Reformatsky reactions with SmI2 in catalytic amount

A substoichiometric protocol for Reformatsky-type addition of α-haloesters, α-haloketones, α-halonitriles, and α-halophosphonates to carbonyl compounds has been developed. β-Hydroxyesters and β-hydroxynitriles were obtained in good to excellent yields.     

Catalytic, PMe3-mediated conversion of secondary nitroalkanes to ketones: a very mild Nef-type process

Aliphatic secondary nitro compounds are converted to ketones at room temperature, usually in 90-100% yields, by a one-pot reaction with 220-250 mol % of trimethylphosphine (PMe₃) and 50-100 mol % of ^tBuC₆H₄SSC₆H₄^tBu or PhthN-SePh, or 20 mol % of both additives. Thus, very mild catalytic variants of the reductive Nef-like reactions are disclosed.     

Iodine‐Promoted Synthesis of Structurally Ordered AlPd5

The boundary conditions and scope of catalytically stimulated synthesis of ordered intermetallics from solid metals are elucidated. The method is applied to the preparation of AlPd₅. Its crystal structure has been determined by means of x‐ray powder diffractometry. AlPd₅ forms a structurally unmatched ordered variant of the cubic close‐packing of spheres. Above 900 K AlPd₅ is merged in the fcc boundary solid solution Al_xPd_1?x by a first order phase transition. The particular arrangement of the minority component Al and the associated structural distortions are analysed with regard to chemical bonding against the background of the enthalpy‐driven disorder‐order transition.     

Catalysed quaternization of coordinated tertiary amines by ethyl iodide: kinetics and mechanism

A kinetic study of the joint homogeneous–heterogeneous catalysis for the quaternization of silver (I)-coordinated triethylamine and tributilamine by ethyl iodide was performed in toluene. The data obtained substantiated the superficial molecular arrangement, previously proposed by Barbosa and Spiro, and exposed a new competitive reaction of the non-coordinated soluble silver salt with the alkyl halide in the solvent under study. Estimates of the solution rate constants were obtained for both systems and evidence of a surface effect is also presented.     

In(OTf)3 catalysed simple one-pot synthesis of α-amino phosphonates

A new efficient one-pot synthesis of α-amino phosphonates derived from nitro substituted anilines, aldehydes and diethyl phosphite has been carried out by employing 5 mol% of In(OTf)₃. The method is equally effective for the generation of α-amino phosphonates from various carbonyl compounds and other amines.     

Palladium-catalysed amination of 2-acyl-1-alkyl-5-bromopyrroles

The first intermolecular C-N bond-forming reactions between substituted 2-bromopyrroles and primary and cyclic secondary amines were performed using Pd₂(dba)₃ as catalyst with BINAP as the ligand. The aminations proceeded in the presence of NaO^tBu at 80-100 °C in 31-93% yields.     

Kinetic method for determination of nanogram amounts of copper(II) by its catalytic effect on hexacynoferrate(III)-citric acid indicator reaction

This paper describes a highly sensitive, selective catalytic-kinetic-spectrophotometric method for the determination of copper(II) concentration as low as 6 ng ml⁻¹. The method is based on the catalytic effect of copper(II) on the oxidation of citric acid by alkaline hexacyanoferrate(III). The reaction was followed by measuring the decrease in absorbance of hexacyanoferrate(III) at 420 nm (λ_max of [Fe(CN)₆]³⁻, ∈ = 1020 dm³ mol⁻¹ cm⁻¹). The dependence of rate of the indicator reaction on the reaction variables has been studied and discussed to propose a suitable mechanism to get a relation between the reaction rate and [Cu²⁺]. A fixed time procedure has been used to obtain a linear calibration curve between the initial rate and lower [Cu²⁺] or log[Cu²⁺] in the range 1 × 10⁻⁷ to 4 × 10⁻⁴ mol l⁻¹ (6.35-25,400 ng ml⁻¹). The detection limit has been calculated to be 4 ng ml⁻¹. The maximum average error is 3.5%. The effect of the presence of various cations, commonly associated with copper(II) and some anions has also been investigated and discussed. The proposed method is sensitive, accurate, rapid and inexpensive compared to other techniques available for determination of copper(II) in such a large range of concentration. The new method has been successfully applied for the determination of copper(II) in various samples.