2,2 -Bipyridines dialkyl

Novel catalytic systems, initially used for atom transfer radical additions in organic chemistry, have been employed in polymer science and referred to as atom transfer radical polymerization, ATRP [62-65]. Among the different systems developed, two have been widely used. The first involves the use of ruthenium catalysts [e.g. RuCl2(PPh3)2] in the presence of CC14 as the initiator and aluminum alkoxides as the activators. The second employs the catalytic system CuX/bpy (X = halogen) in the presence of alkyl halides as the initiators. Bpy is a 4,4/-dialkyl-substituted bipyridine, which acts as the catalyst s ligand. 

The formation of N,iV -dialkyl-4,4 -bipyridine cation-radical proceeds through the reduction of the corresponding dication (alkylviologen) by tributylphosphine. Yasui et al. (2001) measured the reaction kinetics in the acetonitrile-methanol mixture. The rate of cation-radical formation decreases in all of the cases when the alkyl groups are deuterated. 

A few syntheses of specific substituted 3,3 -bipyridines have been reported. 6,6 -Dialkyl-3,3 -bipyridines have been shown to be one of the products of the reaction of l-lithio-2-alkyl-l,2-dihydropyridines with perhalometh-anes, cyanogen bromide, or bromine. In an interesting double... 

There has been considerable interest in diquaternary salts of 2,2 -bipyr-idine. Simple 1,1-dialkyl-2,2 -bipyridinium salts are obtained by reaction of 2,2 -bipyridine with excess of an alkyl halide or dialkyl sulfate and related processes, - " and dialkyl diquaternary salts of substituted 2,2 -bipyridines are obtained likewise. " Bridged diquaternary salts are formed by reaction of 2,2 -bipyridines with 1,2-dibromoethane. Thus the parent compound alfords 6,7-dihydrodipyrido-[l,2-a 2, T-c]pyrazinediium... 

There has been much interest in diquaternary salts of 4,4 -bipyridine, the electrochemistry of which has recently been reviewed. l.l -Dialkyl diquaternary salts of 4,4 -bipyridines are prepared by treating 4,4 -bipyri-dines with excess of an alkyl halide or a dialkyl sulfate or other alkylating agent. This method has been used extensively and provides diquaternary salts of type 92 where both alkyl quaternizing groups are the same (i.e., 92 R = 211,467,689,962,967,968 Qf particular interest is the diquater-... 

A number of other routes are available for the syntheses of diquaternary salts of 4,4 -bipyridines. One method that has been extensively studied involves reaction of a 1-alkylpyridinium salt with sodium amalgam (or sodium in liquid ammonia) to form the 1,1 -dialkyl-1,1, 4,4 -tetrahydro-bipyridine, which is readily oxidized to the corresponding l,l -dialkyl diquaternary salt. This reaction is analogous to the synthesis of 4,4 -bipyridine by the action of sodium on pyridine, followed by oxidation of the intermediate tetrahydrobipyridine. " The reduction may be achieved electrolytically or by reaction with zinc or magnesium. Various oxidizing agents have been used to assist the conversion to the di-quaternary Another synthesis of diquaternary salts of... 

Several reactions of diquaternary salts of 4,4 -bipyridine have attracted attention. The behavior of 1,1 -dialkyl diquaternary salts in strong alkaline solution has long been of interest. They give intense blue-violet colorations on treatment with aqueous potassium hydroxide, and the deep color is discharged on shaking in air. The blue-violet color is largely due to radical cations such as 94. The mechanism of the reaction of paraquat dication (95) with alkali has been elucidated. There are several competing... 

The spectra of the radical cations derived from l,r-dialkyl diquaternary salts of 4,4 -bipyridine have received attention, the UV -997,1029,1036.1056 ig spectfa having been well studied. -1057-1059 jg eyjfjejjt from some of these studies that the radical cations are in equilibrium with dimeric species. The Raman spectra of paraquat and its radical cation adsorbed at a silver electrode have also been investigated, whereas a resonance Raman effect with radical cations of viologens has been noted. Other Raman studies at metal... 

The oxidation of l,r-dialkyl diquaternary salts of 4,4 -bipyridine has also been studied. With potassium ferricyanide they give bipyridinones of types 96 and 97. i3.96o gjjjjiiar results were obtained on air oxidation of paraquat at Pyrolysis of paraquat results in demethylation to 4,4 -... 

Quaternary salts of 4,4 -bipyridine other than 1-alkyl or 1-aryl quaternary salts have also been synthesized. Thus l,l -dialkoxy diquaternary salts are formed by reaction of 4,4 -bipyridine l,l -dioxide (see next section) with dialkyl sulfates," and 1-alkyl-I -alkoxy diquaternary salts are obtained similarly. l,r-Bis(2,4-dinitrophenoxy)-4,4 -bipyridinium bisffluoro-borate) has been prepared from 4,4 -bipyridine l,l -dioxide by reaction with 2,4-dinitrobenzenediazonium fluoroborate in sulfolane. Interestingly,... 

Similarly 3- and 4-alkylpyridines give the corresponding 5,5 -dialkyl-2,2 -bipyridines and 4,4 -dialkyl-2,2 -bipyridines, respectively, in good yield when treated with W7-J nickel.5 Somewhat lower yields of 2,2 -biquinolines are obtained with quinolines.6,7... 

Foreman, M.R.S., Hudson, M.J., Drew, G.B.D., Hill, C., Madic, C. 2006. Complexes formed between the quadridentate, heterocyclic molecules 6,6 -bis-(5,6-dialkyl-l,2,4-triazin-3-yl)-2,2 -bipyridine (BTBP) and lanthanides(IH) Implications for the partitioning of actinides(III) and lanthanides(III). Dalton Trans. 13 1645-1653. 

Encouraged by the ID polymer tetrameric cage transformation, other possibilities of transforming metal dialkyl phosphates have been investigated. Interesting among the results obtained so far is the transformation of the ID cobalt-dtbp polymer into a 2D polymeric grid structure by reaction with 2 equiv of 4,4-bipyridine in... 

In the absence of a 4-substituent, 1-alkyl-l-hydropyridinyl radicals dimerize rapidly. Simple 1-alkyl-l-hydropyridinyls, generated electrochemi-cally from the corresponding pyridinium salts, form 1,1 -dialkyl-1,1, 4,4 -tetrahydro-4,4 -bipyridines which are oxidized at the prevailing potential to dialkylviologen cation-radicals which form the final product (Scheme 2 X = H, route abed).230... 

Alk2bipy = 4,4 -dialkyl-2,2 -bipyridine alkyl = tert-buty, nonyl... 

The reaction of dilithium dialkyl bipyridines 44 derived from dilithiation of 3,3 -dimethyl-2,2 -bipyridine with (R EClg (R1 = Me or Ph E = Si, Ge, or Sn) afforded the axially symmetric seven-membered metallacycles 45, which were purified by column chromatography and characterized by their MS and NMR spectra and for 45c and 45e the X-ray structure has been determined. Subsequent reaction of 45d-f with W(CO>6 in toluene gave the corresponding bimetallic complexes 46a-c (Scheme 8) <19970M4839>. 

While artificial photosynthetic mimics come in many manifestations, our efforts have focused predominantly on the class of molecules represented by the structure in Fig. 10.1. These molecules consist of a visible-light-absorbing chromophore in the form of a trisbipyridineruthenium(ll) complex (C) finked by flexible polymethylene chains to one or more electron donors (D) and an electron acceptor (A). The electron acceptor is anAl,W-dialkylated-2,2 -bipyridine (a so-called diquat ) and the electron donors are Al-aUcylated phenothiazines. The diquat type acceptor was chosen because... 

As far as a [RuCbpyla] moiety is concerned, the polar head possesses a rather big volume of about 100 A, which requires the hydrophobic tail to be voluminous enough to compensate such a big head group. To reach this goal, we proposed metallosurfactants containing from one to two and either linear or branched alkyl chain substituted bipyridine, of general formula [Ru(bpy)3 (bpyRa ) ]Cl2 with n = l or 2 and where bpyR stands for a 4,4 -dialkyl-2,2 -bipyridine ligand with x alkyl chains (Fig. 6). 

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