• Bulletin of the Korean Chemical Society
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• 제27권10호
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• pp.1685-1688
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• 2006

• Bulletin of the Korean Chemical Society
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• 제35권7호
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• pp.2130-2134
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• 2014

A kinetic study is reported on nucleophilic substitution reactions of 4-nitrophenyl isonicotinate (7) with a series of cyclic secondary amines in MeCN. The plots of $k_{obsd}$ vs. [amine] curve upward for the reactions with weakly basic amines (e.g., morpholine, 1-(2-hydroxyethyl)piperazine, and piperazine) but are linear for those with strongly basic amines (e.g., piperidine and 3-methylpiperidine). The curved plots for the reactions with the weakly basic amines are typical for reactions reported previously to proceed through uncatalyzed and catalyzed routes with two intermediates (e.g., a zwitterionic tetrahedral intermediate $T^{\pm}$ and its deprotonated form $T^-$). In contrast, the linear plots for the reactions with the strongly basic amines indicate that the catalytic route (i.e., the deprotonation process to yield $T^-$ from $T^{\pm}$ by a second amine molecule) is absent. The Br${\o}$nsted-type plots for $Kk_2$ and $Kk_3$ (i.e., the rate constants for the uncatalyzed and catalyzed routes, respectively) exhibit excellent linear correlations with ${\beta}_{nuc}$ = 0.99 and 0.69, respectively. The effect of amine basicity on the reaction mechanism is discussed in detail.

• Bulletin of the Korean Chemical Society
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• 제18권5호
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• pp.523-527
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• 1997

Apparent second-order rate constants (kapp) have been measured spectrophotometrically for the reaction of 2,4-dinitrophenyl benzoate (DNPB) with 6 secondary cyclic amines in H2O containing 20 mole% DMSO at 25.0±0.1 ℃. The Bronsted-type plot (log kapp vs. pKa) shows a break at pKa near 9.1, e.g. two straight lines with βapp values of 0.67 and 0.44 for the low basic (pKa < 9.1) and the highly basic (pKa > 9.1) amines, respectively. Using an estimated k2 value of 3×109 sec-1, all the other microconstants (k1, k-1 and K) involved in the present aminolysis have been calculated. The k value decreases with increasing the basicity of amines while k1 and K values increase with increasing the amine basicity, as expected. Good linear Bronsted-type plots have been obtained for these microconstants of the present aminolysis of DNPB. The magnitudes of the slope of the Bronsted-type plots, k1 and k-1 have been calculated to be 0.43 and - 0.24, respectively, indicating the k-1 step is about two folds less sensitive than the k1 step to the amine basicity. The K value has been calculated to be 0.66, which appears to be much smaller than the one for other aminolyses showing general base catalysis. The small K value has been attributed to the absence of general base catalysis in the present aminolysis of DNPB.

• 대한화학회지
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• 제11권4호
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• pp.126-131
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• 1967

各 種 아민(triethylamine, diethylamine, pyridine, diphenylamine, dimethylaniline)과 各種 Electron Acceptor($CCl_4,\;ICl,\;I_2$)를 Hexane 溶媒 存在下에서 作用시킨 結果 各各 Charge Transfer Complex를 形成하였으나 그 形成能은 아민의 Basicity에 比例하였고 Electron Donor의 Polarity의 差가 클 때에는 다른 形式의 Complex를 形成함을 紫外線 吸收 分光法으로 確認하였다. Complex 形成能과 아민의 Basicity 및 Electron Acceptor의 Polarity의 關係를 論하였다.

• 대한화학회지
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• 제22권5호
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• pp.317-319
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• 1978

여러자리 아민리간드에 대해서 이중심 Huckel법의 계산으로 양성자 첨가과정에서 전자에너지 변화와 전자밀도를 논의 하였다. 계산된 ${\Delta}E_{\sigma}$ 및 $q_N,\;q_H$ 값과 실측치 pKb값으로서 여러자리 아민리간드는 trien > en > gly > dien순으로 안정도가 증가함을 보여주었다.

• Bulletin of the Korean Chemical Society
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• 제19권7호
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• pp.776-779
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• 1998

Second-order rate constants have been measured spectrophotometrically for the addition reaction of a series of alicyclic amines to 3-butyn-2-one to yield their respective enamines at 25.0 'C. The reactivity of the amines increases with increasing the basicity of the amines. However, the Bronsted-type plot obtained exhibits a downward curvature as the basicity of the amines increases, i.e. βnuc decreases from 0.3 for low basic amines (pKa < 9) and to 0.1 for highly basic amines (pKa > 9). Such a curvature in the Bronsted-type plot is clearly indicative of a change in the reaction mechanism or transition state structure. From the corresponding reactions run in D2O, the magnitude of kinetic isotope effect (KIE) has been calculated to be about 0.8 for highly basic amines and 1.21 for weakly basic amines. The difference in the magnitude of KIE also supports a change in the reaction mechanism or transition state structure upon changing the basicity of the amines. Furthermore, the small KIE clearly suggests that H+ transfer is not involved in the rate-determining step, i.e. the addition reaction is considered to proceed via a stepwise mechanism in which the attack of the amines to the acetylene is the rate-determining step. The curvature in the Bronsted-type plot has been attributed to a change in the degree of bond formation between the amine and the acetylene.

• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.132-136
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• 2002

$Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)\;(OTf=CF_3SO_3^-)$ readily reacts with various amines to afford cationic amine complexes $[Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(amine)](OTf)\;(amine=NH_3,\;NHMe_2,\;NHC_4H_8,\;NH_2Ph,\;NH_2(Tol-p))$ in high yields. These complexes have been fully characterized by IR, $^1H-,\;^{19}F{^1H}-,\;and\;^{31}P{^1H}-NMR$ spectroscopy, and elemental analyses. Reaction of $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)$ with acrylonitrile quantitatively produced the ${\pi}$-olefinic complex $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(CH_2=CHCN)](OTf)$ which is only stable in solution in the presence of acrylonitrile. Attempt at isolating this complex in the pure solid state was failed due to partial decomposition into $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)$ The equilibrium constants $(K_{eq}=[Pt(PCP)-(NH_2R)^+][CH_2=CHCN]/[Pt(PCP)(CH_2=CHCN)^+][NH_2R]:\;[Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(CH_2=CHCN)]^++NH_2R{\rightleftarrows}[Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(NH_2R)]^++CH_2=CHCN=Ph,\;p-tolyl)$ were calculated to be 0.28 (for R = Ph) and 3.1 (R = p-tolyl) at $21^{\circ}C$. The relative stability of the ${\sigma}$-donor amine versus the ${\pi}$-olefinic acrylonitrile complex has been found largely dependent upon the amine-basicity $(pK_b)$, implicating that acrylonitrile practically competes with amine in the platinum coordination sphere. On the contrary to the formation of the acrylonitrile complex, no reaction of $Pt(2,6-(Cy_2PCH_2)_2C_6H_3)(OTf)$ with other olefins such as ethylene, styrene and methyl acrylate was observed.

• Korean Chemical Engineering Research
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• 제44권4호
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• pp.417-423
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• 2006

실리카계 메조 물질 MCM-41 지지체 위에 여러 방법으로 aminopropyltrimethoxysilane(APMS)을 표면 기능화 시킨 염기촉매를 제조하였고 표준 염기반응인 Knoevenagel 축합반응을 수행하여 촉매적 활성을 측정하였다. Methyltrimethoxysilane으로 추가 표면처리하거나, APMS를 염소함유 유기실란과 축합하여 2차 아민 형성 후 고정화시킨 MCM-41 촉매(BAPM)를 제조한 결과, MCM-41 표면의 잔류 OH를 제거하고 물과의 수소결합으로 아민 활성점의 기능이 약화되는 것을 억제하여 높은 TON을 얻을 수 있었다. 코팅에 의해 표면에 많은 양의 아민이 고정화된 MCM-41은, 세공 내부의 반응 공간이 줄어들고, 인접한 아민 간의 수소결합으로 인하여 낮은 염기도가 예상되며 촉매 활성도 상대적으로 낮았다. 제조한 촉매 중에는 BAPM이 촉매 활성이 가장 우수하였다.

• 공업화학
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• 제20권6호
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• pp.658-662
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• 2009

본 연구에서는 탄소나노튜브를 KOH를 이용하여 활성화 한 후 이를 아민으로 표면처리한 탄소나노튜브의 이산화탄소 흡착거동에 관하여 고찰하였다. 아민 처리한 탄소나노튜브의 물리화학적 특성은 X-ray photoelectron spectroscopy (XPS), $N_2$ adsorption isotherm, thermogravimetric analysis (TGA), 그리고 temperature programmed desorption (TPD)을 이용하여 분석하였다. 실험 결과, 활성화된 탄소나노튜브 표면의 아미노 관능기는 산성가스인 이산화탄소를 선택적으로 흡착하기 위한 염기성 자리로서 작용하였다. 상온에서의 이산화탄소 흡착량은 미처리된 탄소나노튜브가 가장 크게 나타났으나 온도가 증가할수록 급격한 감소를 나타내었으며 PEHA 처리한 경우 완만한 흡착거동을 보였다. 이는 탄소표면의 아미노 관능기와 이산화탄소 사이의 상호작용 때문이라 판단된다.

• 대한화학회지
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• 제6권2호
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• pp.148-154
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• 1962

The reactions between organic halides$(CCl_4,\;C_6H_5Br,\;C_6H_5Cl,\;C_6H_5I)$ and amines $(C_6H_5NH_2,\;R_2NH,\;R_3N,\;(CH_2)_5NH,\;pyridine)$ were studied under mixed u.v. irradiation. The modes of reactions were examined by means of gas chromatography and product-reactant ratio determination. The reaction of $CCl_4$ with amines give chloroform and hexachloroethanes, and the reaction of aromatic halides with amines gave biphenyl and benzene. In each series of reaction there obtained mainly corresponding amine hydrohalides, but no amination products. The reactivity was in the order of the basicity of amines and of the reactivity of organic hahides, except in the case of cyclic tertiary amine. The result was interpreted as a non-chain photodecomposition process. A competitive proton abstraction reaction path via the formation of a change transfer complex was proposed as the reaction mechanism.