Acetonitrile 2-cyclohexyl-2-phenyl

Residual isocyanate monomeric extracts from 19 commercial polyurethanes were analyzed as their 9-(methylaminomethyl)anthracene derivatives on a 45°C C,g column (2 = 254 nm, ex 412 nm, em). An 80/20 ac onitrile/water (3% TEA to pH 3 with H3PO4) mobile phase was used [1024]. Analytes included 2,4- and 2,6-toluenediisocyanate, 2,4-toluene diisocyanate dimer, diphenylmethane-4,4 -diiso-cyanate, hexamethylene diisocyanate, cyclohexyl-, phenyl-, and octadecylisocyanate and, isopherone diisocyanate. The effect of varying the level of acetonitrile (70-85%) on retention (as Id) was presented as a plot for six different C,g matoiafs. Detection limits were reported as 0.03 mg/kg. 

To clean up their samples for reverse phase HPLC analysis. Van Beek and Blaakmeer (1989) investigated the use of C-18, C-8, C-2, cyclohexyl, phenyl, and CN solid phase extraction columns. No improvement of selectivity between limonin and interfering components in grapefruit juice was found. It was reported that the only difference is the elution strength of wash solvent and limonin eluent. Acetonitrile-water mixtures gave better results than methanol-water mixtures. 

Abbreviations Aik, alkyl AN, acetonitrile Ar, aryl Bu, butyl cod, 1,5-cyclooctadiene Cp, cy-clopentadienyl Cp , pentamethylcyclopentadienyl Cy, cyclohexyl dppm, diphenylphosphinome-thane dpme, Ph2PC2H4PMe2 Et, ethyl fod, 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octane-dionate HOMO, highest occupied molecular orbital LUMO, lowest unoccupied molecular orbital Me, methyl MO, molecular orbital nbd, norbornadiene Nuc, nucleophile OTf, triflate Ph, phenyl Pr, propyl py, pyridine THE, tetrahydrofuran TMEDA V,V,M,M-tetramethylethylenediamine. 

Abbreviations acac, acetylacetonate Aik, alkyl AN, acetonitrile bpy, 2,2 -bipyridine Bu, butyl cod, 1,5- or 1,4-cyclooctadiene coe, cyclooctene cot, cyclooctatetraene Cp, cyclopentadienyl Cp, pentamethylcyclopenladienyl Cy, cyclohexyl dme, 1,2-dimethoxyethane dpe, bis(diphenyl-phosphino)ethane dppen, cis-l,2-bis(di[Atenylphosphino)ethylene dppm, bis(diphenylphosphino) methane dppp, l,3-bis(diphenylphosphino)propane eda,ethylenediamine Et,ethyl Hal,halide Hpz, pyrazole HPz, variously substituted pyrazoles Hpz, 3,5-dimethylpyrazole Me, methyl Mes, mesityl nbd, notboma-2,5-diene OBor, (lS)-endo-(-)-bomoxy Ph, phenyl phen, LlO-phenanthroline Pr, f opyl py, pyridine pz, pyrazolate Pz, variously substituted pyrazolates pz, 3,5-dimethylpyrazolate solv, solvent tfb, tetrafluorobenzo(5,6]bicyclo(2.2.2]octa-2,5,7-triene (tetrafluorobenzobanelene) THE, tetrahydrofuran tht, tetrahydrothicphene Tol, tolyl. 

A new parameter space for the synthesis of silsesquioxane precursors was defined by six different trichlorosilanes (R=cyclohexyl, cyclopentyl, phenyl, methyl, ethyl and tert-butyl) and three highly polar solvents [dimethyl sulfoxide (DMSO), water and formamide]. This parameter space was screened as a function of the activity in the epoxidation of 1-octene with tert-butyl hydroperoxide (TBHP) [26] displayed by the catalysts obtained after coordination of Ti(OBu)4 to the silsesquioxane structures. Fig. 9.4 shows the relative activities of the titanium silsesquioxanes together with those of the titanium silsesquioxanes obtained from silsesquioxanes synthesised in acetonitrile. The values are normalised to the activity of the complex obtained by reacting Ti(OBu)4 with the pure cyclopentyl silsesquioxane o7b3 [(c-C5H9)7Si7012Ti0C4H9]. 

The highest catalytic activities were found for the titanium complexes obtained from tert-butyl silsesquioxanes synthesised in DM SO and water, with respectively 84% and 74% of the activity of the reference catalyst (c-C5H9)7Si7012Ti0C4H9. [With the experimental conditions employed, (c-C5H9)7Si7012Ti0C4H9 gives complete and selective conversion of TBHP towards the epoxide therefore, the relative activities of the reported catalysts correspond to their TBHP conversions towards 1,2-epoxyoctane.] These two catalysts exhibited almost the same activity as the previous best HTE catalyst (87%) obtained from cyclopentyl silsesquioxanes synthesised in acetonitrile [39, 44, 46] and are the first reported examples of tert-butyl silsesquioxanes as precursors for very active titanium catalysts. Relevant catalytic activities were also obtained with cyclohexyl silsesquioxanes synthesised in DM SO (67%) and with phenyl silsesquioxanes synthesised in H20 (61%). 

It is of interest to note that by substituting alkyl bromides for cyclohexyl bromide the corresponding a-phenyl-a-alkyl-acetonitriles are obtained, which may be hydrolysed to the a-phenylaUphatic acids thus with ethyl iodide a-phenyl-butyronitrile is produced, hydrolysed by ethanolic potassium hydroxide to a-phenylbutyric acid. 

Abbreviations aapy, 2-acetamidopyridine Aik, alkyl AN, acetonitrile Ar, aryl Bu, butyl cod, 1,5-cyclooctadiene COE, cyclooctene COT, cyclooctatetraene Cp, cyclopentadienyl Cp, penta-methylcyclopentadienyl Cy, cyclohexyl DME, 1,2-dimethoxyethane DMF, dimethylfonnaniide DMSO, dimethyl sulfoxide dmpe, dimethylphosphinoethane dppe, diphenylphosphinoethane dppm, diphenylphosphinomethane dppp, diphenylphosphinopropane Et, ethyl Fc, fetrocenyl ind, inda-zolyl Me, methyl Mes, mesitylene nb, norbornene or bicyclo[2.2.1 ]heptene nbd, 2,5-norbomadiene OTf, triflate Ph, phenyl PPN, bis(triphenylphosphoranylidene)ammonium Pr, propyl py, pyridine pz, pyrazolate pz, substimted pyrazolate pz, 3,5-dimethylpyrazolate quin, quinolin-8-olate solv, solvent tfb, tetrafluorobenzobatrelene THE, tetrahydrofuran THT, tetrahydrothiophene tmeda, tetramethylethylenediamine Tol, tolyl Tp, HB(C3H3N2)3 Tp, HB(3,5-Me2C3HN2)3 Tp, substituted hydrotris(pyrazol-l-yl)borate Ts, tosyl tz, 1,2,4-triazolate Vin, vinyl. 

Reversed phase (Cu, Cg, C4, C2, phenyl, diphenyl, cyclohexyl, cyano-propyl) for nonpolar analytes (alkyl, aromatic) in polar solutions (water, aqueous buffers), with high to medium polarity eluents (methanol, acetonitrile, water)... 

Solvent exchange at the [M(PR3)2(solv)2H2] cations, with M = Rh or Ir, R = phenyl or cyclohexyl, solv = acetone or acetonitrile, have been followed by proton nmr spectroscopy, with the establishment of rate constants and Arrhenius parameters. The most marked feature is the enormous acceleration induced by the trans effect of the hydride ligand, taking these reactions from the normal very slow rates characteristic of rhodium(III) and iridium(III) into the nmr time scale. Rates are considerably faster for... 

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