• Bulletin of the Korean Chemical Society
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• v.15 no.2
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• pp.132-138
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• 1994

Bis(diethylamino)aluminum hydride was utilized in a systematic study of the approximate rates and stoichiometry of the reaction of excess reagent with 55 selected organic compounds containing representative functional groups under standardized conditions (THF, $0^{\circ}C$, reagent to compound=4 : 1) in order to define the characteristics of the reagent for selective reductions. The reducing action of BEAH was also compared with that of the parent aluminum hydride. The reducing action of the reagent is quite similar to that of aluminum hydride, but the reducing power is much weaker. Aldehydes and ketones were readily reduced in 1-3 h to the corresponding alcohols. However, unexpectedly, a ready involvement of the double bond in cinnamaldehyde was realized to afford hydrocinnamyl alcohol. The introduction of diethylamino group to the parent aluminum hydride appears not to be appreciably influential in stereoselectivity on the reduction of cyclic ketones. Both p-benzoquinone and anthraquinone utilized 2 equiv of hydride readily without evolution of hydrogen, proceeded cleanly to the 1,4-reduction products. Carboxylic acids and acid chlorides underwent reduction to alcohols slowly, whereas cyclic anhydrides utilized only 2 equiv of hydride slowly to the corresponding hydroxylacids. Especially, benzoic acid with a limiting amount of hydride was reduced to benzaldehyde in a yield of 80%. Esters and lactones were also readily reduced to alcohols. Epoxides examined all reacted slowly to give the ring-opened products. Primary and tertiary amides utilized 1 equiv of hydride fast and further hydride utilization was quite slow. The examination for possibility of achieving a partial reduction to aldehydes was also performed. Among them, benzamide and N,N-dimethylbenzamide gave ca, 90% yields of benzaldehyde. Both the nitriles examined were also slowly reduced to the amines. Unexpectedly, both aliphatic and aromatic nitro compounds proved to be relatively reactive to the reagent. On the other hand, azo- and azoxybenzenes were quite inert to BEAH. Cyclohexanone oxime liberated 1 equiv of hydrogen and utilized 1 equiv of hydride for reduction, corresponding to N-hydroxycyclohexylamine. Pyridine ring compounds were also slowly attacked. Disulfides were readily reduced with hydrogen evolution to the thiols, and dimethyl sulfoxide and diphenyl sulfone were also rapidly reduced to the sulfides.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.4
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• pp.247-253
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• 2012

The objective of this study was to find the frequency that most effectively generates hydroxyl radical and to investigate the effect of solution volume on the oxidation of arsenite (As[III]) under the determined frequency. Based on the cavitation yield for hydrogen peroxide, hydroxyl radical is formed most effectively under the frequency of 300 kHz. The experiment was performed with various solution volumes (334, 690, 1,046, and 1,401 mL) under 300 kHz. Results showed that as solution volume increased, kinetic constant for arsenite oxidation decreased. However, cavitation yield for arsenite decreased in small volumes (334, and 690 mL) but maintained or increased in large volumes (1,046, and 1,401 mL) over a set period of time (10, 30, and 60 min). Based on the kinetic constant result, it is more advantageous to oxidize arsenite in small volumes. However, according to the cavitation yield for arsenite, it is applicable to oxidize arsenite in large volumes over a long period of time.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.443-450
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• 2014

Selective catalytic reduction of nitrogen monoxide by hydrogen ($H_2$-SCR of NO) over platinum catalysts impregnated on zirconia-incorporated silica ($ZrO_2-SiO_2$) and manganese oxide ($MnO_x$) was investigated. $Pt-MnO_x$ catalyst showed low conversions and low yields of $N_2O$ and $NO_2$ at $100{\sim}350^{\circ}C$. On the other hand, NO conversions over $Pt/ZrO_2-SiO_2$ were very high, but $N_2O$ was predominantly produced at $100-150^{\circ}C$ and the yield of $NO_2$ increased with temperature at $200-300^{\circ}C$, resulting in poor $N_2$ yields. $Pt-MnO_x/ZrO_2-SiO_2$ exhibited a small enhancement in $N_2$ yield at $100-150^{\circ}C$ due to the synergy of $MnO_x$ and $ZrO_2-SiO_2$. The surface composition and oxidation state of the catalyst components and the acidity of the catalysts were examined. IR spectra of the adsorption of NO and their subsequent reactions with hydrogen on these catalysts were also recorded. The variations of conversion and product yield according to the catalyst components in the $H_2$-SCR of NO were discussed in relation to their catalytic roles.

• Journal of Microbiology and Biotechnology
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• v.26 no.1
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• pp.80-88
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• 2016

The enzyme-catalyzed Henry reaction was realized using deep eutectic solvents (DESs) as a reaction medium. The lipase from Aspergillus niger (lipase AS) showed excellent catalytic activity toward the substrates aromatic aldehydes and nitromethane in choline chloride:glycerol at a molar ratio of 1:2. Addition of 30 vol% water to DES further improved the lipase activity and inhibited DES-catalyzed transformation. A final yield of 92.2% for the lipase AS-catalyzed Henry reaction was achieved under optimized reaction conditions in only 4 h. In addition, the lipase AS activity was improved by approximately 3-fold in a DES-water mixture compared with that in pure water, which produced a final yield of only 33.4%. Structural studies with fluorescence spectroscopy showed that the established strong hydrogen bonds between DES and water may be the main driving force that affects the spatial conformation of the enzyme, leading to a change in lipase activity. The methodology was also extended to the aza-Henry reaction, which easily occurred in contrast to that in pure water. The enantioselectivity of both Henry and aza-Henry reactions was not found. However, the results are still remarkable, as we report the first use of DES as a reaction medium in a lipase-catalyzed Henry reaction.

• Textile Coloration and Finishing
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• v.23 no.3
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• pp.155-162
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• 2011

para-Aramid has limited dyeability because of its highly crystalline structure and compactness. To improve the dyeability of the para-aramid to reactive dyes of bright color in deep shade, the fabrics were photografted under continuous UV irradiation with dimethylaminopropyl methacrylamide and 4-benzoyl benzoic acid as a monomer and a hydrogen -abstractable photoinitiator respectively. A UV energy of 35J/$cm^2$ and a photoinitiator concentration of ten percent or more with respect to the monomer in the formulation was required for optimal photografting. Grafting yield increased with higher monomer application level. Surface analysis indicated significant alterations in the atomic composition of the photografted fabric surface and the fabric surface was covered with the grafted polymers. While the pristine para-aramid fabrics showed no appreciable dyeability to the ${\alpha}$-bromoacrylamide reactive dyes, the grafted para-aramid fabrics enhanced the dyeability to the reactive dyes substantially. In case of C.I. Reactive Blue 50, a K/S value of 8.7 can be obtained with the grafted para-aramid fabrics with a grafting yield of 2.3 %. Also the color fastness properties of the dyed fabrics was excellent in the conditions of washing, rubbing and light irradiation.

• Microbiology and Biotechnology Letters
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• v.17 no.5
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• pp.421-428
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• 1989

A soil bacterium synthesizing an extremely viscous biopolymer was isolated and identified as Pseudomonas delafieldii. The optimal pH and temperature for the growth were 6.5 and 3$0^{\circ}C$, respectively. Maximum specific growth rate was 0.24 h$^{-1}$. The specific polysaccharide productivity, growth yield and product yield were 6.25 mg/g-cell/h, 54.5% and 38.39%, respectively. The polysaccharide was presumed to be $\beta$-glucan containing glucose and gluconolactone (1.9：1.0 in molar ratio) and 1.35 % acetyl group, Element analysis showed that it contained carbon (31.85%) and hydrogen (5.15%). The weight average molecular weight by GPC was 5.64$\times$10$^7$. The intrinsic viscosity was 42.84 dl/g.

• Bulletin of the Korean Chemical Society
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• v.35 no.11
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• pp.3205-3208
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• 2014

Catalytic gasification of cellulose was carried out in a U-type fixed reactor with Ni loaded MSU-F catalyst (Ni/MSU-F) and Ni loaded ${\gamma}-Al_2O_3$ (Ni/${\gamma}-Al_2O_3$). The characteristics of the catalysts were analyzed by using X-ray diffraction, $H_2$-temperature programmed reduction, and Brunauer-Emmett-Teller analyses. The operation conditions of catalytic gasification reactions were $750^{\circ}$ and 0.2 equivalence ratio. Air was used as gasification agent. Catalytic gasification characteristics, such as gas yield and gas composition ($H_2$, CO, $CO_2$, $C_1-C_4$), were measured and calculated. The gas yield of Ni/MSU-F was much higher than that of Ni/${\gamma}-Al_2O_3$. Especially high amount of hydrogen was produced by Ni/MSU-F.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.5 no.1
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• pp.34-37
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• 2004

Effect of $H_2$ spillover rate as functon of calcination temperature on reaction kinetics was evaluated. Reaction kinetics including yield, conversion and selectivity of 1-butene isomerization over $Pt/HxMoO_3/SiO_2$ were measured as reaction temperature was increased. While conversion of 1-butane was decreased, yield of iso-butene was increased. Two kinds of reaction mechanism were proposed from the change of selectivity as function of temperature.

• Journal of Pharmacopuncture
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• v.15 no.2
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• pp.24-30
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• 2012

This study compared Ojeok-san (Wuji-san in Chinese) decoctions produced using different extraction methods for variable times. Decoctions were extracted in pressurized or non-pressurized conditions for 60, 120, and 180 mins. We investigated the Ojeok-san extract yield, the total soluble solid content, the hydrogen ion concentration (pH), and the reference compound content. The extract yield and the total soluble solid content were higher in decoctions produced by non-pressurized extraction; both were proportional to the extraction time. The pH tended to decrease as the extraction time was increased in decoctions produced using both methods. After 60 and 180 mins, the levels of albiflorin, paeoniflorin, nodakenin, naringin, and neohesperidin were significantly higher in decoctions extracted using the non-pressurized method compared with those extracted using the pressurized method. After 120 mins, only cinnamaldehyde was extracted in a greater amount in pressurized decoctions compared with non-pressurized decoctions. The levels of paeoniflorin, ferulic acid, nodakenin, naringin, hesperidin, neohesperidin, and glycyrrhizin increased with time in non-pressurized decoctions. This study showed that the use of pressurized and non-pressurized extraction methods for different times affected the composition of Ojeoksan (Wuji-san) decoctions.

• Journal of the Korean institute of surface engineering
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• v.47 no.6
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• pp.354-361
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• 2014

In order to utilize silicon carbide (SiC) as an inner part of fluidized bed reactor (FBR) for manufacturing poly-silicon, we have carried out the thermodynamic calculation on the overall reactions including poly-silicon synthesis and compatibility of SiC with FBR process. The resources of silicon included $SiH_4(MS)$, $SiHCl_3(TCS)$ and $SiCl_4(STC)$ and the thermodynamic yield of the FBR with MS, TCS and STC were compared each other with variable range of temperature, pressure and hydrogen to silicon ratio. The silicon yield of MS, TCS and STC were 100%, 28% and 4%, respectively, throughout the conventional FBR conditions. Silicon carbide having high hardness and strength showed strong resistance to granule collisions during the FBR process using a lab-scale reactor. And it also showed quite good compatibility with the typical FBR processes of MS and TCS resources.