• 한국세라믹학회지
• /
• 제28권3호
• /
• pp.205-214
• /
• 1991

Calcium carbonate fine powders were synthesized by blowing CO2 gas in CaO or Ca(OH)2 suspension, and the shapes of powders obtained were examined for each synthetic condition. When water was used as a solvent, ultrafine calcite powders with the average size of∼0.03$\mu\textrm{m}$ were obtained. When synthesized using methanol as a solvent, amorphous phase and spherical vaterite phase were obtained by suction filtering and non-filtering, respectively. Reaction did not occured in ethanol medium, but spherical vaterite phase was obtained by adding ethylene glycol in ethanol.

• Bulletin of the Korean Chemical Society
• /
• 제26권11호
• /
• pp.1771-1775
• /
• 2005

An efficient and environment friendly method has been described for the synthesis of various 2-alkyl-4-hydroxy-2H-1,2-benzothiazine-3-carboxamide-1,1-dioxides starting from N-alkylation of sodium obenzosulfimide in an ionic liquid for the first time. Ring cleavage and ring closure of the resulting product were achieved in a single step in a cost effective solvent (methanol) followed by N-alkylation of resulting alkyl 4-hydroxy-2H-1,2-benzothiazine-3-carboxylate in ionic liquid while boron triflouride was used as a catalyst along with molecular sieves in carboxamide formation step.

• Journal of Microbiology and Biotechnology
• /
• 제22권9호
• /
• pp.1202-1207
• /
• 2012

A gene, ClCDA, encoding chitin deacetylase from Colletotrichum lindemuthianum, was optimized according to the codon usage bias of Pichia pastoris and synthesized in vitro by overlap extension PCR. It was secretorily expressed in P. pastoris GS115 using the constitutive expression vector pHMB905A. The expression level reached the highest with 110 mg/l culture supernatant after 72 h of methanol induction, which comprised 77.27 U/mg chitin deacetylase activity. SDS-PAGE, mass spectrometry, and deglycosylation assays demonstrated that partial recombinant protein was glycosylated with an apparent molecular mass of 33 kDa. The amino acid sequences of recombinant proteins were confirmed by mass spectrometry.

• 한국미생물·생명공학회지
• /
• 제24권2호
• /
• pp.222-226
• /
• 1996

The enzymatic synthesis of 3, 4-dihydroxyphenyl-L-alanine (L-DOPA) was examined for the effects of the reaction additives such as sodium borate, alcohol, and organic solvents. The enzyme used was tyrosine phenol-lyase of Citrobacter freundii KCTC 2006 produced in Escherichia coli. The amounts of tyrosine phenol-lyase and pyridoxal-5-phosphate were optimized to 2.0 units/ml and 0.1 mM, respectively, for the synthetic reaction. Sodium borate, a substance that forms a complex with pyrocatechol, reduced the enzyme deactivation by pyrocatechol although it seriously inhibited the enzyme activity. Among the organic solvents tested, dimethylsulfoxide, dimethylformamide, and alcohol increased the productivity of the L-DOPA synthesis. In a reaction system with 5% methanol, L-DOPA concentration increased up to 210 mM after 24 hours, and 77.1% of which was separated as precipitates. The L-DOPA was purified to 99.96% by solubilizing and recrystallyzing the precipitates.

• 대한안전경영과학회지
• /
• 제1권1호
• /
• pp.259-272
• /
• 1999

In order to enhance the selectivity, productivity and yield of methyl fructoside, which was synthesized by enzymatic glycosylation of sucrose and methanol solution, controlling of surface property of solid support using different immobilization procedures optimized microenvironment of immobilized invertase. Silanization and polyethylene imine coating methods were adopted to give a hydrophobic and hydrophilic environment of immobilized invertase. As a result, polyethyleneimine coating method gave higher loading of enzyme, effective activity, and relative activity than silanization method, because it brought on increasing the functional density of amino group and enhancing the conservation of activity by regulating of hydrophilicity. And then, hydrophilic environment was possible to restraint the assessing of methyl fructoside molecule, which was more hydrophobic than sucrose, fructose, and glucose molecule in the reaction mixture, into .the active site of immobilizedinvertase. Consequently, hydrophilic microenvironment of immobilized invertase by polyethyleneimine coating obtained higher yield and productivity with increasing conversion than silanized and native invertase. Thus, this procedure optimized the microenvironment of immobilized invertase suitable for the enzymatic synthesis of methyl fructoside.

• Bulletin of the Korean Chemical Society
• /
• 제28권5호
• /
• pp.751-757
• /
• 2007

To develop new COX-2 inhibitors, 1,5-diarylhydantoins and 1,5-diaryl-2-thiohydantoins were synthesized from phenylacetic acids by esterification, bromination, C-N bond formation and cyclization. Esters 1-3 were efficiently synthesized from the starting materials by reflux in absolute methanol for 3 h containing concentrated sulfuric acid as catalyst. Bromination was carried out with N-bromosuccinimide at rt in dichloromethane. Bromides 4-6 were reacted with aniline, p-anisidine, sulfanilamide in ethanol (or N,N-dimethylformamide) to provide the amines 7-15. Hydantoins and 2-thiohydantoins 16-46 were synthesized from amines 7-15 by treating them with potassium isocyanate (or potassium thiocyanate) and triethylamine. The synthetic process from alkyl α-anilinophenylacetate 7-15 to 3-alkylhydantoins was carried out in a one-pot reaction using alkyl isocyanate (alkyl isothiocyanate).

• 약학회지
• /
• 제35권5호
• /
• pp.368-371
• /
• 1991

For the development of new antiulcer agents 5, 6-dihydroimidazo[2, 1-b]- thiazoles substituted at the 3-position are sythesized. Thus, the reaction of 3-chloromethyl-5, 6-dihydroimidazo[2, 1-b]thiazole(2) with thiourea and subsequently with 3-chloro-propionitrile gives 3-[3-[5, 6-dihydroimidazo[2, 1-b]thiazolyl]methylthio]propionitrile(4), which by partial alcoholysis with methanol is converted into methyl-3-[3-[5, 6-dihydro-imidazo[2, 1-b]thiazoyl]methylthio]propionimidate(5) . This compound(5) is treated finally with sulfamide or sulfonamides. 3-[3-[5, 6-dihydroimidazo[2, 1-b]thiazoyl]methylthiol-N$^{2}$-sulfamoyl-propionamidine(6) inhibited gastric acid secretion (45%) when administered intraduodenally (100 mg/kg) to pylorus-ligated rats.

• Korean Chemical Engineering Research
• /
• 제49권1호
• /
• pp.21-27
• /
• 2011

메탄올 수증기 개질반응에 대한 적용가능성을 파악하기 위하여 메탄올 합성용 촉매인 ICI-M45와 수성가스 전환반응용 촉매인 MDC-3와 MDC-7을 비교 연구하였다. 또한 수성가스전환 반응에 대한 세 촉매의 비교실험도 수행하였다. 그 결과 MDC-7이 메탄올 수증기 개질반응에서 가장 높은 전화율을 보였으며, $H_2$와 $CO_2$ 생성속도 또한 높게 나타났다. 수성가스 전환반응용 촉매인 MDC-7과 메탄올 합성촉매인 ICI-M45를 이용하여 촉매 충진 방법에 따른 메탄올의 전화율에서의 변화를 살펴본 결과, MDC-7 단독보다 낮은 메탄올의 전화율을 보였다. 수성가스 전환반응에서도 DC- 7, MDC-3, 그리고 ICI-M45의 순으로 반응성이 감소하였다. 상기 두 반응에서 MDC-7이 가장 우수한 이유로는 높은 비표면적과 Cu의 분산도, 그리고 적절한 Cu와 Zn의 비율에 기인함을 확인할 수 있었다.

• 한국재료학회지
• /
• 제33권7호
• /
• pp.265-272
• /
• 2023

In this study, the synthesis of nitrobenzene was carried out using sulfated silica catalyst. The study delved into H₂SO₄/SiO₂ as a solid acid catalyst and the effect of its weight variation, as well as the use of a microwave batch reactor in the synthesis of nitrobenzene. SiO₂ was prepared using the sol-gel method from TEOS precursor. The formed gel was then refluxed with methanol and calcined at a temperature of 600 ℃. SiO₂ with a 200-mesh size was impregnated with 98 % H₂SO₄ by mixing for 1 h. The resulting 33 % (w/w) H₂SO₄/SiO₂ catalyst was separated by centrifugation, dried, and calcined at 600 ℃. The catalyst was then used as a solid acid catalyst in the synthesis of nitrobenzene. The weights of catalyst used were 0.5; 1; and 1.5 grams. The synthesis of nitrobenzene was carried out with a 1:3 ratio of benzene to nitric acid in a microwave batch reactor at 60 ℃ for 5 h. The resulting nitrobenzene liquid was analyzed using GC-MS to determine the selectivity of the catalyst. Likewise, the use of a microwave batch reactor was found to be appropriate and successful for the synthesis of nitrobenzene. The thermal energy produced by the microwave batch reactor was efficient enough to be used for the nitration reaction. Reactivity and selectivity tests demonstrated that 1 g of H₂SO₄/SiO₂ could generate an average benzene conversion of 40.33 %.

• Bulletin of the Korean Chemical Society
• /
• 제32권6호
• /
• pp.1957-1964
• /
• 2011

Various reaction conditions uding temperature, time and type and concentration of templates have been changed in order to facilely synthesize, especially with microwave (MW) heating, SAPO-34 molecular sieves. SAPO-34 molecular sieve can be synthesized rapidly with microwave irradiation from a gel containing tetraethylammonium hydroxide (TEAOH) as a template. However, other several templating molecules lead to SAPO-5 molecular sieve under microwave irradiation even though SAPO-34 is obtained by conventional electric synthesis from the same reactant gels. Moreover, SAPO-34 can be obtained more easily by increasing the TEAOH or silica concentration or by increasing the reaction temperature. SAPO-34 can be obtained within 5 min in a selected condition (high temperature of 210 $^{\circ}C$) with microwave heating, which may lead to a continuous production of the important material. SAPO-34 synthesized by microwave irradiation is homogeneous and small in size and shows acidity and a stable performance in the dehydration of methanol and 2-butanol to olefins, suggesting potential applications in acid catalysis.