• Archives of Pharmacal Research
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• 제29권10호
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• pp.840-844
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• 2006

For the exploration of pharmacophoric moiety of malloapelta B (1) possessing the inhibitory activity of $NF-{\kappa}B$ activation, structural variation of ${\alpha},{\beta}-unsaturated$ carbonyl motif was attempted. 1 was reduced by catalytic hydrogenation, sodium borohydride, and lithium aluminumhydride. Catalytic hydrogenation with 30 psi or 15 psi of $H_2$ gas of 1 generated 8-butyl-5,7-dimethoxy-2,2-dimethylchroman (2) and 1-(5,7-dimethoxy-2,2-dimethylchroman-8-yl)butan-1-one (3), respectively. Reduction with sodium borohydride occurred at the double bond of ${\alpha},{\beta}-unsaturated$ ketone of 1 to give 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)butan-1-one (4). Reduction of 1 with lithium aluminumhydride and then quenched with methanol and water produced unexpected products, 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-methoxy-1-butene (5) and 1-(5,7-dimethoxy-2,2-dimethyl-2H-chromen-8-yl)-3-hydroxy-1-butene (6). These are formed from the isomerization of initial product 9 through the continuous conjugate carbocation intermediate 11. Addition of ethylmagnesium bromide and dimethyl malonate anion to 1 gave the conjugate adducts 7 and 8. Ethylmagesium bromide and sodium borohydride reduction unusually gave the conjugate addition due to steric congestion around carbonyl group of 1. Compound 2 exhibits the reduced inhibitory activity against $NF-{\kappa}B$ activation and the others do not show the activity. Therefore ${\alpha},{\beta}-unsaturated$ carbonyl group of 1 should be important for its inhibitory activity.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2006년도 PAN PACIFIC CONFERENCE vol.2
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• pp.337-347
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• 2006

Papers made from unbleached and bleached bagasse chemimechanical pulp were chemically modified by acetylation. The effects of irradiation on unbleached and bleached also reduced papers of bagasse chemimechanical pulp before and after acetylation were investigated in this study. Chemimechanical pulp was prepared from bagasse and then bleached with hydrogen peroxide. Unbleached and hydrogen bleached pulps were reduced by Sodium borohydride in different procedures. Paper sheets were prepared from pulps and then acetylated using a technical grade of acetic anhydride. Accelerated photo-aging was run on the samples using fluorescent lamps to verify photo-stability of paper sheets before and after pretreatments. Brightness reversion (as Post-color number) and other optical properties of the paper sheets were measured. Efficient inhibition of photo-yellowing of papers made from bagasse CMP was achieved by acetylation. The acetylated unbleached CMP was noticeably photo-bleached during irradiation. Sodium borohydride reduction followed by acetylation had the same effect as acetylation alone at the same degree of reaction time and reductive treatment did not affect the yellowing rate to any great extent. The pre-reduced, acetylated unbleached papers were, however, not brightened during irradiation. Calculation done by Kubelka-Munk equation showed that reductive treatment had little effect in reducing the photo-yellowing of paper made from CMP pulp; a small stabilization effect was observed in the case of bleached CMP, while unbleached CMP was slightly more prone to discolor in the later phase of photo-reversion. The improved stability towards light may was closely related to the decrease in the phenolic hydroxyl content as a result of blocking by acetyl groups during treatment with acetic anhydride. The results support the hypothesis that phenolic hydroxyl has an important role in the process of photo-reversion of high-yield pulps. The results obtained in this study demonstrate that the acetylation of paper manufactured from peroxide bleached Bagasse CMP significantly retards light-induced discoloration. The inhibition of yellowing is connected with a decrease in the phenolic hydroxyl content of both unbleached and peroxide bleached papers.

• 대한화학회지
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• 제37권7호
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• pp.648-654
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• 1993

$[M(cyclam)X_2]Y(M=Co^{3+},\;Fe^{3+},\;Mn^{3+}\;:\;X=Cl-^,\;Br^-,\;NCS^-\;:\;Y=Cl^-,\;Br^-,\;NCS^-),\;[Co(trans-14-diene)X_2]Y(X=Cl^-,\;Br^-\;:\;Y= ClO_4^-)$ 및 $[Co(trans-14-diene)](ClO_4)_2$ 착이온은 sodium borohydride 하에서 산소를 활성화시킬 수 있었다. 활성화된 산소에 의한 2,4-di-tert-butylphenol 과 2,6-di-tert-butylphenol 산화반응의 생성물질을 각각 2,4-tert-butyl-1,6-benzoquinone(BQ) 와 3,5,3',5'-tetra-tert-butyldiphenoquinone(DPQ) 이었다. BQ와 DPQ 생성반응에서 포화 거대고리 리간드 착물인 $[Co(cyclam)X_2]Y$은 불포화 거대고리착물 $[Co(trans-14-diene)X_2]Y$에 비하여 더 효과적인 촉매제이었다. 촉매로 작용한 Co(III)-거대고리착물과 산소간의 몰 결합비$(O_2/M)$는 1/1이었고, $[M(cyclam)Cl_2]Cl(M=Fe(III)$, Mn(III))에서는 이들 비가 1/2이었다. 반응(10)과 (2)에서 산소분자의 활성종은 Co(III) 거대고리착물이온과 $[M(cyclam)Cl_2]Cl(M=Fe(III)$, Mn(III))에서 각각 superoxolike$({O_2}^-)$와 peroxolike$({O_2}^{2-})$로 가정하였다.

• Korean Chemical Engineering Research
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• 제48권3호
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• pp.322-326
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• 2010

수소발생용으로 사용되는 $NaBH_4$ 수용액의 저장과정 중에 $NaBH_4$ 안정성에 대해 연구하였다. $NaBH_4$의 안정성을 증가시키기 위해 NaOH와 KOH를 사용하였으며, $NaBH_4$의 저장 중 가수분해반응에 미치는 알칼리와 $NaBH_4$ 농도, 온도 그리고 저장 용기 재질의 영향을 실험하였다. 알칼리농도가 증가할수록 $NaBH_4$가 수용액 중에서 안정화되기 때문에 수소발생 속도가 감소하였다. $NaBH_4$ 농도를 10에서 15 wt%로 증가시켰을 때 안정성이 감소하다 15 wt% 이상으로 농도를 증가시켰을 때는 pH의 증가에 의해 안정성이 증가하였다. $NaBH_4$ 농도를 25 wt%, NaOH 3.0 wt%일 때 수소발생 활성화 에너지 값은 115.1 kJ/mol 로 촉매를 사용했을 때보다 활성화 에너지 값이 1.5~4.0배 높았다. 유리나 스텐리스-스틸에 저장된 $NaBH_4$ 용액의 안정성이 플라스틱에 저장된 $NaBH_4$ 용액의 안정성보다 더 높았다.

• 대한화학회지
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• 제20권1호
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• pp.59-72
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• 1976

수소화붕소아연의 선택환원성을 조사하기 위하여 대표적 유기화합물 54종을 택하여 수소화붕소 아연과 일정한 조건 (THF 용액, 실온, 수소화이온의 농도 : 0.5M, 유기화합물의 농도 : 0.125M)하에서 반응시켜 대략의 반응속도와 정량관계를 알아보았다.

• Bulletin of the Korean Chemical Society
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• 제27권5호
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• pp.765-768
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• 2006

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2007년도 춘계학술대회 논문집
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• pp.727-728
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• 2007

• Bulletin of the Korean Chemical Society
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• 제35권1호
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• pp.305-308
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• 2014

• Bulletin of the Korean Chemical Society
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• 제24권1호
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• pp.141-143
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• 2003

• Bulletin of the Korean Chemical Society
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• 제15권4호
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• pp.273-273
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• 1994