Experimental Selected Procedures

Catalytic amounts of [Pd(PPh3)4] (chiffres ) and Cul were added to a solution of dithienophosphole 80 (1.73 g, 1.5 mmol) and l,4-diiodo-2,5-bis(octyloxy)benzene (0.88 g, 1.5 mmol) in N-methylpyrrolidinone (80 mL). The light-yellow reaction mixture was then stirred for 48 h at 200 °C, after which time the color changed to orange-red. The solution was then cooled to room temperature, the solvent evaporated under vacuum and the resulting amorphous solid taken up in a small amount of THF (ca. 5 mL). The suspension was filtered, precipitated into hexane and the residue dried under vacuum to yield 80 as a reddish brown pow- 

for example, (a) http //www.ko-dak.com/US/en/corp/display/in-dex.jhtml (b) http //www.research.phi-lips.com/technologies/display/ (c) http //www.dupont.com/displays/oled/ (d) http //www.cdfltd.co.uk/ (e) http // www.universaldisplay.com/ (f) http // www.covion.com/index.html. 

Mathey, Phosphorus-Carbon Heterocyclic Chemistry the Rise of a New Domain, Elsevier Science, Oxford, 2001 (b) K. Dillon, F. Mathey, J.F. Nixon, Phosphorus the Carbon Copy, Wiley, Chichester, 1998 (c) L. Nyulaszi, Chem. Rev. 2001, 303, 1229 (d) F. Mathey, Angew. Chem. Int. Ed. 2003, 42, 1578. 

Hissler, T. Karpati, J. Rault-Berthelot, V. Deborde, L. Toupet, L. Nyulaszi, R. Reau, J. Am. Chem. Soc. 

Granell, D. Velasco, F. Lopez-Calahorra, Tetrahedron Lett. 2001, 42, 7791 (b) E. Duran, D. Velasco, F. Lopez-Calahorra, H. Finkel-mann, Mol. Cryst. Liq. Cryst. 2002, 383, 43. 

In a well-ventilated hood a 2-L, two-necked, round-bottom flask is equipped with a magnetic stirring bar, stopper, and a pressure-equalizing dropping funnel fitted with a gas inlet T-tube connected to a mineral oil bubbler. The flask is flushed with nitrogen and charged with 150 mL of dry dichloromethane and 60.0 g (0.141 mol) of 126. The mixture is stirred and cooled to -78°C in a dry-ice/2-propanol bath, and 23.9 g (0.141 mol) of 1-trimethylsiloxycy-clohexene is added dropwise over a few minutes. The mixture is stirred at — 78 C for 4 h. After the solution is warmed to room temperature, dichloromethane is removed under reduced pressure and replaced with 400 mL of acetone. The dark-red solution of the alkyne complex is cooled to —78 °C and 175 g (0.32 mol) of ceric ammonium nitrate is added in portions. The mixture is stirred until the gas evolution (carbon monoxide ) ceases (ca. 4 h). The reaction mixture is warmed to room temperature, poured into 1 L of saturated brine solution, and extracted with four 250-mL portions of diethyl ether. The combined ether extracts are dried over magnesium sulfate, filtered, and concentrated on a rotary evaporator. The residual red oil is distilled at reduced pressure to afford 15.0-15.2 g (71-72%) of 127 as a pale-yellow liquid, bp 57-60°C (10 mm). 

We thank Dr. A. J. M. Caffyn for assistance in coverage of the chemistry of propargylium complexes [16]. We are grateful for financial support of our research in this area provided by the National Institutes of Health and the Petroleum Research Fund (A. C. S.). 

HOMO/LUMO highest occupied MO/lowest unoccupied MO 

While the number of transition-metal-promoted cycloadditions of acetylenes is quite large 

In his initial paper in 1975, D6tz reported that the thermal cycloaddition of pentacar-bonyl(methoxyphenylcarbene)chromium with diphenylacetylene in di-n-butyl ether yielded a chromium-complexed 4-methoxy-l-naphthol [2]. Soon thereafter, he related that the same reactants in w-heptane produced not only naphthol product, but also indene, furan, and cyclobutenone products [4]. As it turned out, these results foreshadowed the extraordinary richness of organic structural types that may be derived from cycloadditions of alkynes with Fischer carbenes, as well as very recent contributions to reaction chemoselectivity through control of reaction conditions. Indeed, in the years since, the field has seen the introduction of a number of newly discovered cycloaddition types and, maybe more importantly, has 

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This book covers comprehensively all aspects of the subject related to organobismuth chemistry in a self-contained manner. However, it is focused on academic aspects and consequently the references include a limited numbers of patents that are mentioned only where pertinent to the description. Chapter 1 serves as an introduction to bismuth as the element. In Chapters 2-4, organobismuth compounds are classified according to the types of compounds and dealt with in detail. Chapter 5 is devoted to the use of bismuth and derivatives in organic transformations. In these four chapters, brief to moderate descriptions for selected experimental procedures are included they are intended to inform the readers of relevant protocols and should serve in preparative studies which are based on analogies. In the final chapter the X-... 

Only intermediates that are formed before the rate-determining step can accumulate. Reactions where intermediates can be isolated in a normal work up are rather rare. More often, intermediates might be observable by spectroscopic techniques. The existence of short-lived intermediates or of intermediates occurring after the rate-determining step can still be demonstrated by trapping reactions or by special techniques such as matrix isolation. This chapter provides detailed explanations of reaction mechanisms involving carbanions, possible transition states, and the scope of the reactions. The selected experimental procedures can be implemented quickly and easily in the laboratory. 

R. J. Sundberg, Indoles (1996), Academic Press, London. An excellent review covering the gamut of methods, including selective experimental procedures. 

Experimental. Select experimental procedures for the preparation of the representative Ar-Ar and Ar-Z-Ar derivatives are provided in Section 14.6. 

Several general synthetic routes towards transition metal alkynyls have been developed in the past few decades. Some of the most commonly employed methods are discussed below while selected experimental procedures are summarized at the... 

The selection of the operating principle and the design of the calorimeter depends upon the nature of the process to be studied and on the experimental procedures required. Flowever, the type of calorimeter necessary to study a particular process is not unique and can depend upon subjective factors such as teclmical restrictions, resources, traditions of the laboratory and the inclinations of the researcher. 

Designing an experimental procedure involves selecting an appropriate method of analysis based on established criteria, such as accuracy, precision, sensitivity, and detection limit the urgency with which results are needed the cost of a single analysis the number of samples to be analyzed and the amount of sample available for... 

Following the movement of airborne pollutants requires a natural or artificial tracer (a species specific to the source of the airborne pollutants) that can be experimentally measured at sites distant from the source. Limitations placed on the tracer, therefore, governed the design of the experimental procedure. These limitations included cost, the need to detect small quantities of the tracer, and the absence of the tracer from other natural sources. In addition, aerosols are emitted from high-temperature combustion sources that produce an abundance of very reactive species. The tracer, therefore, had to be both thermally and chemically stable. On the basis of these criteria, rare earth isotopes, such as those of Nd, were selected as tracers. The choice of tracer, in turn, dictated the analytical method (thermal ionization mass spectrometry, or TIMS) for measuring the isotopic abundances of... 

SELECTIVE OXIDATIONS OF HYDROXY STEROIDS / 243 EXPERIMENTAL PROCEDURES... 

Ring-contraction methods described in this chapter have been selected from the many examples reported in the literature on the basis of outstanding reliability and utility. When several adequate methods are available for accomplishing the same transformation only one, and hopefully the best, experimental procedure is presented. The author admits a predilection for methods which in his own experience have proved useful. 

Independent reference and validated methods by selected expert analysts - multiple organizations and laboratories Two or preferably three or more independent reference and/or validated methods, each based on an entirely conceptually different principle of measurement, independent in theory and experimental procedure, applied in replicate, by selected expert analysts, of high reputational quality and recognized competence working independently in an ad... 

A facile method for the oxidation of alcohols to carbonyl compounds has been reported by Varma et al. using montmorillonite K 10 clay-supported iron(III) nitrate (clayfen) under solvent-free conditions [100], This MW-expedited reaction presumably proceeds via the intermediacy of nitrosonium ions. Interestingly, no carboxylic acids are formed in the oxidation of primary alcohols. The simple solvent-free experimental procedure involves mixing of neat substrates with clayfen and a brief exposure of the reaction mixture to irradiation in a MW oven for 15-60 s. This rapid, ma-nipulatively simple, inexpensive and selective procedure avoids the use of excess solvents and toxic oxidants (Scheme 6.30) [100]. Solid state use of clayfen has afforded higher yields and the amounts used are half of that used by Laszlo et al. [17,19]. 

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