The “Borrowing Hydrogen Strategy” by Supported Ruthenium Hydroxide Catalysts: Synthetic Scope of Symmetrically and Unsymmetrically Substituted Amines

The N‐alkylation of ammonia (or its surrogates, such as urea, NH₄HCO₃, and (NH₄)₂CO₃) and amines with alcohols, including primary and secondary alcohols, was efficiently promoted under anaerobic conditions by the easily prepared and inexpensive supported ruthenium hydroxide catalyst Ru(OH)_x/TiO₂. Various types of symmetrically and unsymmetrically substituted “tertiary” amines could be synthesized by the N‐alkylation of ammonia (or its surrogates) and amines with “primary” alcohols. On the other hand, the N‐alkylation of ammonia surrogates (i.e., urea and NH₄HCO₃) with “secondary” alcohols selectively produced the corresponding symmetrically substituted “secondary” amines, even in the presence of excess amounts of alcohols, which is likely due to the steric hindrance of the secondary alcohols and/or secondary amines produced. Under aerobic conditions, nitriles could be synthesized directly from alcohols and ammonia surrogates. The observed catalysis for the present N‐alkylation reactions was intrinsically heterogeneous, and the retrieved catalyst could be reused without any significant loss of catalytic performance. The present catalytic transformation would proceed through consecutive N‐alkylation reactions, in which alcohols act as alkylating reagents. On the basis of deuterium‐labeling experiments, the formation of the ruthenium dihydride species is suggested during the N‐alkylation reactions.     

硫酸亚铈催化的芳香化合物与苄基醇、烯丙醇类化合物以及苄基氯的傅-克烷基化反应研究

硫酸亚铈作为一种便宜的和有效的催化剂催化芳香化合物与苄基醇、烯丙醇类化合物和苄基氯的傅-克烷基化反应. 在1～10 mol%的硫酸亚铈存在下, 芳香化合物分别与苄基醇、烯丙醇类化合物和苄基氯能够顺利有效地进行傅-克烷基化反应. 此外, 催化剂能回收, 再次使用三次也没有明显地失去催化活性.     

Facile Synthesis of 2‐Alkylthio‐3‐alkyl‐5‐phenylmethylidene‐4H‐imidazol‐4‐ones

2‐Alkylthio‐3‐alkyl‐5‐phenylmethylidene‐4H‐imidazol‐4‐ones 6 were synthesized by N‐alkylation and S‐alkylation of 2‐thioxo‐5‐phenylmethylidene‐4‐imidazolidinone 5, which was obtained via cyclization of vinyl isothiocyanate 4 with excess ammonium hydroxide (28% NH₃ in water).     

Chlorogallate(III) ionic liquids: Synthesis, acidity determination and their catalytic performances for isobutane alkylation

A series of triethylammonium-based chlorogallate(Ⅲ) ionic liquids with varied Lewis acidity was synthesized, characterized, and firstly applied to isobutane alkylation. The [Et3NHCl]-GaCl3 with χGaCl3 = 0.65 displayed a potential catalytic activity for the alkylation. The addition of copper halide into the chlorogallate(Ⅲ) ionic liquids dramatically enhanced the alkylation reaction. Up to 70.1% C8 selectivity and 91.3 RON were achieved with the [Et3NHCl]-GaCl3-CuCl (χGaCl3 = 0.65, CuCl = 5% mol) under 0.5 MPa, 900 r/min, 15 min, 288 K using the industrial C4 cut (isobutane/butene = 10). These results indicate that the chlorogallate(Ⅲ) system may be used as a promising catalyst for the C4 alkylation.     

On the Alkylation of 5-Fluorouracil-Some Recent Findings

Since its discovery 5-fluorouracil ¹(1,5-FU), an important anticancer drug, has been the subject of study for the preparation of some suitable derivatives² which may have better therapeutic efficacy. These are prepared through silylation method³, mercuri salt method⁴ and direct alkylation method⁵ of 5-FU. It was reported⁵ that the direct alkylation of 5-FU with saturated and allylic type halides under controlled conditions occur at N₃ (3-) and N₁ (1-) position respectively in contrast to alkylation of uracil where N₁ alkylated products are obtained in both cases. The position of alkylation in 5-FU was determined, with analogy from uracil⁶, by the bathochromic shift in UV from the neutral pH to alkaline pH of the 3-substituted product compared to no such shift of the 1-substituted product.     

Functionalization of Quinazolin‐4‐ones Part 1: Synthesis of Novel 7‐Substituted‐2‐thioxo Quinazolin‐4‐ones from 4‐Substituted‐2‐Aminobenzoic Acids and PPh3(SCN)2

4‐(Nitro, amino, acetylamino)‐2‐aminobenzoic acid were allowed to react with PPh₃(SCN)₂ and gave the crossholding 7‐nitro, 7‐acetylamino‐ and 7‐amino‐2‐thioxo quinazolin‐4‐ones respectively. The nature of the substituent at position 4 of the 2‐aminobenzoic acids has significant influence on the outcome of the cyclisation reaction with PPh₃(SCN)₂. Similarly, the nature of the substituent at position 7 of the 2‐substituted quinazolin‐4‐ones significantly affected the ease with which alkylation reactions could be performed. The alkylation selectivity of the 7‐ substiuted‐2‐thioxo quinazolin‐4‐ones was found to depend on the nature of the alkyl halide and the nature of the substituent at position 2.     

Alkylation of benzene with 4-methylcyclohexanol in the presence of sulfuric acid

Alkylation of benzene with 4-methylcyclohexanol in the presence of methylcyclohexane and 96, 88, and 80% H₂SO₄ has been studied. It was established that depending on the solubility of the starting components in sulfuric acid, alkylation occurs in the inorganic phase or on the interface between the organic and inorganic phases. The yield and composition of the catalysate are determined to a significant degree by the extent of the alkylation process and intramolecular hydride transfers.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 121–125, January, 1990.     

Synthesis of polyisobutylene with arylamino terminal group by combination of cationic polymerization with alkylation

The controlled cationic polymerization of isobutylene (IB) initiated by H₂O as initiator and TiCl₄ as coinitiator was carried out in n‐Hexane/CH₂Cl₂ (60/40, v/v) mixture at −40 °C in the presence of N,N‐dimethylacetamide (DMA). Polyisobutylene (PIB) with nearly theoretical molecular weight (M_n = 1.0 × 10⁴ g/mol), polydispersity (M_w/M_n) of 1.5 and high content (87.3%) of reactive end groups (tert‐Chlorine and α‐double bond) was obtained. The Friedel‐Crafts alkylation of triphenylamine (TPA) with the above reactive PIB was further conducted at different reactions, such as [TPA]/[PIB], solvent polarity, alkylation temperature, and time. The resultant PIBs with arylamino terminal group were characterized by ¹H NMR, UV, and GPC with RI/UV dual detectors. The experimental results indicate that alkylation efficiency (A_eff) increased with increases in [TPA]/[PIB], reaction temperature, and reaction time and with a decrease in solvent polarity. The alkylation efficiency could reach 81.0% at 60/40(v/v) mixture of n‐Hex/CH₂Cl₂ with [TPA]/[PIB] of 4.49 at 50 °C for 54 h. Interestingly, the synthesis of PIB with arylamino terminal group could also be achieved in one pot by combination of the cationic polymerization of IB initiated by H₂O/TiCl₄/DMA system with the successive alkylation by further introduction of TPA. Mono‐, di‐ or tri‐alkylation occurred experimentally with different molar ratio of [TPA]/[PIB]. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 936–946, 2008     

H3PW12O40/mpg‐C3N4 as an efficient and reusable catalyst in the alkylation of o‐xylene and styrene

A heterogeneous catalyst (HPW/mpg‐C₃N₄) for the alkylation of o‐xylene and styrene reaction was acquired by the immobilization of phosphotungstic acid (HPW) on mesoporous graphitic carbon nitride (mpg‐C₃N₄) through electrostatic interaction. The results of Fourier transform infrared spectroscopy (FT‐IR), X‐ray powder diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) proved that HPW was successfully immobilized on the protonated mpg‐C₃N₄ by electrostatic interaction. The textural properties and morphology of HPW/mpg‐C₃N₄ were characterized by N₂ adsorption–desorption, scanning electron microscopy (SEM). Among them, 40% HPW/mpg‐C₃N₄ displays the best catalytic performance in the alkylation reaction with 91.8% yield and 96.5% selectivity to 1, 2‐diphenylethylane. Moreover, protonated mpg‐C₃N₄ not only displays as a support to facilitate great dispersion of HPW but also promotes the alkylation product diffusion effectively. Besides, the HPW/mpg‐C₃N₄ catalyst could be recycled easily without significant loss of catalytic activity, which is demonstrate by the recyclability of HPW/mpg‐C₃N₄ catalyst test.     

A Simple Synthesis of Polyfunctionalized 4‐Aminopyrazolidin‐3‐ones as ‘Aza‐deoxa’ Analogs of D‐Cycloserine

A simple five‐step synthesis of fully substituted (4RS,5RS)‐4‐aminopyrazolidin‐3‐ones as analogs of D ‐cycloserine was developed. It comprises a two‐step preparation of 5‐substituted (4RS,5RS)‐4‐(benzyloxycarbonylamino)pyrazolidin‐3‐ones, reductive alkylation at N(1), alkylation of the amidic N(2) with alkyl halides, and simultaneous hydrogenolytic deprotection/reductive alkylation of the primary NH₂ group. The synthesis enables an easy stepwise functionalization of the pyrazolidin‐3‐one core with only two types of common reagents, aldehydes (or ketones) and alkyl halides. The structures of products were elucidated by NMR spectroscopy and X‐ray diffraction.     

吡啶离子液体催化作用下的FCC汽油烷基化脱硫

合成一种Brønsted酸性离子液体[BPY]HSO₄,采用红外光谱和核磁共振对其进行表征。以[BPY]HSO₄为催化剂,对FCC汽油进行烷基化脱硫,考察反应温度、反应时间和剂油质量比对脱硫效果的影响及脱硫前后FCC汽油性质的变化,并对[BPY]HSO₄进行了再生。结果表明,在反应温度为65 ℃、反应时间为90 min和剂油质量比为0.09的条件下,FCC汽油的硫含量从580.0 μg/g降至6.4 μg/g,脱硫率为98.90%,满足中国国Ⅴ车用汽油硫含量标准(<10 μg/g);脱硫前后硫分布变化表明,在[BPY]HSO₄的催化作用下,前170 ℃馏分油中硫化物大部分转移到后170 ℃重馏分中,重馏分中硫化物可采用加氢方法进行脱除;PONA组成变化表明,烷基化脱硫过程对FCC汽油的烃类组成影响较小,且脱硫前后辛烷值变化不大;[BPY]HSO₄经萃取再生后可循环使用。     

Kinetic studies of hydrazine and 2‐hydroxyethylhydrazine alkylation by 2‐chloroethanol: Influence of a strong base in the medium

To optimize yields, the study of reaction kinetics related to the synthesis of 2‐hydroxyethylhydrazine (HEH) obtained from the alkylation of N₂H₄ by 2‐chloroethanol (CletOH) was carried out with and without sodium hydroxide. In both cases, the main reaction of HEH formation was followed by a consecutive, parallel reaction of HEH alkylation (or dialkylation of N₂H₄), leading to the formation of two isomers: 1,1‐di(hydroxyethyl)hydrazine and 1,2‐di(hydroxyethyl)hydrazine. In this study, hydrazine and hydroxyalkylhydrazine alkylations followed S_N2 reactions triggered directly by CletOH or indirectly in the presence of a strong base by ethylene oxide, an intermediate compound. The kinetics was studied in diluted mediums by quantifying HEH and CletOH by gas chromatography and gas chromatography coupled with mass spectrometry (GC‐MS). The activation parameters of each reaction and the influence of a strong base present in the medium on the reaction mechanisms were established. A global mathematical treatment was applied for each alternative. It allowed modeling the reactions as a function of reagent concentrations and temperature. In the case of direct alkylation by CletOH, simulation was established for semi‐batch and batch syntheses and was confirmed in experiments for concentrated mediums (1.0 M ≤ [CletOH]₀ ≤ 3.2 M and 15.7 M ≤ [N₂H₄]₀ ≤ 18.8 M). Simulation therefore permits the prediction of the instantaneous concentration of reagents and products, in particular ethylene oxide concentration in the case of indirect alkylation, which must be as weak as possible. © 2009 Wiley Periodicals, Inc. Int J Chem Kinet 41: 382–393, 2009     

Synthesis of new 1,4- and 1,5-disubstituted N-ethyl acetate and N-α-butyro-γ-lactone alkylimidazole derivatives as N-acylhomoserine lactone analogs

New alkylimidazoles functionalized with a homoserine lactone or an alkyloxycarbonyl moiety have been synthesized as N-acylhomoserine lactones (AHLs) analogs. The 1,4-disubstituted imidazole derivatives were prepared by alkylation of 4(5)-alkylimidazoles with α-bromo-γ-butyrolactone or ethyl α-bromoacetate. An alternative route was preferred for the synthesis of their 1,5-disubstituted counterparts based on the use of a N₁-protected alkylimidazole, its alkylation to an N₃-imidazolyl-α-acetate and deprotection to the desired 1,5-disubstituted esters and subsequent alkylation of the acetate moiety with cyclic ethylene sulfate followed by acid-catalyzed cyclization. The ability to modulate bacterial quorum sensing of all new compounds was compared to that of previously reported AHL analogs in which the amide bond is replaced by a heterocyclic group.     

A 3D Iodoplumbate Semiconducting Open Framework with Visible‐light‐induced Photocatalytic Performance

Employing in situ N‐alkylation of the conjugated compound 9,10‐bis(4‐pyridyl)anthracene (bpanth) as structure‐directing agent, a 3D inorganic‐organic hybrid iodoplumbate, [Me₂(bpanth)][Pb₄I₁₀] ( 1 ), was solvothermally prepared. The in situ N‐alkylation of bpanth with alcohols was investigated. 1 features a novel 3D open framework based on an interesting Pb₆I₂₄ cluster. UV/Vis spectroscopy analyses indicate that 1 is a potential semiconductor material with a narrow energy gap of 2.06 eV. It exhibits good catalytic activity in the visible‐light‐drived degradation of an organic dye. This work further illustrates that introducing conjugated organic molecules as templates is conducive to achieving semiconducting hybrid halometallates with narrow band gaps.     

Catalysis and deactivation of SO 4 2− /ZrO2 solid acid on the alkylation of benzene with 1-dodecene

Catalysis and deactivation of SO₄²⁻/ZrO₂ solid acid on the alkylation of benzene and 1-dodecene were studied by the characterization of XRD, BET, IR, TG/DTA, and NH₃-TPD techniques and the determination of the 1-dodecene conversion, the yield of dodecylbenzene and the selectivity of linear alkylbenzene respectively. In addition, some treatment methods, such as the extraction with benzene or THF as solvent, and the calcinations with or without the dipping of H₂SO₄ in air, were respectively used to recover the activity of deactivated catalyst. The results indicate that SO₄²⁻/ZrO₂ solid acid shows higher catalytic activity for the alkylation of benzene and 1-dodecene with nearly 100% of 1-dodecene conversion and more than 80% of dodecylbenzene yield, and higher selectivity of 2-LAB. The activity of catalyst for the alkylation of benzene is in proportion to the content and the strength of medium acid site. However, the distinct deactivation of catalyst was also obversed in the alkylation. According to the characterization of deactivated catalyst, the accumulation of hydrocarbon fragment and the removal of are mainly reasons of SO₄²⁻/ZrO₂ deactivation. The SO₄²⁻/ZrO₂ calcinated at higher temperature is apt to deactivate. The treatment by extraction with solvent or calcinations can recover the catalytic activity of spent catalyst at a certain extent, especially calcination with the dipping of H₂SO₄. Published in Russian in Kinetika i Kataliz, 2009, Vol. 50, No. 3, pp. 455–463. The article is published in the original.     

C9 Fraction Alkylation Desulfurization over Amberlyst 36 Resin:The Kinetics of 2‐Ethylthiophen, 2,5‐Dimethylthiophene,and 2‐n‐Propylthiophene with Isoamylene

C₉ fraction is the by‐products of catalytic reforming and ethylene cracker; it is considered as a kind of petroleum resin raw material. Recently, it was studied for the use as a gasoline additive to enhance the economic benefits. However, C₉ fractions are getting higher in sulfur contents. As conventional hydrotreating technology leads to significant octane number loss and processing costs, the alkylation desulfurization process, which could reduce the sulfuric compounds to hydrogen sulfide by catalytic alkylation with olefins and distillation followed by, is a rather attractive way of reducing the sulfur of C₉ fraction. In this paper, different kinds of thiophenic compounds, including 2‐ethylthiophen, 2,5‐dimethylthiophene, and 2‐n‐propylthiophene, were selected as the model compounds. Thiophenic compounds were studied first by the alkylation reaction over macroporous sulfonic resin Amberlyst 36, and the octane number of C₉ fraction was measured. It was found that isoamylene and Amberlyst 36 resin had a significant effect on the alkylation desulfurization of thiophenic compounds with the conversion, reaching to above 99%. And the octane number of C₉ fraction was increased by alkylation desulfurization over Amberlyst 36 resin. Moreover, the alkylation of thiophenic sulfurs could be described as a pseudo–first–order reaction as well as the reaction rate constant, and the activation energy of alkylation reactions was calculated.     

KF/Al2O3‐Mediated N‐Alkylation of Amines and Nitrogen Heterocycles and S‐Alkylation of Thiols

KF/Al₂O₃ efficiently catalyzes N‐alkylation of heterocyclic, primary, and secondary amines and S‐alkylation of thiols with a variety of alkyl halides. The N‐alkylation and S‐alkylation adducts were produced in good to excellent yields and in short times.     

Highly Active La(III)-Based Metal-Organic Framework as a Heterogeneous Lewis Acid Catalyst for Friedel-Crafts Alkylation

In this study, a novel La(III)-based two-dimensional (2D) metal-organic framework, [La_2/3(qptca)_1/2] (referred to as SLX-2), from LaCl₃ and 1,1′ : 4′,1′′ : 4′′,1′′′ : 4′′′,1′′′′-quinquephenyl]-2,2′′,2′′′′,5′′-tetracarboxylic acid (H₄qptca) was synthesized by conventional solvothermal method and thoroughly characterized by using X-ray single-crystal diffraction, powder X-ray diffraction, and thermogravimetric analyses. The 2D SLX-2 features a unique lanthanum center exposed to the skeleton and was used as an efficient Lewis acid catalyst for the Friedel-Crafts alkylation of indole and pyrrole with β-nitrostyrene along with a wide substrate scope, giving the desired products in good-to-high yields under the optimal reaction conditions. Furthermore, the catalyst was used for twenty cycles, with nearly no effect on its activity, and the reaction was heterogeneous in nature. Moreover, compared to the previous hydrogen-bond-donating MOF catalysts for such alkylation reactions, SLX-2 showed an excellent stability toward harsh acidic and basic environment, and gave comparable catalytic activities.     

Exploiting the Chiral Ligands of Bis(imidazolinyl)- and Bis(oxazolinyl)thiophenes—Synthesis and Application in Cu-Catalyzed Friedel–Crafts Asymmetric Alkylation

Five new C₂-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The utility of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subsequently, the optimized tridentate ligand L5 and Cu(OTf)₂ catalyst (15 mol%) in toluene for 48 h promoted Friedel–Crafts asymmetric alkylation in moderate to good yields (up to 76%) and with good enantioselectivity (up to 81% ee). The bis(oxazolinyl)thiophene ligands were more potent than bis(imidazolinyl)thiophene analogues for the asymmetric induction of the Friedel–Crafts asymmetric alkylation.     

New C(4)‐Functionalized Colchicine Derivatives by a Versatile Multicomponent Electrophilic Aromatic Substitution

Electrophilic alkylation of colchicine at C(4) was accomplished by a multicomponent aromatic electrophilic substitution reaction with electrophilic aldehydes and carboxylic acids or amides in H₂SO₄. A series of new derivatives were obtained and evaluated for their antiproliferative effect towards various tumor cell lines, and their stimulatory effect on the development of polarity in human neutrophils.