6055-52-3Relevant articles and documents
Phosphine-Free Manganese Catalyst Enables Selective Transfer Hydrogenation of Nitriles to Primary and Secondary Amines Using Ammonia-Borane
Sarkar, Koushik,Das, Kuhali,Kundu, Abhishek,Adhikari, Debashis,Maji, Biplab
, p. 2786 - 2794 (2021/03/03)
Herein we report the synthesis of primary and secondary amines by nitrile hydrogenation, employing a borrowing hydrogenation strategy. A class of phosphine-free manganese(I) complexes bearing sulfur side arms catalyzed the reaction under mild reaction conditions, where ammonia-borane is used as the source of hydrogen. The synthetic protocol is chemodivergent, as the final product is either primary or secondary amine, which can be controlled by changing the catalyst structure and the polarity of the reaction medium. The significant advantage of this method is that the protocol operates without externally added base or other additives as well as obviates the use of high-pressure dihydrogen gas required for other nitrile hydrogenation reactions. Utilizing this method, a wide variety of primary and symmetric and asymmetric secondary amines were synthesized in high yields. A mechanistic study involving kinetic experiments and high-level DFT computations revealed that both outer-sphere dehydrogenation and inner-sphere hydrogenation were predominantly operative in the catalytic cycle.
Old Concepts, New Application – Additive-Free Hydrogenation of Nitriles Catalyzed by an Air Stable Alkyl Mn(I) Complex
Weber, Stefan,Veiros, Luis F.,Kirchner, Karl
supporting information, p. 5412 - 5420 (2019/11/13)
An efficient additive-free manganese-catalyzed hydrogenation of nitriles to primary amines with molecular hydrogen is described. The pre-catalyst, a well-defined bench-stable alkyl bisphosphine Mn(I) complex fac-[Mn(dpre)(CO)3(CH3)] (dpre=1,2-bis(di-n-propylphosphino)ethane), undergoes CO migratory insertion into the manganese-alkyl bond to form acyl complexes which upon hydrogenolysis yields the active coordinatively unsaturated Mn(I) hydride catalyst [Mn(dpre)(CO)2(H)]. A range of aromatic and aliphatic nitriles were efficiently and selectively converted into primary amines in good to excellent yields. The hydrogenation of nitriles proceeds at 100 °C with a catalyst loading of 2 mol % and a hydrogen pressure of 50 bar. Mechanistic insights are provided by means of DFT calculations. (Figure presented.).
Hydrosilane Reduction of Nitriles to Primary Amines by Cobalt-Isocyanide Catalysts
Sanagawa, Atsushi,Nagashima, Hideo
supporting information, p. 287 - 291 (2019/01/10)
Reduction of nitriles to silylated primary amines was achieved by combination of 1,1,3,3-tetramethyldisiloxane (TMDS) as the hydrosilane and a catalytic amount of Co(OPIV)2 (PIV = COtBu) associated with isocyanide ligands. The resulting silylated amines were subjected to acid hydrolysis or treatment with acid chlorides to give the corresponding primary amines or imides in good yields. One-pot synthesis of primary amides to primary amines with hydrosilanes was also achieved by iron-cobalt dual catalyst systems.
Liquid-phase hydrogenation of nitriles to amines facilitated by a co(ii)/zn(0) pair: a ligand-free catalytic protocol
Timelthaler, Daniel,Topf, Christoph
, p. 11604 - 11611 (2019/10/02)
The given report introduces a simple and user-friendly in situ method for the production of catalytically active cobalt particles. The approach circumvents the use of air-and moisture-sensitive reductants as well as the application of anhydrous Co-precursor salts. Accordingly, the described catalytic system is readily assembled under open-flask conditions by simply combining the components in the reaction vessel. Therefore, the arduous charging procedure of the reaction autoclave in a glovebox under an inert gas atmosphere is no longer necessary. In fact, the catalytically active material is obtained upon treatment of readily available Co(OAc)2·4 H2O with benign commercial Zn powder. The catalytic performance of the resultant material was tested in the heterogeneous hydrogenation of nitriles to the corresponding primary amines. Both activity and selectivity of the cobalt catalyst are significantly enhanced if a triflate-based Lewis acid and ammonia is added to the reaction mixture.
Non-Pincer Mn(I) Organometallics for the Selective Catalytic Hydrogenation of Nitriles to Primary Amines
Gardu?o, Jorge A.,García, Juventino J.
, p. 392 - 401 (2019/01/11)
We report herein selective catalytic hydrogenation of nitriles to primary amines with the use of the non-pincer Mn(I) compound fac-[(CO)3Mn{iPr2P(CH2)2PiPr2}(OTf)] (2) as a catalytic precursor (3 mol %) in the presence of KOtBu (10 mol %) and 2-BuOH as solvent. Benchmark benzonitrile and electron-rich aromatic and aliphatic nitriles were hydrogenated under rather mild conditions (7 bar, 90 °C, 15 min) to produce the corresponding amines in excellent to very good isolated yields (83-97%, six examples). Increasing the H2 pressure and time (35 bar, 30 min) allowed for the production of (di)amines in excellent yields (94-98%, three examples) from electron-deficient aromatic nitriles and terephthalonitrile. Notably, adiponitrile was reduced to hexamethylenediamine in 53% isolated yield. Finally, mechanistic insights were performed and suggested unsaturated Mn-hydride species performing the elementary steps during catalytic turnover.
Catalytic Reduction of Nitriles by Polymethylhydrosiloxane Using a Phenalenyl-Based Iron(III) Complex
Das, Shyamal,Das, Hari Sankar,Singh, Bhagat,Haridasan, Rahul Koottanil,Das, Arpan,Mandal, Swadhin K.
supporting information, p. 11274 - 11278 (2019/09/10)
The reduction of nitriles to primary amines using an inexpensive silane such as polymethylhydrosiloxane (PMHS) is an industrially important reaction. Herein we report the synthesis of an earth-abundant Fe(III) complex bearing a phenalenyl-based ligand that was characterized by mass spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal X-ray diffraction. The complex showed excellent catalytic activity toward reduction of aromatic, heteroaromatic, aliphatic, and sterically crowded nitriles to produce primary amines using polymethylhydrosiloxane (PMHS).
Switching the Selectivity of Cobalt-Catalyzed Hydrogenation of Nitriles
Dai, Huiguang,Guan, Hairong
, p. 9125 - 9130 (2018/09/21)
Previous studies of base metals for catalytic hydrogenation of nitriles to primary amines or secondary aldimines focus on designing complexes with elaborate structures. Herein, we report "twin" catalytic systems where the selectivity of nitrile hydrogenation can be tuned by including or omitting the ligand HN(CH2CH2PiPr2)2 (iPrPNHP). Simply treating CoBr2 with NaHBEt3 generates cobalt particles, which can catalyze the hydrogenation of nitriles to primary amines with high selectivity and broad functional group tolerance. Ligating CoBr2 with iPrPNHP followed by the addition of NaHBEt3, however, forms a homogeneous catalyst favoring secondary aldimines for both hydrogenation and hydrogenative coupling of benzonitrile.
Selective Hydrogenation of Nitriles to Primary Amines Catalyzed by a Polysilane/SiO2-Supported Palladium Catalyst under Continuous-Flow Conditions
Saito, Yuki,Ishitani, Haruro,Ueno, Masaharu,Kobayashi, Shū
, p. 211 - 215 (2017/04/21)
Hydrogenation of nitriles to primary amines with heterogeneous catalysts under liquid-phase continuous-flow conditions is described. Newly developed polysilane/SiO2-supported Pd was found to be an effective catalyst and various nitriles were converted into primary amine salts in almost quantitative yields under mild reaction conditions. Interestingly, a complex mixture was obtained under batch conditions. Lifetime experiments showed that this catalyst remained active for more than 300 h (TON≥10 000) without loss of selectivity and no metal leaching from the catalyst occurred. By using this continuous-flow hydrogenation, synthesis of venlafaxine, an antidepressant drug, has been accomplished.
Preparation method of HDI (hexamethylene diisocyanate)
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Paragraph 0024; 0025; 0028; 0029, (2017/03/25)
The invention discloses a preparation method of HDI (hexamethylene diisocyanate). The preparation method comprises steps as follows: n-hexamethylene diamine is dissolved in an organic solvent, acidic gas is introduced for salt formation, an HDI solution is obtained through a phosgenation reaction under the action of a catalyst, distillation desolvation and rectification are performed, and high-purity HDI is obtained. HDI is prepared with the salt formation method, and the defect of high probability of side reactions at the low-temperature section with a cold and hot two-step reaction method is avoided; besides, the catalyst is added, the reaction temperature is reduced, the reaction speed is increased, the phosgenation reaction is performed through gradient temperature increasing, the defects that side reactions are easily produced because of too high temperature and the reaction time is too long because of too low temperature during phosgenation with a conventional salt formation method are overcome, the production cycle is shortened, high-purity HDI can also be obtained, besides, trimethylamine is added during rectification, and the content of free chlorine in a product can be effectively reduced.
Stable and Inert Cobalt Catalysts for Highly Selective and Practical Hydrogenation of C≡N and C=O Bonds
Chen, Feng,Topf, Christoph,Radnik, J?rg,Kreyenschulte, Carsten,Lund, Henrik,Schneider, Matthias,Surkus, Annette-Enrica,He, Lin,Junge, Kathrin,Beller, Matthias
supporting information, p. 8781 - 8788 (2016/08/02)
Novel heterogeneous cobalt-based catalysts have been prepared by pyrolysis of cobalt complexes with nitrogen ligands on different inorganic supports. The activity and selectivity of the resulting materials in the hydrogenation of nitriles and carbonyl compounds is strongly influenced by the modification of the support and the nitrogen-containing ligand. The optimal catalyst system ([Co(OAc)2/Phenα-Al2O3]-800 = Cat. E) allows for efficient reduction of both aromatic and aliphatic nitriles including industrially relevant dinitriles to primary amines under mild conditions. The generality and practicability of this system is further demonstrated in the hydrogenation of diverse aliphatic, aromatic, and heterocyclic ketones as well as aldehydes, which are readily reduced to the corresponding alcohols.
