- Milled Dry Ice as a C1 Source for the Carboxylation of Aryl Halides
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The use of carbon dioxide as a C1 chemical feedstock remains an active field of research. Here we showcase the use of milled dry ice as a method to promote the availability of CO 2in a reaction solution, permitting practical synthesis of arylcarboxylic acids. Notably, the use of milled dry ice produces marked increases in yields relative to those obtained with gaseous CO 2, as previously reported in the literature.
- O'Brien, Connor J.,Nicewicz, David A.
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supporting information
p. 814 - 816
(2021/03/01)
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- Magnesiation of Aryl Fluorides Catalyzed by a Rhodium-Aluminum Complex
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We report the magnesiation of aryl fluorides catalyzed by an Al-Rh heterobimetallic complex. We show that the complex is highly reactive to cleave the C-F bonds across the polarized Al-Rh bond under mild conditions. The reaction allows the use of an easy-to-handle magnesium powder to generate a range of arylmagnesium reagents from aryl fluorides, which are conventionally inert to such metalation compared with other aryl halides.
- Fujii, Ikuya,Semba, Kazuhiko,Li, Qiao-Zhi,Sakaki, Shigeyoshi,Nakao, Yoshiaki
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supporting information
p. 11647 - 11652
(2020/08/06)
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- CO2 (De)Activation in Carboxylation Reactions: A Case Study Using Grignard Reagents and Nucleophilic Bases
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Carbon dioxide (CO2) is an intrinsically stable molecule. However, its reactivity toward nucleophilic bases has constituted an appealing characteristic for applications such as CO2 capture and functionalization. To shed light on the role of nucleophilic bases in CO2 functionalization, we performed some mechanistic studies using nitrogen-containing bases as an additive-in catalytic amounts-for carboxylation reactions of Grignard reagents. Our kinetic analysis and in situ infrared spectroscopy revealed the role of nucleophilic bases, particularly that of DBU (1,8-diazabicycloundec-7-ene), in CO2 (de)activation for carboxylation reactions.
- Valera Lauridsen, Jerik Mathew,Cho, Sung Yeon,Bae, Han Yong,Lee, Ji-Woong
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supporting information
p. 1652 - 1657
(2020/03/30)
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- Method for copper-catalyzed carboxylation reaction of arylboronic acid and carbon dioxide
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The invention discloses a method for a copper-catalyzed carboxylation reaction of arylboronic acid and carbon dioxide. According to the method, carbon dioxide is used as a C1 source, copper catalysisis adopted, alkoxide serves as alkali, and a reaction is carried out in an organic solvent; the method is simple in process and easy to implement, and shows wide functional group compatibility; the method allows various arylboronic acids such as monosubstituted or polysubstituted phenylboronic acid, polycyclic aromatic hydrocarbon boronic acid and benzoheterocyclic boronic acid to be converted into corresponding arylcarboxylic acids with considerable yield under mild conditions; and the produced carboxylic acids have important application value, and can be used for deriving a great number of other common chemical substances, such as acyl halide, acid anhydride, ester and amide.
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Paragraph 0087; 0088
(2019/12/29)
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- Nickel-Catalyzed Ortho C–H Methylation of Aromatic Amides with Di-tert-butyl Peroxide as Methylation Reagent
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A new efficient protocol for the ortho-methylation of benzamides with DTBP has been developed via Ni(II)-catalyzed C–H activation directed by 8-aminoquinoline. This method is performed under base-free, ligand-free conditions and utilizes cheap and commercially available reagents. Moreover, the by-product acetone derived from DTBP does not affect the purification of the product.
- Liu, Da,Yu, Lin,Yu, Yongqi,Xia, Zhen,Song, Zenan,Liao, Lihong,Tan, Ze,Chen, Xiang
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supporting information
p. 6930 - 6934
(2019/11/13)
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- Preparation method for o-tolylacetic acid aryl formic acid derivative
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The invention discloses a preparation method for an o-tolylacetic acid aryl formic acid derivative. According to the method, new C-C bonds can be formed, the organic o-tolylacetic acid aryl formic acid derivative is obtained, the good functional group tolerance is achieved, and the o-tolylacetic acid aryl formic acid derivative which cannot be easily obtained by adopting other methods can be synthesized; according to the method, adopted raw materials are easy to obtain, the yield is high, the reaction conditions are mild, the substrate range is wide, and after-treatment is simple and green.
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Paragraph 0044-0047
(2019/07/16)
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- Palladium-Catalyzed ortho-C-H Methylation of Benzoic Acids
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A palladium-catalyzed methylation of C-H bonds of benzoic acids with di-tert-butyl peroxide as the methylating reagent under an external oxidant and ligand-free conditions has been achieved. The reaction is found to be directed by a weakly coordinating carboxyl group, offering a facile route for the synthesis of highly functionalized ortho-methyl benzoic acids.
- Lv, Weiwei,Wen, Si,Liu, Jing,Cheng, Guolin
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p. 9786 - 9791
(2019/08/26)
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- Site- and regio-selective incorporation of carbon dioxide into the C(sp2)Si bond of benzosilacyclobutenes
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A reaction of benzosilacyclobutenes with carbon dioxide is catalyzed by a nickel complex having an N-heterocyclic carbene ligand. Carbon dioxide inserts into the C(sp2)Si bond in a site- and regio-selective manner to form a carboncarbon bond, furnishing benzoic acid derivatives.
- Ishida, Naoki,Okumura, Shintaro,Murakami, Masahiro
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supporting information
p. 570 - 572
(2018/04/12)
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- Room Temperature Carbonylation of (Hetero) Aryl Pentafluorobenzenesulfonates and Triflates using Palladium-Cobalt Bimetallic Catalyst: Dual Role of Cobalt Carbonyl
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An efficient method for the carbonylation of (hetero) aryl pentafluorobenzenesulfonates and triflates under exceptionally mild conditions using palladium/dicobalt octacarbonyl [Pd/Co2(CO)8] has been developed. Besides acting as carbon monoxide (CO) source, Co2(CO)8enhances the reaction rate by accelerating the CO insertion through an in situ generated bimetallic palladium cobalt tetracarbonyl [Pd-Co(CO)4] complex. Under the optimized reaction condition, carbonylation of a wide range of activated and deactivated, as well as sterically hindered and heteroaromatic, substrates proceeded efficiently at room temperature. The high chemoselectivity and improved synthesis of biologically relevant Isoguvacine and Lazabemide intermediates highlights its scope as a valuable synthetic method. The generality of this protocol was further extended to other electrophiles (bromides, chlorides and tosylates). (Figure presented.).
- Joseph, Jayan T.,Sajith, Ayyiliath M.,Ningegowda, Revanna C.,Shashikanth, Sheena
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p. 419 - 425
(2017/02/10)
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- Iron-Catalyzed Ortho C-H Methylation of Aromatics Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand
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Iron-catalyzed C-H functionalization of aromatics has attracted widespread attention from chemists in recent years, while the requirement of an elaborate directing group on the substrate has so far hampered the use of simple aromatic carbonyl compounds such as benzoic acid and ketones, much reducing its synthetic utility. We describe here a combination of a mildly reactive methylaluminum reagent and a new tridentate phosphine ligand for metal catalysis, 4-(bis(2-(diphenylphosphanyl)phenyl)phosphanyl)-N,N-dimethylaniline (Me2N-TP), that allows us to convert an ortho C-H bond to a C-CH3 bond in aromatics and heteroaromatics bearing simple carbonyl groups under mild oxidative conditions. The reaction is powerful enough to methylate all four ortho C-H bonds in benzophenone. The reaction tolerates a variety of functional groups, such as boronic ester, halide, sulfide, heterocycles, and enolizable ketones.
- Shang, Rui,Ilies, Laurean,Nakamura, Eiichi
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supporting information
p. 10132 - 10135
(2016/08/31)
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- Inclusion complex containing epoxy resin composition for semiconductor encapsulation
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The invention is an epoxy resin composition for sealing a semiconductor, including (A) an epoxy resin and (B) a clathrate complex. The clathrate complex is one of (b1) an aromatic carboxylic acid compound, and (b2) at least one imidazole compound represented by formula (II): wherein R2 represents a hydrogen atom, C1-C10 alkyl group, phenyl group, benzyl group or cyanoethyl group, and R3 to R5 represent a hydrogen atom, nitro group, halogen atom, C1-C20 alkyl group, phenyl group, benzyl group, hydroxymethyl group or C1-C20 acyl group. The composition has improved storage stability, retains flowability when sealing, and achieves an effective curing rate applicable for sealing delicate semiconductors.
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- Method for estimating SN1 rate constants: Solvolytic reactivity of benzoates
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Nucleofugalities of pentafluorobenzoate (PFB) and 2,4,6-trifluorobenzoate (TFB) leaving groups have been derived from the solvolysis rate constants of X,Y-substituted benzhydryl PFBs and TFBs measured in a series of aqueous solvents, by applying the LFER equation: log k = sf(Ef + Nf). The heterolysis rate constants of dianisylmethyl PFB and TFB, and those determined for 10 more dianisylmethyl benzoates in aqueous ethanol, constitute a set of reference benzoates whose experimental ΔG ? have been correlated with the ΔH? (calculated by PCM quantum-chemical method) of the model epoxy ring formation. Because of the excellent correlation (r = 0.997), the method for calculating the nucleofugalities of substituted benzoate LGs have been established, ultimately providing a method for determination of the SN1 reactivity for any benzoate in a given solvent. Using the ΔG? vs ΔH? correlation, and taking sf based on similarity, the nucleofugality parameters for about 70 benzoates have been determined in 90%, 80%, and 70% aqueous ethanol. The calculated intrinsic barriers for substituted benzoate leaving groups show that substrates producing more stabilized LGs proceed over lower intrinsic barriers. Substituents on the phenyl ring affect the solvolysis rate of benzhydryl benzoates by both field and inductive effects.
- Matic, Mirela,Denegri, Bernard,Kronja, Olga
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supporting information
p. 8986 - 8998,13
(2012/12/12)
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- Direct carboxylation of arenes and halobenzenes with CO2 by the combined use of AlBr3 and R3SiCl
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The Lewis acid-mediated direct carboxylation of aromatic compounds with CO2 is efficiently promoted by the addition of silyl chlorides bearing three alkyl and/or aryl substituents in total on the silicon atom. Thus, toluene, xylenes, mesitylene, and some other alkylbenzenes are treated with a 1:1 mixture of AlBr3 and Ph3SiCl in neat substrates under CO2 pressure (3.0 MPa) at room temperature, to give the corresponding carboxylic acids in 60-97% yields, based on AlBr3. Polycyclic arenes, including naphthalene, phenanthrene, and biphenyl, are regioselectively carboxylated in 91-98% yields with the aid of 1 molar equiv of AlBr3 and Ph3SiCl in an appropriate solvent, chosen from benzene, chlorobenzene, and fluorobenzene. These solvents, as well as bromobenzene, resist carboxylation; however, they are also carboxylated in moderate yields when treated with a 1:5 mixture of AlBr3 and iPrSiCl at elevated temperatures. The FT-IR spectrum of a mixture prepared by exposing a suspension of AlBr3 and Ph3SiCl in cyclohexane to CO 2 exhibits an absorption band around 1650 cm-1, assigned to the C=O stretching vibration of a species consisting of CO2, AlBr3, and Ph3SiCl, which suggests that the silyl chlorides activate CO2 in cooperation with AlBr3. 1H NMR analysis of unworked-up reaction mixtures reveals that the products merge as aluminum carboxylates. The mass balance concerning silicon indicates that the silyl chlorides are recycled during the reaction sequence. On the basis of these observations, a feasible mechanism is proposed for the present carboxylation.
- Nemoto, Koji,Yoshida, Hiroki,Egusa, Naoki,Morohashi, Naoya,Hattori, Tetsutaro
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experimental part
p. 7855 - 7862
(2011/02/21)
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- 2,6-Dimethyl-4-nitrobenzoic anhydride (DMNBA): An effective coupling reagent for the synthesis of carboxylic esters and lactones
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Various carboxylic esters are obtained at room temperature in excellent yields with high chemoselectivities from nearly equimolar amounts of carboxylic acids and alcohols using 2,6-dimethyl-4-nitrobenzoic anhydride with triethylamine by the promotion of 4-(dimethylamino)pyridine. The efficiency of the esterification is compared to those of other dehydrations using substituted benzoic anhydrides as coupling reagents. This method was successfully applied to the synthesis of threo-aleuritic acid lactone and the desired 17-membered ring compound was prepared in high yield at room temperature from the corresponding free trihydroxycarboxylic acid using 2,6-dimethyl-4-nitrobenzoic anhydride in the presence of 4-(dimethylamino)pyridine.
- Shiina, Isamu,Miyao, Ryo
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experimental part
p. 1313 - 1328
(2009/07/05)
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- Palladium-catalyzed methylation and arylation of sp2 and sp 3 C-H bonds in simple carboxylic acids
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The use of preformed sodium carboxylates as substrates led to the first observation of facile Pd-insertions into sp3 β-C-H bonds in simple aliphatic acids. Consequently, Pd-catalyzed methylation and arylation of o-C-H bonds in benzoic acids and β-C-H bonds in aliphatic acids using either a phenylboronate, methylboronic acid, or ArI have been achieved via a C-H activation/C-C coupling sequence. Copyright
- Giri, Ramesh,Maugel, Nathan,Li, Jiao-Jie,Wang, Dong-Hui,Breazzano, Steven P.,Saunders, Lindsey B.,Yu, Jin-Quan
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p. 3510 - 3511
(2007/10/03)
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- Aerobic oxidation of trimethylbenzenes catalyzed by N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst
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The oxidation of trimethylbenzenes was examined with air or O2 using N,N′,N″-trihydroxyisocyanuric acid (THICA) as a key catalyst. Thus, 1,2,3-, 1,2,4-, and 1,3,5-trimethylbenzenes under air (20 atm) in the presence of THICA (5 mol %), Co(OAc)2 (0.5 mol %), Mn(OAc)2, and ZrO(OAc)2 at 150 °C were oxidized to the corresponding benzenetricarboxylic acids in good yields (81-97%). In the aerobic oxidation of 1,2,4-trimethylbenzene by the THICA/Co(II)/Mn(II) system, remarkable acceleration was observed by adding a very small amount of ZrO(OAc)2 to the reaction system to form 1,2,4-benzenetricarboxylic acid in excellent yield (97%). In contrast, no considerable addition effect was observed in the oxidation of 1,3,5-trimethylbenzene. This aerobic oxidation by the present catalytic system provides an economical and environmentally benign direct method to benzenetricarboxylic acids, which are very important polymer materials.
- Hirai, Naruhisa,Tatsukawa, Yoshinobu,Kameda, Michiko,Sakaguchi, Satoshi,Ishii, Yasutaka
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p. 6695 - 6699
(2007/10/03)
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- Solvolysis of benzyl alcohols and ethers in 1,2-diols and application to a deprotection of benzyl ether-type protecting groups
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Some kinds of benzyl alcohols and ethers react with 1,2-diols, such as ethylene glycol and propylene glycol, at 130-190°C to give 2-hydroxyethyl or 2-hydroxypropyl ethers. Application of this reaction to a deprotection of benzyl ether-type protecting groups, under neutral conditions, was also described. Copyright
- Miyake, Hideyoshi,Fujimura, Masahiro,Tsumura, Takatsugu,Sasaki, Mitsuru
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p. 778 - 779
(2007/10/03)
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- An efficient Pd(II)-based catalyst system for carboxylation of aromatic C-H bond by addition of a phosphenium salt
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Addition of a phosphenium dramatically improved the reaction yields in the carboxylation of arenes by formic acid catalyzed by Pd(II). Control experiments revealed that the majority of the phosphenium triflate was converted to a mixed anhydride of phosphonic acid and formic acid (7), which however did not substitute for the phosphenium to improve the reaction yield.
- Sakakibara, Ken,Yamashita, Makoto,Nozaki, Kyoko
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p. 959 - 962
(2007/10/03)
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- Aromatic Spiranes XXI [1]: Syntheses of Methyl Substituted Phthalaldehydic Acids and their Ethyl and Methyl Esters as Synthones for Syntheses of Methylated 2,2′-Spirobiindandiones
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The isomeric methyl phthalaldehydic acids 11 were obtained from phthalides 4 by bromation (NBS) to the 3-bromo derivatives 7 and subsequent hydrolysis with water. 4 in turn were accessible from dimethyl methyl benzoates 1 by dibromination with NBS and subsequent thermical cyclization to the bromo derivatives 3 which, on catalytic dehalogenation, afforded the phthalides 4. Reaction of 11 with methanol or ethanol gave the pseudo-esters 13 and 14, resp. Short treatment of 11 with diazomethane on the other hand yielded the methyl formyl benzoates 15b to 15e. Prolonged reaction (several hours) gave the oxiranyl compounds 17; in addition, the acetonyl derivatives 18 were also found, obviously formed by a double methylene insertion into 15. All reactions proceeded with good to excellent yields.
- Neudeck
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p. 201 - 217
(2007/10/03)
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- Structural and Solvent Effects upon Decarboxylation of 2,6-Disubstituted Benzoyloxyl Radicals. A Laser Flash Photolysis Study of Bis(2,6-disubstituted-benzoyl) Peroxides
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The rate constants for decarboxylation of 2,6-dimethylbenzoyloxyl, 2,4,6-trimethylbenzoyloxyl and 2,6-dichlorobenzoyloxyl radicals are larger than those of benzoyloxyl, 4-methylbenzoyloxyl and 2-chlorobenzoyloxyl radicals, respectively, in carbon tetrachloride and acetonitrile; however, the values in the former solvent are significantly larger than those in the latter.The rate acceleration with the ortho substituents is ascribed to a nonplanar geometry of the radicals brought about by twisting of the carbonyloxyl group due to a steric effect of the substituents.The polar solvent serves to stabilize a twisted charge-transfer structure of the radicals and retards their decarboxylation.
- Wang, Jun,Itoh, Hiroki,Tsuchiya, Masahiro,Tokumaru, Katsumi,Sakuragi, Hirochika
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p. 11967 - 11978
(2007/10/02)
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- Behavior of 2-substituted and 2,6-disubstituted benzoyloxyl radicals. Electronic and steric effects of the substituents
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In contrast to 2-methylbenzoyloxyl radicals, 2,6-dimethylbenzoyloxyl and 2,4,6-trimethyl-benzoyloxyl radicals decarboxylate efficiently rather than transfer a hydrogen atom, as observed by transient absorption spectroscopy and product distribution.
- Wang,Wang, Jun,Tsuchiya,Tsuchiya, Masahiro,Sakuragi,Sakuragi, Hirochika,Tokumaru,Tokumaru, Katsumi,Itoh,Itoh, Hiroki
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p. 6321 - 6324
(2007/10/02)
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- RAPID SOLVOLYSES OF 2,6-DIMETHYL- AND 2,4,6-TRIMETHYL-BENZOYL CHLORIDES: MODEL SYSTEMS FOR SOLVENT EFFECTS ON THE REACTIVITY OF ACID CHLORIDES
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Rates of solvolyses of 2,6-dimethyl- and 2,4,6-trimethyl-benzoyl (mesitoyl) chlorides are reported for aqueous binary mixtures with acetone, ethanol, and methanol.These data are compared with those obtained for solvolyses of p-methoxybenzoyl (anisoyl) chloride.A consistent definition of selectivity is proposed to remove ambiguities in published values.Selectivities (S) for formation of ester relative to acid in alcohol-water mixtures are almost independent of solvent composition and are inverse for ethanol mixtures; methanol mixtures show higher S values.Acid catalysis does not appear to be significant.The results show that, for solvolyses of acid chlorides, a solvation effect and possibly a mass law effect increase the reaction rates in methanol-water mixtures as compared with those in ethanol-water mixtures having the same Y value.Differences between the mechanism of solvolyses of mesitoyl and anisoyl chlorides are revealed by rate enhancements with added m-nitroaniline, and by a comparison of m-values.Experience of recent conductimetric studies of a wide range of relatively rapid solvolytic rections is summarised.
- Bentkey, T. William,Harris, H. Carl,Koo, In Sun
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p. 783 - 790
(2007/10/02)
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- Vinyl Cation Intermediates in Solvolytic and Electrophilic Reactions. 1. Solvolysis of α-Arylvinyl Derivatives
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The solvolysis of 16 α-arylvinyl tosylates, bromides, and chlorides has been investigated in various alcohol-water mixtures and in acetic acid at several temperatures.All substrates were substituted with either 2-methyl or 2,6-dimethyl groups to accelerate the rates of reaction.The major or exclusive product isolated in most cases was the acetophenone arising from hydrolysis of the expected enol ethers or acetates during workup.The kinetics were simple first order in the vast majority of cases, with excess base added to prevent side reactions.Leaving group effects, Winstein-Grunwald m values, Schleyer Q values, and effects of solvent nucleophilicity all point to a limiting SN1 ionization generating a vinyl cation intermediate, in which there is little rear-side nucleophilic assistance by solvent.Substituent effects led to ρ values in the range -3.9 to -5.3 vs. ?+.Activation parameters are typical for an SN1 process, and ΔS% is insensitive to the presence of zero, one, or two o-methyl groups, as are the effects of solvent polarity on the rates.The results should therefore be directly comparable with other solvolytic or electrophilic reactions generating formally similar vinyl cation intermediates.
- Yates, Keith,Mandrapilias, George
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p. 3892 - 3902
(2007/10/02)
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- Reaction of Diazonium Salts with Transition Metals. 4. Palladium(0)-Catalyzed Carboxylation of Arenediazonium Salts
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Various arylamines were converted to arenecarboxylic acids in good yields via their diazonium tetrafluoroborates by reaction with carbon monoxide (9 kg/cm2) in the presence of a palladium(0) catalyst and sodium acetate.Evidence is presented which supports the idea that mixed anhydrides are initial products in the carboxylation.
- Nagira, Kazuhiko,Kikukawa, Kiyoshi,Wada, Fumio,Matsuda, Tsutomu
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p. 2365 - 2368
(2007/10/02)
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