scholarly journals CYCLIZATION AND HYDROGENATION OF (+)-CITRONELLAL TO MENTHOLS OVER ZnBr2 AND Ni CATALYSTS SUPPORTED ON γ-Al2O3

2010 ◽  
Vol 10 (2) ◽  
pp. 201-206 ◽  
Author(s):  
Elvina Dhiaul Iftitah ◽  
M. Muchalal ◽  
Wega Trisunaryanti ◽  
Ria Armunanto
Keyword(s):  
Mild Condition ◽  
Hydrogen Atmosphere ◽  
Nitrogen Atmosphere ◽  
High Yield ◽  
Second Step ◽  
Ni Catalysts ◽  
One Step ◽  
The One ◽  
Al2o3 Catalyst ◽  
Very High

Two steps transformation of (+)-citronellal, cyclization and hydrogenation, on ZnBr2/γ-Al2O3 and Ni/γ-Al2O3 catalyst have been realized with the selectivity to cyclization products (isopulegols) was very high (yield up to ~92.58%) over ZnBr2/γ-Al2O3 under mild condition (90 °C and 1 atm nitrogen atmosphere) with high Brønsted acid concentration, while at the same time very low cyclization rates were achieved over Ni/γ-Al2O3 with low or no Brønsted acidity, respectively. The highest cyclization rates were observed over Ni/ZnBr2/γ-Al2O3 under mild condition (90 °C and 1 atm hydrogen atmosphere). The second step transformation towards cyclization products, hydrogenation to menthols, was performed with Ni/γ-Al2O3 under hydrogen atmosphere. Surprisingly the one-step transformation of (+)-citronellal into menthols was investigated over Ni/γ-Al2O3 with yield ~84% under hydrogen atmosphere (90 °C, 1 atm) by exploiting the presence of acidic and hydrogenation sites on the catalyst surface. On the Ni/γ-Al2O3 catalyst it was found that the cyclization of (+)-citronellal to isopulegols occurs on the surface of the support. In the presence of the noble metal, the isopulegols are further hydrogenated to the menthols.   Keywords: cyclization, hydrogenation, citronellal, isopulegol, menthol

One-step catalytic amination of naphthalene to naphthylamine with exceptional yield

2020 ◽  
Vol 22 (9) ◽  
pp. 2744-2749
Author(s):  
Fang Hao ◽  
Xin Wang ◽  
Linfang Huang ◽  
Wei Xiong ◽  
Pingle Liu ◽  
...  
Keyword(s):  
Mild Condition ◽  
Major Product ◽  
High Yield ◽  
Vanadium Catalysts ◽  
Catalytic Amination ◽  
One Step ◽  
First Time

This is the first time to synthesize naphthylamine from one-step naphthalene amination by vanadium catalysts with high yield under mild condition. It could obtain ∼70% yield of naphthylamine, with major product of valuable 1,5-diaminonaphthalene.

Synthesis of Casein Related Peptides and Phosphopeptides. XIV. Solid Phase Synthesis of Glu-Ser(P)-Leu Through the Use of Protected Boc-Ser(PO3R2)-OH Derivatives

1991 ◽  
Vol 44 (6) ◽  
pp. 771 ◽  
Author(s):  
JW Perich ◽  
RM Valerio ◽  
PF Alewood ◽  
RB Johns
Keyword(s):  
High Pressure ◽  
Peptide Synthesis ◽  
Solid Phase ◽  
Phenyl Group ◽  
High Yield ◽  
Palladium Acetate ◽  
Phase Method ◽  
Phenyl Phosphate ◽  
One Step ◽  
The One

A solid phase method is described for the synthesis of O- phosphoseryl-containing peptides by the use of polystyrene resin (Merrifield) as the peptide support and protected Boc-Ser(PO3R2)-OH derivatives for the incorporation of the phosphorylated seryl residue. The viability of this solid phase approach was demonstrated by the synthesis of HBr.H-Glu-Ser (PO3Et2)-Leu-OH in high yield by the use of Bo -Ser(PO3Et2)-OH in peptide synthesis and subsequent use of HBr/CF3CO2H for cleavage of the Ser(PO3Et2)-containing tripeptide from the resin support. Similarly, the dipeptide, CF3CO2H.H-Ser(P)- Leu -OH, was prepared in high yield by using Boc -Ser(PO3But2)-OH in peptide synthesis followed by the one-step deprotection of the Ser(PO3But2)- dipeptide resin by treatment with HBr/CF3CO2H (90 min). Alternatively, the O-phosphoseryl tripeptide , CF3CO2H.H-Glu-Ser(P)- Leu -OH was prepared by using either Ppoc -Ser(PO3Bzl2)-OH or Boc-Ser(PO3Ph2)-OH in peptide synthesis. The one-step deprotection of the Ser(PO3Bzl2)-containing tripeptide and cleavage of the peptide from the resin support was effected by high-pressure hydrogenolysis (palladium acetate). In the case of phenyl phosphate protection, the Ser(PO3Ph2)-containing peptide was cleaved from the resin support by high-pressure hydrogenolysis (palladium acetate) followed by cleavage of the phenyl phosphate groups by platinum-mediated hydrogenolysis (1.0 equiv. PtO2/phenyl group) in 50% CF3CO2H/AcOH.

scholarly journals Polydentate Schiff Base Ligands and Their La(III) Complexes: Synthesis, Characterization, Antibacterial, Thermal, and Electrochemical Properties

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Ali E. Şabik ◽  
Muharrem Karabörk ◽  
Gökhan Ceyhan ◽  
Mehmet Tümer ◽  
Metin Dığrak
Keyword(s):  
Antimicrobial Activity ◽  
Schiff Base ◽  
Electrochemical Properties ◽  
Antimicrobial Activities ◽  
Nitrogen Atmosphere ◽  
Spectroscopic Methods ◽  
Schiff Base Ligands ◽  
One Step ◽  
The One ◽  
Reversible Transfer

We synthesized the Schiff base ligands H2L1–H2L4 and their La(III) complexes and characterized them by the analytical and spectroscopic methods. We investigated their electrochemical and antimicrobial activity properties. The electrochemical properties of the ligands H2L1–H2L4 and their La(III) complexes were studied at the different scan rates (100 and 200 mV), different pH ranges (), and in the different solvents. The electrooxidation of the Schiff base ligands involves a reversible transfer of two electrons and two protons in solutions of pH up to 5.5, in agreement with the one-step two-electron mechanism. In solutions of pH higher than 5.5, the process of electrooxidation reaction of the Schiff base ligands and their La(III) complexes follows an ECi mechanism. The antimicrobial activities of the ligands and their complexes were studied. The thermal properties of the metal complexes were studied under nitrogen atmosphere in the range of temperature 20–1000°C.

scholarly journals [3 + 2] versus [2 + 2] Addition: A Density Functional Theory Study on the Mechanistic Aspects of Transition Metal-Assisted Formation of 1,2-Dinitrosoalkanes

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Ernest Opoku ◽  
Richard Tia ◽  
Evans Adei
Keyword(s):  
Transition Metal ◽  
Density Functional ◽  
Basis Set ◽  
Functional Theory ◽  
Activation Barriers ◽  
One Step ◽  
The One ◽  
Electron Donating Groups ◽  
Very High ◽  
Addition Pathway

The pathways for the transition metal-assisted formation of 1,2-dinitrosoalkane complexes of cobalt and its congeners, have been studied using DFT/M06 with theLACVP*basis set. The activation barriers for the one-step [3 + 2] addition pathway for the formation of 1,2-dinitrosoalkanes, proposed by Bergman and Becker, are generally low compared to the activation barriers for the [2 + 2] addition to form an intermediate, which is the first of the two-step pathway proposed by Rappé and Upton, which are very high. The barriers of the rearrangement of the Rappé intermediates to the final products by reductive elimination involving the second metal-nitrogenπ-bond are also very high. The reactions of the Co complexes have lower activation barriers than Rh and Ir complexes. The barriers of the reactions involving olefins with electron-donating groups are generally lower compared to the reactions of the parent (unsubstituted) ethylene while the activation barriers for reactions of olefins with electron-withdrawing groups are generally higher compared to the parent (unsubstituted) ethylene. The one-step [3 + 2] pathway remains the most favoured irrespective of the metal centre or the nature of the olefin. The mechanism of the reaction is therefore settled in favour of the [3 + 2] addition pathway.

Mechanical Behavior of Aged Ti-15V-3Cr-3Sn-3Al Alloy

2013 ◽  
Vol 378 ◽  
pp. 82-86
Author(s):  
Ying Kai Chou ◽  
Leu Wen Tsay ◽  
Ying Chiao Wang ◽  
Chun Chen
Keyword(s):  
Tensile Strength ◽  
Mechanical Behavior ◽  
Aging Treatment ◽  
The Other ◽  
Second Step ◽  
Minor Effect ◽  
One Step ◽  
Notched Tensile Strength ◽  
The One ◽  
A Minor

The effect of aging treatments on the mechanical behavior of Ti-15V-3Cr-3Sn-3Al (Ti153) alloy was evaluated in the present study. Properties of the two-step aged specimens were also compared with those of the one-step aged specimens. The second aging treatment, which was performed at 426o°C for 24 h, apparently raised the tensile strength at the expense of the notched tensile strength for the specimens previously aged at 426°C or below. On the other hand, the second-step aging had a minor effect on further hardening of the specimens prior to aging at 538°C and 593°C. In general, theJ-integral value (fracture toughness) had the same trend as that of the notch brittleness of the specimens. Overall, the specimens subjected to the two-step aging treatment did not show any advantage over the specimens subject to one-step aging treatment.

Highly γ-Regioselective 1,2-Addition of α,β-Unsaturated Oxime Ethers with Allylzinc Bromides: A Straightforward Approach for the Synthesis of Homoallylic Amines

Synthesis ◽  
2019 ◽  
Vol 51 (19) ◽  
pp. 3736-3746
Author(s):  
Bo Yang ◽  
Songlin Zhang
Keyword(s):  
Addition Reaction ◽  
Bond Formation ◽  
High Yield ◽  
Carbon Bond ◽  
Carbon Carbon Bond ◽  
Homoallylic Amines ◽  
One Step ◽  
The One ◽  
Straightforward Approach

A highly regioselective reaction between allylzinc bromide reagents and α,β-unsaturated oxime ethers for the one-step synthesis of the homoallylic amines is reported. This process is a regioselective 1,2-addition reaction providing a new γ-position with carbon–carbon bond formation. Furthermore, the reaction substrates are widely applicable and can be produced in a high yield.

Cross-linked enzyme aggregates (CLEA®s): stable and recyclable biocatalysts

2007 ◽  
Vol 35 (6) ◽  
pp. 1583-1587 ◽  
Author(s):  
R.A. Sheldon
Keyword(s):  
Mandelic Acid ◽  
Enantiomeric Purity ◽  
Galactose Oxidase ◽  
High Yield ◽  
One Pot ◽  
Nitrile Hydratases ◽  
Recyclable Catalysts ◽  
One Step ◽  
Enzyme Molecules ◽  
The One

The key to obtaining an optimum performance of an enzyme is often a question of devising an effective method for its immobilization. In the present review, we describe a novel, versatile and effective methodology for enzyme immobilization as CLEAs (cross-linked enzyme aggregates). The method is exquisitely simple (involving precipitation of the enzyme from aqueous buffer followed by cross-linking of the resulting physical aggregates of enzyme molecules) and amenable to rapid optimization. We have shown it to be applicable to a wide variety of enzymes, including, in addition to a wide variety of hydrolases, lyases, e.g. nitrile hydratases and oxynitrilases, and oxidoreductases such as laccase and galactose oxidase. CLEAs are stable, recyclable catalysts exhibiting high catalyst productivities. Because the methodology is essentially a combination of purification and immobilization into one step, the enzyme does not need to be of high purity. The technique is also applicable to the preparation of combi-CLEAs, containing two or more enzymes, for use in one-pot, multistep syntheses, e.g. an oxynitrilase/nitrilase combi-CLEA for the one-pot conversion of benzaldehyde into (S)-mandelic acid, in high yield and enantiomeric purity.

scholarly journals Green synthesis of 3-(1-naphthyl), 4-methyl-3-(1-naphthyl) coumarins and 3-phenylcoumarins using dual-frequency ultrasonication

2020 ◽  
Vol 9 (1) ◽  
pp. 399-404
Author(s):  
Neeraj Vashisth ◽  
Satya Parkash Sharma ◽  
Surender Kumar ◽  
Aruna Yadav
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Green Synthesis ◽  
High Yield ◽  
Dual Frequency ◽  
Ultrasonic Bath ◽  
Magnetic Resonance Data ◽  
Resonance Data ◽  
One Step ◽  
Very High

AbstractGreen synthesis of 3-(1-naphthyl), 4-methyl-3-(1-naphthyl) coumarins and 3-phenylcoumarins has been carried out in one step by reacting 2-hydroxybenzaldehydes and 2-hydroxyacetophenones with 1-naphthylacetic anhydride and phenylacetic anhydride, respectively, using dual-frequency ultrasonication, i.e. ultrasonic bath of 40 kHz and probe of 20 kHz. The compounds were obtained in very high yield (80–90%) and their structures were confirmed by infrared and nuclear magnetic resonance data.

Polyhedral Monocarbaborane Chemistry. A Review of Recent Developments Among C-Aryl Monocarbaborane Systems

2002 ◽  
Vol 67 (7) ◽  
pp. 869-912 ◽  
Author(s):  
Andreas Franken ◽  
Colin A. Kilner ◽  
Mark Thornton-Pett ◽  
John D. Kennedy
Keyword(s):  
Aromatic Aldehydes ◽  
High Yield ◽  
Second Step ◽  
Coupling Reactions ◽  
Recent Developments ◽  
One Step ◽  
Alternative Routes ◽  
Interesting Species

The Brellochs Reactions, of nido-B10H14 with aromatic aldehydes to give [6-Ar-nido-6-CB9H11]- anions in high yield, now permits excellent entries into C-aryl monocarbaborane chemistry, which is reviewed. From [6-Ar-nido-6-CB9H11]-, one-step cluster-closure, cluster-Aufbau, or cluster-dismantling reactions yield [1-Ph-closo-1-CB11H11]-, [7-Ph-nido-7-CB10H12]-, [1-Ph-closo-1-CB9H9]-, [2-Ph-closo-2-CB9H9]-, [4-closo-4-PhCB8H8]- and [6-Ph-arachno-6-CB8H13]. Second-step reactions involving these products yield [2-Ph-closo-2-CB10H10]-, [6-Ph-nido-6-CB8H11], [1-Ph-closo-1-CB7H7]- and [4-Ph-closo-4-CB8H8]-, as well as alternative routes to [1-Ph-closo-1-CB11H11]- and [1-Ph-closo-1-CB9H9]-. This readier access to this extensive suite of C-aryl monocarbaboranes permits a readier examination of their derivative chemistry. Monohalogenated and poly-halogenated species [1-Ph-closo-1-CB9H9-nXn]- and [1-Ph-closo-1-CB11H11-nXn]- have been formed as well as (SMe2)-substituted {CB11} and {CB10} systems. Coupling reactions with para-substituted [XC6H4CB11H10X]- systems give rod-like anions, and with poly-iodinated [PhCB11H5I6]- and [PhCB9H4I5]- give the globular [PhCB11H5Ar5I]- and [PhCB9H4Ar4I]- anions. Additional interesting species include [PhCB11H10CH=CHCH3]-, [PhCB11H10SMe(CH2)4OH]- and [PhCB9H8-6-OH]-. A review with 49 references.

One-Step Synthesis of Water-Soluble Fluorescent Carbon Dots

2015 ◽  
Vol 815 ◽  
pp. 434-439
Author(s):  
Fan Li ◽  
Chang Jun Liu ◽  
Jian Yang ◽  
Feng Tian ◽  
Rui Xin Li ◽  
...  
Keyword(s):  
Carbon Dots ◽  
Heating Temperature ◽  
Nitrogen Atmosphere ◽  
Water Soluble ◽  
Ammonium Citrate ◽  
High Yield ◽  
Transmission Electron ◽  
Relative Quantum ◽  
One Step ◽  
Fluorescent Carbon Dots

Water-soluble carbon dots (CDs) with high yield were synthesized by a facile, one-step incomplete pyrolytic route under nitrogen atmosphere or air using ammonium citrate as carbon source. Photoluminescence (PL) spectrum, Fourier transform infrared (FTIR) absorption and high-resolution transmission electron microscopy (HRTEM) were used to determine the characteristics of the CDs. Though CDs could be prepared from 150 oC to 400 oC, the highest yield of CDs (17.5%) was achieved at the heating temperature of 150 oC in air, so did the relative quantum yield. The as-prepared CDs showed excellent biocompatibility and had been tentatively used in cell imaging.

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