• Applied Chemistry for Engineering
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• v.16 no.5
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• pp.705-711
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• 2005

The reaction of lauric acid vinyl ester with n-butanol was established to give lauric acid butyl ester by subtilisin A-catalyzed transesterification in organic media containing nonionic surfactants. Pyridine has been used as an organic solvent since it provides higher yields than other organic solvents. However, because of stench of pyridine, compounds enzymatically synthesized in pyridine may be unsuitable as ingredients for foods and drugs. Hence, in order to select an organic solvent to replace pyridine, sugar esters were synthesized with the protease in various organic media. However, no solvent paralleled pyridine in yields. On the basis of this result, pyridine-based W/O microemulsions containing nonionic surfactants and water were used in enzymatic synthesis of the sugar ester, and when Tween 60, Brij 56, or 1-O-octyl-${\beta}$-D-glucopyranose was used for the W/O microemulsions, the yield was higher.

• Journal of the Korean Chemical Society
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• v.26 no.6
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• pp.378-382
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• 1982

Green crystalline salts of substituted pyridinium oxopentachloromolybdates(V) were obtained from concentrated hydrochloric acid solution of molybdenum(V)-thiocyanate extract. $MoOCl_3(X-py)_2$ (X-py were 4-and 3-cyanopyridine, 2-amino-4-picoline and 4-acetylpyridine) were obtained by reflux of the corresponding substituted pyridinium salts of oxopentachloromolybdates(Ⅴ) in absolute ethanol. ($X-pyH_2$)[$MoOCl_5$]$H_2$O containing the $MoO^{3+}$ group are dissolved and hydrolysed in water but $MoOCl_3(X-py)_2$ are insoluble in water, alcohol and acetone. The complexes are paramagnetic compounds.

• Applied Chemistry for Engineering
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• v.2 no.2
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• pp.138-146
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• 1991

$Pd/SiO_2-Al_2O_3$ catalysts were prepared for the synthesis of pyridine and ${\beta}$-picoline from acrolein and ammonia. The activity of these catalysts decreased considerably by the formation of deposits on catalyst surface during the reaction. TPR study showed that the deposits were formed by the condensation polymerization of acrolein and ammonia. The conversion and production rate of pyridine and ${\beta}$-picoline decreased with the partial pressure of acrolein. The amount of deposits and the regeneration temperature of spent catalysts increased with the partial pressure of acrolein but they were independent of the concentration of ammonia.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.50-56
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• 2006

We investigated the adsorption of benzene and pyridine on $Si(5\;5\;12)-2\times1$ at 80 K by using variable-low temperature scanning tunneling microscopy (STM) and density functional theory (DFT) calculations. The benzene molecule most strongly binds to two adatoms on the D3 and D2 units in a tilted butterfly configuration, which consists of $di-\sigma$ bonds between C atoms and Si adatoms and two C=C double bonds in the benzene molecule Pyridine molecules interact with adatom(s) on the D2 and D3 units through both Si-N dative bonding and $di-\sigma$ bonds. The dative bonding through the lone pair electrons of N atom produces a vertical configuration (pyridine-like), which is more stable than $di-\sigma$ bonds $Di-\sigma$ bonds can be formed either through Si-N1 and Si-C4 or Si-C2 and Si-C5.

• Journal of the Korean Chemical Society
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• v.31 no.5
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• pp.413-418
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• 1987

Rates of the reaction for p-nitro benzyl chloride, benzyl chloride and p-methyl benzyl chloride with pyridine in methanol solvent have been measured by an electric conductivity method at 40$^{\circ}$C and 50$^{\circ}$C under various pressures (1∼2000bar). Pseudo first-order rate constants and second-order rate constants were determined. Rates of these reactions were increased in the order p-NO$_2$ < p-H < p-CH$_3$ and increased with temperature, pressure and concentration of pyridine. From those rate constants, the activation parameters were evaluated. The activation volume and the activation compressibility coefficient are both negative values, but the activation enthalpy is positive and the activation entropy is large negative value. From the evaluation of the ground state and transition state which was resulted from substituents and pressure, it was found that this reaction proceeds through S$_N$2 reaction, and S$_N$2 fashion is slightly disappeared as pressure increases.

• Journal of the Korean Chemical Society
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• v.9 no.3
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• pp.134-141
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• 1965

Crystals of nicotine dihydroiodide, are orthorhombic with space group $p2_12_12_1$.The unit cell of dimensions a=7.61, b=11.01, e=17.27${\AA}$, contains four formula units. The structure has been determined by X-ray diffraction method and has been refined to give the R-index, ${\sum}{\mid}{\mid}F_{\circ}{\mid}-{\mid}F_c{\mid}{\mid}{\div}{\sum}{\mid}F_{\circ}{\mid}$, of 0.16 and 0.14 for $F_{okl}\;and\;F_{hol}$ respectively.The mean lengths of C-C and C-N bonds in pyridine ring are 1.40 and $1.35{\AA}$ and those in pyrolidine ring 1.56 and $1.48{\AA}$ respectively, though accurate measurement of bond length has not been attempted. The six atoms in the pyridine ring are coplanar and on the other hand $C_6,\;C_7,\;C_8$ and $N_2$ atoms in pyrrolidine ring form a plane within accuracy of the analysis, and $C_9$ atom is distant $0.22{\AA}$ out of the plane consist of $C_6,\;C_7,\;C_8$ and $N_2$ aoms. The normals to the two planes form an angle of $94^{\circ}$ with each other. Iodine atom is distant $3.55{\AA}$ from nitrogen atom in pyridine ring and the other iodine atom $3.58{\AA}$ from nitrogen atom in pyrrolidine ring, so that the nitrogen and iodine atoms are firmly linked.It seems that the only forces binding nicotine dihydroiodide molecules together in the crystal are Van der Waals forces.

• Journal of the Korean Chemical Society
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• v.53 no.2
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• pp.133-136
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• 2009

We present calculations for the 4-aminopyrimidine (4AP) – HCl and –HBr complexes. We predict that the charge separated (zwitterionic) form [4AP$H^+-Cl^-$] is not stable, but that [4AP$H^+-Br^-$] is stable enough for experimental detection in gas phase at low temperatures. The latter observation is attributed to smaller dissociation energy of HBr compared with HCl, and to “solvation” of HBr by the amino group in 4AP.

• Journal of the Korean Chemical Society
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• v.32 no.1
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• pp.48-52
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• 1988

Kinetics of the reaction of 2-phenethyl p-bromobenzenesulfonate with substituted pyridines in acetonitrile were investigated by an electric conductivity method at 1-2000 bars and $45{\sim}55{\circ}C$. The rates of these reactions were increased with raising temperatures, pressures and by changing electron-donating substitutents in pyridine. When raising pressure the Hammett reaction parameter $I{\rho}I$ and Bronsted ${\beta}$ values were increased, and isokinetic temperature observed from isokinetic relations hip between ${\Delta}H^{\neq}$ and TEX>${\Delta}S^{\neq}$ was decreased. These results indicate that the $S_N2$ characters were increased with raising pressure.

• Journal of the Korean Chemical Society
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• v.28 no.2
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• pp.143-146
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• 1984

• Journal of the Korean Chemical Society
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• v.27 no.1
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• pp.1-8
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• 1983

Solvent effects on nucleophilic substitution reaction of naphthalene sulfonyl chlorides with pyridine in protic and aprotic solvent have been studied by means of conductometry. Results showed that the rate constants increased with dielectric constants for protic solvents, while they decreased with dielectric constants for aprotic solvents, except for acetonitrile which has a higher dielectric constant but had also greater rate constant. The rate constants were shown to be more susceptible to polarity-polarizability parameter, , than to hydrogen bond donor acidity parameter, ${\alpha}$, indicating that the pulling effect of hydrogen bonding solvent.