A Scrutiny on the Reductive Amination of Carbonyl Compounds Catalyzed by Homogeneous Rh(I) Diphosphane Complexes

The reductive amination of a series of aldehydes with secondary amines and H₂ in the presence of a homogeneous Rh-diphosphane catalyst was studied in order to establish a general mechanism of this reaction and to identify conditions for the improvement of the amine/alcohol ratio in the product. Several possible intermediates as constituents of changing equilibria like half-aminals, N,O-acetals and aminals were observed in the reaction mixture by means of ¹H NMR spectroscopy. In individual trials, these compounds could be successfully hydrogenated under the conditions applied for reductive amination (50 bar H₂ pressure, MeOH). Some evidence is accumulated that half-aminals and N,O-acetals might be key intermediates of the reductive amination. Moreover, it was found that the formation of the undesired product alcohol is likely based on the reduction of the starting carbonyl compound. However, due to numerous equilibria consisting of several intermediates, general conclusions are hard to be drawn. Proof will be given that, in several cases, the efficiency of the reductive amination of aliphatic aldehydes can be significantly improved by prehydrogenation of the cationic [Rh(dppb)(COD)]⁺ complex.     

羰基化合物直接还原胺化合成伯胺催化剂研究进展

胺类化合物是一类重要的化工原料和中间体，在农药、医药、染料、高分子聚合物等领域有着广泛的应用。通过羰基化合物（醛或酮类）的还原胺化来制备胺类化合物是当前的研究热点。研究表明，贵金属基和非贵金属基的多相和均相催化剂均能够高效催化醛或酮类的还原胺化反应。本文对近年来羰基化合物直接还原胺化（或一锅法）合成伯胺的研究现状进行了综述，包括还原胺化反应、催化剂、反应条件、底物适用范围和催化作用机制等，其中重点阐述了直接还原胺化催化剂的研究进展。文章指出：通常多相催化剂具有活性高以及可重复使用等优点，而均相催化剂的优势在于催化效率高，伯胺选择性高；另一方面，以Pd、Rh、Ru等为代表的贵金属催化剂催化性能优异，但价格昂贵，因此可采用Co、Ni等性能同样优异但价格相对低廉的非贵金属催化剂以降低成本。文中提出，催化效率高、反应条件温和、普适性高的羰基化合物还原胺化催化剂应成为未来重点研究方向。     

Catalytic Amination of Octanol for Synthesis of Trioctylamine and Catalyst Characterization

Abstract  

Synthesis of trioctylamine by the amination of octanol and ammonia under atmospheric pressure over an excellent Ni–Cu catalyst supported on diatomite is studied in this article. The key factor for the synthesis is the preparation of catalyst with a high activity and selectivity. The activity and selectivity can be adjusted by varying the Ni to Cu ratios. The optimum molar ratio of Ni to Cu was 1.25:1. For the catalyst with a Ni/Cu ratio of 1.25:1, the conversion of octanol and the selectivity of trioctylamine reached 100 and 97.3%, respectively, at 5 h. The reaction of dioctylamine with octanol was the rate-determining step for the formation of trioctylamine. The Physical properties of catalysts, such as particle size, Brunauer–Emmett–Teller (BET) surface area, valence state of catalyst elements, morphology and reduction properties of catalysts were investigated by using X-ray diffraction, nitrogen adsorption–desorption isotherms (BET), X-ray photoelectron spectroscopy, Transmission electron microscopy, and temperature programmed reduction, respectively. The reaction scheme of catalytic amination of octanol with ammonia was discussed.     

乙醇胺还原胺化合成乙二胺的催化剂研究进展

介绍了乙醇胺催化还原胺化反应合成乙二胺的机理及影响反应的工艺条件:叙述了乙醇胺还原胺化反应的催化剂研究进展,讨论了催化活性中心、催化剂栽体、助剂等对胺化反应的影响.认为乙醇胺还原胺化法是一种适合于大规模、连续化生产乙二胺的清洁工艺,将成为未来发展的必然趋势.     

An Efficient Recyclable Polymer Supported Copper(II) Catalyst for C–N Bond Formation by <Emphasis Type="Italic">N</Emphasis>-Arylation

Abstract  

Polymer supported Cu(II) catalyst was prepared, characterized and employed for the N-arylation and amination reaction of N–H heterocycles with aryl halides as well as arylboronic acids to afford the corresponding coupled products in good to excellent yields. This catalyst can be used several times with consistent catalytic activity.     

Reductive Amination of Triacetoneamine with <Emphasis Type="Italic">n</Emphasis>-Butylamine Over Cu–Cr–La/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

Abstract  

A series of Cu-based catalysts were prepared and examined for the reductive amination of triacetoneamine with n-butylamine, thereinto, Cu–Cr–La/γ-Al₂O₃ showed excellent results. The catalysts were studied by XRD, XPS, H₂-TPR and NH₃-TPD. It was found that doped Cr remarkably enhanced the activity of Cu/γ-Al₂O₃ due to better dispersion of Cu⁰, which is believed to be the active site for the reductive amination. Additionally, it was obvious that introduction of La to Cu–Cr/γ-Al₂O₃ led to a higher selectivity and longer lifetime. The reaction parameters were optimized and N-butyl-2,2,6,6-tetramethyl-4-piperidinamine was obtained in a yield of 94%.     

Synthesis and Catalytic Properties of Carbon-Nanotube-Supported RuO<Subscript>2</Subscript> Catalyst Encapsulated in Silica Coating

Abstract  

A carbon-nanotube-supported RuO₂ nanocatalyst encapsulated in thin silica layer was successfully synthesized. The prior formation of silica over RuO₂ nanoparticles effectively hindered catalyst aggregation at high temperatures. The significant improvement of the resistance to sintering and the catalytic selectivity were demonstrated in competitive oxidation of n-butanol and i-butanol and methanol oxidative dehydrogenation.     

Unexpected Support Effect in Hydrotreating: Evidence of a Metallic Character for ReS<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and ReS<Subscript>2</Subscript>/SiO<Subscript>2</Subscript> Catalysts

Abstract  

Rhenium sulfide based catalysts were prepared by the incipient wetness impregnation method over alumina and silica supports and evaluated for 4,6-dimethyldibenzothiophene hydrodesulfurization in a high-pressure stirred-tank reactor. The catalyst prepared over silica was about six times more active for hydrodesulfurization than the corresponding catalyst prepared over alumina and a NiMo/Al₂O₃ industrial reference catalyst. This surprising and positive SiO₂ support effect was explained by a metallic character of the supported sulfide, which was demonstrated using a kinetic approach of competitive hydrogenations and by XPS characterization.     

Oxidative Cleavage of C=C Bond of Styrene and Its Derivatives with H<Subscript>2</Subscript>O<Subscript>2</Subscript> using Vanadyl (IV) Acetylacetonate Anchored SBA-15 Catalyst

Abstract  

Cleavage of C=C bond of styrene and its derivatives into two carbonyl compounds with H₂O₂ is accomplished at mild conditions using Vanadyl(IV) acetylacetonate anchored SBA-15 catalyst, which is prepared and characterized by BET surface area, low angle XRD and FT-IR. It is a highly efficient, recyclable and reusable catalyst.     

Catalytic synthesis ofdl-serine and glycine from glycerol

dl-serine (dl-Ser), glycine (Gly), serinol (SerOH) and related compounds were catalytically derived from glycerol (GLY). Catalytic oxidation in the presence of ammonia of GLY, followed by hydrogen treatment over noble metals, to achieve direct synthesis of amino acids is not practical. Reductive amination over an Ru-Pd/C catalyst of glyceric acid, one of the oxidation products of GLY, was effective fordl-Ser synthesis. Gly was catalytically formed fromdl-Ser by dehydrogenation and decarbonylation in hydrogen atmosphere. Catalytic oxidation of SerOH prepared by reductive amination over an Rh-Pd/C catalyst of dihydroxyacetone, another oxidation product of GLY, was also effective fordl-Ser synthesis. A new route fordl-Ser and Gly from GLY is presented.dl-alanine and γ-aminobutyric acid also formed, depending on reaction conditions.     

Pd催化剂上乙酰丙酸与腈还原胺化制吡咯烷酮类化合物

采用柠檬酸络合法,通过调整CeO2含量制备出多组CeO2-Al2O3复合氧化物,以此为载体用沉积-沉淀法制备了一系列Pd/CeO2-Al2O3催化剂,采用XRD、N2吸附-脱附、TEM、XPS等方法对催化剂的物化性质进行了表征,研究了催化剂对生物质基乙酰丙酸与腈“一锅法”还原胺化合成N-取代基-5-甲基-2-吡咯烷酮类化合物的催化性能。结果表明,在温和的反应条件下（90℃、1.5 MPa H2）,Pd/10%CeO2-Al2O3催化剂上乙酰丙酸与苯甲腈反应5 h,N-苄基-5-甲基-2-吡咯烷酮收率高达87.5%。在该催化剂上,乙酰丙酸与其他多种腈类化合物反应同样获得了较高的吡咯烷酮衍生物收率（76.3%-87.4%）。催化剂重复使用5次后,其活性无明显下降。     

磺基甜菜碱的合成研究进展

磺基甜菜碱具有性能温和、界面活性高、抗二价阳离子能力强等优点,被广泛应用于洗涤剂、化妆品、石油开采等领域。本文介绍了以胺为原料,经叔胺化-季铵化两步法合成磺基甜菜碱的合成工艺进展,重点阐述了制备叔胺中间体的4种方法,即卤化胺化法、醇一步催化胺化法、甲醛加氢法和羰基还原胺化法。从原料性能、收率、环保性、可操作性等方面进行了分析比较,讨论了各方法存在的问题及工业化的可行性。此外,对叔胺中间体的季铵化过程中所用试剂3-氯-2-羟基丙磺酸钠和磺酸内酯进行了比较,最后指出羰基还原胺化法是实现绿色工业化生产应该努力的方向,而3-氯-2-羟基丙磺酸钠是一种经济、绿色、环保的季铵化试剂。     

苯丙酮酸在Pd/C催化剂上还原胺化合成DL-苯丙氨酸

以苯丙酮酸 (PPA)在Pd/C催化剂上还原胺化合成DL 苯丙氨酸 (Phe)。实验表明 :在 5 5℃、1 0MPa,苯丙酮酸初始质量浓度 ρ(PPA) =6 0g/L ,n(NH3)∶n(PPA) =3 0∶1 0 ,还原胺化 3h ,苯丙氨酸收率在 95 %以上 ,产品纯度w(DL Phe) >96 % ,并通过红外光谱、核磁共振对产物结构进行了确证     

Acetalation of Pentaerithritol Catalyzed by an Al-Pillared Saponite

Abstract  

Acetalation of pentaerithritol has been carried out in the presence of an Al-pillared saponite. Several carbonyl compounds were used, including aldehydes and ketones. Yields between 72 and 93% were obtained in all cases, except in the case of veratraldehyde where the carbonyl group was blocked. The high conversion could be explained by diffusion effects of intermediates and electronic effects between the reactants in the transition state. The catalyst was found to be active after three cycles.     

Ca-Containing Mesoporous Silica as a Solid Base Catalyst for the Knoevenagel Condensation Reaction

Abstract  

We synthesized Ca-containing FSM-16 (Ca-FSM-16) for use as a solid base catalyst for the Knoevenagel condensation reaction. Extended X-ray absorption fine structure (EXAFS) results indicated that Ca species were introduced as a calcium silicate-like phase with distorted tetrahedral coordination into the pore walls of FSM-16. Compared with conventional aminopropyl-functionalized mesoporous silica, Ca-FSM-16 showed higher activity as a solid-base catalyst for the Knoevenagel condensation reaction.     

脂肪伯胺的合成及工业化研究进展

有机胺在化工、医药、生命科学等领域有着广泛的应用,可作为染料、日用品原料以及抗生素、生物碱、临床医学药物等。在众多胺类化合物中,伯胺是最基础的结构单元,其应用在胺类化合物中也最为广泛。随着经济社会的快速发展与人们生活质量的提高,伯胺,尤其是脂肪伯胺的市场需求量与日俱增,脂肪伯胺的合成及工业化制备已成为一个重要领域。经过了数十年的发展,脂肪伯胺的生产技术已经取得了巨大的成果,但仍然存在一些问题,例如苛刻的反应条件、催化剂性能不足、污染严重、工艺复杂等。本文以脂肪伯胺的工业生产以及热点制备方法为研究对象,针对工业上制备脂肪伯胺的工艺进行了汇总归纳(包括卤代烃胺化法、醇还原胺化法,腈加氢还原法、烯烃直接胺化法、羧酸胺化法等),并举例说明各制备方法在工业生产中的实际应用,分析比较各工艺方案的优劣,并对当前的研究热点——通过羰基还原胺化制备脂肪伯胺的方法进行了研究进展的阐述,指出该制备方法在未来工业应用的潜力与挑战。     

Mono and Bifunctional Catalysts for Styrene Oxide Isomerization or Hydrogenation

Abstract  

Styrene oxide can be effectively isomerized to phenyl-acetaldehyde (98%) over amorphous silica alumina catalysts under very mild liquid phase conditions. On the other hand, a copper catalyst prepared using a silica zirconia support gave up to 80% yield in the hydrogenation of styrene oxide to 2-phenyl-ethanol.     

Reductive amination of ethanol to ethylamines over Ni/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts

Ni(x)/Al₂O₃ (x=wt%) catalysts with Ni loadings of 5–25 wt% were prepared via a wet impregnation method on an γ-Al₂O₃ support and subsequently applied in the reductive amination of ethanol to ethylamines. Among the various catalysts prepared, Ni(10)/Al₂O₃ exhibited the highest metal dispersion and the smallest Ni particle size, resulting in the highest catalytic performance. To reveal the effects of reaction parameters, a reductive amination process was performed by varying the reaction temperature (T), weight hourly space velocity (WHSV), and NH₃ and H₂ partial pressures in the reactions. In addition, on/off experiments for NH₃ and H₂ were also carried out. In the absence of NH₃ in the reactant stream, the ethanol conversion and selectivities towards the different ethylamine products were significantly reduced, while the selectivity to ethylene was dominant due to the dehydration of ethanol. In contrast, in the absence of H₂, the selectivity to acetonitrile significantly increased due to dehydrogenation of the imine intermediate. Although a small amount of catalyst deactivation was observed in the conversion of ethanol up to 10 h on stream due to the formation of nickel nitride, the Ni(10)/Al₂O₃ catalyst exhibited stable catalytic performance over 90 h under the optimized reaction conditions (i.e., T=190 °C, WHSV=0.9 h^?1, and EtOH/NH₃/H₂ molar ratio=1/1/6).     

Photometric Characterization of the Reductive Amination Scope of the Imine Reductases from Streptomyces tsukubaensis and Streptomyces ipomoeae

Imine reductases (IREDs) have emerged as promising enzymes for the asymmetric synthesis of secondary and tertiary amines starting from carbonyl substrates. Screening the substrate specificity of the reductive amination reaction is usually performed by time-consuming GC analytics. We found two highly active IREDs in our enzyme collection, IR-20 from Streptomyces tsukubaensis and IR-Sip from Streptomyces ipomoeae, that allowed a comprehensive substrate screening with a photometric NADPH assay. We screened 39 carbonyl substrates combined with 17 amines as nucleophiles. Activity data from 663 combinations provided a clear picture about substrate specificity and capabilities in the reductive amination of these enzymes. Besides aliphatic aldehydes, the IREDs accepted various cyclic (C₄–C₈) and acyclic ketones, preferentially with methylamine. IR-Sip also accepted a range of primary and secondary amines as nucleophiles. In biocatalytic reactions, IR-Sip converted (R)-3-methylcyclohexanone with dimethylamine or pyrrolidine with high diastereoselectivity (>94–96 % de). The nucleophile acceptor spectrum depended on the carbonyl substrate employed. The conversion of well-accepted substrates could also be detected if crude lysates were employed as the enzyme source.     

Silica Supported Sodium Hydrogen Sulfate and Amberlyst‐15: Two Efficient Heterogeneous Catalysts for Facile Synthesis of Bis‐ and Tris(1H‐indol‐3‐yl)methanes from Indoles and Carbonyl Compounds[1]

Bis‐ and tris(1H‐indol‐3‐yl)methanes are synthesized in high yields by an electrophilic substitution reaction of indoles with carbonyl compounds under mild reaction conditions using two efficient heterogeneous catalysts, silica supported sodium hydrogen sulfate (NaHSO₄⋅SiO₂) and amberlyst‐15. The second catalyst can be reused.