• Textile Coloration and Finishing
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• v.7 no.4
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• pp.61-73
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• 1995

Inorganic salts have negative or positive effects on the rates of many chemical reactions and also the rates of acidic and alkaline hydrolysis of carboxylic esters. The direction of salt effects on the hydrolysis of ester depends on the charge of esters. It is expected that the rate of the alkaline hydrolysis of Poly(ethylene terephthalte)(PET), polymeric solid carboxytic polyester with carboxyl end group at the polymer end, is also influenced by inorganic salts. In the present work, to clarify the effect of divalent cations on the alkaline hydrolysis of PET, many salts with divalent cations like $MgCl_{2},CaCl_{2},SrCl_{2},BaCl_{2},$ were added to the aqueous alkaline solutions. Then PET was hydrolyzed with aqueous NaOH solution having many salts under various conditions. Some conclusions obtained from the experimental results were summarized as follows. Many salts with various divalent cations increased or decreased the reaction rate of alkaline hydrolysis of PET depending on their electrophilicity, hydration property, ability of ion pair formation, solubility, and the degree of interactions between divalent cations and anions, etc. The hydrolysis was interrupted in the order of $Ca^{+2} and was generally accelerated in the order of $Ba^{+2}. It was inferred from the increase in ΔS$^*$and the decrease in the ΔG$^*$that the divalent cations $Sr^{+2}$ and $Ba^{+2}$attracted by PET increased the collision frequency between carbonyl carbon and $OH^{-}$ion and then accelerated the reaction rate. $Mg^{+2}$and $Ca^{+2}$decreased the reaction rate because of their strong interaction with $OH^{-}$.

• Journal of Food Hygiene and Safety
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• v.15 no.2
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• pp.144-150
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• 2000

The present study was peformed to determine the hydrolysis rate constants and degradation products of phosphamidon and proffnofos by the OECD method. Hydrolysis rate constants of phosphamidon in pH 4, pH 7, and pH 9 buffer solutions at 25 and 40$^{\circ}$C were 0.0020, 0.0022, 0.0049 and 0.0040, 0.0050, 0.0150, respectively. Hydrolysis rate of phosphamidon was accelerated by temprerature change under same pH conditions, and half-life of phosphamidon in pH 9 at 40。C was 3 times faster than that at 25。C. Hydrolysis rate of phosphamidon in alkaline solution(pH 9) was 2~4 times faster than that in acidic solution(pH 4) and neutral solution(pH 7) under same temperature. Hydrolysis rate constants of profenofos in pH 4, pH 7, and pH 9 buffer solutions at 25 and 40。C were 0.0022, 0.0047, 0.0860 and 0.0035, 0.0086, 0.1245, respectively. Hydrolysis rate of profenofos was accelerated by temprerature change under same pH conditions. Hydrolysis rate of profenofos in alkaline solution(pH 9) was 15~40 times faster than in acidic solution(pH 4) and neutral solution(pH 7) under same temperature condition, and half-life of profenofos was very fast within 8 hours. The hydrolysis rate of profenofos was faster than that of phosphamidon. In order to identify hydrolysis products, the extracts of degradation products were analyzed by GC/MS. The mass spectra of hydrolysis products of phosphamidon were at m/z 153 and 149, those of the profenofos were at m/z 208 and 240, respectively. The hydrolysis products of phosphamidon were O, O-dimethyl phosphate(DMP) and N, N-diethylchloroacetamide, and those of profenofos were 4-bromo-2-chlorophenol and O-ethyl-S-propyl phosphate.

• Journal of Ginseng Research
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• v.45 no.2
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• pp.246-253
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• 2021

Background: Ginseng is one of the most valuable herbal supplements. It is challenging to perform quality control of ginseng products due to the diversity of bioactive saponins in their composition. Acid or alkaline hydrolysis is often used for the structural elucidation of these saponins and sugars in their side chains. Complete transformation of the original ginsenosides into their aglycones during the hydrolysis is one of the ways to determine a total saponin group content. The main hurdle of this approach is the formation of various by-products that was reported by many authors. Methods: Separate HPLC assessment of the total protopanaxadiol, protopanaxatriol and ocotillol ginsenoside contents is a viable alternative to the determination of characteristic biomarkers of these saponin groups, such as ginsenoside Rf and pseudoginsenoside F₁₁, which are commonly used for authentication of P. ginseng Meyer and P. quinquefolius L. samples respectively. Moreover, total ginsenoside content is an ideal aggregated parameter for standardization and quality control of ginseng-based medicines, because it can be directly applied for saponin dosage calculation. Results: Different hydrolysis conditions were tested to develop accurate quantification method for the elucidation of total ginsenoside contents in herbal products. Linearity, limits of quantification, limits of detection, accuracy and precision were evaluated for the developed HPLC-MS method. Conclusion: Alkaline hydrolysis results in fewer by-products than sugar elimination in acidic conditions. An equimolar response, as a key parameter for quantification, was established for several major ginsenosides. The developed approach has shown acceptable results in the analysis of several different herbal products.

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.338-343
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• 1988

Selected kinetic parameters and degree of hydrolysis(DH) were measured using commercial proteases(trypsin, alcalase and pronase) to study the affinity of these enzymes to 7S and 11S soy proteins. Electrophoretic patterns of the hydrolysates were also investigated. In general, the order of affinity between the proteins and the proteases was 11S(protein-rich fraction)and 7S PRF for unheated proteins, and 7S PRF and 11S PRF for preheated proteins. Substrate inhibition was present at a substrate concentration of 1.5% or higher when preheated protein was used as the substrate. The maximum DH values of alcalase were obtained from 7S PRF(60%) and 11S PRF(80%) at 1 hr hydrolysis, respectively. Trypsin hydrolyses did not affect 11S soy protein but the acidic subunits in contrast to alcalase and pronase hydrolyses which changed almost all subunits. Alcalase hydrolysis induced distinct changes on 2S soy protein.

• Journal of Microbiology and Biotechnology
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• v.9 no.2
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• pp.163-167
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• 1999

An acidic polysaccharide H-III was extracted from fruiting bodies of Lyophyllum shimeji with hot water. Acid hydrolysis and gas chromatography analysis showed that the polysaccharide was almost exclusively composed of glucose with a very small amount of mannose and galactose. Uronic acid of 8.36% was also detected in H-Ill. Its molecular weight was estimated to be $1{\times} 10^6 Da.\;By\;^{13}C-NMR$ analysis, some repeating units of disaccharide were detected in the polymer H-III. The polysaccharide showed a strong mitogenic activity in a dose-dependent manner.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.32 no.1
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• pp.72-78
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• 2000

The major cause of paper deterioration is the acid-catalyzed hydrolysis of the cellulose in paper fibres. The deacidification of paper reduced the rate of this deterioration, and it has been reported to extend the useful life of acidic paper by three to five times. It has been recognized the need for an effective method of deacidifying large quantities of books and documents. T도 review of the current state of deacidification technology has been published recently. The paper points to the immediate need for a cost-effective and reliable method to save the millions of books that prish every year. It was tried to deacidify by the gaseous ethanolamine for solving with the above the problem. Acidic paper was treated with the monoethanolamine, diethanolamine, triehtanolamine. It result, it was found that the rate of deacidification was in caused very little grightness and fold endurances. For solving this problem, it was carried with deacidify by combination treatment of the various gaseous ehtnaloamines. In result, decreasing of brightness and fold endurance is reduced.

• Journal of Pharmaceutical Investigation
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• v.18 no.3
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• pp.99-105
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• 1988

Inclusion complex formation of furosemide with ${\beta}-cyclodextrin({\beta}-CyD)$ in solid state was confirmed by X-ray diffractometry, IR spectroscopy and differential scanning calorimetry (DSC). The solid complexes of ${\beta}-CyD$ with furosemide in molar ratio of 2 : 1 were prepared by solvent evaporation method. The photodegradation of furosemide in alkaline solution under the light and the hydrolysis of furosemide in acidic solution were not inhibited by complex formation with ${\beta}-CyD$. However, the bioavailability of furosemide was improved by complex formation with ${\beta}-CyD$ after oral administration to rats.

• Journal of Ginseng Research
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• v.22 no.3
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• pp.205-210
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• 1998

Glucosidic bonds at the C20 position of the sapogenins were hydrolyzed easily in the lower pH, higher temperatures and longer times to give prosapogenins and sugars. The glucosidic bond of saponin at the C3 of ginsenoside-Rb1, which is secondary carbon, was relatively stable due to the low electron density of -0.2. But the bond of saponin at the C20 position, which is tertiary carbon with the relatively high electron density of -0.3, was liable to be hydrolyzed even in weakly acidic solution by the increase of heating time. On the other hand, red ginseng contained 13.34 mg/g of citric acid, 8.78 mg/g of malonic acid, 3.70 mg/g of oxalic acid, 2.13 mg/g of malic acid and 0.44 mg/g of succinct acid. Ginseng saponins were very stable in ginseng extract neutralized with sodium carbonate or sodium bicarbonate corresponding to the equivalent amount of the total organic acid in the red ginseng.

• YAKHAK HOEJI
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• v.40 no.3
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• pp.300-305
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• 1996

The base-induced elimination of N-protected 2-(bromomethyl)pyrrolidines 12a-c with KHMDS in THF at -78$^{\circ}C$ for 1h gave exocyclic enamines 13a-c. The acidic catalyzed pr otonation on ${\beta}$-carbon atom of 2-(methylene)pyrrolidines 13a-c with $H_3PO_4$ formed endocyclic N-iminium intermediates 14(or 15). Nucleophilic attack of alpha-carbon atom and hydrolysis of N-iminium ion gave carbocationic adduct (aminoalcohol) 16 from which 5-amino-2-pentanones 17a-c were formed after deprotonation.

• Journal of the Korean Chemical Society
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• v.34 no.1
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• pp.102-107
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• 1990

The reaction of thiazoline-azetidinone (7) with $I_2$ in $CH_2Cl_2-H_2O$ gave directly 3-iodo-3-methylcepham (4). A phase transfer catalyst considerably increased the reaction rate. Similar to the hydrolysis of thiazoline-azetidinone (7) under a weak acidic condition, thiazole (10) was given as major product in the treatment with 0.1 eq. of iodine. The difference between cyclization reaction and hydrolysis could be explained in terms of solvents, the amount of iodine and the nature of thiazoline-azetidinones (7).