- Effect of Cation Capture by Crown Ether and Polar Solvent in the Carboxylation with CO2 of Alkali Metal 2-Naphtholates under Ordinary Conditions
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An efficient method for the carboxylation of sodium 2-naphtholate and potassium 2-naphtholate in benzene with 10 mol% of crown ether or aprotic polar solvents under 1 atm of carbon dioxide at 60 °C affords 2-hydroxynaphthalene-1-carboxylic acid in yields ranging from 14.6 to 43.8% and 26.7 to 66.0%, respectively.
- Baxter, Joseph,Yamaguchi, Tatsuaki
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- Carboxylations of alkali metal phenoxides with carbon dioxide
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The reaction mechanism of the Kolbe-Schmitt reaction of phenol and 2-naphthol has been investigated. An alkali metal phenoxide-CO2 complex is not an intermediate that can be easily transformed into a carboxylic acid, such as salicylic acid (SA) and p-hydroxybenzoic acid (pHBA). A direct carboxylation of phenoxide with CO2 takes place even at room temperature, and is competitive with the formation of the CO2 complex. The resulting complex decomposes thermally (above ca. 100°C) to phenoxide, which then undergoes further competitive reactions. Experiments using a carbon-13 labeled complex support a mechanism of direct carboxylation, and not the mechanism via a CO2 complex. The reactivity, C-13 NMR and MOPAC/PM3 calculations suggest a new carbonate-like structure for the CO2 complex.
- Kosugi, Yoshio,Imaoka, Yoshio,Gotoh, Fumisato,Rahim,Matsui, Yoshihisa,Sakanishi, Kinya
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- Development of an azo-naphthol-based probe for detecting hypochlorite (ClO?) via color change in aqueous solution
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A novel azo-naphthol-based colorimetric probe APBN (sodium 4-((E)-(4-(((E)-(2-hydroxynaphthalen-1-yl)methylene)amino)phenyl)diazenyl)benzenesulfonate) was synthesized and applied for detecting hypochlorite (ClO?) in aqueous solution. It showed a good selectivity toward ClO? by color change from yellow to colorless via the cleavage of C[dbnd]N bond. Detection limit for ClO? was determined as 0.47 μM. APBN can be used to determine ClO? in real water sample, and also successfully detect ClO? using test kit coated with APBN. The sensing mechanism of APBN to ClO? was illustrated by theoretical calculation.
- Kim, Cheal,Lee, Hangyul,Rha, Chang Joo
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- Enantioselective Copper-Catalyzed Electrophilic Dearomative Azidation of β-Naphthols
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The first example of copper-catalyzed enantioselective dearomative azidation of β-naphthols using a readily available N3-transfer reagent is reported. A series of 2-hydroxy-1-naphthamides bearing a complex N-substituent were converted to the corresponding products in high yields with up to 96% ee, and chiral 1-azido-2-hydroxy-1-naphthoates were obtained with up to 90% ee under mild reaction conditions. The azides could be further transformed into the corresponding 1,2,3-triazoles smoothly via "click" reaction.
- Wang, Chong-Ji,Sun, Jian,Zhou, Wei,Xue, Jing,Ren, Bing-Tao,Zhang, Guang-Yi,Mei, Yan-Le,Deng, Qing-Hai
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- Catalyst-free aerobic oxidation of aldehydes into acids in water under mild conditions
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The first example of catalyst-free aerobic oxidation of aldehydes in water under respective acidic, neutral and alkaline conditions was developed. The sole oxidant is molecular oxygen of 1 atmosphere and reactions can proceed under extremely mild conditions. This procedure covers a wide range of aldehydes, and operates easily. No additives and catalysts were required for this purpose, and most of the aldehydes can be converted to their corresponding carboxylic acids with good to excellent yields, in addition, no side-product formation could be observed during or after the reactions. To well illustrate why the oxidation rate becomes fast firstly and then slows with increased temperatures, five control reactions were carried out and a Fe3+/Fe2+ recycling system was introduced to facilitate the aldehyde oxidation rate. The generality of this method offers the potential for industrial aldehyde-containing waste water treatment.
- Zhang, Yue,Cheng, Yujia,Cai, Huizhuo,He, Shaopo,Shan, Qiheng,Zhao, Hongwei,Chen, Yiping,Wang, Bo
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supporting information
p. 5708 - 5713
(2017/12/06)
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- Ni-catalyzed reduction of inert C-O bonds: A new strategy for using aryl ethers as easily removable directing groups
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An efficient Ni-catalyzed protocol for the reductive cleavage of inert C-O bonds has been developed. The method is characterized by its simplicity and wide scope, thereby allowing the use of aryl ethers as easily removable directing groups in organic synthesis.
- Alvarez-Bercedo, Paula,Martin, Ruben
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supporting information; scheme or table
p. 17352 - 17353
(2011/02/23)
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- Oxidation of 2-hydroxynaphthaldehyde by alkaline N-bromosuccinimide - A kinetic and mechanistic study
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The kinetics of the oxidation of 2-hydroxynaphthaldehyde (2-HNA) by N-bromosuccinimide (NBS) in aqueous alkaline medium at a constant ionic strength of 0.60 mol dm-3 was studied titrimetrically. The reaction is of first order in [NBS] and of fractional order in both [2-HNA] and [alkali]. Addition of products has no significant effect on the reaction rate. However, increasing ionic strength and decreasing dielectric constant of the medium increases the rate. The oxidation process in alkaline medium has been shown to proceed via the formation of a complex between the active species of the oxidant and the substrate followed by the decomposition of the complex in a slow rate determining step to yield the product. Some reaction constants involved in the mechanism were determined. The calculated and observed rate constants agree excellently. The activation parameters were computed with respect to the slow step of the mechanism.
- Naik, Govindrajnaj T.,Angadi, Mahantesh A.,Harihar, Abdulazizkhan L.
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experimental part
p. 255 - 260
(2010/04/05)
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- Kinetics and mechanism of oxidation of 2-hydroxynaphthaldehyde by alkaline periodate
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The oxidation of 2-hydroxynaphthaldehyde (2-HNA) by alkaline species of periodate, H2IO63- has a 1: 1 stoichiometry and exhibits unit order in [IO4-] and less than unit order each in [2-HNA] and [OH-]. The reaction proceeds via the formation of an oxidant-substrate complex and its subsequent decomposition in a rate determining step to yield products. The effects of ionic strength, dielectric constant and initially added products have been studied. The reaction constants involved in the mechanism have been computed. There is a good agreement between the observed and calculated rate constants under different experimental conditions of the reaction. The activation parameters have been calculated with respect to the slow step of the proposed mechanism of reaction.
- Kathari,Harihar,Nandibewoor
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p. 111 - 114
(2007/10/03)
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- Effects of alkali and alkaline earth metals on the Kolbe-Schmitt reaction
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It was found that the carboxylations of magnesium, calcium, and barium phenoxides with carbon dioxide at 260 °C produced salicylic acid and dicarboxylic acids (4-hydroxyisophthalic acid and 2-hydroxyisophthalic acid) in very high yields (80-100%), exceeding that of the ordinary Kolbe-Schmitt reaction. The orientation (ortho/para ratio) was controlled not only by chelations of the intermediate with alkaline earth metal (Mg, Ca, Ba) ions, resulting in salicylic acid, but also by the sizes of metal ions (Rb, Cs), giving p-hydroxybenzoic acid in a much higher ratio than the widely used method with potassium or sodium phenoxide. These alkaline earth metals worked to produce 3-hydroxy-2-naphthoic acid by the reaction of 2-naphthoxide with carbon dioxide, but the yield of 6-hydroxy-2-naphthoic acid was comparable to that of 3-hydroxy-2-naphthoic acid when cesium or rubidium 2 naphthoxide was employed. Considerably high yields (～60%) of 6-hydroxy-2-naphthoic acid, a monomer of one of the best liquid-crystal polymers, was attained by the carboxylation of cesium or rubidium 2-naphthoxide in the presence of potassium or sodium carbonate, where the alkali metal ion was supposed to increase the reactivity of the substrate. The formation of "binol" was observed in the preparation of 2-naphthoxides with metal hydroxides, especially with copper(II) ion.
- Rahim, Mohammad Abdur,Matsui, Yoshihisa,Kosugi, Yoshio
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p. 619 - 622
(2007/10/03)
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- Crystalline cepham acid addition salts and processes for their preparation
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Novel crystalline cephem acid addition salts and processes for their preparation Compounds of the formula I STR1 in which n is equal to 1 or 2 and m is 0.4-2.6, and where X is the anion of a carboxylic acid, have antibacterial activity.
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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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- COMPOSITIONS AND METHODS FOR THE TREATMENT OF IMMUNOMEDIATED INFLAMMATORY DISORDERS
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Compositions and methods for the prevention and treatment of immunomediated inflammatory disorders, especially for those disorders associated with the respiratory tract, are provided. More particularly, a tryptase inhibitor, typically a hydroxyaroyl or hydroxyheteroaroyl substituted dipeptide, is administered. Also provided by this invention are pharmaceutical compositions, typically aerosol or topical, as well as aerosol devices for administering these compositions intranasally.
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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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