동위원소를 이용한 충비 요소방응탑의 혼합특성에 관한 연구

이익춘,강웅기 한국화학공학회 1964 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.2 No.2

The mixing characteristics of the urea reactor of Chungju Fertilizer Plant was studied by the instant injection of C^(14)O₂ radioactive tracer at the feed and analyzing the radioactivity at the outlet. The experimental results were compared with that of theoretical models and the results were agreed well with the model of 90% complete mixing succeeded by 10% plug flow with diffusion and 30% recirculation. The average residence time obtained is 33.0 minutes. The rates of reactions, NH₃+CO₂ to carbamate and carbamate to urea, were compared by analyzing the radioactivities of carbamate and urea, separately. The reaction time obtained by this methed agrees well with the previous study.

파라-치환 브롬화 벤질의 가용매 분해반응 메카니즘

이익춘,엄태섭,성대동,이종팔,박현석,Lee, Ik Chun,Eom, Tae Seop,Sung, Dae Dong,Lee, Jong Pal,Park, Hyeon Seok 대한화학회 1990 대한화학회지 Vol.34 No.1

파라-치환 브롬화 벤질의 가용매 분해반응을 DMSO-<TE>$H_2O$과 DMF-<TE>$H_2O$ 혼합용매계에서 속도론적으로 연구 하였다. 이 두 혼합용매계의 이온화력(Y)와 친핵도($N_{BS}$)를 결정하기 위하여 같은 혼합용매속에서 1-adamantyl halides, t-butyl halides 그리고 methyl tosylate를 가용매 분해반응시켰다. 각 DMSO-<TE>$H_2O$ 혼합용매에 대한 분광용매화 파라미터는 측정된 νmax를 Taft의 관계식에 대입시켜 결정하였다. 파라-치환 브롬화 벤질의 가용매 분해반응은 m, l값과 ${\beta},{\rho}_s$값으로 보아 전이상태에서 결합형성이 약간 우세한 경계반응 메카니즘으로 진행함을 알았다. Solvolyses of p-substituted benzyl bromides have been studied in dimethylsulfoxide-water and N,N-dimethylformamide-water mixtures by kinetic method. To determine the ionizing power, Y and the nucleophilicity, $N_{BS}$, the solvolyses of 1-adamantyl halides, t-butyl halides, and methyl tosylate in the same solvent mixtures have been investigated. The solvatochromic parameters for each dimethylsulfoxide-water mixtures have been determined by substituting into the Taft's linear solvatochromic energy relationships with measured $ν_{max}$. The solvolyses of p-substituted benzyl bromides have been found to proceed by borderline mechanism in which bond formation is more advanced than bond cleavage in the transition state based on the m, l values and ${\beta},{\rho}_s$, values.

Linear Relationships between Thermodynamic Parameters (Part III) Application to Solvolysis Reaction

이익춘,Ikchoon Lee Korean Chemical Society 1963 대한화학회지 Vol.7 No.4

前報에서 誘導한 置換基效果 一般關係式은 溶媒組成에 따르는 常數, Y를 potential energy 項에 代置함으로서 solvolysis 反應에 適用할 수가 있다. 新方程式, $\Delta{\Delta}H^\neq=a'Y+b\Delta{\Delta}S^\neq$, 의 適用性은 文獻에 報告된 35個反應에 對한 直線關係를 調査해 봄으로서 檢討하였다. 結果로 平均 相關係數 0.977을 얻었고, 따라서 이 方程式이 solvolysis反應에 一般的으로 適用됨을 밝혔고, 또 Grunwald-Winstein의 式이 지니는 몇몇 難點을 解決할 수가 있음을 알 수 있었다. enthalypy-entopy 直線效果는 外部 enthalpy와 外部 entropy에 限한 것이며, 嚴格히 말해서 外部 enthalpy entropy 直線效果임을 强調하였다. The general equation for the substituent effect test, which was derived in the previous paper, has been extended to correlate thermodynamic parameters of solvolysis reaction by modifying the potential energy term to represent the effect of changes in solvent composition. The linear fits of the new equation, $\Delta{\Delta}H^\neq=a'Y+b\Delta{\Delta}S^\neq$, were tested with 35 examples from literature and average correlation coefficient of 0.977 was obtained. Examination of results showed that the equation is generally applicable to solvolysis reaction and helps elucidate some the difficulties experienced with the Grunwald-Winsteln equation. It has been stressed that the linear enthalpy-entropy effect exists only between the external enthalpy and entropy of activation, and therefore strictly it is the linear external enthalpy-entropy effect.

Liquid Scintillation Counting 에서의 Dimethylaniline 에 依한 消光機構

이익춘,Lee, Ik-Choon 대한화학회 1964 대한화학회지 Vol.8 No.2

Quenching constants, q, determined for N,N-dimethylanilines by liquid scintillation counting indicate that the quenching involves an energy transfer process to these compounds causing strong n-${\pi}$ interaction within the quencher molecule, which is then followed by an non-radiative degradation of the excitation energy to ground state.

Linear Relationships between Thermodynamic Parameters (Part V) Critical Evaluation and Mechanistic Significances of the Relationship

이익춘,Lee, Ik-Choon Korean Chemical Society 1965 대한화학회지 Vol.9 No.1

Justifications for the use of ${\sigma}$ and Y as independent potential energy variables in the general equation have been reviewed and some mechanistic significances of the relationship discussed. Analysis of the activation parameters for the solvolysis of benzyl chlorides in ethanol-water mixture showed that there are two distinct series of substrate constants ${\alpha}'$, which can be correlated linearly within a series with the substituent constants ${\sigma}$ conforming to the generally accepted concept of change in mechanism from $S_N1$ to $S_N2$. 一般式中의 potential energy 變數로서 ${\sigma}$ Y를 使用할 수 있음을 밝혔고 또 關係式의 反應機構上의 意義를 論하였다. Benzyl chlorides의 solvolysis反應 data를 適用함으서 物質常數 ${\alpha}'$는 2個의 뚜렷한 系列을 形成하며 置換基常數 ${\sigma}$와는 各系列마다 別途로 直線關係를 가지며 이로서 $S_N1$으로부터 $S_N2$로의 反應機構의 變化를 알 수가 있었다.

熱力學 函數間의 直線關係 (第1報) 理論

이익춘,Ikchoon Lee 대한화학회 1963 대한화학회지 Vol.7 No.3

Inter-relationship between the Hammett equation and the linear enthalpy-entropy effect has been discussed by deriving a new set of equations; ${\Delta}{\Delata}H^{\neq}=a{\sigma}+b{\Delta}{\Delta}S^{\neq}$ and ${\Delta}{\Delta}F^{\neq}=a{sigma}+(b-T){\Delta}{\Delta}S^{\neq}$ where a = -1.36p. Theoretical analysis show that the Hammett, Leffler and Brown equations are special limited forms of these general equations. A necessary and sufficient test of substituent effect can thus be provided by the plot of $({\Delta}{\Delta}H^{\neq}-a{\sigma)$ versus ${\Delta}{\Delta}S^{\neq}$.

화학반응성의 분자궤도론적 연구 (제5보). 염화알킬의 친핵성치환 반응성에 대한 시그마 분자궤도론적 연구

이익춘,이본수,김광수,Ikchoon Lee,Bon-Su Lee,Kwang-Su Kim 대한화학회 1973 대한화학회지 Vol.17 No.2

Ground electronic structures and SNreactivities of a series of alkylchlorides (methyl,ethyl, iso-propyl, trans n-butyl, sec-butyl, tert-butylchloride) have been studied using approximate $({\sigma}-MO)$ method, such as EHT and CNDO/2. It was found that CNDO/2 gives better results for the systems such as alkylchlorides whose structural differences are not remarkable, in comparison with EHT method. According to CNDO/2 results, calculated dipole moments for alkylchlorides are slightly higher than observed values, showing the order of primary < secondary < tertiary alkylchlorides. It was also found that highest occupied(HO) MO's are completely or nearly degenerate, and show relatively weak $\pi$-antibonding nature between$\alpha$-carbon and Cl atoms. Furthermore, the electrons in this MO are largely confined to Cl atom, and hence these behaves as likely as p-lone pair electrons of Cl atom. On the contrary, lowest unoccupied (LU) MO's show strong $\sigma$-antibonding nature between $\alpha$-carbon and Cl atoms whose electron clouds are directed along the C-Cl axis. It has been discussed that the$S_N2$ reactivities of alkylchlorides may largely be controlled by ${\sigma}^{\ast}$ LUMO, and the antibonding strength between $\alpha$-carbon and Cl atoms in this MO may become the measure of $S_N2$reactivity. The relationship between $S_N2$reactivity and C-Cl bond polarizability has also been discussed. It has been suggested that the unique structure factors determining $S_N1$reactivities may be $\pi$-antibonding strength between $\alpha$-carbon and Cl atoms in HOMO and C-Cl bond strength in ground state. 일련의 염화알킬(염화메틸, 에틸, 이소-프로필, 트란스 n-부틸, sec-부틸, tert-부틸)의 바닥 상태 전자구조와 친핵성 치환반응성을 근사적 시그마 분자궤도법$(\sigma-MO)$인 EHT 와 CNDO/2 법을 이용하여 비교 검토하였다. 염화알킬처럼 상호 구조적 차이가 현저하지 못한 경우에 있어서는 EHT법이 CNDO/2 법에 비하여 비교적 부정확함을 알았다. CNDO/2 계산에 의하면, 쌍극자모멘트의 계산치가 실험치 보다 약간 크게 주어지며 대체로 primary<secondary<tertiary염화알킬의 순서임을 보여주었다. 염화알킬의 최고 점유궤도함수(HOMO)는 완전히 또는 거의 가깝게 중첩되어 있으며 $\alpha$탄소와 Cl사이에 비교적 약한 $\pi$-반결합 $({\pi}^{\ast})$성을 가지고 있으며, 전자밀도가 거의 염소원자에 집중되어 있어 염소의 p-고립상 전자와 같은 특성을 가지고 있음을 알았다. 그 반면 최저 비점유 궤도함수(LUMO)는$\alpha$탄소와 염소 사이에 강한 시그마-반결합$({\alpha}^{\ast})$성을 가짐을 알았다. 염화알킬의 $S_N2$반응성은 주로 $\alpha$인 LUMO에의하여 좌우되며, 특히 이 MO에서 $\alpha$탄소와 염소간의 반결합 세기가 $S_N2$반응성의 척도가 될 것으로 예측되며, 결합-polorizability와의 관련성도 논의하였다. 염화알킬의 $S_N2$반응성은 주로 ${\pi}^{\ast}$인 HOMO에서 $\alpha$탄소와 염소간의 반결합 세기가 큰 역할을 하며 바닥상태의 C-Cl결합세기도 상당한 역할을 할 것으로 기대된다.

열역학함수간의 직선관계 (제6보) 염화벤질의 염소교환에 미치는 용매효과

이익춘,박용자,Lee, Ik-Choon,Park, Yong-Ja 대한화학회 1968 대한화학회지 Vol.12 No.4

Rate constants and activation parameters have been petermined for the chloride exchanges of benzyl chloride in 60, 70, 80 and 90 vol.% ethanol-water solutions. Results showed a good linearity when appiled to our general equation. The significance of this linear fit has been discussed in conjunction with the Dewar's relation which was derived from the PMO method.

MO Studies of Configuration and Conformation (Ⅳ). Conformations of N-Acetyl Pyrrolidone and Its Protonated Form

이익춘,이석기,김시준,전용구,Ikchoon Lee,Suk Kee Lee,Shi Choon Kim,Young Gu Jeon Korean Chemical Society 1978 대한화학회지 Vol.22 No.2

N-아세틸피롤리돈과그 양성자 형태에 대하여 EHT 및 CNDO/2 분자궤도함수법으로 연구하였다. 계산결과는 분자내의 무거운 원자들의 골격이 평면구조인 경우가 가장 안전하며, 평면형태에서는 트란스-트란스형이 시스-트란스형보다 더 안정함을 나타내고, 양성자화는 고리에 붙어있는 카르보닐 산소에서 더 용이하게 일어남을 나타내고 있다. 이 결과를 콘주게이션, 정전기적 및 입체효과로서 설명하였다. MO theoretical studies on the conformations of N-acetylpyrrolidone and its protonated form were carried out by the EHT and CNDO/2 methods. According to our calculated results, the heavy atom skeleton of this molecule is planar, and the trans-trans planar conformation is more stable than cis-trans. The protonation occurs most readily on the ring carbonyl oxygen. These results were interpreted in terms of conjugative, electrostatic and steric effect.

Linear Relationships between Thermodynamic Parameters (Part II) Applicabiliy of New Equations

이익춘,박용자,Ikchoon Lee,Yong Ja Park Korean Chemical Society 1963 대한화학회지 Vol.7 No.4

前報에서 誘導한 새로운 直線關係式,${\Delta}{\Delta}H^{\neq}=a{\sigma}+b{\Delta}{\Delta}S^\neq$ 및 ${\Delta}{\Delta}F^{\neq}=a{\sigma]+(b-T){\Delta}{\Delta}S^{\neq}$, 의 適用性을 57個反應으로 檢討하였다. 57個反應에 대한 ${\Delta}{\Delta}H^{\neq}-a{\sigma}$, 對 ${\Delta}{\Delta}S^{\neq}$의 直線關係 相關係數의 平均은 0.983이었고 直線으로부터의 標準備差의 平均値는 0.11이었다. 57個反應中 15個反應에 對해서는 Hammett方程式이 成立되지 않었고, 또 大部分의 反應에 對해서 Leffier의 式이 成立하지 않었다. 이와같이 從來의 關係式 이 成立하지 않는 反應도 새로운 關係式으로 設明되며, 그 理由를 檢討해 봄으로써 上記 2式이 더 一般的으로 適用되는 關係式임을 確認하였다. Linear relationships between thermodynamic parameters, ,${\Delta}{\Delta}H^{\neq}=a{\sigma}+b{\Delta}{\Delta}S^{\neq}$, and $\Delta{\Delta}F^\neq=a\sigma+(b-T)\Delta{\Delta}S^\neq$, which were derived in the previous report have been tested with 57 reactions from literature. Linearities of plots $\Delta{\Delta}H^\neq-a\sigma$ vs. $\Delta{\Delta}S^\neq$ were generally good and the average correlation coefficient was 0.983 and the average of standard deviations from regression lines was 0.11. For 15 out of 57 reactions, Hammett plots were unsatisfactory and most of the reaction did not satisfy the Leffler equation. The general applicability of the new equations has been confirmed by the analysis of each reaction for which existing equations failed to correlate.