Functionalization of saturated hydrocarbons by means of aprotic superacids 1. Ionic bromination of alkanes and cycloalkanes

Aprotic organic superacids with the composition AcBr·2AlX₃ (X=Cl, Br) are efficient catalysts (Cat) for the bromination of n-alkanes and cycloalkanes by molecular bromine. Under the given conditions, the reactions afford (predominantly or exclusively) monobromides in high yields.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2028–2033, September, 1989.     

Functionalization of saturated hydrocarbons by aprotic superacids 5. Regioselective carbonylation of propane in an organic solvent initiated by aprotic organic superacids CX4·nAlBr 3 (X = Br,Cl;n = 1 or 2)

Aprotic organic superacids CX₄ ·nAlBr₃ (X = Br, CI; n = 1 or 2) are effective initiators of carbonylation of propane with CO in an organic solvent at -10 to -20 °C.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1214–1216, May, 1996.     

Functionalization of saturated hydrocarbons

Alkanes and cycloalkanes (isobutane, butane, isopentane, isohexane, and methylcyclopentane) react with benzene or bromobenzene at 0–20 °C in the presence of RCO⁺Al₂X₇ ^– complexes (R=Me, Pr, or Ph; X=Cl or Br) to give products of the alkylacylation of arenes. The yields of alkylated aromatic ketones reach 60–87 % in 5–30 min, whereas the yields of unalkylated aromatic ketones (the competitive reaction) reach 0–40 %. The reactions of isobutane or isopentane with benzene result exclusively inpara isomers oft-BuC₆H₄COR or a mixture of Me₂(Et)CC₆H₄COR and Me(i-Pr)CHC₆H₄COR isomers (11), respectively. The reaction of isobutane with benzene also proceeds regioselectively and gives only one isomer, 2-Br-t-BuC₆H₄COR.For Part 2 seeIzv. Akad. Nauk, Ser. Khim., 1991, No 1, 105 [Bull. Acad. Sci. USSR. Div. Chem. Sci., 1991, No 1, 90 (Engl. Transl)].Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1253–1257, July, 1993.The authors express their gratitude to B. I. Bakhmutov for his assistance in interpreting the spectra.     

Functionalization of saturated hydrocarbons by aprotic superacids 4. Ionic bromination of ethane and other alkanes and cycloalkanes with molecular bromine in the presence of systems based on polyhalomethanes and AlBr3 under mild conditions

Aprotic organic superacids CBr₄ · 2AlBr3, CBr₄ · AIBr₃, CHBr₃ · 2AlBr₃, CCl₄ · 2AlBr3, and C₆F₅CF₃ -2AlBr3 efficiently catalyze the bromination of alkanes and cycloalkanes with Br₂. Ethane is selectively brominated at 55–65 °C to give mostly 1,2-dibromoethane (stoichiometric reaction). Propane, butane, cyclopentane, cyclohexane, and methylcyclopentane react with Br₂ at -40 to -20 °C with good selectivity affording monobromides in high yields (catalytic reactions).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1208–1213, May, 1996.     

Functionalization of saturated hydrocarbons. High temperature bromination of octahydropentalene. Part 19

The synthesis and thermal bromination of octahydropentalene was studied. The reaction afforded 1a,3a,4b,6b-tetrabromo-1,2,3,4,5,6-hexahydropentalene (14) with remarkable regio- and stereospecificity. The structure of the product was determined by ¹H and ¹³C NMR data and single X-ray structural analysis. The treatment of octahydropentalene with tenfold bromine gave the octabromopentalene derivative. The formation mechanism of the products is discussed.     

Eigenvalues of saturated hydrocarbons

A simplified Hückel-type molecular-orbital (MO) model for the valence electrons of saturated hydrocarbons is proposed and the consequent eigenvalue spectrum considered. A first foundational result is obtained, which every chemist “knows”, namely that: alkanes are stable, with half their (Hückel-type MO) eigenvalues positive and half negative.     

Quenching of anthracene fluorescence by dialkylanilines in saturated hydrocarbons

The bimolecular quenching constants of anthracene fluorescence by dialkylanilines in saturated hydrocarbons depend on the solvent viscosity and may exceed theoretical diffusion controlled limit in viscous hydrocarbons.     

Functionalization of saturated fluorocarbons with and without light

Photochemical transformation of saturated fluorocarbons into tetrabutylammonium enolates has been improved, and a method employing ketyls as reductants has been developed that accomplishes the same chemistry without light. Enolates have been isolated as enol methyl ethers, from which they can be efficiently regenerated with tetrabutylammonium iodide. In other cases, enolates have been isolated as the corresponding ketone or stable enol. Fluorocarbon LUMO energies correlate with their reactivity and serve as a guide to the choice of ketyl. Use of this chemistry for fluoropolymer surface modification is discussed.     

Oxidation rate of saturated hydrocarbons by permanganate in aqueous solutions

Conclusions The reaction for the oxidation of alkanes in aqueous permanganate solutions is first order in both substrate and oxidizing agent. The reaction rate constants were measured for a number of C₃-C₇ normal, iso-, and cycloalkanes. The normal type of selectivity is fulfilled: the tertiary C-H bonds are more active, while the primary C-H bonds are less active than the secondary C-H bonds.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1654–1656, July, 1982.     

Hypochlorite-oxyfunctionalization of saturated hydrocarbons catalysed by ruthenium(II) complexes

Hydroxylation or ketonization of alkanes is achieved using lithium or sodium hypochlorite in the presence of catalytic amounts of ruthenium(II) complexes in a biphasic dichloromethane—water system, at room temperature. The oxidation of cyclooctane is first order both in substrate and in catalyst: a kinetic isotope effect (k_H/k_D) = 5.6 was measured using cyclohexane-d₁₂. A discussion is included concerning the origin of the different regioselectivities.     

Sulfooxidation of saturated hydrocarbons,initiated by ozone and hydrogen peroxide

Conclusions The effect of hydrogen peroxide on the ozone-initiated sulfooxidation rate of saturated hydrocarbons was studied. The addition of 0.5–1% H₂O₂ of the hydrocarbon volume leads to an increase in the reaction rate by 5–10 times and the formation of clear reaction products.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 731–732, March, 1978.