• Bulletin of the Korean Chemical Society
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• 제22권12호
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• pp.1316-1322
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• 2001

Transition metal complexes of novel mono- and di-ferrocene-substituted porphyrins have been synthesized and characterized by structural and electrochemical methods. The X-ray structures of Mn(FPTTP)Cl and Mn(DFTTP)Cl showed the distorted square pyramidal coordination geometry with syn configuration of chloride and ferrocenyl substituents. The electrochemistry of ferrocene-substituted porphyrins and their metal complexes has been determined to elucidate the ${\pi}-conjugation$ effect of the porphyrin ring. The ferrocenyl group of H2FPTTP underwent a reversible one-electron transfer process at 0.30 V, indicating the good electron donating effect of the phorphyrin ring to the ferrocene substituent. The redox potential of the ferrocenyl subunit and porphyrin ring was affected by the central metal ions of the metalloporphyrins, that is, Zn(II) and Ni(II) made the oxidation of ferrocene much easier and Mn(III) made it harder. The ferrocene subunits of H2DFTTP interacted electrochemically with each other with peak splitting of 0.21 V. The strength of the electrochemical interactions between the two ferrocenyl substituents can be controlled by central metal ions of metalloporphyrins.

• Bulletin of the Korean Chemical Society
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• 제23권4호
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• pp.549-554
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• 2002

Thermosensitive poly(organophosphazenes) bearing methoxy-poly(ethylene glycol) (MPEG) and alkylamines as substituents have been synthesized and characterized by elemental analysis, NMR spectroscopy, GPC, and DSC. All the polymers exhibited crystallinity, which was probably induced by the MPEG side chain of the polymers. All the polymers exhibited the lower critical solution temperature (LCSTs) in the range of 28 to $94^{\circ}C$ depending on several factors such as mole ratio of the substituents, kinds of PEG and alkylamines. The higher content of MPEG and shorter chain length of alkylamines of the polymers afforded the higher LCST. The LCSTs of the polymers exhibited almost concentration-independent behavior in the range of 3-30 wt % of the polymers in aqueous solutions. The polymers showed the higher LCSTs in the acidic solutions than in the neutral and basic solutions. The ionic strength of the polymer solution affected the LCST, which decreased with increased NaCl concentration. The polymer bearing almost equimolar substitutuents with the -N-P-N- unit has shown the LCST more sensitive to NaCl and pH than that with the -N-P-O- unit. The polymers were found to degrade in acidic solution but be very stable in alkali solution as well as in the buffer solution of pH 7.4.

• Journal of Dairy Science and Biotechnology
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• 제33권1호
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• pp.47-57
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• 2015

세계보건기구(World Health Organization)는 식료품에 함유된 NaCl을 낮출 것을 권하고 있으며, 식품 내 NaCl 수치 감소시키는 것은 중요한 연구분야가 되었다. 염화나트륨(sodium chloride, NaCl)의 과다 섭취는 고혈압, 골다공증, 뇌졸증, 신장결석, 심혈관계 질환 등의 다양한 질병과 직접 또는 간접적으로 많은 연관되어 있다. 산업국가에서는 치즈등의 가공식품을 통해 많은 양의 소금을 섭취하고 있기 때문에, 치즈 내 NaCl의 함유량 감소에 대한 연구가 진행 중에 있다. 따라서 최근에 치즈 내 NaCl의 함유량을 감축하기 위한 많은 방법들이 이용되고 있다. NaCl은 치즈 내에서 방부제 역할을 하며, 식품의 풍미를 높이고, 치즈의 주요 기능적 특성을 담당하기 때문에, 치즈의 품질에 영향을 주지 않으면서 치즈에 함유된 NaCl을 감소하는 것은 쉽지 않다. 대체방법을 사용하지 않고, 치즈에 함유된 NaCl을 감축시키는 연구가 진행되어 왔지만, NaCl 감소 시에 발생하는 식품의 관능적 특성, 유동학 및 안정성 문제들이 보고되고 있다. 지금까지의 연구 결과에 의하면 식품 내 NaCl을 감소시키는 방법으로는 NaCl 대체(NaCl substitution)라고 불리는 방법이 있으며, 이 방법은 NaCl을 부분적으로 다른 염분(염화칼륨, 염화마그네슘, 염화칼슘)으로 대체함으로써 식품에 함유된 NaCl 수치를 감소시킨다. 실례로 자연치즈에 함유된 NaCl을 KCl로 대체하였을 때 치즈의 특성, 특히 맛에 변화와 안정선에 문제가 야기되었다. 반면, 가공치즈에 함유된 NaCl을 KCl로 대체하였을 때, 치즈의 특성이 큰 영향을 받지 않았기 때문에, 이 방법을 사용하여 치즈에 함유된 NaCl의 수치를 감소시킬 수 있는 가능성이 높다는 것을 나타냈다. 이와 같은 결과는 자연치즈 내의 NaCl 함량을 감축하기 위해서는 치즈에 함유된 NaCl의 역할, NaCl과 건강문제, NaCl 감소 방법, 다른 염분(특히 염화칼륨으로 NaCl 대체하는 방법)을 사용하는 방법 등에 관한 더 많은 향후 연구가 많이 필요하며, 적극적으로 진행되어야 할 것이다.

• 대한화학회지
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• 제50권1호
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• pp.46-52
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• 2006

착물을 촉매제로 하여 용매인 CH2Cl2와 산화제 NaClO를 사용하여 올레핀 산화반응의 메카니즘 연구를 하였다. 이들 반응에서 포르피린의 치환기는 TPP(5,10,15,20-Tetraphenylporphyrin)와 (p-X)TPP(X=CH3O, CH3, F, Cl)를, 올레핀은 styrene과 (p-X)styrene (X=CH3O, CH3, Cl, Br)을 사용하였다. 일반 효소반응에서 잘 알려진 Michaelis-Menten식에 따라 Km과 Vmax 값을 구하였다. Michaelis-Menten 식의 속도 파라미터를 포르피린 치환기에 따라 측정하고, 이들 파라미터와 치환기상수 간의 상관성을 조사함으로써 올레핀 산화반응의 중간체 M-oxo-olefin의 형성 과정과 분해 과정이 촉매활성이나 속도 결정 단계의 변화에 미치는 영향을 분석 하고자 하였다.

• Bulletin of the Korean Chemical Society
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• 제18권4호
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• pp.402-405
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• 1997

Olefinic and cyclopropyl group substituted arenes (C6H5Y) react with [Cp*Ir(CH3COCH3)3]A2 (A=ClO4-, OTf-) to give η6-arene complexes, [Cp*Ir(η6-C6H5Y)]2+ (1a: Y=-CH=CH2 (a),-CH=CHCH3 (b),-C(CH3)=CH2 (c),-CH-CH2-CH2 (d)). Complex 1b-1d are readily converted into η3-allyl complexes, [Cp*(CH3CN)Ir(η3-CH(C6H5)CHCH2)]+ (2a) and [Cp*(CH3CN)Ir(η3-CH2(C6H5)CH2)]+ (2b), in the presence of Na2CO3 in CH3CN. The η6-styrene complex, 1a reacts with NaBH4 to give η5-cyclohexadienyl complex, [Cp*Ir(η5-C6H6-CH=CH2)]+ (3), while with H2 it gives η6-ethylbenzene complex [Cp*Ir(η6-C6H5CH2CH3)]2+ (4). Complex 1a and 1c react with HCl to give [Cp*Ir(η6-C6H5CH2CH2Cl)]2+ (5a) and [Cp*Ir(η6-C6H5CH(CH3)CH2Cl]2+ (5b), respectively.

• 공업화학
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• 제25권1호
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• pp.20-26
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• 2014

양이온성 계면활성제인 tetradecyltrimethylammonium bromide (TTAB) 수용액에서 p-할로겐화 페놀유도체들의 가용화현상을 UV/Vis 분광광도법을 이용하여 연구하였다. 가용화현상에 미치는 치환기, 첨가제 및 온도의 효과를 조사하였다. 모든 페놀유도체의 가용화에 대한 ${\Delta}G^o$와 ${\Delta}H^o$ 값은 측정범위 내에서 모두 음의 값을 나타내었으며, ${\Delta}S^o$ 값은 모두 양의 값을 나타내었다. 특히 이들 열역학 함수값들은 할로겐 치환기의 크기, 전기음성도 및 소수성에 크게 영향을 받았다. n-부탄올 첨가제는 모든 페놀유도체의 가용화를 감소시켰으며, NaCl 첨가제는 오히려 가용화를 촉진시켰다. 이런 결과들로부터 페놀유도체들은 치환기의 성질에 따라 미셀 내에서 가용화되는 위치가 서로 다름을 알 수 있었다.

• Journal of Microbiology and Biotechnology
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• 제12권2호
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• pp.209-216
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• 2002

Bacillus sp. A56 was studied, because of its high flocculating activity. The flocculating substance produced by this strain was purified by ethanol precipitation, cetylpyridinium chloride (CPC) precipitation, and gel permeation chromatography (GPC). The FT-IR spectrum of the purified bioflocculant, designated as BF-56, showed typical characteristics of polysaccharides. The non-sugar substituents, and sugar components of BF-56 containing glucose, fucose, glucuronic acid, and galactose in an approximate molar ratio of 2.76:1.10:1:0.12, suggested that it was a novel bioflocculant with an estimated molecular mass of over $7{\times}10^3$ kDa. Rheological analysis of BF-56 revealed that it was a pseudoplastic that had higher apparent viscosity rate at dilute concentrations than those of zooglan. The solution of bioflocculant BF-56 exhibited non-Newtonian characteristics and it was compatible to high concentrations of salts such as KCl, NaCl, $CaCl_2,\;or\;FeCl_3.$ The present results suggested strong possibility of bioflocculant BF-56 to be fully applicable to industries such as wastewater treatment.

• Bulletin of the Korean Chemical Society
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• 제27권12호
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• pp.2023-2027
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• 2006

Dibenzyl sulfide was oxidized at the a-carbon to yield benzaldehyde in the presence of $Pd(NO_3)_2$. Oxygen itself could not oxidize the sulfide directly, instead the nitrato ligand of the palladium complex transferred oxygen to dibenzyl sulfide to form benzaldehyde. The X-ray crystal structure of the intermediate complex, cis-[$Pd(NO_3)_2${$S(CH_2C_6H_5)_2$}$_2$], revealed that the nitrato ligand was unidentate. Para-substituted dibenzyl sulfides I, $(YC_6H_4CH_2)_2S $wherein Y = $OCH_3$, $CH_3$, Cl, CN, or $NO_2$, were synthesized and reacted with palladium nitrate, and those with electron-donating substituents (Y = $OCH_3$ and $CH_3$) were good substrates for the oxidation reaction with palladium nitrate. Thus, the reaction mechanism of the oxygen transfer was proposed to include nucleophilic benzylic carbon.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.535-538
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• 1999

Five coordinated water-soluble iridium(l) complex, IrH(CO)(TPPTS)3 (1) (TPPTS = P(m-C6H4SO3Na)3-xH2O) has been prepared from the reaction of IrCl3·3H2O with TPPTS and HCHO in H2O/EtOH solution. Complex 1 catalyzes the hydration of nitrites (RC ≡ N, R = CH3, CICH2, CH3(CH2)4, Ph) in aqueous solution to give the corresponding amides (RCONH2) at 100℃. The hydration of unsaturated nitrites (R'C ≡ N, R'=CH3CH=CH, CH3OCH=CH, trans-PhCH=CH, CH2=C(CH3)) takes place regioselectively on-C ≡ N group to give unsaturated amides (R'CONH2) leaving the olefinic group intact. The yields of the amides seem to be depending on the electrophilicity of the carbon of nitrile: The more the electron withdrawing ability of the substituents on nitrites, the more amides are obtained. The hydration of dinitriles (NC-R-CN, R=(CH2)4, (CH2)6) with complex 1 initially gives mono-hydration products (NC-R-CONH2) which are slowly hydrated further to give dihydration products (H2NCO-R-CONH2). The hydration of 1,4-dicyanobutane has been found to be somewhat faster than that of 1,6-dicyanohexane.