Syntheses and Properties

Satsumabayashi and J. Nakayama, Nippon Shika Daigaku Kiyo, Ippan Kyoiku-kei, 1981, 10,155 Chem. Abstr., 1981, 95, 80 797). 

Valentiny, A. Martvon, and P. Kovac, Collect. Czech. Chem. Commun., 1981, 46, 2197. 

Omar and F. A. Sherif,/ndian/. Chem., Sect. B, 1981, 20, 849 (Chem. Abstr., 

No major differences in the mass-spectral behaviour between the sulphur-and selenium-containing compounds have been observed. The predominant form in the tautomerism of A -thiazolin-4-ones/thiazolidin-4-ones depends in part on the 5-substituent. Thus the condensation of 2-amino-A -selenazolin-4-ones (196) with RCHO (R = Ph, 4-CIC6H4, 2,4-Cl2C6H3, or 

Synthesis and Properties.—The major limitation in the use of oxysulphonium ylides is the shortage of ylides other than the methylide. Virtually no progress has been made on this problem in the past two years, other than in the case of some very stabilized ylides. For example. Dost and Gosselck have expanded the reaction of stable diazo-compounds with DMSO to afford stable and isolable oxysulphonium ylides (58). 

Johnson et have published the full details of their unique and potentially expandable method for the preparation of the oxysulphonium-methylide (59). The ylide is stable and may be stored in solution for two months. Although such results have not been reported to date, it seems possible to utilize a variety of alkylphenyl sulphides as starting materials and thereby obtain higher alkylides. 

Schmidbaur and Kammel have prepared a series of ylides similar to (59) and examined their properties in detail. The ylides were colourless, stable, 

Kunieda and Witkop have reported the cleavage of a substituted oxysulphonium ylide (62) with Raney nickel in the presence of other 

Synthesis and Properties.—Polythiazyl was prepared by the solid state polymerization of SjNj, which is itself first formed by the thermal decomposition of S4N4, The (SN)n crystals which result from this process are shiny, brass-coloured, and have typical dimensions of a few millimetres. To date, even the best crystals produced are highly imperfect. The polymerization mechanism and the origin of the defect structure has been discussed, but it is clear that further work is required to understand the nature and elimination of these crystal imperfections. 

The electrical conductivity of (SN)n (room temperature) is in the range 1200—3700 S cm- (/.e. similar conductivity to mercury and bismuth), and is increased to a magnitude of 50—200 times this value when the temperature is reduced to 4.2 K. When the temperature is further lowered to 0.26 K, (SN) becomes superconducting. (SN)b is believed to be the first example of a new class of materials, termed polymeric molecular metals, and recent work has 

Bernard, A. Herold, M. Lelaurain, and G. Robert, Compt. rend., 1976, 283, 625. 

Synthesis and Properties.—Perhaps the most interesting new compound that might be included in this section is the non-ylidic F4S=CH2 (1), a colourless, stable gas that boils at —19 °C and has been synthesized as shown. The carbon chemical shift of 43.9 p.p.m. is very different from that for phosphonium ylides, suggesting that there is little negative charge on the carbon atom in (1). Carbon is sp -hybridized and the barrier to rotation about the C=S bond (estimated bond order is 1.9) is greater than 25kcalmol this precludes free rotation at room temperature. 

The first X-ray structure of a thiabenzene derivative, i.e. l-benzoyl-2-methyl-2-thianaphthalene, has been reported. The geometry is similar to that of open-chain benzoyl-stabilized ylides with pyramidal sulphur. Other studies point to the ylidic character of 9,10-diphenyl-10-thia-anthracene . N.m.r. data, including C n.m.r. chemical shifts, have been presented for indole-3-sulphonium ylides and carbonyl-stabilized sulphonium ylides and their Pd complexes. Infrared spectra of cr-nitrosulphonium ylides have been analysed. Further details have been provided of a study of the pyramidal inversion of unstabilized sulphonium ylides (see Chap. 5, pp. 243 and 251). 

Reactions.—In Volume 5 (p. 74), an example of the formation and alkylation of a sulphonium ylide anion was given. Another example (4) has now been described,  

Semenov and S. A. Shevelev, Izv. Akad. Nauk SSSR, Ser. Khim., 1978,2355. 

Kataoka, H. Shimizu, S. Ohno, K. Narita, H. Takayanagi, H. Ogura, and Y. litaka. Tetrahedron Lett., 1979,4315. 

Synthesis and Properties.—The two most general methods for preparing sulphonium ylides continue to be a-deprotonation of a sulphonium salt and the reaction of a sulphide (or disulphide with a carbene. A new development involves the reaction of the thianthrene or phenoxathiin cation radical with a dicarbonyl compound, e.g. ethyl benzoylacetate, to give (4). An infrequently used but useful route to sulphonium ylides involves reaction of sulphides e.g. dithia[3,3]cyclophanes with benzyne. A detailed description of a preparation of the sulphonium salt precursor to Trost s diphenylsulphonium cyclopropylide has appeared. The selectivity of ylide formation in the reaction of cyclic and acyclic sulphides with carbenes has been examined and compared with the much 

Thiabenzenes are best represented as cyclic ylides rather than species with aromatic ring currents involving through-sulphur delocalization. Thia- 

Among the novel sulphonium ylides synthesized in this period are (8), (9) (which is unusually basic), (10), McgS—CHPO(OMe)2, EtMeS—C=CHS-MeEt (a cumulated ylide), and (11).  

Reactions.—The reaction of sulphonium ylides with carbonyl compounds to form oxirans is now a standard reaction. Among the more unusual examples reported are an intramolecular version directed towards the preparation of arene epoxide (12) (not isolable), the synthesis of the epoxide of 8-phenylthio-methylenecycloheptane, and the direct conversion of a diketone by dimethyl-sulphonium methylide into a doubly homologated hydroxymethyl aldehyde (13) by the rearrangement shown.  

A second common reaction of sulphonium ylides is Michael addition to ajS-unsaturated carbonyl compounds, giving cyclopropanes. This reaction forms the basis of a cyclopentene synthesis starting from sulphonium allylide (14). Other recent examples include the preparation of spiro[cyclopropane-l,4-A -pyrazolin]-5 -one derivatives (15) and cyclopropyl-ulose (16). Un- 

Synthesis and Properties.—Oxysulphonium ylide chemistry still suffers from the lack of a variety of simple, high-yield syntheses of the precursor 

Sugimura, K. lino, I. Kawamoto, and Y. Kishida, Chem. Letters, 1972, 1085. 

Full details now have appeared regarding the reactions of diazo-com-pounds with sulphoxides to form oxysulphonium ylides, a method analogous to that employed for sulphonium ylides. The reaction, in the presence of cuprous cyanide, seems effective only with disubstituted diazomethane in which both substituents are strongly electron-withdrawing. Dimethyloxysulphoniumcyclopentadienylide was prepared by this method from diazocyclopentadiene and DMSO. 

Whereas sulphonium phenacylides are thermally decomposed to cyclopropanes, an oxysulphonium phenacylide gave (84) when heated in the presence of cupric sulphate. Heating (85) in the absence of any catalysts gave (86), probably via a 2,3-sigmatropic rearrangement and sulphoxide elimination to afford a diene, which was attacked at the a, 3-bond by a second molecule of ylide.  

The synthesis and properties of Li, Mg, Al, and Cr perchlorate hydrazines are discussed here [24,30]. 

Method I Magnesium perchlorate hydrazine, Mg(Cl04)2(N2H4)2 is prepared by the addition of hydrazine hydrate to an aqueous solution of magnesium perchlorate hexahydrate (2 1 ratio, respectively) at room temperature. The reaction is almost instantaneous and the solid compound is precipitated by the addition of alcohol (90% product yield)  

Method II Magnesium perchlorate hydrazine can also be prepared by the reaction of stoichiometric quantities of magnesium powder with ammonium perchlorate dissolved in hydrazine hydrate (1 2 2 ratio, respectively) at room temperature. Magnesium metal dissolves exothermically with the evolution of hydrogen. The solid compound is obtained by the addition of alcohol ( 96% yield)  

Mg 2NH4CIO4 2N2H4-H20 Mg(C104)2(N2H4)2 2NH3 -H H2 -H 2H2O 

Diperchlorate Dihydrazine Chromium(III) Perchlorate Diperchlorate dihydrazine chromium(III) perchlorate, [Cr(C104)2(N2H4)2] CIO4, is prepared by the addition of alcoholic hydrazine hydrate to an aqueous solution of chromium(ni) perchlorate. The reaction is instantaneous with the formation of a crystalfine violet compoimd [32]. 

While the chemical properties of GNPs were first studied by Faraday, the main application of gold colloids in the biomedical field has been related to their electronic and optical properties [8, 9]. At present, there are many synthetic routes to 

2 Functionalization of GNPs with Bioactive Compounds and Biomedical Applications of Functionalized GNPs 

Pavlov et al. developed a method to amplify the detection of thrombin in solution and on a surface using GNPs functionalized with an aptamer (the aptamer recognizes thrombin) as a catalytic label for the amplification [17]. Aptamer 1, (5 -HS-(CH2)9-TTTTTTTTTTTTTTTGGTTGGTGTGGTTGG-3 ), was covalently 

Figu re 3.4 Amplified detection of thrombin on surfaces by the catalytic enlargement of thrombin aptamer-functionalized GNPs. (Reprinted with permission from Reference [17], Copyright 2007 American Chemical Society.) 

Transmission electron microscopy (TEM) images showed that GNPs conjugated with Tat peptide (nuclear localization sequence) were mainly located in the nucleus of fibroblast and also revealed no appreciable cytotoxic effects [22]. In contrast, Tkachenko et al. functionalized GNPs with four different nuclear localization peptides ending with a Cys residue (which contains a free thiol) to evaluate the cellular trajectories of peptide gold complexes. Functionalized GNPs were 

Jc(J K) greater than 10 A/cm. Jc(H) shows weak field dependence indicating an absence of weak-link behavior. For the films of different orientation discussed here the Tc values are of the order of 84-85 K for the two-domain a-axis films, 86-87 K for the c-axis film and aligned a-axis films, and 88 K for the (103) films. 

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Vartuli J C, Roth W J, Beck J S, McCullen S B and Kresge C T 1998 The synthesis and properties of M41S and related mesoporous materials Moiecuiar Sieves Science and Technoiogy vol 1, ed FI G Karge and J Weitkamp (Berlin Springer) pp 97-119... 

Since then, the fundamental physicochemical aspects of the synthesis and properties of ev anines have been exhaustively reviewed by Heseltine and Stunner in the fourth edition of Mee s treatise (3) and by Sturmer in Weissberger s edition of the Chemistry of Heterocyclic Compounds (4). So the purpose of this section dealing especially with thiazolomethine dyes is to give, apart from a complete and recent list of dyes and references, a description of the particularities of their chemistry and chiefly of the reaction mechanisms involved in their synthesis that have remained unknown or have not been discussed until now. 

I ovolac Synthesis and Properties. Novolac resins used in DNQ-based photoresists are the most complex, the best-studied, the most highly engineered, and the most widely used polymers in microlithography. Novolacs are condensation products of phenoHc monomers (typically cresols or other alkylated phenols) and formaldehyde, formed under acid catalysis. Figure 13 shows the polymerization chemistry and polymer stmcture formed in the step growth polymerization (31) of novolac resins. 

Synthesis and Properties. Several methods have been suggested to synthesize polyimides. The predominant one involves a two-step condensation reaction between aromatic diamines and aromatic dianhydrides in polar aprotic solvents (2,3). In the first step, a soluble, linear poly(amic acid) results, which in the second step undergoes cyclodehydration, leading to an insoluble and infusible PL Overall yields are generally only 70—80%. 

Synthesis and Properties. Polyoxadia2oles containing aromatic moieties with aUphatic linkages/groups have been widely explored in the hterature. The aromatic moieties increase the rigidity of the polymer the presence of aUphatic groups makes the chain more flexible and processible. 

Synthesis and Properties. A number of monomers have been used to prepare PQs and PPQs, including aromatic bis((9-diamines) and tetramines, aromatic bis(a-dicarbonyl) monomers (bisglyoxals), bis(phenyl-a-diketones) and a-ketones, bis(phenyl-a-diketones) containing amide, imide, and ester groups between the a-diketones. Significant problems encountered are that the tetraamines are carcinogenic, difficult to purify, and have poor stabihty, and the bisglyoxals require an arduous synthesis. 

Synthesis and Properties. Polyquinolines are formed by the step-growth polymerization of o-aminophenyl (aryl) ketone monomers and ketone monomers with alpha hydrogens (mosdy acetophenone derivatives). Both AA—BB and AB-type polyquinolines are known as well as a number of copolymers. Polyquinolines have often been prepared by the Friedlander reaction (88), which involves either an acid- or a base-catalyzed condensation of an (9-amino aromatic aldehyde or ketone with a ketomethylene compound, producing quinoline. Surveys of monomers and their syntheses and properties have beenpubhshed (89—91). 

Synthesis and Properties. In 1972, Du Pont marketed a series of linear aromatic polyimides called NR-150 (105) based on... 

Synthesis and Properties. Several polymers containing HFIP-O groups have been investigated, the most common beeing epoxies and polyurethanes. The development of fluorinated epoxy resins and the basic understanding of their chemistry has been reviewed (127). 

Synthesis and Properties. The synthesis of (21) follows a very straightforward route based on readily accessible starting materials and on some novel reactions ia organo—inorganic sulfur chemistry (83—85), as well as on polycondensation chemistry analogous to that utilized ia the preparation of poly(alkyl/arylphosphazenes). One preparation of (21) is as follows ... 

Trifluoromethyl Derivatives of the Transition Metal Flements 1984 Synthesis and Properties of Aryl... 

Ruonne-Contairung Cyclohexadienones Synthesis and Properties Kobnna, L S, Shteingarts, V D J Fluorine Ckem 41, 111-162 122 n... 

Tire synthesis and properties of azafulvalenes are covered in a comprehensive review by Professor R. Beckert (Friedrich Schiller University, Germany). 

Thiopyran and thiopyrylium salts synthesis and properties 98MI18. 

Synthesis and properties of analogs of nucleic acids 95MI10. 

Sulfur-containing macroheterocycles synthesis and properties 98Mtl6. 

Synthesis and properties of carborane-containing organophosphorus compounds 97UK1125. 

Of these, the 2(5//)-furanones 2 are perhaps the compounds having the most interesting synthetic and biological importance. The synthesis and properties of compounds 2 have recently attracted much attention. The 2(5//)-furanone fragment is present in a wide variety of biologically active natural products (84MI1) moreover these furanones possess utility as valuable synthetic intermediates (86T3715). 

Ameduri, B. and Boutevin, B. Synthesis and Properties of Fluorinated Telechelic Monodis-persed Compounds. Vol. 102, pp. 133-170. 

Masuda, T. and Higashimura, T. Poly acetylenes with Substituents Their Synthesis and Properties. Vol. 81, pp. 121 — 166. 

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