Kinetics and Mechanism of Decomposition of the β-Chlorovinyl and β-Iodovinyl Complexes of Platinum(IV) in Aqueous Iodide Solutions

It was found that the -iodovinyl and -chlorovinyl complexes of platinum(IV) undergo decomposition in acidic aqueous solutions in the presence of NaI (2.5 M) with the simultaneous formation of acetylene and a corresponding vinyl halide RX (X = Cl, I). The kinetics and the composition of products are consistent with a mechanism that includes an equilibrium step of the reduction of the -halovinyl complexes of Pt(IV) by iodide ions to form corresponding Pt(II) derivatives; the degradation of the above organoplatinum compounds by halogen -elimination to form acetylene; and a step of the protodemetallation of the -vinyl derivatives of Pt(II), which leads to RX. The rate constants of individual steps and the equilibrium constant were estimated.     

Catalytic Chloroplatination of a Triple C-C Bond as an Easy Way to σ-Vinyl Derivative of Platinum(IV) Chloride Complexes

Russian Journal of Organic Chemistry -     

Role of dimethylformamide in generating the active form of platinum for catalyzing the synthesis of diaryls from aryl iodides

A mechanism is proposed for the reaction of aryl iodides with platinum(II) tetrachloride complexes in dimethylformamide including formation of PtCl₃(CONMe₂)²⁻ in the first step through activation of a dimethylformamide C−H bond by platinum(II) and subsequent oxidative addition of ArI to this species. L. M. Litvinenko Institute of Physical Organic and Coal Chemistry, National Academy of Sciences of Ukraine, 70 Lyuksemburg ul., Donetsk 340114, Ukraine. Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 34, No. 4, pp. 244–246, July–August, 1998.     

Synthesis of urea-formaldehyde oligomers without a solvent

A urea-formaldehyde oligomer comparing well with commercially avaliable KF-MT and KF-M resins in the adhesive power was prepared from solid paraform and urea without a solvent.Translated from Zhurnal Prikladnoi Khimii, Vol. 77, No. 9, 2004, pp. 1555–1557.Original Russian Text Copyright © 2004 by Bezbozhnaya, Zamashchikov, Lutsyk.     

Synthesis and spectroscopic characteristics of σ-vinyl derivatives of platinum(<Emphasis Type="SmallCaps">IV</Emphasis>) chloride complexes

A procedure was developed for the synthesis of previously unknown β-chlorovinyl derivatives of Pt^IV chloride complexes by chloroplatination of terminal alkynes catalyzed by Pt^II chloride complexes. The reaction is highly stereoselective and gives only the products of trans-anti-addition of platinum and chlorine atoms. The regioselectivity of the catalytic reaction formally corresponds to Markovnikov’s rule, e.g., in alkynes containing electron-donating substituents, platinum attacks the terminal carbon atom. The σ-vinyl derivatives of Pt^IV chloride complexes were characterized by IR spectroscopy and ¹H and ¹³C NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2380–2384, October, 2005.     

Formation of Ethers from Alcohols with Chloride Complexes of Platinum(II) as Catalysts

A new catalytic reaction of the etherification of alcohols in the system ROH-PtCl ₄ ²⁻ has been observed. At 70 °C in the presence of catalytic amounts of chloride complexes of platinum(II) methanol gave dimethyl ether. Methyl tert-butyl ether and di-tert-butyl ether were formed analogously from a mixture of methanol and tert-butanol. In the reaction with ethanol the products were diethyl ether and a π-ethylene complex of platinum(II). It is suggested that the step-wise mechanism includes the oxidative addition of the alcohol with the intermediate formation of an alkyl complex of platinum(IV), the decomposition of which by reductive elimination under the influence of a second molecule of alcohol or an alkoxide anion gives an ether and regenerates the catalyst, a chloride complex of platinum(II).__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 3, pp. 190–193, May–June, 2005.     

The effect of the coordination sphere of the platinum catalyst on the course of the direct С–С coupling in the systems Pt<Superscript>II</Superscript>–ArH–ArI–base. The experimental and theoretical (DFT) study

The composition of coupling products in reaction of arenes with aryl iodides catalyzed with Pt(phen)Cl₂, Pt(bipy)Cl₂, Pt(py)₂Cl₂ and K₂PtCl₄ complexes was studied. Based on quantum-chemical calculations of the charges on platinum atoms, the energies of the frontier molecular orbitals of the metal complexes and substrates an approach is proposed to forecasting the effect of the structure of the catalyst on the direction of the reaction towards the homo or cross-coupling.     

Selective Oxidation of 5-(Hydroxymethyl)furfural to Furan-2,5-dicarbaldehyde with Sodium Nitrite in Phosphoric Acid

5-(Hydroxymethyl)furfural is readily oxidized to furan-2,5-dicarbaldehyde with sodium nitrite in phosphoric acid at room temperature (25°C). The best selectivity for furan-2,5-dicarbaldehyde is achieved using 2.5 equiv of sodium nitrite with respect to the substrate. In this case, nearly quantitative yield of furan- 2,5-dicarbaldehyde is attained in 1 h, the substrate conversion being complete. Due to high selectivity in combination with low cost and toxicity of phosphoric acid, the system NaNO₂–H₃PO₄ is more convenient than NaNO₂–CF₃COOH for the preparative synthesis of furan-2,5-dicarbaldehyde.     

On the double function of metal ion electrophiles in the hydrolysis of primary alkyl halides

Metal ions are shown to enhance heterolysis of RX as Lewis acids, and as charged particles they affect hydrolysis selectivity.

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