摘要:

The reaction of E-glass short fibers with tert-butyldiphenylchlorosilane (TBDPCS) and trimethylchlorosilane (TMCS) was studied by FTIR spectroscopy in water and in toluene. Fiber coating obtained from TMCS in aqueous solution contained siloxane bonds, by which the trimethylsilyl group was attached to the glass surface. Coatings obtained from TBDPCS, however, consisted of silane and silanol, and no siloxane bonds were observed. This may be attributed to the effect of steric hindrance in the reaction.

ISSN:0038-7010    

DOI:10.1080/00387019108018144

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Owing to its great importance as a structural link in proteins, the NH-CO amide group has been the subject of numerous experimental and theoretical investigations. In contrast, the -NH-COO-carbamate group has been re atively ignored despite its importance in biologically ac ive molecules such as local anaesthetics1–2. U p to now, no experimental studies concerning the proton acceptor ability of carbnmates have appeared in the literature. It must be pointed out however thnt ab initio calculations were carried out for the interaction between simple carbarnates and model molecules such as N- methylacetamide or phenol3. In this work, the complexes between N-methyl methyl-carbamate (MMC) and N,N-dimethyl methylcarbamate (DMMC) and model proton donors (phenol derivatives) are studied by IR or FT-IR spectroscopy

ISSN:0038-7010    

DOI:10.1080/00387019108018145

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Adsorbtion isotherms, from water solution onto activated carbon have been determined over a wide consantration range for phenol and some its derivatives. At the first look, it was observed that the experimental data of 3-hydroxyphenol (resorsine) agree with predicted isotherm calculated by the Hansen-Facker modification of Polanyi Adsorption Potential Theory, using only the solute refractive index and molar volume, together with characteristic curve for the carbon as determined from gas-phase adsorption data but, 4-nitrophenol isotherm agree with the theoretical isotherm after correction for its hydration and corrected experimental curves of phenol, 2, 4-dinitrophenol and 2,4,6-trinitrophenol appear to be related to the theoretical isotherm by single abscissa scale factor.

ISSN:0038-7010    

DOI:10.1080/00387019108018146

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Through the synthesis of a model compund and the use of a15N NMR spectroscopic titration together with13C and1H NMR the site of protonation of 2-methoxypyrazine has been determined to be N4.

ISSN:0038-7010    

DOI:10.1080/00387019108018147

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

It is suggested that the term, a, describing the difference between gas phase and solid state XPS data is related to the molar polarizability P by the general expression a = b p−1/3 + c From previously obtained values of the parameters b and c (b= 8.30 eV cm mol−1/3and c= 4.15 eV) we can derive the binding energy of gaseous carbon atoms, Eb= 296.4 eV. The close agreement with the experimentally found Eb= 296.2 eV is regarded as a validification of the above-mentioned formula and also of the concept of atomic charge.

ISSN:0038-7010    

DOI:10.1080/00387019108018148

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A quartz reaction vessel is designed and constructed to interface HPLC and cold-vapor AA for mercury speciation in aqueous samples. Inorganic mercury, methyl mercuric and ethyl mercuric compounds can be separated effectively within 10 minutes. An on-line preconcentration unit is used to reduce the limit of detection (LOD) before the sample is introduced into the reversed-phase HPLC. Without preconcentration, the detection limits for the three mercury species are 0.094, 0.085 and 0.124 ppm, respectively. Limits of detection are reduced to 0.78, 0.78 and 0.42 ppm, with the use of preconcentration technique. The feasibility of this method is tested by analyzing mercury compounds in synthetic tap and river water samples.

ISSN:0038-7010    

DOI:10.1080/00387019108018149

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

A complete vibrational assignment of the i.r. and Raman bands of several substituted Schiff bases and their Fe(III) complexes has been done. On this basis, a tentative type of structure for complexes is proposed. The influence of the electron donor-acceptor characteristics and size of substituents on the structure of ligands and complexes is discussed.

ISSN:0038-7010    

DOI:10.1080/00387019108018150

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Infrared spectra were obtained for 1,2-dibromopropane-d6in the liquid and in the unannealed and annealed solid states. Vibrational assignments were made for the three conformers of 1,2-dibromopropane and the three conformers of 1,2-dibromopropane-d6with the aid of normal coordinate calculations. All three possible conformers of CD2BrCDBrCD3were found to be present in the liquid and unannealed solid, but the PHSHHconformer was absent in the annealed solid.

ISSN:0038-7010    

DOI:10.1080/00387019108018151

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Natural abundance17O NMR chemical shift data for 12 variably hindered aryl acid chlorides recorded in acetonitrile at 75° C are reported. The17O NMR signals for the hindered acid chlorides are deshielded relative to unhindered isomers. A quantitative relationship between molecular mechanics (MM2) estimated torsion angles and17O NMR chemical shifts for the aryl acid chlorides is developed.

ISSN:0038-7010    

DOI:10.1080/00387019108018152

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Long range inter—ring “zig—zag” coupling between C-4 and H-8 (J48−1.5 to −1.8 Hz) has been observed in some 2,4− and 2,3,4− haloquinolines at 75 MHz. The coupling is influenced by the 4-halo substituent.

ISSN:0038-7010    

DOI:10.1080/00387019108018153

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor