- Synthesis of 4-[(1R,4R)-3-oxo-p-menthan-2-ylidenemethyl]benzoic acid and its esters
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Carbonylation of (E)-2-(4-halobenzylidene)-p-menthan-3-ones, catalyzed by PdCl2(PPh3)2, gave a distereometric mixure of 4-[(1R,4R)- and (1R,4S)-3-oxo-p-menthan-2-ylidenemethyl]benzoic acids, whose reaction with phenols gave 1R,4R diastereomers of the corresponding esters. 2005 Pleiades Publishing, Inc.
- Drushlyak,Kutulya,Pivnenko,Vashchenko
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- Synthetic method 4 - alkoxyphenol compounds
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The invention discloses a synthetic method of 4 - alkoxyphenol compounds, and belongs to the field of organic chemical synthesis. The method is as follows: An aryl alkyl ether compound is added to the sealing tube. The catalyst dimerization acetic acid rhodium and the oxidizing agent iodobenzene diethyl ester are added, a solvent trifluoroacetic anhydride is added, and the 4 -alkoxyphenol compound is prepared by heating reaction. To the invention, high regioselectivity direct hydroxylation of the aryl alkyl ether compound is realized, the application range of the substrate is wide, the yield is high, the activity after amplification reaction does not significantly decay, and higher yield is still obtained. The utility model has good practicability and industrial application prospect.
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Paragraph 0041-0043-0044
(2021/09/29)
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- Para -Selective hydroxylation of alkyl aryl ethers
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para-Selective hydroxylation of alkyl aryl ethers is established, which proceeds with a ruthenium(ii) catalyst, hypervalent iodine(iii) and trifluoroacetic anhydride via a radical mechanism. This protocol tolerates a wide scope of substrates and provides a facile and efficient method for preparing clinical drugs monobenzone and pramocaine on a gram scale.
- Zhu, Runqing,Sun, Qianqian,Li, Jing,Li, Luohao,Gao, Qinghe,Wang, Yakun,Fang, Lizhen
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supporting information
p. 13190 - 13193
(2021/12/16)
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- Dendritic Oligoglycerol Regioisomer Mixtures and Their Utility for Membrane Protein Research
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Dendrons are an important class of macromolecules that can be used for a broad range of applications. Recent studies have indicated that mixtures of oligoglycerol detergent (OGD) regioisomers are superior to individual regioisomers for protein extraction. The origin of this phenomenon remains puzzling. Here we discuss the synthesis and characterization of dendritic oligoglycerol regioisomer mixtures and their implementation into detergents. We provide experimental benchmarks to support quality control after synthesis and investigate the unusual utility of OGD regioisomer mixtures for extracting large protein quantities from biological membranes. We anticipate that our findings will enable the development of mixed detergent platforms in the future.
- Urner, Leonhard H.,Goltsche, Katharina,Selent, Marleen,Liko, Idlir,Schweder, Marc-Philip,Robinson, Carol V.,Pagel, Kevin,Haag, Rainer
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supporting information
p. 2537 - 2542
(2020/12/30)
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- Tetracyano-anthraquinone dimethane micromolecular receptor material as well as preparation method and application thereof
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The invention relates to a tetracyano-anthraquinone dimethane micromolecular acceptor material as well as a preparation method and application thereof. The structure of the acceptor material is as shown in a formula I, which is described in the specification. The micromolecular acceptor material has good solubility and stability, the absorption spectrum is well matched with the solar spectrum, andthe micromolecular acceptor material can be used for organic solar cells.
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Paragraph 0059-0062; 0078-0081
(2020/05/11)
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- Scalable and Phosphine-Free Conversion of Alcohols to Carbon-Heteroatom Bonds through the Blue Light-Promoted Iodination Reaction
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One of the fundamental and highly valuable transformations in organic chemistry is the nucleophilic substitution of alcohols. Traditionally, these reactions require strategies that employ stoichiometric hazardous reagents and are associated with difficulty in purification of the by-products. To overcome these challenges, here, we report a simple route toward the diverse conversion of alcohols via an SN2 pathway, in which blue light-promoted iodination is used to form alkyl iodide intermediates from simple unreactive alcohols. The scope of the process tolerates a range of nucleophiles to construct C-N, C-O, C-S, and C-C bonds. Furthermore, we also demonstrate that this method can be used for the preparation and late-stage functionalization of pharmaceuticals, as highlighted by the syntheses of thiocarlide, butoxycaine, and pramoxine.
- Liu, Bin,Elder, W. Zachary,Miyake, Garret M.
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supporting information
p. 3717 - 3727
(2020/03/04)
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- Oxalic Diamides and tert-Butoxide: Two Types of Ligands Enabling Practical Access to Alkyl Aryl Ethers via Cu-Catalyzed Coupling Reaction
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A robust and practical protocol for preparing alkyl aryl ethers has been developed, which relies on using two types of ligands to promote Cu-catalyzed alkoxylation of (hetero)aryl halides. The reaction scope is very general for a variety of coupling partners, particularly for challenging secondary alcohols and (hetero)aryl chlorides. In case of coupling with aryl chlorides and bromides, two oxalic diamides serve as the powerful ligands. The tert-butoxide is first demonstrated as a ligand for Cu-catalyzed coupling reaction, leading to alkoxylation of aryl iodides complete at room temperature. Additionally, a number of carbohydrate derivatives are applicable for this coupling reaction, affording the corresponding carbohydrate-aryl ethers in 29-98% yields.
- Chen, Zhixiang,Jiang, Yongwen,Zhang, Li,Guo, Yinlong,Ma, Dawei
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supporting information
p. 3541 - 3549
(2019/02/26)
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- Efficient dealkylation of aryl alkyl ethers catalyzed by Cu2O
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An efficient protocol for dealkylation of aryl alkyl ethers under the catalysis of inexpensive and easily reusable Cu2O has been described. The phenol products were obtained in high yields, and a range of functional groups were well tolerated. The choice of solvent is critical to the catalysis, and CH3OH proved to be the optimal choice. Mechanistic investigations showed that this reaction possibly proceeds via a single-electron transfer (SET) process.
- Liu, Lingxian,Li, Zengguang,Chen, Changjun,Li, Huanrong,Xu, Lijin,Yu, Zhiyong
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supporting information
p. 2447 - 2453
(2018/04/11)
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- Dimethylglyoxime as an efficient ligand for copper-catalyzed hydroxylation of aryl halides
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The CuI/dimethylglyoxime (CuI/DMG) catalyzed direct hydroxylation of aryl iodides with CsOH takes place at 120°C in a mixed solvent system (DMSO–H 2O ,1:1), afforded the corresponding phenols in good to excellent yield. Aryl bromides are found to be less reactive than aryl iodides under these reaction conditions. Graphical Abstract: SYNOPSIS. (CuI/DMG) catalyzed synthesis of phenol from aryl iodide and aryl bromide in presence of mixed solvents (H 2O : DMSO) is reported in this paper. This protocol is general, economical, easy and convenient for transformation of aryl iodides and bromides to substituted phenols under mild reaction conditions. [Figure not available: see fulltext.].
- Shendage, Suresh S
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- Synthesis and Properties of Triphenodioxazine-Based Conjugated Polymers for Polymer Solar Cells
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As a fused-ring conjugated unit, triphenodioxazine, has been applied in two series of thiophene-free conjugated polymers for polymer solar cells. The polymers were synthesized through a multi-step synthetic route, and the substituents had a great effect on the reactivity of the reactants. Relationships among the polymer structures as well as thermal, optical, and electrochemical properties were investigated in detail by experimental data analysis and theoretical simulation. The polymers possess highly planar backbones, broad Vis/NIR absorption bands, suitable frontier molecular orbital energies, and low band gaps ranging from 1.3 to 1.8 eV. The power conversion efficiencies of their photovoltaic devices are about 1 %. Introducing longer alkyl side chains into a polymer can bring about a better film-forming ability and improve the photovoltaic performance.
- Gong, Xiaohui,Han, Pei,Wen, Hui,Sun, Ying,Zhang, Xueqin,Yang, Hong,Lin, Baoping
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p. 3689 - 3698
(2017/07/22)
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- Silica chloride: An efficient promoter for oxidation of arylboronic acids to phenols
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This work reports simple, highly efficient protocol for the oxidation of arylboronic acids. Various arylboronic acids were selectively and completely converted into their corresponding oxidized phenols using H2O2 as an oxidant in presence of catalytic amount of silica chloride. The results show that silica chloride is a suitable and efficient promoter for the oxidation of arylboronic acids. Heterogeneous catalyst, mild reaction conditions, easy availability of the reagent, easy work-up, excellent yield of corresponding phenols, short reaction time and broad substrate scope makes this protocol attractive and a practical alternative to the existing methods.
- Wagh, Ravindra B.,Nagarkar, Jayashree M.
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supporting information
p. 3323 - 3326
(2017/07/27)
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- Method for synthesizing 4-butoxyphenol
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The invention provides a method for synthesizing 4-butoxyphenol. The method comprises the steps of firstly, protecting one of two hydroxyl groups of hydroquinone with an acetyl group, enabling the hydroquinone to be converted into a mono-hydroxyl protected product in an almost-isometric manner by using an ester exchange reaction, then, subjecting the mono-hydroxyl protected product to a reaction with halogenated butane so as to etherifying the unprotected hydroxyl group, and then, carrying out hydrolysis to remove acetyl protection, thereby obtaining high-yield 4-butoxyphenol. According to the method, the control is simple, the yield is stable, and the purity of the synthesized product reaches 98% or more through simple crystallization in an aqueous solution.
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Paragraph 0016
(2017/07/19)
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- Intramolecular charge transfer interactions and molecular order of rod like mesogens
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A mesogenic 4-((4-(alkoxy)phenoxy)carbonyl)phenyl-4-(dimethylamino)benzoate series with terminal chains varying from C2 to C12 carbons (even number carbons only) are synthesised and their mesophase transitions are examined by hot-stage optical polarising microscopy as well as differential scanning calorimetry. Accordingly, enantiotropic nematic mesophase for all the homologs and an additional smectic A phase for the C12 homolog is observed. Powder X-ray diffraction studies confirm the interdigitated bilayer organization in the smectic A phase for the C12 homolog. It is remarkable that the mesogens under investigation only differ in the linking unit i.e. ester versus imine in contrast to recently reported mesogens, yet show a large difference in certain properties. Accordingly, the crystal structure of the C4 homolog reveals a triclinic lattice with P1 space group in which the molecules are packed in a slipped co-facial configuration. Additionally, a detailed investigation of the C12 mesogen by UV-visible and fluorescence spectroscopy as well as computational methods unveils interesting features. The fluorescence spectrum of the C12 mesogen is observed at 366 nm with a shoulder at 433 nm and a large solvent polarity induced red-shift is noticed in contrast to a structurally similar homolog examined recently. Further, the C12 mesogen in solvents such as ethyl acetate, dichloromethane, chloroform, tetrahydrofuran, acetonitrile and dimethyl sulfoxide exhibited dual emission. Therefore, density functional theory and time dependent density functional theory calculations are utilized to obtain insight. Besides variation in the dihedral angle between rings B and C for the C12 mesogen, it is found that the highest occupied molecular orbital (HOMO) is localized on the N,N-dimethylaminobenzene moiety while the lowest unoccupied molecular orbital (LUMO) is mostly concentrated on the phenyl benzoate unit. Time dependent-density functional theory (TD-DFT) calculations disclose the orbitals involved in the dominant excited state electronic transitions and their corresponding energies together with oscillator strength. The high resolution 1D and 2D separated local field (SLF) solid state 13C NMR investigation of the C12 mesogen lead to the orientational order parameters of the phenyl rings of the core in the SmAd phase. The temperature versus alignment induced chemical shifts reveals an increase in chemical shifts with a decrease in temperature in the smectic Ad phase in concurrence with order parameter values. Thus, understanding the photophysical properties of mesogens with dimethylamino moieties would facilitate better design of molecules for application in organic light emitting diodes for polarized emission.
- Reddy, M. Guruprasad,Lobo, Nitin P.,Varathan,Easwaramoorthi,Narasimhaswamy
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p. 105066 - 105078
(2015/12/30)
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- Facile conversion of para-benzoquinones to para-alkoxyphenols with primary/secondary alcohols and amberlyst-15: A process showing novel reducing property of such alcohols
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A new efficient methodology has been developed for the synthesis of para-alkoxyphenols, an important group of anti-melanoma compounds, by heating alcoholic solutions of para-benzoquinones in the presence of amberlyst-15. The most notable feature here is the behaviour of the used primary or secondary alcohol as an effective reducing agent.
- Mondal, Rina,Guha, Chayan,Mallik, Asok K.
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supporting information
p. 86 - 89
(2014/01/06)
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- Synthesis and liquid crystal property of new fluoro coumarin carboxylates
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New liquid crystalline 4-alkoxyphenyl-coumarin-3-carboxylates 6a-e, 7a-g, 8a-e, and 9a-e were prepared by reacting various coumarin-3-carboxylic acids 5a-d with 4-(alkoxy) phenols 4a-g in the presence of 1(3-dimethylaminopropyl-3- ethylcarbodiimide/dimethyl amino pyridine (EDCI/DMAP) as a coupling agent. The structures of the new coumarin derivatives were confirmed by spectral analysis and the liquid crystalline property was established by polarizing optical microscope and by differential scanning calorimetric techniques. The diethyl amine and morpholine were taken as electron-donating and -CF3 as electron-withdrawing groups at the seventh position of the coumarin-3-carboxylic acids to check the mesomorphic property in all new 4-alkoxyphenyl-coumarin-3- carboxylates. Among them, only 4-alkoxyphenyl-7-triflouromethyl-coumarin-3- carboxylates 7a-g exhibited liquid crystalline SmA phase.
- Mahadevan, Kittappa M.,Harishkumar, Hosanagara N.,Masagalli, Jagadeesh N.,Srinivasa, Hosapalya T.
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- Side-chain liquid-crystalline polymers based on flexible rod-like mesogen directly attached to backbone
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In this article, we report the synthesis and characterization of a new end-on side-chain liquid crystalline polymer (SCLCP), poly[4-(4′- alkoxyphenyloxymethylene)styrene] [denoted as Poly(n-POMS), where n is the carbon number of the alkyl tail, n = 2, 4, 6, 8, 12, 16], with the flexible rod-like mesogenic side-chain directly attached to the polymer backbone without flexible spacer. The polymer was obtained by using free radical polymerization. The chemical structures of Poly(n-POMS) and the corresponding monomer were characterized using various techniques with satisfactory analysis data. A combination analysis of differential scanning calorimetry, polarized light microscopy, small angle X-ray scattering, and wide-angle X-ray diffraction has been conducted to investigate the phase behavior of Poly(n-POMS). Poly(2-POMS), Poly(4-POMS), and Poly(6-POMS) are amorphous. Poly(8-POMS) develops partially into the liquid crystal phase, and Poly(12-POMS) and Poly(16-POMS) self-assembly into the smectic A (SmA) phase. Upon increasing temperature, the phase transition of Poly(16-POMS) follows the sequence of SmA1 ? SmA2 ? isotropic (I), which may be attributed to the conformation isomerization of the flexible rod-like mesogens.
- Zheng, Jun-Feng,Yu, Zhen-Qiang,Liu, Xin,Chen, Xiao-Fang,Yang, Shuang,Chen, Er-Qiang
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p. 5023 - 5031
(2013/01/15)
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- O-Alkylation of phenol derivatives via a nucleophilic substitution
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The alkylation of phenol derivatives can be achieved in good yield via Lewis or Bronsted acid. The only by-product of the reaction is water and the catalyst can be recycled when using Bronsted acid.
- Cazorla, Clement,Pfordt, Emilie,Duclos, Marie-Christine,Metay, Estelle,Lemaire, Marc
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scheme or table
p. 2482 - 2488
(2011/10/31)
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- METHODS AND COMPOSITIONS FOR CONTROL OF GYPSY MOTHS, Lymanria dispar
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The invention provides in part dialkoxybenzene and eugenol compounds for controlling infestation by a Lymantria dispar, and methods thereof. The compounds include a compound of Formula I: where R1 may be methyl, ethyl, propyl, n-butyl, isopentyl (3-methylbutyl) or allyl; R2 may be at positions 2, 3 or 4 and may be H, methyl, ethyl, propyl, n-butyl, isopentyl (3-methylbutyl) or allyl; and R3 may be optionally present at positions 2, 3 and 4, and is allyl; with the provisos that when R2 is at position 2, R3 if present is at position 3, or when R2 is at to position 3, R3 if present is at positions 2 or 4, or when R2 is at position 4, R3 if present is at position 2; or of Formula II: where R1 may be methyl, ethyl, propyl, n-butyl, isopentyl (3-methylbutyl) or allyl; or mixtures thereof.
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Page/Page column 11
(2010/08/07)
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- METHODS AND COMPOSITIONS FOR CONTROL OF CABBAGE LOOPER, Trichoplusia ni
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The invention provides in part dialkoxybenzene compounds for controlling infestation by a Trichoplusia ni, and methods thereof. The compounds include a compound of Formula I: where R1 may be methyl, ethyl, propyl, n-butyl, isopentyl(3-methylbutyl) or allyl; R2 may be at positions 2, 3 or 4 and may be H, methyl, ethyl, propyl, n-butyl, isopentyl(3-methylbutyl) or allyl; and R3 may be optionally present at positions 2, 3 and 4, and is allyl; except that when R2 is at position 2, R3 if present is at position 3, and when R2 is at position 3, R3 if present is at positions 2 or 4, and when R2 is at position 4, R3 if present is at position 2, and when R2 is at position 4 and R3, if present, has reacted with an OH group at position 1 in a Markovnikov sense, then R3 becomes R4, a dihydrofuran.
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Page/Page column 10
(2010/07/04)
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- Dialkoxybenzene and dialkoxyallylbenzene feeding and oviposition deterrents against the cabbage looper, trichoplusia ni: Potential insect behavior control agents
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The antifeedant, oviposition deterrent, and toxic effects of individual dialkoxybenzene compounds/sets and of hydroxy- or alkoxy-substituted allylbenzenes, obtained through Claisen rearrangement of substituted allyloxybenzenes, were assessed against the cabbage looper, Trichoplusia ni, in laboratory bioassays. Most of the compounds/sets strongly deterred larval feeding, with some exhibiting mild toxic and oviposition deterrent effects as well. Some of the compounds/sets were more active than the commercial insect repellent, DEET (N,N-diethyl-m-toluamide), as both feeding and oviposition deterrents against the cabbage looper. On the basis of the obtained oviposition data a general hypothesis was proposed regarding the oviposition sites: one binding mode with the alkyl and allyl groups on the same side of the benzene ring resulted in deterrence, the other with alkyl and allyl groups on opposite sides of the benzene ring resulted in stimulation. The results suggest some structure-activity relationships useful in improving the efficacy of the compounds and designing new, nontoxic insect control agents for agriculture.
- Akhtar, Yasmin,Yu, Yang,Isman, Murray B.,Plettner, Erika
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scheme or table
p. 4983 - 4991
(2011/08/06)
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- Zinc-catalyzed Williamson ether synthesis in the absence of base
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A zinc-catalyzed Williamson ether synthesis is described with microwave heating in the presence of DMF or stirring in an oil-bath using THF as solvent and in the absence of base. Zinc powder was found to be a highly efficient catalyst for the synthesis of aromatic ethers using microwave heating in the presence of N,N-dimethylformamide as well as under stirring in an oil-bath using tetrahydrofuran as solvent without any inorganic base. This method can be used for selective mono-, di- or tri-O-alkylations.
- Paul, Satya,Gupta, Monika
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p. 8825 - 8829
(2007/10/03)
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- SULFONAMIDE-SUBSTITUTED FUSED 7-MEMBERED RING COMPOUNDS, THEIR USE AS A MEDICAMENT, AND PHARMACEUTICAL PREPARATIONS COMPRISING THEM
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The present invention relates to compounds of formula I, in which X1, X2, X3, X4, Y1, Y2, Y3, Y4, R(3), R(4) and R(5) have the meanings mentioned in the specification, their preparation and their use, in particular in pharmaceuticals. The compounds effect the potassium channel or the I Ks channel opened by cyclic adenosine monophosphate (cAMP) and are outstandingly suitable as pharmaceutical active compounds, for example for the prophylaxis and therapy of cardiovascular disorders, in particular arrhythmias, for the treatment of ulcers of the gastrointestinal region or for the treatment of diarrheal disorders.
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- Etherification of phenols catalysed by solid-liquid phase transfer catalyst PEG400 without solvent
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Aromatic ethers were synthesised in excellent yields(above 86 %) and purity by the etherification of phenols with dimethyl sulfate or alkyl halides, catalysed by phase transfer catalyst PEG400 under solvent-free conditions, and the effects of some key reaction conditions were also studied.
- Cao, Yu-Qing,Pei, Ben-Gao
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p. 1759 - 1766
(2007/10/03)
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- Tilt Angle Variation as a Function of Chain Length and Temperature in the Smectic C Phases of p,Alkoxyphenyl-p,Alkoxybenzoates
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The variation of the tilt angle with temperature in the smectic C phase has generally been shown to be non-existent or very slow for compounds or mixtures with the nematic-smectic C transition, while in the case of systems with the smectic A-smectic C transition, a relation between the steepness of this variation, near the transition, and the width of the smectic A domain has been observed.In this work, the variation of tilt angle in the smectic C phase is described for p-alkoxyphenyl-p-alkoxybenzoate homologous series, for which the evolution of polymorphism can be controlled systematically, by varying stepwise the length of the aliphatic chains, and for which large domains can be obtained for each type of phase sequence, nematic-, smectic A- and isotropic-smectic C.After completing the discussion made previously on the incidence of chain length on polymorphism, we confirm that the variation of tilt angle with temperature is slowest for compounds with intermediate chain lengths corresponding to the largest smectic A temperature range; this variation becomes continuously steeper when the smectic A domain becomes narrow.In addition, we show that the same description can be extended to the other types of phase sequences, by using the hypothesis of a virtual smectic A-smectic C transition above the observed nematic- or isotropic-smectic C transition.In fact, short chain lengths for homologues with a nematic/smectic C transition, or long chain lengths for homologues with an isotropic/smectic C transition, lead to an increase of the tilt angle at the phase transition and to a decrease of the amplitude of its variation with temperature; in our description, this behaviour corresponds to an increase of the temperature range between the real and virtual transitions.As a consequence, the homologues with very short and very long chain lengths show a quasi temperature-independent tilt angle, while the other homologues present a tilt angle variation similar to that observed for compounds exhibiting a smectic C/smectic A transition.This feature indicates that there is no need to distinguish between different types of smectic C phase.
- Heinrich, B.,Guillon, D.
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- Synthesis of 4-alkoxyaryl β-D-glucopyranosides and their inhibitory effects on histamine release from rat peritoneal mast cells induced by concanavalin A
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The inhibitory effects of newly synthesized 4-alkoxyaryl β-D- glucopyranosides on histamine release from rat peritoneal mast cells induced by concanavalin A were examined. A plot of hydrophobicity (k') against inhibitory activity of the compounds showed a distinct maximum, and 4- decyloxy-2,3,6-trimethylphenyl β-D-glucopyranoside was the most potent inhibitor among the tested compounds.
- Wang,Furukawa,Nihro,Kakegawa,Matsumoto,Satoh
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p. 570 - 575
(2007/10/02)
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- Synthesis and anti lipid-peroxidation activity of hydroquinone monoalkyl ethers
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A series of hydroquinone monoalkyl ethers was synthesized and evaluated for anti lipid-peroxidation activity in rat liver microsomes. 4-Hexyloxy- 2,3,6-trimethylphenol (9), having a low redox potential, as well as ascorbic acid exhibited the strongest anti lipid-peroxidation activity (IC50 = 4.2 x 10-7 M). Structure-activity relationship studies demonstrated that the inhibitory effect of hydroquinone monoalkyl ethers on lipid peroxidation was increased by the acquisition of an optimum hydrophobicity and decreased by an insufficient or excessive hydrophobicity.
- Nihro,Furukawa,Sogawa,Wang,Miyataka,Matsumoto,Miki,Satoh
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p. 576 - 579
(2007/10/02)
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- O-MONOALKYLATION OF HYDROQUINONE BY ALCOHOLS
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The dependence of the initial rate of O-monoalkylation of hydroquinone by alcohols on the F constant of the alcohol radical has the following form: w0*104 = 21(F + 1.28)-5 + 0.44.The previously unknown steric constants F for hexyl, heptyl, cyclohexyl, and 2-ethoxyethyl radicals were determined by means of this relationship.
- Rybin, A. G.,Orlov, A. V.,Zil'berman, E. N.,Barskova, M. Z.
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p. 1609 - 1611
(2007/10/02)
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- Process for the preparation of mono-ethers of hydroquinones
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Mono-ethers of hydroquinones of formula (I) STR1 wherein R represents alkyl, alkoxy-alkyl, cycloalkyl, aryl-alkyl, or cycloalkyl-alkyl, and R1 is hydrogen or alkyl, cycloalkyl, aryl-alkyl, or cycloalkyl-alkyl, are prepared by contacting the corresponding hydroquinones with the corresponding alcohols ROH, in the presence of a catalytic mixture consisting of (a) a strong acid (b) a halogen or a hydrohalic acid selected from HBr, HI, I2, and Br2, and (c) H2 O2 in a molar amount lower than that of the starting hydroquinone.
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- Process for the preparation of mono-ethers of hydroquinones
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Mono-ethers of hydroquinones of formula (I) wherein, R represents alkyl, alkoxy-alkyl, cycloalkyl, aryl-alkyl, or cycloalkyl-alkyl, and, R1 is hydrogen or alkyl, cycloalkyl, aryl-alkyl, or cycloalkyl-alkyl,are prepared by contacting the corresponding hydroquinones with the corresponding alcohols ROH, in the presence of a catalytic mixture consisting of a) a strong acid b) a halogen or a hydrohalic acid selected from HBr, HI, I2, and Br2, and c) H2O2 in a molar amount lower than that of the starting hydroquinone.
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- ON THE 1,6-ADDITION OF ALKYLALUMINIUM COMPOUNDS TO para-QUINONES
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Ethyl, n-butyl and i-butylaluminium dichlorides undergo 1,6-addition to a conjugated bond system O=C-C=C-C=O of para-quinones.Methylaluminium dichloride is inactive in this addition, and triethylaluminium gives low yields.The reactivities of the quinones vary with their electron affinities, and the highest yields of 1,6-addition are obtained in the reactions of chlorine derivatives of 1,4-benzoquinone.The results are discussed in terms of a radical mechanism involving a homolytic cleavage of the Al-C bond in the donor-acceptor complex formed between the reactants followed by combination of alkyl radicals and aluminium derivatives of semiquinone within a cage.The stable donor-acceptor complexes and aluminium derivative of semiquinone were isolated and characterized from the reactions of aluminium trichloride with 2,3,5,6-tetramethyl-1,4-benzoquinone and 2,3,5,6-tetrachloro-1,4-benzoquinone, respectively.
- Florjanczyk, Zbigniew,Szymanska-Zachara, Ewa
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p. 127 - 138
(2007/10/02)
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- LIQUID CRYSTALLINE PROPERTIES OF 4-N-ALKOXYPHENYL 4-NITROBENZOATES.
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Twelve 4-alkoxyphenyl esters of 4-nitrobenzoic acid were synthesized. The mesophases were identified and the transition temperatures and enthalpies determined. The above series shows considerable similarity to the reverse analogues, i. e. , the 4-nitro-phenyl 4-n-alkoxybenzoates.
- Galewski,Sobczyk
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- Gas-Liquid Phase-transfer Synthesis of Phenyl Ethers and Sulphides with Carbonate as Base and Carbowax as Catalyst
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When a mixture of a phenol (or thiol) and an alkyl halide is passed, in the gaseous state, through a solid bed of potassium carbonate (or sodium hydrogencarbonate) and catalytic amounts of Carbowax 6000, contained in a glass column at 170 deg C, the corresponding ethers (or sulphides) may be collected at the outlet.The Carbowax acts in a similar manner to the crown ethers used in solid-liquid phase-transfer catalysis.The potassium carbonate-Carbowax combination allows the generation of anions up to pKa of ca. 12.The catalysis mechanism is discussed and the synthesis of several ethers and thioethers is reported, some of which are obtained only with difficulty by normal liquid-liquid phase-transfer catalysis.
- Angeletti, Enrico,Tundo, Pietro,Venturello, Paolo
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p. 1137 - 1142
(2007/10/02)
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