• Archives of Pharmacal Research
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• 제23권2호
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• pp.99-103
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• 2000

Acid and base catalyzed intramolecular cyclizations of N-benzoylthioureidoacetal, contain-ing four functional groups adjacent to thiourea such as benzocarbamoyl, acetal, thioure and amide, were investigated. The condensation reaction of N-benzoyl thiocarbamoylgly-cine amide in the presence of 10% aqueous NaOH provided 1-(2,2-dimethoxy)ethyl-imi- dazolidine-2-thione exclusively. In the presence of pyridine, it was transformed to 2- thiohydantoin. N-Benzoyl thiocarbamoyl glycine amide was completely transformed to an iminothiazolidine exclusively in the presence of Lewis acid such as borontrifluoride ether-ate or trimethylsilyl iodide. 1-(2,2-Dimethoxy)ethyl-imidazolidine-2-thione was transformed to imidazole[2,1-b]thiazole and pyrazino[5,1-a]imidazole in the presence of $BF_3$.$ET_2$O and formic acid, respectively.

• 한국임상수의학회지
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• 제28권4호
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• pp.352-356
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• 2011

Abstract: This study was aimed to diagnose acid-base disorders of dogs with canine parvoviral enteritis (CPE) and data to establish a rational fluid therapy regimen for patients with CPE. A total of 43 dogs which had clinical signs of CPE and had detected canine parvovirus by polymerase chain reaction, were bled anaerobically from jugular vein at the time of admission. Blood chemical test, determination of electrolytes and blood gas analysis were conducted, and calculated values were obtained from each measured items. The values of blood chemical and electrolytes of dogs with CPE were various depending on the degree of clinical signs, and these tests were not specific to diagnose for CPE. Hypochloremia (20.9%), hyperchloremia (11.6%), hypokalemia (7.0%), hyperkalemia (11.6%), hyponatremia (9.3%) and hypernatremia (18.6%) were diagnosed as abnormalities of electrolytes from 43 dogs with CPE. The 29 out of 43 dogs (67.4%) were metabolic acidosis and 3 dogs (7.0%) were metabolic alkalosis. The acid-base status of 11 dogs out of 43 dogs (25.6%) was normal.

• 한국세라믹학회지
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• 제32권7호
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• pp.783-792
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• 1995

Sol-Gel derived ferroelectric PZT thin films were fabricated on ITO/Glass and Si/SiO2 substrates. In order to investigate the effect of catalysts on the densification and crystallization of PZT thin films, a nitric acid or ammonium hydroxide was added to the PZT stock solution at the state of partial hydrolysis reaction. The measured pH for a stable PZT sol was 5.2~9.3. In case of an acid-catalyzed PZT sol, a highly condensed particulate PZT sol was formed by accelerating the hydrolysis reaction. But weakly branched polymeric PZT sol was formed with a base-catalyzed condition. The difference in densification behavior was not found in the pH range of added catalyst, but the refractive index of PZT thin film was increased rapidly as the annealing temperature increased. The PZT thin film annealed at 54$0^{\circ}C$ for 10 min was fully densified and its refractive index was above 2.4. When the annealing temperature increased, the transition from the pyrochlore phase to perovskite appeared at 54$0^{\circ}C$. The base-catalyzed PZT thin film suppressed to form the pyrochlore phase and proceeded effectively to convert the perovskite phase. This was due to the formation of polymeric molecular structure by controlling the hydrolysis and condensation reaction through the additiion of the ammonium hydroxide.

• 한국응용과학기술학회지
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• 제27권4호
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• pp.522-530
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• 2010

We developed functional synthetic lubricant for internal combustion engine oil, which would improve engine oil performance for internal combustion engine and extend engine life. We made base oil by synthesizing nonanoic acid, 1.1.1-trimethylol propane (which has good bio-degradability) and pentaerythrytol ester. We synthesized catalyst using p-toluene sulfonic acid 0.15 wt% and coloring-prevention agent hypo-phosphorus acid 0.18 wt% at 180-$190^{\circ}C$. Reaction temperature was increased at the rate of $10^{\circ}C$ for every 1 hour. When acid value reached below 3, reaction was completed. After cooling and deoxidization, we washed it by distilled water two times. After dehydration and filtering, we obtained trimethylol propane tripelargonate (TMTP) and pentaerythrytol tetrapelargonate (PETP) at yields of 96 % and 98 % respectively.

• Journal of Pharmaceutical Investigation
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• 제22권1호
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• pp.23-31
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• 1992

A novel O-diethylaminoethyl chitosan (DEAE-chitosan) was synthesized via Schiff's reaction between chitosan and benzaldehyde. $C_2$ amino group was protected via Schiffs base reaction with benzaldehyde to form N-benzylidene chitosan. After reaction with diethylaminoethyl chloride, Schiffs base was removed by reacting O-diethylaminothyl-N-benzylidene chitosan and hydrochloric acid. Tensile strength of DEAE-chitosan was improved due to the incorporation of bulky side group in $C_6$ position of chitosan. DEAE-chitosan showed a pH-dependent swelling characteristics. Release rate of riboflavin was dependent on the water content of DEAE-chitosan that is a function of crosslinking degrees.

• 한국응용과학기술학회지
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• 제7권2호
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• pp.33-40
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• 1990

The Kinetics of the addition of benzalacetophenone derivatives was investigated by ultraviolet spectrophotometery in 5% dioxane $H_2O$ at $50^{\circ}C$. A rate equation was obtained in wide range of pH. The substituent effects on benzalacetophenone derivatives were studied, and addition were facilitated by electron attracting groups. The final product was benzalacetophenone-${\beta}$-thioglycolic acid synthesized by the addition of thioglycolic acid to benzalacetophenone. On the base of the rate equation, substituent effect, general base effect and final product, the plausible addition mechanism was proposed: Below pH 9.0, only neutral thioglycolic acid molecule was added to the carbon-carbon double bond, and in the range of pH $9.0{\sim}11.0$, neutral thioglycolic acid molecule and thioglycolic acid anion competitively attacted the double bond. By contrast, above pH 11.0, the reaction was dependent upon only the addition of thioglycolic acid anion.

• 대한화학회지
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• 제32권3호
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• pp.260-266
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• 1988

${\beta},\;{\beta}$-Dichlorostyrene 유도체(p-H, p-Cl, $p-CH_3,\;및\;p-OCH_3$)에 대한 thioglycolic acid 및 cysteine의 친핵성 첨가반응속도를 자외선 분광분석법으로 측정하여 pH에 따르는 반응속도상수의 변화, 일반염기(general base) 및 치환기 효과등으로 부터 넓은 pH범위에서 실험치와 잘 일치하는 반응속도식을 구하였고, 실험사실에 잘 맞는 반응 메카니즘을 제안하였다. 즉 pH 9.0 이상에서의 반응속도는 sulfide anion이 pH $9.0{\sim}7.0$에서는 thioglycolic acid 및 cysteine의 중성분자와 그의 anion들이 경쟁적으로 첨가되며 pH 7.0 이하에서는 thioglycolic acid 및 cysteine의 중성분자만이 첨가됨을 알았다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 1986년도 추계학술대회
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• pp.525.2-525
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• 1986

Cephalexin synthesizing enzyme (${\alpha}$ amino acid ester hydrolase) was partially purified from the culture broth of Acetobacter turbidans ATCC9325 through ammonium sulfate fractionation, DEAE, CM, and Sephacryl S-200 gel filtration. The enzyme has optimum pH 6.0 and temperature, 40$^{\circ}C$ respectively. From the analysis of reaction mixtures by thin layer chromatographic and high performance liquid chromatographic techniques, it was confirmed this enzyme catalyzed simultaneously the following reactions : 1) Synthesis of cephalexin from D-${\alpha}$-phenylglycine methylester (PGM) and 7-amino 3-deacetoxy-cetoxycephalosporanic acid (7-ADCA) 2) Hydrolysis of cephalexin to form 7-ADCA and phenylglycine (PG) 3) Hydrolysis of PGM to form PG and methanol. Base on the above experimental observations, the reaction model of this enzyme was identical with that of the enzyme from Xanthomonas citri.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제31회 춘계학술대회
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• pp.99-105
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• 2000

Greases composed of base oil and thickener are widely used in the purpose of lubrication and anti-corrosion of machinery. However, greases are sometimes oxidized and decomposed by heat of friction, and produced organic acid. And the greases leaked out ordinary spot make the concrete structures weaken. In this study, the chemical effects of the greases with the concrete structures were investigated through oxidation reaction under pressure and oxygen, and evaluated by the analysis of TAN, Ca content, FT-IR and XRD of grease and cement powder after the oxidation reaction. As the results, TAN value decreased with the increase of the content of cement because of neutralization of organic acid produced by the oxidation of grease with calcium contained in the cement. The content of calcium linearly increased with the increase of cement due to calcium salt by neutralization of acid. Also, according to XRD results of the cement powder oxidized at 99 $^{\circ}C$, the diffraction peak due to calcium hydroxide decreased in comparison with that at room temperature because of the reaction of calcium and organic acid.

• 약학회지
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• 제34권6호
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• pp.415-421
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• 1990

The effects of temperature, pH, light and concentration on the degradation of trimebutine maleate in aqueous solution were investigated on the basis of accelerated stability analysis, and the stabilization of the solution was attempted by addition of several additives. The decomposition of trimebutine maleate in solution followed first-order reaction the was not only accelerated by temperature elevation but also the lower the concentratin the more speeded up the reaction. The decomposition mechanism of trimebtine could be confirmed by hydrolysis of ester bond in the structure. It was assumed trimebutine maleate is so photosensitive that the solution of the drug underwent accelerated decomposition under UV rays. What is more, the degradation of trimebutine solution was supposed to catalyzed by specific acid-base catalysis considered the pH dependence for the hydrolysis of ester, and the solution was most stable over the range of pH 2-2.8 in solution. The additives, citric acid, asparitc acid and glutamic acid, inhibited considerably the decomposition of the drug solution, and these additives might be used as stabilizers in trimebutine maleate solution.