NaIO4-mediated selective oxidation of alkylarenes and benzylic bromides/alcohols to carbonyl derivatives using water as solvent

A new transition-metal-free, sodium metaperiodate (NaIO4)-mediated direct oxidation of methylarenes and benzylic bromides to the corresponding aromatic carboxylic acids is described. Under the same reaction conditions, benzylic alcohols are selectively oxidized to afford the corresponding aldehydes in good yields without undergoing overoxidation. Unprecedentedly, oxidation of benzyl bromide, toluene, or benzyl alcohol with NaIO4 underwent nuclear bromination followed by oxidation to give 4-bromobenzoic acid in 60-79% yields.     

Cu(ClO(4))(2)-mediated arene C-H bond halogenations of azacalixaromatics using alkali metal halides as halogen sources

Regiospecific halogenation of azacalix[1]arene[3]pyridines at the lower rim position of the benzene ring was achieved from their cross-coupling reaction with cost-effective alkali metal halides through the Cu(ClO(4))(2)-mediated aerobic aryl C-H activation, which gave structurally well-defined aryl-Cu(III) intermediates, and a subsequent C-X bond formation reaction under very mild conditions.     

Crystal lattice energies of alkali metal halides

An empirical relation for crystal binding energy in terms of the valence level splitting of the anion and the radius of the cation has been proposed. The results are much closer to the experimental values and comparable with those obtained by different methods. The anomalously high binding energy of fluorides has been discussed.     

Correlations between photosorption and photocatalytic activities of alkali metal halides

An analysis of the correlation suggests that the common stages in photosorption, photooxidation and photodecomposition of some simple molecules on alkali metal halides are connected with catalyst photoexcitation.

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Interatomic distances in molecules of gaseous alkali metal halides

Summary One of the possible methods of comparative calculation was used for calculating interatomic distancesd in gaseous alkali halides. The average deviation of the calculated values ofd from experimental values was 0.0012 A (for 15 substances).Translated from Zhurnal Strukturnoi Khimii, Vol. 1, No. 4, pp. 399–403, November–December, 1960     

Titanocene-catalyzed carbosilylation of alkenes and dienes using alkyl halides and chlorosilanes

A new method for regioselective carbosilylation of alkenes and dienes has been developed by the use of a titanocene catalyst. This reaction proceeds efficiently at 0 degrees C in THF in the presence of Grignard reagents by the combined use of alkyl halides (R'-X, X = Br or Cl) and chlorotrialkylsilanes (R3'Si-Cl) as the alkylating and silylating reagents, respectively. Terminal alkenes having aryl or silyl substituents (YRC=CH2, Y = Ar or Me3Si, R = H or Me) afford addition products YRC-(SiR'3)-CH2R' in good yields, whereas 1-octene and internal alkenes were sluggish. When 2,3-disubstituted 1,3-butadienes were used instead of alkenes, alkyl and silyl units are introduced at the 1- and 4-positions giving rise to allylsilanes in high yields under similar conditions. The present reaction involves (i) addition of alkyl radicals toward alkenes or dienes, and (ii) electrophilic trapping of benzyl- or allylmagnesium halides with chlorosilanes. The titanocene catalyst plays important roles in generation of these active species, i.e., alkyl radicals and benzyl- or allylmagnesium halides.     

Induced halogenation of alkyl cyclohexenyl ketones involving metal halides,hydrohalogenic acids,and hydrogen peroxide

The induced halogenation and hydroxyhalogenation of alkyl cyclohexenyl ketones in a system [MHlg + HHlg or HHlg]-H₂O₂ or in NaOCl was performed and optimum reaction conditions were established. Under mild conditions the electrophilic addition of the halogen or the acid occurred at the multiple bond of the ring with the formation of the corresponding dihalo or hydroxyhalo derivatives of cycloaliphatic ketones. From the compounds obtained epoxy- and dioxyketones of aliphatic series were prepared. Chloro(bromo)hydrins of ketones from the alkylcyclohexane series and oxiranes based thereon are reactive compounds and can be employed as synthons in the organic synthesis.     

Direct and selective benzylic oxidation of alkylarenes via C-H abstraction using alkali metal bromides

A direct benzylic oxidation of alkylarenes via C-H bond abstraction was developed using alkali metal bromides and oxidants under mild conditions. This reaction proceeded with excellent selectivity by thermal oxidation or photooxidation to provide a broad range of carbonyl compounds containing electron-deficient aryl carbonyl compounds in high yields.     

Nature of the complexes formed by alkali metal halides with phosphine oxides

Reaction of alkali metal halides (MX) with methylenediphosphine oxides and various related compounds in nonaqueous solutions leads to the formation of complex compounds. The compositions, properties, and stabilities of these compounds, which have been studied in detail in acetonitrile, are determined by the nature of the cations and anions of the alkali metal halides. Formation of neutral complexes with the composition [MX · L] and cationic complexes with the composition [ML]⁺ has been established. The most characteristic representative of complexes of the first type is [NaI · L]; in the complexes studied, L=R₂P(O)CH₂P(O)R₂ (R=Bu, BuO, or Ph), Ph₂P(O)CH₂P(O) (OC₂H₅)CH₂P(O)Ph₂ and (p-OCH₃C₆H₄)₂P(O)CH₂P(O)(C₆H₄CF₃-p)₂. Compound [LiL]⁺ is characteristic of complexes of the second type; the compounds containing Ph₃P(O), Ph₂P(O)CH₂P(O)Ph₂, and Ph₂P(O)CH₂P(O)(OC₂H₅)CH₂P(O)Ph₂ as ligands have been studied. Stability constants of the complexes [NaI · L] and [LiL]⁺ have been determined by measuring the dependence of the electrical conductivity of solutions of the alkali metal halides in acetonitrile on the concentration of the ligands. The complex-forming power of phosphine oxides increases with increase in the number of P=O groups. Stabilities of the complexes [NaI · L] with ligands with identical structure decrease with increase in the electronegativity of the substituents on the phosphorus atoms.     

The regioselective C5 halogenation of quinolines using sodium halides under transition metal-free conditions

An efficient and mild halogenation of 8-acylaminoquinoline at the C5 position was described. The reaction utilized easily available sodium halides as the halogen sources and proceeded smoothly under transition metal-free conditions. Various 8-aminoquinolines with a number of functional groups were compatible in this reaction to afford the corresponding halogenated products in moderate to good yields. Moreover, the reaction conditions also tolerated the substrates without the 8-aminoquinolyl auxiliary, such as N-phenyl amide and N-naphthyl amide.     

Nickel-catalyzed carbonylative cycloaddition of allyl halides and alkenes

The carbonylative addition between allyl halides and alkenes is described. The [2+2+1] reaction is catalyzed by Ni(I), and takes place with different strained alkenes under very mild conditions. Changes in solvent and use of different amounts of water in the reaction produce changes on the final products obtained.     

Ion solvation of aqueous solutions of alkali, alkaline earth, and transition metal halides

The published data on the density and velocity of ultrasound are used to determine the ion solvation parameters of sodium, magnesium, and cobalt chlorides. It is shown that the solvation of typical coordination compounds, such as cobalt chloride, is determined by the same underlying systems and interactions as that of electrolytes with ions of alkali and alkaline earth metals.     

Quinones—VII: Halogenation and oxidative halogenation of phenols with hydrogen halides/hydrogen peroxide. Synthesis of p-chloranil and p-bromanil

Chloranil 6 and bromanil 7 are prepared in very good yields from phenol or hydroquinone with concentrated hydrochloric or hydrobromic acid/30% hydrogen peroxide and magnesium chloride as catalyst. With catechol the reaction stops at the tetrachloro- or tetrabromo-o-hydroquinone (4 or 5) stage. The iodination of phenol with potassium iodide/hydrogen-peroxide in acetic acid yields 2,4,6-tri-iodophenol (3).     

An efficient H2O2-based oxidative bromination of alkenes, alkynes, and aromatics by a divanadium-substituted phosphotungstate

A divanadium-substituted phosphotungstate TBA(4)[γ-HPV(2)W(10)O(40)] (TBA = tetra-n-butylammonium) could act as an effective homogeneous catalyst for the H(2)O(2)-based oxidative bromination.