摘要:
Disclosed is a continuous process for the production of optically pure (S)-β-hydroxy-γ-butyrolactone having constantly maintained optical activity, consisting of hydrogenating 2-50 wt % of a substituted carboxylic acid derivative in a solvent using a fixed bed reactor filled with a precious metal catalyst-impregnated inorganic oxide carrier at 50-500° C. under pressure of 15-5,500 psig at weight-space-velocity of 0.1-10 h−1, in which a molar ratio of hydrogen to carboxylic acid derivative ranges from 2 to 10. The desired material can be produced in higher optical purity and at higher yield by the current process which is relatively simpler and environmentally safer than conventional processes. Additionally, increased production efficiency leads to production of the desired material on a large scale.
摘要:
A hinge apparatus includes a substantially cylindrical holder having at least one guide hole with a predetermined degree slope that extends in a longitudinal direction. A hinge shaft includes a substantially cylindrical surface configured to linearly move in the longitudinal direction of the holder. A guide pin has an end located inside the guide hole and is configured to extend through the cylindrical surface of the hinge shaft. Therefore, when the hinge shaft moves linearly in the holder, the guide pin moves along the guide hole so that the hinge shaft rotates in the holder.
摘要:
Disclosed is a method for selective dealkylation of alkyl-substituted C9+ aromatic compounds using a bimodal porous dealkylation catalyst at a low temperature. The catalyst has a bimodal porous structure including both mesopores and micropores. The catalyst includes a crystalline aluminosilicate and a metal. The catalyst is highly active at a low temperature. According to the method, C9+ aromatic compounds substituted with at least one C2+ alkyl group as by-products formed by xylene production can be selectively dealkylated and converted to BTX, etc. on a large scale within a short time. In addition, the method is an environmentally friendly process entailing reduced waste treatment cost when compared to conventional mesitylene production methods. Therefore, high value-added mesitylene can be separated from low value-added C9+ aromatic compounds at lower cost compared to conventional methods. Furthermore, the supported metal catalyst is easy to recover after dealkylation and is recyclable, thereby contributing to reduced cost.
摘要:
Disclosed is a method for selective dealkylation of alkyl-substituted C9+ aromatic compounds using a bimodal porous dealkylation catalyst at a low temperature. The catalyst has a bimodal porous structure including both mesopores and micropores. The catalyst includes a crystalline aluminosilicate and a metal. The catalyst is highly active at a low temperature. According to the method, C9+ aromatic compounds substituted with at least one C2+ alkyl group as by-products formed by xylene production can be selectively dealkylated and converted to BTX, etc. on a large scale within a short time. In addition, the method is an environmentally friendly process entailing reduced waste treatment cost when compared to conventional mesitylene production methods. Therefore, high value-added mesitylene can be separated from low value-added C9+ aromatic compounds at lower cost compared to conventional methods. Furthermore, the supported metal catalyst is easy to recover after dealkylation and is recyclable, thereby contributing to reduced cost.
摘要:
Disclosed are a nitride semiconductor light emitting device and a method for manufacturing the same. The nitride semiconductor light emitting device includes a first nitride layer, an active layer including at least one delta-doping layer on the first nitride layer through delta-doping, and a second nitride layer on the active layer.
摘要:
A portable terminal includes a main body, cradle mounted to the main body, and a covering with one portion fixed on the cradle, the covering surrounding at least one surface of the main body. Accordingly, the appearance of the portable terminal may be diversified by providing the covering using the cradle that can be mounted to the main body of the portable terminal. Thus, various textures and colors can be provided according to the structure of the covering, and the covering can be separated from the cradle, thereby contributing to the diversification of the design of the portable terminal.
摘要:
A pulse control device is maintained with a constant pulse width corresponding to a change of process or temperature. The pulse control device comprises a fuse set for selectively outputting a delay increase signal and a delay decrease signal that have a different state based on a cutting or non-cutting state of a fuse on which information on a change of process is programmed, and a pulse generator provided with a plurality of delay cells with predetermined time delay for selectively increasing or decreasing the number of the plurality of delay cells depending on the delay increase signal and the delay decrease signal to generate an internal clock with a pulse width corresponding to the number of the increased or decreased delay cells.
摘要:
Provided are a delay locked loop (DLL) and a method for generating a divided clock therein. In the DLL, a width of a reference frequency for phase comparison can be changed depending on a magnitude of an operating frequency. In the DLL, a clock buffer receives a clock equal to an external clock and generates an internal clock. An enable clock generator generates a 1-period enable clock or a 2-period enable clock using a command signal generated for performing a predefined operation. The command signal is generated according to an address command signal inputted from an exterior. A clock divider divides the internal clock to generate a divided clock. The divided clock is controlled by the 1-period enable clock or the 2-period enable clock, such that the divided clock is made to be a 1-period based dividing clock or a 2-period based dividing clock.
摘要:
The present invention relates to a continuous process for the preparation of [3S-(3&agr;, 4a&bgr;, 8a&bgr;)]-N-tert-butyl-decahydro-3-isoquinolinecarboxamide, an intermediate useful in the synthesis of compounds for the treatment of viral diseases, from the reduction of N-tert-butyl-1,2,3,4-tetrahydro-3(S)-isoquinolinecarboxamide with a noble metal catalyst supported on inorganic oxide carrier in a fixed bed reaction system, with a high optical yield.
摘要:
Disclosed is a process for the production of optically pure (S)-beta-hydroxy-gamma-butyrolactone through the hydrogenation of substituted carboxylic acid derivatives. A solution containing 1 to 50% by weight of a substituted carboxylic acid derivative is fed at a WHSV of 0.1 to 10 h−1, to a fixed bed reactor which is filled with a catalyst and maintained at a reaction temperature of 50 to 550° C. under a halogen partial pressure of 15 to 5,500 psig. The catalyst is composed of a noble metal as a catalytically effective ingredient which is impregnated in an inorganic oxide as a support. The molar ratio of the hydrogen to the substituted carboxylic acid derivative is maintained at a molar ratio of 1:1 to 10:1. The process can produce optically pure (S)-beta-hydroxy-gamma-butyrolactone with higher purities at higher yields than can conventional techniques. In addition to being relatively simple and environmentally friendly, the process is so economically favorable as to apply to industrial production.