• Journal of the Korean Crystal Growth and Crystal Technology
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• v.14 no.1
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• pp.12-16
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• 2004

In this study, we have investigated the development of the crystal growth stability and reproducibility for large and high-quality DAST. DAST crystal were grown from a saturated methanol solution by a slow cooling method and DAST was synthesized by the condensation of 4-methyl-n-methyl pyridinum tosylate, which was prepared from 4-pocoline and methyl toluenesulponate and 4-N-dimethyl amino-bezaldehyde in the presence of piperidine. We had synthesized DAST crystals in dry Argon atmosphere in order to avoid the formation of hydride organge co-crystals, DAST$.$$H_2O$. Since DAST molecules crystallize in a humid atmosphere, crystal structure become centrosymmetric, and then second order NLO (nonlinear optical) properties would be disappeared. We fixed the growth orientation of DAST crystal (001) surface. The crystal growth was proceeded at a cooling rate of $H_2O$/day and the cooling period is for 4 days. The dimensions of seed crystal was $2.5\times 3.6\times0.4\textrm{mm}^3$ and we have obtained a DAST crystal with the dimension of $10\times 10.5\times3.0\textrm{mm}^3$. The color of grown DAST crystal is red and it's surface appears to be metallic green.

• Journal of the Korean Chemical Society
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• v.53 no.3
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• pp.308-324
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• 2009

The present work is devoted to study the interaction of $\beta$-aroylacrylic acid derivative (3) with malononitrile in (DMF) in the presence of piperidine and/or ammonium acetate, then using the formed compounds as starting materials for synthesizing fused and isolated heterocyclic systems. It has been established that the $\beta$-aroylacrylic acid (3) reacts with malononitrile in (DMF) in the presence of piperidine as a catalyst with the formation of 4H-pyran derivative (4). By changing the catalyst into ammonium acetate, pyridine derivative (5) has been obtained. Also the N-maleamic acid derivatives (19) and (27) have been synthesized via the interaction of (4) and (5) with maleic anhydride. The purpose of this step is to study the behavior of the formed maleamic acid derivatives – as analogies of $\beta$-aroylacrylic acids – towards different active methylene compounds under Michael addition reaction.

• Journal of the Korean Chemical Society
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• v.36 no.2
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• pp.287-292
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• 1992

The rate constants of the nucleophilic addition reaction of amines (piperidine and diethylamine) to phenylvinylketone in various solvents have been determined by UV spectrophotometry at $25^{\circ}C$. On the basis of the high sensitivity of the rate to the polarity of the medium, it may be concluded that the reaction intermediate has zwitterionic character. The effect of the solvents on the rate of the bimolecular nucleophilic addition reaction is described well by the Kirkwood equation: The transition state of the reaction has a cyclic structure formed through an intramolecular hydrogen bond. The addition reaction of primary and secondary amines to phenylvinylketone in all solvents take place considerably faster than that of tertiary amine and this results also can be explained by the intermediate products in the reaction have a cyclic structure formed through an intramolecular hydrogen bond for the primary and secondary amines but not for the tertiary amine.

• Applied Chemistry for Engineering
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• v.34 no.1
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• pp.57-63
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• 2023

In this study, an organic-inorganic hybrid composite of Abaca nanocellulose and titanium dioxide was prepared. Abaca nanocellulose was prepared by oxidizing Abaca cellulose using TEMPO (2,2,6,6-tetramethyl-piperidine-1-oxyl) as a catalyst. Titanium dioxide nanoparticles were prepared by the sol-gel method, and a composite was prepared by hybridizing them with nanocellulose. As a result of comparing the properties of the composite and its physical properties according to the change in manufacturing pH, the effect of pH was very large when combining nanocellulose and titanium dioxide, and the optimal bonding performance was shown at pH 8 in this experimental condition. In addition, the prepared composite showed photocatalytic properties, and the higher the content of titanium dioxide, the higher the hydrophilicity of the composite according to UV light irradiation.

• Biomolecules & Therapeutics
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• v.30 no.2
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• pp.191-202
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• 2022

Tetrazoles were designed and synthesized as potential inhibitors of triple monoamine neurotransmitters (dopamine, norepinephrine, serotonin) reuptake based on the functional and docking simulation of compound 6 which were performed in a previous study. The compound structure consisted of a tetrazole-linker (n)-piperidine/piperazine-spacer (m)-phenyl ring, with tetrazole attached to two phenyl rings (R1 and R2). Altering the carbon number in the linker (n) from 3 to 4 and in the spacer (m) from 0 to 1 increased the potency of serotonin reuptake inhibition. Depending on the nature of piperidine/piperazine, the substituents at R1 and R2 exerted various effects in determining their inhibitory effects on monoamine reuptake. Docking study showed that the selectivity of tetrazole for different transporters was determined based on multiple interactions with various residues on transporters, including hydrophobic residues on transmembrane domains 1, 3, 6, and 8. Co-expression of dopamine transporter, which lowers dopamine concentration in the biophase by uptaking dopamine into the cells, inhibited the dopamine-induced endoctytosis of dopamine D₂ receptor. When tested for compound 40 and 56, compound 40 which has more potent inhibitory activity on dopamine reuptake more strongly disinhibited the inhibitory activity of dopamine transporter on the endocytosis of dopamine D₂ receptor. Overall, we identified candidate inhibitors of triple monoamine neurotransmitter reuptake and provided a theoretical background for identifying such neurotransmitter modifiers for developing novel therapeutic agents of various neuropsychiatric disorders.

• Membrane Journal
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• v.33 no.6
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• pp.416-426
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• 2023

In this study, hindered amine-grafted graphene oxide (HA-GO) with antioxidant properties was prepared and incorporated into Nafion-based composite membranes as an effective filler material for polymer electrolyte membrane fuel cell applications. HA-GO was synthesized via a ring-opening reaction between amine groups in 4-amino-2, 2, 6, 6-tetramethyl piperidine and epoxy groups on the surface of GO. Nafion-based composite membranes containing different weight contents of HA-GO were fabricated to compare the polymer electrolyte membrane properties with those of the pure Nafion membrane. The composite membranes with HA-GO were found to have better mechanical properties, chemical stability, and proton conductivity than the pure Nafion membrane. In particular, the conductivity retention behavior confirmed by the decrease in proton conductivity after Fenton's test of the composite membranes was better than that of the pure Nafion membrane due to the incorporation of HA-GO with effective antioxidant properties.

• Bulletin of the Korean Chemical Society
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• v.34 no.6
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• pp.1848-1852
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• 2013

6,7-Dimethoxy-2-methyl-3-(4-nitrophenoxy)quinoline was synthesized by Friedl$\ddot{a}$nder's cyclization reaction. Different bases and solvents were tested in order to optimize the reaction conditions. The highest yields were obtained using piperidine in refluxing ethanol. Further reactions were carried out in order to prepare different diarylamide and diarylurea derivatives in moderate to high yields in order to examine their anticancer activities.

• Journal of Korean Society for Atmospheric Environment
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• v.3 no.1
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• pp.1-12
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• 1987

A series of supported sulfided Ni-W/$\gamma-Al_2O_3$ and Co-W/$\gamma-Al_2O_3$ catalysts with different nickel and cobalt contents were studied in the hydrodenitrogenation of pyridine dissolved in n-heptane. The ranges of experimental conditions were at the temperatures between 453 and 753 K, and the pressures between 30 and 50 Bar. The catalytic activities with different nickel and cobalt contents were shown to be maximum at Ni/Ni+W = 0.2 - 0.3, Co/Co+W = 0.3 - 0.4. Pyridine conversion increased with pressure and temperature and the step of piperidine formation was found to be irreversible. The reaction orders in Ni-W/$\gamma-Al_2O_3$ and Co-W/$\gamma-Al_2O_3$ catalysts were the first with respect to pyridine and reaction rate constants decreased with increase of initial pyridine concentration and their activation energies were 12.98 and 9.23 kcal/mol, respectively.

• Macromolecular Research
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• v.8 no.5
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• pp.209-214
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• 2000

Polyenaminonitriles containing cycloaliphatic and aliphatic units were prepared by interfacial or solution polymerization reaction of p-bis(1-chloro-2,2-dicyanovinyl) benzene (1) with 4-aminobenzyl-amine, 1-(2-aminoethyl)piperazine, 2-(aminomethyl)pyrrolidine and 4-(aminomethyl)piperidine. The chemical structure of the polymers was confirmed through a syntheses of the model compound. The resulting polymers possessed inherent viscosities of 0.29∼0.62 dL/g and they were easily soluble in polar aprotic solvents and common organic solvents. Thermal properties of the polymers such as curability and stability were studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and infrared spectroscopy. The polymers exhibited a large exotherm in DSC analyses and underwent a curing reaction around 340-370$\^{C}$ to form insoluble materials. The polymers showed 70-80% residual weight at 600 $\^{C}$ under nitrogen.

• Journal of the Korean Chemical Society
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• v.12 no.1
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• pp.35-38
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• 1968

Radio iodination of various aromatic derivatives (aniline, toluene, iodobenzene, acetanilide, benzene, benzoic acid) were achieved at low temperature by a chloroamine-T procedures in presence of polar solvent(dioxane). Organic base (piperidine) was used as the catalyst. Iodine replacement reaction had occured on the aromatic or alicyclic ring by this reaction, and the kind and ratio of iodinated products were proved to be different from those of usual iodide reaction in organic solvent at low temperature. The reactivity of various aromatic or alicyclic compounds towards the present iodination system was evaluated and the scope and limitation of the present procedures in the preparation of radio pharmaceuticals were discussed.