Thermal decomposition of ethyl azidoformate in oleitns

Conclusions The mechanism for the thermolysis of ethyl azidoformate in olefins may be regulated by altering the reaction temperature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 226–228, January, 1986.     

Synthesis and carbene decomposition of functionally substituted diazoacetate esters. 6. Propargyl diazoacetate

A synthesis of propargyl diazoacetate (I) was carried out and its chemical transformations were studied. The reaction of (I) in the presence of Rh(OAc)₂ at 25C with 1-pentyne gives the propargyl ester of l-propylcyclopropene-3-carboxylic acid in 80% yield, while reaction with 2,3-dimethyl-2-butene at 60C results in the propargyl ester of tetramethylcyclopropanecarboxylic acid in 10% yield. Compound (I) reacts under the same conditions (35–60C) with ether, CH₂Cl₂ and water, with the formation of propargyl esters of ethoxyacetic, 2,3-dichloropropionic, and a mixture of glycols and 2-[(propyn-2-yl)-oxycarbonyl]methoxy acetic acids in yields of up to 35%. A spontaneous oligomerization of (I) was observed as a result of a dipolar [1, 3]-cycloaddition of the CH=N₂ fragment of one molecule of (I) to the terminal triple bond of the second molecule with the formation of oligomers of 3-hydroxymethylpyrazole-5-carboxylic acid.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 1051–1056, May, 1991.     

Polymer reactions. IV. Thermal decomposition of polypropylene hydroperoxides

The thermal decomposition of polypropylene hydroperoxide (PPH) consists of two consecutive reactions. The initial, faster reaction has rates up to 60 times that of the slower process. The former is largely suppressed by the addition of an excess of 2,6-di-tert-butyl-p-cresol. The course of reaction is the same in either solid state or in solution. The results are consistent with an intramolecular radical-induced mechanism for the initial reaction. This faster reaction consumes about 70–95% of the total hydroperoxides. The decomposition of PPH yields a maximum of about 1.8 radicals. Samples prepared from crystalline and amorphous polypropylenes have identical decomposition kinetics.     

Selenium heterocycles. XXIX. Reaction of substituted 2-thioxo-1,3-thiaselenoles with ethyl diazoacetate,ethyl azidoformate and phenyl azide

Reaction of 5-substituted 2-thioxo-1,3-thiaselenoles with ethyl diazoacetate, phenyl azide and ethyl azidoformate afforded 2-substituted ω-carbethoxy-1,4-thiaselenafulvenes (II) , 5-substituted 2-phenylimino-1,3-thiaselenoles (IV) and 5-substituted 2-carbethoxyimino-1,3-thiaselenoles (V) , respectively. The structure of these compounds were confirmed by spectroscopic methods and chemical analysis.     

Unusual formation of tetrahydropyridazine-3,4,5,6-tetracarboxylic and pyrroletetracarboxylic esters upon decomposition of methyl diazoacetate in the presence of pyridine

Thermal, photolytic, and thermocatalytic decomposition of methyl diazoacetate (MDA) in the presence of Rh₂(OAc)₄ or Cu(acac)₂ in refluxing pyridine afforded isomeric trans,cis- and cis,trans-3,4,5,6-tetra(methoxycarbonyl)-1,4,5,6-tetrahydropyridazines (1 : 1) in a total yield of 30—70%. Decomposition of MDA in refluxing o-xylene in the presence of Rh₂(OAc)₄ and pyridine (20 mol.%) gave rise to 2,3,4,5-tetra(methoxycarbonyl)pyrrole in a yield of up to 40%. In these transformations of MDA, neither dimethyl fumarate (or dimethyl maleate) nor the corresponding 2-pyrazolines were generated as intermediates.     

Thermal stability of copolymers of vinyl acetate and methyl acrylate

The thermal degradation of a series of copolymers of vinyl acetate and methyl acrylate and the two homopolymers poly(vinyl acetate) and poly(methyl acrylate) obtained using Ce(IV) as initiator has been investigated using differential thermal analysis (DTA) and thermogravimetry (TGA) in dynamic nitrogen. The kinetic parameters E, n, and A have been obtained following several methods of thermogravimetric analyses. The stability increases as the methyl acrylate content in the copolymer composition increases. The incorporation of 5 mol % of vinyl acetate in the copolymer produces a marked decrease in stability compared to the homopolymer poly(methyl acrylate). There is evidence for an intramolecular lactonization process in vinyl acetate—methyl acrylate copolymers.     

Thermal decomposition of titanyl oxalates IV. Strontium and calcium titanyl oxalates

Thermal decomposition of strontium titanyl oxalate tetrahydrate and calcium titanyl oxalate hexahydrate have been studied employing TG, DTA, gas and chemical analysis. The decompositions proceed through three major steps: dehydration, decomposition of the oxalate to a carbonate and the decomposition of the carbonate to yield the final products, the metatitanates. The intermediates of the oxalate decomposition are found to be Sr₂Ti₂O_4+x(CO₃)₂-x(CO₂)_x and Ca₂Ti₂O₄(CO₃)₂, respectively. The entrapment of carbon dioxide in the former and the presence of non-equivalent carbonate groups in the latter are substantiated by their i.r. spectra. The penultimate solid residues are poorly crystalline Sr₂Ti₂O₅CO₃ and amorphous Ca₂Ti₂O₅CO₃. Decompositions of these carbonates are accompanied by growth in particle size of the products, SrTiO₃ and CaTiO₃, respectively.     

Thermal decomposition of iron(II) sulphate in air. IV

Heats of decomposition and formation of various hydrates of iron(II) sulphate have been presented and discussed. The heat of dehydration of the monohydrate calculated from the DTA curves (50.2 kJ/mole) appears to be lower than the expected value. The value calculated from the heats of formation (79.4 kJ/mole) is therefore taken as the more accurate value.

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Zusammenfassung Die Zersetzungs- und Bildungswärmen verschiedener Hydrate der Eisen(II)sulfate wurden aufgeführt und diskutiert. Die aus den DTA-Kurven berechnete Dehydratisierungswärme (50.2 kJ) des Monohydrats scheint niedriger zu sein als der erwartete Wert. Der aus den Bildungswärmen berechnete Wert (80.1) kJ) wird deshalb als der exaktere Wert angenommen.

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Résumé On présente et discute les valeurs des chaleurs de décomposition et de formation de divers hydrates du sulfate de fer(II). La chaleur de déshydratation du monohydrate, calculée à partir des courbes d'ATD (50.2 kJ) paraît être plus faible que la valeur attendus. C'est pourquoi la valeur calculée à partir des chaleurs de formation (80.1 kJ) est considérée comme plus exacte.

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(II). , , (50.2 ), . , , , 79.4 .

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The authors express their grateful thanks to Dr. B. R. Sant for his keen interest and valuable suggestions, and to Prof. P. K. Jena, Director, for permitting the publication of the results. One of us (M. S. R. S.) is grateful to the RRL for the award of a Senior Research Fellowship.     

Sulfur-containing vinyl monomers. XIII. Cationic copolymerizations of vinyl sulfides with some vinyl monomers

Cationic copolymerizations of vinyl sulfides (VS) with some vinyl monomers with boron tri-fluoride-diethyl etherate catalyst were investigated to evaluate their monomer reactivities. The effects of VS on the copolymer yield and viscosity of the resulting copolymers revealed the inhibition or retardation mechanism which was explained in terms of the formation of a stable vinylsulfonium salt by the reaction between a propagating carbonium ion and VS monomer. From the results of copolymerizations of phenyl vinyl sulfide (PVS) with isobutyl vinyl ether (IBVE), β-chloroethyl vinyl ether (CEVE), α-methylstyrene (α-MeSt), and styrene (St), the relative reactivities of these monomers were found to be in the following order: IBVE > CEVE > PVS > α-MeSt > St. The relatively higher reactivity of PVS than St derivatives was explained on the basis of the conjugative and electron-donating nature of the VS monomer. The effects of alkyl and para-substituted phenyl groups in vinyl sulfides on their reactivities toward the propagating carbonium ion were correlated with polar factors and compared with those of the hydrolysis of α-mercaptomethyl chlorides. The transition state for the propagation reaction in cationic polymerization of VS was proposed to be a π-complex type structure.     

Thermal stability of poly(vinyl bromide) and copolymers of vinyl bromide with methyl vinyl ketone

Thermal stability and degradation behaviour have been studied for PVB and VB-MVK copolymers spanning the whole composition range, using thermogravimetric analysis. The reactivity ratios in the radial copolymerization were determined by using an NMR technique, leading to r_i(VB) = 3.6 ± 0.2 and r₂(MVK) = 0.2 ± 0.1. The introduction of MVK units into the VB chain leads to an interaction with release of methyl bromide. The stability of the copolymers increases with increasing MVK concentration.     

Catalytic reaction of monosubstituted furazanes with methyl diazoacetate

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 12, p. 2876, December, 1989.     

Thermal decomposition products of poly(vinyl alcohol)

The thermal decomposition of poly(vinyl alcohol) is known to occur in two stages. In a study of first-stage decomposition, this polymer was pyrolyzed in vacuum at 240°C for 4 hr and the products were determined by using gas chromatography. The main products were water, aldehydes having the general formula and methyl ketones having the formula , where n = 0, 1, 2, 3, etc. Mechanisms for the formation of these carbonyl compounds are discussed.     

Studies on amine hydrothiocyanates. IV. Thermal decomposition studies using TG

The thermal decomposition of piperidine hydrothiocyanate, piperazine hydrothiocyanate, and the dihydrothiocyanates of ethylenediamine and 1,3-diaminopropane has been studied using TG. Piperidine hydrothiocyanate decomposes in a single step while the dihydrothiocyanates follow more complicated decomposition patterns yielding H₂S and half of the organic moiety first. The second step involves the loss of H₂S and the remainder of the organic moiety. In each case, complex polymeric materials result. Piperazine hydrothiocyanate also decomposes in two steps, the first involving the loss of half of the piperazine and the second involving the loss of piperazine and H₂S. Kinetic parameters have been determined for all these reactions.     

Thermal decomposition of cesium hexanitratouranium(IV)

As cesium hexanitratouranium(IV), Cs₂U(NO₃)₆, has the same Cs:U stoichiometry as that of Cs₂UO₄, thermal decomposition of this nitrato complex in air and nitrogen was studied in detail as a possible alternate method of preparing pure Cs₂UO₄. The volatility of cesium nitrate, which is one of the intermediate products, changed this Cs:U ratio during thermal decomposition. Hence, only Cs₂U₂O₇ was obtained on heating the sample to 775 K or higher. A scheme for the thermal decomposition of Cs₂U(NO₃)₆ is given by combining the observed TG, XRD and IR data.     

Copper-catalyzed synthesis of vinyl sulfides

[reaction: see text] We report a method for the synthesis of vinyl sulfides using the soluble copper(I) catalyst [Cu(phen)(PPh3)2]NO3. The desired vinyl sulfides are obtained in good to excellent yields, with retention of stereochemistry. This protocol tolerates a wide variety of functional groups or substrates, is palladium-free, and does not require the use of expensive or air-sensitive additives.     

Catalytic reaction of methyl diazoacetate with silylated enynes

Factors affecting the regioselectivity of the catalytic reaction of methyl diatoacetate with 1-trimethylsilylalkene-1-ynes have been revealed. Conditions for selective cyclopropanation of the double bond in 1-trimethylsilylbut-3-ene-1-yne and 1-trimethylsilyl-3-methylbut-3-ene-1-yne in the presence of Rh₂(OAc)₄ have been found.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1248–1252, July, 1993.The authors express their gratitude to B. I. Ugrak and D. E. Dmitriev for help in recording and interpreting the NMR spectra, E. G. Baskir and V. A. Korolyov for taking the chromato-IR spectra and A. A. Kutin for recording the chromato-mass spectra.