Reactions of Halogen Azides

Until recently, the explosive nature of halogen azides made these compounds unsuitable for preparative uses and greatly impeded investigation of their physical properties. Reactions of ClN₃ and BrN₃ with metal halides, metal carbonyls, and organometallic compounds to from metal azide halides, nitride halides, carbonyl azide halides, and alkylmetal azides were reported only very recently. The stability relationships of the halogen azides are discussed.     

Molecular emission cavity analysis: stimulation of metal halide emissions

Some metal halides (Mn, Co, Ni, Pb and possibly Fe) emit metal(I) halide spectra from the MECA cavity in hydrogen-nitrogen-air flames, in contrast to their behaviour in conventional aspiration flame systems. However, the emission intensity is too weak to provide sensitive analytical applications. Indium halides give intense emissions by either the MECA or aspiration method. Halogenated organic compounds give intense CH and C₂ emissions. Cadmium halides give only an intense atomic emission. Sensitive methods for halides, indium, cadmium and organic compounds are thus possible. Mercury (II) halides and metal fluorides give no measurable emission in the cavity method.     

Crucial Role of Water in the Mechanosynthesis of CsPbI3 and Other ABX3 Halides

Mechanochemical synthesis of CsPbI₃, as a model system for ABX₃ halides, was studied. Water was shown to strongly promote the kinetics of formation of CsPbI₃ from the CsI+PbI₂ mixture through increased mobility of the constituting ionic species. Since many binary and ternary halides are hygroscopic, it was concluded that the presence of small, uncontrollable and unintentional additions of water should often occur in both precursor mixtures and synthesized complex halides boosting the kinetics of formation of many, if not all, ternary organic–inorganic hybrid halides such as, for example, MAPbX₃ (X=Cl, Br, I). In addition, trace amounts of water should influence the transport characteristics of complex halides. Thus, the presence of water explains, at least partially, the huge scatter in both the reported mechanochemical reaction times necessary for obtaining single-phase APbX₃ perovskite halides and the activation energies of ionic diffusion in APbX₃.     

STUDY ON THE CATIONIC POLYMERIZATION OF 1, 3-PENTADIENE INITIATED BY AlCl_3/ALKYL HALIDE SYSTEMS

The cationic polymerizations of 1, 3-pentadiene were initiated by AlCl_3 in n-hexaneat 30℃ in the presence of alkyl halides, i.e., tert-butyl chloride, tert-butyl bromide andisobutyl chloride. The effects of these halides on the polymer yield, molecular weight,crosslinking reaction, cyclization and polymer microstructure, have been investigated. Twomain side reactions, crosslinking and cyclization, were suppressed and reduced by theaddition of the halides. The proportion of 1, 4 units of polymer chains was increasedby the presence of the halides, which reduced the polymer yield and the molecular weightof polymers.     

Covalent nature of the metal-halogen bonds in trinuclear osmium carbonyl halides

Comparison of the results of the electrochemical reduction of trinuclear osmium carbonyl halides with linear structure, Os₃(CO)₁₂X₂, and nonlinear structure, Os₃(CO)₁₀(-X)₂ (X=I, Br, and Cl) with mononuclear carbonyl halides of transition metals indicates covalent nature of the metal-halogen bonds in these compounds. Chemical dissociation does not occur upon dissolving the trinuclear osmium carbonyl halides in acetonitrile and the cleavage of the Os-X bonds is a result of the electrochemical reduction. The observed order for ease of reduction of the trinuclear osmium carbonyl halides coincides with the change in the E_1/2 values in the reduction of the mononuclear carbonyl halides of transition metals and alkyl halides.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 459–460, February, 1990.     

Oxidative addition of heteroaromatic halides to Negishi reagent and subsequent cross-coupling reactions

Heteroarylzirconocene halides were prepared via the oxidative addition of heteroaryl halides to the Negishi reagent ‘Cp₂ZrBu₂’. The palladium-catalyzed cross-coupling of the in situ generated organozirconium reagents with functionalized aryl and heteroaryl halides proceeded smoothly in the presence of CuCl to produce the cross-coupling products in high yields.     

Heteroaryl manganese reagents: direct preparation and reactivity studies

Direct preparation of various heteroaryl manganese reagents was performed by using highly active manganese (Mn∗) and heteroaryl halides. The resulting organomanganese reagents were coupled with electrophiles such as aryl halides, vinyl halides, and benzoyl chlorides under mild reaction conditions. The corresponding coupling products were obtained in good yields.     

Investigation of phase diagrams by DTA and X-ray methods: The systems AX/CoX2 (A = Na-Cs,TI;X = Cl,Br, I)

A combination of differential thermal analysis and X-ray structure analysis is advantageously used to investigate the formation of double halides in complicated systems betweeen alkali halides, AX, and divalent halides, MX₂. Among the systems of CoX₂ (X = Cl, Br.I) this is particularly valid for the systems TICI/CoCl₂ and TlBr/CoBr₂.     

Pyridinium Halides and Their Mixtures as Inhibitors of Steel Corrosion in Sulfuric Acid Solutions

Mixtures of 1-acylmethylpyridinium halides with equimolar amounts of pyridinium halides were prepared by the Ortoleva-King reaction. The inhibiting effect of various pyridinium halides and their mixtures on corrosion of steel in sulfuric acid solutions was studied.__________Translated from Zhurnal Prikladnoi Khimii, Vol. 78, No. 3, 2005, pp. 517–519.Original Russian Text Copyright © 2005 by Yurchenko, Ivashchenko, Pilipenko, Pogrebova.     

Cobalt-catalyzed low pressure double carbonylation of aryl and secondary benzyl halides

α-Ketoacids can be easily synthesized with satisfactory yields and selectivities by carbonylation of aryl halides and secondary benzyl halides under very mild conditions. The reactions are catalyzed by Co₂(CO)₈ in alcoholic solvents; the presence of a methyl source (dimethyl sulfate or methyl iodide) is necessary for the carbonylation of the aryl halides. Base, temperature and solvent have large effects on the course of the reaction.     

Relative energy of organic compounds II. Halides, nitrogen, and sulfur compounds

The energies of the following types of compounds are characterized by their calculated relative enthalpies: alkyl, alkenyl, and aryl halides; carboxylic acid halides; carbonyl halides; amines; carboxylic acid amides; hydrazine derivatives; nitriles; heteroaromatic compounds; nitro-compounds; organic nitrites and nitrates; organic sulfides; thiols; disulfides; sulfoxides; sulfones; organic sulfites and sulfates; and selected inorganic compounds. Stabilization energy of pyrrol and thiophene has been estimated.     

Samarium diiodide as coupling agent between aldehydes and organic halides for the synthesis of homoallylic and homobenzylic alcohols

Many aliphatic aldehydes are transformed into secondary alcohols by reaction with allyl halides or benzylic halides in presence of SmI₂.     

Contributions to the Mechanism of Isobutene Polymerization. VI. Effect of Halides

The effects of various allyl chlorides and alkyl halides on the overall yield of polymerization and molecular weight of polyisobutene have been investigated and expressed quantitatively by poison and transfer coefficients. The poison and transfer coefficients of halides have been compared with those obtained previously for corresponding hydorcarbons. The poison coefficients of halides and hydrocarbons can be treated formally in a similar manner (1/W_p vs. [X] plots linear for both classes); however, the appropriate transfer coefficients indicate fundamentally dissimilar transfer mechanisms in these systems (1/MW_p vs. [X] plots linear for hydrocarbons, whereas 1/MW_p vs. [X]^1/2 plots linear for halides). These results are discussed in terms of the allylic termination mechanism.     

Photochemistry of aryl halides: Photodissociation dynamics

In recent years, the photodissociation dynamics of aryl halides has been a subject of intensive studies, which is closely related to the atmospheric chemistry. Here we present a review on the photochemistry of aryl halides, with emphasis on the recent progress in photodissociation dynamics at 266 nm by using photofragment translational spectroscopy. The ab initio calculations have also been employed to investigate those photodissociation processes. It has been found that the photodissociation of aryl halides at 266 nm is attributed to the nonadiabatic process via intersystem crossings from bound singlet excited state to triplet excited state and/or via internal conversion from bound singlet excited state to ground state. Also, the substitution effects in the photodissociation dynamics of aryl halides are discussed.     

Synthesis of 1,3-Dialkylimidazolium and 1,3-Dialkylbenzimidazolium Salts

A number of N-alkylimidazoles and N-alkylbenzimidazoles were synthesized by reactions of imidazole and benzimidazole with alkyl halides. The reaction rate increases by a factor of 2 to 3 under conditions of microwave activation. Subsequent treatment of the resulting N-alkylazoles with alkyl halides afforded the corresponding 1,3-dialkylimidazolium and 1,3-dialkylbenzimidazolium halides.     

Solvent extraction studies of phosphonium salts and their analytical applications : Differentiation of n- and isopropyl halides

A test is described for identification and differentiation of n-propyl and isopropyl halides. The halide is reacted with triphenylphosphine to form the phosphoniun salt, and thiocyanate and copper or cobalt solutions are added, Extraction of the colored precipitate into a suitable solvent indicates n-propyl halide whereas isopropyl halides yield unextractable products. The test is applicable to solutions of each halide in the corresponding alcohol as well as to mixtures of both halides.     

Stereo-recognizing transformation of (E)-alkenyl halides into sulfides catalyzed by nickel(0) triethyl phosphite complex

(E)-Alkenyl halides were transformed into (E)-alkenyl sulfides by the nickel(0) triethyl phosphite complex-catalyzed reaction with thiols, whereas (Z)-alkenyl halides gave alkynes under the same reaction conditions. Aryl halides were also transformed into aryl sulfides using the same reagent system.     

环烯丙基溴在Cu/SnCl2参与的水相羰基烯丙基化反应中的应用

Five- and six-membered cyclic allylic halides were found to be much less reactive than the acyclic allylic halides in aqueous allylation reactions. Nevertheless, it was found that SnC12/Cu was powerful enough to mediate the aqueous allylation reactions involving cyclic allylic halides. Both the aliphatic and aromatic aldehydes could be efficiently allylated and the reaction condition was mild, simple and safe. The yields were usually in 75%-97% and the reaction was erythro selective.     

Carbonylation of Tertiary Alkyl Halides Synthesis of Pivaloyl Halides

The carbonylation of tert-butyl halides in a two-phase system, RSO₃H/CCl₄, under carbon monoxide pressure affords the corresponding pivaloyl halides in good yields and selectivities.     

Chlor-fluor-austauschreaktionen mit antimonhalogeniden

The kinetics and mechanism of Cl-F exchange between C-Cl-containing compounds and antimony(V) halides are discussed. The reaction proceeds via the formation of fluorine bridges through an S_N mechanism. This contradicts the mechanism proposed by Booth and Swineheart [1]. Complex formation of different antimony halides in the system influences and sometimes inhibits the exchange. The role of other fluorinating agents together with antimony halides is described.