Methods, miscellaneous

Here we mention briefly some methods whose applicability in the study of inorganic substances is more limited than those already covered this may be because they can be applied only to a very limited number of samples, or because the information - valuable though it may be - is less varied. 

Many would disagree with the consignment of mass spectrometry to this section and would argue that it deserves a section to itself. Until fairly recently, this technique was restricted to volatile, molecular substances and was therefore obviously of much less interest to inorganic chemists than to their organic colleagues. 

For example, samples of animal tissue can be investigated without the need to isolate any specific substance. This has been used to study the bonding of platinum atoms in animal organs, following the administration of platinum complexes as anti-tumour agents. 

This is a difficult technique, unfamiliar to most inorganic chemists and of limited applicability. However, in the hands of a small band of enthusiasts, it has produced results of real value. 

The status of Mossbauer spectroscopy is akin to that of NQR. It is restricted to solids, and it yields information about the electronic and chemical environment about certain nuclei. Where diffraction methods are inappropriate, Mossbauer may be the best technique for structure determination. 

We discuss in this section some methods that do not fall into a common category but are nonetheless important in soil studies. More methods can be found in the ample literature (Sparks 1996, 1998 Sumner 1999 Wilkinson and Lead 2007 Klute 2010). 

In this category, we have grouped together aU those methods that, while not being intrinsically less valuable or important than those previously discussed, have only been used in a very small number of cases during the last 6 years for the preparation of 5,6-dihydropyran-2-ones [6]. 

4) cycloisomerization of y,S-epoxy-a,fi-enals catalyzed by N-heterocychc carbenes (NHC) [43], 

Another competing reaction is the intermolecular replacement of bromine by hydrogen in the radical translocating group. Additional approaches capitalizing on stereospecific hydrogen translocation to the anomeric radical have been described by Crich [186, 187]. Despite excellent stereoselectivity, the radical approach is rendered impractical by the circuitous methods needed for generation of the key anomeric radical [51]. 

The reaction of white phosphorus with a mixture of 2,4,6-tri(t-butyl)bromobenzene and 2,4,6-tri-(t-butyl)phenyllithium 

The chlorination of 3,5-dimethylisoxazole gave the 3,4-dichloro-4-isoxazoline (489) (77MIP41602). Additional 2-substituted 4-isoxazolines were prepared by the addition of nitrones to triple bonds (76AP1014, 77H(8)387, 70CB3196, 67AG(E)709, 69CB2346), as shown by the conversion of (490) into (491) (76AP1014). 

The rearrangement of fused triazole (493) produced a fused aziridine and a fused 4-isoxazoline (494) (75T831). 

Eremenko and co-workers used nitryl fluoride for the deamination of amines at subambient temperatures in acetonitrile. The same reaction occurs with primary nitramines and their alkali metal salts bis-nitramines react to give the corresponding bis-nitrate esters. 

The reaction of primary aliphatic amines and nitramines with nitronium salts also leads to deamination and the formation of alkyl nitrates. 

Katritsky and co-workers ° reacted primary amines with the triflate salt of 5,6,8,9-tetrahydro-7-phenyl-dibenzo[c, /tjacridine to generate the corresponding A -substituted acri-dinium triflate salts, which on refluxing in dioxane in the presence of benzyltrimethylammo-nium nitrate, yield the corresponding nitrate esters. 

Radical bromination with NBS can result in the replacement of a sugar ring hydrogen by bromine.18 These reactions can be highly regioselective 

Lithium (phenylthiocyclopropylcuprate) 185, prepared by the reaction of cuprous thiophenolate with cyclopropyllithium in THF at —78 °C, was added to p-iodo-enones. For example, treatment with 3-iodo-2-cyclohexen-l-one 186 provided the corresponding P-cyclopropyl a,P-unsaturated ketones 187 with high efficiency, Eq. (59) 127). 

Otherwise, cuprous iodide-catalyzed addition of methylmagnesium iodide to 2-cyclohexen-l-one in ether at 0 °C, followed by trapping of the resultant enolate anion 188 with cyclopropanecarboxaldehyde 189, afforded the two diastereomers of the cyclopropylcarbinol 190 a. Further transformation into the corresponding acetates 190b (acetic anhydride, pyridine), followed by treatment with l,5-diazabicyclo[4.3.0]-non-5-ene (DBN) in refluxing benzene, provided in 78 % yield, a mixture of the desired P-cyclopropyl enones 191 and 192, in a ratio of 13 1, Eq. (60) 127). 

In analogy to the preparation of the cyclopropanone hemiacetal 3 (vide supra, Eq. (1)7), reductive cyclization of the piperidide of 3-chloropropionic acid 193 with sodium in ether in the presence of ClSiMe3, gave the 1-piperidino-l-trimethylsilyloxy-cyclopropane 194 a which was converted to the cyclopropanol 194 b upon treatment with methanolic tetrabutylammonium fluoride. Both 194 a and 194 b can be used for the ready generation of cyclopropane derivatives thus the silyl ether 194a could be reacted directly with the vinylic Grignard reagents 195 to provide the vinyl cyclopropane derivative 196, (Eq. (61)128). 

Furthermore, treatment of 194 a, b with potassium cyanide in the presence of aqueous acetic acid gave the cyclopropylnitrile 197 in 62-73% yield. This nitrile was then allowed, to react with cyclopropyllithium in ether at —78 °C to give the cyclopropyl ketimine 198, Eq. (62)129). 

While the nucleophilic addition of 1-lithio-l-bromocyclopropanes to ketones gave oxaspiropentanes, precursors of 1-donor substited vinylcyclopropane derivatives vide supra, Sect. 4.5, Eq. (28)), addition of n-BuLi at low temperature to 1,1-di-bromocyclopropane 199 (prepared in 75 % yield from the addition of dibromocarbene 

Similarly, the reaction of aryl Grignard reagents with arynes, prepared in situ from 2-fluorophenyllithium, gave after iodolysis sterically encumbered substituted 2-iodobiphenyls.86 

Some alkyl or alkenylmagnesium compounds were obtained via carbometallation or ring-opening reactions with other Grignard reagents. These methods are described in the sections dedicated to the addition to multiple bonds or 

There are a few examples of the the formation of aminoorganotin(IV) compounds from diamino- or diorgano-tin(II) compounds. The tin(II) diamine (16-1) can be alkylated with ethyl bromide or iodide to give the ethyltin halide diamides (16-2).23 

The diarylstannylene (16-3) reacts with mesityl azide to give the distannaaziridine (16-4), which in solution is in equilibrium with the stannaimine (16-5) and stannylene, and this mixture reacts with further azide to give the distannaazetidine (16-6).24 

The 15N NMR parameters of organotin compounds have been reviewed by Wrack- 

In most of the reactions of the stannylamines, the NR2 group acts as a mild nucleophile in substitution or addition reactions. 

When Nu-E is a protic acid (E = H), the substitution reactions provide a route to various new types of organotin compound. In the addition reactions, the heterocumulenes (CO2, RN=C=0, RN=C=NR etc.) constitute an important group of acceptor molecules Nu-E. There are also a few reactions which involve homolytic cleavage of the Sn-N bond. 

A piezoelectric crystal coated with methyltrioctylphosphonium dimethylphosphate has been recently described as a good detector for phosgene in air [1976], The sensitivity of this device is in the range of 1-35 p.p.m. 

An indirect method for the analysis of phosgene in phosgene/carbon dioxide mixtures involves passage of the gases over metallic silver at 800 C. This induces decomposition according to equation (3.6), and the phosgene is estimated by analysing for the CO [1375]. 

Quantitative analysis of a mixture of HCl and COClj has been achieved by condensing the mixture onto solid diphenylmercury(II) the HCl is converted quantitatively to benzene [464]. 

In one commercially-available gas analyser [2093a], COClj is determined after its thermal hydrolysis to HCl in a small furnace, at temperatures in excess of 7(X) C. Although capable of measuring phosgene concentrations in the sub-p.p.m. region, many other gases interfere in this technique [2093a]. 

Clearly, the preferred method to use for the analysis of phosgene depends upon the particular application to hand. For routine use in the laboratory, for monitoring the ambient air, impregnated paper strips and Dra ger tubes can be recommended as both reliable and easy to use. On the plant, automatic methods for continuous analysis would be appropriate, and one of the electrical or automated spectroscopic techniques would be suitable. For accurate measurement of very low (p.p.b.) concentrations however, a gas chromatographic procedure using one of the special detectors is most suitable. 

Metallation of the methyL group of the configurationally stable, chiral, -tolyl(methyl)sulphoxide, followed by treatment with chlorodiphenylphosphine, has given the chiral phosphine (54).  

A metal template effect has been utilised in the synthesis of the 

Various three-and four-membered phosphorus-arsenic ring systems, e.g., (58), have been isolated from the reactions of aryldichloroarsines with bis(trimethylsilyl)phosphido complexes of 

2 Cross-coupling of Organoboron Compounds with Organic Halides 

Organoboronic acids or their esters are generally stable to air and thermal treatment. Thus, the boronic esters can be isolated by distillation, and acids by crystallization. 

Instrumentation. The experimental setup is similar to that employed for in situ X-ray diffraction. The material under investigation is pressed into a thin sheet and mounted together with suitable counter and reference electrodes into a silica cell. In order to decrease the large incoherent scattering contributions from protons in aqueous electrolyte solutions, deuterated solutions are used. In a typical study, the reaction mechanism of Ni(OH)2 (employed in nickel accumulators) was studied with neutron powder diffraction NPD [46]. A direct and continuous structural transformation of both the y- and jS-NiOOH phases into j8-Ni(OH)2 was observed during reduction with no direct relationship or discontinuity related to the transition from the first discharge electrode potential to the second one, which was located about 0.4 V lower. 

Taguchi, H. Yamamoto, and H. Nozaki, Bull. Chem. Soc. Japan, 1977, 50, 1592. 

Stork and Williard have noted that when certain olefinic a,/8-epoxy-ketones are treated with hydrazine in methanol, conditions normally resulting in the Wharton reaction, anomalous behaviour resulting in cyclization is observed.Thus the epoxy-ketone (185) was converted into the bicyclic alcohol (186) in 85% yield. 

Although five-membered rings are produced in preference to six-membered rings the latter can be formed in the same way by selection of a suitable substrate. Unfortunately the process cannot be applied to all epoxy-ketones, and the factors preventing cyclisation, although presumed to be geometric, as yet remain obscure. 

The photo- RNl reaction of enolate anions with aryl halides has been shown to be useful for both inter- and intra-molecular annelation reactions, but has now been found to suffer one major drawback in its general applicability. When a hydrogen atom is present at the /8-carbon of the enolate anion, hydrogen atom transfer to the transient phenyl radical is the preferred reaction pathway. 

Finally, Becker has successfully applied the intramolecular Wittig reaction to the construction of bicyclo[m, ,0]alk-l-enes (m, n = 3, 4, or 5) (187) and strained methylene-bridged bicyclic systems, e.g. (188).  

Recently, Zhu et al [100] exploited PAMAM dendrimers to tag the target strand which increase the Ret on hybridization with surface immobilized capture strand. The A Ret can easily distinguish dsDNA without PAMAM tag, mismatched and non-complementary sequences from PAMAM tagged complementary ds-DNA with picomolar sensitivity (Fig. 7.17). 

Watanabe et al. [101] detected DNA mismatches through a strand exchange reaction in which the duplex consisting of a capture probe and a redox-labeled probe strand are immobilized on 

De Napoli, G. Di Fabio, A. Messere, D. Montesar-chio, A. Romanelli, G. Piccialli, and M. Varra, Tetrahedron 14435 [1999], 

Okahata M. Kawase, K. Niikura, I. Ohtake, H. Furusawa, and Y. Ebara, Chem. Commun. 470 [2002). 

Wojciechowski, R. Sundseth, M. Moreno, and R. Henkens, Clin. Chem. 1690 [1999). 

Blast mining (sometime referred to as conventional mining) is an older practice in which explosives (such as dynamite) are used to fracture the coal seam, after which the coal is gathered and loaded on to shuttle cars or conveyors for removal to a central loading area. This process consists of a series of operations that begins with cutting the coal bed so it will break easily when blasted with explosives. 

Retreat mining is a method in which the pillars or coal ribs used to hold up the mine roof are extracted, allowing the mine roof to collapse as the mining works back toward the entrance. This is one of the most dangerous forms of mining owing to imperfect predictability of when the ceiling will collapse and possibly crush or trap workers in the mine. 

Inlrared spectroscopy and H-NMR have been used occasionally to identify and to quantify residual solvents, but their sensitivity is rather limited if compared with GC. On the other hand specificity is not always assured. The solvent should display signals well separated fi om those arising firom the product, which is not always the case. 

In addition to its wide substrate scope and functional group compatibility, the Meerwein-Eschenmoser-Claisen rearrangement is marked by high regio- and stereoselectivity, notably in the case of acydic substrates. In fact, the reaction provides some of the best examples for acyclic stereocontrol reported in the literature. 

Epoxy groups have also been determined spectrophotometrically using 2,4 dinitrobenzene sulfonic acid [66] and by the Zeisel method [67-69]. 

Tsushima et al. (2010) developed an MRI system to investigate the effects of relative humidity (RH) and current density on the transverse water content profile in a membrane under fuel cell operation at a practical PEMFC operating temperature. The MRI visualization revealed that in dry conditions (40% RH), the membrane hydration X number was 3, and the water content profile in the membrane was fiat because the diffusion process in the membrane was dominant in the water transport. In a standard condition (80% RH) the water content in the membrane was 8, and a partial dehydration at the anode was observed at a current density of 0.2 A/cm, indicating that electroosmosis was influential. At the higher RH level of 92%, the water content X within the membrane at 0.2 A/cm was around 22, corresponding to the eqnilibrium state of the membrane in liquid water, and the water content profile with the increase in current density became fiat. This indicates that the liquid water generated in the cathode catalyst layer permeated the membrane, where water transport plays a more dominant role. 

An important requirement for PEMFC stacks is the uniformity of reactant flow rate through all cells of the stack. Sekine et al. (2010) proposed a nondestructive method for measuring the flow distribution between cells applicable to an actual PEMFC stack that does not contain an embedded sensor. The principle of the 

EXPERIMENTAL METHODS FOR INVESTIGATING FUEL CELL STACKS 

Matic H., A. Lundblat, G. Lindbergh, P. Jacobsson, Electrochem. Solid-State Lett., 8, A5 

Scheiba F., N. Benker, U. Kunz, C. Roth, H. Fuess, J. Power Sources, 177, 273 (2008). Schneider A., C. Wieser, J. Roth, L. Helfen, J. Power Sources, 195, 6349 (2010). 

The one-carbon ring homologation of cycloalkanones is readily accomplished, following treatment of the corresponding silyl enol ethers with Simmons-Smith reagent and reaction of the resulting silyloxybicyclo[ ,l,0]alkane (192) with FeCl3 

Catalytic cyclizations of polyenes can be achieved using DIBAL in mineral oil, e.g. (193) (194), (195) - (196), and cycloalkanes are obtained from terminal 

Magnetic susceptibility x, for the as-grown P(Py) fihns synthesized at -30—40 C. PF closed squares, AsFj open squares, BF/ closed diamonds, CIO open circles, ToS closed diamonds. The closed circles and the open diamonds are PF and TsO obtained by SQUID. After Reference [531], reproduced with permission. 

Representative comparison of applied potential (top) and QCM data (bottom) for a P(Py)/PSS film in aqueous NaC104. After Reference [91], reproduced with permission. 

Appendix 1 One Illustrative Networic-Analyzer Based Calculation ofMicrowave 

The scattering parameters S, and Sji, which are automatically error-corrected in the Automated Network Analyzer (ANA), are measured as a function of frequency. The complex permittivity e and the permeability p are calculated from the measured S-parameters, using a modification of the Nicolson-Ross method, as summarized below. 

Let r and T be the reflection and transmission coefficients due to the sample, of thickness d. The aiuilysis is robust in that the thickness d need not be precisely known. Defining a parameter 

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Miscellaneous Methods At the beginning of this section we noted that kinetic methods are susceptible to significant errors when experimental variables affecting the reaction s rate are difficult to control. Many variables, such as temperature, can be controlled with proper instrumentation. Other variables, such as interferents in the sample matrix, are more difficult to control and may lead to significant errors. Although not discussed in this text, direct-computation and curve-fitting methods have been developed that compensate for these sources of error. ... 

Miscellaneous Methods. Exhaustive evaluation of the decarbonylation of ben2oyl duorides, ArCOF, by Wilkinson s catalyst [14694-95-2] Rh[(CgH )2P]3Cl, to give aryl duorides has estabUshed (81) that previous claims (82) caimot be reproduced. 

Miscellaneous Methods. Powdered metals such as aluminum, chromium, nickel, and copper, along with various aHoys, can be appHed to parts by electrostatic deposition. The metal strip containing the attached powdered metal must be further processed by cold rolling and sintering to compact and bond the metal powder. 

E. Miscellaneous methods. Exchange reactions between the tetracyano-nickelate(II) ion [Ni(CN)4]2 (the potassium salt is readily prepared) and the element to be determined, whereby nickel ions are set free, have a limited application. Thus silver and gold, which themselves cannot be titrated complexometrically, can be determined in this way. 

Miscellaneous methods. Other techniques, although used much more rarely, can sometimes be helpful. Among these techniques dynamic thermochemical analysis295, measurements of electric conductivity297, of ultrasonic absorption298, and of dielectric constant299,300 should be mentioned. 

In general, tetrazolium salts are prepared by (a) oxidation of formazans and (b) alkylation of tetrazoles. Therefore, synthetic methods for formazans and tetrazoles are discussed first, followed by some direct and miscellaneous methods. 

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