GC-MS STUDY ON DIURETICS IN URINE Ⅱ.DETECTION METHOD USING TRIMETHYLSILYLATION

A reliable method is described for the detection of amitoride,triamterene. canrenone and spironolactone in human urine using GC-MS analysis after trimethytsitytation.The mass spectrometric and metabotic features of the compounds are discussed

Nanocrystalline TiO_2 as an efficient and reusable catalyst for the chemoselective trimethylsilylation of primary and secondary alcohols and phenols

Nanocrystalline TiO_2 was used as an efficient and recyclable catalyst for the chemoselective trimethylsilylation of primary and less hindered secondary alcohols and phenols with hexamethyldisilazane（HMDS）.All reactions were performed under mild and completely heterogeneous conditions in good to excellent yields.

Determination of free fatty acids in rabbit plasma by GC-MS after trimethylsilylation derivatization

In the present study, free fatty acids(FFAs, including palmitic acid, stearic acid, oleic acid, linoleic acid and arachidonic acid) in rabbit plasma were determined by gas chromatography-mass spectrometry(GC-MS) after trimethylsilylation derivatization using N,O-bis(trimethylsilyl)trifluoroacetamide(BSTFA) – trimethylchlorosilane(TMCS) as derivatization reagent. The experimental conditions, including extraction and silylation reaction, were investigated. The method was experimentally validated. The linearity between fatty acids’ peak areas and their concentrations was obtained with the corelative coefficient(r2) all more than 0.999, and the recoveries were between 82% and 111%. The intra-day variations of FFAs’ in plasma samples at different concentrations were all less than 6%. FFA analysis results of 16 rabbit plasma samples showed that the method could be well applied in the determination of plasma samples in vivo. In contrast to the traditional method of FFA derivatization, the established trimethylsilylation method presented simplicity, high specificity, and completely free from the interference of the esterified fatty acid, such as triacylglyceride. The method could be applied for analyzing FFA profiles in the clinical laboratory or pharmacological research.

基于BSTFA衍生化法白酒不挥发有机酸研究

白酒中不挥发性有机酸可能是白酒呈酸味的重要化合物,为明晰白酒原酒中不挥发性有机酸的组成与含量,采用N,O-双(三甲基硅烷基)三氟乙酰胺(N,O-bis(trimethylsilyl)trifluoroacetamide,BSTFA)衍生化结合气相色谱-质谱(GC-MS)研究白酒中不挥发有机酸,共检测到27种有机酸。通过定量这些有机酸在7种香型白酒原酒中的分布,发现羟基酸的种类最多,且总浓度最高。在检测的所有有机酸中乳酸含量最高,在几百mg/L至几个g/L之间,远远高于其他不挥发有机酸。大多数不挥发有机酸在酱香型、芝麻香型白酒中的含量较高,在清香和凤香白酒中的含量较低。

1,1,1,3,3,3-六甲基二硅氮烷与PhMe_3N^+Br_3~–选择性催化醇与酚的三甲基硅烷化反应(英文)

An efficient procedure for the trimethylsilylation of alcohols and phenols is presented.The combination of 1,1,1,3,3,3-hexamethyldisilazane and a catalytic amount of phenyltrimethylammonium tribromide(PhMe3N+Br3?) was found to be effective for the trimethylsilylation of alcohols and phenols.The protection reaction is very simple and homogenously performed in dichloromethane at room temperature and mild conditions.

天门冬氨酸催化1,1,1,3,3,3-六甲基二硅氮烷硅烷化羟基为三甲基硅醚(英文)

A wide variety of alcohols and phenols were protected as trimethylsilyl ethers using 1,1,1,3,3,3-hexamethyl disilazane catalyzed by aspartic acid as a non-toxic,metal-free,and green organocatalyst at room temperature in acetonitrile under mild and heterogeneous conditions.The procedure is operationally simple and the silylated product was obtained in high yield and purity.

{[K.18-Crown-6]Br_3}_n:A tribromide catalyst for the catalytic protection of amines and alcohols

{[K.18-Crown-6]Br3}n,a unique tribromide-type catalyst,was utilized for the N-boc protection of amines and trimethylsilylation(TMS)and tetrahydropyranylation(THP)of alcohols.The method is general for the preparation of N-boc derivatives of aliphatic(acyclic and cyclic)and aromatic,and primary and secondary amines and also various TMS-ethers and THP-ethers.The simple separation of the catalyst from the product is one of the many advantages of this method.

One-Pot Synthesis of N-Boc-2, 5-bis(trimethylsilyl)pyrrolidine

N-Boc-2, 5-bis(trimethylsilyl)pyrrolidine 4 was synthesized from the reaction of N-Boc-pyrrolidine 1 with trimethylsilyl chloride (TMSCl) at optional temperature in one-pot in good yield.

TRIMETHYLSILYLATED SILICA AS RHEOLOGY MODIFIER FOR SILICONE RESINS

Trimethylsilylated silica was synthesized. through hydrolytic condensation of tetraethoxysilane followed by trimethylsilylation. Rheological properties of the silicone resin with trimethylsilylated silica as modifier were studied. It turned out that the particle size of silica was important to the rheological behavior of the modified resin. Trimethylsilylated silica of medium particle size shows the strongest tendency of forming physical network in the resin.

Formation of multiple trimethylsilyl derivatives in the derivatization of 17α-ethinylestradiol with BSTFA or MSTFA followed by gas chromatography-mass spectrometry determination

N,O-bis（trimethylsily）trifluoroacetamide （BSTFA） and N-methyl-N（trimethylsily） trifluoroacetamide （MSTFA） are common derivatization reagents used in the GC-MS analysis of estrogen steroids such as estrone （El） and 17α-ethinylestradiol （EE2）. In this study, three trimethylsilyl （TMS） steroid derivatives, mono- and di-trimethylsilyl EE2 and mono-trimethylsilyl El, were observed during the derivatization of EE2 with BSTFA or MSTFA and/or GC separation. Factors influencing the production of multiple TMS derivatives and their relative abundance were examined. It was found that both methanol and bisphenol A competed with estrogenic esteroids when reacting with silylation reagents, and thus affected the formation of TMS derivatives and their relative abundance in the derivatization products. Methanol was found to be more reactive than bisphenol A with the BSTFA reagent. None of the three solvents tested in this study could prevent the generation of multiple TMS derivatives during the derivatization of EE2 with BSTFA, followed by GC analysis. A similar result was observed using MSTFA as the derivative reagent followed by GC analysis. Thus, the suitability of BSTFA or MSTFA as the derivatization reagent for the determination of E1 and EE2 by GC-MS, under the conditions reported here, is questionable. This problem can be solved by adding trimethylsilylimidaz （TMSI） in the BSTFA reagent as recommended, and the performance of the method has been proved in this study.

Adjusting the solvation structure with tris(trimethylsilyl)borate additive to improve the performance of LNCM half cells

Tris(trimethylsilyl)borate(TMSB) has been intensively studied to improve the performances of lithiumion batteries. However, it is still an interesting issue needed to be resolved for the research on the Li^(+) solvation structure affected by TMSB additive. Herein, the electrochemical tests, quantum chemistry calculations, potential-resolved in-situ electrochemical impedance spectroscopy measurements and surface analyses were used to explore the effects of Li^(+) solvation structure with TMSB additive on the formation of the cathode electrolyte interface(CEI) film in LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)/Li half cells. The results reveal that the TMSB additive is easy to complex with Li^(+) ion, thus weaken the intermolecular force between Li^(+) ions and ethylene carbonate solvent, which is benefit for the cycle performance. Besides, the changed Li^(+) solvation structure results in a thin and dense CEI film containing compounds with Si–O and B–O bonds which is favorable to the transfer of Li^(+) ions. As a result, the performances of the LNCM811/Li half cells are effectively improved. This research provides a new idea to construct a high-performance CEI film by adjusting the Li^(+) solvation structures.

An Efficient Way for Glycosylation of Spirostanol

Using thioglycosides as donors, trimethylsilyl trifluoromethanesulfonate (TMSOTf) and N-iodosuccinimide(NIS) as promoter, a modified procedure for the glycosylation of spirostanol was developed. A series of saponins were synthesized in mild condition with excellent yields.

Enhanced efficiency and stability in Sn-based perovskite solar cells by trimethylsilyl halide surface passivation

Lead free tin perovskite solar cells(PKSCs)are the most suitable alternative candidate for conventional lead perovskite solar cells.However,the efficiency and the stability are insufficient,mainly because of the poor film quality and numerous defects.Here we introduce an efficient strategy based on a simple trimethylsilyl halide surface passivation to increase the film quality and reduce the defect density.At the same time,a hydrophobic protective layer on the perovskite surface is formed,which enhanced the PKSCs’stability.The efficiency of the solar cell after the passivation was enhanced from 10.05%to 12.22%with the improved open-circuit voltage from 0.57 V to 0.70 V.In addition,after 92 days of storage in N_(2) filled glovebox,the modified T-PKSCs demonstrated high stability maintaining 80%of its initial efficiency.This work provides a simple and widely used strategy to optimize the surface/interface optoelectronic properties of perovskites for giving more efficient and stable solar cells and other optoelectronic devices.

Efficient oxidative deprotection of trimethylsilyl,tetrahydropyranyl and methoxymethyl ethers under solvent-free conditions

A mild, efficient and fast method for direct oxidation of trimethylsilyl, tetrahydropyranyl and methoxymethyl ethers to their corresponding carbonyl compounds using trinitratocerium（Ⅳ） bromate （TNCB） supported on NaHSO4.H2O under solvent-free conditions is reported.

THE SYNTHESES OF BENZOFURAN DERIVATIVES

Two benzofuran derivatives were synthesized from 3,4-bis(trimethylsilyl) furan after a series of reactions. Their structures were identified by 1H NMR, 13C NMR, MS and EA.

Tris(trimethylsilyl) borate as an electrolyte additive for high-voltage lithium-ion batteries using LiNi_(1/3)Mn_(1/3)Co_(1/3)O_2 cathode

The influence of tris(trimethylsilyl) borate (TMSB) as an electrolyte additive on lithium ion cells have been studied using Li/LiCo1/3Ni1/3Mn1/3O2 cells at a higher voltage, 4.7 V versus Li/Li+. 1 wt% TMSB can dramatically reduce the capacity fading that occurs during cycling at room temperature (RT) and elevated temperature (60 degrees C). After 150 cycles at 1 C rate (1 C= 278 mAh/g), the capacity retention of Li/LiCo1/3Ni1/3Mn1/3O2 is up to near 72% in the electrolyte with TMSB added, while it is only about 35% in the baseline electrolyte. The electrochemical behaviors, the surface chemistry and structure of Li/LiCo1/3Ni1/3Mn1/3O2 cathode are characterized with charge/discharge test, linear sweep voltammetry (LSV), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), thermal gravimetric analyses (TGA), scanning electron microscope (SEM) and transmission electron microscopy (TEM). These analysis results reveal that the addition of TMSB is able to protectively modify the electrode CEI film in a manner that suppresses electrolyte decomposition and degradation of electrode surface structure, even though at both a higher voltage of 4.7 V and an elevated temperature of 60 degrees C. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

Synthesis and Crystal Structure of 2-Amino-1, 1-diferrocenylethanol

Amino-1,1-diferrocenylethanol 2 was prepared by reduction of trimethylsilyl cyanohydrin ether of diferrocenyl ketone. The crystal structure of 2 was further defined by X-ray diffraction.

XPS STUDIES ON SURFACE MODIFIED POLY [1-(TRIMETHYLSILYL)-1-PROPYNE] MEMBRANES Ⅱ SURFACE MODIFICATION BY BROMINE VAPOR

Surface modification of poly [1-(trimethylsilyl)-1-propyne] (PTMSP) membranes bybromine vapor has been studied. It is shown that Br/C atomic ratio at the surfaces increased withthe time of bromination until about 60 min, then it reached a plateau. The results of XPS and IRstudies indicated that the addition of bromine to double bonds and the replacement of H on CH_3 bybromine had taken place so that a new peak at 286.0 eV (C--Br)in C_(1s) spectra and some newbands, e. g. at 1220 and 580cm^(-1) in IR spectra were formed. The fact,t Po_2, permeability ofoxygen, decreased and α_(O_2/N_2), separation factor of oxygen relative to nitrogen, increased withbromination time, shows that surface modification of PTMSP by bromine may be an efficient approach to prepare PTMSP membranes used for practical gas separations.

Studies on Glycosides(Ⅺ)──A Convenient Stereoselective Synthesis of 1-O-Aryl-α-D-glucopyranosides from Glucosyl Trimethylsilyl Ether

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FeCl₃Catalyzed One Pot Synthesis of 1-Substituted 1H-1,2,3,4-Tetrazoles under Solvent-Free Conditions

An efficient procedure for the preparation of 1-substituted-1H-1,2,3,4-tetrazoles via a three-component condensation of triethyl orthoformate, amine, and trimethylsilyl azide using inexpensive and environment-friendly FeCl3 as catalyst under solvent-free conditions has been reported. The reaction generates the corresponding 1-substituted tetrazole in excellent yields.