• Journal of the Korean Applied Science and Technology
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• v.7 no.1
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• pp.13-24
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• 1990

2-N,N,N-trimethyl ammonia decanoate, 2-N,N,N-trimethyl ammonio dodecanoate, 2-N,N,N-trimethyl ammonia tetradecanoate and 2-N,N,N-hexadecanoate with in straight long chain alkyl carboxybetaines, and N-decyl N,N-dimethyl ammonio ethanoate, N-dodecyl N,N-dimethyl ammonia ethanoate, N-tetradecyl N,N-dimethyl ammonia ethanoate and N-hexadecyl N,N-dimethyl ammonia ethanoate with in nitrogen-straight long chain alkyl carboxy betaines measured respectively surface tensions by the stalagmometer method at various temperature, also their critical micelle concentration were evaluated. In micellization, the contribution of standard free energy change(${\Delta}G^{\circ}m$), standard enthalpy change(${\Delta}H^{\circ}m$) and standard entropy change (${\Delta}S^{\circ}m$), have been calculated, with increasing temperature. ${\Delta}H^{\circ}m$ changes from negative, and a similar change in the sign of ${\Delta}H^{\circ}m$ is observed with increasing chain length at $25^{\circ}C$, while the entropy of micellization, ${\Delta}S^{\circ}m$ is positive over the temperature range studied, it becomes less so at higher temperatures. Estimates of the enthalpy and entropy contribution attributable to the ion head group and alkyl chain have been made. The enthalpy and entropy change, per methylene group increase respectively with increasing chain length the result are discussed in terms of current theories of micellization.

• KSBB Journal
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• v.17 no.6
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• pp.543-548
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• 2002

The enantioselective esterification of racemic ibuprofen catalyzed by a Candida rugosa lipase was studied according to reaction conditions such as a lipase concentration, reaction temperature, alcohol chain length and alcohol concentration. The S-(+)-ibuprofen alkyl esters prepared were converted to S-(+)-ibuprofen by hydrolysis with sulfuric acid as a catalyst. High conversions in the esterifications were obtained at 60$^{\circ}C$ and an equimolar ratio of octanol to ibuprofen. The initial reaction rate of the esterification decreased with increasing octanol concentration. Conversion and initial reaction rate increased with increasing alcohol chain length. Values of enantiomeric excess(ee) according to esterification reaction conditions did not change below 60$^{\circ}C$. On the other hand, values of conversion and ee for the chemical hydrolysis of S-(+)-ibuprofen alkyl esters were independent of alcohol alkyl chain length. Optical resolution of racemic ibuprofen was achieved by lipase catalyzed esterification and chemical hydrolysis. The separation method provided a high yield and enantioselectivity for the production of S-(+)-ibuprofen from racemic ibuprofen.

• Bulletin of the Korean Chemical Society
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• v.24 no.3
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• pp.377-383
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• 2003

Physicochemical properties of a series of PC monolayers with different alkyl chains (C24, C20, C16, and C8), at the air/water interface were investigated. The surface pressure is influenced mainly by the hydrophobicity of the PCs, which is confirmed by the curve shape and the on-set value of π-A isotherms at the air/water interface by increasing the number of alkyl chain. The on-set values of surface pressure were 125 Ų/molecule for DOPC(C8), 87 Ų/molecule for DPPC(C16), 75 Ų/molecule for DAPC(C20), and 55 Ų/molecule for DLPC(C24), respectively. The orientations of alkyl chains at the air/water interface are closely connected with the rigidity of the monolayers, and it was confirmed by the tendency of monolayer thickness in ellipsometry data. The temperature dependence of a series of PCs shows that the surface pressure decreases by increasing temperature, because the longer the alkyl chain length, the larger the hydrophobic interaction in surface pressure. The temperature effects and the conformational changes of unsaturated and saturated PCs were confirmed by the computer simulation study of the cis-trans transition with POPC and DPPC(C16). The cistrans conformational energy difference of POPC is 62.06 kcal/mol and that of DPPC(C16) is 6.75 kcal/mol. Due to the high conformational energy barrier of POPC, phase transition of POPC is limited in comparison with DPPC(C16).

• Journal of the Society of Cosmetic Scientists of Korea
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• v.22 no.1
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• pp.70-83
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• 1996

자외선 차단제는 화장품 원료 중 주요 자극원의 하나이다. 그러나 자오선 차단제를 고분자로 만들 경우 피부에 도포 되었을 때 경피흡수가 불가능 하여 피부 자극 문제를 해결할 수 있다. 이에 본 연구에서는 PVBC와 alkylhydroxycinnamate를 반응시켜 고분자 자외선 차단제를 합성하였다, PVBC는 benzylic chloride를 가지고 있는 고분자로서 이 작용기는 친핵성 치환반응이 용이하므로 side chain modification이 가능하다. PVBC와 alkyl hydroxycinnamate의 반응에서 반응성은 alkyl hydroxycinnamate의 크기와 반응에 첨가된 촉매의 종류에 영향을 받는다. 효율이 낮은 촉매를 사용할 경우에는 alkyl hydroxycinnamate의 크기가 작을수록 반응수율이 높았으며, 높은 효율을 갖는 촉매를 사용할 경우에는 alkyl hydroxycinnamate의 종류에 관계없이 반응수율은 100%였다. 실험에 사용한 PVBC는 평균 분자량이 55,000이었으며, 고분자의 구조와 분자량은 NMR과 GPC로 확인하였다. 고분자 자외선 차단제의 자외선 흡수 능력은 OMC에 비해 65 - 94% 였으며, caprylic/capric triglyceride에 좋은 용해도를 보여주었다.

• Journal of the Korean Applied Science and Technology
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• v.7 no.2
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• pp.11-18
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• 1990

N-alkyl carboxy pyridinium chlorides such as N-lauryl carboxy-pyridinium chloride, N-myristyl carboxy pyridinium chloride, N-cetyl carboxy pyridinium chloride and N-stearyl carboxy pyridinium chloride were synthesized by the reaction of nicotinic acid and isonicotinic acid with long chain alkyl chlorides, and N-alkyl pyrinium carboxylates such as N-lauryl pyridinium carboxylate, N-myristyl pyridinium carboxylate. N-cetyl pyridinium carboxylate and N-stearyl pyridinium carboxylate were prepared from N-alkyl carboxy pyridinium chlorides. These reaction products could be separated by both column chromatogrphy, and paper chromatography, and there dissociation constants of N-alkyl pyridinium carboxylates were found to pKa $1.0{\times}10^{13}{\sim}6,31{\times}10^{14}$.

• Journal of the Korean Chemical Society
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• v.27 no.6
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• pp.457-463
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• 1983

-Alkyl-2-hydroxyphenazine-5,10-dioxides were synthesized from hydroquinone, and alkyl benzofuroxanes which were previously obtained through five reaction steps starting from aniline. Infrared, nuclear mangnetic resonance spectrometry and elemental analysis were employed to identify the products concerned in the synthetic processes. It was observed that these alkylated phenazine oxides lowered the surface tension of water substantially. These derivatives showed stronger antimicrobial activity against both gram positive and negative microbes than 1-carboxyphenazine which had no alkyl side chain. It was also found that the antimicrobial activity of the phenazine compound increased when the nitrogen of the ring was bound to the oxygen atom.

• Polymer(Korea)
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• v.36 no.3
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• pp.262-267
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• 2012

2-(1,3,3-Trimethyl-6-azabicyclo [3,2,1]-oct-6-yl)-4,5-dihydro-1,3-oxazoline (TAO) was polymerized at several conditions to clarify the influence of initiators, alkyl halide ($PhCH_2Br$, $PhCH_2Cl$, MeI) and sulfonate (MeOTf). The reactions were conducted at $100^{\circ}C$ for 24 h. The resultant polymer forms several kinds of structures with different combination of initiators. The sole MeOTf initiator caused chain transfer reaction to form the one-order structure for which the resultant polymer exclusively formed pendant structure, while alkyl halide and MeOTf formed two kinds of structures, pendant and main chain, which is caused by partly-proceeded double isomerization polymerization by highly reactive nucleophilic counter anion of halogen. Merrifield polymer was also utilized as an intiator and copolymerized with TAO, which produced a graft structure.

• Applied Chemistry for Engineering
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• v.22 no.4
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• pp.367-375
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• 2011

Succinic acid ester derivatives have been used as additives for the base oil of metal working fluids and pressure working oils. In this paper, a series of succinic acid alkyl half-esters were synthesized with over 97% yields by ring-opening reaction of succinic anhydride and fatty alcohol and were soluble in 100 N base oil within 1 wt% concentration. The structures and purities of ester derivatives were confirmed by $^1H-NMR$ and FT-IR spectrum and GC analysis. Anti-corrosion properties of the esters in sea water were evaluated through ASTM D665 method and weight loss method and compared to that of succinic alkyl esters without carboxylic acid group in the molecule. As the results, anti-corrosion properties of succinic acid alkyl half-esters with carboxylic acid group were better than those of succinic acid alkyl esters without carboxylic acid group. And, Anti-corrosion properties of the esters with a shorter alkyl chain of high concentration showed better performance than those with longer alkyl chain of low concentration. Inhibition efficiency % (IE%) of the esters was over 95% in the concentration of 80 ppm and corrosion rate (CR) was below 0.3 mm/year at the same concentration. Thus, the corrosion properties of succinic acid alkyl half-esters result from the carboxylic acid groups in molecules.

• Bulletin of the Korean Chemical Society
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• v.17 no.8
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• pp.700-706
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• 1996

We present the results of molecular dynamics simulations of monolayers of long-chain alkyl thiol [S(CH2)15CH3] molecules on an air-solid interface using the extended collapsed atom model for the chain-molecule and a gold surface for the solid surface. Several molecular dynamics simulations have been performed on monolayers with areas per molecule ranging from 18.30 to 32.10 Å2/molecule. It is found that there exist three possible transitions: a continuous transition characterized by a change in molecular configuration without change in lattice structure, a sudden transition characterized by the distinct lattice defects and perfect islands, and a third transition characterized by the appearance of a random, liquid-like state. The analysis of probability distributions of the segments shows that the structure of the chain-molecules at the air-solid interface is completely different from that at the air-water interface in the view of the degree of overlap of the probability distributions of the neighbor segments. The calculated diffusion coefficients of the chain-molecules on the monolayers seem to be not directly related to any one of the three transitions. However, the large diffusion of the molecules enhanced by the increment of the area per molecule may induce the second transition.

• Journal of the Korean Vacuum Society
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• v.15 no.2
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• pp.145-151
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• 2006

The molecular assembly of p-iodo-phenyl octadecyl ether (I-POE), p-iodo-phenyl docosyl ether (I-PDE) and a binary mixture of these two molecules on graphite has been studied using a scanning tunneling microscope. Each molecular system self-assembles on the graphite surface to form a stable monolayer with a head-to-tail configuration. For the binary system, the I-POE and I-PDE molecules do not mix on the surface, preferring instead to form isolated monolayer domains. Here, the I-POE molecules are preferentially adsorbed on the graphite surface, due to the effects of alkyl chain length and the functional group on the monolayer structure.