- Gas-phase SN2 and E2 reactions of alkyl halides
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Rate coefficients have been measured for the gas-phase reactions of methyl, ethyl, n-propyl, isopropyl, tert-butyl, and neopentyl chlorides and bromides with the following set of nucleophiles, listed in order of decreasing basicity: HO-, CH3O-, F-, HO- (H2O), CF3CH2O-, H2NS-, C2F5CH2O-, HS-, and Cl-. For methyl chloride the reaction efficiency first falls significantly below unity with HO- (H2O) as the nucleophile and for methyl bromide with HS- as the nucleophile; in both cases the overall reaction exothermicity is about 30 kcal mol-1. Earlier conclusions that these halides react slowly with stronger bases are shown to be in error. In the region where the rates are slow oxygen anions react with the alkyl chlorides and bromides by elimination while sulfur anions of the same basicity react by substitution. This difference is due to a slowing down of elimination with the sulfur bases; sulfur anions show no increased nucleophilicity as compared to oxy anions of the same basicity. Rate coefficients have also been measured for reaction of methyl fluoride with HO- and CH3O- and ethylene oxide with HO-, CH3O-, and F-. All of these rates are slow but measurable; combining the results of these experiments with those of the alkyl chlorides and bromides suggests that the gas-phase barrier to the symmetrical SN2 reaction of F- with methyl fluoride is lower than previous estimates. We have also measured rates for reaction of allyl chloride with F-, H2NS-, and HS-, chloromethyl ether with H2NS- and HS-, chloroacetonitrile with F-, H2NS-, HS-, and 37Cl-, bromoacetonitrile with Cl- and 81Br-, and α-chloroacetone with H2NS-, HS-, and 37Cl-. Our results also imply that the gas-phase SN2 barrier for Br- reacting with methyl bromide is nearly equal to the ion-dipole attraction energy of the reactants, in agreement with previous estimates.
- DePuy, Charles H.,Gronert, Scott,Mullin, Amy,Bierbaum, Veronica M.
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- The Photolyses of 2,6- and 2,4-Difluorohalobenzenes
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Photolyses of 2,6- and 2,4-difluorobromobenzenes in acetonitrile gave isomerized and brominated products in addition to 1,3-difluorobenzene produced by the dehalogenation.The reactions were compared with similar reactions of the corresponding chloro- and iodoarenes.In general, photolytic cleavage of the C-X bond of 2,6-difluorohalo(X)benzene was shown to proceed more easily than the corresponding 2,4-difluorohalo compound.
- Song, Yong-Qi,Yuzuri, Tomoaki,Suezawa, Hiroko,Sakakibara, Kazuhisa,Hirota, Minoru,Nakada, Masahiro
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- Kinetics of the reactions of acetonitrile with chlorine and fluorine atoms
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The rate coefficients for the reactions of chlorine and fluorine atoms with acetonitrile have been measured using relative and direct methods. In the case of chlorine atoms the rate coefficient k1 was measured between 274 and 345 K using competitive chlorination and at 296 K using laser flash photolysis with atomic resonance fluorescence. The rate coefficient measured at ambient temperature (296 ± 2 K) is (1.15 ± 0.20) × 10-14 cm3 molecule-1 s-1, independent of pressure between 5 and 700 Torr (uncertainties are 2 standard deviations throughout). This result is a factor of 6 higher than the currently accepted value. The results from the three independent determinations reported here yield the Arrhenius expression k1 = (1.6 ± 0.2) × 10-11 exp[-(2140 ± 200)/T] cm3 molecule-1 s-1. Product studies show that the reaction of Cl atoms with CH3CN proceeds predominantly, if not exclusively, by hydrogen abstraction at 296 K. The rate coefficient for the reaction of fluorine atoms with acetonitrile was measured using both the relative rate technique and pulse radiolysis with time-resolved ultraviolet absorption spectroscopy. The rate coefficient for the reaction of F atoms with CH3-CN was found to be dependent on total pressure. The observed rate data could be fitted using the Troe expression with Fc = 0.6, k0 = (2.9 ± 2.1) × 10-28 cm6 molecule-2 s-1, and k∞ = (5.8 ± 0.8) × 10-11 cm3 molecule-1 s-1, with a zero pressure intercept of (0.9 ± 0.4) × 10-11 cm3 molecule-1 s-1. The kinetic data suggest that the reaction of F atoms with CH3CN proceeds via two channels: a pressure-independent H atom abstraction mechanism and a pressure-dependent addition mechanism. Consistent with this hypothesis, two products were observed using pulsed radiolysis with detection by UV absorption spectroscopy. As part of the product studies, relative rate techniques were used to measure k(Cl+CH2ClCN) = (2.8 ± 0.4) × 10-14 and k(F+CH2FCN) = (3.6 ± 0.2) × 10-11 cm3 molecule-1 s-1.
- Tyndall, Geoffrey S.,Orlando, John J.,Wallington, Timothy J.,Sehested, Jens,Nielsen, Ole J.
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- Photocatalytic C-H activation and the subtle role of chlorine radical complexation in reactivity
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The functionalization of methane, ethane, and other alkanes derived from fossil fuels is a central goal in the chemical enterprise. Recently, a photocatalytic system comprising [CeIVCl5(OR)]2- [CeIV, cerium(IV); OR, -OCH3 or -OCCl2CH3] was disclosed. The system was reportedly capable of alkane activation by alkoxy radicals (RO·) formed by CeIV-OR bond photolysis. In this work, we present evidence that the reported carbon-hydrogen (C-H) activation of alkanes is instead mediated by the photocatalyst [NEt4]2[CeCl6] (NEt4+, tetraethylammonium), and RO· are not intermediates. Spectroscopic analyses and kinetics were investigated for C-H activation to identify chlorine radical (Cl·) generation as the ratelimiting step. Density functional theory calculations support the formation of [Cl·][alcohol] adducts when alcohols are present, which can manifest a masked RO· character. This result serves as an important cautionary note for interpretation of radical trapping experiments.
- Yang, Qiaomu,Wang, Yu-Heng,Qiao, Yusen,Gau, Michael,Carroll, Patrick J.,Walsh, Patrick J.,Schelter, Eric J.
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p. 847 - 852
(2021/05/28)
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- Synthesis method of diethyl cyanomethylphosphonate
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The invention discloses a synthesis method of diethyl cyanomethylphosphonate. The synthesis method comprises the following steps: carrying out an esterification reaction on chloroacetic acid and ethanol to obtain ethyl chloroacetate; reacting the ethyl chloroacetate with ammonia water to generate chloroacetamide; adding phosphorus pentoxide into the chloroacetamide, performing heating dehydration,distilling out chloroacetonitrile while heating, and finally performing reduced pressure distillation to enable the chloroacetonitrile to be completely distilled out; transferring the chloroacetonitrile into a synthesis reaction kettle, adding a catalyst tetrabutylammonium iodide, heating, dropwise adding triethyl phosphite, and controlling the internal temperature for a reaction to obtain a crude product; and transferring the crude product into a high-purity rectifying tower, and performing purification to respectively rectify triethyl phosphite and diethyl cyanomethylphosphonate.
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Paragraph 0016-0017; 0020-0021; 0024-0025; 0028-0029
(2020/05/01)
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- New method for synthesis of chlorocyanomethane
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The invention discloses a new method for synthesis of chlorocyanomethane, and belongs to the technical field of synthesis. The method comprises the following steps: firstly, dissolving a compound rawmaterial with a general formula (II) in a solvent, then adding a chlorination reagent to carry out chlorination reaction, and at the end of the reaction, not treating the reaction liquid; and then adding a catalyst into water, adding the reaction liquid obtained at the end of the chlorination reaction into the water dropwise, carrying out hydrolysis decarboxylation reaction, and performing purification at the end of the reaction so as to obtain the chlorocyanomethane. The method has the advantages of mild reaction conditions, high product yield and good product quality.
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Paragraph 0049-0050
(2020/07/21)
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- Corresponding amine nitrile and method of manufacturing thereof
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The invention relates to a manufacturing method of nitrile. Compared with the prior art, the manufacturing method has the characteristics of significantly reduced using amount of an ammonia source, low environmental pressure, low energy consumption, low production cost, high purity and yield of a nitrile product and the like, and nitrile with a more complex structure can be obtained. The invention also relates to a method for manufacturing corresponding amine from nitrile.
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Paragraph 0153; 0154; 0155; 0160; 0161
(2018/05/07)
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- Synthetic method for methanesulfonic phentolamine drug intermediate chloroacetonitrile
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The invention relates to a synthetic method for methanesulfonic phentolamine drug intermediate chloroacetonitrile. The synthetic method includes the following steps that 6.3 mol of 1-chloro-2,2-dyhydroxyl ethylamine, 5.6 mol of cuprous chloride, 7.3-7.6 mol of a 2-amino bromobenzene solution and 300 ml of cyclohexane are added into a reaction container provided with a stirrer, a thermometer and a dropping funnel, the stirring speed is controlled to be 150-190 rpm, the solution temperature is raised to 90 DEG C-98 DEG C to carry out reaction for 5-7 h, the solution temperature is lowered to 70 DEG C-76 DEG C to continue to carry out reaction for 80-120 min, the solution temperature is lowered to 10 DEG C-16 DEG C, the solution stands for 8-10 h, and a solid is separated, filtered, washed with a saline solution, acetonitrile and ethanediamine, and dehydrated with a dehydrating agent, and distilled in a reduced pressure mode, and fraction at the temperature of 100 DEG C-108 DEG C is collected and recrystallized in dimethylamine to obtain crystal chloroacetonitrile.
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Paragraph 0014; 0015
(2016/11/09)
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- Phenyliodonium diacetate mediated direct synthesis of benzonitriles from styrenes through oxidative cleavage of C=C bonds
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A metal-free PhI(OAc)2 mediated nitrogenation of alkenes through C=C bond cleavage using inorganic ammonia salt as nitrogen source under mild conditions was developed, affording nitriles in moderate to good yields. The advantages of this reaction are mild reaction conditions, operational simplicity, and use of an ammonium salt as nitrogen source. Based upon experimental observations, a plausible reaction mechanism is proposed.
- Xu, Jin-Hui,Jiang, Qing,Guo, Can-Cheng
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p. 11881 - 11886
(2014/01/06)
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- Mechanism of halogen exchange in ATRP
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Detailed mechanistic studies reveal that halogen exchange (HE) in ATRP can occur not only by a radical pathway (atom transfer) but also by an ionic pathway (SN2 reaction) because Cu(I)(L)X and Cu (II)(L)X2 complexes contain weakly associated halide anion that can participate in the SN2 reaction with alkyl halide (ATRP initiator). Both pathways were kinetically studied, and their contributions to the HE process were quantitatively evaluated for seven alkyl halides and three Cu(I)(L)Cl complexes. Radical pathway dominates the HE process for 3° and 2° alkyl bromides with more active complexes such as Cu (I)(TPMA)Cl. Interestingly, ionic pathway dominates for 1° alkyl bromides and less active ATRP catalysts. These studies also revealed that degree of association of alkyl halide anion depends on the structure of copper complexes. In addition, radical pathway is accompanied by the reverse reactions such as deactivation of radicals to alkyl bromides and also activation of alkyl chlorides, reducing the efficiency of halogen exchange.
- Peng, Chi-How,Kong, Jing,Seeliger, Florian,Matyjaszewski, Krzysztof
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scheme or table
p. 7546 - 7557
(2012/07/28)
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- FUSED PYRIMIDINONE MATRIX METALLOPROTEINASE INHIBITORS
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Selective MMP-13 inhibitors are fused pyrimidinones of the formula or a pharmaceutically acceptable salt thereof, wherein: W, together with the carbon atoms to which it is attached, form a 5-membered ring diradical X is O, S, SO, SO2, NR5, or CH 2; B is O or NR5; or A and B are taken together to form--C≡C--; R1, R4, and R 5 are hydrogen, alkyl, alkenyl, alkynyl, (CH2)n aryl, (CH2)n cycloalkyl, C1-C6 alkanoyl, or (CH2)n heteroaryl; R2 and R3 are hydrogen, alkyl, alkenyl, alkynyl CN, NO2, NR 4R5, (CH2)n cycloalkyl, (CH2) n aryl, or (CH2)n heteroaryl; R2 may further be halo; n is an integer of from 0 to 5; and R4 and R5 when taken together with a nitrogen to which they are both attached complete a 3-to 8-membered ring containing carbon atoms and optionally containing O, S, or N, and substituted or unsubstituted; with the proviso that R1 and R3 are not both selected from hydrogen and C1-C6 alkyl.
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- DNA-targeted alkylating agents
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The invention relates to novel bis-benzimidazole compounds which have the ability to bind to the minor groove of DNA and to alkylate DNA, to methods of preparing the compounds, and the use of the compounds in the treatement of neoplastic disease.
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- Chloropyridylcarbonyl derivatives
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Novel chloropyridylcarbonyl derivatives of the formula STR1 in which Het is STR2 n is 1 or 2, R1 is hydrogen, optionally substituted C1-6 alkyl, optionally substituted C2-6 alkenyl, optionally substituted C3-6 alkynyl, optionally substituted phenyl or optionally substituted pyrimidinyl, and R2 and R3, independently of each other, are hydrogen or C1-4 alkyl, and acid addition salts and metal salt complexes thereof, are outstandingly active as microbicides.
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- Application of Marcus Theory to Gas-Phase SN2 Reactions: Experimental Support of the Marcus Theory Additivity Postulate
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Through the analysis of sufficiently fast identity exchange reactions, the Marcus theory additivity postulate has been tested and verified for two sets of gas-phase SN2 reactions: X- + RCH2Y -> XCH2R + Y- (where X and Y = Cl and/or Br and R = CN, C6H5).Statistical RRKM theory, within the microcanonical variational transition state (μVTS) approximation, is used to interpret the experimental kinetic data for each reaction to estimate the activation energies relative to separated reactants.Complexation energies, determined experimentally, are used in conjunction with the data from the RRKM analysis to obtain potential surface energetics.The Marcus expression is then used to determine whether the intrinsic component of the activation energy for the cross reaction is the mean of the activation energies for the two corresponding identity exchange reactions.Good agreement is found for R = C6H5 and CN.
- Wladkowski, Brian D.,Brauman, John I.
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p. 13158 - 13164
(2007/10/02)
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- Photo-Rearrangement of Polychlorobenzenes meta-Migration of Chlorine Atom
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Several polychlorobenzenes were irradiated by ultraviolet light (254 nm) in acetonitrile and the products were determined by gas chromatography.In addition to the abstraction of hydrogen atom from the solvent, photo-isomerization was shown to proceed giving isomeric polychlorobenzenes one of which chlorine atoms migrated to meta to the original position.The meta-rearrangement was rationalized by an MNDO calculation on o-chlorophenyl free radical.
- Morisaki, Kenji,Miura, Yasuki,Abe, Kazuhisa,Hirota, Minoru,Nakada, Masahiro
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p. 1589 - 1592
(2007/10/02)
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- Furanyl oximes
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Novel oxime ethers and oxime esters of the formula I given herein have various advantageous effects with regard to stimulation of plant growth, particularly in the early stage of development of the plant. Furthermore, such compounds have the property of rendering, in the sense of an antidote action, agricultural chemicals which would otherwise damage the plants (phytotoxic chemicals) more compatible with the cultivated plants. Herbicides that are insufficiently selective can be used for example in the presence of such oxime derivatives in specific cultivated crops for combating weeds, without disadvantageous consequences for the cultivated plants.
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- Absence of Isotopic Exchange Between Solid Anhydrous Iron(III) Chloride and Molecular Chlorine-36. Chlorination of Acetonitrile in the Presence of Iron(III) Chloride or the Hexakis(acetonitrile)-iron(III) Cation.
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Chlorine-36 exchange between molecular chlorine-36 and anhydrous iron(III) chloride is not observed under heterogenous conditions at room temperature, although adsorption of 36Cl2 by FeCl3 occurs.Chlorine reacts with a solution of FeCl3 in acetonitrile at room temperature to give mono- and trichloroacetonitrile and the tetrachloroferrate(III) anion as identified products.Similar behaviour is observed between Cl2 and hexakis(acetonitrile)iron(II) hexafluorophosphate in MeCN.A reaction scheme involving an iron(III)-iron(II) redox cycle is proposed to account for the (36)Cl tracer, spectroscopic, and analytical data obtained.
- Draper, Therese,Winfield, John M.,Prescott, Ann,Winterton, Neil
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p. 1584 - 1597
(2007/10/02)
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- Carbon-Halogen Bonding Studies. Halogen Redistribution Reactions between Alkyl or Acetyl Halides and Tri-n-butyltin Halides
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The equilibrium positions have been determined for the halogen redistribution reactions of tri-n-butyltin halides with a variety of structurally different types of alkyl halides and with acetyl halides.These have been related through the reaction ΔGo values to carbon-halogen bond dissociation energy differences.It is suggested that the trends observed in the latter may provide evidence for the existence of a small steric bond weakening effect in the order C-I > C-Br > C-Cl bonds on going from methyl to primary, secondary, and tertiary alkyl halides.On the other hand, with the 2,3-? bond containing allyl, benzyl, and propargyl halides , α-haloacetones, and haloacetonitriles, there may be some type of electronic carbon-halogen bond strengthening effect which lies in order C-I > C-Br > C-Cl.Finally, for the acetyl halides, the data are in agreement with increases in bond strengths resulting from ? contributions being in the order C-Cl > C-Br > C-I.
- Friedrich, Edwin C.,Abma, Charles B.
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p. 1367 - 1371
(2007/10/02)
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