A reactivity change of a strontium monohydroxide by umpolung to an acid

Controlled hydrolysis of strontium amide LSrN(SiMe 3) 2(thf) (L = CH(CMe2,6- i-Pr 2C 6H 3N) 2) ( 1) gave an unprecedented example of a hydrocarbon-soluble strontium hydroxide, [LSr(thf)(mu-OH) 2Sr(thf) 2L] ( 2). In compound 2, the tetrahydrofuran (THF) molecules can easily replaced by benzophenone and triphenylphosphine oxide to yield [LSr(mu-OH)(OCPh 2)] 2 ( 3) and [LSr(mu-OH)(OPPh 3)] 2 ( 4) compounds. Among the two strontium atoms of 2, one is coordinated to a single THF molecule, while the other is coordinated to two THF molecules. Interestingly, strontium hydroxide complex 2 behaves as an acid in its reaction with Zr(NMe 2) 4 and results in a heterobimetallic oxide, [LSr(mu-O)Zr(NMe 2) 3] 2 ( 5). Compound 5 is dimeric in the solid state and contains a Sr 2Zr 2O 2 core.     

A new method for the synthesis of aldehyde-spacered oligosaccharides by oxidation of l-tartaric acid derivative

Russian Chemical Bulletin - N-(N-[(2R,3R)-2,3-Dihydroxy-3-carboxypropionyl]glycyl)-β-d-glycopyranosylamines and N-[N-(formylcarbonyl)glycyl]-β-d-glycopyranosylamines, derivatives of...     

Hydrogen-bond quenching of photodecarbonylation in the solid state and recovery of reactivity by co-crystallization

Intermolecular H-bonding between C=O (ketone) and HO (4'-hydroxyphenyl) quenches photodecarbonylation of 2,2,4,4-tetramethyl-1,3-di(4'-hydroxyphenyl)acetone 1 in the crystalline solid state, its reactivity is recovered by co-crystallization with the small organic molecule 4,4'-bicyclohexanone.     

A new method for the preparation of peroxyacetic acid using solid superacid catalysts

A new method for the preparation of peroxyacetic acid from acetic acid and hydrogen peroxide in the presence of solid superacids as a catalyst under mild conditions has been proposed. The preparation of peroxyacetic acid could be carried out in a batchwise operation as well as in a flow-system operation. Nafion-H was found to be active and very stable catalyst for the preparation of peroxyacetic acid and to be regenerated without the loss of catalytic activity.     

Metal-mediated reactivity in the organic solid state: from self-assembled complexes to metal-organic frameworks

The purpose of this tutorial review is to address the use of metal ions to mediate reactions in the organic solid state. We describe metal complexes and coordination networks that facilitate dimerizations, oligomerizations and polymerizations of olefins and acetylenes via irradiation (e.g. ultraviolet (UV) and (60)Co gamma-rays) and thermal annealing. We show how metal ions can be utilized to direct the formation of polymers and molecules. We also describe how supramolecular chemistry has recently influenced dimerization processes in self-assembled metal-organic solids.     

Helix change of polypeptides in the solid state as studied by NMR spectroscopy

The conformational characterization of solid polypeptides has been carried out by means of high-resolution solid-state NMR. It has been demonstrated that high-resolution solid-state NMR spectroscopy is a very useful means for elucidating the structure of polypeptides and proteins in the solid state.     

A modified Ortega method to evaluate the activation energies of solid state reactions

The application of the average linear integral isoconversional method developed by Ortega for evaluating the activation energies of solid state reactions may be hindered by experimental noise and the uncertainties associated with selecting appropriate reaction segments. This paper suggests a procedure, called the modified Ortega method, which can avoid or minimize these hindrances. By applying the modified Ortega method to the kinetic analyses of both simulated and experimental data, a more consistent dependence of the activation energy on the extent of reaction conversion was found with those calculated from the modified Vyazovkin method and the Friedman method.     

Synthesis of azines in solid state: reactivity of solid hydrazine with aldehydes and ketones

Highly conjugated azines were prepared by solid state grinding of solid hydrazine and carbonyl compounds such as aldehydes and ketones, using a mortar and a pestle. Complete conversion to the azine product is generally achieved at room temperature within 24 h, without using solvents or additives. The solid-state reactions afford azines as the sole products with greater than 97% yield, producing only water and carbon dioxide as waste.     

Halogen bonding and pi...pi stacking control reactivity in the solid state

The halogen bonding and the pi...pi stacking interactions induce the noncovalent self-assembly of modules into photoreactive supramolecular architecture. The pi...pi interaction pre-organizes the template, and the halogen bonding aligns the olefins to conform to the topochemical principle for photoreaction. The UV irradiation of the crystal resulted in a cyclization product with quantitative yield and stereospecificity.     

"Lock and key control" of photochromic reactivity by controlling the oxidation/reduction state

A photochemical active triangle terarylene was synthesized and the photochromic behavior was investigated. Its photochromic reactivity can be strongly suppressed by selected oxidization of the sulfur atoms in the molecules. Reactivated photochromic reactivity was obtained by deoxidization of the S, S-dioxide moieties. The suppressed photoactivity of the oxidation state was attributed to the stronger intramolecular hydrogen bonding interactions.     

Exploiting modularity in template-controlled synthesis: a new linear template to direct reactivity within discrete hydrogen-bonded molecular assemblies in the solid state

Co-crystallization of 1,8-naphthalenedicarboxylic acid (1,8-nap) with trans-1,2-bis(n-pyridyl)ethylene (n,n'-bpe) (n = 2 or 4) yields a discrete four-component molecular assembly, 2(n,n'-bpe).2(1,8-nap) 1, that is held together by four O-H...N hydrogen bonds where the dicarboxylic acid, serving as a linear template, directs alignment of olefins in the solid state for [2 + 2] photoreaction.     

Photo and thermal reactivity of halogenocyclohexadienones in charge transfer complexes and in the solid state

This article is a brief survey on studies found in the literature on the development of photoreactive and thermal processes of halogenocyclohexadienones in organized media.     

A method for preliminary estimation of solid oxidation kinetics and mechanism

The possibility of preliminary estimation of the oxidation kinetics and mechanism using the quantity t_o from the exponential kinetic rate equation is discussed.

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, t_o .

     

On the reactivity of innercomplex-bonded palladium : A new specific test for cyanides in alkaline solutions

It has been found that the innercomplex salts of palladium with dimethylglyoxime, (benzildioxime and furildioxime), salicylaldoxime and 8-hydroxyquinolinc do not enter into redox reaction with carbon monoxide, cither in solid or in molecular dispersed form.Solutions of palladium-dimethylglyoxime and palladium-salicylaldoxime in alkali hydroxide or ammonia are masked with respect to many reactions of the palladium as well as of the organic components. In alkaline solutions, when adding alkali cyanide, demasking occurs, with the deliberation of the innercomplex forming organic components. For the processes of dissolution and demasking appropriated equations are suggested.The demasking of dimethylglyoximc in alkaline solutions of palladium dimethylglyoxime permits a new sensitive test for cyanide ion. This cyanide test seems to be appropriate for the detection of illuminating gas.Palladium hydroxyquinorate is insoluble in solutions of alkali cyanides, though it is not precipitable from cyanide containing palladium solutions. An explanation for this “false equilibrium” is suggested.     

Study of oxidation state of plutonium in solution by flow-coulometric method

Reduction rates of Pu(IV) and oxidation rates of Pu(III) have been studied in sulphuric acid and nitric acid media, as functions of acid concentration, plutonium concentration and kind of acid. A flow-coulometric method was used in this work. This procedure has many merits, namely, the sample size required is very small, special reagents are not used, fewer limitations are imposed by the type and concentration of acid, and the method is rapid.     

A new method of estimating monomer reactivity ratios in copolymerization by linear regression methods

Sequential gas-liquid chromotographic analysis of the reaction mixture throughout a copolymerization reaction in conjuction with the improved curve-fitting I (integrated form) method, which accounts for measurements errors in both variables, allows accurate estimation of the monomer reactivity ratios. In this article an alternative method is presented for estimating r values in copolymerization with linear regression only, which is especially suited to cases in which one or two of the r values is close to 1. In these cases the improved curve-fitting I method tends to converge slowly because of the numerical instability of the integrated copolymerization equation. The use of the new method is illustrated for the estimation of the r values for ethylene and vinyl acatate in benzene at 35 kg/cm² and 62°C. The linear regression method was also tried on other copolymerizations and the results are compared with those obtained from the improved curve-fitting I method. The limits of the applicability of the linear regression method were determined by simulated sequential sampling experiments. It appears that the new method is applicable when the product of the r values is between 0.001 and 2, provided both monomer conversions are large enough compared with the measurements error.     

A new method for assessing the efficiency of stabilizers in polyolefins exposed to chlorinated water media

The chlorine used as disinfectant in tap water degrades most materials, including polyethylene. The most adequate (functional) test method, the pressure test, is complicated and expensive because the chlorinated aqueous media (Cl₂ or ClO₂ in water) are unstable and they undergo reactions that are dependent on the pH. A new method which assesses the protection efficiency of phenolic antioxidants in polyolefins was developed. The method uses a liquid hydrocarbon analogue, squalane, in which antioxidants are dissolved. The organic phase was dispersed in the aqueous chlorinated phase (containing 10 ppm of either Cl₂ or ClO₂; pH = 6.8) at 70 °C by intense stirring. The depletion of antioxidant (Irganox 1010) was monitored by standard DSC determination of the oxidation induction time. It was shown that 300 min of exposure was sufficient to obtain useful data.     

A new process for acetic acid production by direct oxidation of ethylene

A new process for acetic acid production by direct oxidation of ethylene which was established and commercialized is described. The catalyst system consisting of Pd and heteropoly acid exhibits excellent activity and selectivity. The addition of Se or Te to the catalyst system is effective to suppress the formation of carbon dioxide. This new process is applicable to a plant of a wide range of size corresponding to the local demand. Because this new process produces little waste water, it is very friendly to the environment.