- Selectivity in the photo-Fenton and photocatalytic hydroxylation of biphenyl-4-carboxylic acid and derivatives (viz. 4-phenylsalicylic acid and 5-phenylsalicylic acid)
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The selectivity of hydroxylation of the distal rings of 4-phenylbenzoic acid, 4-phenylsalicylic acid, and 5-phenylsalicylic acid were determined using partial TiO2-mediated photocatalytic degradation and photo-Fenton conditions. This separation of the binding site from the phenyl group being hydroxylated allows a less-biased evaluation. The hydroxylation regiochemistry behaves as qualitatively expected for an electrophilic reaction, given the assumption that 4-carboxyphenyl is a slightly electron-withdrawing substituent. Selectivity for hydroxylation of the distal phenyl in 4- and 5-phenylsalicylic acid is reversed, due to the reversal of the electronic demand, while adsorption to the TiO2 surface is assumed to be analogous for the two structures. Copyright
- Hathway, Timothy,Chernyshov, Deborah Lipman,Jenks, William S.
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p. 1151 - 1156
(2013/01/09)
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- Palladium(II)-catalyzed sequential hydroxylation-carboxylation of biphenyl using formic acid as a carbonyl source
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(Equation Presented) A simultaneous hydroxylation-carboxylation of biphenyl occurred to give 4′-hydroxy-4-biphenylcarboxylic acid, which has wide potential application as a polyester monomer.
- Shibahara, Fumitoshi,Kinoshita, Shinsuke,Nozaki, Kyoko
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p. 2437 - 2439
(2007/10/03)
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- Mechanism of Alkaline Hydrolysis of Some HO-π-COOAr Acyl Derivatives
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To gain knowledge on the role played by the nature of the bridge interposed between hydroxyl and carbonyl groups in esters of the title type, in principle able to hydrolyze through dissociative pathways via the conjugate base of the substrate (E1cB mechanism), we have studied the alkaline hydrolyses of 2,4-dinitrophenyl esters in which the π-system is a biphenyl, azobenzene, benzylide-neaniline, or stilbene skeleton. Kinetic data, such as reactivity comparisons and Arrhenius parameters, show that these substrates react through the usual, associative, BAc2 mechanism. This outcome is discussed and interpreted from both structural and energetic standpoints. The data suggest that a value of 0.0 is the most appropriate assignment of the σp value for the benzylidenamino substituent (C6H5CH=N-).
- Cevasco, Giorgio,Thea, Sergio
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p. 5422 - 5426
(2007/10/03)
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- Process for the preparation of 4'-hydroxybiphenyl-4-carboxyl acid
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A process for the preparation of 4'-hydroxybiphenyl-4-carboxylic acid by reacting a cyclohexanone-4-carboxylic acid compound with phenol in the presence of an acid catalyst, and then subjecting the resulting 4,4-bis(4-hydroxyphenyl)cyclohexanecarboxylic acid compound to decomposition and dehydrogenation reactions in the presence of a base and a dehydrogenation catalyst. The aforesaid cyclohexanone-4-carboxylic acid compound is obtained by catalytically hydrogenating a 4-hydroxybenzoic acid compound in a secondary alcohol or tertiary alcohol solvent, and the reaction mixture thus obtained is directly used for the reaction with phenol.
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- Mesomorphic Properties of n-Alkyl-4'-n-Pentanoyloxy-Biphenyl-4-Carboxylates
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Esters in the homologous series n-alkyl-4'-n-pentanoyloxy-biphenyl-4-carboxylates (n4COOBC, n=1-12) have been synthesized.Mesomorphic properties and phase transitions have been determined using polarizing hot-stage microscopy, DSC and x-ray.Phase transitions from SA-SB crystal and hexatic (tentatively) have been observed.The relationship between the incidence of hexatic phase and molecular structure has been discussed.
- Surendranath, V.,Fishel, D. L.,Vries, A de,Mahmood, R.,Johnson, D. L.
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