• Applied Chemistry for Engineering
• /
• v.7 no.4
• /
• pp.623-632
• /
• 1996

The reactivity ratios, melting temperature and polymer morphology in propylene/butene-1 and propylene/hexene-1 copolymerization reactions were studied by examining comonomer compositions of resulting polymers. The catalysts used here are different in their supports which are silica(catalyst I) and magnesium(catalyst II). As the content of comonomer(butene-1 and hexene-1) increased in the copolymer, the melting temperature of the copolymer decreased. The morphology of polymer was amorphous in the range of comonomer(butene-1) composition over 40% in the propylene/butene-1 copolymerization and comonomer(hexene-1) composition over 80% in the propylene/hexene-1 copolymerization. The reactivity ratios were obtained by the Fineman-Ross and Kelen-$T{\ddot{u}}d{\tilde{o}}s$ methods.

• Polymer(Korea)
• /
• v.35 no.6
• /
• pp.505-512
• /
• 2011

Effects of structural features of 4 dinuclear constrained geometry catalysts having paraxylene derivative bridge (DCGC) on copolymerization of ethylene and 1-hexene were investigated. The bridges of three catalysts have para-xylene backbone with a different substituent at benzene ring. The substituents were hydrogen (Catalyst 1), isopropyl (Catalyst 2), n-hexyl (Catalyst 3) and 1-octyl (Catalyst 4). It was found that Catalyst 1 having hydrogen as a substituent exhibited the greatest activity among the four dinuclear CGCs. On the other hand, Catalyst 2 containing isopropyl as a substituent showed the smallest activity. Very interestingly, Catalyst 2 was able to produce about 6 times higher molecular weight polymer than Catalyst 3 and 4. Catalyst 3 and 4 having a long alkyl chain substituent revealed the biggest comonomer response to generate polyethylene copolymer containing more than 40% 1-hexene contents. These results suggest that the control of the substituent of para-xylene bridge of dinuclear CGC can provide a proper method to adjust the microstructure of polyethylene copolymers.

• The Korean Journal of Pesticide Science
• /
• v.17 no.2
• /
• pp.140-143
• /
• 2013

We investigated optimal condition for synthesis of (E)-2-hexenyl (E)-2-hexenoate (1) and (E)-2-hexenyl (Z)-3-hexenoate (2), the pheromone components of Riptortus pedestris, by Steglich esterification. The reaction with 1.1-1.5 equivalent of dicyclohexylcarbodiimide (DCC), 1.5-2.0 equivalent of (E)-2-hexenol, and 0.1 equivalent 4-dimethylaminopyrinde (DMAP) to (E)-2-hexenoic acid in toluene or (Z)-3-hexenoic acid in dichloromethane led 1 and 2 in 76-78% and 87-91% yield, respectively.

• Journal of the Korean Chemical Society
• /
• v.34 no.2
• /
• pp.130-135
• /
• 1990

The title compound (C13H17NO2S) is monoclinic, space group P21/a, with a = 13.756 (3), b = 9.310(4), c = 21.305(3) $\AA$, $\beta$ = 95.0。, Z = 8, V = 2718.11 $\AA$3, Dc = 1.23$g·{\cdot}cm-3$, (Mo k$\alpha$) = 0.71069$\AA$,$\mu$ = 2.18 cm-1, F(000) = 1071.86, T = 298, R = 0.085 for 2935 unique observed reflections with I >2.0$\sigma$(I). The structure was solved by direct methods. The C-H bond lengths and the methyl groups are fixed and refined as their ideal geometry by allowing to ride on the parent atoms. Both molecules A and B have almost same structures except for two terminal ethyl groups. The ethylene-like skeleton including the nitro group in one molecule is nearly perpendicular to the plane of the methylbenzene group and two ethyl groups form a cis-type structure which has the dfferent orientations between two molecules; in the molecule A, two terminal methyl groups being the opposite directional arrangement against the plane of its skeleton, while in the B, with the same directional structure from its plane. The molecules in the crystal are packed together by non-bonded van der Waals forces.

• Journal of the Korean Chemical Society
• /
• v.23 no.5
• /
• pp.325-328
• /
• 1979

trans-1,2-Bispyrazylethylene (BPE) undergoes photoaddition reaction to tetramthylethylene (TME) which appears to involve radical intermediates under conditions where the corresponding hydrocarbons are unreactive. This photoaddition reaction involves abstraction of an allylic hydrogen atom of TME by $^1(n,\;{\pi}^*)$ states of BPE having radical character. The major photoadduct is isolated by column chromatography and fractional vacuum sublimation and characterized to be 2,3-dimetyl-5,6-bispyrazyl-2-hexene.

• Journal of Life Science
• /
• v.33 no.1
• /
• pp.43-49
• /
• 2023

Houttuynia cordata belongs to the Saururacease family and its leaves, stems, and roots have been used as oriental medicines to treat pneumonia, acute or chronic bronchitis, enteritis, and abscesses and to remove extravasated blood. Recently, the antioxidant, anti-inflammation, antibacterial, and anti-proliferation activities and protection abilities of H. cordata against liver and neuron cell damage have been reported. In this study, ethanol extract and its solvent fractions (fractions of hexane, ethyl acetate, butanol, and water residue) were prepared, and their antithrombosis, antidiabetes, antioxidant, and hemolysis activities were evaluated. The ethyl-acetate fraction of H. cordata (EF-HC) showed the highest polyphenol and flavonoids contents among the fractions and exhibited strong antithrombosis and antioxidant activities. The EF-HC at 5 mg/ml showed 2.09-folds of thrombin time, 2.19-folds of prothrombin time, and 1.69-folds of activated partial thromboplastin time compared to the their solvent control and 30.9, 19.9, and 49.6 ㎍/ml of RC₅₀ against DPPH, ABTS, and nitrite radicals, respectively. Furthermore, the EF-HC did not show any hemolytic activity up to 1 mg/ml, whereas the hexane fraction of H. cordata showed 55% hemolysis at 1 mg/ml. This is the first report of the antithrombosis activity of H. cordata. Our results suggest that quercitirin, hyperoside, orientin, and isoquercitrin in EF-HC are related to its antithrombosis and antioxidant activities and that the EF-HC could be developed as a promising antithrombosis agent.

• Elastomers and Composites
• /
• v.48 no.1
• /
• pp.85-91
• /
• 2013

In this study, we synthesized a terpolymer consisting of ethylene, 1-hexene, and styrenic monomer using a metallocene catalyst and cocatalyst ststem. The styrenic monomers empolyed as the third monomer were styrene, p-methylstyrene, and 4-tert-butylstyrene. The structure and composition of the terpolymers were characterized using $^{13}C$ NMR and $^1H$ NMR. Catalytic activity, polymer yield, molecular weight and molecular weight distribution of the terpolymers were analyzed. We also determined the glass transition temperature(Tg), crystallinity and thermal properties of the terpolymers by DMA, WAXS and TGA.

• Polymer(Korea)
• /
• v.39 no.2
• /
• pp.346-352
• /
• 2015

Polyalphaolefin (PAO) is a synthetic lubricant that is superior to mineral-based lubricants in the terms of physical and chemical characteristics such as low pour point, high viscosity index (VI), and thermal and oxidation stability. Several kinds of PAOs have been synthesized by using 1-pentene, 1-hexene, 1-octene, or 1-dodecene as monomer with three kinds of aluminum-based Lewis acid catalysts via cationic polymerization. The control of the catalytic performance and physical properties of PAO such like molecular weight, kinematic viscosity, pour point, and viscosity index was done by changing polymerization parameters. The alkyl aluminum halide-based catalysts show better catalytic activity than that of the conventional $AlCl_3$ catalyst. The microstructure of PAO was investigated by means of TOF-MS (time of flightmass spectroscopy) analysis in order to elucidate the correlation between the performances of the lubricant (VI, pour point) and the molecular structure of PAO. The VI of PAO increases with increases in the carbon number of ${\alpha}$-olefin. In other words, the performances of PAO as a lubricant strongly depended on the branch length of PAO.

• Journal of the Korean Chemical Society
• /
• v.48 no.2
• /
• pp.156-160
• /
• 2004

The extraction rates of plasticizer of LPG high pressure rubber are studied. Submerging solvents are composed of propane, n-butane, n-pentane, n-hexane, n-heptane, propylene, 1,3-butadiene, 1-pentene, 1-hexene, ethanethiol, t-butanethiol, dimethyl sulfide, methyl ethyl sulfide. The relationship between the extraction rate of plasticizer and the descriptors of submerging solvent by using multiple linear regression is as follows; PE(wt%) = 7.5193 - 0.58500Carbon${\sharp}$ + 2.3294DB + 2364SH, (N = 13, F = 24.135, R$^2$ = 0.8894, R$_{adj}^2$ = 0.8526, Variance = 7.588) Plasticizer is well extracted by LPG composed of the high vapour pressure and polarity compounds. The mass of extracted plasticizer becomes increasing in proportion to the contents of thiol sulfur compound and unsaturated hydrocarbon such as propylene and 1,3-butadiene in LPG. While the heavier hydrocarbons are, the less the quantities of plasticizer extracted from rubber are.

• Journal of the Korean Chemical Society
• /
• v.22 no.1
• /
• pp.45-51
• /
• 1978

The luminescence of N-methyllutidone is studied in ethanol matrix at $77^{\circ}C$K. No fluorescence is observed but a strong phosphorescence with the quantum yield of 0.1 and the lifetime of 0.2 sec is recorded. An unusually high triplet energy of 85.1 kcal/mole is determined for the compound from the O-O band of phosphorescence. The cis ${\leftrightarrow}$ trans photoisomerization of high triplet energy olefins such as 2-hexene and trans-1,4-dichlorobutene-2 is efficiently sensitized by N-methyllutidone substantiating the high triplet energy of the compound. The negative polarization of O-O band reveals the emitting triplet state to be $({\pi},{\pi}^*)^3$ state. Alkaline metal salts such as lithium chloride enhances the phosphorescence intensity through cation-N-methyllutidone coordination widening the gap between $({\pi},{\pi}^*)^3$and $(n,{\pi}^*)^3$ states.