Aryls triaryls

Phosphate Esters. A variety of phosphate esters are used as synthetic lubricants, particularly because of their good fire resistance. They have the general formula OP(OR)2, where R may represent a variety of aryl or alkyl hydrocarbon groups containing four or more carbon atoms to give three broad classes triaryl, trialkyl, and aryl alkyl phosphates (37,38). 

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

An approach to 2,3,5-triaryl-4-imino substituted 1,2,5-thiadiazolidin 5-oxides 242 is the cycloaddition reaction between A -(a-cyano-a-aryl)-methylanilines 240 and sulphinylanilines 241 (99SC(29)911). In this way a number of thiazoli-dine S-oxides 242 could be obtained in satisfactory yield (54-70%). 

Chloro-l-aryl-3//-2-benzazepine /V-oxides, with the exception of the 1,4,5-triaryl derivative 1 which yields the epoxide 2,178 undergo no further oxidation with 3-chioroperoxybenzoic acid (see Section 3.2.1.5.1. ). 8 However, oxidations of l-aryi-3ff-2-benzazepines as their meth-anesulfonates, e.g. 3, with peroxytrifluoroacetic acid produce mixtures of the epoxides, e.g. 4, and the Af-oxides, e.g. 5.78... 

The mem-dichlorobenzene complex reacts with protected 0-aryltyrosines to give aryl ethers. Both chlorine atoms can be sequentially substituted to give symmetrical or disymmetrical triaryl diethers (Scheme XVI). The building up of such diaryl ethers from phenolic compounds which have amino groups in their side chains... 

Dioxo-l,3-diaryl-propane dimerisieren reduktiv zu 3,4-Dihydroxy-1,6-dioxo-1,3,4.6-tetra-aryl-hexanen I, 1,3,5,6-Tctraaryl-2,4,7-trioxa-tricyclo[3.2.1.13 6]n0nanen II und 1,2,4-Trihydroxy-l,2,4-triaryl-3-aroyl-cyclopentancn III4 ... 

Conformational populations of cyanomethylphosphine oxides (136) have been estimated from dipole moments and indicate a preference for the tra/15-conformation. The moments of the o-, m- and p-chloro- and tolyl-derivatives of triaryl phosphites (137, Y = ) and triaryl phosphates (137 Y = O) indicate that the oxygen atom in the latter series causes the aryl rings to rotate further away from a position in which their planes all meet along the molecular symmetry axis. Conformational studies have also been carried out on the dioxaphosphorinanes. The moments of the isomeric series (138a) and (138b) were in the ranges 3.7—4.2 and 5.4—5.5 D respectively. ... 

Synthetic fire-resistant fluids have been developed to replace petroleum-based fluids for many applications. Although there are several types of these less hazardous fluids, the only synthetic fluids discussed in this profile are phosphate esters and polyalphaolefins. The phosphate esters are tertiary esters of orthophosphoric acid, 0=P(0H)3, and may be triaryl, trialkyl, and alkyl/aryl. The polyalphaolefins are usually based on 2-decene and contain a mixture of oligomers (dimers, trimers, etc.). 

The first commercial trialkyl phosphate esters (TAP) were tricresyl phosphate (TCP) and trixylenyl phosphate (TXP), referred to as "natural" phosphate esters because the cresols and xylenols used as raw materials are derived from petroleum oil or coal tar (Marino and Placek 1994). These products are not commercially significant at present however, at waste disposal sites, contaminants from older product formulations may be encountered, particularly those containing the neurotoxic tri-o/T/io-cresyl phosphate isomer. "Synthetic" phosphate esters are derived from synthetic feedstocks. Specific synthetic reactions have been developed to produce triaryl, trialkyl, and alkyl Aryl esters. The triaryl phosphates are currently... 

Before the 1960s, products were introduced based on alkyl aryl phosphates that could contain chlorinated aromatic hydrocarbons. Such products have now entirely disappeared from commercial use, and the vast majority of the industrial organophosphate esters are based on triaryl phosphates with no halogenated components (Marino 1992). However, at older waste disposal sites, hydraulic fluid site contaminants could contain chlorinated hydrocarbons. As with the PCBs formerly included as additives in other forms... 

Organophosphate Ester Hydraulic Fluids. Organophosphate esters are made by condensing an alcohol (aryl or alkyl) with phosphorus oxychloride in the presence of a metal catalyst (Muir 1984) to produce trialkyl, tri(alkyl/aryl), or triaryl phosphates. For the aryl phosphates, phenol or mixtures of alkylated phenols (e.g., isobutylated phenol, a mixture of several /-butylphenols) are used as the starting alcohols to produce potentially very complex mixtures of organophosphate esters. Some phosphate esters (e.g., tricresyl and trixylyl phosphates) are made from phenolic mixtures such as cresylic acid, which is a complex mixture of many phenolic compounds. The composition of these phenols varies with the source of the cresylic acid, as does the resultant phosphate ester. The phosphate esters manufactured from alkylated phenylated phenols are expected to have less batch-to-batch variations than the cresylic acid derived phosphate esters. The differences in physical properties between different manufacturers of the same phosphate ester are expected to be larger than batch-to-batch variations within one manufacturer. 

Muller and co-workers reported the three-component one-pot synthesis of various pyrimidines through the in situ generation of unsaturated carbonyl compounds. The palladium catalyzed coupling of aryl halides bearing electron withdrawing substituents 7 with propargyl alcohols 8 produced unsaturated carbonyl compounds 9 after isomerization, which condensed with amidines 10 to form triaryl pyrimidines 11 . 

The triaryl radicals of germanium exhibit lower g values than their trialkyl counterparts. In part, this arises from increased delocalization of the unpaired spin density onto the aryl rings (and the Ar3Ge radicals do show hyperfme coupling to the ring protons). For example, spin densities for the radicals PhmMe3 mGe, calculated by the Hiickel method (Table 2), reveal that there is a linear correlation between the g value of the radical and... 

The isotropic germanium hyperfine coupling appears to be smaller for the triaryl radicals as compared with the trialkyl radicals. Since the hyperfine coupling to the germanium atom should increase markedly with increased s-character of the orbital containing the unpaired electron, this observation would imply that the aryl-substituted radicals are somewhat more planar than their alkyl-substituted analogues. 

Triaryl phosphites, diaryl alkylphosphonites, and aryl dialkylphosphinites... 

PVC-FR (triaryl phosphate) flexible-5 (FOI 34 %) PVC-FR (alkyl aryl phosphate) flexible-6 (FOI 28 %) PVC rigid-1... 

The rate of reaction of phosphorus oxychloride with phenols to produce triaryl phosphates is increased by the addition of quaternary ammonium salts and the reaction temperature can be reduced without loss of overall yield [1,2]. The analogous reaction between phenoxide anions and thiophosphoryl chloride produces aryl phosphoro-dichloridothoates [3]. As with the acylation of enolizable (3-dicarbonyl compounds (3.3.12), phosphorylation leads to the predominant formation of the E-O-phos-phoryiated derivatives [4,5]. 

Thermolysis of benzoenyneallene (113) in cyclohexadiene at 75 °C produced the cycloaromatized adduct (116) in 22% yield. A biradical is believed to form through a cascade sequence involving an initial Myers cyclization. Trapping of the aryl radical centre in (114) with the tetrarylallenic moiety intramolecularly affords (115), having two triaryl radical centres. Hydrogen abstraction from cyclohexa-1,4-diene by (115)... 

The formation of the heterocycle 1 from the xylylene-bis-phosphonium salt 2 and PCI3 proceeds via a detectable intermediate 3 in a cascade of condensation reactions that is terminated by spontaneous heterolysis of the last remaining P-Cl bond in a cyclic bis-ylide-substituted chlorophosphine formed (Scheme 1) [15]. The reaction scheme is applicable to an arsenic analogue of 1 [15] and to bis-phosphonio-benzophospholides with different triaryl-, aryl-alkyl- and aryl-vinyl-phosphonio groups [16, 18, 19], but failed for trialkylphosphonio-substituted cations here, insufficient acidity prohibited obviously quantitative deprotonation of the phosphonium salts, and only mixtures of products with unreacted starting materials were obtained [19]. The cations were isolated as chloride or bromide salts, but conversion of the anions by complexation with Lewis-acids or metathesis was easily feasible [16, 18, 19] and even salts with organometallic anions ([Co(CO)4] , [CpM(CO)3] (M=Mo, W) were accessible [20]. 

As mentioned above, it is difficult to find organic compounds which are suitable as redox catalysts for oxidations. This is the case because organic cation radicals, which are mostly the active forms in indirect electrochemical oxidations, are usually easily attacked by nucleophiles, thus eliminating them from the regenerative cycle. Therefore, the cation radicals must be stabilized towards the reaction with nucleophiles. Nelson et al. demonstrated that the cation radicals of triaryl amines and related compounds are very stable if the para positions of the aryl... 

It has been shown that aromatic rings of B-triaryl-A/-triaryl substituted rings are orientated perpendicular to the plane of the borazine ring (114,115). If the aryl rings are substituted it is possible to obtain mixtures of cis and trans isomers (atropisomerism) in which the aryl substituents are on the same or opposite sides of the plane of the borazine ring, respectively (115). 

Triazines with three different substituents are formed by variations on the above methods. There is no efficient route to trialkyl or triaryl derivatives, although the reaction of acylimidates and amidines has met with some success (see Section 2.20.4.6.2). In general the best routes available are as follows, (a) Substitution reactions of cyanuric chloride, (b) The condensation of Af-cyanoamidine with chloromethyliminium salts, (c) 2-Aryl-1,3,5-triazin-2-ones may be efficiently prepared by ring closure reactions on AT-(a-chloroalky-lidene)carbamoyl chloride and amidines (see Section 2.20.4.4.1). 

PR = trialkyl, triaryl, mixed alkyl and aryl phosphines... 

A variety of silver(I) complexes of phosphines are known. For triaryl and mixed alkyl-aryl tertiary phosphines, stoichiometries of from 1 1 to 1 4 have been reported, whereas with trialkylphosphines most of the isolated complexes were of 1 1 stoichiometry.169... 

---