• Journal of the Korean Wood Science and Technology
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• 제31권6호
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• pp.31-39
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• 2003

The enzymatic isolation of residual lignins obtained from spruce and beech pulps (obtained by sulfite, kraft, ASAM and soda/AQ/MeOH pulping processes) and their characterization was described in previous publications. Here, the residual lignins have been submitted to potassium permanganate oxidation (KMnO₄ degradation), and 9 aromatic carboxylic acids (3 of them are dimeric) were identified after methylation with diazomethane by GC/MS. The analytical challenge during qantification by the internal standard methods was the partly high protein content of the samples, which resulted in elevated anisic acid yields in the degradation mixture of sulfite residual lignins. The results are compared with the KMnO₄ degradation of the corresponding MWLs and discussed in terms of S/G ratios and degrees of condensation. The latter was calculated as a quotient between the aromatic carboxylic acids derived from condensed and non-condensed lignin structures. Typical degradation patterns for the various processes have been observed. Among other parameter, the relative compositions between iso-hemipinic acid (which is for condensation in pos. 5 of the aromatic ring) and meta-hemipinic acid and 3,4,5-trimethoxyphthalic acid (both are for condensation in pos. 6 of the aromatic ring) was found to be process specific. Kraft and soda/AQ/MeOH residual lignins yielded higher amounts of iso-hemipinic acid. In contrast, the relative yields of meta-hemipinic acid and 3,4,5-trimethoxyphthalic acid (the latter in beech lignins) are higher in sulfite and particularly in ASAM residual lignin. In case of beech residual lignins the amount of acids originated from non-condensed syringyl type lignin units was surprisingly high. The condensation degree of residual lignins was shown to be generally higher than that of MWLs. This was especially true for the G units. ASAM residual lignin exhibited very high S/G ratios and degrees of polymerization. Causality between condensation degree and total yield of degradation products was demonstrated.

• 청정기술
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• 제28권4호
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• pp.331-338
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• 2022

본 연구의 목적은 열분해연료유(pyrolysis fuel oil, PFO)에 포함된 다환 방향족 탄화수소(polycyclic aromatic hydro, PAHs) 수소화 반응용 촉매로서 Pt(1wt%)/Kieselguhr 비드 촉매 및 펠렛 촉매를 제조하는 것이다. Trickle-bed 반응기에서 PFO-cut 수소화 반응을 통한 포화 고리 화합물(saturated cyclic compound)의 수율을 최대화하기 위한 최적의 반응 온도 및 수소/PFO-cut 유량비는 각각 250℃와 1800으로 결정하였다. PFO-cut의 공간속도(LHSV)가 감소할수록 포화 고리 화합물의 수율이 증가하였다. 펠렛 촉매와 비드 촉매의 수소화 반응 성능 차이는 크지 않았다. Kieselguhr 지지체를 성형한 후에 Pt를 담지한 촉매(AI 촉매)가 kieselguhr 분말에 Pt를 담지한 후에 성형한 촉매(BI 촉매)에 비해 수소화 활성이 높았으며, 이러한 경향은 펠릿 촉매와 비드 촉매에서 공통적으로 나타났다. 이는 AI 촉매의 Pt 활성점 수가 BI 촉매 보다 많기 때문이다. 본 연구에서 제조한 촉매 중에서 AI법으로 제조된 펠렛 촉매가 제조된 촉매 중 반응 활성이 가장 우수한 것을 확인하였다. PFO-cut 수소화 반응 생성물 중 C₈~C₁₅ 범위의 고리 화합물이 대부분을 차지했으며, C11 고리 화합물의 분포도가 가장 높았다. 수소화 반응과 더불어서 분해 반응도 함께 촉진되어 생성물의 탄소수 분포가 경질 탄화수소 쪽으로 이동함을 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.265-267
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• 2005

An efficient method of addition of trimethylsilyl cyanide to aldehydes by employing a zirconium complex as the catalyst has been described. A variety of aromatic, aliphatic, cyclic and heterocyclic aldehydes has been converted into corresponding trimethylsilyl ethers in excellent yield within short reaction time.

• 약학회지
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• 제22권2호
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• pp.83-86
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• 1978

A colorless sublime needles (A), $C_{10}H_{10}O_{4}$, mp$142~143\circ$ was isolated from the fresh flowers of Chrysanthemun sinense Sabine in 0.16% yield. Its ir, nmr and mass spectral data suggested that it may have an aromatic methylester structure. Hydrolysis of this substane with 10% sodium hydroxide solution yielded terephthalic acid and methanol. This substance was confirmed as dimethyl terephthalate by comparison of ir and nmr spectra, and TLC and GC behaviors of an authentic sample which was prepared from terephthalic acid by methylation. This is the first report that dimethly terephthalate was isolated in the Composite plants.

• Archives of Pharmacal Research
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• 제14권4호
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• pp.379-384
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• 1991

The Knoevenagal reaction of malononitrile and acetylacetone gave the acyclic product 3 which was separated in a good yield and identified. The reactivity of 3 towards some chemical reagents is studied. Thus, the reaction of 3 with aromatic aldehydes, hydrazines and cyanomethylene derivatives gave products 6-12. Reaction of 3 with benzenediazonium chloride gave the primidine derivative 14.

• Bulletin of the Korean Chemical Society
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• 제12권6호
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• pp.649-652
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• 1991

The reaction of primary aromatic amines with 1,7-heptanediol in the presence of a catalytic amount of ruthenium complex in dioxane at $180^{\circ}C$ for 24 hours gave the corresponding 1-substituted perhydroazocines in moderate yield.

• Bulletin of the Korean Chemical Society
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• 제9권5호
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• pp.322-324
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• 1988

Selective reduction of aldoximes and ketoximes with lithium borohydride in tetrahydrofuran was investigated. Thus, aldoximes and cyclic ketoximes such as hexanaldoxime, heptanaldoxime, cyclopentanone oxime and cyclohexanone oxime were reduced smoothly to the corresponding N-monosubstituted hydroxylamines at room temperature in 65-93% yield. The reduction of alicyclic ketoxime was very slow, requiring somewhat high reaction temperature ($65^{\circ}C$) for the complete reduction to give the hydroxnylamines. The reduction of aromatic oximes such as benzaldoxime and acetophenone oxime was very sluggish, giving a mixture of the corresponding hydroxylamines and amines at $65^{\circ}C$.

• Journal of Microbiology and Biotechnology
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• 제11권3호
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• pp.435-442
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• 2001

Poly(3-hydroxy-5-phenylvalerate) [P(3HPV)] was efficiently accumulated from 5-phenylvalerate (5PV) in Pseudomonas putida BM01 in a mineral salts medium containing butyric acid (BA) as the cosubstrate. A nove aromatic copolyester, poly(5 mol% 3-hydroxy-4-phenylbutyrate-co- 95 mol% 3-hydroxy-6-phenylhexanoate) [P(3HPB-co-3HPC)] was also synthesized from 6-phenylhexanoate (6PC) plus Ba. The two aromatic polymers, P(3HPV) and P(3HPB-co-3HPC), were found to be amorphous and showed different glass-transition temperatures at $15^{\circ}C$ and $10^{\circ}C$, respectively. When the bacterium was grown ina medium containing 20 mM 5PV as the sole carbon source for 140 h, 0.4 g/l of dry cells was obtained in a flask cultivation and 20 wt% of P(3HPV) homopolymer was accumulated in the cells. However, when it was grown with a mixture of 2 mM 5PV and 50 mM BA for 40 h, the yield of dry biomass was increased up to 2.5 g/l and the content of P(3HPV) in the dry cells was optimally 56 wt%. This efficient production of P(3HPV) homopolymer from the mixed substrate was feasible because BA only supported cell growth and did not induce any aliphatic PHA accumulation. The metabolites released into the PHA synthesis medium were analyzed using GC or GC/MS. Two $\beta$-oxidation derivatives, 3-phenylpropionic acid and trans-cinnamic acid, were found in the 5V-grown cell medium and these comprised 55-88 mol% of the 5PV consumed. In the 6PC-grown medium containing Ba, seven ${\beta}$-oxidation and related intermediates were found, which included phenylacetic acid, 4-phenylbutyric acid, cis-4-phenyl-2-butenoic acid, trans-4-phenyl-3-butenoic acid, trans-4-phenyl-2-butenoic acid, 3-hydroxy-4-phenylbutyric acid, and 3-hydroxy-6-phenylhexanoic acid. Accordingly, based on the metabolite analysis, PHA synthesis pathways from the two aromatic carbon sources are suggested.

• 환경위생공학
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• 제15권4호
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• pp.98-104
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• 2000

Commercial rubber(IR, NR, BR), SBR, and tire were degraded by thermal degradation process. The oil yield of rubbers and tire ranges about 37~86%, it was increased with increase of operation temperature in pyrolysis. And the yield of pyrolytic oil was increased with increase of heating rate. The maximum oil yields of IR, NR, BR, SBR, and tire were 80, 73, 83, 86 and 55% each at $700^{\circ}C$ with a heating rate of $20^{\circ}C$/min, respectively. The pyrolytic oil components were consisted of about 50 aromatic compounds. The calorific value of purolytic oil of commercial rubber, SBR, and tire was measured by calorimeter, it was 39~40 kJ/g. The BET surface area of pyroblack was $47~63m^2/g$. The optimum condition of pyrolysis was operating temperature of $700^{\circ}C$ with heating rate of $20^{\circ}C$. Therefore, the pyrolytic oil and pyroblack are possible to alternative fuel and carbon black.

• Carbon letters
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• 제6권3호
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• pp.173-180
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• 2005

In this study, AR (aromatic resin) pitch was employed as the matrix-precursor for carbon/carbon composite because it exhibits much higher coke yield than coal tar pitch. As a result, a fabrication process of carbon/carbon composites can be shortened. It has been known that the pitches may cause swolling problem during the carbonization process. In order to restrain the swelling occurrence, a small quantity of carbon black was added to the AR pitch. Due to addition of carbon black the swelling was decreased largely and the perform can be infiltrated with the AR pitch. The densification efficiency of the performs was compared with various matrix-precursors. The coke yield of matrixprecursors, the morphology and the degree of graphitization of carbon matrix were analyzed.