• Bulletin of the Korean Chemical Society
• /
• 제8권5호
• /
• pp.408-414
• /
• 1987

The rate of bromine-exchange reaction between antimony tribromide and ${\alpha}-phenyl-n-butyl$ bromide in nitrobenzene has been determined, using antimony tribromide labelled with Br-82. The results indicate that the exchange reaction follows the first-order kinetics with respect to the organic bromide, and either the second- or first-order kinetics with respect to antimony tribromide depending on its concentration. The third-order rate constant obtained was 7.50 ${\times}10^{-2}l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. Similar study on the bromine-exchange reaction between antimony tribromide and ${\alpha}$-phenyl-i-butyl bromide has also been carried out. The results of the study show the same kinetic orders as the ones observed with $\alpha$-phenyl-n-butyl bromide. The third-order rate constant observed was 2.40 ${\times} 10^{-2} l^2mol^{-2}s^{-1}$ at 28$^{\circ}$C. The activation energy, the enthalpy of activation and the entropy of activation for the two exchange reactions mentioned above have been determined. The reaction mechanisms for the exchange reactions are discussed.

• Nuclear Engineering and Technology
• /
• 제22권4호
• /
• pp.410-415
• /
• 1990

MN(Madland-Nix) 모형에 바탕을 둔 핵분열 즉발 중성자 에너지 스펙트럼을 핵분열 유기중성자의 에너지 함수로서 구했다. 이 중성자 스펙트럼을 $^{27}$ Al(n,$\alpha$), $^{32}$S(n,p) 및 $^{115}$ In(n,n') 발단 방사화 검출기의 여기함수에 증율시켜 평균핵반응 단면적을 계산하고 상호간의 비, 즉, 중성자 스펙트럼 지수를 구했다. 그 결과 핵분열 유기중성자의 에너지에 따라 중성자 스펙트럼은 변하며 그에 따라 중성자 스펙트럼 지수도 변함을 보였다. 이것은 곧 중성자 스펙트럼 지수를 실험적으로 결정하므로써 핵분열 즉발 중성자 에너지 스펙트럼을 결정할 수 있음을 의미한다.

• Bulletin of the Korean Chemical Society
• /
• 제15권11호
• /
• pp.985-990
• /
• 1994

Cross-interaction constants, ${\rho}^e_{XY}$, ${\rho}_{YZ}$ and ${\rho}_{XZ}$ are defined using observed rate constant, k_N=(k_1/k_{-1})k_2=Kk_2$, for the stepwise carbonyl addition reactions involving the rate-limiting breakdown of a tetrahedral intermediate $(T^{\pm})$. Abundant experimental evidence in the literature enables us to determine signs for the three constants for such mechanism, ${\rho}^e_{XY}$>0, ${\rho}_{YZ}$<0 and ${\rho}_{XZ}$0. These are in contrast to those for the concerted $S_N2$ mechanism, ${\rho}_{XY}$<0, ${\rho}_{YZ}$>0 and ${\rho}_{XZ}$, and provide useful mechanistic criteria. In the light of these criteria, mechanisms of some nucleophilic reactions of carbonyl compounds are re-examined.

• 한국임상약학회지
• /
• 제21권2호
• /
• pp.138-144
• /
• 2011

In order to minimize such adverse drug reactions, governments and international organs have been on the watch for them. Also in South Korea, a system has been established in order that adverse drug reactions may be reported to Korea Food and Drug Administration(KFDA). This study is to analyze drugs to cause adverse reactions, the adverse reactions and patients concerned on the authority of the data of Korea FDA, which is expected to be the preliminary data on preventable adverse reactions. This study was conducted on the 74,037 cases of adverse drug reactions reported to Korea FDA between January 2007 and June 2010. Fentanyl, iopromide and tramadol caused adverse reactions with high frequencies. Oseltamivir showed a high frequency between 2009 and 2010 due to the influence of the new influenza A. Also, OTC drugs accounted for approximately 5% of the adverse reactions. In 2009, adverse drug reactions remarkably increased (2,106 cases; 10.1%) in infants and children due to the new influenza-A(H1N1). The patients aged between 31 and 64 accounted for approximately 55% during the given period. There was no significant intergender difference. In relation to regions, the adverse reactions most frequently occurred in the gastrointestinal system and the integumentary system for three and half years. In addition to anticancer drugs and immunosuppressive drugs that are known to cause adverse reactions frequently, not a few of OTC drugs and external preparations caused such reactions. In particular, the drugs containing specific ingredients caused adverse reactions more frequently than others from 2007 until the first half of 2010. It is advisable for prescribers to acquaint themselves with such adverse reactions and to prescribe drugs other than them. They also have need to sensibly cope with adverse drug reactions just in case they have no substitute drugs. In addition, patients also need to be trained to understand possible adverse reactions in order that they can sensibly accommodate them or choose healthcare services. The results of this study are expected to be helpful to minimize adverse drug reactions.

• 대한화학회지
• /
• 제43권1호
• /
• pp.85-91
• /
• 1999

Phenyl N,N-diethyl-P-benzylphonamidate 및 그 유도체들의 염기성 가수분해 반응속도 상수를 분광 광도법으로 측정하였다. 속도 상수로부터 열역학적 파라메타(Ea, ${\Delta}H^{\neq}$,${\Delta}S^{\neq}$)를 구하였고, 이탈기의 치환기 효과는 Hammett 식을 이용하여 얻었다. 이들 실험 자료에 의하면 가수분해 반응은 활성화 엔트로피가 양의 값이나 작은 음의 값을 갖고 카르보음이온 생성이 수반되는 해리반응 보다는 이중피라미드 중간체 또는 전이 상태를 경유하는 회합 메카니즘을 강력히 암시하고 있다. 반응속도론적 연구 결과에 의하면 치환 pheny N,N-diethyl-P-benzylphosphonamidates의 가수분해 반응은 회합성 메카니즘으로 진행됨을 알 수 있었다.

• Bulletin of the Korean Chemical Society
• /
• 제10권1호
• /
• pp.80-84
• /
• 1989

Two properties of sodium naphthalenide (2), i.e. a strong base and a good electron donor were utilized for one pot synthesis: 2-alkylthiobenzimidazoles were synthesized in excellent yields from the reactions of benzimidazoline-2-thione (1) with an equimolar amount of alkyl halides in the presence of 2. Continuous addition of a different alkyl halide without the isolation of 2-alkylthiobenzimidazoles afforded 1-alkyl-2-alkylthiobenzimidazoles having different alkyl groups at N and S atoms in excellent yields. Further addition of 2 to 1-alkyl-2-alkylthiobenzimidazoles gave excellent yields of 1-alkylbenzimidazoline-2-thiones. When 2 in THF was added to a suspension of 1-alkyl-2-alkylthiobenzimidazoles in THF, a bond cleavage between N and C of alkyl group as well as S and C of alkyl group occurred. This is in contrast to the observation in which only cleavage between S and C of alkyl group takes place in the homogeneous solution.

• Bulletin of the Korean Chemical Society
• /
• 제30권10호
• /
• pp.2283-2286
• /
• 2009

A convenient route for the preparation of water soluble polythiophenes is described. Reactions involving highly active zinc metal show unique properties, viz. tolerance of the ester group and regioselectivity to the thiophene ring. Poly [3-(ethyl-n-alkanoate)thiophene-2,5-diyl]s, poly [3-(n-carboxyalkyl)thiophene-2,5-diyl]s, and poly [3-(potassium- n-alkanoate)thiophene-2,5-diyl]s were easily prepared by utilizing highly active zinc.

• 대한화학회지
• /
• 제19권4호
• /
• pp.240-245
• /
• 1975

置換 benzyl (X)arensulfornate (Z)와 置換디메틸아닐린(Y)을 아세톤 容媒中에서 Menschatkin型 反應에 對한 벤질核의 置換基 效果를 檢討하였다. Z의 置換基가 電子끄는基에서 주는 基로 變할때 ZY 間에 存在하던 相互作用項이 消失되었다. ZY間의 相互作用項의 유무는 Z의 置換基 變化에 依한 $S_N2{\longrightarrow}S_N1$에의 機構의 變化에 對應된다고 생각된다.

• Bulletin of the Korean Chemical Society
• /
• 제27권3호
• /
• pp.345-354
• /
• 2006

Ionic liquids are alternative reaction media of increasing interest and are regarded as an eco-friendly alternatives, of potential use in place of the volatile organic solvents typically used in current chemical processing methods. They are emerging as the smart and excellent solvents, which are made of positive and negative ions that they are liquids near room temperature. The nucleophilic substitution reaction is one of the important method for inserting functional groups into a carbon skeleton. Many nucleophilic substitution reactions have been found with enhanced reactivity and selectivity in ionic liquid. In this review, some recent interesting results of nucleophilic substitution reactions such as hydroxylations, ether cleavages, carbon-X (X= carbon, oxygen, nitrogen, fluorine) bond forming reactions, and ring opening of epoxides in ionic liquids are discussed.

• 분석과학
• /
• 제8권4호
• /
• pp.815-820
• /
• 1995

Instrumental neutron and gamma activation analysis of coal and combustion products, determination of platinum content in natural samples by radiochemical gamma activation analysis and high-sensitive track method of thorium determination has been studied with the use of the MT-25 microtron.The optimal conditions for complete elemental analysis of coal and combustion products, isolation and determination of platinum and thorium are recommended.