Die Thermolyse von Ammoniumphosphormolybdat

Ohne Zusammenfassung     

Thermolyse von 1,2,3-thiadiazolen

Thermolysis of 1,2,3-thiadiazoles leads to nitrogen and primary fragments, which are able to react on several routes. The rearrangement to thioketenes is particularly useful for the synthesis of thiocarboxylic acid-O-esters, which are formed in the presence of alcohols.     

Thermolyse von Cyanokomplexen,VI

Some representatives of alkali hexa- and pentacyanoferrates (ammine, aquo and nitroprussiate) were investigated by a Derivatograph. The natures of the thermal decomposition reactions were clarified by determining the weight losses and gaseous decomposition products. The iron(III) compounds underwent an intramolecular redox reaction with the formation of cyanogen in two steps, the first of which was exothermic and the second endothermic, to form iron(II) cyanoferrate(II). With amminepentacyano and aquopentacyano ferrates the decomposition started unusually in the inner co-ordination sphere: the so-called water of crystallization was released only after the foreign ligand had been removed. The temperatures of decomposition and also the heats of reaction were determined (kcal/mole of complex) and were compared.     

Synthese und Thermolyse von α-Azidoacrylestern

Zusammenfassung Durch Kondensation verschiedener aromatischer bzw. heterocyclischer Aldehyde mit Azidoessigester oder -Azidoacetophenon wurden substituierte Vinylazide hergestellt, deren Thermolyse zu kondensierten Pyrrolen führte. Der Mechanismus wird diskutiert.

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Synthesis and thermolysis of -azidoacrylates (ene-azides, IV)

By condensation of various aromatic and heterocyclic aldehydes with ethyl azidoacetate or -azidoacetophenones substituted vinyl azides were prepared, which yield condensed pyrroles on thermolysis. The mechanism is discussed.

     

Synthesen von Heterocyclen, 139. Mitt.: Zur Thermolyse von Methantricarbonsäurederivaten

Zusammenfassung Die Thermolyse von Methantricarbonsäurederivaten bei vermindertem Druck führt in guten Ausbeuten zu in 3-Stellung substit. Carbostyrilen.

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Syntheses of heterocycles, CXXXIX: Thermolysis of derivatives of methanetricarboxylic acid

The thermolysis of methanetricarboxylate derivatives at reduced pressure gives 3-substituted carbostyriles in good yields.

     

Enazide, 3. Mitt.: Thermolyse von α-Azidozimtestern; Synthese von Indolderivaten

Zusammenfassung Die Thermolyse von -Azidozimtestern führt über die 2H-Azirine mit sehr guten Ausbeuten zu 2-Indolcarbonestern. Ein Mechanismus für die Enazid-Thermolyse wird diskutiert.

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Enazides, III: Thermolysis of -azido-cinnamates. Synthesis of indol carboxylates

Thermolysis of -azidocinnamates gives, through 2H-azirines a good yield of indol-2-carboxylates. A mechanism of the enazide thermolysis is discussed.

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2. Mitt.: Mh. Chem.101, 157 (1970).     

Darstellung und Thermolyse von Lanthanjodat und Lanthanperjodat

Zusammenfassung Durch Fällung von verdünnten Lösungen von Lanthannitrat mit Jodsäure entsteht ein röntgenamorphes Salz der Zusammensetzung La(JO₃)₃·3 H₂O, welches im Bereich von 50–200°C in das wasserfreie amorphe Lanthanjodat übergeht. Bei 350°C erfolgt die Umwandlung der amorphen Form in eine kristalline.Aus Natriummetaperjodat und Lanthannitrat in verd. Lösung gewinnt man ein Mesoperjodat der Zusammensetzung LaJO₅·3 H₂O. Dieses gibt sein Kristallwasser stufenweise ab; bei 120°C entsteht das Dihydrat, bei 166°C das Monohydrat, das bis 290°C stabil ist. Oberhalb dieser Temperatur tritt Zersetzung zu einem amorphen Produkt ein, das J^V und J^VII ungefähr im Verhältnis 2:1 enthält. Auf Grund des IR-Spektrums sind sowohl das Salz LaJO₅·3 H₂O als auch die beiden Zwischenprodukte (LaJO₅·2 H₂O und LaJO₅·H₂O) als Mesoperjodate, nicht als saure Salze der Ortho- beziehungsweise Diperjodsäure anzusehen.

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Preparation and thermal decomposition of lanthanum iodate and lanthanum periodate

The X-ray amorphous salt La(IO₃)₃ has been prepared by precipitation of lanthanum nitrate with iodic acid in dilute solution. Between 50 and 200°C this compound is dehydrated and anhydrous amorphous lanthanum iodate is formed. This product recrystallizes at 350°C.The reaction of sodium metaperiodate with lanthanum nitrate in dilute solution gives lanthanum mesoperiodate, LaIO₅·3 H₂O. Dehydration of this compound leads firstly to dihydrate at 120°C and to monohydrate at 166°C which is stable to 290°C. Higher temperature causes decomposition into an amorphous product with the ratio of I^V: I^VII being approximately 2:1. According to their IR-spectra it is necessary to consider LaIO₅·3 H₂O and both intermediates (LaIO₅·2 H₂O, LaIO₅·H₂O) to be mesoperiodates and not acid salts of orthoperiodic or diperiodic acid.

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Mit 2 Abbildungen     

CIDNP-Effekte bei Photolyse und Thermolyse von substituierten Phenyldiazoniumsalzen

The existence of radical pairs during the photolysis and the thermolysis of substituted benzenediazonium tetrafluoroborates and hydroquinone in acetonitrile is shown by means of CIDNP. The reaction is assumed to occur via a one-electron-step to form first a radical pair consisting of phenyldiazene and p-benzosemiquinone. This radical pair is able to lose nitrogen either by photolysis or thermolysis and can lead either to a disproportionation or to various recombinations.     

Thermolyse von Cyanokomplexen. VII. Über die Thermischen Zersetzungsreaktionen der Hexacyanokobalte(III); Ligandenumlagerungen bei der Thermolyse

Thermolysis of cyano complexes. VII. On the thermal decomposition of hexacyanocobaltate(III); ligand exchange during thermolysis The thermal decomposition of hexacyanocobaltates(III) yields, as products of successive intramolecular redox reactions, first dicyan and Co^II(Co^III)-complexes, then Co^II[Co^II]-complexes and simple Co^II(CN)₂, respectively, and finally Co^ICN and elemental Co, respectively. All the compounds of the [Co^III(NH₃)₆]³⁺ cation with the cyanometallate anions of Co, Fe, Cr, Mn, Ni, Mo yield the same DTA curve as [Co(NH₃)₆][Co(CN)₆] does; in the case of Ni and Cr, which are capable of forming ammine complexes, simultaneous mutual ligand exchange occurs.     

Thermolyse von Arylhalogenboranen; Synthese von 1,3-Dibora- und 1,3-Borasilaindanen

The thermolysis of the 2-silylated or borylated arylboranes (3a-g, or 9a,b) has been investigated. The synthesis of the unknown starting boranes succeeds upon treatment of the (o-(dichloroboryl)phenyl)trimethylsilane (3b) with trimethylalane (giving 3e), tetramethylstannane (giving 3f) or diisopropylamine (giving 3g) and upon trimethylation of the 1,2-bis(dichloroboryl)benzene (9a) with tetramethylstannane (giving 9b). In solution 3b,c, and 9a,b “dimerize” readily in a temperature range between 45 and 135°C with the liberation of halotrimethylsilanes or chloroboranes yielding the 9,10-dibora-9,10-dihydroanthracenes. The reaction mechanism is discussed. To force intramolecular reactions exclusively, flash vacuum pyrolyses (FVP) were performed at about 650°C. When pyrolyzing 3b elimination of hydrogen chloride occurs yielding 1,1-dimethyl-3-chloro-1-sila-3-boraindane (11). After pyrolysis of 11 at 750°C intramolecular, mutual migration of a chloro and a methyl group takes place. Possible rearrangement mechanisms are discussed and have been experimentally in investigated. Hydrogen chloride is the best leaving molecule in these pyrolyses. Extrusion of methanol (from (o-(dimethoxyboryl)phenyl)trimethylsilane (3d)) or methane (from 3e) gives the corresponding borasilaindanes only at 750°C and in lower yields. The synthesis of the very sensitive 1,3-dimethyl-1,3-diboraindane also succeeds by FVP (550°C) starting with 9b. The high-field shifts of the ²⁹Si and the ¹¹B NMR signals of the borasilaindanes compared to the chemical shifts of the corresponding parent bora- and silaindane systems are considered as evidence for a through-bond interaction between both hetero atoms.     

Thermolyse von Phosphor(V)-Schwefel(VI)-nitridhalogeniden

Thermolysis of Phosphorus(V) Sulfur(VI) Nitride Halides Thermolysis of compounds of the type R₂PCl = N–SO₂X (R = Cl, CH₃, C₆H₅; X = F, Cl) results in the formation of the compounds R₂P(O)Cl and [NS(O)X]_n. Pyrolysis of the title compounds with longer chains yields, among others, the cyclic compounds III and IX. IX is also one of the decomposition products of a sulfamide derivative (XXI). Finally the thermal behaviour of carbon containing phosphorus(V) sulfur(VI) nitride chlorides has been investigated.     

Butanolide und Butenolide durch intramolekulare En-Reaktion bei der Thermolyse von Propargyl-propiolaten

Butanolides and Butenolides by Intramolecular Ene-Reaction during Thermolysis of Propargyl Propiolates Gas-phase flow thermolysis of 2-butynyl propynoate ( 1 ) and 2-propynyl 2-butynoate ( 2 ) at 550° afforded 3-ethynyl-2-methyl-2-buten-4-olide ( 4 , 85%) and 2-ethynyl-3-methyl-2-buten-4-olide ( 5 , 80%), respectively. Their formation presumably entails an ene reaction between the methylacetylenic and the acetylenic functions of the diyne esters 1 and 2 to give the two methyliden-vinyliden-butanolides 10 and 11 as intermediates, followed by a [1,5]-H shift to 4 and 5 . At 400–450°, the gas phase flow thermolysis of 1 and 2 led to the dimers 16 (77%) and 17 (6%), respectively. These products resulted from the Diels-Alder dimerization of the above mentioned intermediates 10 and 11 . The regioselectivity of this dimerization is determined by a ‘head-to-head’ approach, with the double bond conjugated to the carbonyl group acting as the dienophile in both cases. The low yield of 17 from 2 is probably due to a further Diels-Alder reaction of the dimer 17 with its precursor 11 , yielding a trimer 18 (8% isolated). This process is not possible when starting with 1 , which explains the higher yield of 16 . The gas phase flow thermolysis of 2-butynyl 2-butynoate ( 3 ) at 550° afforded a mixture of four isomeric products, namely the two monocyclic ethynyl-butenolides 6 and 7 and the two bicyclic vinyl-butenolides 8 and 9 . The formations of 6–9 are also rationalizable by initial ene-reactions, in this case two alternative ones, each involving one of the two CH₃ groups of 3 . This leads to two alkylidene-vinylidene-butenolides, namely 12 and 13 . A [1,5]-H shift converts 12 into 6 and 13 into 7 . A competing alternative [1,5]-H shift transforms both 12 and 13 to the triene 14 , which electrocyclizes to the cyclohexadiene 15 . The latter undergoes two alternative [1,5]-H shifts to yield 8 and 9 .     

Thermolyse von Cyanokomplexen. XII [1] Intramolekulare Redoxvorgänge bei der thermischen Zersetzung von Pentacyanonitrosyl-chromaten und -manganaten

Thermolysis of Cyano Complexes. XII. Intramolecular Oxidation-Reduction Processes during the Thermal Decomposition of Pentacyano Nitrosyl Chromates and Manganates Unequivocal correlations were found in the case of the thermolysis of pentacyano nitrosyl metallates between the wave number of the v_NO band and the splitting-off temperature of NO, as well as between the quality of the decomposition products, and the decompositions hets, depending on the nature of the central atom (Cr, Mn, Fe) and of the cation (Na⁺, K⁺, H⁺, NH₄⁺) of complexes. If the frequency of the v_NO band is low, surprisingly high T_NO values were measured and N₂ and KOCN were formed in exothermic reaction during the decomposition (Cr, Mn). To higher v_NO wave number values belong significantly lower T_NO temperatures, and NO is evolving during the thermolysis in endothermic reaction (Fe). In complexes of higher oxidation state an oxidation-reduction reaction – accompanied by dicyan formation – is also taking place.     

Unkatalysierte sigmatrope 1,5-Wanderung von Acylgruppen bei der Thermolyse von 5-Acyl-5-methyl-1,3-cyclohexadienen

Uncatalyzed Sigmatropic 1,5-Shift of Acyl Groups in the Thermolysis of 5-Acyl-5-methyl-1,3-cyclohexadienes Four different 5-acyl-5-methyl-1,3-cyclohexadienes 1a–d (R = COOCH₃, COCH₃, COC₆H₅, CHO) have been shown to yield mixtures of 1,3-disubstituted cyclohexadienes 2–7 and 1,3-disubstituted aromatic product 8 upon thermolysis at 150–300° in solution and at 350–500° in the gas phase in a flow system. Two reaction pathways (A and B in Scheme 2) are considered for the rearrangement of the C-Skeleton. For the ester 1a ¹³C-isotopic substitution shows that products arise to 75–86% through a 1,5-sigmatropic shift of the methoxycarbonyl group ( A in Scheme 2) and to 14–25% through a sequence of reaction steps involving a 1,7-H-shift reaction in an acyclic intermediate ( B in Scheme 2). For the more reactive compounds 1b–d isomerization is assumed to follow the 1,5-sigmatropic pathway exclusively ( A in Scheme 2). A kinetic study yields the following sequence for the migration tendency of acyl groups toward sigmatropic 1,5-shift: COOCH₃ < COCH₃ < COC₆H₅ < CHO.