Experimental section

Methylphenidate (Ritalin) was fortified in human urine samples and extracted by liquid-liquid extraction. A trideuterated analogue of methylphenidate (methylphenidate- ) was used as an internal standard for the analysis. The detailed sample preparation procedure is described elsewhere.13 The final samples containing both methylphenidate and methylphenidate- were in 75% methanol, 25% water and 0.1% formic acid. 

Equation 11.14. Titanium catalyzed tandem hydroamination/hydrosilylation of aminoalkynes [133]. 

As already mentioned, there has been significant progress in the development of chiral catalysts for asymmetric hydroamination reactions over the last decade. However, significant challenges remain, such as asymmetric intermolecular hydro aminations of simple nonactivated alkenes and the development of a chiral catalyst, which is applicable to a wide variety of substrates with consistent high stereochemical induction and tolerance of a multitude of functional groups as well as air and moisture. Certainly, late transition metal based catalysts show promising leads that could fill this void, but to date, early transition metal based catalysts (in particular, rare earth metals) remain the most active and most versatile catalyst systems. 

The addition of water or alcohols to alkenes is readily catalyzed by Bronsted acids. The hydroamination reaction constitutes the analogous process using amines. Why do adds commonly not catalyze this process  

The addition of aniline to the enantioenriched allene ( ) I is known to proceed with excellent regio and stereoselectivity to give II in good yield in presence of a robust gold catalyst  

Tlie following mechanisms can be envisioned for this reaction 

Otherwise noted, 2% (wt/wt) solutions were utilized for study. Spin-spin coupling constants are given in Hz V(C, F) is normally taken to be a negative 

Amic acids (AA) were prepared by two different methods. Stirring appropriate mixtures of amine and anhydride overnight in NMP yielded solutions of the desired amic acid suitable for F-NMR studies, hi order to discern a crude isomer composition, -C-NMR was performed on compounds prepared by a literature procedure utilizing chloroform as a solvent. This technique gave very high yields of very high-purity monoamic acid as the materials precipitated from the reaction mixture. 

Synthesis of many of the imide model compounds has been described previously. 44-46 i3C-NMR data for compounds described here for the first time are summarized in Table 17.1. Those carbon atoms not numbered on the 4-FA part of the amic acid model compounds occurred at approximately the same chemical shifts regardless of the nature of the anhydride residue. 

Characterization. The high resolution TEM images were obtained on a JEOL 2010 electron microscope with an acceleration voltage of 200 kV. Measurement of nitrogen adsorption-desorption isotherms was performed on a Micromeritics ASAP 

2010 system. Before each measurement, the samples were degassed at 200°C for 2 h. The pore size distribution was calculated by using the Horvath-Kawazoe (HK) method. 

IR spectra of the samples with and without pyridine were recorded on an FT-IR spectrometer (PE 430) with a resolution of 1 cm. In order to measure the pyridine adsorption, the samples were pressed into thin pellets, and placed into a quartz cell with CaF2 windows. The sample pellets were evacuated at 400°C for 2 h ( 10 Torr). After cooling down to room temperature, the pellets were exposed to pyridine environment (10 Torr) at 25°C. IR spectra were recorded after adsorption of pyridine for 1 h and evacuation at 150, 250, 350, and 450°C for 1 h. 

TPD-NH3 curves were obtained in a temperature range of 120 to 600°C, at a rate of 15°C/min. The adsorption of ammonia onto the sample was carried out at 25°C. Subsequently, the removal of ammonia was performed at 500 or 550°C for 1 h by purging air or pure nitrogen. Blank runs were carried out under the same conditions but with no NH3 adsorbed. The TPD-NH3 curves were obtained after subtraction of the blank run. 

Reagents used in the preparation of starting materials, procedures, and instrumentation have been described earlier (24,25). 

In a typical experiment 0.8 mL portions of solutions made from 0.029 g (p-pdt)[Fe(CO)2(PMe3)]2 in 1 mL CH2C12 were placed in medium-pressure NMR sample tubes (Wilmad, 528 -PV-7) together with 2 pL H20. The tubes were degassed, pressurized with 10 bar D2 and exposed to sunlight as shown in Fig. 2. 2H NMR spectra were taken at time intervals to follow the formation of HOD. 

NMR shielding tensors were calculated using the Gauge-Independent Atomic Orbital (GIAO) method as implemented in Gaussian 98 (44-46). The basis sets and level of theory are the same as used in the geometry optimizations and frequency calculations mentioned above. 

Materials. The LCPs 1-4 and low molecular weight analogues 5-8 which we consider in detail have the molecular structures shown in Fig. 13. The Greek letters, , p, 8, and pp, refer to five different derivatives of the same LC, deuteriated at different sites of the mesogen or alkyl chain, as indicated in the formula of LCP 4. Synthetic 

crysL system Mol. wt length Phase trans. temperatures VK dealing oithalpy AHJ(kJmol ) Clearing entropy ASJ(Jmol- K- ) 

ESR Measurements. The side chain LCPs 1 and 2 and the corresponding low molecular weight analogue 5 were studied by dynamic ESR techniques [35]. The weight fraction of the CSL spin probe employed was 10 . Sample cells were constructed of two quartz plates coated with tin dioxide to make them conducting. The thickness of the cell was 250 pm. 

Computatioiis. A Fortran program package, based on the theoretical approach outlined in the previous section, was employed to analyze the ESR and NMR expai-ments. The programs simulate dynamic magnetic resonance experiments of nitroxide rascals and spin probes undergoing inter- and intramolecular motion in an aniso- 

TaHe 2. Constant Parameters Used in the Calculations of ESR spectra of Cholestane Spin Probes in Liquid Crystal Side Chain Polymers and Low Molecular Weight Analogues 

All anhydride and amine compounds were of the highest quality commercially available. Aniline (AN) was distilled imder reduced pressure phthalic anhydride (PA) was sublimed and stored under anhydrous conditions. High-quality NMP (BASF) was stored over molecular sieves. All other reagents were used as received from commercial sources as follows 4-fluoroaniline (4-FA) (99%, Aldrich Chemical Co.), 3-fluorophthalic anhydride (3-FPA) (Fluorochem Ltd.), 2,2- bis(3,4-carboxyphenyl)hexafluoropropane dianhydride (6FDA) (monomer grade, Hoechst) 2,2-bis(4-aminophenyl)hexafluoropropane (6FDM) (99%, Chriskev Co., Inc.), l,l -bis(3,4-carboxyphenyl) sulfone dianhydride (SDA) (99%, Chriskev Co., Inc ), 1,1 -oxydiphthalic anhydride (ODPA) (Occidental Chemical Co.), (4-aminophenyl)phenyl ether and 4-aminophenylben-zophenone (Aldrich Chemical Co.). 

Synthesis of many of the imide model compounds has been described previously. C-NMR data for compounds described here for the first time 

The polymers used in this study are PAG granulate and PA4.6 granulate, as produced by DSM, see Table 9.1. The PAG and PA4.6 granules were chopped into pieces before measurement. Demineralized water and ethanol were used in the experiments. 

Carbonic acid, (2J ,3S,6S)-3,6-Dihydro-6-[(4-methoxyphenyl)melhoxy]-2-methyl-2H-pyran-3-yl methyl ester (103) To a stirred solution of allylic alcohol 102 (20 g, 80 mmol), pyridine (38.8 ml, 480mmol), and DMAP (1.96 g) in dry CH2CI2 (400ml), methyl chloroformate was added dropwise (33.9 ml, 480 mmol) at 0 °C. After reacting for 1 h at 0 °C, water (300 ml) was 

AD-mix-a 3equiv KjFelCN)JKjCOj, lequiv MeS02NH2, 5% OsO, and6%(DHQ)2PHAL 

AD-mix-P 3equiv K,Fe(CN)JK,CO lequiv MeSO NH, 5% OsO, and6%(DHQD)2PHAL 

We are grateful to NIH (GM090259) and NSF (CHE-0749451) for their support of our research programs. MFC also acknowledges the NSF for his fellowship from the NSF-ICERT Nanomedicine Program (DCE-0965843) at Northeastern University. 

For reviews of other approaches to hexoses, see (a) Gijsen, H.).M., Qiao, 

All reactions were carried out under Ar in solvents dried using a Solvent Purification System (SPS). Extractive workup refers to portioning of the crude reaction between an organic solvent and water, phase separation, drying (Na2S04 or MgS04), and evaporation under reduced pressure. 

NMR spectra were recorded at 23 °C on a Bruker Advance 400 Ultrashield apparatus. 

Mass spectra were recorded on Waters LCT Premier (ESI) and Waters GCT (El, Cl) spectrometers. Elemental analyses were performed on a LECO CHNS 932 micro-analyzer at the Universidad Complutense de Madrid. Melting points were determined using a Biichi melting point apparatus. Optical rotations were recorded on a P-1030 polarimeter from Jasco at the sodium D line. 

General Procedure. Merrifield s resin (1.1 mmol Cl/g, 1% crosslinker divinylbenzene copolymer, 70-90 mesh) was obtained from Aldrich Chemical Co. MacroKans were obtained from IRORI. ° FT-IR characterizations of the polymer-supported reactions were carried out by placing ca. 10 mg of the polymer-supported material on a NaCl plate. After the beads were swollen with 2-3 drops of CCI4, a second NaCl plate was pressed onto the beads, and an FTIR spectrum was recorded. 

Thioacetic acid S- 4-[3-fIuoro-4-(4-phenylethynylphenyIethynyl-phenylethynyljphenyl ester (12b). 75 mg (43%) of 12b was produced 

Thioacetic acid S- 4-[4-(3-cyano-4-phenylethynylphenylethynyl) 3-fIuoro-phenyIethynyl]phenyl ester (14b). 62 mg (42%) of 14b was 

All chemicals were reagent grade and were used without further purification. Infrared spectra were recorded on a JASCO FT/IR-350 spectrometer. Mass spectra were measured using a JEOL JMS-TIOOLP. Elemental analyses were performed on a Yanaco CHN corder MT-6. Inductively coupled plasma (ICP) emission spectroscopy was performed on a Shimadzu lCPE-9000. Thermogravimetric analyses were performed on a MAC TG-DTA 2000 in an argon atmosphere at a heating rate of 1 °C min .  

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Excellent results are obtained by passing acetone vapour over an electrically heated nichrome wire spiral an apparatus, incorporating the latter, is described in the experimental section. 

In determining the values of Ka use is made of the pronounced shift of the UV-vis absorption spectrum of 2.4 upon coordination to the catalytically active ions as is illustrated in Figure 2.4 ". The occurrence of an isosbestic point can be regarded as an indication that there are only two species in solution that contribute to the absorption spectrum free and coordinated dienophile. The exact method of determination of the equilibrium constants is described extensively in reference 75 and is summarised in the experimental section. Since equilibrium constants and rate constants depend on the ionic strength, from this point onward, all measurements have been performed at constant ionic strength of 2.00 M usir potassium nitrate as background electrolyte . 

During 1974—1985, about 200 sulfur—asphalt roads were constmcted worldwide, half of which were ia the United States. AH U.S. SEA experimental sections designed and constmcted according to standard practices usiag standard materials are performing as well as the control sections of conventional asphalt ia these experimental projects (49). 

Naturally, neither of these approximations is valid near the border between the two regions. Physically sensible are only such parameters, for which b < 1. Note that even for a low vibration frequency Q, the adiabatic limit may hold for large enough coupling parameter C (see the bill of the adiabatic approximation domain in fig. 30). This situation is referred to as strong-fiuctuation limit by [Benderskii et al. 1991a-c], and it actually takes place for heavy particle transfer, as described in the experimental section of this review. In the section 5 we shall describe how both the sudden and adiabatic limits may be viewed from a unique perspective. 

There have also been reports of adding zinc chloride or tin chloride to the Morgan-Walls conditions to catalyze the reaction (see experimental section). ... 

The formation of 2-bromoethylsulfonate followed the method described in "Organic Syntheses" (21). In the attempt to generalize this reaction, we noted that neither 1,3-dibromopropane nor 1,4-di-bromobutane was miscible in the ethanol-water reaction solvent. Directly following the described procedure did produce both the 3-bromopropylsulfonate and 4-bromobutylsulfonate, but in low yields of roughly 20%. Improved procedures for alkylation were developed using acetonitrile as the solvent. The yields of the reactions for both III and IV with the ethyl, propyl, and butyl bromosulfonates are given in the "Experimental section. 

These reactions are useful because they run under mild conditions, use inexpensive or easily recoverable starting materials, and have short reaction times. The major problem in purification is the separation of the sodium pyridone sulfonate from excess sodium sulfite, sodium bromide, and sodium bromoalkyl sulfonate. However, these latter compounds usually would not interfere with the use of the pyridone sulfonate as a water tracer. From a practical point of view, the pyridone sulfonates need not be purified, but can be used directly. A modified synthetic procedure involves the treatment of the pyridone sodium salt with a tenfold excess of a,iu-dibromoalkane in acetonitrile, followed by removal of the excess dibromide by vacuum distillation. The resulting product is treated with an excess of sodium sulfite in aqueous ethanol. Evaporation of the solvent yields a useful tracer. Procedures given in the experimental section were... 

Limits of Detection. A signal-to-noise ratio of 2 could be obtained from 5pL of a 10 if solution of pyridone I, under the conditions described in the "Experimental" section. This amount of the solution... 

Van Urk s reagent as 4-(dimethylamino)-benzaldehyde - sulfuric acid, but the experimental section incorrectly refers to a solution of 4-(dimethylamino)-benzaldehyde in hydrochloric acid/ethanol as Van Urk s reagent [1]. 

Method A, the Agitated Ampoule Technique, and Method B, the Static Mixer Method, are described below in the experimental section. 

Extreme caution should be exercised in preparing hexachlorodibenzo-p-dioxins under the conditions described in the Experimental section the product seems to form during controlled exotherms at 325°C. The suspected toxicity of this material and possible experimental flaws could place the experimenter in danger. 

Figure 6. Effect of palytoxin on the rate of Na influx in Swiss 3T3 cells. Confluent quiescent Swiss 3T3 cells were incubated for 37 C for 7 min in incubation media containing 0.1 pM PTX, 1.1 pM PTX, or 11 pM PTX. Intracellular Na was determined as described in the Experimental section. Data points represent the mean of quadruplicate points.

The situation that no charge transfer across the interface occurs is named the ideal polarized or blocked interface. Such interfaces do not permit, due to thermodynamic or kinetic reasons, either electron or ion transfer. They possess Galvani potentials fixed by the electrolyte and charge. Of course, the ideal polarizable interface is practically a limiting case of the interfaces with charge transfer, because any interface is always permeable to ions to some extent. Therefore, only an approximation of the ideal polarizable interface can be realized experimentally (Section III.D). 

Figure 4.2 Cascade catalysis using centrifugal contact separators in series. Experimental section...

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