Alkyl and aryl derivatives

Alkyl and Aryl Derivatives.—Reactions of organometallic reagents, such as methyl-lithium, with fluorocyclophosphazenes are, in general, 

Kajiwara and H. Saito, Kogyo Kagaku Zasshi, 1970, 73, 1947 (Chem. Abs., 1971, 

The stepwise replacement of fluorine atoms in fluorocyclophosphazenes, (NPF2) n = 3—5), by methyl groups has been followed.and n.m.r. spectroscopy showed that methyl-lithium in diethyl ether generally effects a geminal replacement pattern. With N3P3F6, only mono- and di-methyl derivatives were obtained, but with N4P4F8 the dimethyl (52), trimethyl (53), and octamethyl derivatives were noted. The formation of 

A detailed description of the experimental aspects of the preparation of the fluorophenylcyclotriphosphazatrienes (56) and (57) has been given, 

Alkyl and Aryl Derivatives.—No new routes to alkyl-substituted cyclophosphazenes have been described, although trimeric and tetrameric homologues can be inter-converted on heating 

The equilibration is accelerated by acids and inhibited by bases. In no case were substantial quantities of higher homologues or polymers obtained, and their absence was discussed in relation to interconversions between rings and polymers in halogenophosphazene, dimethylsiloxane, dimethylsilthiane, and polysulphur species. 

New arsenic-containing heterocycles (104) have been synthesized/ using reaction (14). In addition, a hydrochloride of (104 R =R =Ph) was isolated which contains 

Alkyl and Aryl Derivatives.—Potassium amide has been shown to cleave benzyl groups from phosphorus in liquid ammonia at 120 °C  

Kajiwara, H. Saito, and T. Saito, Nippon Kagaku Kaishi, 1973, 1432 Chem. Abs., 1973, 79, 126 889w). 

The resulting pyrophoric potassium salt is of interest since it contains an aza-analogue of the phosphate anion. Further, this salt may be converted into a pyrophosphate analogue, formulated as K6[(HN)2(N=)PNHP(=N)(NH)2], in liquid ammonia. 

The cleavage of the Si—N bond in iV-silylphosphazenes generally provides a versatile means of changing the iV-substituents. However, reactions with chloro-phosphines are more complex in that a rapid quatemization step may occur, e.g. 

Many new examples of these salts have now been reported, including cases where quatemization was accomplished by chloro-arsines to give salts of the 

Alkyl and Aryl Derivatives.—The cleavage of silicon-nitrogen bonds in A-silylphosphazenes by reactions with phosphorus and silicon halides has been studied in some detail. For example, with phosphorus trichloride a novel tri(phosphazenyl)phosphine is obtained  

A similar reaction occurs with dichloromethylphosphine, but with chlorodimethylphosphine an unexpectedly facile quaternization reaction occurs, so that the A-dimethylphosphinophosphazene, Me3P=N-PMe2, is not observed  

MegP N-SiMea + MePClg MeaP N-SiMcg + McaPCl 

An analogous result is observed with the sulphur imide Me2S(0)=N SiMes Me2S(0)=N SiMe3 + MCaPCl -------------------- Me2S(0)=N(PMc2)2 Cl- 

The chemical shifts of these salts suggest that the phosphonium ions are stabilized by conjugation between the phosphazenyl groups and the central phosphorus (P+) atoms. 

All known alkyl and aryl quinolizinium salts have been produced by ring synthesis there are no reports of direct alkylation of an already formed quinolizinium salt. Alkyl and aryl groups (2-furyl is the only reported ex- 

By contrast, compounds (65) undergo methylation at the nitrogen atom to give (66).140 The quaternary salts (66) were also isolated with BPh4 or SbCl6- anions. 

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Very small quantities of bismuthine are obtained when a bismuth-magnesium alloy, BijMgj, is dissolved in hydrochloric acid. As would be expected, it is extremely unstable, decomposing at room temperature to bismuth and hydrogen. Alkyl and aryl derivatives, for example trimethylbismuthine, Bi(CHj)3, are more stable. 

Thiophene [110-02-1] and a number of its derivatives are significant in fine chemical industries as intermediates to many products for pharmaceutical, agrochemical, dyestuffs, and electronic appHcations. This article concentrates on the industrial, commercial, and economic aspects of the production and apphcations of thiophene and thiophene derivatives and details the main synthetic schemes to the parent ring system and simple alkyl and aryl derivatives. Functionalization of the ring and the synthesis of some functional derivatives that result, not from the parent ring system, but by direct ring cyclization reactions are also considered. Many good reviews on the chemistry of thiophene and thiophene derivatives are available (1 7). 

The glycidyl adducts are skin irritants similar in behaviour in this respeet to the parent amines. The skin sensitisation effects in the primary aliphatic amine may be reduced by addition of groups at the nitrogen atom. The hydroxyethyl group and its alkyl and aryl derivatives are the most effective found so far. 

It is notable that the preparation of alkyl and aryl derivatives from Pb starting materials always results in Pb organometallic compounds. The only well-defined examples of Ptf ... 

Stabilization of /j -alkyl and -aryl derivatives of transition metals can be enhanced by the judicious inclusion of various other stabilizing ligands in the complex, even though such ligands are known not to be an essential prerequisite. Particularly efficacious are potential IT acceptors (see below) such as AsPh3, PPh3,... 

Studies of die structures of cuprate species were initiated to elucidate die niedi-anisnis by wbidi tliey interact witli substrates and to understand dieit special reactivities. tn die early days tliese investigaiions were restricted to solution studies by spectroscopic tediniques. It was not until 1982 dial tlie dtst example of a cuprate species - [iCu Pbi-jiLiiTHFj))] - was stiuctutally diatacterlzed by X-tay crystal stiucture deterniination [ 100] ivide infra). It sbotild be noted tliat most of diese studies, reviewed previously [29, 45, 101], were limited to "simple" alkyl and aryl derivatives. 

Metal hydrides of Groups 13 (IIIA) and 14 (IVA) of the periodic table (e.g., AIH3, GaH3) as well as many of their alkyl and aryl derivatives (e.g., R2AIH, Ar3SnH) add... 

Alkali Metal Derivatives of Metal Carbonyls, 2, 1S7 Alkyl and Aryl Derivatives of Transition Metals, 7, 1S7 Alkyl cobalt and Acylcobalt Tetracarbonyls, 4, 243 Allyl Metal Complexes, 2, 32S... 

Addition of Alkyl and Aryl Derivatives To illustrate stereoselective syntheses in nucleophilic reactions of nitrones, the synthesis of (+ )-lentiginosine... 

Allene (1) and its alkyl and aryl derivatives have long been used in organic synthesis, especially in cycloaddition reactions, whether these are thermally [5] or photochemi-cally induced and involve metal catalysis or polar reagents [2], Potentially more interesting derivatives arise when the allene group is connected with other unsaturated building blocks as shown in Scheme 5.1. 

The stereochemistry of the dimerization is complex and has been studied for numerous alkyl and aryl derivatives.] [117,121]. 

Alkyl and Aryl Derivatives.—Compounds of this type are limited to the synthesis of a second bis(cyclotriphosphazenyl)-derivative [Scheme 14, compound (62)] containing a P—P bond.139 The crystal structure of (62) confirmed the presence of a P—P bond (see also Section 8). It is known that compound (64) is methylated by methyl iodide. 

Alkyl and aryl derivatives of poly(dichlorophosphazene) are not efficiently synthesized by nucleophilic reaction of LXXXIV with metal alkyls or aryls. The halogen substitution reaction occurs but is accompanied by polymer chain cleavage. Use of poly(difluorophosphazene) or introduction of aryl and alkyl groups at the monomer stage offer some improvement, but neither method is fully satisfactory. The best route to alkyl and aryl derivatives is polymerization of A-(trimethylsilyl)-/).P-dialkyl-.P-halophosphoranimines at moderate temperatures (25-60°C) in the presence of a Lewis acid [Allcock et al., 1996, 2000, 2001a,b Neilson and Wisian-Neilson, 1988]. The reaction proceeds as a cationic chain polymerization ... 

Acyl substituents at the 3- and/or 4-positions result in decreased hydrolytic stability compared with the alkyl and aryl derivatives described above. Despite this constraint most of the usual reactions of the carbonyl group are possible. Aldehydes <9ILA1211> and ketones are oxidized to the carboxylic acid, borohydride reduction affords the expected alcohols, and epoxides are formed on reaction with diazomethane. Oximes and arylhydrazones are formed with hydroxylamine and arylhydrazines, and the products may subsequently undergo monocyclic rearrangement involving the oxadiazole to give the corresponding isomeric furazans and 1,2,3-triazoles (Section 4.05.5.1.4). 

Bromoanions, irivalent uranium, 34 98-99 Bromo complexes, osmium, 37 297-299 Bromocuprates(I), 37 39 Bromocyclophosphazene alkyl and aryl derivatives, 21 43 synthesis, 21 43, 44... 

Like the inorg compds of the azido acid, and unlike the alkyl and aryl derivs, the guanidine salt is photosensitive. In the dark it may be stored below 10°, in vacuo, for days without appreciable decompn. On long standing at RT, the salt decomps quanty, yielding Na, sulfur and guanidine thiocyanate. In aq soln the azido salt reacts with AgNOs to form the insol Ag azidodithiocarbonate... 

Table 6-3.—Electric Dipole Moments of Alkyl and Aryl Derivatives...

As with the alkyl and aryl derivatives of the pyrrolenines and indolenines, a tautomeric equilibrium has also been noted between the pentachloro-2//- and -3H- pyrroles, such that when the 2//-pyrrole, produced by chlorination of 2,3,4,5-tetrachloropyrrole or of 3,4-dichloromaleimide, is allowed to react with dienophiles, the adducts are those formed by cycloaddition with the 3H-pyrrole tautomer (Scheme 84) (80JOC435, 80JA7862, 81JOC3036). Cycloaddition with cyclopentadiene occurs on the 2H-pyrrole, which behaves as the dienophile. 

IR spectral data for most known 1,2,4-triazines have been published. The absorption of the 1,2,4-triazines in the IR region are those expected for this system. The IR spectrum of the parent compound (1) shows three absorption bands for the C—H stretching vibrations at 3090, 3060 and 3030 cm-1, five bands for C=N and C=C stretching vibrations at 1560, 1529,1435,1380 and 1295 cm-1, three for the C—H in-plane deformations at 1163,1135 and 1113 cm-1, two for the characteristic ring skeleton vibrations at 1050 and 995 cm-1 and three bands for the C—H out-of-plane deformation vibrations at 851,768 and 713 cm-1 (68CB3952). These values are in good agreement with similar bands for pyridine, pyridazine, pyrimidine and pyrazine. Alkyl and aryl derivatives of 1,2,4-triazine show similar bands in their IR spectra, with additional bands from the substituents. 

Simple alkyl and aryl derivatives of nickel(II) with monodentate phosphines are, in general, too unstable to be isolated in the solid state as pure compounds. However, it has been found that a considerable stabilization occurs when the carbon cr-bonded to nickel(II) is part of either an alkynic group, a fluorinated or chlorinated group, or an orf/io-substituted phenyl group. 

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