• Journal of the Korean Chemical Society
• /
• v.34 no.5
• /
• pp.490-497
• /
• 1990

Two synthetic routes for the 1,4-diboracyclohexene-2 ring 8 have been developed. Method i) starts with 1,2-bis(dichloroaluminyl)ethane, in which the AlCl$_2$ group is replaced by BCl$_2$. Exchange of the chlorine with BI$_3$ in 1,2-bis-(dichloroboryl)ethane yields the corresponding iodo compound, which reacts with the alkynes to heterocycles 8a, b in good yield. In method ii) B$_2$Cl$_4$ is added to alkenes, replacement of chlorine with BI$_3$ yields the bis(diiodoboryl)ethane derivatives which undergo redox reactions with alkynes to give 8c, d. The diiodo derivative 8a forms the pyridine adduct 9a, and reacts with ether to give the ethoxy derivative 8f. 8a-d react with AlMe$_3$ to yield the corresponding dimethyl derivatives 8g-j, which give unstable radical anions when treated with potassium in THF. The ESR parameters are reported. In electrochemical experiments irreversible reductions of 8g-j are observed. 8g-j react with (C$_5$H$_5$)Co(C$_2$H$_4$)$_2$ to give the intermediate 16 VE complexes (C$_5$H$_5$)Co(8), in which C-H activation occurs with formation of the corresponding red 1,4-diboracyclohexadiene complexes 10. The X-ray structure analyses of 10h and 10j are reported.

• Bulletin of the Korean Chemical Society
• /
• v.21 no.3
• /
• pp.291-294
• /
• 2000

The bulk photopolymerization of methyl methacrylate(MMA) with bis(silane)s such as 1,4-$C_6H_4(SiH_3)_2$ (1) and 1,4-$C_6H_4(SiH_2Me)_2$ (2) was performed to produce poly(MMA)s possessing the corresponding bis(silyl) moiety as an end group. For the bis(silane)s, while the polymerizaiton yields and the polymer molecular weights decreased, the TGA residue yields and the relative intensities of Si-H IR stretching bands increased as the relative bis(silane) concentration over MMA increased. The polymerizaion yield, polymer molecular weight, and TGA residue yield of MMA with 1 were found to be higher than those with 2. The bis(silane)s appears to influence significantly upon the photopolymerization of MMA as both chain initiation and chain transfer agents.

• Journal of the Korean Chemical Society
• /
• v.57 no.5
• /
• pp.612-617
• /
• 2013

The versatile, hitherto unreported 3-(4-(2-phenyldiazenyl)-2-oxo-2H-chromen-3-yl)-3-oxopropanenitrile 3 was prepared by two convenient routes: either by the reaction of ethyl 4-(2-phenyldiazenyl)-2-oxo-2H-chromen-3-carboxylate 2 with acetonitrile in the presence of sodium hydride or by treatment of 4-(2-phenyldiazenyl)-3-(2-bromoacetyl)-2H-chromen-2- one 5 with potassium cyanide. Reaction of 3 with heterocyclic diazonium salts 6, 7, 14 and 17 furnished the corresponding hydrazones 8, 9, 15 and 18. The latter hydrazones underwent intramolecular cyclization into the corresponding pyrazolo[5,1- c]-1,2,4-triazine 10, 1,2,4-triazolo[5,1-c]-1,2,4-triazine 11, 1,2,4-triazino[4,3-b]indazole 16 and imidazo[2,1-c]-1,2,4-triazine 19 derivatives, respectively upon refluxing in pyridine.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1993.11a
• /
• pp.34-35
• /
• 1993

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.27 no.7
• /
• pp.893-900
• /
• 2003

Numerical simulations of freely propagating flames burning stoichiometric C $H_4$/CHC1$_3$/ $O_2$/$N_2$ mixtures are performed at atmospheric pressure in order to understand the effect of the $O_2$ enrichment level and the CHC1$_3$/C $H_4$ molar ratio. A chemical kinetic mechanism is developed, which involves 69 gas-phase species and 379 forward and 364 backward reactions. The calculated flame speeds are compared with the experiments for the flames established at several CHC1$_3$/C $H_4$ molar ratio (R<1), the results of which is in excellent agreement. As a results of the increased $O_2$ enrichment level from 0.21 to 1, the flame speed and the temperature in the burned gas are increased. At high CHC1$_3$/C $H_4$ molar ratio two peak values appear on the $O_2$ consumption rate, which are affected by CC1$_2$＋ $O_2$$_{-}$>C1O+CC1O and H＋ $O_2$$_{-}$>O＋OH.＋OH.

• Journal of the Korean Society of Combustion
• /
• v.5 no.1
• /
• pp.7-18
• /
• 2000

Numerical simulations of counterflow non-premixed $CH_4/C_2HCl_3/Air$ flames added 8%(by volume) C2HCl3 on the fuel side are conducted at atmospheric pressure using a detailed chemical reaction mechanism in order to understand the effect of strain rates. A detailed sensitivity analysis is also performed in order to assess the relative influence of each reaction on the flame established at a strain rate of 200s-1. The structure of flames (i.e., temperature, velocity, and concentration of species) established at both a strain rate of 150s-1 and 300s-1 are investigated. As the strain rate increases, the "flame zone" is restricted to a narrower range and the position of maximum temperature is shifted to the fuel side. The concentrations of major species, H2O, CO, H2, HCl, Cl2, and Cl are decreased with increased strain rate. The reaction involving chlorine, CH4 + Cl $\rightarrow$ CH3 + HCl, instead of the reaction, CH4 + H $\rightarrow$ CH3 + H2 influences the consumption of methane. C2HCl3 + OH $\rightarrow$ CHCl2 + CHOCl and HCl + OH $\rightarrow$ H2O + Cl, are major reactions, through which OH radicals are consumed.

• Bulletin of the Korean Chemical Society
• /
• v.18 no.8
• /
• pp.806-810
• /
• 1997

A series of new hydridocarbonyl osmium(Ⅱ) complexes, OsHCl(CO)(PPh3)(L-L)[L-L=Ph2P(CH2)nPPh2 (n=1 (1), 2 (2), 3 (3), cis-Ph2PCH=CHPPh2 (4), and Fe(η5-C5H4PPh2)2 (5)] has been synthesized from OsHCl(CO)(PPh3)3 and chelating diphosphines. These complexes have been characterized by IR, 1H NMR and elemental analysis. The catalytic activities of these complexes both for the transfer hydrogenation of trans-cinnamaldehyde with 2-propanol as the hydrogen donor, and for the selective hydrogenation of trans-cinnamaldehyde with H2, have been examined. Complexes (1)-(5) were shown to have higher selectivities for the transfer hydrogenation of the C=O bond of aldehyde than for the transfer hydrogenation of the C=C bond of aldehyde. The selectivities for the transfer hydrogenation with 2-propanol as well as for the hydrogenation with H2 have been found to decrease in the order 3 > 5 > 2 > 4 > 1. Complex (3) has shown to possess almost 90% of the selectivity to cinnamyl alcohol for transfer hydrogenation. It is also found that there is a correlation between the ν(CO) of each complex and the hydrogenation, of the C=O bond of trans-cinnamaldehyde. Overall, the selectivities with the complexes (1)-(5) are greater for the transfer hydrogenation with 2-propanol than for the hydrogenation with H2.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.18 no.1
• /
• pp.74-83
• /
• 1985

The primary productivity and chlorophyll a were measured at 3 stations in the western channel of the Korea Strait throughout the year from November 1983 to September 1984. The surface primary productivity in autumn 1983 ranged from 9.24-13.05 mg $C/m^3/h$ and chlorophyll a from $0.66-1.22\;mg/m^3$, and showed the highest value throughout the year. The surface primary productivity in winter 1984 ranged from 0.75-1.77 m $C/m^3/h$ and chlorophyll a from $0.19-0.41\;mg/m^3$. and these values were higher than those in summer. The surface primary productivity in spring 1984 ranged from 3.42-6.68 mg $C/m^3/h$ and chlorophyll a from $0.34-0.64\;mg/m^3$, and these values were lower than those in autumn. The surface primary productivity in summer 1984 ranged from 0.57-0.79 mg $C/m^3/h$ and chlorophyll a from $0.11-0.17\;mg/m^3$, and showed the lowest value throughout the year. The assimilation number of surface phytoplankton populations were relatively high, especially high value in autumn and spring, and low value in winter. The primary productivity and assimilation number were rapidly decreased with the increase of depth.

• Journal of the Korean Chemical Society
• /
• v.53 no.2
• /
• pp.224-228
• /
• 2009

• Journal of Plant Biology
• /
• v.37 no.3
• /
• pp.387-394
• /
• 1994

Effects of environmental factors of light, temperature, nitrogen sources and water stress were analyzed quantitatively on the nodule formation and nitrogen fixation activity of autumn olive plant (Elaeagnu$ umbellala Thunb.) during the seedling growth. Seedlings showed the maximum nitrogenase activity of $72.5\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$ in the early nodulation stage. The relative growth rate and T/R ratio changed from $1.60%{\cdot}d^{-1}$ and 1.12 in the earlier stage to $3.75%{\cdot}d^{-1}$ and 2.31 in the later stage, respectively. light conditions of 20-25, 1015 and 4-6% resulted in decreases of 41, 54 and 71% of the nitrogenase activity, respectively. Nodules incubated in 15, 20, 25 and $30^{\circ}C$ showed the activities of 5.4, 24.7, 51.6 and $58.5\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$ respectively. Pretreatment with low temperature ($15^{\circ}C$) followed incubation at $30^{\circ}C$ attained higher nitrogenase activity ($66.5\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$) than that with higher temperature ($35^{\circ}C$). The oxygen pressure above 16 kPa is necessary for saturation of the nodule activity, but the activity was inhibited severely by physical impact such as the exision or isolation of nodules from the root. The relative activities of early nodules grown in pH 5.5, 6.5 and 8.0 were 89, 100 and 40% and those grown in 1 and 3 mM of $NO_3\;and\;NH_4$ were 6, 1 and 68, 50%, respectively. Watering levels of 20, 50 and 100 mL during the seedling growth resulted in 35, 120 and 8 mg of nodule formation and 33.6, 58.4 and $8.4\;\mu\textrm{M}\;C_2H_4{\cdot}g\;fr\;wt\;nodule^{-1}{\cdot}h^{-1}$ of the nitrogenase activity, respectively. Water stress with 86% decrease of soil water content caused temporary wilting point of leaf and a complete disappearance of nitrogenase activity of nodules, though the water content and transpiration rate in plant were reduced to 90 and 53%, respectively.tively.