1897-52-5Relevant articles and documents
Preparation method of 2,6-difluorobenzamide
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Paragraph 0074-0079; 0082-0085; 0086-0090; 0091-0094; 0095, (2021/05/29)
The invention provides a preparation method of 2,6-difluorobenzamide with hydrogen fluoride as a reaction raw material, wherein the method improves the atom utilization rate of the reaction, can produce a byproduct acid, effectively reduces the production cost of the product, and improves the market competitiveness of the product; besides, the whole process does not generate mixed waste salt, and the process flow is simple.
Method for dehydrating primary amide into nitriles under catalysis of cobalt
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Paragraph 0114-0116, (2021/06/21)
The invention provides a method for dehydrating primary amide into nitrile. The method comprises the following steps: mixing primary amide (II), silane, sodium triethylborohydride, aminopyridine imine tridentate nitrogen ligand cobalt complex (I) and a reaction solvent under the protection of inert gas, carrying out reacting at 60-100 DEG C for 6-24 hours, and post-treating reaction liquid to obtain a nitrile compound (III). According to the invention, an effective method for preparing nitrile compounds by cobalt-catalyzed primary amide dehydration reaction by using the novel aminopyridine imine tridentate nitrogen ligand cobalt complex catalyst is provided; and compared with existing methods, the method has the advantages of simple operation, mild reaction conditions, wide application range of reaction substrates, high selectivity, stable catalyst, high efficiency, and relatively high practical application value in synthesis.
Synthesis and Characterization of Bidentate (P^N)Gold(III) Fluoride Complexes: Reactivity Platforms for Reductive Elimination Studies
Genoux, Alexandre,Biedrzycki, Micha?,Merino, Estíbaliz,Rivera-Chao, Eva,Linden, Anthony,Nevado, Cristina
supporting information, p. 4164 - 4168 (2020/12/23)
A new family of cationic, bidentate (P^N)gold(III) fluoride complexes has been prepared and a detailed characterization of the gold-fluoride bond has been carried out. Our results correlate with the observed reactivity of the fluoro ligand, which undergoes facile exchange with both cyano and acetylene nucleophiles. The resulting (P^N)arylgold(III)C(sp) complexes have enabled the first study of reductive elimination on (P^N)gold(III) systems, which demonstrated that C(sp2)?C(sp) bond formation occurs at higher rates than those reported for analogous phosphine-based monodentate systems.
Synthesis method of insecticide teflubenzuron and intermediate 2,6-difluorobenzamide of insecticide teflubenzuron
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Paragraph 0056; 0059; 0064; 0067; 0072; 0075, (2020/12/10)
The invention discloses a synthesis method of an insecticide teflubenzuron and an intermediate 2,6-difluorobenzamide of the insecticide teflubenzuron, belonging to the field of pesticides. The synthesis method comprises the following steps: step 1, preparation of 2,6-dichlorobenzylidene chloride: preparing turbid liquid of dichlorotoluene and phosphorus pentachloride, introducing chlorine gas, layering materials by utilizing a gas-liquid separator, collecting a crude product, and rectifying the crude product to obtain the 2,6-dichlorobenzylidene chloride; and 2, preparation of 2,6-dichlorobenzonitrile: mixing 2,6-dichlorobenzylidene chloride, acetic acid, zinc chloride, hydroxylamine hydrochloride and sodium acetate, carrying out heating for a reflux reaction, conducting cooling, stirring,filtering and drying successively after the reaction is completed so as to obtain 2, 6-dichlorobenzonitrile. By adopting a one-pot method, a reaction route is shortened, total yield is increased to 67.3% from conventional 55.4%, and cost is greatly reduced.
An Air-Stable N-Heterocyclic [PSiP] Pincer Iron Hydride and an Analogous Nitrogen Iron Hydride: Synthesis and Catalytic Dehydration of Primary Amides to Nitriles
Fenske, Dieter,Fuhr, Olaf,Li, Xiaoyan,Sun, Hongjian,Wang, Yajie,Xie, Shangqing,Zhang, Hua
, (2020/03/13)
An air-stable N-heterocyclic PSiP pincer iron hydride FeH(PMe3)2(SiPh(NCH2PPh2)2C6H4) (4) was synthesized by Si-H activation of a Ph-substituted [PSiP] pincer ligand. The analogous strong electron-donating iPr-substituted [PSiP] pincer ligand was prepared and introduced into iron complex to give an iron nitrogen complex FeH(N2)(PMe3)(SiPh(NCH2PiPr2)2C6H4) (6). Both 4 and 6 showed similar high efficiency for catalytic dehydration of primary amides to nitriles. Air-stable iron hydride 4 was the best catalyst for its stabilization and convenient preparation. A diverse range of cyano compounds including aromatic and aliphatic species was obtained in moderate to excellent yields. A plausible catalytic reaction mechanism was proposed.
Lewis acid promoted dehydration of amides to nitriles catalyzed by [PSiP]-pincer iron hydrides
Chang, Guoliang,Li, Xiaoyan,Zhang, Peng,Yang, Wenjing,Li, Kai,Wang, Yajie,Sun, Hongjian,Fuhr, Olaf,Fenske, Dieter
, (2020/01/21)
The dehydration of primary amides to their corresponding nitriles using four [PSiP]-pincer hydrido iron complexes 1–4 [(2-Ph2PC6H4)2MeSiFe(H)(PMe3)2 (1), (2-Ph2PC6H4)2HSiFe(H)(PMe3)2 (2), (2-(iPr)2PC6H4)2HSiFe(H)(PMe3)2 (3) and (2-(iPr)2PC6H4)2MeSiFe(H)(PMe3)2 (4)] as catalysts in the presence of (EtO)3SiH as dehydrating reagent was explored in the good to excellent yields. It was proved for the first time that Lewis acid could significantly promote this catalytic system under milder reaction conditions than other Lewis acid-promoted system, such as shorter reaction time or lower reaction temperature. This is also the first example that dehydration of primary amides to nitriles was catalyzed by silyl hydrido iron complexes bearing [PSiP]-pincer ligands with Lewis acid as additive. This catalytic system has good tolerance for many substituents. Among the four iron hydrides 1 is the best catalyst. The effects of substituents of the [PSiP]-pincer ligands on the catalytic activity of the iron hydrides were discussed. A catalytic reaction mechanism was proposed. Complex 4 is a new iron complex and was fully characterized. The molecular structure of 4 was determined by single crystal X-ray diffraction.
NHC-catalyzed silylative dehydration of primary amides to nitriles at room temperature
Ahmed, Jasimuddin,Hota, Pradip Kumar,Maji, Subir,Mandal, Swadhin K.,Rajendran, N. M.
supporting information, p. 575 - 578 (2020/01/29)
Herein we report an abnormal N-heterocyclic carbene catalyzed dehydration of primary amides in the presence of a silane. This process bypasses the energy demanding 1,2-siloxane elimination step usually required for metal/silane catalyzed reactions. A detailed mechanistic cycle of this process has been proposed based on experimental evidence along with computational study.
Mechanistic Insights into C(sp2)?C(sp)N Reductive Elimination from Gold(III) Cyanide Complexes
Genoux, Alexandre,González, Jorge A.,Merino, Estíbaliz,Nevado, Cristina
supporting information, p. 17881 - 17886 (2020/08/19)
A new family of phosphine-ligated dicyanoarylgold(III) complexes has been prepared and their reactivity towards reductive elimination has been studied in detail. Both, a highly positive entropy of activation and a primary 12/13C KIE suggest a late concerted transition state while Hammett analysis and DFT calculations indicate that the process is asynchronous. As a result, a distinct mechanism involving an asynchronous concerted reductive elimination for the overall C(sp2)?C(sp)N bond forming reaction is characterized herein, for the first time, complementing previous studies reported for C(sp3)?C(sp3), C(sp2)?C(sp2), and C(sp3)?C(sp2) bond formation processes taking place on gold(III) species.
Efficient dehydration of primary amides to nitriles catalyzed by phosphorus-chalcogen chelated iron hydrides
Li, Kai,Sun, Hongjian,Yang, Wenjing,Wang, Yajie,Xie, Shangqing,Li, Xiaoyan,Fuhr, Olaf,Fenske, Dieter
, (2020/01/22)
A series of phosphorus-chalcogen chelated hydrido iron (II) complexes 1–7, (o-(R'2P)-p-R-C6H4Y)FeH (PMe3)3 (1: R = H, R' = Ph, Y = O; 2: R = Me, R' = Ph, Y = O; 3: R = H, R' = iPr, Y = O; 4: R = Me, R' = iPr, Y = O; 5: R = H, R' = Ph, Y = S; 6: R = Me, R' = Ph, Y = S; 7: R = H, R' = Ph, Y = Se), were synthesized. The catalytic performances of 1–7 for dehydration of amides to nitriles were explored by comparing three factors: (1) different chalcogen coordination atoms Y; (2) R' group of the phosphine moiety; (3) R substituent group at the phenyl ring. It is confirmed that 5 with S as coordination atom has the best catalytic activity and 7 with Se as coordination atom has the poorest catalytic activity among complexes 1, 5 and 7. Electron-rich complex 4 is the best catalyst among the seven complexes and the dehydration reaction was completed by using 2 mol% catalyst loading at 60 °C with 24 hr in the presence of (EtO)3SiH in THF. Catalyst 4 has good tolerance to many functional groups. Among the seven iron complexes, new complexes 3 and 4 were obtained via the O-H bond activation of the preligands o-iPr2P(C6H4)OH and o-iPr2P-p-Me-(C6H4)OH by Fe(PMe3)4. Both 3 and 4 were characterized by spectroscopic methods and X-ray diffraction analysis. The catalytic mechanism was experimentally studied and also proposed.
Palladium-Catalyzed Cyanation under Mild Conditions: A Case Study to Discover Appropriate Substrates among Halides and Pseudohalides
Rajendra, Merla Arjuna,Sunil,Sajith, Ayyiliath Meleveetil,Joy, Muthipeedika Nibin,Bakulev, Vasiliy A.,Haridas, Karickal Raman
supporting information, p. 1629 - 1633 (2020/09/15)
A case study has been effectively carried out to identify a suitable substrate among halides and pseudohalides for the palladium-catalyzed cyanation reactions under mild conditions. Among the various substrates considered for evaluation, aryl pentafluorobenzenesulfonates and nonaflates were identified to be the best substrates when compared to corresponding halides and pseudohalides. The substoichiometric use of nontoxic, environmentally benign potassium hexacyanoferrate as a cyanide source and exceptionally milder conditions further highlights the significance of the protocol developed. A wide range of electronically biased and sterically challenging substrates provided the corresponding the nitriles in good to excellent yields.
