic monocarbonate bischloroformates are prepared by the reaction of a carbonyl halide such as phosgene with a bridged substituted resorcinol or hydroquinone such as bis(2,4-dihydroxy-3-methylphenyl)methane or bis(2,5-dihydroxy-3,4,6-trimethylphenyl)methane in the presence of aqueous alkali metal hydroxide. The cyclic monocarbonate bischloroformates may be used for the preparation of linear or cyclic polycarbonates containing cyclic carbonate structural units, which may in turn be converted to crosslinked polycarbonates.
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- Polyetherimide bisphenol compositions
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Polyetherimide bisphenols and bischloroformates are prepared by the reaction of dianhydrides or certain bisimides with aminophenols or mixtures thereof with diamines. They are useful as intermediates for the preparation of cyclic heterocarbonates, which may in turn be converted to linear copolycarbonates. The bisphenols can also be converted to salts which react with cyclic polycarbonate oligomers to form block copolyetherimidecarbonates.
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- HYDROXYLATION DES NAPHTOLS EN MILIEU SUPERACIDE
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Hydroxylation of α and β naphtols by hydrogen peroxide in SbF5-HF occurs selectively on the non-phenolic ring, the electrophile reacting on the C-protonated substrate.
- Jacquesy, Jean-Claude,Jouannetaud, Marie-Paule,Morellet, Guy
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p. 3099 - 3102
(2007/10/02)
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- Method for preparing adduct of butadiene polymer or copolymer and α, β-ethylenically unsaturated dicarboxylic acid compound
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In a method for preparing an adduct of (A) a butadiene lower polymer or butadiene lower copolymer and (B) a α,β-ethylenically unsaturated dicarboxylic acid compound, said method is characterized in that said (A) and (B) are caused to react in the presence of one or more compounds selected from (C) p-phenylenediamine derivatives, catechol derivatives, pyrogallol derivatives, N-nitrosamines, quinoline derivatives and naphthol derivatives, thus serious increase of the viscosity of said adduct in the addition reaction can be prevented.
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