Bromination of quinoline in the presence of some lewis acids

Data on the bromination of quinoline in acetic anhydride and in the presence of salts of p and d elements are presented. High catalytic activity of the investigated salts, particularly the salts of p elements, was demonstrated. An unexpected orientation of the bromination of quinoline in 94% sulfuric acid in the presence of copper sulfate was discovered.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 548–550, April, 1985.     

Palladium-catalyzed carbonylation of chlorobenzene in the presence of lewis acids

Carbonylation of chlorobenzene to 4-chlorobenzophenone and/or benzoyl chloride may be catalyzed by PdCl₂ in the presence of Lewis acids MCl₃ (M=Al, Ga). Such a C−Cl bond carbonylation with a phosphine-free catalyst was previosly unknown.     

Synthesis of 4-halotetrahydropyrans from allylsilanes and carbonyl compounds in the presence of lewis acids

An unexpected behavior of the reaction of allylsilanes and carbonylcompounds allowed the stereospecific preparation of differently substituted 4-halotetrahydropyrans with an “all cis” configuration.     

Well-defined boron-containing polymeric lewis acids

A general new route to well-defined polymeric Lewis acids via borylation of silylated polymers is reported. Trimethylsilylated polystyrene (PS-Si) of controlled molecular weight and low polydispersity (PDI < 1.15) was obtained via atom transfer radical polymerization (ATRP) of 4-(trimethylsilyl)styrene. The functional polymer PS-Si was quantitatively borylated using BBr3 to give poly(4-dibromoborylstyrene) (PS-B), a novel soluble boron-containing polymeric Lewis acid. PS-B readily reacted with nucleophiles serving as a precursor to a family of new polymers with boron centers of variable Lewis acidity. Reaction of PS-B with Cu(C6F5) gave the highly Lewis acidic polymer poly[4-bis(pentafluorophenyl)borylstyrene], the first polymeric analogue of tris(pentafluorophenyl)borane.     

New route to fluorinated arylcarbonimidoyl chlorides: Interaction of polyfluoroaryl-amines with halomethanes in the presence of lewis acids

Recently we have described the preparation of polyfluoroarylcarbonimidoyl chlorides by high-temperature copyrolysis of polyfluoroaromatic amines with CCl₄ or pentafluorobenzotrichloride. In presented paper we wish to report a new and convenient route to carbonimidoyl chlorides by interaction of polyfluoroaromatic amines with CCl₄ or pentafluorobenzotrichloride in the presence of AlCl₃ at ordinary temperature. This method gives carbonimidoyl chlorides in high yields.

Polyfluorinated carbonimidoyl chlorides of naphthalene can be also obtained. The possibility of synthesis of both nonfluorinated and polychlorinated arylcarbonimidoyl chlorides, as well as utilization of another halomethanes and Lewis acids will be discussed. Polyfluorinated carbonimidoyl chlorides can be transformed to N-trifluoromethylpolyfluoroanilines according to the following scheme:

A number of reactions of polyfluoroarylcarbonimidoyl chlorides and the mechanistic details of the titled reactions will be considered.     

Unexpected Result of Imidazo[4,5-b]pyridine Bromination

Russian Journal of Organic Chemistry -     

Bromination of 2-benzoylthiophene in the presence of excess aluminum chloride

Russian Chemical Bulletin -     

Reactions of polyolefins with strong lewis acids

Treatment of a cyclohexane solution of low density polyethylene and polystyrene with anhydrous aluminum chloride causes chemical reaction between the two polymers which results in the formation of a graft copolymer. The initial copolymer-forming reaction is very rapid, and prolonged contact of the polymers with aluminum chloride causes subsequent degradation in molecular weight. Treatment of separate solutions of polyethylene, isotactic polypropylene, and ethylene–propylene copolymers with aluminum chloride was studied as a function of time. The intrinsic viscosities of the polymers dropped from initial values of 2.4–6.5 to 0.55–0.85 in 5 min, followed by a slower decline over the next 2 hr. In the case of polypropylene, the low molecular weight fragments largely retained the isotactic structure, which demonstrates that stereochemical isomerization is not a major reaction.     

Extraction of zinc and cadmium thiocyanate complexes in the presence of pyridine and some metal ion separations

Extraction of zinc(II) and cadmium(II) from ammonium thiocyanate solutions has been studied in benzene in the presence of pyridine. The effect of such variables as the pH of aqueous phase and concentration of metal, thiocyanate and pyridine on extraction has been investigated and the extracting species identified. Extraction behaviour of silver(I), manganese(II), cobalt(II), mercury(II) and thallium(III) has also been studied under identical conditions and some binary metal ion separations of analytical and radiochemical importance are reported.     

Reactivity of some α-and α,γ - unsaturated silanes towards acetals in the presence of a lewis acid.

α-and α,γ-unsaturated silanes undergo titanium tetrachloride-induced alkylation of acetals.     

Synthesis in the isocamphane series,XVI. The regioselectivity of some lewis acids in the catalyzed Diels-Alder-reaction of cyclopentadiene and mesityloxide

Zusammenfassung The regioselectivity of 9Lewis acids in the catalyzedDiels-Alder-reaction of cyclopentadiene and mesityloxide is described and theendo: exo-ratio of1 a and1 b determined by quantitative HPLC- and¹H-NMR-measurements. The reaction mixture of1 a+1 b normally contains more of theendo epimer1 a, e.g. 31 for1 a1 b, and is therefore in agreement with theendo rule, only TiCl₄ favors theexo epimer1 b.

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Synthesis in the isocamphane series, XVI. The regioselectivity of some lewis acids in the catalyzed Diels-Alder-reaction of cyclopentadiene and mesityloxideShort communication

Teil der Diplomarbeit vonHuber, U., Universität Wien, 1980.     

Free radical copolymerization in the presence of lewis acids. I. Alternating copolymerization of vinyl acetate with acrylic acid in the presence of GeCl4 and BCl3

Alternating copolymers of vinyl acetate (VAC) and acrylic acid (AA) were obtained by free radical polymerization in the presence of GeCl₄ and BCl₃. For the GeCl₄ system, the reaction rate was proportional to [initiator]^1/2. Optimum rate was obtained when the molar ratio of the monomers was 1:1. The chain transfer agent CCl₄ had no effect on the reaction. By means of ultra-violet spectra analysis, it was concluded that both VAC and AA formed complexes with GeCl₄. ESR analysis gave us the information that salt complexed acrylic acid radical had greater cationic characteristics than uncomplexed radical. Thus the nature of alternation may be due to both complexed AA radical and activated monomer complexes.     

Thermometric titration of acids in pyridine

Thermometric titration of HClO(4), HI, HNO(3), HBr, picric acid o-nitrobenzoic acid, 2,4- and 2,5-dinitrophenol, acetic acid and benzoic acid have been attempted in pyridine as solvent, using 1,3-diphenylguanidine as the base. Except in the case of 2,5-dinitrophenol, acetic acid and benzoic acid, the results are, in general, reasonably satisfactory. The approximate molar heats of neutralization have been calculated.     

Spectrophotometric determination of formaldehyde,glycollic and glyoxalic acids in the presence of glyoxal and some carboxylic acids

A spectrophotometric procedure is described for determining glycollic acid, glyoxalic acid and formaldehyde in the presence of high concentrations of oxalic acid and ammonium oxalate, and in the presence of glyoxal, formic acid, tartaric acid, and dihydroxytartaric acid. Three known spectrophotometric methods required modification. The experimental error under the specified conditions does not exceed ±5%.     

Anionic polymerization of styrene in the presence of pyridine

An interesting effect of pyridine on the anionic polymerization of styrene in THF is described. Pyridine forms a complex with living polystyrene and greatly slows the polymerization rate without changing the degree of polymerization. From kinetic and spectroscopic studies, it was clear that there exist two active species in this system and the complex between living polystyrene and pyridine was of the 1:1 type, which itself had a weak ability to grow. The formation constant of the complex K was found to be about 4 × 10⁵ l./mole. The effect of substituted pyridine was also studied and the nature of the complex was discussed.