- Two-step preparation method of 6-aminocapronitrile
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The invention relates to a two-step preparation method of 6-aminocapronitrile. The two-step preparation method comprises the following steps: carrying out ammonolysis reaction on caprolactam in an inert solvent or in a molten state and hot ammonia gas to obtain 6-aminohexanamide, and dehydrating the 6-aminohexanamide in the presence of a dehydrating agent to obtain 6-aminocapronitrile. According to the invention, ring-opening ammonolysis is carried out under an anhydrous condition, so that polymerization of ammonolysis products is effectively controlled, and generation of by-products is reduced; and under the condition of no catalyst, the dehydrating agent is directly used for dehydration reaction, so that the problems of catalyst coking, short catalyst service life and the like in a catalytic dehydration process are effectively avoided.
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Paragraph 0070-0072
(2021/08/28)
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- Method for preparing 6-aminocapronitrile
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The invention provides a method for preparing 6-aminocapronitrile, which comprises the following steps: (1) respectively preheating caprolactam and ammonia gas, and introducing the preheated caprolactam and ammonia gas into a micro-channel reactor I for reaction to obtain 6-aminohexanamide; (2) carrying out gas-liquid separation on a material obtained after the reaction in the step (1) to obtain a liquid-phase material 6-aminohexanamide; and (3) preheating the 6-aminohexanamide separated in the step (2), introducing the preheated 6-aminohexanamide into a micro-channel reactor II, and simultaneously introducing a dehydrating agent to carry out a dehydration reaction, thereby obtaining the 6-aminocapronitrile. According to the method, polymerization of ammonolysis products is effectively controlled, generation of by-products is reduced, a dehydrating agent is used for a dehydration reaction under the catalyst-free condition, and the problems of catalyst coking, short catalyst service life and the like in a catalytic dehydration process are effectively avoided.
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Paragraph 0053; 0057-0058; 0059; 0063-0064; 0065; 0069; ...
(2021/10/11)
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- Method for circulating synthesis of hexamethylenediamine key intermediate
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The invention aims to provide a method for circulating synthesis of a hexamethylenediamine key intermediate, which comprises the following steps: carrying out caprolactam ammoniation reaction in two stages, and returning kettle residues generated in the process of preparing 6-aminocapronitrile from caprolactam through catalytic ammoniation to the second-stage ammoniation reaction, hydrolyzing kettle residues into caprolactam and 6aminocapronitrile at a high temperature by utilizing water generated by the first-stage ammoniation reaction and unreacted ammonia gas, and enabling the obtained caprolactam to participate in the ammoniation reaction in the reactor to generate the 6aminocapronitrile. By means of the method, resource utilization of kettle residues is achieved, the discharge amountof the kettle residues in the hexamethylenediamine production process is greatly reduced, cost reduction is facilitated, and clean production is achieved.
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Paragraph 0025-0055
(2020/12/30)
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- Facile synthesis of supported Ru-Triphos catalysts for continuous flow application in selective nitrile reduction
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The selective catalytic hydrogenation of nitriles represents an important but challenging transformation for many homogeneous and heterogeneous catalysts. Herein, we report the efficient and modular solid-phase synthesis of immobilized Triphos-type ligands in very high yields, involving only minimal work-up procedures. The corresponding supported ruthenium-Triphos catalysts are tested in the hydrogenation of various nitriles. Under mild conditions and without the requirement of additives, the tunable supported catalyst library provides selective access to both primary amines and secondary imines. Moreover, the first application of a Triphos-type catalyst in a continuous flow process is presented demonstrating high catalyst life-time over at least 195 hours without significant activity loss.
- Konrath, Robert,Heutz, Frank J.L.,Steinfeldt, Norbert,Rockstroh, Nils,Kamer, Paul C.J.
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p. 8195 - 8201
(2019/09/19)
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- Functionalized multi-walled carbon nanotubes supported Ni-based catalysts for adiponitrile selective hydrogenation to 6-aminohexanenitrile and 1,6-hexanediamine: Switching selectivity with [Bmim]OH
-
Functionalized multi-walled carbon nanotubes supported nickel-based catalysts were prepared and applied in adiponitrile (ADN) hydrogenation. The characterization results show that different functional groups such as NH2– COOH– OH– on MWCNTs surface can effectively act on metal ions by electrostatic attractions and chemical interactions so as to provide nucleation sites, and N species in MWCNTs can act as active sites for Ni deposition due to the strong electronic interactions between N species and Ni so as to promote ultra-small Ni nanoparticles formation, decrease NiO reduction activation energy, increase zero-valent Ni amounts as well as Ni nanoparticles dispersion. Furthermore, the doped N increases the lewis basicity, which favors the formation of primary amine of 6-aminohexanenitrile (ACN) and 1,6-hexanediamine (HDA). Moreover, the basic ionic liquid [Bmim]OH may switch the selectivity by inhibiting nucleophilic addition of the primary amine to the α-carbon of aldimine via the stabilization of –NH2 groups in the amino-imine intermediates so as to impede by-products formation. In addition, the mechanism for ADN hydrogenation in [Bmim]OH was studied by density functional theory calculations. Under optimized conditions, it gives 97.80% total selectivity to ACN and HDA at 95.34% ADN conversion over Ni/N-MWCNTs-800 in the presence of [Bmim]OH.
- Lv, Yang,Cui, Haishuai,Liu, Pingle,Hao, Fang,Xiong, Wei,Luo, He′an
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p. 330 - 351
(2019/03/28)
-
- Supported Ni catalyst for liquid phase hydrogenation of adiponitrile to 6-Aminocapronitrile and hexamethyenediamine
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Supported Ni catalysts prepared under different conditions, for liquid phase hydrogenation of adiponitrile (ADN) to 6-aminocapronitrile (ACN) and hexamethyenediamine (HMD), were investigated. The highly reactive imine intermediate can form condensation byproducts with primary amine products (ACN and HMD), which decreased the yield coefficient of primary amines. The catalysts support, condition of catalyst preparation and dosage of additive were studied to improve the yield. A highly dispersed Ni/SiO2 catalyst prepared by the direct reduction of Ni(NO3)2/SiO2 suppressed the condensation reactions by promoting the hydrogenation of adsorbed imines, and it gave the improved hydrogenation activity of 0.63 mol·kgcat?1·min?1 and primary amine selectivity of 94% when NaOH was added into the reactor.
- Wang, Chengqiang,Jia, Zekun,Zhen, Bin,Han, Minghan
-
-
- Improved catalytic performance of acid-activated sepiolite supported nickel and potassium bimetallic catalysts for liquid phase hydrogenation of 1,6-hexanedinitrile
-
Different inorganic acids were used to activate sepiolite, and the acid-activated sepiolites supported nickel and potassium bimetallic catalysts were prepared. Nitrogen adsorption-desorption, hydrogen chemisorption, ammonia temperature programmed desorption (NH3-TPD), temperature programmed reduction (TPR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and energy dispersive X-ray (EDX) were used to characterize the catalysts. The catalytic performance of the acid-activated sepiolite supported K-Ni bimetallic catalysts were investigated in 1,6-hexanedinitrile (HDN) hydrogenation in liquid phase. It was revealed that the potassium could increase the alkalinity of the catalyst with the aim of inhibiting the formation of the 1-azacycloheptane (ACH). And the addition of potassium reduces the particle size of nickel and improves its dispersion. Compared with hydrochloric acid and sulfuric acid, nitric acid treatment increases more silanol groups (Si[sbnd]OH) on the sepiolite surface, which is helpful to nickel particles adsorption and dispersion. Nitric acid activated sepiolite supported nickel and potassium bimetallic catalysts (K-Ni/NASEP) present the best catalytic performance, the conversion of HDN comes up to 92.0% under moderate conditions of lower temperature and pressure, the selectivity to 6-aminocapronitrile (ACN) and 1,6-hexanediamine (HDA) is up to 95.2%.
- Lv, Yang,Hao, Fang,Liu, Pingle,Xiong, Shaofeng,Luo, He'an
-
-
- Liquid phase hydrogenation of adiponitrile over directly reduced Ni/SiO2 catalyst
-
Liquid phase hydrogenation of adiponitrile (ADN) to 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) was investigated on Ni/SiO2 catalysts prepared under different conditions. In this reaction, the highly reactive imine intermediate forms condensation byproducts by reacting with the primary amine products (ACN and HMD). A highly dispersed Ni/SiO2 catalyst prepared by the direct reduction of Ni(NO3)2/SiO2 was found to suppress the condensation reactions by promoting the hydrogenation of adsorbed imine, and it gave excellent hydrogenation activity and primary amine selectivity. Addition of NaOH increased the primary amine selectivity to 79% at the ADN conversion of 86%.
- Jia, Zekun,Zhen, Bin,Han, Minghan,Wang, Chengqiang
-
-
- Catalytic properties of nickel/sepiolite promoted with potassium and lanthanum in adiponitrile hydrogenation under mild conditions
-
Ni/sepiolite, potassium and (or) lanthanum doped Ni/sepiolite catalysts were prepared by the incipient impregnation method and characterized by N2 adsorption-desorption, temperature programmed reduction (TPR), hydrogen chemisorption, powder X-ray diffraction (XRD), ammonia temperature programmed desorption (NH3-TPD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It was revealed that the potassium could inhibit the formation of the ACH by-product by neutralizing some acid sites on the catalyst, and the lanthanum could efficiently reduce the diameter and improve the dispersion of the active nickel particles. These catalysts were tested in liquid phase hydrogenation of adiponitrile (ADN). The products include 6-aminocapronitrile (ACN), hexamethylenediamine (HMDA), 1-azacycloheptane (ACH) and C12 compounds. It shows that the catalyst doped with potassium and lanthanum gives the best catalytic performance, the selectivity to ACN and HMDA reaches to 91.32% at 92.56% conversion of adiponitrile under 393 K and 2.0 MPa.
- Lv, Yang,Hao, Fang,Xiong, Shaofeng,Liu, Pingle,Luo, He'An
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p. 60933 - 60939
(2016/07/11)
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- SPIROHYDANTOIN COMPOUNDS AND THEIR USE AS SELECTIVE ANDROGEN RECEPTOR MODULATORS
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The present invention relates to a compound of formula (1-1 ) in free form or in pharmaceutically acceptable salt form in which the substituents are as defined in the specification; to its preparation, to its use as a medicament and to medicaments comprising it. The present invention further provides a combination of pharmacologically active agents and a pharmaceutical composition.
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Page/Page column 69; 70
(2013/09/12)
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- PROCESS FOR PREPARING HEXAMETHYLENEDIAMINE AND POLYAMIDES THEREFROM
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Provided herein are processes for preparing hexamethylenediamine from one or more of the cis,cis-, cis,trans- and trans,trans- double-bond isomers of muconate diester. The muconate diester can contain carbon atoms derived from biomass containing detectable 14C content determined according to ASTM D6866 and optionally containing a 14C content up to 0.0000000001%. The process converts one or more of the cis,cis-, cis,trans- and trans,trans- double-bond isomers of muconate diester to the one or more of the cis,cis-, cis,trans- and trans,trans- double-bond isomers of muconamide. The isomer(s) of muconamide is then either: 1) directly converted by reduction to hexamethylenediamine; or 2) dehydrated to one or more of the cis,cis-, cis,trans- and trans,trans- double-bond isomers of mucononitrile which is then reduced to the hexamethylenediamine; or 3) reduced to adipamide, which is dehydrated to adiponitrile, and which is converted to hexamethylenediamine. Hexamethylenediamine so prepared can be used to make various polyamides.
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-
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- An efficient hydrogenation of dinitrile to aminonitrile in supercritical carbon dioxide
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The highly selective hydrogenation of adiponitrile proceeds effectively in supercritical carbon dioxide (scCO2) to produce 6-aminocapronitrile with excellent selectivity of 100% over rhodium/alumina (Rh/Al2O 3) and without any additive, which is impossible in classical organic solvents. The presence of CO2 can be beneficial or mandatory for the exclusive formation of the aminonitrile as it can act as a solvent to enhance the activity and also as temporary protecting agent to increase the selectivity. These results successfully show the general concept of using scCO2 as a protective medium for the selectivity control of dinitrile to aminonitrile reactions. Recycling of the catalyst and further extension of this method to other dinitriles were also investigated.
- Chatterjee, Maya,Sato, Masahiro,Kawanami, Hajime,Yokoyama, Toshirou,Suzuki, Toshishige,Ishizaka, Takayuki
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scheme or table
p. 2394 - 2398
(2011/02/22)
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- PROCESS FOR HYDROGENATING NITRILES TO PRIMARY AMINES OR AMINONITRILES AND CATALYSTS SUITABLE THEREFOR
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The invention relates to a process for hydrogenating oligonitriles which have at least two nitrile groups in the presence of a catalyst which, before commencement of the hydrogenation, is pretreated by contacting with a compound A which is selected from alkali metal carbonates, alkaline earth metal carbonates, ammonium carbonate, alkali metal hydrogencarbonates, alkaline earth metal hydrogencarbonates, ammonium hydrogencarbonate, alkaline earth metal oxocarbonates, alkali metal carboxylates, alkaline earth metal carboxylates, ammonium carboxylates, alkali metal dihydrogenphosphates, alkaline earth metal dihydrogenphosphates, alkali metal hydrogenphosphates, alkaline earth metal hydrogenphosphates, alkali metal phosphates, alkaline earth metal phosphates and ammonium phosphate, alkali metal acetates, alkaline earth metal acetates, ammonium acetate, alkali metal formiates, alkaline earth metal formiates, ammonium formiate, alkali metal oxalates, alkaline earth metal oxalates and ammonium oxalate.
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Page/Page column 5
(2009/04/24)
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- Process for Hydrogenating Nitriles to Primary Amines or Aminonitriles and Catalysts Suitable Therefor
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A process for hydrogenating oligonitriles which have at least two nitrile groups in the presence of a catalyst which, before commencement of the hydrogenation, is pretreated by contacting with a compound A which is selected from alkali metal carbonates, alkaline earth metal carbonates, ammonium carbonate, alkali metal hydrogencarbonates, alkaline earth metal hydrogencarbonates, ammonium hydrogencarbonate, alkaline earth metal oxocarbonates, alkali metal carboxylates, alkaline earth metal carboxylates, ammonium carboxylates, alkali metal dihydrogen phosphates, alkaline earth metal dihydrogen phosphates, alkali metal hydrogen phosphates, alkaline earth metal hydrogen phosphates, alkali metal phosphates, alkaline earth metal phosphates and ammonium phosphate, alkali metal acetates, alkaline earth metal acetates, ammonium acetate, alkali metal formates, alkaline earth metal formates, ammonium formate, alkali metal oxalates, alkaline earth metal oxalates and ammonium oxalate.
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Page/Page column 5
(2009/01/20)
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- Poly(diiododiacetylene): Preparation, isolation, and full characterization of a very simple poly(diacetylene)
-
Poly(diiodiacetylene), or PIDA, is a conjugated polymer containing the poly(diacetylene) (PDA) backbone but with only iodine atom substituents. The monomer diiodobutadiyne (1) can be aligned in the solid state with bis(nitrile) oxalamide hosts by hydrogen bonds between oxalamide groups and weak Lewis acid-base interactions (halogen bonds) between nitriles and iodoalkynes. The resulting cocrystals start out pale blue but turn shiny and copper-colored as the polymerization progresses. The development of a crystallization methodology that greatly improves the yield of PIDA to about 50% now allows the full characterization of the polymer by X-ray diffraction, solid-state 13C MAS NMR, Raman, and electron absorption spectroscopy. Comparison of a series of hosts reveals an odd-even effect in the topochemical polymerization, based on the alkyl chain length of the host. In the cocrystals formed with bis(pentanenitrile) oxalamide (4) and bis(heptanenitrile) oxalamide (6), the host/guest ratio is 1:2 and the monomer polymerizes spontaneously at room temperature, while in the case of bis(butanenitrile) oxalamide (3) and bis(hexanenitrile) oxalamide (5), where the host and guest form cocrystals in a 1:1 ratio, the polymerization is disfavored and does not go to completion. The topochemical polymerization can also be observed in water suspensions of micrometer-sized 6.1 cocrystals; the size distribution of these microcrystals, and the resulting polymer chains, can be controlled by sonication. Completely polymerized PIDA cocrystals show a highly resolved vibronic progression in their UV/vis absorption spectra. Extensive rinsing of the crystals in organic solvents such as methanol, THF, and chloroform separates the polymer from the soluble host. Once isolated, PIDA forms blue suspensions in a variety of solvents. The UV/vis absorption spectra of these suspensions match the cocrystal spectrum, without the vibronic resolution. However, they also include a new longer-wavelength absorption peak, associated with aggregation of the polymer chains.
- Luo, Liang,Wilhelm, Christopher,Sun, Aiwu,Grey, Clare P.,Lauher, Joseph W.,Goroff, Nancy S.
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p. 7702 - 7709
(2008/12/22)
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- Separation of 6-aminocapronitrile and hexamethylenediamine from a mixture comprising hexamethylenediamine, 6-aminocapronitrile and tetrahydroazepine
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The invention relates to the field of separation by distillation of 6-aminocapronitrile (ACN) and hexamethylenediamine (HMD) from a mixture comprising ACN, HMD, tetrahydrozaepine (THA), adiponitrile (ADN) and low boilers (LB). A method for producing a distillate stream comprising HMD is disclosed, which is suitable for the production of Nylon-6,6. The tails stream from the distillation of the mixture can be further distilled to produce a distillate comprising ACN and THA, which is particularly suitable for use in the production of caprolactam and Nylon-6 from the caprolactam. Process conditions of the method of the invention disfavor the production of 2-cyanocyclopentylideneirnine (CPI).
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Page/Page column 2-3
(2008/06/13)
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- Use of modifiers in a dinitrile hydrogenation process
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Catalytic process for hydrogenating a dinitrile to produce both aminocapronitrile and hexamethylenediamine in which the dinitrile is contacted with hydrogen in the presence of a catalyst and a modifier selected from the group consisting of quaternary ammonium hydroxides, cyanides, fluorides and thiocyanides; quaternary phosphonium hydroxide; carbon monoxide; and hydrogen cyanide.
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Page/Page column 3
(2008/06/13)
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- NITRILE HYDROGENATION ON HETEROGENEOUS CATALYSTS IN THE PRESENCE OF IONIC LIQUIDS
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Disclosed is a method for hydrogenating nitrile functions contained in organic compounds on at least one heterogeneous catalyst, hydrogenation taking place in the presence of an ionic liquid.
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Page/Page column 25
(2008/06/13)
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- Process for producing hexamethylenediamine and aminocapronitrile from adiponitrile, wherein the hexamethylenediamine contains less than 100 ppm tetrahydroazepine
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Process for making both ACN and HMD from partial hydrogenation of ADN by using a combination of distillations resulting in the formation of a mixture of HMD and THA that can be hydrogenated to produce a mixture of HMD and HMI that can be separated easily by simple distillation.
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Page/Page column 2
(2008/06/13)
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- Process for producing caprolactam
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A process for preparing caprolactam by reacting 6-aminocapronitrile with water in the presence of catalysts comprises using a starting mixture of 6-aminocapronitrile and the tetrahydroazepine derivative of the formula and conducting the reaction in liquid phase in the presence of a heterogeneous catalyst. Also describes a process for preparing said tetrahydroazepine derivative I and its use for preparing caprolactam and polycaprolactam.
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Page column 5
(2008/06/13)
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- Method for removing 6-aminocapronitrile from mixtures that contain 6-aminocapronitrile, adipodinitrile and hexamethylenediamine
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The invention relates to a method for removing, by distillation, 6-aminocapronitrile from mixtures that contain 6-aminocapronitrile, adipodinitrile and hexamethylenediamine, by a) removing the hexamethylenediamine from the mixture while obtaining a mixture (I) that has a hexamethylenediamine content of less than 1 wt.-%, b) removing completely or partially the 6-aminocapronitrile from mixture (I) while obtaining a mixture (II) whose content in substances that have a higher boiling point as 6-aminocapronitrile under distillation conditions and that cannot be formed by dimerization reactions when 6-aminocapronitrile is thermally treated is less than 1 wt.-%, and c) completely or partially removing from mixture (II) the hexamethylenediamine that might be present while obtaining a mixture (IV) whose hexamethylenediamine content is higher than that of mixture (II), and a mixture (V) whose hexamethylenediamine content is lower than that of mixture (II). A process is provided for tire distillative separation of 6-aminocapronitrile from mixtures containing 6-aminocapronitrile, adipodinitrile and hexamethylenediamine, wherein a) the hexamethylenediamine is separated from the mixture to give a mixture (I) with a hexamethylenediamine content of less than 1% by weight; b) all or part of the 6-aminocapronitrile is separated from the mixture (I) to give a mixture (II) whose content of substances which boil above 6-aminocapronitrile under distillation conditions and cannot be formed by dimerization reactions of 6-aminocapronitrile under thermal stress is less than 1% by weight; and c) all or part of the hexamethylenediamine present is separated from the mixture (II) to give a mixture (IV) whose hexamethylenediamine content is higher than that of the mixture (II), and a mixture (V) whose hexamethylenediamine content is lower than that of the mixture (II).
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-
- Method for purifying lactams
-
The invention concerns a method for purifying lactams, more particularly lactams obtained by cyclizing hydrolysis of aminonitrile. More particularly, the invention concerns the purification of ε-caprolactam obtained by cyclizing hydrolysis of aminocapronitrile which consists in eliminating the ammonia from the reaction medium of the hydrolysis then in recuperating the lactam from said medium in purified form. Said recuperation is carried out by performing at least a distillation of the lactam in the presence of a base producing optionally a fronts fraction comprising compounds more volatile than the lactam, a fraction comprising the lactam to be recuperated to the degree of desired purity and a distillation tails comprising the lactam and compounds less volatile than the lactam. The distillation tails are treated by various processes such as evaporation in thin layers to recuperate the major part of the comprised caprolactam and recycling the latter in the purification process. The invention enables a high rate of recuperation of the caprolactam contained in the hydrolysis medium, while observing the required criteria of purity.
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-
- Method for the hemihydrogenation of dinitriles in order to form aminonitriles
-
The present invention relates to the hemihydrogenation of dinitriles to corresponding aminonitriles. It relates more particularly to the use of a catalyst based on Raney nickel with rhodium and/or iridium.
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-
- Method for hemihydrogenating dinitriles to form aminonitriles
-
A process is provided for the hemihydrogenation of dinitriles to corresponding aminonitriles using hydrogen in the presence of a supported catalyst. The supported catalyst comprises ruthenium supported on a carbon black, called acetylene black, resulting from the pyrolysis of paraffin oils.
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Page/Page column 5
(2008/06/13)
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- Method for simultaneous production of 6-aminocapronitrile and hexamethylenediamine
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A process for the coproduction of 6-aminocapronitrile and hexamethylenediamine starting from adiponitrile bya) hydrogenating adiponitrile in the presence of a catalyst comprising an element of the eighth transition group as catalytically active component, to obtain a mixture comprising 6-aminocapronitrile, hexamethylenediamine, adiponitrile and high boilers,b) distillatively removing hexamethylenediamine from the mixture comprising 6-aminocapronitrile, hexamethylenediamine, adiponitrile and high boilers, and eitherc1) distillatively removing 6-aminocapronitrile, and thend1) distillatively removing adiponitrile, orc2) simultaneously distillatively removing 6-aminocapronitrile and adiponitrile into separate fractions is characterized by base of column temperatures below 185° C. in steps d1) or c2).
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Page column 7
(2008/06/13)
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- Method for preparing aminonitrile and diamine
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The present invention relates to a process for the preparation of aminonitrile and of diamine by catalytic hydrogenation of dinitrile. It consists of a process for the preparation of aminonitrile and of diamine by catalytic hydrogenation of aliphatic dinitrile having from 3 to 12 carbon atoms, characterized in that the final reaction mixture, the catalyst of which has been separated beforehand, is acidified by addition of a sufficient amount of an inorganic or organic acid, before being subjected to an operation of distillation of the products of the reaction and of the unconverted dinitrile. It relates more particularly to the preparation of 6-aminocapronitrile and of hexamethylenediamine by hydrogenation of adiponitrile. The 6-aminocapronitrile can be hydrolysed in the liquid phase or in the gas phase to result in caprolactam. The hexamethylenediamine can be used very particularly to prepare polyamide-6,6 by reaction with adipic acid.
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Page column 4
(2008/06/13)
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- Method for producing hexamethylene diamine
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A process for catalytic hydrogenation of adiponitrile to hexamethylenediamine at elevated temperature and elevated pressure in the presence of catalysts based on elemental iron as catalytically active component and ammonia as solvent comprisesa) hydrogenating adiponitrile at from 70 to 220° C. and from 100 to 400 bar in the presence of catalysts based on elemental iron as catalytically active component and ammonia as solvent to obtain a mixture comprising adiponitrile,6-aminocapronitrile, hexamethylenediamine and high boilers until the sum total of the 6-aminocapronitrile concentration and the adiponitrile concentration is within the range from 1 to 50% by weight, based on the ammonia-free hydrogenation mixture,b) removing ammonia from the hydrogenation effluent,c) removing hexamethylenediamine from the remaining mixture,d) separating 6-aminocapronitrile and adiponitrile from high boilers individually or together, ande) returning 6-aminocapronitrile, adiponitrile or mixtures thereof into step a).
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Page column 6
(2008/06/13)
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- Nickel-magnesia catalysts: An alternative for the hydrogenation of 1,6-hexanedinitrile
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Two Ni-MgO systems were synthesized and characterized as Ni catalysts for the hydrogenation of 1,6-hexanedinitrile (adiponitrile) in the gas phase. All three catalysts displayed high selectivity to 1,6-hexanediamine, for a total conversion with a maximum
- Salagre,Medina,Serra,Sueiras,Cesteros
-
p. 202 - 209
(2007/10/03)
-
- Selective half-hydrogenation of adiponitrile to aminocapronitrile on Ni-based catalysts elaborated from lamellar double hydroxide precursors
-
Layered double hydroxides with a hydrotalcite-like structure and containing Ni2+/Mg2+/Al3+ cations in different amounts were prepared and activated under various conditions. These catalysts were tested in the liquid-phase hydrogenation of adiponitrile with the aim of producing aminocapronitrile (ACN). The reaction was carried out in a batch reactor at 323-353 K and 2.5 MPa H2 pressure with catalysts reduced at 823 K. The products were ACN, hexamethylenediamine (HMDA), azacycloheptane (ACH), and C12 compounds. The ACH and C12 byproducts are formed by condensation between "imine-" and "amine-like" adsorbed species on metal and acid sites (bifunctional mechanism), and on the metal sites as well. The tuned addition of Mg (Mg/(Mg + Ni)=0.20) allows us to reach the highest selectivity and yield in ACN (66% selectivity at 70% conversion, 50% yield at 85% conversion). The IR spectroscopy of adsorbed CO provided evidence of the presence of smaller Ni0 ensembles on the sample with Mg/(Mg + Ni)=0.20, as well as larger back-donation from Ni0 sites to the 2π* orbitals of CO. On that account, it is proposed that the lower formation of HMDA, ACH, and C12 byproducts may be mainly due to (i) a faster desorption of ACN from the Ni0 surface before deeper hydrogenation and (ii) the decrease of transimination reactions which need large Ni0 ensembles to proceed. The correlation between acidity and condensation reactions is not obvious, since upon Mg substitution for Ni, the number of acid sites increases but their strength decreases concurrently, as shown by temperature-programmed desorption of NH3.
- Tichit, Didier,Durand, Robert,Rolland, Alice,Coq, Bernard,Lopez, Joseph,Marion, Philippe
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p. 511 - 520
(2007/10/03)
-
- Gas-phase adiponitrile hydrogenation over modified Ni-P/SiO2 amorphous catalysts
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Gas-phase hydrogenation of adiponitrile was carried out in a fixed-bed reactor at 1 atm pressure, and in the absence of ammonia. In comparison with other Ni-based catalysts, the Ni-P/SiO2 amorphous catalyst exhibited higher activity and/or better selectivity to 1,6-hexanediamine, which could be further improved by W or MgO-additives.
- Li, Hexing,Wang, Minghui,Xu, Yeping
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p. 1048 - 1049
(2007/10/03)
-
- Surface Characterization and Hydrogenation Properties of Several Nickel/α-Alumina Catalysts
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Studies of the chemical preparation, X-ray photoelectron spectra (XPS), activation energies of reduction, temperature-programmed reduction (TPR), X-ray diffraction (XRD) and catalytic activities of several nickel/α-alumina catalysts have been caried out for the catalytic hydrogenation of hexanedinitrile, in a continuous process at 1 atm pressure, 443 K, and in the absence of ammonia.XPS results show complete reduction of non-stoichiometric NiO on α-alumina at temperatures higher than 623 K and higher surface nickel dispersion with increasing nickel content anddecreasing reduction temperatures.Activation energies of reduction for the α-alumina-supported non-stoichiometric NIO were higher than those of the unsupported non-stoichiometric NiO.TPR results show that the initial and final temperatures of reduction of the α-alumina-supported nonstoichiometric NiO are higher with unsupported NiO, confirming the inhibiting effect of α-alumina on NiO reduction.XRD measurements show the presence of α-alumina, NiO and Ni phases, and also the increase in crystallite size with increasing reduction temperature.Catalytic conversions increase with the nickel content and selectivities toward 6-aminohexanenitrile increase at lower nickel contents, high space velocities, and higher metallic sintering, probably owing to the presence of a higher content of specific crystal sites responsible for the production of 6-aminohexanenitrile.A mechanism is proposed.
- Medina, Francisco,Salagre, Pilar,Sueiras, Jesus-Eduardo,Fierro, Jose-Luis-Garcia
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p. 3507 - 3512
(2007/10/02)
-
- β-TRIMETHYLSILYLETHANESULFONYL CHLORIDE (SES-Cl): A NEW REAGENT FOR PROTECTION OF AMINES
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The title compound, easily prepared in two steps from vinyltrimethylsilane, is a useful reagent for the protection of primary and secondary amines as their sulfonamides, which are cleaved by fluoride ion.
- Weinreb, Steven M.,Demko, Donald M.,Lessen, Thomas A.,Demers, James P.
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p. 2099 - 2102
(2007/10/02)
-