Darío Doller

The functionalisation of saturated hydrocarbons. Part XXI. The Fe(III)-catalyzed and the Cu(II)-catalyzed oxidation of saturated hydrocarbons by hydrogen peroxide: a comparative study☆

Abstract The selective functionalisation of saturated hydrocarbons catalyzed by copper or iron salts are compared. In addition to further studies on the homogeneous oxidation by Cu(II)-H2O2 is pyridine-acetic acid (GoChAgg system), we introduce a heterogeneous GifIII-analog based on Cu0 and dioxygen in pyridine-acetic acid. Both Cu-based systems display Gif-type reactivity. The intermediacy of alkyl hydroperoxides in the Cu(II)-catalyzed reaction has been proven spectroscopically (following the reaction on [1-13C]-cyclohexane by 13C-N.M.R. spectroscopy) and chemically (quenching the reaction with triphenylphosphine to reduce the hydroperoxide to alcohol). The same holds for Cu0/O2 system, as shown by the effect of triphenylphosphine added to the reaction mixture. Thus, both reactions follow the pathway alkane → alkyl hydroperoxide → alcohol or ketone. Experiments running the GoChAgg reaction (H2O2-based) under an 18O2-atmosphere showed the incorporation of 18O2 into the hydroperoxide and the alcohol (which derives itself from the alkyl hydroperoxide). The relative reactivity of this Cu(II) system was studied for a series of cycloalkanes. The participation of another reaction intermediate (A) has also been demonstrated. However, some important differences are presented, that show that the chemical properties of the Cu-A and the Fe-A intermediates are different. Thus, Gif-type reactivity is metal-dependent and involves two chemically different non-radical species.

The functionalization of saturated hydrocarbons. Part XIX. Oxidation of alkanes by H2O2 in pyridine catalyzed by copper(II) Complexes. A Gif-Type Reaction.☆

Abstract The Cu II -catalyzed oxidation of saturated hydrocarbons by hydrogen peroxide proceeds in pyridine-acetic acid solutions affording mainly ketones as the reaction product. The conversion of hydrocarbon is about 20–30 %. This system (called GoChAgg) shares with the Fe III -catalyzed system (GoAgg II ) its unusual chemical characteristics.

Comparison of gif-type reactivity towards alkanes with standard radical reaction selectivity. Gif oxidation of n-butane and propane

Abstract A precise comparison has been made between radical bromination of a series of saturated hydrocarbons using BrCCl 3 and the bromination of the same series with the same reagent under Gif-type (GoAgg III ) conditions. The relative reactivities in the two series are completely different and confirm a difference in mechanism. Experiments with n -butane and with propane have shown that these gases react with the usual Gif selectivity to furnish 2-butanone and acetone respectively.

The Fe(III)-catalyzed functionalization of saturated hydrocarbons by tert-butyl hydroperoxide: Mechanistic studies on the role of dioxygen

Abstract The Fe(III)-catalyzed ketonization of saturated hydrocarbons by tert-butyl hydroperoxide (TBHP) in pyridine-acetic acid or acetonitrile solution follows the reaction pathway alkane → alkyl hydroperoxide → ketone or alcohol. Dioxygen (O2) is the precursor of the oxygen atoms in the alkyl hydroperoxide, the alcohol, and the ketone.

The functionalization of saturated hydrocarbons. Part 23. Gif-type bromination and chlorination of saturated hydrocarbons: a non-radical reaction☆

Abstract The bromination of saturated hydrocarbons was studied in the GoAgg III system using CBrCl 3 and other polyhaloalkanes. This bromination reaction was compared to free radical processes by (i) evaluating the rates of reactions for a series of polyhaloalkanes, by (ii) measuring the selectivity of the different systems towards various saturated hydrocarbons and by (iii) analyzing the product distribution arising from the bromination of cyclohexyl bromide under both the GoAgg III type conditions and from known processes for alkyl radical generation. Some chlorine containing reagents were also examined for CCl bond formation in the GoAgg III system. All the experimental findings support a mechanism for the reaction that is different from one involving free radicals. This non-radical pathway is common in all Gif-type systems, as seen in common patterns of selectivity. conditions is in agreement with a non-radical reaction pathway for the Gif-type bromination and chlorination reactions.

New alkane functionalization reactions based on gif-type chemistry in the presence of alkali metal salts.

Abstract Cycloalkanes are transformed into monosubstituted cycloalkyl derivatives (chloride, azide, cyanide, thiocyanate, dicycloalkyl disulfide, or nitroalkane

An unprecedented chemical transformation: the oxidation of alkanes to alkyl dimethyl phosphates

Abstract Treatment of alkanes under Gif IV conditions [FedCl 2 .4H 2 O (cat.), Zn 0 , and O 2 in pyridine-acetic acid] in the presence of trimethylphosphite afforded alkyl dimethyl phosphates; 13 C-NMR experiments showed that the phosphates are formed from the reaction between the intermediate alkyl hydroperoxide and trimethyl phosphite in the presence of an iron catalyst.

Studies on the bromination of saturated hydrocarbons Under GoAggIII conditions

Abstract The bromination reaction of saturated hydrocarbons under GoAggIII conditons (FeCl3.6H2O picolinic acid, H2O2 in pyridine/acetic acid) and under radical chain conditions (dibenzoyl peroxide in pyridine/acetic acid or initiation by UV light) are compared. Differences in the selectivity and kinetic behavior for a series of polyhaloalkanes are in agreement with a non-radical mechanism for GoAggIII bromination. Comparison of the kinetic order of reactivity for a series of polyhaloalkanes under chain radical conditions and under GoAggIII conditions is in agreement with a non-radical reaction pathway for the Gif-type bromination reaction.

Metal dependence in gif-type reactions. The Cu(II)-catalyzed olefination of saturated hydrocarbons by tert-butyl hydroperoxide.

Cycloalkanes are transformed into the corresponding cycloalkenes by treatment with tert-butyl hydroperoxide (TBHP) in pyridine/acetic acid solution in the presence of Cu(OAc)2.H2O. When iron salts used instead of copper salts, the major reaction product is the corresponding ketone. Differences between the iron-catalyzed and the copper-catalyzed reactions support a metal-dependent reaction pathway.

Efficient syntheses of 2-(2,6-dichloro-4-trifluoromethyl-phenyl)tetrahydrocyclopenta, tetrahydrothiopyrano, hexahydrocycloheptapyrazoles and tetrahydroindazoles

Two methods are described for the regiospecific synthesis of 3,4-fused-cycloalkyl-1-arylpyrazoles; the key step is the reaction between aryl hydrazines and cyclic α-(dimethoxymethyl)ketones. The latter are obtained by BF3-promoted alkylation of ketones with trimethylorthoformate.