Tetraphenyl ethanes

A series of at least 14 papers [200-208] have been published dealing with the synthesis of telechelic polymers or block copolymers from the radical polymerization of various vinyl monomers with substituted 1,1,2,2-tetraphenyl ethanes. These aromatic compounds, known for over a century [209], are efficient in radical polymerization [201,210], They behave as both initiators and terminating agents [200] that can be involved in living radical polymerization as illustrated in the following reaction ... 

To a dichloromethane solution of triphenylbismuthine N-tosylimide (0.5 mmol), generated in situ from the corresponding bismuthine and iminoiodobenzene, was added 1,1,2,2-tetraphenyl-ethane-l,2-diol (0.5 mmol) at room temperature. Within a few minutes, the reaction completed to afford triphenylbismuthine (99%), benzophenone (99%) and p-toluenesulfonamide (80%) [96JCR(S)24]. 

Figure 17 Photocyclization reactions of piperidine and morpholine derivatives as guest molecules in solid inclusion compounds (a) photocyclization of 1-(phenylglyoxyloyl)piperidine in its inclusion compounds with hosts B and A (Figure 1). (b) Photocyclization of 4-(phenylglyoxyloyl)morpholine in its inclusion compounds with hosts B (Figure 1) and L. (c) The molecular structure of host molecule L (1,1,2,2-tetraphenyl-ethane-l,2-diol).

Whereas 1,1,1-triphenylethane 551 gave only 2% of triphenylacetic acid 552 after treatment with lithium and a substoichiometric amount (50%) of biphenyl, followed by carbonation and acidic hydrolysis, the same process carried out starting from 1,1,1,2-tetraphenyl ethane 553 or 1,1,2,2-tetraphenylethane 554 gave tri- 552 or diphenylacetic acid 555, respectively, with excellent yields (Scheme 148). ... 

This radical is relatively stable (we shall see why shortly), but reacts with itself reversibly in solution. The product of the dimerization of triphenylmethyl was for 70 years believed to be tetraphenyl ethane but, in 1970, NMR showed that it was, in fact, an unsymmetrical dimer. 

Analogous derivatives of ethane and other hydrocarbons are known. Diphenylethane, C6H5CH2.CH2C6HB, and tetraphenyl-ethane, (C6H5)2CH.CH(C6Hb)2, are examples. Similar substitution-products of unsaturated hydrocarbons are of interest. Tetraphenylethylene, (C6H5)2C=C(C6Hb)2, will be described later. 

Thermolysis of these ethanes also generates aH radicals. In all cases, the latter have been detected by esr spectrometry (Ballester et al., 1973). Above 150°C, in inert solvents, an equilibrium in the homolysis of those tetraphenyl-ethanes and their radicals is established. From the relevant esr data, the parameters given in Table 2 have been obtained. When the thermolysis of tetrakis(4-methoxyphenyl)ethane is conducted at 160°C, in noninert solvents such as glyme, a//,a//-diphenylmethane results (Barrios, 1989). 

Arylalkanes and Arylalkenes (Table VIII, p. 181). Diphenylmethane is sulfonated exclusively in the para position rather than in the more hindered ortho position. The 4-sulfonic acid is prepared by treating diphenylmethane with chlorosulfonic acid in chloroform solution at 0 the 4,4 -disulfonic acid, by the action of oleum at 100 . 1,2-Diphenyl-ethane (bibenzyl) when heated with sulfuric acid " jdelds a mixture of a disulfonic acid (probably 4,4 ) and a tetrasulfonic acid. Oleum reacts with stilbene without affecting the olefinic linkage to 3deld a disulfonic acid of unknown structure. Triphenylmethane, sj/m-tetraphenyl-ethane, and tetraphenylethylene yield sulfonic acids containing one sulfo group for each benzene ring, probably in the para position. 

AIBN2O4C64H82, Aluminum, bisftetrahydro furan)-l,2-bis(2-hydroxy-3,5-bis(tcrt-butyl)-benzylideneimino)ethane-, tetraphenyl borate, 34 19... 

Ethane 2-Fluoro-1-methoxy-tetraphenyl- ElOa, 465 (En + N —F-Comp.)... 

Three carbon—carbon initiators are currently available commercially, 2,3-dimethyl-2,3-diphenylbutane [1889-67-4] (1), 3,1 dimethyl 3,1 (llplicnylllrxanc [10192-93-5] (2), and l,l,2,2-tetraphenyl-l,2-bis(trimethylsiloxy)ethane [22341-08-8] (3). 

Ar O = 2,6-di-f-butylphenoxide acac = acetylacetonate bppy = 4-(l-butylpentyl)pyridine cup = cupferron dippe = l,2-bis(diisopropylphosphino)ethane dppe = l,2-bis(diphe-nylphosphino)ethane fee = face-centered cubic = CH(Cp3)2 hep = hexagonal close-packed hexone = methyl isobutyl ketone OEP = octaethylporphyrinogen phen = phenanthroline py = 4-pyrrolidinopyridine tritox = (f-Bu)3CO tbp = BU3PO4 TPP = tetraphenyl-porphyrino-gen trmpe = tris(dimethylphosphinomethyl)ethane. 

Related anchored l,l,3,3-tetraphenyl-2-oxa-l,3-diphospholanium bis-triflate (39) has been prepared by reaction of brominated poly(styrene-co-divinylbenzene) resin 38 with the phosphorous anion generated from l,2-bis(diphenylphosphino)ethane and sodium naphthalenide followed by further oxidation and reaction with triflic anhydride (Scheme 7.13) [55]. This supported reagent has also been employed, to a lesser extent than 37, for the formation of esters and amides by reaction of carboxylic acids with primary alcohols and amines, respectively. 

Scheme 11 Polymerization mechanism for methyl methacrylate with 1,1,2,2-tetraphenyl-l,2-bis(trimethylsiloxy)ethane...

An interesting reaction is that of the salt Na[Al(C2H5)4Cl] with benzene in the presence of sodium alkoxide this gives ethane and sodium tetraphenyl-aluminate Na[Al(C6H5)4], from which triphenylaluminum can be obtained by means of dimethylaluminum chloride. This opens the way to obtain phenyl-aluminum compounds from the ethylaluminum compounds that are readily accessible by direct synthesis.261... 

Carbon-Metallic Linkages. Compounds containing such linkages may be cleaved by hydrogenolysis to give the metal and hydrocarbons. Thus, lead tetraphenyl on treatment with hydrogen at a pressure of 1,000 psig and a temperature of 200°C yields lead and benzene. Tin tetraethyl on Rimilar treatment is converted to tin and ethane. 

Recent studies on the allylation of alkynes with bis (7r-allyl) nickel have revealed that the Ni(0) generated in this process causes the trimeri-zation and, more importantly, the reductive dimerization of a portion of the alkyne (8). A deuterolytic work-up led to the terminally di-deuter-ated diene (5), supporting the presence of a nickelole precursor (4) (Scheme 1). The further interaction of 4 with 1, either in a Diels-Alder fashion (6) or by alkyne insertion in a C-Ni bond (7), could lead to the cyclic trimer 8 after extrusion of Ni(0), thereby accounting for the trimerizing action of Ni(0) on alkynes. This detection of dimer 5 then provided impetus for the synthesis of the unknown nickelole system to learn if its properties would accord with this proposed reaction scheme. Therefore, E,E-l,4-dilithio-l,2,3,4-tetraphenyl-l,3-butadiene (9) was treated with bis (triphenylphosphine) nickel (II) chloride or l,2-bis(di-phenylphosphino ethane)nickel(II) chloride to form the nickelole 10 (9) (Scheme 2). The nickelole reacted with dimethyl acetylenedicarboxylate to yield 11 and with CO to produce 12. Finally, in keeping with the hypothesis offered in Scheme 1, 10a did act as a trimerizing catalyst toward diphenylacetylene (13) to yield 14. 

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