1821-39-2Relevant academic research and scientific papers
Synthesis of new sterically hindered anilines
Steele, Barry R.,Georgakopoulos, Spyros,Micha-Screttas, Maria,Screttas, Constantinos G.
, p. 3091 - 3094 (2007)
Ring-alkylated primary, secondary and tertiary anilines have been ethylated with ethylene at benzylic positions in a simple and inexpensive one-pot procedure which is mediated by the use of the superbase system nBuLi/LiK(OCH2CH2NMe2)2 in the presence of Mg(OCH2CH2OEt)2. Primary and secondary anilines are ethylated readily at ortho-benzylic positions but with difficulty or not at all at other positions. Tertiary anilines are ethylated at all positions. Mono- or diethylation occurs depending on the steric constraints present. Wiley-VCH Verlag GmbH & Co. KGaA, 2007.
Effect of Zr on catalytic performance of unsupported Ni(Zr)Mo and Ni(Zr)W sulfide catalysts for quinoline hydrodenitrogenation
Jiang, Zongxuan,Li, Can,Liu, Tiefeng,Liu, Xinyi,Zhang, Cen
, (2020/08/19)
To increase the dispersion of active species and full utilization of active metals are of great importance for hydrodenitrogenation (HDN) performance of unsupported hydrotreating catalysts. Herein, a series of unsupported Ni(Zr)MoS and Ni(Zr)WS catalysts were prepared from Ni(Zr) layered double hydroxide (LDH) precursors. The Zr species remarkably promote the dispersion and reducibility of NiMo and NiW composite species. Also, the total HDN rate constants are increased from 2.42 h?1 to 9.18 h?1 for Ni(Zr)MoS and from 5.68 h?1 to 23.0 h?1 for Ni(Zr)WS, and exhibit a maximum at a Zr/Ni atomic ratio of about 0.04. The HDN selectivities indicate that the Zr species increase the number of superficial active sites without affecting their structure. The present work shows that the crystallinity of LDH precursors is crucial to the structure of unsupported sulfide catalysts, and a suitable amount of Zr could be a dispersive promoter to increase the HDN activity.
Selective Synthesis of Primary Anilines from NH3 and Cyclohexanones by Utilizing Preferential Adsorption of Styrene on the Pd Nanoparticle Surface
Koizumi, Yu,Jin, Xiongjie,Yatabe, Takafumi,Miyazaki, Ray,Hasegawa, Jun-ya,Nozaki, Kyoko,Mizuno, Noritaka,Yamaguchi, Kazuya
supporting information, p. 10893 - 10897 (2019/07/12)
Dehydrogenative aromatization is one of the attractive alternative methods for directly synthesizing primary anilines from NH3 and cyclohexanones. However, the selective synthesis of primary anilines is quite difficult because the desired primary aniline products and the cyclohexanone substrates readily undergo condensation affording the corresponding imines (i.e., N-cyclohexylidene-anilines), followed by hydrogenation to produce N-cyclohexylanilines as the major products. In this study, primary anilines were selectively synthesized in the presence of supported Pd nanoparticle catalysts (e.g., Pd/HAP, HAP=hydroxyapatite, Ca10(PO4)6(OH)2) by utilizing competitive adsorption unique to heterogeneous catalysis; in other words, when styrene was used as a hydrogen acceptor, which preferentially adsorbs on the Pd nanoparticle surface in the presence of N-cyclohexylidene-anilines, various structurally diverse primary anilines were selectively synthesized from readily accessible NH3 and cyclohexanones. The Pd/HAP catalyst was reused several times though its catalytic performance gradually declined.
Simultaneous hydrodenitrogenation and hydrodesulfurization on unsupported Ni-Mo-W sulfides
Albersberger, Sylvia,Hein, Jennifer,Schreiber, Moritz W.,Guerra, Santiago,Han, Jinyi,Gutiérrez, Oliver Y.,Lercher, Johannes A.
, p. 344 - 355 (2017/09/30)
The catalytic properties of unsupported Ni-Mo-W sulfides (composites of Ni-Mo(W)S2 mixed sulfides and Ni3S2) obtained from precursors synthesized via co-precipitation, hydrothermal, and thiosalt decomposition were explored
Selective synthesis of primary anilines from cyclohexanone oximes by the concerted catalysis of a Mg-Al layered double hydroxide supported Pd catalyst
Jin, Xiongjie,Koizumi, Yu,Yamaguchi, Kazuya,Nozaki, Kyoko,Mizuno, Noritaka
, p. 13821 - 13829 (2017/11/06)
Although the selective conversion of cyclohexanone oximes to primary anilines would be a good complement to the classical synthetic methods for primary anilines, which utilize arenes as the starting materials, there have been no general and efficient methods for the conversion of cyclohexanone oximes to primary anilines until now. In this study, we have successfully realized the efficient conversion of cyclohexanone oximes to primary anilines by utilizing a Mg-Al layered double hydroxide supported Pd catalyst (Pd(OH)x/LDH) under ligand-, additive-, and hydrogen-acceptor-free conditions. The substrate scope was very broad with respect to both cyclohexanone oximes and cyclohexenone oximes, which gave the corresponding primary anilines in high yields with high selectivities (17 examples, 75% to >99% yields). The reaction could be scaled up (gram-scale) with a reduced amount of the catalyst (0.2 mol %). Furthermore, the one-pot synthesis of primary anilines directly from cyclohexanones and hydroxylamine was also successful (five examples, 66-99% yields). The catalysis was intrinsically heterogeneous, and the catalyst could be reused for the conversion of cyclohexanone oxime to aniline at least five times with keeping its high catalytic performance. Kinetic studies and several control experiments showed that the high activity and selectivity of the present catalyst system were attributed to the concerted catalysis of the basic LDH support and the active Pd species on LDH. The present transformation of cyclohexanone oximes to primary anilines proceeds through a dehydration/dehydrogenation sequence, and herein the plausible reaction mechanism is proposed on the basis of several pieces of experimental evidence.
Heterogeneous catalytic synthesis of quinoline compounds from aniline and C1-C4 alcohols over zeolite-based catalysts
Huang, Chen,Li, An,Chao, Zi-Sheng
, p. 48275 - 48285 (2017/10/31)
The synthesis of quinolines from aniline and a C1-C4 alcohol was conducted under gas-phase reaction conditions over a series of zeolite-based catalysts. The texture and acid properties of catalysts were characterized by XRD, FT-IR, BET and NH3-TPD techniques. It was found that the total yield of quinolines was positively related to the relative content of Lewis acid sites of the catalyst. Among others, the ZnCl2/Ni-USY-acid catalyst possessed the best performance. Over this catalyst, the reactions of aniline and most of the alcohols provided a 42.3-79.7% total yield of quinolones under mild conditions, however, those of aniline and methanol, ethanol and iso-propanol predominantly led to N-alkylanilines. Furthermore, the reaction pathways for synthesizing quinolines via aniline reacting with polyhydric alcohols or monohydric alcohols was proposed in our work.
Preparation and characterization of NiW supported on Al-modified MCM-48 catalyst and its high hydrodenitrogenation activity and stability
Shao, Mingqiang,Cui, Haitao,Guo, Shaoqing,Zhao, Liangfu,Tan, Yisheng
, p. 61747 - 61757 (2016/07/11)
Al-containing MCM-48 with different Si/Al ratios and aluminum free MCM-48 materials were successfully prepared with hexadecyl trimethyl ammonium bromide (CTAB) and poly(ethylene oxide) poly(propylene oxide)-poly(ethylene oxide) triblock copolymer (P123) as a co-template. A series of characterizations show that both the supports and the NiW supported catalysts are highly ordered. The acid strength of the supports is enhanced when Al is introduced and when its content is increased. The acid amount and strength is further improved by supporting the NiW species. The oxide precursors show a high degree of sulfidation under mild sulfidation conditions. The activity of the Al-modified catalysts for quinoline hydrodenitrogenation (HDN) is much higher than that of aluminum free NiW/MCM-48 and NiW/γ-Al2O3 catalysts. The addition of CS2 to the feed could boost the conversion of quinoline HDN and change the product distribution due to modification of the active site distribution of hydrogenation and C-N bond cleavage. Moreover, the stability of the resulting catalysts was also investigated, and no dramatic decrease in HDN conversion was observed in 960 h, which suggests that they could be candidates for industrial HDN catalysts.
γ-Al2O3-supported and unsupported (Ni)MoS 2 for the hydrodenitrogenation of quinoline in the presence of dibenzothiophene
Hein, Jennifer,Hrabar, Ana,Jentys, Andreas,Gutierrez, Oliver Y.,Lercher, Johannes A.
, p. 485 - 499 (2014/03/21)
Supported MoS2/γ-Al2O3 and Ni-MoS2/γ-Al2O3 as well as unsupported Ni-MoS2 were investigated in the hydrodenitrogenation (HDN) of quinoline in the presence of dibenzothiophene (DBT). The supported oxide catalyst precursors had a well-dispersed amorphous polymolybdate structure that led to the formation of a highly dispersed sulfide phase. In contrast, the unsupported catalyst precursor consisted of a mixture of nickel molybdate and ammonium nickel molybdate phases that formed stacked sulfide slabs after sulfidation. On all catalysts, the reaction pathway for the removal of N in quinoline HDN mainly followed the sequence quinoline→1,2,3,4- tetrahydroquinoline→decahydroquinoline→propylcyclohexylamine→ propylcyclohexene→propylcyclohexane. The hydrodesulfurization of DBT proceeded mainly by direct desulfurization towards biphenyl. For both processes, the activity increased in the order MoS2/γ-Al 2O32/unsupported2/γ-Al2O3. The promotion of the MoS 2 phase with Ni enhances the activity of the unsupported catalyst to a greater extent than the supported one. However, the multiply stacked unsupported Ni-MoS2 exhibited lower rates than Ni-MoS 2/γ-Al2O3 because of its lower dispersion. I want to break free (from your nitrogen): Ni and Al 2O3 exert particular effects on the physicochemical and kinetic features of molybdenum oxide species and the corresponding MoS 2 phase. The support maximizes the concentration of active sites, whereas the promoter changes their intrinsic activity. In turn, the support also influences the promotion mechanism. Copyright
Competitive hydrodesulfurization of dibenzothiophene and hydrodenitrogenation of quinoline over unsupported MoS2 catalyst
Farag, Hamdy,Kishida, Masahiro,Al-Megren, Hamid
, p. 173 - 182 (2013/11/19)
The hydrodesulfurization of dibenzothiophene and the hydrodenitrogenation of quinoline were investigated both individually and simultaneously as a mixture over an unsupported synthetic MoS2 catalyst. The reactions were carried out in a batch system under 3 MPa H2 at 340 C. Investigations toward the effect of H2S on the hydrodenitrogenation reaction of quinoline revealed that H2S promoted the transformation of 1,2,3,4-tetrahydroquinoline (THQ1) to ortho-propylaniline (OPA), but had a considerable adverse impact on the transformation of OPA to propylbenzene and its derivatives (C9 products). The hydrodesulfurization of dibenzothiophene proceeded predominantly through a hydrogenation pathway to give cyclohexylbenzene. The hydrodesulfurization of dibenzothiophene was found to be completely inhibited during the initial stages of the reaction, when quinoline was added into the feedstock. The inhibition of the reaction persisted until the quinoline was transformed to a sufficiently low level. Thereafter, the hydrodesulfurization of dibenzothiophene recovered and the reaction proceeded with only moderate inhibition. In contrast, the hydrodenitrogenation of quinoline was significantly enhanced by the presence of dibenzothiophene in the reaction feedstock. The THQ1 and C9 products were the main species obtained from the hydrodenitrogenation reaction of quinoline. The presence of dibenzothiophene enhanced the activity and selectivity toward C9 productions. These results suggested that at least two types of active site were involved in the reaction. Dibenzothiophene could interact with distinct coordinative unsaturated sites, and this could stabilize and increase the acidity of the potential active sites assumed to be responsible for the hydrodenitrogenation reactions.
Ring opening of 1,2,3,4-tetrahydroquinoline and decahydroquinoline on MoS2/γ-Al2O3 and Ni-MoS 2/γ-Al2O3
Gutierrez, Oliver Y.,Hrabar, Ana,Hein, Jennifer,Yu, Yanzhe,Han, Jinyi,Lercher, Johannes A.
, p. 155 - 168 (2013/01/14)
The hydrodenitrogenation of decahydroquinoline (DHQ) and quinoline on MoS2/γ-Al2O3 and Ni-MoS 2/γ-Al2O3 proceeds via two routes. The first one proceeds via DHQ → propylcyclohexylamine → propylcyclohexene → propylcyclohexane, and the ring opening in DHQ is the rate-limiting step. The second route proceeds via 1,2,3,4-tetrahydroquinoline (14THQ) → o-propylaniline → propylcyclohexylamine and propylbenzene with the ring opening of 14THQ and the hydrogenation of o-propylaniline being the rate determining steps (the intrinsic rate of C(sp3)-N bond cleavage being slower in 14THQ than in DHQ). The active sites for the ring opening via Hofmann elimination are acidic -SH groups and basic S2- ions. The parallel conversion of dibenzothiophene (DBT) via direct desulfurization provides increasing concentrations of S2- ions and -SH groups. Nickel facilitates the adsorption of H2S and H2 and the mobility of hydrogen. Thus, the presence of DBT and Ni accelerates the rate of the C(sp3)-N bond cleavage. H2S as sulfur source enhances the ring-opening steps in a minor extent than DBT. The presence of -SH groups and the effect of Ni on them were probed by TPR, TPD and IR-spectroscopy of adsorbed 2,6-dimethylpyridine.
