• Bulletin of the Korean Chemical Society
• /
• v.23 no.4
• /
• pp.539-540
• /
• 2002

• Bulletin of the Korean Chemical Society
• /
• v.15 no.6
• /
• 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
• /
• v.3 no.2
• /
• 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
• /
• v.25 no.4
• /
• 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
• /
• v.9 no.3
• /
• pp.187-188
• /
• 1988

• Journal of the Korean Chemical Society
• /
• v.45 no.6
• /
• pp.549-554
• /
• 2001

For the development of new COX-2 inhibitor, novel compound were synthesized through induction an arylsulfonyl group to 1-position, an arylcarboxamidyl group to 2-position and an alkyl group to 4-position of L-proline. We started from 4-hydroxy-L-proline, the 4-methylphenylsulfonyl of 1-position was introduced through N-tosylation and the carboxylic acid group was protected by esterification. We sucessfully converted to a various derivatives 4b-d for O-alkyl-(or aralkyl)ation of 4-position using silver oxide as catalysis. The 4-alkyloxy-1-tosyl L-prolines 5b-d were synthesized through base-hydrolysis for the deprotection of carboxylic acid. Final compound 1,2,4-substituted pyrrolidines, 4-alkyloxy-2-phenylcarboxamidyl-1-tosyl pyrrolidines 6a-d were synthesized through the condensation of arylamine with 3 and 5b-d using DCC.

• Fibers and Polymers
• /
• v.1 no.2
• /
• 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.

• Journal of the Korean Chemical Society
• /
• v.59 no.6
• /
• pp.488-492
• /
• 2015

In this study, the effective preparation method of (S)-(+)-pranidipine, the active component of antihypertensive drug as a calcium channel blocker, was developed using optical resolution. The racemic monocarboxylic acid 5 obtained by the hydrolysis of (±)-pranidipine was mixed with optically active quinidine to form salts, and the insoluble diastereomeric salt was collected and successive treatment with base and acid furnished (R)-(-)-carboxylic acid 7. (S)-(+)-Pranidipine was prepared by esterification of this acid with cinnamyl alcohol, and the analysis by chiral HPLC showed 100% enantiomeric excess (ee). This process would be industrially very useful to prepare chiral (S)-(+)-pranidipine, since the use of strong base and anhydrous solvents, and ultra-low temperature condition were excluded in this process.

• KSBB Journal
• /
• v.26 no.3
• /
• 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.

• Membrane Journal
• /
• v.14 no.3
• /
• pp.240-249
• /
• 2004

Crosslinked PVA membranes were achieved by esterification between the hydroxyl groups of PVA and carboxyl group of sulfosuccinic acid (SSA). SSA containing sulfonic group was used as a chemical crosslinking agent as well as a donor of fixed anionic group ($-SO_3$H). The crosslinking density of membranes was controlled by SSA content and calculated using polar and non-polar solvent. The crosslinking density measured by using non-polar solvent such as xylene and benzene increases with SSA content. However, using the polar solvent such as water and methanol, the crosslinking density increases up to SSA content of 20 wt% and above the content decrease due to sulfonic acid groups. The crosslinked PVA membranes were studied in relation with water diffusion coefficient and mechanical property as well as proton conductivity and methanol permeability as a function of crosslinking density. These properties were all dependent on the effect of SSA content.