A New Approach to Inducing Silicon Tethered Ring-closing Metathesis Reactions

IntroductionGrubbs catalyst bis(tricyclohexylphosphine)benzylidene ruthenium( ) dichloride1 can be usedin a variety of ring- closing metathesis (RCM )reactions,cross metathesis(CM) reactions andring- opening metathesis polymerization(ROMP) [1— 4 ] .It remains metathetically active inthe presence of a variety of functional groups,suchas carbonyls,alcohols,and amides[1] .The use ofcatalyst1 in the synthesis has drawn more andmore attention[5— 13] . However,this catalyst is veryexpensive,an…     

Purification of Single-walled Carbon Nanotubes Grown by a Chemical Vapour Deposition (CVD) Method

ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｇｌｅ ｗａｌｌｅｄｃａｒｂｏｎｎａｎｏｔｕｂｅｓ(ＳＷＮＴｓ)ｈａｖｅｂｅｅｎｓｙｎｔｈｅｓｉｓｅｄｂｙｕｓｉｎｇｖａｒｉｏｕｓｍｅｔｈｏｄｓ[1— 3] ａｎｄｔｈｅｃｈｅｍｉｃａｌｖａｐｏｕｒｄｅｐｏｓｉｔｉｏｎ (ＣＶＤ )ｍｅｔｈｏｄｈａｓｂｅｅｎｃｏｎｓｉｄｅｒｅｄａｓａ ｐｒｏｍｉｓｉｎｇｍｅｔｈｏｄｔｏ ｐｒｏｄｕｃｅＳＷＮＴｓｏｎａｎｉｎｄｕｓｔｒｉａｌｓｃａｌｅ[3— 5] .Ｈｏｗｅｖｅｒ ,ａｌｌｔｈｅＳＷＮＴ ｐｒｏｄｕｃｔｓｓｙｎｔｈｅｓｉｓｅｄｔｏｄａｔｅｃｏ…     

Cosolvent Effect on the Tautomerism of Ethyl Acetoacetate in Supercritical CO_2

There are some unique advantages for chemical reactions in SCFs. For example, reaction rates, yields, and selectivity can be tuned by pressure or small amount of cosolvent. SCFs can be used to replace environmentally undesirable solvents. It is not surprised that in recent years the use of SCFs as solvents for chemical reaction media has received much attention. However, mechanism for the effect of pressure and cosolvents on chemical reactions is not very clear. Tautomeric reactions are id…     

Synthesis and Structure of E-2-(2,4,6-tri tert butylphenylphosphinyl)-2-〔N-(tert-butyldimethylsilyl)-N-(p-chrolophenyl)〕amino-1-(2,4,6-tri tert-butyl-phenyl)phosphacthylene

1　INTRODUCTIONItwaswellknown thatelementsofthesecondary and higherrow are in generaldifficulty to form multiplebondsin which apπ hybridized stateisinvolved〔1〕.Thus,simple compounds containing multiple phosphorus carbon bonds,such as methyl dynephosphine( HC≡P) 〔2 - 3〕 and methylenephosphine( H2 C=PH〔4〕,are notstableat room temperature.Three methods to stabilize compounds containing double ormultiple bond involving phosphorusatom in the pπ hybridized state are often used.The f…     

Mono-Allylation of Gem-Diacetates with Allylsamarium Bromide

Our group have explored the reaction of allylsamarium bromide with a variety of substrates, such as N-(2-aminoalkyl)benzotriazoles1, imines2, nitriles3, diorgano diselenides4, disulfides5, isocyanates6 and nitroalkenes7. Here we wish to report the monoallylation of gem-diacetates with allylsamarium bromide. Gem-diacetates are stable in neutral and basic media, thus they are frequently used to protect aldehydes8. However, the presence of two leaving groups at the same carbon may make carbon …     

Site-specifically Hydrolytic Cleavage of Oxidized Insulin B Chain With Cu(II) Ion

Selectively chemical cleavage of peptides and proteins is one of the most important reactions in both chemical and biochemical processes. Over the past decade, the interaction of palladium(II) complexes with methionine, cysteine and histidine-containing peptides and proteins and the hydrolytic cleavage of the corresponding amide bond by Pd(II) complexes have been extensively studied1-13. However, reports concerning the directly selective hydrolysis of peptides and proteins with other simple …     

Prototype studies on the forward MWDC tracking array of the external target experiment at HIRFL-CSR

A prototype of the forward tracking array consisting of three multiwire drift chambers (MWDC) for the external target experiment (CEE) at the Heavy Ion Research Facility at the Lanzhou -Cooling Storage Ring (HIRFL-CSR) has been assembled and tested using cosmic rays. The signals from the anode wires are amplified and fed to a Flash-ADC to deliver the drift time and charge integration. The performances of the array prototype are investigated under various high voltages. For the tracking performances, after the space-time relation (STR) calibration and the detector displacement correction, the standard deviation of 223 μm of the residue is obtained. The performances of the forward MWDCs tracking array meets the requirements of CEE in design.     

H-Bonding Self-assembled Template-directed Synthesis of a Reactive Amide-bridged Ladder Polyvinylsiloxane

Ladder polysiloxanes (LPS) including both oxygen-bridged ladder polysilsesquioxanes (LPSQ) and organo-bridged ladder polysiloxanes (OLPS) are very important materials because of their excellent properties1. Adrianov et al. in 1960 attempted to prepare 1, …     

Novel preparation of NaA/carbon nanocomposite thin films with high permeance for CO2/CH4 separation

Novel NaA/carbon nanocomposite thin films were successfully prepared on a porous a-Al2O3 substrate by incorporatingnanosized NaA zeolite into novolak-type phenolic resin.The prepared films were characterized by XRD,SEM and single gaspermeation tests.The NaA zeolite/carbon nanocomposite thin films exhibited that the ideal separation factor of CO2/CH4 was 28.4and the carbon dioxide flux was 3.39*10-7mol/(Pa m2s)at room temperature and under a pressure difference of 100 kPa,whichwas two orders of magnitude higher than that of pure carbon membrane prepared at the same procedures and conditions as those ofcomposite films.From the SEM images,the films were continuous and highly intergrown.Compared with carbon membranes,thethickness of nanocomposite films was drastically decreased,which was helpful to reduce the diffusion resistance and increase theflux of gas permeance.     

Capillary electrophoresis with direct chemiluminescence detection for the analysis of catecholamines in human urine

A rapid and sensitive method for the analysis of three catecholamines by capillary electrophoresis(CE)with directchemiluminescence(CL)detection is described.The detection limits(S/N=3)were 1.3*10-8g/mL for isoprenaline,1.0*10-8g/mL for epinephrine and 2.8*10-8g/mL for dopamine.The proposed method was successfully applied to theanalysis of catecholamines in urine samples of cigarette smokers and nonsmokers.The results showed that there is a close relationbetween the release of dopamine in human body fluids and cigarette smoking/nonsmoking.