• Bulletin of the Korean Chemical Society
• /
• 제23권4호
• /
• pp.539-540
• /
• 2002

• Bulletin of the Korean Chemical Society
• /
• 제15권6호
• /
• pp.448-452
• /
• 1994

2-Hydroxymethyl-2,5-dihydrothiophene 1,1-dioxide (1) was prepared from thiophene-2-carboxylic acid by consecutive reactions involving the Birch reduction, esterification, reduction with lithium aluminum hydride, and oxidation with Oxone$^{\circledR}$. The esterification of alcohol 1 with various unsaturated carboxylic acids provided the precursors 8 for the intramolecular Diels-Alder reaction. The cheletropic expulsion of sulfur dioxide from the esters 8 followed by intramolecular Diels-Alder reaction furnished bicyclic ${\gamma}$-and ${\delta}$-lactones.

• Bulletin of the Korean Chemical Society
• /
• 제3권2호
• /
• pp.70-76
• /
• 1982

Synthetic utility of 1-fluoro-2,4,6-trinitrobenzene (FTNB) as a condensing agent was investigated. The use of FTNB and DMAP was found to be very effective for direct esterification of carboxylic acids with alcohols or thiols. However, this system was not very effective for macrolactonization. Reaction of 2,4,6-trinitrophenyl esters with several nucleophiles was investigated briefly. Plausible reaction mechanisms of esterification are presented. It seems that the reaction proceeds via the intermediacy of 2,4,6-trinitrophenyl esters by initial formation of 2',4',6'-trinitrophenyl-4-dimethylaminopyridinium salt from which the trinitrophenyl group is transferred to the carboxylic acid.

• Bulletin of the Korean Chemical Society
• /
• 제25권4호
• /
• pp.501-505
• /
• 2004

Esterification of aliphatic or aromatic carboxylic acids with alcohols using 2-(4-nitrobenzenesulfonyl)-4,5-dichloropyridazin-3(2H)-one (3) in the presence of base in organic solvents gave the corresponding esters in excellent yields

• Bulletin of the Korean Chemical Society
• /
• 제9권3호
• /
• pp.187-188
• /
• 1988

• 대한화학회지
• /
• 제45권6호
• /
• pp.549-554
• /
• 2001

새로운 COZ-2저해제를 개발하기 위하여 4-hydroxy L-proline의 1-위치에 arylsulfonyl기 2-위치에 arylcarboxamidyl기, 그리고 4-위치의hydroxy에 alkyl기를 도입한 새로운 후보 화합물을 합성하였다. 4-Hydroxy L-proline 1을 출발 물질로 하여 N-tosylation으로 1-위치에 4-methylphenylsulfonyl기를 도입하였고 esterification으로 carboxylic acid를 protection하였다. 4-위치의 O-alkyl-(or aralkyl)ation을 위해서 촉매로 silver oxide를 사용하여 다양한 유도체 4b-d로 전환시키는 데 성공하였다. Carboxylic acid기의 deprotection을 위해서 간편한 base-hydrolysis의 과정을 거쳐 4-alkyloxy-1-tosyl L-prolines 5b-d를 얻었다. 최종 목적 화합물인 1,2,4-치환된 pyrrolidine derivatives, 4-alkyloxy-2-phenylcarboxamidyl-1-tosyl pyrrolidines 6a-d 4종은 DCC를 사용하여 3 및 5b-d와 aniline과의 축합 반응으로 합성하였다.

• Fibers and Polymers
• /
• 제1권2호
• /
• pp.116-121
• /
• 2000

It has been considered that malic acid, $\alpha$-hydroky succinic acid, could not form crosslinks in the cellulosic materials unless activated by other polycarboxylic acids such as butanetetracarboxylic acid or citric acid because there are only two carboxylic acids per molecule available fur the formation of one anhydride intermediate. However we found that the dicarboxylic malic acid with sodium hypophosphite catalyst without the addition of other crosslinkers was able to improve wrinkle resistance of cotton up to $294^{\circ}$(dry WRA) and $285^{\circ}$ (wet WRA), which is a measure of crosslinking level in cotton. $^1$H FT-NMR, FT-IR and GPC analysis indicated the in-situ formation of an trimeric $\alpha$, $\beta$-rnalic acid with a composition of 1:3 through the esterification between hydroxyl group and one of carboxylic groups in malic acid during curing. The crosslinking of cotton was attributed to the trimeric $\alpha$, $\beta$-malic acid, a tetracarboxylic acid, which can form two anhydride rings during curing. The influence of crosslinking conditions such as concentrations of malic acid and catalyst, pH of the formulation bath, and curing temperature were investigated in terms of imparted wrinkle resistance and whiteness. The addition of reactive polyurethane resin in the formulation slightly increased the mechanical strength retention of crosslinked fabric coupled with additional increase in wrinkle resistance.

• 대한화학회지
• /
• 제59권6호
• /
• pp.488-492
• /
• 2015

본 연구에서는 칼슘채널 차단제로서 항고혈압 작용을 가진 (S)-(+)-pranidipine의 광학 분할에 의한 효과적인 제조방법을 제시하였다. (±)-Pranidipine을 가수분해시켜 얻은 monocarboxylic acid 5의 라세미 혼합물에 광학 활성이 있는 quinidine을 첨가하여 염을 형성한 다음 불용성 부분입체이성질체 염을 여과하고 염기와 산으로 처리하여 (R)-(-)-carboxylic acid 7을 분리하였고 이 carboxylic acid를 cinnamyl alcohol과의 에스터화 반응에 의해 (S)-(+)-pranidipine을 합성하였다. 이 화합물의 거울상 초과량(enantiomeric excess, ee)을 카이랄 HPLC로 분석한 결과 100% ee 값이 얻어졌고, 합성 과정에서 강염기 사용과 무수 조건 및 초저온 조건을 배제하였는바 이는 산업상 매우 유용한 개량방법이라 하겠다.

• KSBB Journal
• /
• 제26권3호
• /
• pp.193-198
• /
• 2011

Polyester was prepared through the esterification reaction between watsepaper liquefied by ethylene glycol and carboxylic acid. Liquefaction was carried out at the previously determined condition of 100 minutes, $160^{\circ}C$, and 3% sulfuric acid, and the hydroxyl value of the liquefied product was 411 mg KOH/g. In order to remove bubbles produced during the curing step, the method to introduce a slight nitrogen stream into reaction vessel and/or the method to preheat a polyester film at $85^{\circ}C$ before curing step were used alone or in combination. But if curing temperature was $130^{\circ}C$, simple method to cure a film for 5 hours at $130^{\circ}C$ without using both methods was found to be most effective. The polyesters prepared with various carboxylic acids showed significant different physical properties, and maleic acid was best among them. Also, the effect of reaction time and temperature, C/H (carboxyl group/hydroxyl group) ratio, and type of additive on the crosslinkage of polyester was investigated. Lithium hydroxide or citric acid as additive was used to enhance the crosslinkage of polyester and citric acid was proved to be much more effective than lithium hydroxide. The effect of reaction temperature on the crosslinkage was marginal, but the crosslinkage decreased above $130^{\circ}C$. The crosslinkage was 86% when the polyester was prepared at an optimum condition such as $130^{\circ}C$ and 15 minutes of reaction condition, 1.5 of C/H ratio, $130^{\circ}C$ and 5 hours of curing condition, and 10% addition of citric acid.

• 멤브레인
• /
• 제14권3호
• /
• pp.240-249
• /
• 2004

본 연구에서는 polyvinylalcohol(PVA)의 hydroxyl 작용기와 sulfosuccinic acid (SSA)의 carboxylic acid 작용기의 반응을 통하여 열가교된 PVA막을 제조하였다. 설폰산기를 함유한 SSA는 PVA 매트릭스에 대한 가교제의 역할뿐만 아니라 수소이온의 전도도를 높이는 역할 모두를 수행하였다. PVA의 가교도(degree of crosslinking)는 SSA의 함량으로 조절하였고 가교밀도(crosslinking density)는 극성 및 비극성 용매를 이용하여 계산하였다. Xylene 및 benzene과 같은 비극성 용매를 사용한 경우 가교밀도는 SSA함량에 따라 증가하였다. 그러나, 물과 methanol과 같은 극성 용매를 사용한 경우 가교밀도는 SSA함량 20%까지 증가하다가 그 이상의 함량에서는 설폰산기의 영향으로 감소하였다. 가교도와 확산계수, 기계적 물성 및 전도도, 메탄올 투과도 등에 대한 PVA막의 특성을 평가하였고 이들 특성은 SSA함량에 의존하였다.