- A dual probe for selective sensing of Zn (II) by fluorescent and Cu (II) by colorimetric methods in different systems based on 7,8-benzochromone-3-carbaldehyde -(fluorescein)hydrazone
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In this study, a novel fluorescent probe sensor, 7,8-benzochromone-3-carbaldehyde (fluorescein)hydrazone L, was designed and synthesized. Based on the photoinduced electron transfer (PET) process, L can detect Zn2+ in the solution of EtOH/H2O (9/1, V/V). The probe had high selectivity and sensitivity to Zn2+ with a lower detection limit of 3.4 × 10?7 M. Furthermore, the coordination ratio of L-Zn2+ was 1:1, which could be corroborated by Job's plot. In addition, in the EtOH/ H2O (5/2, V/V) solution of the probe L, Cu2+ was added to produce a marked change in color from achromatous to yellow, indicating that the probe L could detect Cu2+ by colorimetry, which was detectable by the naked eye, simply and quickly. According to the Benesi-Hildebrand equation, the complexing constants values of L-Zn2+ and L-Cu2+ were 9.8 × 104 M-1 and 1.009 × 105 M-1, respectively.
- Li, Si-liang,Li, Tian-rong,Liu, Cong,Liu, Kui,Sun, Jie,Tian, Li-mei,Xue, Jia,Yang, Zheng-yin
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Read Online
- Negative correlations between cultivable and active-yet-uncultivable pyrene degraders explain the postponed bioaugmentation
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Bioaugmentation is an effective approach to remediate soils contaminated by polycyclic aromatic hydrocarbons (PAHs), but suffers from unsatisfactory performance in engineering practices, which is hypothetically explained by the complicated interactions between indigenous microbes and introduced degraders. This study isolated a cultivable pyrene degrader (Sphingomonas sp. YT1005) and an active pyrene degrading consortium (Gp16, Streptomyces, Pseudonocardia, Panacagrimonas, Methylotenera and Nitrospira) by magnetic-nanoparticle mediated isolation (MMI) from soils. Pyrene biodegradation was postponed in bioaugmentation with Sphingomonas sp. YT1005, whilst increased by 30.17% by the active pyrene degrading consortium. Pyrene dioxygenase encoding genes (nidA, nidA3 and PAH-RHDα-GP) were enriched in MMI isolates and positively correlated with pyrene degradation efficiency. Pyrene degradation by Sphingomonas sp. YT1005 only followed the phthalate pathway, whereas both phthalate and salicylate pathways were observed in the active pyrene degrading consortium. The results indicated that the uncultivable pyrene degraders were suitable for bioaugmentation, rather than cultivable Sphingomonas sp. YT1005. The negative correlations between Sphingomonas sp. YT1005 and the active-yet-uncultivable pyrene degraders were the underlying mechanisms of bioaugmentation postpone in engineering practices.
- Jiang, Bo,Chen, Yating,Xing, Yi,Lian, Luning,Shen, Yaoxin,Zhang, Baogang,Zhang, Han,Sun, Guangdong,Li, Junyi,Wang, Xinzi,Zhang, Dayi
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- General method for the synthesis of salicylic acids from phenols through palladium-catalyzed silanol-directed C-H carboxylation
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A silanol-directed, palladium-catalyzed C-H carboxylation reaction of phenols to give salicylic acids has been developed. This method features high efficiency and selectivity, and excellent functional-group tolerance. The generality of this method was demonstrated by the carboxylation of estrone and by the synthesis of an unsymmetrically o,o′-disubstituted phenolic compound through two sequential C-H functionalization processes.
- Wang, Yang,Gevorgyan, Vladimir
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p. 2255 - 2259
(2015/02/19)
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- Regioselective ortho-carboxylation of phenols catalyzed by benzoic acid decarboxylases: A biocatalytic equivalent to the Kolbe-Schmitt reaction
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The enzyme catalyzed carboxylation of electron-rich phenol derivatives employing recombinant benzoic acid decarboxylases at the expense of bicarbonate as CO2 source is reported. In contrast to the classic Kolbe-Schmitt reaction, the biocatalytic equivalent proceeded in a highly regioselective fashion exclusively at the ortho-position of the phenolic directing group in up to 80% conversion. Several enzymes were identified, which displayed a remarkably broad substrate scope encompassing alkyl, alkoxy, halo and amino- functionalities. Based on the crystal structure and molecular docking simulations, a mechanistic proposal for 2,6-dihydroxybenzoic acid decarboxylase is presented.
- Wuensch, Christiane,Gross, Johannes,Steinkellner, Georg,Lyskowski, Andrzej,Gruber, Karl,Glueck, Silvia M.,Faber, Kurt
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p. 9673 - 9679
(2014/03/21)
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- Regioselective enzymatic carboxylation of phenols and hydroxystyrene derivatives
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The enzymatic carboxylation of phenol and styrene derivatives using (de)carboxylases in carbonate buffer proceeded in a highly regioselective fashion: Benzoic acid (de)carboxylases selectively formed o-hydroxybenzoic acid derivatives, phenolic acid (de)carboxylases selectively acted at the β-carbon atom of styrenes forming (E)-cinnamic acids.
- Wuensch, Christiane,Glueck, Silvia M.,Gross, Johannes,Koszelewski, Dominik,Schober, Markus,Faber, Kurt
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supporting information; experimental part
p. 1974 - 1977
(2012/06/15)
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- Importance of equilibrium fluctuations between most stable conformers in the control of the reaction mechanism
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Hydrolysis of closely related compounds show how subtle structural differences markedly change reaction mechanisms. While in the hydrolysis of 3-acetoxy-2-naphthoic acid (3AC2NA) the reacting groups rotate freely, favoring intramolecular general base catalysis, the 1-acetoxy-2-naphthoic acid (1AC2NA) isomer is caged in an energy wall that freezes a conformation suitable for intramolecular nucleophilic attack, in contrast to the results expected for reactions governed largely by electronic effects. The results highlight the importance of the dynamics of equilibrium fluctuations between most stable conformers in the control of the reaction mechanism, (i) promoting the nucleophilic attack in 1AC2NA by allowing the most stable conformers to equilibrate only via rotation in a direction that intercepts the reaction coordinate and (ii) favoring a general base-catalyzed water attack in 3AC2NA by favoring equilibration via rotation that allows inclusion of a water molecule in a proper position for reaction.
- Souza, Bruno S.,Nome, Faruk
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supporting information; experimental part
p. 7186 - 7193
(2011/01/12)
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- Carboxylation of naphthols with sodium ethyl carbonate
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The carboxylation of α- and β-naphthols with sodium ethyl carbonate was studied. Conditions for the regioselective carboxylation of α-naphthol in the 2- and 4-positions and β-naphthol in the 3-position were found. Simple and convenient methods for the preparation of 1-hydroxy-2-naphthoic, 1-hydroxy-4-naphthoic, and 2-hydroxy-3-naphthoic acids were developed. Copyright
- Suerbaev, Kh. A.,Mikhnenko,Akhmetova,Shalmagambetov,Chepaikin
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p. 335 - 337
(2007/10/03)
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- Microwave-accelerated crossed cannizzaro reaction using barium hydroxide under solvent-free conditions
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A solventless and expeditious method for the preparation of alcohols is described from aldehydes using barium hydroxide, Ba(OH)2.8H2O, and paraformaldehyde. A comparison of this microwave-accelerated Cannizzaro reaction to the one under conventional heating mode is also reported.
- Varma, Rajender S.,Naicker, Kannan P.,Liesen, Per J.
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p. 8437 - 8440
(2007/10/03)
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- A process for preparation of an aromatic carboxylic acid
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The invention relates to a process for the preparation of an aromatic carboxylic acid or a derivative thereof, characterised by dissolving a derivative of a hydroxylated aromatic compound in an organic solvent, especially ethylenegylcol monoethyl ether, 3-methoxy-1-butanol or 1-methoxy-2-propanol, or mixtures thereof, in the presence pf CO2 or a source of CO2 in an autoclave and optionally neutralising the derivative of the carboxylic acid. The derivatives are preferably alkaline salts.
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- Process for producing azo pigment
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A process for producing an azo pigment, which comprises coupling an aromatic diazonium compound with 3-hydroxy-2-naphthoic acid and at least one binaphthol and optionally, laking the resulting pigment.
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- Metal Template ortho-Acylation of Phenols. Direct Synthesis of Salicylic Acid Chlorides and Derivatives
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A direct synthesis of salicylic acid chlorides is achieved via "metal-driven" intracomplex acylation of bromomagnesium and aluminum phenoxides with phosgene.Salicylic acids 5 and some derivatives 6, 7 can be obtained by quenching the reaction mixture with convenient reagents.Moreover the reaction of lithium phenylacetylide with 3 provides a new convenient approach to ortho-hydroxyaryl alkynyl ketones like 8.The oriented complex 2, involving the metal phenoxide and phosgene is proposed to account for the ortho-regioselective control of the reaction.
- Sartori, Giovanni,Casnati, Giuseppe,Bigi, Franca,Bonini, Giovanni
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p. 763 - 766
(2007/10/02)
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- Synthesis of Menadione
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New methods conceptually different from previous approaches are described for the preparation of 2-methyl-1,4-naphthoquinone (menadione), an antihemorrhagic agent.Recently the bisulphite adduct of menadione has been shown to be a promising plant growth regulator.
- Rao, A. V. Rama,Deshpande, V. H.,Ravichandran, K.
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p. 233 - 235
(2007/10/02)
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- HETEROCYCLIC STEROIDS-3
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%Synthesis of 11-oxa and 11- oxa- 15,16- diaza analogs of equilenin. 22 refs.
- KASTURI TR,ARUNACHALAM T
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p. 203 - 209
(2007/10/05)
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