• Tribology and Lubricants
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• 제16권5호
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• pp.332-340
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• 2000

The reduction of sulfur content in the diesel fuel has caused the poor lubricity of diesel fuel in the distributor type injection pumps of diesel engines that use the diesel for lubrication of their moving parts. To investigate the reason for poor lubricity of low sulfur diesel fuels, the wear scar diameters by HFRR (High Frequency Reciprocating Rig) were measured on the diesel fuels from Korean markets and the results were compared with their physical and chemical properties. Also, the lubricity change and the improvement effects on lubricity additives for the ultra low sulfur diesel fuel, were made experimentally, that will be regulated to a maximum of 0.005 wt% from about 2005 were evaluated. As a result, a good correlation was found between the wear scar diameter and the polyaromatic compound which includes heterocyclic compound in the diesel fuel. It was also found that the content of polyaromatic compound including heterocyclic compound was affected by the amount of desulfurization treatment fraction. And the lubricity additives with ester base were more effective than that with acid base on the ultra low sulfur diesel fuel. Therefore, it is suggested that the factors affecting the lubricity stated above should be taken into account to improve the lubricity property of the diesel fuel in the refining process.

• 공업화학
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• 제25권3호
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• pp.330-336
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• 2014

추출-증류-결정의 조합에 의해 모델 콜타르 흡수유 중에 함유된 인돌의 정제를 검토했다. 흡수유는 4종류의 질소고리 화합물(9.2% 퀴놀린, 2.4% 이소퀴놀린, 4.7% 인돌, 2.4% 퀴날딘), 3종류의 2환 방향족 화합물(14.2% 1-메틸나프탈렌, 31.8% 2-메틸나프탈렌, 23.5% 디메틸나프탈렌), 5.5% 비페닐과 3.3% 페닐에테르의 9종류의 화합물로 구성되어 있다. 포름아미드 추출-증류-노말헥산을 사용한 용액 결정화의 조합의 채택에 의해 99.5% 인돌을 회수할 수 있었다. 본 연구를 통해 얻어진 실험적 결과를 이용하여 콜타르 흡수유 중에 함유된 인돌의 회수공정을 검토했다.

• Bulletin of the Korean Chemical Society
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• 제19권1호
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• pp.63-67
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• 1998

The synthesis and characterization of the monomeric group 13 heterocyclic thiosemicarbazone complexes $Me_2M[SC_4H_3CHNNC(S)SCH_3]$ (M=Al (2), Ga (3)) are described. Compounds 2-3 were prepared using $MMe_3$ (M=Al, Ga) in toluene with 2-thiophenecarboxaldehyde-S-methyldithiocarbazat e under anaerobic conditions. These complexes have been characterized by $^1H\;NMR,\; ^{13}C\; NMR$, elemental analyses, and single-crystal X-ray diffraction. 2 crystallizes in the monoclinic space group $P2_1/c$ with unit cell parameters a=10.2930(5) Å, b=18.564 (1) Å, c=7.3812(6) Å, V=1347.9(2) Å3, $D_{calc}=1.342\; gcm^{-3}$ for Z=4, 9281 reflections with $I_o<3{\sigma}\;(I_o),$ R1=0.0500 and wR2=0.0526. 3 crystalizes in the orthorhombic space group $P_{bca}$ with unit cell parameters a=13.340(3) Å, b=19.9070(5) Å, c=11.3690(2) Å, $V=2673.88(9)\;{\AA}^3$, $D_{calc}=1.511\; gcm^{-3}$ for Z=8, 17004 reflections with $I_o>3{\sigma}\;(I_o),$, R1=0.0480 and wR2=0.0524. Compound 3 is a monomeric gallium compound with a weak interaction between the pendant thiophene and the gallium center.

• 대한약침학회지
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• 제24권1호
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• pp.32-40
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• 2021

Objectives: Pathogenic microbes are causal agents for various types of severe and even lethal infectious diseases. Despite of development in medication, bacterial and fungal infections still persist to be a vital problem in health care. Bacteria and several fungal species have shown resistance to antibiotics used in treatment to current medications. Therefore, it is a considerable field of interest in the design and development of novel compounds with antimicrobial activity. Methods: The compounds bearing a heterocyclic ring play an imperative role among other organic compounds with pharmacological activity used as drugs in human for control and cure of various infections. Thiadiazoles containing nitrogen-sulfur atom as part of their cyclic structure which shown wide-ranging application as structural units of biologically active molecules and are very useful intermediates in Medicinal Chemistry. Results: The effectiveness of the thiadiazole nucleus was established by the drugs currently used for the treatment of various infections. 1,3,4-Thiadiazoles and some of their derivatives are widely studied because of their broad spectrum of pharmacological activities. Conclusion: In the present work, a series of 1,3,4-Thiadiazole derivatives were synthesized by cyclization of a group of various benzaldehyde with thiosemicarbazide in the presence of various reagent like FeCl3, HCHO by losing a molecule of water. These derivatives were found to possess prominent antimicrobial activity.

• Journal of Microbiology and Biotechnology
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• 제32권10호
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• pp.1299-1306
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• 2022

Six ansamycin derivatives were isolated from the culture broth of Streptomyces sp. KCB17JA11, including four new hygrolansamycins A-D (1-4) and known congeners divergolide O (5) and hygrocin C (6). Compounds 1-5 featured an unusual six-membered O-heterocyclic moiety. The isolation workflow was guided by a Molecular Networking-based dereplication strategy. The structures of 1-4 were elucidated using NMR and HRESIMS experiments, and the absolute configuration was established by the Mosher's method. Compound 2 exhibited mild cytotoxicity against five cancer cell lines with IC₅₀ values ranging from 24.60 ± 3.37 µM to 49.93 ± 4.52 µM.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2022년도 가을 학술논문 발표대회
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• pp.73-74
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• 2022

The corrosion inhibitive effect of a new hydrazone-based heterocyclic compound for steel in simulated concrete pore solution with 3.5 wt.% sodium chloride was investigated by experimental and computational techniques. Electrochemical studies, up to 30 days of immersion, and surface analysis (X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and scanning electron microscope (SEM)) were performed to assess the corrosion protection abilities of investigated compound for steel rebar. Results showed that adding the organic compound to the chloride contaminated concrete pore solution decreased the corrosion rate of the steel rebar thanks to the effective adsorption of inhibitor molecules. After 30 days of immersion of steel rebar in inhibited chloride contaminated synthetic concrete pore solution, the inhibition efficiency exceeded 80% at low concentration of 1 mmol/L. Computational studies by Density Functional based Tight Binding (DFTB) method revealed the formation of covalent bonds between the hydrazone molecule and the iron surface.

• 공업화학
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• 제26권2호
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• pp.234-238
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• 2015

모델 콜타르 유분 중에 함유된 질소고리화합물(NHC)의 분리를 메탄올과 포름아마이드 추출에 의해 비교했다. 원료로서는 4종류의 NHC (NHCs : 퀴놀린, 이소퀴놀린, 인돌, 퀴날딘), 3종류의 2환 방향족 화합물(BACs : 1-메틸나프탈렌, 2-메틸나프탈렌, 디메틸나프탈렌), 비페닐과 페닐에테르로 제조한 모델 콜타르 유분을 사용했다. 용매로서는 메탄올과 포름아마이드 수용액을 사용했다. 원료와 용매의 접촉 장치로서는 회분 교반기를 사용했다. 사용한 용매와 무관하게, 초기 용매 함수율의 감소와 평형조작 온도의 상승은 NHCs의 분배계수를 급격히 증가시켰으나, 역으로 BACs를 기준한 NHCs의 선택도를 감소시켰다. 초기 용매/원료의 체적비가 감소함에 따라 NHCs의 분배계수는 감소했으나, BACs를 기준한 NHCs의 선택도는 거의 일정했다. 동일한 실험조건에서, NHCs의 분배계수는 메탄올 추출이 포름아마이드 추출에 비해 약 3~5배 높았으나, BACs를 기준한 NHCs의 선택도는 역으로 포름아마이드 추출이 메탄올 추출에 비해 3~7배 높았다. 또한, NHCs의 용해력과 선택도의 밸런스에 NHCs의 추출처리속도를 부가하여 두 용매 추출법을 비교했다.

• Toxicological Research
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• 제31권3호
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• pp.255-264
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• 2015

Heterocyclic amines (HCAs) and acrylamide are unintended hazardous substances generated by heating or processing of foods and are known as carcinogenic and mutagenic agents by the animal experiments. A simple method was established for a rapid and accurate determination of 12 types of HCAs (IQ, MeIQ, Glu-P-1, Glu-P-2, MeIQx, Trp-P-1, Trp-P-2, PhIP, $A{\alpha}C$, $MeA{\alpha}C$, Harman and Norharman) and acrylamide in three food matrices (non-fat liquid, non-fat solid and fat solid) by isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS). In every sample, a mixture of internal standards including $IQ-d_3$, $MeIQx-d_3$, $PhIP-d_3$, $Trp-P-2-^{13}C_2-^{15}N$ and $MeA{\alpha}C-d_3$ was spiked for quantification of HCAs and $^{13}C_3$-acrylamide was also spiked for the analysis of acrylamide. HCAs and acrylamide in sample were extracted with acetonitrile and water, respectively, and then two solid-phase extraction cartridges, ChemElut: HLB for HCAs and Accucat: HLB for acrylamide, were used for efficiently removing interferences such as pigment, lipid, polar, nonpolar and ionic compounds. Established method was validated in terms of recovery, accuracy, precision, limit of detection, limit of quantitation, and linearity. This method showed good precision (RSD < 20%), accuracy (71.8~119.1%) and recovery (66.0~118.9%). The detection limits were < 3.1 ng/g for all analytes. The correlation coefficients for all the HCAs and acrylamide were > 0.995, showing excellent linearity. These methods for the detection of HCAs and acrylamide by LC-MS/MS were applied to real samples and were successfully used for quantitative monitoring in the total diet study and this can be applied to risk assessment in various food matrices.

• 한국식품영양학회지
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• 제17권3호
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• pp.313-321
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• 2004

Maillard reaction을 이용하여 제조한 여러 종류의 reaction meat flavor로부터 함유황 이원자고리 화합물을 분리, 농축한 다음 GC와 GC-MSD를 이용하연 함유황 이원자고리 화합물의 profile을 얻어 성분의 확인 및 정량분석을 시도하여 다음과 같은 결론을 얻었다. 1. Reaction meat flavor의 함유황 이원자고리 화합물의 profile을 조사한 결과 7종의 thiozole과 11종의 thiophene을 동정 할 수 있었으며, thiophene, thinzolidine, 4-methyl-5-thiazole ethanol이 주요 생성 화합물이었다. 2. 함유황 이원자고리 화합물의 경우 반응조건(온도, 시간)의 변화에 따라 생성성분의 종류에는 거의 차이가 없었지만 그 양에 있어서는 상당한 차이가 나타났고, 반응온도가 높을수록, 반응시간이 길수록 구조가 복잡한 함유황 이원자고리 화합물과 caramellike note를 갖는 함산소 이원자고리 화합물이 보다 많이 생성되었으며, 반대로 반응온도가 낮고 반응시간이 짧을수록 함유황이 원자고리 화합물의 생성이 비교적 적었다. 3. 수분함량 50%, 반응온도 10$0^{\circ}C$, 반응시간 2시간의 반응조건에서 thiophene과 thiazole 같은 비교적 구조가 단순한 함유황 이원자고리 화합물의 생성율이 가장 높았으며, reaction meat flavor의 발현을 위하여는 10$0^{\circ}C$ 이내의 온도에서 2시간을 넘기지 않고 반응시키는 것이 좋았다. 4. 수분함량이 낮으면 반응온도 및 시간을 낮고 짧게, 수분함량이 높을수록반응온도 및 시간은 높고 길게 반응시키는 등 수분함량은 반응온도 및 시간과 밀접한 관계에 있으므로 수분함량에 따라 반응조건을 변화시킴으로써 일정한 flavor profile을 계속하여 얻을 수 있었다. 이와 같이 원료를 단순화하여 reaction meat flavor를 제조한 다음 함유황 이원자고리 화합물을 추출, 분리, 농축하여 분석함으로써 향료산업 및 조미식품산업에서 reaction meat flavor의 생산에 필요한 하나의 방향을 제시할 수 있었다.

• 한국산학기술학회논문지
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• 제14권11호
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• pp.6000-6007
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• 2013

유기합성 과정에서 응용범위가 넓고 안정한 알코올류의 산화제에 대해 많은 연구가 진행 되고 있으며, 그중에서도 Cr(VI)-계열의 시약들이 산화제로 널리 이용되어 왔다. 그러므로 유기 용매에 잘 용해되고, 일차 알코올을 알데히드까지만 산화시키는 산화제의 합성과 그에 따르는 메카니즘 규명이 필요하게 되었다. Cr(VI)-헤테로고리 착물인 Cr(VI)-isoquinoline를 합성하여, 적외선 분광광도법(IR), 유도결합 플라즈마(ICP) 등으로 구조를 확인하였다. 또한 여러가지 용매 하에서 Cr(VI)-isoquinoline를 이용하여 벤질 알코올의 산화반응을 측정한 결과 유전상수(${\varepsilon}$) 값이 큰 용매 순서인 시클로헥센<클로로포름<아세톤$CH_3$, m-Br, m-$NO_2$)을 효과적으로 산화시켰다. 여기서 전자받개 그룹들은 반응 속도가 감소한 반면에 전자주개 치환체들은 반응속도를 증가시켰고, Hammett 반응상수(${\rho}$) 값은 -0.69(308K) 이였다. 그러므로 본 실험에서 알코올의 산화반응 과정은 먼저 크로메이트 에스테르 형성과정을 거친 후, 속도결정단계에서 수소화 전이가 일어나는 메카니즘임을 알 수 있었다.