- Improved preparation method for 2,5-disubstituted benzyl chloride
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The invention relates to an improved preparation method for 2,5-disubstituted benzyl chloride. The improved preparation method is characterized in that the 2,5-disubstituted benzyl chloride is prepared through a reaction as described in the specification. In the reaction, R and R each independently represent a C1-10 alkyl group, preferably a C1-6 alkyl group, and most preferably a methyl group. The method comprises the following steps: reacting paraformaldehyde with concentrated hydrochloric acid, adding p-disubstituted benzene, carrying out gradient heating, conducting heating to 50-65DEG C at first, carrying out reacting at the temperature for 1-3 hours, then conducting heating to 75-90 DEG C, and carrying out reacting for 6-10 hours at the temperature.
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Paragraph 0036-0044
(2020/07/15)
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- Method for preparing 2, 5-dimethylphenylacetyl chloride
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The invention discloses a method for preparing 2, 5-dimethylphenylacetyl chloride, and belongs to the field of pesticide intermediate synthesis. According to the method, p-xylene is used as an initialraw material, chloromethylation, cyaniding, hydrolysis and acylating chlorination are carried out, 2, 5-dimethylphenylacetyl chloride is obtained after continuous reaction without purification, the total yield of the four steps of reaction is 75%, and the product purity is greater than 99.0%. The method is simple in process and only needs to purify the final product and is low in operation cost,mild in reaction condition and high in yield and product purity and is very easy to realize industrial production.
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Paragraph 0040-0042; 0049-0051; 0058-0059; 0066-0067
(2020/05/08)
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- Ir-Catalyzed Asymmetric and Regioselective Hydrogenation of Cyclic Allylsilanes and Generation of Quaternary Stereocenters via the Hosomi-Sakurai Allylation
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A number of cyclic dienes containing the allylsilane moiety were prepared by a Birch reduction and subjected to iridium-catalyzed regioselective and asymmetric hydrogenation, which provided chiral allylsilanes in high conversion and enantiomeric excess (up to 99 % ee). The compounds were successively used in the Hosomi–Sakurai allylation with various aldehydes employing TiCl4 as Lewis acid, providing adducts with two additional stereogenic centers in excellent diastereoselectivity.
- Rabten, Wangchuk,Margarita, Cristiana,Eriksson, Lars,Andersson, Pher G.
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supporting information
p. 1681 - 1685
(2018/01/05)
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- METHOD FOR PREPARING 2,5-DIMETHYLPHENYLACETIC ACID
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Provided is a method for preparing 2,5-dimethylphenylacetic acid, wherein p-xylene is mixed with paraformaldehyde and concentrated hydrochloric acid in a solvent of ion liquid to obtain 2,5-dimethyl benzyl chloride by the chloromethylation reaction. Then, 2,5-dimethyl benzyl chloride is introduced into a reactor with an acid binding agent and a solvent, the carbonylation and hydrolysis reaction is conducted in the presence of a catalyst to obtain 2,5-dimethylphenylacetic acid. The present process has new route, less synthesis steps, simple operation, lower cost, increased yield, and is friendly to the environment. Therefore, the method is suitable for industrial production.
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Paragraph 0036; 0037
(2013/03/26)
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- A METHOD FOR PREPARING 2,5-DIMETHYLPHENYLACETIC ACID
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Provided is a method for preparing 2,5-dimethylphenylacetic acid, wherein p-xylene is mixed with paraformaldehyde and concentrated hydrochloric acid in a solvent of ion liquid to obtain 2,5-dimethyl benzyl chloride by the chloromethylation reaction. Then, 2,5-dimethyl benzyl chloride is introduced into a reactor with an acid binding agent and a solvent, the carbonylation and hydrolysis reaction is conducted in the presence of a catalyst to obtain 2,5-dimethylphenylacetic acid. The present process has new route, less synthesis steps, simple operation, lower cost, increased yield, and is friendly to the environment. Therefore, the method is suitable for industrial production.
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Paragraph 0022
(2013/03/26)
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- An experimental and theoretical study on imidazolium-based ionic liquid promoted chloromethylation of aromatic hydrocarbons
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The chloromethylation of aromatic hydrocarbons proceeded efficiently using the reusable imidazolium-based ionic liquid as promoter. Mild reaction conditions, enhanced rates, improved yields, recyclability of ionic liquids, and reagents' reactivity which is different from that in conventional organic solvents are the remarkable features observed in ionic liquids. The ionic liquids were recycled in three subsequent runs with no decrease in activity. In addition, the results of calculations with the Gaussian 98 suite of program are in good accordance with the experimental outcomes.
- Wang, Yun,Xi, Yanli
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p. 2196 - 2199
(2014/03/21)
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- Condensation reactions of planar chiral tricarbonyl-chromium-complexed benzylic alcohols and acetates with reactive arenes
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The condensation reaction of planar chiral 2- and 2,5-substituted tricarbonyl-chromium complexed benzylic alcohols and acetates with reactive arenes (durene, anisole, 1,3-dimethoxybenzene, diphenyl ether) is reported. The reactions were performed in both racemic and enantiomeric versions, optically pure and S-(-)-[2-methoxybenzyl alcohol]-tricarbonyl-chromium being prepared by LiAlH4 reduction of diastereomeric, t.l.c. separated, (-)-menthyl esters of [2-methoxybenzoic acis]-tricarbonyl-chromium. The condensation of the difunctional complex [1,4-diacetoxymethylene-2,5-dimethoxybenzene]-tricarbonyl- chromium with an excess of anisole proved the same reactivity at both reactive benzylic sites thus serving as a model for possible polycondensation process. Corresponding optically pure difunctional starting complexes were obtained by t.l.c. separation of diasteromeric diesters with R-(-)-lactic or S-(-)-mandelic acids.
- Rosca, Sorin I.,Stan, Raluca,Ott, Cristina,Parlea, Elena
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scheme or table
p. 327 - 333
(2011/04/27)
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- An inexpensive and convenient procedure for chloromethylation of aromatic hydrocarbons by phase transfer catalysis in aqueous media
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Reaction of aromatic hydrocarbons catalyzed by a novel catalytic system consisting of zinc chloride, acetic acid, sulfuric acid and PEG-800 in aqueous media under PTC conditions results in chloromethylation in good to excellent yield.
- Hu, Yu Lin,Lu, Ming,Ge, Qiang,Wang, Peng Cheng,Zhang, Sheng Bin,Lu, Ting Ting
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experimental part
p. 97 - 102
(2010/08/05)
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- Paracyclophanes. Part 58 [1]. On the use of the stilbene-phenanthrene photocyclization in [2.2]paracyclophane chemistry
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The application of the stilbene→phenanthrene photocyclization to [2.2]paracyclophane chemistry has been investigated. For the model system 4-styryl[2.2]paracyclophane (2) to [2.2]phenanthrenoparacyclophane (3) the reaction allows the introduction of alkyl substituants in the 6-, 7-, 8- and 9-position of the phenanthrene moiety. However, when the substituent in the 9-position (bay area of phenanthrene nucleus) becomes too large, viz. tert-butyl, no ring closure is observed anymore. The side products of the process (ring cleavage products of the cyclophane core such as 9 and 10) have been characterized for the first time. Extension of the condensed deck is possible leading to PAH-phanes as demonstrated by the preparation of the chrysenophanes 45 and 60; the cyclization to novel helicenophanes such as 50 also takes place without difficulties. In the case of 1,2-di(4-[2.2] paracyclophanyl)ethene (63) the triply-layered hydrocarbon 65 is produced on irradiation in small amounts.
- Hopf,Hucker,Ernst
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p. 947 - 969
(2008/09/17)
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- Chlorination and oxidation products formed from 1,2,4-trimethylbenzene in aqueous solution under the action of chlorine dioxide
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Products of the reaction of 1,2,4-trimethylbenzene with chlorine dioxide in aqueous solution were studied. A scheme of 1,2,4-trimethylbenzene transformations was suggested. The influence exerted on the number of the reaction products by the ClO2 dosage and time of its contact with the substrate was examined.
- Khasanova,Vozhdaeva,Kabal'nova,Kantor
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p. 1105 - 1110
(2008/04/05)
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- Identification of alkylarene chloromethylation products using gas-chromatographic retention indices
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Gas-chromatographic retention indices on standard nonpolar polydimethylsiloxane stationary phases allow identification of products formed by known organic reactions even without using mass-spectrometric data. The efficiency of this approach was demonstrated by the example of identification of previously uncharacterized chloromethyl derivatives of alkylarenes, including structural isomers of compounds containing several chloromethyl groups, directly in reaction mixtures. Chromatographic analysis of such reaction mixtures allows identification of positional isomers of the starting alkylarenes even when they are present simultaneously. The retention indices were determined for the first time for more than 50 alkyl-(chloromethyl)arenes, by-products of chloromethylation, and chloromethyl derivatives of the simplest alkyl phenyl ketones. Nauka/Interperiodica 2007.
- Zenkevich,Makarov
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p. 611 - 619
(2008/03/18)
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- [emim]BF4-promoted chloromethylation of aromatic hydrocarbons
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The chloromethylation of aromatic hydrocarbons proceeded efficiently using the reusable ionic liquid [emim]BF4 as promoter. The reactions were completed in 5 h at 70°C with good yields and easy workup. Copyright Taylor & Francis Group, LLC.
- Wang, Yun,Shang, Zhi-Cai,Wu, Tian-Xing
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p. 3053 - 3059
(2007/10/03)
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- Interpretation of retention indices in gas chromatography for establishing structures of isomeric products of alkylarenes radical chlorination
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By an example of previously uncharacterized products obtained by alkylarenes radical chlorination was demonstrated that combination of various interpretation methods applied to the retention indices (RI) in the gas chromatography on the standard nonpolar phases (comparison of RI of products and initial compounds, characteristics of succession of the chromatographic elution of the structural isomers with the use of estimation of molecular dynamic parameters, application of the additive schemes to RI calculation, and using of structural analogy CH3?Cl for testing the results obtained) permitted unambiguous identification of the structure even without data of mass spectrometry.
- Zenkevich
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p. 270 - 280
(2007/10/03)
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- Photocyclization of -(o-Tolyl)acetophenones: Triplet and 1,5-biradical reactivity
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Several ring-substituted α-(o-tolyl)acetophenones undergo photocyclization to 2-indanol derivatives in high quantum efficiency in solution and in high chemical yield as solids. The mechanism for reaction involves triplet state δ-hydrogen atom abstraction that generates 1,5-biradicals. Quenching studies indicate that the n.π* excited triplets of these ketones react, with rate constants >108 s-1. Variations in triplet reactivity are ascribed to conformational equilibria that populate reactive and unreactive geometries to different extents. The α-aryl ring eclipses the carbonyl in the lowest energy geometry, from which the most favorable geometry for reaction can be reached by small bond rotations. α-(2,4,6-Triisopropylpheny)acetophenone forms the relatively long lived enol as well as indanol in solvent-dependent ratios; deuterium labeling indicates that the 1,5-biradical disproportionates to form enol. This does not happen with α-mesitylacetophenone, so its 54% cyclization quantum efficiency is ascribed to an internal triplet quenching that competes with hydrogen abstraction. This internal quenching is presumed to be of the charge-transfer type and does not appear to lead directly to 1,5-biradicals. 1-Methyl-2-phenyl-2-indanol is formed from α-(o-ethylpheny)acetophenone with a Z/E ratio of 20:1 in benzene and 2:1 in methanol. The 1,5-biradical intermediates were characterized by flash spectroscopy; they have lifetimes between 15 and 45 ns, with those derived from α-(o-isopropylphenyl) ketones being twice as long-lived as those derived from α-(o-methylphenyl) ketones, and show only a small solvent dependence. Biradical lifetimes and the diastereoselectivity of cyclization are interpreted in terms of biradical intersystem crossing occurring preferentially along the reaction coordinate for cyclization, such that the two processes effectively occur concurrently. The applicability of this concept to other biradicals is discussed.
- Wagner, Peter J.,Meador, Michael A.,Zhou, Boli,Park, Bong-Ser
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p. 9630 - 9639
(2007/10/02)
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- An N.M.R. Investigation of the Mills-Nixon Effect
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The 4J coupling constant, previously established as a probe of bond order, was used to examine the bond orders in a series of ortho-bridged compounds: benzocyclopropene, 1,2-dihydrobenzocyclobutene, indan and tetralin.No evidence for sterically induced bond fixation (i.e. the Mills-Nixon effect) was found, but some evidence for electronic distortion in the corresponding benzylic ketones was observed.The experimental results are in accord with SCF/MO calculations.
- Collins, Michael J.,Gready, Jill E.,Sternhell, Sever,Tansey, Charles W.
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p. 1547 - 1557
(2007/10/02)
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- ALKALOIDS OF Nitraria schoberi. STRUCTURE OF NITRARAINE
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The dehydration of nitraraine leads to the formation of 1-(2',6'-dimethylbenzyl)-β-carboline, together with other products.Several isomeric 1-(dimethylbenzyl)-β-carbolines have been synthesized for comparison.The products of acylation, hydrogenation, and oxidation of the alkaloid nitraraine have been studied.The results obtained have shown its structure as (+/-)-16-hydroxymethylyohimb-16-ene.
- Ibragimov, A. A.,Yunusov, S. Yu.
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p. 502 - 509
(2007/10/02)
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- ARYLMETHYL ISOCYANATES
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Chloromethyl isocyanate reacts readily with aromatic hydrocarbons in the presence of anhydrous ferric chloride or other catalysts of the Friedel-Crafts reaction with the formation of arylmethyl isocyanates.The latter add alcohols and amines readily, being converted into the corresponding substituted urethanes and ureas.When heated in the presence of catalytic amounts of 1,3-dimethylphosphol-3-ene they give substituted carbodiimides.
- Kozhushko, B. N.,Lomakina, A. V.,Paliichuk, Yu. A.,Shokol, V. A.
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p. 654 - 660
(2007/10/02)
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- New Approach to the Mechanism of the Reaction between Benzyl Grignard Reagents and Carbonyl Compounds
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The reaction of the magnesium chloride with ketones can lead to the formation of ortho alcohols 4, normal alcohols 3, or enolates.We propose a mechanism for the reaction whose first step, as in the case of aldehydes, is a reversible attack of the ketone at the ortho position of the benzylic Grignard reagent, which can then lead to the formation of the normal alcohol and/or enolate.The fact that benzylmagnesium chloride reacts with cyclobutanone to give a diol analogous to that obtained in reactions with aldehydes, while its reaction with 1,1,1-trifluoro-2-propanone does not give a diol, leads us to propose an interpretation involving steric effects in the rearrangement alkoxide.In the case of ketones, these steric interactions generally prevent the Prins-type reaction leading to diols.
- Bernardon, Claude,Deberly, Alain
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p. 463 - 468
(2007/10/02)
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